Common Cardiac Issues in Pediatrics 9781610021456

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 9781610021456

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Table of contents :
Contents......Page 12
Introduction......Page 18
PART 1: Evaluation of the Patient......Page 20
1. Clinical History and Physical Examination......Page 22
2. Electrocardiography......Page 32
3. The Role of Echocardiography......Page 68
4. Basics of Exercise Testing......Page 90
5. Chest Radiography......Page 98
6. Cardiac MR Imaging and CT......Page 114
7. Laboratory Studies......Page 128
PART 2: Common Signs and Symptoms......Page 134
8. Chest Pain......Page 136
9. Syncope......Page 152
10. Palpitations and Arrhythmia......Page 166
11. Heart Murmur......Page 180
12. Evaluation of the Neonate With Congenital Heart Disease......Page 190
PART 3: Congenital Heart Disease......Page 204
13. Fetal and Newborn Transitional Circulations......Page 206
14. Neonatal Screening for Heart Disease......Page 216
15. Surgical Procedures for Congenital Heart Disease......Page 224
16. Office Care of the Child After Cardiac Surgery......Page 256
17. Common Syndromes Associated With Cardiac Lesions......Page 264
18. Adults With Congenital Heart Disease......Page 288
Aortic Valve Problems, Including Bicuspid Aortic Valve and Subaortic Membranes......Page 306
Atrial Septal Defects......Page 311
Atrioventricular Canal Defects......Page 315
Coarctation of the Aorta......Page 319
“Congenitally Corrected” Transposition of the Great Arteries......Page 324
Mitral Valve Anomalies......Page 327
Patent Ductus Arteriosus......Page 330
Patent Foramen Ovale......Page 333
Pulmonary Stenosis......Page 335
Single-Ventricle Lesions......Page 339
Systemic and Pulmonary Vein Anomalies......Page 344
Tetralogy of Fallot......Page 348
Transposition of the Great Arteries......Page 353
Tricuspid Valve Anomalies......Page 358
Truncus Arteriosus......Page 362
Vascular Rings and Slings......Page 366
Ventricular Septal Defects......Page 372
PART 4: Cardiomyopathies and Channelopathies......Page 378
20: Hypertrophic Cardiomyopathy......Page 380
21. Dilated Cardiomyopathy......Page 396
22. Restrictive Cardiomyopathy......Page 406
23. Noncompaction Cardiomyopathy......Page 414
24. Long QT Syndrome and Other Channelopathies......Page 430
PART 5: Acquired Cardiac Diseases......Page 440
25. Kawasaki Disease......Page 442
26. Acute Rheumatic Fever and Rheumatic Heart Disease......Page 462
27. Cardiotoxicity Among Survivors of Childhood Cancer......Page 482
PART 6: Infectious Diseases......Page 494
28. Vaccines for Patients With Cardiac Conditions......Page 496
29. Lyme Carditis......Page 506
30. Endocarditis......Page 516
31. Prevention of Bacterial Endocarditis......Page 530
32. Myocarditis......Page 536
33. Pericardial Diseases......Page 548
PART 7: Preventive Cardiology......Page 562
34. Dyslipidemia......Page 564
35. Hypertension......Page 586
36. Cardiac Screening Prior to ADHD Treatment......Page 614
37. Cardiac Screening for Athletic Participation......Page 622
38. Autonomic Dysfunction......Page 632
PART 8: General Issues in Primary Cardiac Care......Page 644
39. Neurodevelopmental and Psychosocial Outcomes in Children With Congenital Heart Disease......Page 646
40. Lifestyle Counseling......Page 662
41. Cardiac Pharmacology......Page 674
42. Transition and Transfer From Pediatric to Adult-Centered Cardiac Care......Page 704
PART 9: Special Conditions......Page 718
43. Cardiac Transplantation......Page 720
44. Pulmonary Hypertension......Page 732
Index......Page 746

Citation preview

Editors Jonathan N. Johnson, MD, FACC, FAAP, and Deepak M. Kamat, MD, PhD, FAAP Learn from leading experts the latest information on ­cardiac issues that present most often in a pediatric office. The scope of focus includes signs and symptoms, management of patients with acquired or congenital heart disease, ­cardiac implications of common infectious diseases, preventive cardiology, and other issues that are frequently managed or evaluated by the primary care pediatrician.

For other pediatric resources, visit the American Academy of Pediatrics at shop.aap.org.

JOHNSON ∞ KAMAT

Topics include • Electrocardiography • Heart Murmur • Syncope • Cardiomyopathies and Channelopathies • Rheumatic Heart Disease • Endocarditis • Cardiac Pharmacology • Transition From Pediatric to Adult-Centered C ­ ardiac Care

Common Cardiac I­ ssues in Pediatrics

Common Cardiac ­Issues in Pediatrics

Common Cardiac Issues in Pediatrics

Editors Jonathan N. Johnson, MD, FACC, FAAP Deepak M. Kamat, MD, PhD, FAAP

ISBN 978-1-61002-144-9

90000>

9 781610 021449

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AAP

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Common Cardiac Issues in Pediatrics

Editors Jonathan N. Johnson, MD, FACC, FAAP Deepak M. Kamat, MD, PhD, FAAP

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American Academy of Pediatrics Publishing Staff Mark Grimes, Vice President, Publishing Chris Wiberg, Senior Editor, Professional/Clinical Publishing Theresa Wiener, Production Manager, Clinical and Professional Publications Heather Babiar, Medical Copy Editor Peg Mulcahy, Manager, Art Direction and Production Mary Lou White, Chief Product and Services Officer/SVP, Membership, Marketing, and Publishing Mary Louise Carr, MBA, Marketing Manager, Clinical Publications 345 Park Blvd Itasca, IL 60143 Telephone: 630/626-6000 Facsimile: 847/434-8000 www.aap.org The recommendations in this publication do not indicate an exclusive course of treatment or serve as a standard of care. Variations, taking into account individual circumstances, may be appropriate. Listing of resources does not imply an endorsement by the American Academy of Pediatrics (AAP). The AAP is not responsible for the content of external resources. Information was current at the time of publication. Brand names are furnished for identification purposes only. No endorsement of the manufacturers or products mentioned is implied. Every effort has been made to ensure that the drug selection and dosages set forth in this text are in accordance with the current recommendations and practice at the time of publication. It is the responsibility of the health care professional to check the package insert of each drug for any change in indications and dosages and for added warnings and precautions. The publishers have made every effort to trace the copyright holders for borrowed material. If they have inadvertently overlooked any, they will be pleased to make the necessary arrangements at the first opportunity. This publication has been developed by the American Academy of Pediatrics. The authors, editors, and contributors are expert authorities in the field of pediatrics. No commercial involvement of any kind has been solicited or accepted in the development of the content of this publication. Disclosures: Dr Cannon disclosed a data safety monitoring board relationship with Medtronic. Dr Stockton disclosed speaker’s bureau relationships with Sanofi Genzyme and Shire. Every effort is made to keep Common Cardiac Issues in Pediatrics consistent with the most recent advice and information available from the American Academy of Pediatrics. Special discounts are available for bulk purchases of this publication. E-mail our Special Sales Department at [email protected] for more information. © 2018 American Academy of Pediatrics

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means—electronic, mechanical, photocopying, recording, or otherwise—without prior written permission from the publisher (locate title at http://ebooks. aappublications.org and click on © Get Permissions; you may also fax the permissions editor at 847/434-8780 or e-mail [email protected]). Printed in the United States of America 9-389/0418

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MA0857 ISBN: 978-1-61002-144-9 eBook: 978-1-61002-145-6 EPUB: 978-1-61002-237-8 Mobi: 978-1-61002-238-5 Library of Congress Control Number: 2017940294

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COMMON CARDIAC ISSUES IN PEDIATRICS

Editors Jonathan N. Johnson, MD, FACC, FAAP Associate Professor of Pediatrics Chair, Division of Pediatric Cardiology Department of Pediatric and Adolescent Medicine Mayo Clinic Rochester, MN

Deepak M. Kamat, MD, PhD, FAAP Professor of Pediatrics Vice Chair for Education The Carman and Ann Adams Department of Pediatrics Wayne State University Designated Institutional Official Children’s Hospital of Michigan Detroit, MI

Contributing Authors Sanjeev Aggarwal Professor of Pediatrics Division of Pediatric Cardiology Children’s Hospital of Michigan Wayne State University Detroit, MI Ch 8: Chest Pain

Huzaifa Ahmad, MBBS MBBS Class of 2018 The Aga Khan University Karachi, Pakistan Ch 14: Neonatal Screening for Heart Disease

Kiona Y. Allen, MD Assistant Professor of Pediatrics Northwestern University Feinberg School of Medicine Ann and Robert H. Lurie Children’s Hospital of Chicago Chicago, IL Ch 39: Neurodevelopmental and Psychosocial Outcomes in Children With Congenital Heart Disease Carolyn A. Altman, MD, FAAP Associate Chief, Pediatric Cardiology Professor, Pediatrics Baylor College of Medicine Texas Children’s Hospital Houston, TX Ch 31: Prevention of Bacterial Endocarditis Ch 33: Pericardial Diseases

Ahdi Amer, MD Associate Professor of Pediatrics The Carman and Ann Adams Department of Pediatrics Wayne State University School of Medicine Detroit, MI Ch 28: Vaccines for Patients With Cardiac Conditions

Heather Anderson, MD, FAAP Fellow Division of Pediatric Cardiology Mayo Clinic Rochester, MN Ch 19: Congenital Heart Lesions

Kristin Anton, RN, MSM, CPNP-AC Children’s Health Dallas, TX Ch 44: Pulmonary Hypertension Neha Bansal, MD Fellow Pediatric Cardiology Children’s Hospital of Michigan Detroit, MI Ch 8: Chest Pain

Dianna M. E. Bardo, MD, FSCCT, FNASCI Director, Body MRI Co-Director, 3D Innovation Lab Department of Medical Imaging Phoenix Children’s Hospital Clinical Professor of Radiology and Child Health University of Arizona Phoenix, AZ Ch 5: Chest Radiography Sarosh P. Batlivala, MD, MSCI, FAAP Associate Professor, Pediatric Cardiology Associate Program Director, Pediatric Cardiology Fellowship Director, Pediatric Fellowship Training Programs The Children’s Heart Center Blair E. Batson Hospital for Children University of Mississippi Medical Center Jackson, MS Ch 19: Congenital Heart Lesions

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COMMON CARDIAC ISSUES IN PEDIATRICS

Allison K. Black, MD Pediatric Cardiology Fellow University of Pittsburgh Pittsburgh, PA Ch 38: Autonomic Dysfunction

Jessica Bowman, MD Attending Pediatric Cardiologist Nationwide Children’s Hospital Assistant Professor of Pediatrics The Ohio State University Columbus, OH Ch 40: Lifestyle Counseling

Harold M. Burkhart, MD Professor and Chief Department of Surgery Division of Thoracic and Cardiovascular Surgery University of Oklahoma Health Sciences Center Oklahoma City, OK Ch 16: Office Care of the Child After Cardiac Surgery Ryan Butts, MD Assistant Professor of Pediatrics Division of Pediatric Cardiology University of Texas Southwestern UN Dallas, TX Ch 32: Myocarditis

Michael U. Callaghan, MD Associate Professor of Pediatrics Children’s Hospital of Michigan Detroit, MI Ch 27: Cardiotoxicity Among Survivors of Childhood Cancer

Bryan Cannon, MD, FACC, FHRS, FAAP Director, Pediatric Electrophysiology Director, Pediatric Cardiology Fellowship Program Associate Professor of Pediatrics Mayo Clinic Rochester, MN Ch 37: Cardiac Screening for Athletic Participation Chesney Castleberry, MD Assistant Professor, Pediatric Cardiology School of Medicine, Washington University in St Louis St Louis Children’s Hospital St Louis, MO Ch 22: Restrictive Cardiomyopathy

Kanupriya Chaturvedi, MD, FAAP Fellow, Pediatric Cardiology The Congenital Heart Collaborative University Hospitals, Rainbow Babies and Children’s Hospital Cleveland, OH Ch 36: Cardiac Screening Prior to ADHD Treatment

Sharon Chen, MD, MPH Clinical Assistant Professor Pediatric Heart Failure and Transplantation Lucile Packard Children’s Hospital at Stanford University Palo Alto, CA Ch 43: Cardiac Transplantation Devyani Chowdhury, MD, FAAP, FACC Director, Cardiology Care for Children Affiliate Faculty Children’s Hospital of Philadelphia Lancaster, PA Ch 14: Neonatal Screening for Heart Disease

Jason Cole, MD PGY-3 Pediatric Resident Nationwide Children’s Hospital/Ohio State University Columbus, OH Ch 40: Lifestyle Counseling Michael Colon, MD Clinical Associate Professor of Pediatrics Division of Pediatric Cardiology Albany Medical College Albany, NY Ch 29: Lyme Carditis

John Colquitt, MD, FAAP Assistant Professor of Pediatrics Division of Pediatric Cardiology Baylor College of Medicine Texas Children’s Hospital Houston, TX Ch 31: Prevention of Bacterial Endocarditis Bibhuti B. Das, MD, FAAP, FACC Pediatric Heart Failure and Transplant Cardiologist Joe DiMaggio Children’s Hospital Memorial Health Care Hollywood, FL Ch 44: Pulmonary Hypertension

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COMMON CARDIAC ISSUES IN PEDIATRICS

Pirooz Eghtesady, MD, PhD, FAAP Professor and Emerson Chair Department of Surgery Chief, Pediatric Cardiac Surgery Washington University in St Louis Co-Director of the Heart Center St Louis Children’s Hospital St Louis, MO Ch 15: Surgical Procedures for Congenital Heart Disease

Noelle Andrea V. Fabie, MD Medical Biochemical Fellow Division of Genetic, Genomic, and Metabolic Disorders Children’s Hospital of Michigan Detroit, MI Ch 17: Common Syndromes Associated With Cardiac Lesions Swati Garekar, BC Director, Pediatric Cardiology Program Fortis Hospital, Mulund Mumbai, India Ch 26: Acute Rheumatic Fever and Rheumatic Heart Disease

Bessey Geevarghese, DO Assistant Professor Northwestern University Feinberg School of Medicine Attending Physician, Division of Infectious Disease Ann and Robert H. Lurie Children’s Hospital of Chicago Chicago, IL Ch 25: Kawasaki Disease Miwa Geiger, MD Assistant Professor of Pediatrics Division of Pediatric Cardiology Director, Fetal Heart Program Icahn School of Medicine at Mount Sinai New York, NY Ch 41: Cardiac Pharmacology

Samuel S. Gidding, MD Cardiology Division Head Nemours Cardiac Center Professor of Pediatrics Sidney Kimmel Medical College of Thomas Jefferson University Wilmington, DE Ch 34: Dyslipidemia

Julie Glickstein, MD, FACC, FAAP Professor of Pediatrics at Columbia University Medical Center Director, Pediatric Cardiology Fellowship Program Department of Pediatrics/Division of Pediatric Cardiology Morgan Stanley Children’s Hospital of New York Presbyterian New York, NY Ch 12: Evaluation of the Neonate With Congenital Heart Disease David J. Goldberg, MD Assistant Professor Department of Pediatrics The Perelman School of Medicine at The University of Pennsylvania Division of Cardiology The Children’s Hospital of Philadelphia Philadelphia, PA Ch 7: Laboratory Studies Pooja Gupta, MD, FASE, FACC Assistant Professor of Pediatrics Division of Pediatric Cardiology Children’s Hospital of Michigan Wayne State University Detroit, MI Ch 9: Syncope

Caitlin Haxel, MD Chief Fellow, Pediatric Cardiology Division of Pediatric Cardiology New York Presbyterian—Morgan Stanley Children’s Hospital Columbia University College of Physicians and Surgeons New York, NY Ch 12: Evaluation of the Neonate With Congenital Heart Disease Gurumurthy Hiremath, MD, FACC Assistant Professor of Pediatrics Division of Pediatric Cardiology University of Minnesota Minneapolis, MN Ch 1: Clinical History and Physical Examination Ch 11: Heart Murmur Whitnee Hogan, MD Pediatric Cardiology Fellow Department of Pediatrics University of Utah Salt Lake City, UT Ch 20: Hypertrophic Cardiomyopathy

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COMMON CARDIAC ISSUES IN PEDIATRICS

Kelley K. Hutchins, DO, MPH Pediatric Hematology/Oncology Fellow Children’s Hospital of Michigan Detroit, MI Ch 27: Cardiotoxicity Among Survivors of Childhood Cancer

Anitha S. John, MD, PhD Director, Washington Adult Congenital Heart Program Children’s National Medical Center and Washington Hospital Center Assistant Professor of Pediatrics George Washington University Washington, DC Ch 18: Adults With Congenital Heart Disease Jonathan N. Johnson, MD, FACC, FAAP Associate Professor of Pediatrics Chair, Division of Pediatric Cardiology Department of Pediatric and Adolescent Medicine Mayo Clinic Rochester, MN Ch 4: Basics of Exercise Testing

Joyce Johnson, MD, MS, FAAP Assistant Professor, Pediatric Cardiology Ann & Robert H. Lurie Children’s Hospital of Chicago Northwestern University Feinberg School of Medicine Chicago, IL Ch 19: Congenital Heart Lesions

Beth D. Kaufman, MD Clinical Associate Professor of Pediatrics Director, Pediatric Cardiomyopathy Program Lucile Packard Children’s Hospital, Stanford University Palo Alto, CA Ch 43: Cardiac Transplantation Angela M. Kelle, MD, FACC, FAAP Assistant Professor of Pediatrics Penn State Children’s Hospital Hershey, PA Ch 3: The Role of Echocardiography

Steven J. Kindel, MD Assistant Professor of Pediatrics Medical Director of Advanced Heart Failure and Heart Transplantation Herma Heart Center Children’s Hospital of Wisconsin Medical College of Wisconsin Milwaukee, WI Ch 23: Noncompaction Cardiomyopathy

Sonya Kirmani, MD Instructor, Pediatric Heart Failure/Transplant Division of Pediatric Cardiology Duke University Medical Center Durham, NC Ch 22: Restrictive Cardiomyopathy

Stacie Knutson, MD Assistant Professor of Pediatrics Division of Pediatric Cardiology University of Minnesota Minneapolis, MN Ch 1: Clinical History and Physical Examination Ch 11: Heart Murmur William Buck Kyle, MD, FAAP Assistant Professor of Pediatrics Division of Pediatric Cardiology Baylor College of Medicine/Texas Children’s Hospital Houston, TX Ch 19: Congenital Heart Lesions Timothy S. Lancaster, MD Fellow in Cardiothoracic Surgery Barnes-Jewish/St Louis Children’s Hospitals Washington University School of Medicine St Louis, MO Ch 15: Surgical Procedures for Congenital Heart Disease Diego Lara, MD, MPH Pediatric and Fetal Cardiology Ochsner Hospital for Children Senior Lecturer University of Queensland-Ochsner Clinical School New Orleans, LA Ch 33: Pericardial Diseases Shannon Lyon, DO University of Louisville Department of Pediatrics Louisville, KY Ch 21: Dilated Cardiomyopathy

Nicolas L. Madsen, MD, MPH Medical Director, Inpatient Cardiology Assistant Professor of Pediatrics University of Cincinnati College of Medicine Cincinnati Children’s Hospital Medical Center Cincinnati, OH Ch 19: Congenital Heart Lesions

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COMMON CARDIAC ISSUES IN PEDIATRICS

Bradley S. Marino, MD, MPP, MSCE, FAAP Professor Pediatrics and Medical Social Sciences Northwestern University Feinberg School of Medicine Heart Center Co-Director, Research and Academic Affairs Divisions of Cardiology and Critical Care Medicine Ann & Robert H. Lurie Children’s Hospital of Chicago Chicago, IL Ch 39: Neurodevelopmental and Psychosocial Outcomes in Children With Congenital Heart Disease Daniel Mauriello, MD Assistant Professor of Pediatrics Division of Pediatric Cardiology Johns Hopkins All Children’s Hospital St Petersburg, FL Ch 2: Electrocardiography

Shaji C. Menon, MD, FACC, FASE, FAAP Associate Professor of Pediatrics Adjunct Associate Professor of Radiology Medical Director, Single Ventricle Survivorship Program University of Utah Salt Lake City, UT Ch 6: Cardiac MR Imaging and CT James H. Moller, MD, FAAP Professor Emeritus and Former Head of Pediatrics Adjunct Professor of Pediatrics Minneapolis, MN Ch 13: Fetal and Newborn Transitional Circulations Brandon Morrical, MD, FAAP Instructor of Pediatrics Division of Pediatric Cardiology Mayo Clinic Rochester, MN Ch 4: Basics of Exercise Testing

Kathleen A. Mussatto, PhD, RN Co-Director of Cardiac Research Associate Clinical Professor of Surgery Children’s Hospital of Wisconsin Milwaukee, WI Ch 39: Neurodevelopmental and Psychosocial Outcomes in Children With Congenital Heart Disease

Mark D. Norris, MD, MS Medical Co-Director Adult Congenital Heart Program University of Michigan Ann Arbor, MI Ch 42: Transition and Transfer From Pediatric to Adult-Centered Cardiac Care Todd T. Nowlen, MD, FACC Director Ambulatory Cardiology Phoenix Children’s Hospital Phoenix, AZ Ch 5: Chest Radiography

Brandon Lane Phillips, MD, FAAP Department of Pediatrics Ochsner Health Center for Children Monroe, Ochsner Clinic Foundation West Monroe, LA Ch 1: Clinical History and Physical Examination

Adam Putschoegl, DO, FAAP Pediatric Cardiology Fellow Division of Pediatric Cardiology Mayo Clinic Rochester, MN Ch 19: Congenital Heart Lesions Ch 42: Transition and Transfer From Pediatric to Adult-Centered Cardiac Care Muhammad Yasir Qureshi, MBBS, FASE Senior Associate Consultant Pediatric Cardiology Assistant Professor of Pediatrics Mayo Clinic College of Medicine Rochester, MN Ch 3: The Role of Echocardiography

Hari Rajagopal, MD Pediatric Cardiology Advanced Imaging Fellow Division of Pediatric Cardiology Icahn School of Medicine at Mount Sinai New York, NY Ch 41: Cardiac Pharmacology Rini Sahewalla, MD Fellow, Pediatric Cardiology Children’s Hospital of Michigan Detroit, MI Ch 17: Common Syndromes Associated With Cardiac Lesions

Amy H. Schultz, MD, MSCE, FACC, FAAP Attending Cardiologist Seattle Children’s Hospital Associate Professor of Pediatrics Division of Cardiology University of Washington School of Medicine Seattle, WA Ch 30: Endocarditis vii

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COMMON CARDIAC ISSUES IN PEDIATRICS

Kristen Sexson Tejtel, MD, PhD, MPH, FAAP Assistant Professor of Pediatrics Director, Center for Preventive Cardiology Texas Children’s Hospital Baylor College of Medicine Houston, TX Ch 35: Hypertension

Stanford T. Shulman, MD, FAAP Virginia H. Rogers Professor of Pediatric Infectious Diseases Northwestern University Feinberg School of Medicine Division Head Emeritus Infectious Diseases Ann and Robert H. Lurie Children’s Hospital of Chicago Chicago, IL Ch 25: Kawasaki Disease Nikki M. Singh, MD Pediatric Cardiology Fellow Medical College of Wisconsin Children’s Hospital of Wisconsin Milwaukee, WI Ch 23: Noncompaction Cardiomyopathy

Lalitha Sivaswamy, MD Associate Professor of Pediatrics and Neurology Carmen and Ann Adams Department of Pediatrics Wayne State University School of Medicine Detroit, MI Ch 9: Syncope Melissa Smith-Parrish, MD Assistant Professor of Pediatrics Northwestern University Feinberg School of Medicine Chicago, IL Ch 39: Neurodevelopmental and Psychosocial Outcomes in Children With Congenital Heart Disease Brian S. Snarr, MD, PhD Cardiology Fellow Division of Cardiology The Children’s Hospital of Philadelphia Philadelphia, PA Ch 7: Laboratory Studies

Christopher Snyder, MD, FAAP Ch 36: Cardiac Screening Prior to ADHD Treatment

Joshua D. Sparks, MD Director, Pediatric Advanced Heart Failure and Transplantation University of Louisville School of Medicine Norton Children’s Hospital Louisville, KY Ch 21: Dilated Cardiomyopathy Ch 38: Autonomic Dysfunction

Rachel Steury, MSN, CNP Washington, Adult Congenital Heart Program Children’s National Health System Washington, DC Ch 18: Adults With Congenital Heart Disease

David W. Stockton, MD, FACMG Professor of Pediatrics and Internal Medicine Chief, Division of Genetic, Genomic and Metabolic Disorders Wayne State University and Children’s Hospital of Michigan Detroit, MI Ch 17: Common Syndromes Associated With Cardiac Lesions Alex J. Thompson, MD, FAAP Department of Pediatric and Adolescent Medicine Division of Pediatric Cardiology Mayo Clinic Rochester, MN Ch 19: Congenital Heart Lesions

Jess Thompson, MD, MSc Assistant Professor of Surgery Section of Congenital Heart Surgery University of Oklahoma Oklahoma City, OK Ch 16: Office Care of the Child After Cardiac Surgery

Bhadra Trivedi, MD Pediatrics, Fellow, Pediatric Cardiology Department of Pediatric Cardiology Fortis Child Heart Mission Fortis Hospital Mulund Mumbai, India Ch 26: Acute Rheumatic Fever and Rheumatic Heart Disease Juan Villafañe, MD, FAAP Professor of Pediatrics Cardiology University of Kentucky Lexington, KY Ch 24: Long QT Syndrome and Other Channelopathies

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COMMON CARDIAC ISSUES IN PEDIATRICS

Philip L. Wackel, MD Assistant Professor of Pediatrics Division of Pediatric Cardiology Mayo Clinic College of Medicine Rochester, MN Ch 10: Palpitations and Arrhythmia

Josh Weldin, MD Assistant Professor of Pediatrics Division of Pediatric Cardiology University of Washington School of Medicine Seattle Children’s Hospital Seattle, WA Ch 30: Endocarditis

Melissa Yamauchi, MD, MPH University of Utah Salt Lake City, UT Ch 6: Cardiac MR Imaging and CT

American Academy of ­Pediatrics Reviewers Section on Cardiology and Cardiac Surgery Section on Clinical Pharmacology and Therapeutics Section on Infectious Diseases Section on Medicine—Pediatrics

Don P. Wilson, MD, FNLA Diplomate, American Board of Clinical Lipidology Endowed Chair, Pediatric Cardiovascular Health and Risk Prevention Pediatric Endocrinology and Diabetes Cook Children’s Medical Center Fort Worth, TX Ch 34: Dyslipidemia

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Contents Introduction.......................................................................................... xvii

Part 1: Evaluation of the Patient 1. Clinical ­History and Physical ­Examination.......................................... 3 Brandon Lane Phillips, MD, FAAP, Stacie Knutson, MD, and Gurumurthy Hiremath, MD, FACC

2. Electrocardiography........................................................................... 13 Daniel Mauriello, MD 3. The Role of ­Echocardiography............................................................ 49 Angela M. Kelle, MD, FACC, FAAP, and Muhammad Yasir Qureshi, MBBS, FASE 4. Basics of Exercise Testing................................................................... 71 Brandon Morrical, MD, FAAP, and Jonathan N. Johnson, MD, FACC, FAAP 5. Chest Radiography............................................................................. 79 Todd T. Nowlen, MD, FACC, and Dianna M. E. Bardo, MD, FSCCT, FNASCI 6. Cardiac MR ­Imaging and CT............................................................. 95 Melissa Yamauchi, MD, MPH, and Shaji C. Menon, MD, FACC, FASE, FAAP

7. Laboratory Studies........................................................................... 109 Brian S. Snarr, MD, PhD, and David J. Goldberg, MD

Part 2: Common Signs and Symptoms 8. Chest Pain....................................................................................... 117 Neha Bansal, MD, and Sanjeev Aggarwal, MD 9. Syncope........................................................................................... 133 Lalitha Sivaswamy, MD, and Pooja Gupta, MD, FASE, FACC

10. Palpitations and ­Arrhythmia............................................................. 147 Philip L. Wackel, MD 11. Heart Murmur................................................................................. 161 Gurumurthy Hiremath, MD, FACC, and Stacie Knutson, MD

12. Evaluation of the Neonate With ­Congenital Heart Disease................ 171 Caitlin Haxel, MD, and Julie Glickstein, MD, FACC, FAAP

xi

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CONTENTS

Part 3: Congenital Heart Disease 13. Fetal and ­Newborn Transitional ­Circulations..................................... 187 James H. Moller, MD, FAAP

14. Neonatal Screening for Heart Disease............................................... 197 Huzaifa Ahmad, MBBS, and Devyani Chowdhury, MD, FAAP, FACC 15. Surgical Procedures for Congenital Heart Disease............................. 205 Timothy S. Lancaster, MD, and Pirooz Eghtesady, MD, PhD, FAAP 16. Office Care of the Child After Cardiac Surgery.................................. 237 Jess Thompson, MD, MSc, and Harold M. Burkhart, MD

17. Common ­Syndromes ­Associated With Cardiac Lesions..................... 245 Noelle Andrea Fabie, MD, Rini Sahewalla, MD, and David W. Stockton, MD, FACMG 18. Adults With ­Congenital Heart Disease............................................. 269 Rachel Steury, MSN, CNP, and Anitha S. John, MD, PhD 19. Congenital Heart Lesions................................................................. 287

Aortic Valve ­Problems, ­Including Bicuspid Aortic Valve and ­Subaortic Membranes................................................................ 287 William Buck Kyle, MD, FAAP Atrial Septal Defects........................................................................ 292 Alex J. Thompson, MD, FAAP, and Nicolas L. Madsen, MD, MPH

Atrioventricular Canal Defects......................................................... 296 Sarosh P. Batlivala, MD, MSCI, FAAP

Coarctation of the Aorta................................................................... 300 Sarosh P. Batlivala, MD, MSCI, FAAP “Congenitally ­Corrected” ­Transposition of the Great ­Arteries............ 305 Sarosh P. Batlivala, MD, MSCI, FAAP Mitral Valve Anomalies.................................................................... 308 Joyce Johnson, MD, MS, FAAP

Patent Ductus Arteriosus.................................................................. 311 Joyce Johnson, MD, MS, FAAP Patent Foramen Ovale...................................................................... 314 William Buck Kyle, MD, FAAP Pulmonary Stenosis.......................................................................... 316 Heather Anderson, MD, FAAP, and Nicolas Madsen, MD, MPH, FAAP

xii

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CONTENTS



Single-Ventricle Lesions................................................................... 320 Joyce Johnson, MD, MS, FAAP Systemic and Pulmonary Vein Anomalies.......................................... 325 Joyce Johnson, MD, MS, FAAP

Tetralogy of Fallot............................................................................ 329 Nicolas L. Madsen, MD, MPH Transposition of the Great Arteries................................................... 334 William Buck Kyle, MD, FAAP Tricuspid Valve Anomalies................................................................ 339 William Buck Kyle, MD, FAAP Truncus Arteriosus........................................................................... 343 Adam Putschoegl, DO, FAAP Vascular Rings and Slings................................................................. 347 Sarosh P. Batlivala, MD, MSCI, FAAP Ventricular Septal Defects................................................................ 353 Sarosh P. Batlivala, MD, MSCI, FAAP

Part 4: C ­ ardiomyopathies and ­Channelopathies 20. Hypertrophic ­Cardiomyopathy......................................................... 361 Whitnee Hogan, MD, and Shaji C. Menon, MD, FACC, FASE, FAAP

21. Dilated ­Cardiomyopathy.................................................................. 377 Shannon Lyon, DO, and Joshua D. Sparks, MD

22. Restrictive ­Cardiomyopathy.............................................................. 387 Chesney Castleberry, MD, and Sonya Kirmani, MD 23. Noncompaction Cardiomyopathy...................................................... 395 Nikki M. Singh, MD, and Steven J. Kindel, MD 24. Long QT S ­ yndrome and Other ­Channelopathies.............................. 411 Juan Villafañe, MD, FAAP

Part 5: Acquired Cardiac Diseases 25. Kawasaki Disease............................................................................. 423 Bessey Geevarghese, DO, and Stanford T. Shulman, MD, FAAP

26. Acute ­Rheumatic Fever and ­Rheumatic Heart Disease....................... 443 Swati Garekar, BC, and Bhadra Trivedi, MD 27. Cardiotoxicity Among Survivors of Childhood Cancer....................... 463 Kelley K. Hutchins, DO, MPH, and Michael U. Callaghan, MD xiii

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CONTENTS

Part 6: Infectious Diseases 28. Vaccines for ­Patients With ­Cardiac Conditions ................................. 477 Ahdi Amer, MD

29. Lyme Carditis.................................................................................. 487 Michael Colon, MD 30. Endocarditis.................................................................................... 497 Amy H. Schultz, MD, MSCE, FAAP, FACC, and Josh Weldin, MD 31. Prevention of ­Bacterial ­Endocarditis................................................. 511 John Colquitt, MD, FAAP, and Carolyn A. Altman, MD, FAAP

32. Myocarditis...................................................................................... 517 Ryan Butts, MD 33. Pericardial Diseases.......................................................................... 529 Diego Lara, MD, MPH, and Carolyn A. Altman, MD, FAAP

Part 7: Preventive C ­ ardiology 34. Dyslipidemia.................................................................................... 545 Don P. Wilson, MD, FNLA, and Samuel S. Gidding, MD 35. Hypertension................................................................................... 567 S. Kristen Sexson Tejtel, MD, PhD, MPH, FAAP

36. Cardiac ­Screening Prior to ADHD Treatment................................... 595 Kanupriya Chaturvedi, MD, FAAP, and Christopher Snyder, MD, FAAP 37. Cardiac ­Screening for Athletic ­Participation...................................... 603 Bryan Cannon, MD, FACC, FHRS 38. Autonomic ­D ysfunction................................................................... 613 Alison Black, MD, and Joshua D. Sparks, MD

Part 8: General Issues in Primary Cardiac Care 39. Neurodevelopmental and ­Psychosocial ­Outcomes in ­Children With ­Congenital Heart Disease................................................................. 627 Kiona Y. Allen, MD, Melissa Smith-Parrish, MD, Kathleen A. Mussatto, PhD, RN, and Bradley S. Marino, MD, MPP, MSCE, FAAP 40. Lifestyle ­Counseling......................................................................... 643 Jessica Bowman, MD, and Jason Cole, MD 41. Cardiac ­Pharmacology...................................................................... 655 Miwa Geiger, MD, and Hari Rajagopal, MD xiv

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CONTENTS

42. Transition and Transfer From ­Pediatric to Adult-Centered Cardiac Care.................................................................................... 685 Mark D. Norris, MD, MS, and Adam Putschoegl, DO, FAAP

Part 9: Special Conditions 43. Cardiac ­Transplantation................................................................... 701 Sharon Chen, MD, MPH, and Beth D. Kaufman, MD 44. Pulmonary ­Hypertension................................................................. 713 Kristin Anton, RN, MSN, CPNP-AC, and Bibhuti B. Das, MD, FAAP, FACC Index..................................................................................................... 727

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Introduction Though heart defects in children had been studied for many years, the field of pediatric cardiology was essentially born in the 1930s, when Robert Gross performed the first surgical ligation of a patent ductus arteriosus. Instead of cardiac defects being a pathologic entity seen at autopsy, they became treatable. Helen Taussig began training pediatricians in the new field of pediatric cardiology in the late 1940s, and pediatric cardiology became the first sub-board of pediatrics in 1961. The Section on Cardiology of the American Academy of Pediatrics (AAP) was formed in 1955. The field of pediatric cardiology has seen incredible advances in its short period of existence. Cardiopulmonary bypass, used to repair intracardiac defects, was first successfully used in children in 1954 and 1955. The first echocardiograms, initially 1-dimensional, were reported in 1953, but 2-dimensional images of the moving heart were not available until the early 1970s. The arterial switch procedure, now the standard of care for most patients with transposition of the great arteries, was first performed in 1975—only 43 years ago. As these advances in pediatric cardiac care have occurred, the scope of pediatric primary care exposure to patients with complex cardiac anatomy has increased. This text was created specifically for the pediatric care professional (pediatrician, family physician, nurse practitioner, physician assistant, and all trainees and students) who could see a patient in the inpatient or outpatient setting with heart disease. The content starts with the fundamentals of history and physical examination, followed by the basics of cardiac testing, including electrocardiography, echocardiography, and chest radiography. Specific chapters focus on common symptoms, such as chest pain, syncope, and murmurs. Extensive guidance is provided for each type of congenital lesion a patient may present with in your office—each easily looked up and reviewed quickly just prior to seeing a patient. Acquired diseases such as Kawasaki disease are discussed, as well as infectious diseases, such as rheumatic fever, Lyme disease, endocarditis, pericarditis, and myocarditis. Common preventive cardiology issues are presented, including dyslipidemia, hypertension, sports clearance, screening prior to attention-deficit/hyperactivity disorder medication administration, and adolescent autonomic dysfunction. Finally, a robust discussion of cardiac medications is provided, focused on the pediatric care professional. In assembling this book, we have capitalized on the rich and unique resources of the American Academy of Pediatrics (AAP), as well as contributions from experts from around the globe. We thank all of our authors for their time and expertise. The contents of this book were reviewed by experts from relevant AAP sections, committees, and councils, including non–cardiology specialty perspectives. The editors and contributing authors are grateful for these reviewers’ expertise and generous feedback. Special thanks are due to the cardiologists xvii

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INTRODUCTION

and cardiac surgeons of the Publications and Communications Workgroup of the Section on Cardiology and Cardiac Surgery, who personally reviewed every chapter. We want to give our sincere thanks to Chris Wiberg at the AAP, who was the senior editor for this book. We appreciate his commitment to the project, his editorial prowess, his constant encouragement, and his collaborative spirit. Finally, we want to thank our families for their love, understanding, and support while we took on this amazing endeavor. This book is focused on the pediatric care professional for a specific reason: You are essential partners with families and cardiology teams in the care of these children. We hope this book will help answer questions that arise on a daily basis and serve as an essential resource in your office, with the ultimate goal of improving care for all children with heart disease.

Jonathan N. Johnson, MD, FACC, FAAP Deepak Kamat, MD, PhD, FAAP

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PART 1

Evaluation of the Patient 1. Clinical ­History and Physical ­Examination............................... 3 2. Electrocardiography...................................................................13 3. The Role of ­Echocardiography..................................................49 4. Basics of Exercise Testing..........................................................71 5. Chest Radiography....................................................................79 6. Cardiac MR ­Imaging and CT...................................................95 7. Laboratory Studies................................................................. 109

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CHAPTER 1

Clinical ­History and Physical ­Examination Brandon Lane Phillips, MD, FAAP, Stacie Knutson, MD, and Gurumurthy Hiremath, MD, FACC

Introduction The history and physical examination are the first and most important steps in the evaluation of any child for whom there is a concern for heart disease. A thorough history is essential when evaluating children who present with common cardiac concerns, such as syncope and chest pain. Often, the history will contain important clues that an astute clinician will use to guide medical decision-making and management. A thorough physical examination can also play a role in helping to establish the correct diagnosis without the need for expensive ancillary tests. This chapter will address the basics of the cardiac history and physical examination in children.

History A thorough history—including a detailed personal history of the child, history of the mother during pregnancy, the child’s birth history, past medical history, review of systems, family history, and social history—should be obtained. The maternal history should include assessment of complications during pregnancy or delivery and assessment of any teratogenic exposures during pregnancy. In all patients, the timing of appearance of signs and symptoms should be clearly delineated, because 3

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this can often help establish a differential diagnosis. Specific details of the personal cardiac history can vary, depending on the age of the child.

Infants The largest energy expenditure in infants is feeding, and infants with congenital heart disease (CHD) or heart failure commonly present with symptoms during feeding. Infants may ingest less breast milk or formula per feeding than usual, or their symptoms may arise only during feeding, including sweatiness, tachypnea, fussiness, and irritability. In infants with heart failure, the volume of feedings has been shown to be the most sensitive variable historically associated with clinical heart failure. Poor growth may be present, particularly in patients with large left-to-right shunts or heart failure.

Young Children Symptoms in young children can be subtle, because children can compensate very well despite having clinically significant CHD or poor heart function. Patients and their parents should be asked about any chest pain, palpitations, or fainting spells. A chronic cough may be present if pulmonary congestion or bronchial compression is present. Abdominal pain, nausea, or anorexia may be present in children with heart failure because of poor cardiac output to peripheral tissues. Because parents often find it difficult to know what “normal” exercise ability is for a young child, it can be helpful to ask what his or her ability level is in comparison to other children or older siblings.

Adolescents Although older children and adolescents may present with symptoms similar to those of younger children, they may also complain of symptoms similar to those of adults. Patients should be asked about any chest pain, palpitations, dizziness or fainting spells, and changes in exercise tolerance. Patients should also be asked about any of these symptoms occurring with exertion. Additionally, patients should be asked about snoring and whether they have any symptoms of orthopnea.

Past Medical History Obtaining a thorough past medical history is important to ensure that no other medical conditions are present that may place the patient at risk for cardiac disease. Particular attention should be given to any history of genetic syndromes or chromosomal abnormalities. Patients with connective tissue disorders may report a history of pneumothorax, easy joint dislocation, or lens dislocation. Patients should be asked about a history of Kawasaki disease and rheumatic heart fever, particularly if they are from a geographic area or have an ethnic background endemic to either condition. A history of previous fainting episodes 4

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and seizures and a family history should be obtained when there is concern that the patient’s syncopal episode may be caused by a genetic mutation, such as long QT syndrome.

Family History Patients and their parents should be asked about any family history of CHD, cardiomyopathy, hyperlipidemia, hypertension, or early coronary artery disease (manifesting before the age of 50 years). Any history of sudden, unexplained death should be obtained, including unexplained car accidents, drownings, seizures, or sudden infant death syndrome. It is most important to obtain this history for first- and second-degree family members.

History Compilation Techniques In older children, it is important to engage the patient directly in the history compilation process, since he or she is the one experiencing the symptoms. In a child who has undergone a prior surgical repair of CHD, history compilation is an opportunity to assess the child’s knowledge about his or her own health condition. Precision is also important in the history compilation process. Terms such as “heart attack” and “passing out” need to be clarified to make sure that parents and practitioners are using the same definitions.

Physical Examination Assessment of Vital Signs Heart rate, respiratory rate, oxygen saturation, and blood pressure should be assessed at each visit. An abnormal heart rate can alert the clinician to a diagnosis of congestive heart failure or even a noncardiac disorder, such as thyroid dysfunction or Lyme disease with heart block. In addition to physical palpation of the pulse in the upper and lower extremities, blood pressure measurements should be obtained in the upper and lower extremities during the first visit to assess the patient for coarctation of the aorta. Oxygen saturation should be recorded in all patients. In patients who underwent a previous cardiac surgery, oxygen saturation should be followed serially, and results should be compared to those obtained at previous clinical encounters. It is important to remember that blood pressure should be assessed with the patient calm and sitting down. The use of an inappropriately sized blood pressure cuff remains the most common cause of inaccurate hypertension diagnoses in children. The length of the bladder of the cuff should be 80% of the circumference of the limb being measured, and the width of the cuff should cover two-thirds of the length of the extremity. 5

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Inspection A considerable degree of information can be obtained with observation. The physician should determine if the child is in any distress, is over- or undernourished, or has any potential genetic syndrome. Cyanosis can be indicative of CHD but can be difficult to detect in patients with anemia or dark skin pigmentation. Special attention should be given to the tongue, nail beds, and conjunctiva. Acrocyanosis may be seen in healthy infants, where the hands and feet have a blue hue but the remainder of the skin is normal. Digital clubbing can be seen in the fingernails and toenails of a patient with prolonged desaturation. The respiratory rate and presence of any retractions should be noted. The chest should be inspected to look for any pectus abnormalities (excavatum or carinatum) or asymmetry of the chest.

Palpation Palpation of the peripheral pulse should be performed, including the pulse in both upper and lower extremities. A weak leg pulse relative to that of the arm suggests coarctation of the aorta. A bounding pulse (widened pulse pressure) may be found in a patient with patent ductus arteriosus, aortic regurgitation, or arteriovenous fistula. Palpation of the chest should be performed to identify the apical impulse and to look for evidence of a hyperactive precordium and thrills. After the age of 10 years, the apical impulse is typically located at the midclavicular line in the fifth intercostal space. An apical impulse that is displaced laterally or downward suggests cardiomegaly. A hyperactive precordium is associated with large left-to-right shunts. Thrills are palpable vibratory sensations associated with harsh murmurs. Thrills may be felt on the chest wall or in the suprasternal notch in the setting of clinically significant aortic stenosis. Palpation of the abdomen should be performed to assess the size and texture or consistency of the liver and spleen. With increased venous pressure or increasing shunt volume, the liver will become enlarged. Percussion of the liver may be performed in older children and adolescents.

Auscultation To diagnose a cardiac murmur, it is necessary to understand and describe the heart sound in the context of the cardiac cycle. The cardiac cycle can be broken down into systole and diastole (Figure 1-1). Systole is the period of ventricular contraction during which blood is ejected from the right ventricles (RVs) and left ventricles (LVs) into the main pulmonary artery and aorta, respectively. Diastole is the period of ventricular relaxation during which tricuspid and mitral valves are open and the ventricles fill with blood from the atria. Most of the blood enters the ventricles passively, but a small portion is ejected during atrial contraction that occurs in late diastole. At the onset of systole, the ventricles 6

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FIGURE 1-1. The cardiac cycle. AV = atrioventricular. From https://courses.lumenlearning.com/ap2/ chapter/cardiac-cycle/.

contract, causing a rapid increase in ventricular pressure that soon exceeds the atrial pressure. Once the pressure within the ventricles exceeds that of the atria, the tricuspid and mitral valves are forced closed. Closure of these valves produces the first heart sound (S1). The ventricular pressures continue to rise with contraction during a phase called isovolumetric contraction until they exceed that of the pulmonary artery and aorta. This results in opening of the pulmonic and aortic valves and ejection of blood from the ventricles (ejection phase). As the ejection of blood is completed, the ventricular pressure begins to decrease. Once ventricular pressure falls below that of the main pulmonary artery and aorta, the pulmonic and aortic valves are forced closed, producing the second heart sound (S2). The ventricular pressure decreases rapidly as a result of the ventricular relaxation during a phase called isovolumetric relaxation. Once the ventricular pressure falls below that of the atria, the tricuspid and mitral valves open, allowing passive filling of blood into the ventricles, and the cycle repeats. Being able to accurately identify the first and the second heart sounds (S1 and S2, respectively) will allow for categorization of murmurs and extra heart sounds on the basis of the phase of the cardiac cycle within which they occur (systole or diastole). Both S1 and S2 are composed of 2 components, each of which can be heard by the trained ear. The mitral valve closes slightly before the tricuspid 7

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valve because of normal nonsynchronous contraction of the ventricles, with the LV beginning and ending the contraction prior to the RV. The splitting of S1 is generally not appreciated because of the minimal time difference between when the mitral and tricuspid valves close. S2 is composed of P2 and A2, which represent closure of the pulmonic and aortic valves, respectively. Normally, the aortic valve closes slightly before the pulmonic valve, but because it is in close proximity, it can be difficult to differentiate the 2 sounds. Physiological splitting of S2 occurs throughout the respiratory cycle. With inspiration, there is increased blood return to the right atrium and therefore the RV. This increased blood volume results in an increase in the ejection time from the RV. Therefore, the pulmonic valve remains open longer and accentuates the time difference between closure of the aortic and pulmonic valves, which is heard as splitting of the S2. During expiration, A2 and P2 occur almost simultaneously, as mentioned earlier, and are heard as a single S2. In addition to S1 and S2, on occasion 2 other sounds, called S3 and S4, can be heard (audio available at www.youtube.com/watch?v=DxMnm5C5PW8&index= 1&list=PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu)( ). Both of these sounds occur during diastole. S3 occurs during early diastole as a result of rapid filling of the ventricle after opening of the tricuspid and mitral valves. This is generally a normal sound in children but can indicate volume overload. S4 occurs during late diastole and coincides with atrial contraction. When the atria contract and eject blood into a stiffened ventricle, S4 is produced.



Physiology of Cardiac Murmurs There are 4 main locations that are used for auscultation, which correspond to the 4 cardiac valves (Figure 1-2). The aortic area is located at the second to third intercostal space to the right of the sternum (right upper sternal border). The pulmonic area is located at the second to third intercostal space to the left of the sternum (left upper sternal border). The tricuspid area is at the left lower sternal border, and the mitral area is located at the apex of the heart. As described previously, S1 is the closure of the tricuspid and mitral valves, and it can be best heard at the apex. S2 and splitting of the S2 are best heard at the left upper sternal border in the pulmonic area. S3 and S4 are best heard at the apex or the left lower sternal border, depending on whether they are originating from the LV or the RV. When a murmur is heard, it is important to be able to localize the sound to a specific area of the heart and to characterize the murmur. The key components of characterizing a murmur are timing, intensity, pitch, quality, location, radiation, positional variation, and presence of extra heart sounds. The first step is to identify S1 and S2. Once these are identified, the timing of the murmur in the cardiac cycle can be defined as ejection systolic, holosystolic, diastolic, or continuous. Systolic murmurs occur after S1, and diastolic murmurs occur 8

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Clinical ­History and Physical E ­ xamination

Right Infraclavicular Area PPS (S) Venoushum (C)

Suprasternal Notch AS/supravalvar AS (S)

Right Upper Sternal Border (“aortic area”) Aortic stenosis (valvar, supravalvar) (S) PPS (S)

Left Lower Sternal Border (“tricuspid area”) Still’s murmur (S) VSD (S) TR (S) TS (D) TS—functional (with ASD) (D) PR (D)

Left Upper Sternal Border (“pulmonary area”) PS and ejection click (S) Normal pulmonary flow (S) PDA (C)

1

Left MH Sternal Border Innocent flow (S) PS, AS, sub PS/AS (S) Aortic pulm. Ej. click (S) VSD (S) AR/PR (D)

Left Infraclavicular Area PPS (S) Coarctation of the aorta (better noted left subscapular) (S) PDA (C)

2 3

Apex (“mitral area”) Still’s murmur (S) MR (S) Ejection click of AS (S) Coarctation of the aorta (S) AR (D) MS (D) MS—functional (with VSD) (D)

4 5 6 7 8 9 10

S  systolic D  dystolic C  continuous Lateral Chest/Axilla PPS (also heard in midback) (S) MR radiation (S)

FIGURE 1-2. Typical location or listening areas for murmurs. AR = aortic regurgitation, AS = aortic stenosis, ASD = atrial septal defect, MR = mitral regurgitation, MS = mitral stenosis, PDA = patent ductus arteriosus, PPS = peripheral pulmonic stenosis, PR = pulmonary regurgitation, PS = pulmonary stenosis, TR = tricuspid regurgitation, TS = tricuspid stenosis, VSD = ventricular septal defect. From Koenig P, Hijazi Z, Zimmerman F. Essential Pediatric Cardiology. New York, NY: McGraw Hill; 2004.

after S2. Holosystolic murmurs occur at the onset of systole and result in the obliteration of S1. The presence of a holosystolic murmur indicates that blood is escaping from the ventricle as soon as ventricular contraction begins. This can be caused by a ventricular septal defect or tricuspid or mitral valve regurgitation. An ejection systolic murmur, however, begins after S1 (during the ejection phase) and is usually caused by ventricular outflow tract obstruction. With an ejection systolic murmur, S1 can be defined, whereas with a holosystolic murmur, S1 is incorporated into the murmur and cannot be defined. Continuous murmurs are present throughout systole and diastole. (See the list of Audio Recordings of heart murmurs at the end of this chapter.)( ) Systolic and diastolic murmurs each have their own intensity classification. Systolic murmurs are graded I to VI, whereas diastolic murmurs are graded I to IV. The initial classification of systolic heart murmurs was the Levine system. Owing to the subjective nature of this system for murmurs graded III or VI or less, a variation may be used in which the patient’s own heart sounds are used as an internal reference for grading.1 By using this system, grade I murmurs are less intense than the normal heart sounds (S1 and S2). Grade II murmurs are equal in intensity to S1 and S2, and grade III murmurs are more intense than S1 and S2. Grade IV murmurs include the presence of a thrill. Grade V murmurs can be heard with only the edge of the stethoscope on the patient’s chest, and grade VI murmurs can be heard with the stethoscope removed from the chest



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wall. Grading diastolic murmurs is subjective and listener dependent. Grade I murmurs are barely audible. Grade II murmurs are faint but audible. Grade III murmurs are easily heard, and grade IV murmurs are loud. The next step is to describe the pitch of the murmur, which is related to the frequency of the sound and reflects the velocity of the turbulent blood flow; higher pitch represents higher velocity of flow. The pitch of the murmur, therefore, provides more information about the potential cause and severity of the lesion. High-frequency murmurs are produced when there are large (or high) pressure gradients between 2 chambers, whereas low-frequency murmurs are produced when there is a smaller (or low) pressure gradient. Knowing where on the chest wall to auscultate each of the 4 valves, as described previously, is important to localize the examination. Where on the chest wall the murmur is heard the loudest should be specified. In addition, where else the murmur can be heard or where it radiates to needs to be determined. Radiation of the murmur follows the course in which the blood flows. For example, murmurs that can be heard in the back and axilla are following the course of the pulmonary blood flow. In general, the sound of innocent murmurs will not radiate, so the presence of this finding should prompt the question of a need for further evaluation. Certain types of murmurs can be altered by positional changes, respiration, or maneuvers. This can help to differentiate similar murmurs from each other. In general, innocent murmurs will vary in intensity, depending on the patient’s position during auscultation. Innocent murmurs are usually loudest when lying supine and diminish in intensity or disappear when sitting upright or standing. One exception to this is a venous hum, which resolves or diminishes when lying supine. A lack of change in murmur intensity with position change should raise suspicion for a pathologic murmur. Squatting is another positional change that can be helpful when evaluating a murmur. In patients with hypertrophic cardiomyopathy, the murmur intensity decreases with squatting and increases with standing.

The Stethoscope The bell of the stethoscope is best suited to hear low-frequency events, while the diaphragm of the stethoscope selectively picks up higher-frequency sounds. Using only the diaphragm of the stethoscope may result in missing some low-pitched sounds, such as a diastolic rumble, pulmonary regurgitation, or Still murmur (also commonly referred to as Still’s murmur). Innocent or functional murmurs are common in children. They occur in the absence of anatomic anomalies. Examples include vibratory murmurs, pulmonary flow murmurs, venous hums, and carotid bruits.

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Key Points •• History and physical examination remain important tools in the evaluation of children with murmurs and other common cardiac complaints. •• A thorough history should contain a detailed personal history of the child, maternal history during pregnancy, the child’s birth history, past medical history, review of systems, family history, and social history. •• In adolescent patients, it is important to obtain the history directly from them and assess the role psychosocial stress may play in their symptoms. •• Heart rate, respiratory rate, oxygen saturation, and blood pressure should be assessed at each visit. •• In addition to physical palpation of the pulse in the upper and lower extremities, blood pressure measurements should be obtained in the upper and lower extremities during the first visit to assess the patient for coarctation of the aorta.

Audio Recordings ()

•• Normal Third Heart Sound (S3) (Willam Buck Kyle, MD). www.youtube.com/watch?v=DxMnm5C5PW8&index=1&list= PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu •• Bicuspid Aortic Valve and Systolic Click—normal speed (Willam Buck Kyle, MD). www.youtube.com/watch?v=zsAj2xGNGs4&index=3&list= PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu •• Bicuspid Aortic Valve and Mild Stenosis—normal speed (Willam Buck Kyle, MD). www.youtube.com/watch?v=opyMtEHhyLE&index=4&list= PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu •• Bicuspid Aortic Valve and Mild Stenosis—slow (Willam Buck Kyle, MD). www.youtube.com/watch?v=dsoG-OX_Wv8&index=5&list= PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu •• Small Muscular Ventricular Septal Defect—normal speed (Willam Buck Kyle, MD). www.youtube.com/watch?v=VLD0ao6lQ3M&index=8&list= PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu •• Small Muscular Ventricular Septal Defect—slow (Willam Buck Kyle, MD). www.youtube.com/watch?v=BJ-1c4JFY9Y&index=9&list= PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu •• Restrictive Membranous Ventricular Septal Defect—normal speed (Willam Buck Kyle, MD). www.youtube.com/watch?v=dnzZDGKMW5I&index= 10&list=PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu •• Restrictive Membranous Ventricular Septal Defect—slow (Willam Buck Kyle, MD). www.youtube.com/watch?v=bpEKVgXQPhY&index=11&list= PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu 11

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•• Restrictive Muscular Ventricular Septal Defect (Willam Buck Kyle, MD). www.youtube.com/watch?v=jXvE1otbxac&index=12&list= PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu •• Restrictive High Muscular Ventricular Septal Defect (Willam Buck Kyle, MD). www.youtube.com/watch?v=l-pLcHQVjQA&index=13&list= PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu •• Restrictive Mid Muscular Ventricular Septal Defect—slow (Willam Buck Kyle, MD). www.youtube.com/watch?v=7YeB7wbVFNc&index=14&list= PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu •• Restrictive Apical Muscular Ventricular Septal Defect—slow (Willam Buck Kyle, MD). www.youtube.com/watch?v=nKlCgY_XtjM&index= 15&list=PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu •• Pulmonary Stenosis—mild (Willam Buck Kyle, MD). www.youtube.com/ watch?v=8uk8iKxu5HY&index=17&list=PLKCIeugVenPTLW-nspw_ wUkXxO2IIiesu •• Aortic Regurgitation and Mild Stenosis (Willam Buck Kyle, MD). www.youtube.com/watch?v=54BhXSnaXk4&index=19&list= PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu

Reference 1) Keren R, Tereschuk M, Luan X. Evaluation of a novel method for grading heart murmur intensity. Arch Pediatr Adolesc Med. 2005;159(4):329–334

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CHAPTER 2

Electrocardiography Daniel Mauriello, MD

Introduction Electrocardiography (ECG) provides information regarding the conduction of electricity throughout the heart. Standard ECG in children has either 12 or 15 leads (see Figure 2-1). Each lead provides information from a particular vantage point on the chest, like an “electrical camera.” ECG tends to be useful for determining rhythm but can also provide insights into structural or systemic disease and cardiomyopathies. The limb leads (I, II, III, aVR, aVF, aVL) provide information about how electricity moves in the superior-inferior and left-right directions. These leads are useful for helping to determine rhythm, atrial enlargement, and overall direction of net electrical force (axis). The precordial leads provide information about the movement of electrical activity in an anterior-posterior and left-right direction (Figure 2-1). This can be helpful for determining ventricular hypertrophy. Both precordial and limb leads can provide information about conduction delays and blocks, ischemia, myocardial disease, and structural abnormalities of the heart. Standard ECG (Figure 2-2) captures 10 seconds of data. While the limb and precordial leads can be configured to display in numerous ways, typically, the left portion of the ECG tracing contains the limb leads, and the right portion contains the precordial leads. Usually, 1 or more rhythm strips (RSs) of a continuous lead tracing are recorded at the bottom, with lead II often being used because most ventricular forces are frequently directed toward this lead. The upper portion of the ECG tracing contains demographic data, computer-calculated intervals, and a computer-determined analysis of the ECG tracing. The tracing is made on a background of 1-mm × 1-mm boxes. On the x-axis, time is typically noted, so each small box is 40 ms, and each larger box (consisting of 5 smaller boxes) is 200 ms. The paper speed is 25 mm/s (for a 10-second ECG, there will be 250 small boxes representing 40 ms per box); it can be changed but 13

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A Frontal plane leads

aVR -150°

Frontal plane formed by leads I, II, and III and the three unipolar leads

aVL -30°

I 0°

III 120°

II 60°

aVF 90°

B Horizontal plane leads

Horizontal plane formed by chest leads

V6 V1

V2

V V3 V4 5

FIGURE 2-1. Electrocardiographic lead orientation and limb lead vectors. A. The frontal plane leads with the negative electrodes aligned to a central point. The approximate location of the heart is shown for reference. The leads are described relative to lead I. Counterclockwise is defined as the negative direction, and clockwise is the positive direction. B. The horizontal or precordial plane and the relative position of the chest leads. From Kusumoto FM. Cardiovascular Pathophysiology. Raleigh, NC: Hayes Barton Press; 1999. Reprinted with permission from Hayes Barton Press. 14

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Electrocardiography

FIGURE 2-2. Standard 12-lead pediatric electrocardiogram.

typically is not. The paper speed is shown at the bottom of the ECG tracing. The y-axis, also called the amplitude, is simply discussed in boxes or millimeters. At the far left of the strip, the vertical standardization is conveyed by the height of the squared-off column. Standard vertical calibration will include 10 small boxes. Both the limb and precordial leads can have their vertical calibration changed separately. When the ECG is “half standard,” the ECG amplitudes will display at one-half the usual height and, as such, all amplitude measures will need to be multiplied by 2 for making interpretive decisions. Conversely, if displayed as “double standard,” all ECG amplitudes will be twice the usual height and should be halved for interpretation. Change in standardization is often done when the R and/or S waves are overlapping each other, making differentiation difficult. By convention, electrical depolarization forces toward a lead will be displayed as a positive deflection above the baseline, and forces away from the lead will be displayed as a negative deflection. Each lead will show the heartbeat from a different vantage point on the chest. The limb leads can be used to describe the electrical direction in 360° or around a “clockface.” Information about superior-inferior and left-right forces can be determined. Leads I, II, and III are situated 60° apart from each other, between 0° and 120°. For most children and adults, most electrical forces of the heart come from the ventricles. Typically, these forces will be most directed in the range of 0° to 120°. aVF, aVL, and aVR are augmented leads (meaning they are not directly placed on the patient but are virtually determined via vectoral calculation). These leads are at 120° separations 15

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from each other and, in conjunction with leads I, II, and III, can help show a perspective of the heart’s electrical activity from around the entire 360° clockface. The precordial leads are situated on the chest, with V1 (V3R, V4R) starting just to the right side of the sternum, overlying the right ventricle (RV), and progressively moving leftward through V6 (V7), overlying the left ventricle (LV). The quantitative measurements most often used in precordial lead interpretation are the R and S wave heights and ratios that can be used for determination of ventricular hypertrophy.

Interpretation Method While there is no one correct method for ECG interpretation, essential components must be addressed each time for complete and accurate interpretation. The order in which they are addressed is less important than ensuring that each task is addressed each time. Failure to address any of the following components will result in an incomplete assessment of the ECG results. •• Rate •• Rhythm •• Axis •• Atrial enlargement •• Ventricular hypertrophy •• Conduction delays •• Interval assessment •• Segment assessment •• Corrected QT interval (QTc) calculation and assessment •• Repolarization (T wave assessment)

The interpretive method used here will be based on the understanding of the physiology of a normal sinus heartbeat as it occurs through the cardiac cycle. Understanding how the surface ECG correlates with the cardiac cycle allows ECG interpretation to be more deeply linked to underlying cardiac physiological processes.

The Normal Heartbeat Each normal heartbeat (see Figure 2-3) should involve atrial depolarization (from the sinus node), conduction to the atrioventricular (AV) node, depolarization of the ventricles in a nearly synchronous fashion through the His-Purkinje system, atrial repolarization, and, finally, ventricular repolarization. Except for atrial repolarization (which gets lost in the QRS deflections), each of these events is represented on the surface ECG (Table 2-1). Each may appear differently, depending on which electrical vantage point or lead is viewed. Unlike adults, the normative values for many ECG parameters will vary in children, depending on age. Sources may differ slightly in the upper limits of 16

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Sinus node impulse

Impulse passes through AV node

Ventricular impulses

Normal heartbeat

FIGURE 2-3. The normal heartbeat: normal depolarization and conduction. AV = atrioventricular. From Mayo Clinic. Heart Arrhythmia Web site. http://www.mayoclinic.org/diseases-conditions/ heart-arrhythmia/symptoms-causes/dxc-20188128

Table 2-1. Surface ECG Correlation to Cardiac Myocyte Depolarization, Conduction, and Repolarization Physiological Event

ECG Correlate

Atrial depolarization

P wave

Conduction to AV node

PR interval

Ventricular depolarization

QRS complex

Ventricular repolarization

ST segment and T wave

AV, atrioventricular; ECG, electrocardiography.

normal (ULNs) and mean values. A reference range of normal pediatric values is a required companion for ECG interpretation. In this chapter, the data of Davignon and colleagues are provided (Table 2-2) and have been widely used for years, but additional sets of normative data are also available.1,2

The P Wave The normal heartbeat begins with depolarization of the sinus node, which is a right-sided posterolateral structure situated near the junction of the superior vena cava and the right atrium. As the right atrium depolarizes, the forces are 17

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1–3 mo

8–30 d

4–7 d

73–138

(101)

65–159

(110)

106–

182

(98)

(75)

179

(149)

73–130

31–115

120–

(148)

(104)

(+133)

75–137

76–168

(108)

81–139

(128)

(+134)

(124)

(107)

79–160

PR Interval (ms)

90–166

65–171

91–158

(+135)

(122)

3 boxes tall b. LAE P waves >2–2.5 boxes wide or terminal P wave >1 box 4. PR interval = ___ ms (Normal/Abnormal) 5. Is there PR depression or elevation? (Yes/No) a. >1 box from baseline (TP segment) 6. QRS duration = ___ ms (Normal/Abnormal) a. Narrow QRS indicates likely normal ventricular depolarization through the His-Purkinje system 7. Are there abnormal Q waves? (Yes/No) a. Q waves >½ box wide or deeper than ULN in III or V6 8. QRS axis = ___ degrees (Normal/LAD/RAD) 9. Ventricular rate = ___ beats/min (Normal/Abnormal; if sinus rhythm, atrial = ventricular rate) 10. Are the QRS complexes related to the P waves 1:1? (Yes/No; if not, what’s the relationship?) 11. Is there normal R wave progression through the precordial leads? (Yes/No) 12. RVH/LVH based on voltage in V1/V6 or mid-precordial leads? (Yes/No) 13. ST segment elevation/depression? (Yes/No) 14. T waves normal in morphologic appearance and axis? (Yes/No) 15. QTc = ___ ms (Normal/Abnormal) LAD, left axis deviation; LAE, left atrial enlargement; LVH, left ventricular hypertrophy; RAD, right axis deviation; RAE, right atrial enlargement; RVH, right ventricular hypertrophy; ULN, upper limit of normal.

Atrial Rhythm and Conduction Abnormalities As discussed previously, there are 4 essential criteria for sinus rhythm. When these criteria are not met, the rhythm must be further analyzed. Abnormalities in the atrial rhythm can come as a result of the atrial rate being tachycardic or bradycardic or coming from an abnormal place of activation. As a quick guide, the maximum sinus rate can be estimated by subtracting the patient’s age from 220 beats per minute. Premature neonates who present with anemia, pain, and dehydration can have sinus heart rates into the 230s, but rates higher than 220 in most children should raise suspicion for an abnormal mechanism of tachycardia. Understanding normal physiological responses is crucial if we are to begin understanding abnormal mechanisms. 26

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Sinus Tachycardia

Sinus tachycardia is a response of the sinus node to extracardiac stimulation. Sinus tachycardia, like sinus bradycardia, is rarely a manifestation of primary cardiac disease. Pain, dehydration, anemia, conditions associated with excess release of catecholamines, and hyperthyroidism are common causes of sinus tachycardia. It is important to recognize that the heart rate may increase quickly, over several beats in sinus tachycardia, particularly when driven by sudden stimulation, such as being poked by a needle, but as opposed to supraventricular tachycardia (SVT), the change in heart rate does not occur in a single heartbeat. Similarly, when sinus tachycardia resolves, it typically returns to baseline more gradually. Extreme sinus tachycardia, particularly in neonates, can at times be challenging to differentiate from abnormal mechanisms of narrow complex tachycardia. The use of telemetry can be helpful in seeing the onset and resolution of the tachycardia. Particular attention should be paid to changes not only in the onset of rate, but also in P wave axis or morphologic appearance. Sinus tachycardia should have the same appearance of P waves as the slower sinus rate but simply at a faster rate with shorter intervals.

Supraventricular Tachycardia

Speaking grammatically, SVT would include any cause of tachycardia that originates above the ventricles, but from a clinical perspective, SVT generally refers to re-entrant tachycardia, of which there are 2 broad varieties, AV re-entrant tachycardia (AVRT) and AV node re-entrant tachycardia. AVRT, the most common type of SVT in neonates and small children, requires involvement of 4 components: the atria, AV node, ventricles, and accessory pathway (see Figure 2-5).5 In this situation, there is normal sinus depolarization with activation of the AV node and ventricles, and the accessory pathway will conduct an impulse up to the atria, but under most circumstances, the atria are still repolarizing and are refractory to stimulation. Any number of events (premature atrial contractions, premature ventricular contractions [PVCs], or change in vagal tone) can change the timing cycles of the atria, AV node, ventricles, or accessory pathway so that when the accessory pathway stimulates the atria, the atria are repolarized. If the timing of the 4 parts of the pathway are altered so that each can be continually depolarized in circular succession from atria to AV node to ventricle to accessory pathway, the re-entrant circuit can propagate until broken. SVT is essentially an all-or-none phenomenon with patients either being in SVT or not (Figure 2-6). Once in SVT, the atria are no longer activated by the sinus node but are rather activated by the accessory pathway. Given the abnormal mechanism of atrial activation in SVT, if P waves are seen, they often have an abnormal axis or morphologic appearance. P waves are often not seen in SVT because they are buried in QRS complexes or the T waves. Slower SVT may show the abnormal P waves. Understanding this physiology can help differentiate SVT from 27

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Electrocardiogram

P

AVN

P

P

P

AP

Sinus rhythm

Orthodromic atrioventricular reentrant tachycardia

Antidromic atrioventricular reentrant tachycardia

FIGURE 2-5. Mechanism of atrioventricular reentrant tachycardia. AP = accessory pathway, AVN = atrioventricular node. From reference 5.

FIGURE 2-6. Supraventricular tachycardia (SVT, box) and premature atrial contractions (PACs) (arrows) in a 3-week-old premature neonate. A 7-beat run of SVT is started by a PAC. About three-quarters of the way through the electrocardiogram, another PAC is seen as the early P wave is in the preceding T wave. SVT stops and starts suddenly in a single beat. The heart rate is over 270 beats/min, and the QRS is narrow. 28

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other narrow-complex tachycardias. Please see Chapter 10, Palpitations and Arrhythmia, for the role of adenosine in both treatment and diagnosis. Table 2-3 provides comparisons between sinus tachycardia, SVT, and atrial tachycardia.

Ectopic Atrial Tachycardia

Cardiac myocytes have the property of automaticity with clusters of cells in the sinus node; the AV node has the second fastest rates of depolarization. Ectopic atrial tachycardia (EAT), often called simply atrial tachycardia, occurs when a cluster of cells in the atria outside of the sinus node begins depolarizing at a frequency greater than the sinus node. Unlike the sinus node, which exists as a right-sided posterior structure typically near the junction of the SVC and the right atrium, the focus of depolarization for EAT can come from anywhere in either atrium. Like sinus tachycardia, EAT often occurs with a warm-up or cool-down period, which may appear quick (over several heartbeats) but will not change from baseline to a consistent higher rate in a single heartbeat as re-entrant SVT does. When examining the ECG, one of the keys to identifying EAT is to observe that the P wave morphologic appearance or axis will change when compared to the P wave in sinus rhythm (Figures 2-7 and 2-8). For a left atrial rhythm, the P wave axis will be negative in lead I, as the wave of depolarization is now moving left to right, away from lead I. If the focus of cells is in the low portion of the atrium, the P wave will be negative in aVF because the atria are now depolarizing from the bottom to the top, and forces are moving away from aVF. If the focus of EAT is in the low right atrium, lead I will still appear with a positive P wave, but aVF will be negative. In addition to the location of the tachycardia focus, types of EAT can vary in terms of how quickly the rate increases or decreases, the peak heart rate, and the response to catecholamines.

Table 2-3. Comparison Between Sinus Tachycardia, SVT, and Atrial Tachycardia Sinus Tachycardia

SVT

Atrial Tachycardia

Heart rate (beats/ min)

220

Variable

P waves

Normal

Absent or abnormal axis

Often abnormal

Start and stop

Gradually

Single beat

Gradually

Effect of adenosine

P waves continue; QRS complexes are blocked

Tachycardia breaks

Flutter waves continue; QRS complexes are blocked

SVT, supraventricular tachycardia.

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FIGURE 2-7. Ectopic atrial tachycardia in an 18-year-old cross-country runner with racing heartbeats at rest. This is a relatively slow example, which shows the abnormal P wave axis. The P wave is originating from low in the atrium (negative in aVF, II, and III; most positive in aVR). The heart rate is 102 beats/min.

FIGURE 2-8. Ectopic atrial tachycardia in a 1-week-old neonate with tachycardia. Note that the P waves are negative in leads I and aVF and positive in aVR, indicating that the focus of the ectopic tachycardia is in the low left atrium.

Atrial Flutter

Like SVT, atrial flutter involves a circuit, except that instead of involving the atria, AV node, ventricles, and accessory pathway, the atrial flutter circuit is solely contained in the atria. This results in rapid, frequent depolarization of the atria, with rates that can exceed 300 times per minute. These frequent atrial depolarizations are conducted to the AV node and then to the ventricles. The appearance of these abnormal flutter waves on the ECG tracing is often described as “sawtooth.” Depending on the atrial rate, conduction to the ventricles may be 30

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1:1, but at higher rates, the AV node and His-Purkinje fibers may not have time to repolarize and may therefore not conduct (referred to as blocking). If there are 2 atrial depolarizations (2 flutter P waves) for each QRS seen, this is described as atrial flutter with 2:1 block (if there are 3 P waves for each QRS, then it is 3:1 block, and so on) (Figure 2-9). At times, the relationship between the flutter P waves and the ventricular QRS complexes is not consistent; this is termed variable conduction (Figure 2-10).

WPW and Pre-excitation

WPW is a particular type of abnormal conduction in the heart that may lead to an abnormal heart rhythm, SVT. As discussed previously, for SVT known as AVRT to occur, the 3 normal parts of the conduction pathway (atria, AV node, and ventricles) interact with the abnormal accessory pathway to create the obligate circuit. In the prior example, the normal conduction occurred down the usual conduction system (orthodromic), and the accessory pathway conducted an impulse from the ventricles to the atria. In situations in which the accessory pathway can conduct in the direction from the atria to the ventricle, the AV node is bypassed briefly during sinus rhythm. The normal delay of

FIGURE 2-9. Atrial flutter with 3:1 conduction: Looking only at V1, the diagnosis of atrial flutter can be challenging, emphasizing the importance of using all the leads for electrocardiography.

FIGURE 2-10. Atrial flutter with variable conduction in a 17-year-old. The relationship of P (flutter) waves and QRS complexes varies between 2:1 and 3:1. 31

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conduction through the AV node, which gives rise to the usual PR interval, is bypassed, resulting in what is termed pre-excitation as the ventricles are initially depolarized from the accessory pathway. Shortly after ventricular depolarization begins from the accessory pathway, the normal AV node delay has occurred, and the action potential is propagated down the normal pathway of the His-Purkinje system. This results in the ECG showing a short PR interval with a slightly wide QRS complex at the base because of the slurring of the upstroke from the pre-excitation. The initial abnormal portion of the QRS resulting from the accessory pathway depolarizing the ventricle is termed the delta wave. The combination of the delta wave and the short PR interval is termed WPW pattern (Figure 2-11). Because patients with WPW have an accessory pathway and, as a result, have the 4 obligate parts of a re-entrant circuit, they are at risk for SVT. Once an individual with WPW pattern begins experiencing SVT, the diagnosis of WPW syndrome is established. While SVT is the most common arrhythmia seen in those with WPW, the increase of sudden death in people with WPW syndrome is thought to be largely from patients having atrial fibrillation or flutter, which, depending on the accessory pathway, may be conducted in a 1:1 manner to the ventricles. If this occurs, atrial fibrillation or flutter is effectively converted into the ventricular equivalent.6

FIGURE 2-11. Wolff-Parkinson-White (WPW) pattern in a 14-year-old with palpitations. The PR interval is very short. The QRS complex begins almost as soon as the P wave ends, leaving virtually no PR segment. The base of the QRS complex appears wide because of the delta wave (arrow). The delta wave is created because the accessory pathway from the atria to the ventricle pre-excites the ventricles, briefly bypassing the atrioventricular node. The PR interval appears shorter in V6 than in lead I; this reflects the location of the accessory pathway and emphasizes the need to examine all leads for the features of WPW pattern.

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Sinus Bradycardia and Escape Rhythms

Sinus bradycardia occurs when the heart rate falls below the normal range for age. This can come from many sources, but rarely is sinus bradycardia a result of abnormal sinus node function. As with sinus tachycardia, sinus bradycardia almost always comes from extracardiac sources. These may include increased vagal tone, low thyroid hormone, athletic conditioning, sepsis, increased intracranial pressure, acidosis, and hypothermia. Sinus bradycardia is addressed by treating the underlying condition. As previously mentioned, all cells in the heart have automaticity. If the degree of sinus node depolarization is less than the rate of automatic depolarization of other cells (typically 40–60 beats/min for the AV node and 15 mm in infants younger than 1 year), it can be a sign of RVH. LEFT BUNDLE BRANCH BLOCK

If the left bundle is damaged, activation of the RV will occur normally through the functional right bundle branch, while the LV will activate in a delayed fashion through a wave of depolarization coming from the RV instead of the left bundle. This will show on the ECG tracing as a wide R wave in V6, with the S wave, if present, appearing relatively narrow. In V1, if the R wave from RV depolarization is present, it will appear narrow. V1 may only show a wide S wave, representing the delayed LV depolarization in LBBB (Figure 2-22). Because the ventricles are being activated abnormally with both RBBBs and LBBBs, the QRS axis is typically deviated. RBBBs are commonly seen after congenital heart surgery in children, particularly after ventricular septal defect closure. Ventricular septal defect patches are sewn on the RV side of the septum and may often interrupt the right bundle with suture placement. LBBB can also be seen after heart surgery. Either LBBB or RBBB can be seen with cardio­myopathy, myocarditis, drug overdose, or ischemia, and, rarely, as a congenital finding.9,10

FIGURE 2-21. Right bundle branch block in a 13-year-old who underwent repair of tetralogy of Fallot as an infant; rsR′ is noted in V1, with increased duration of the R′. The S wave (while small) appears narrow, indicating normal depolarization of the left ventricle. On V6, the R wave has a normal duration and appearance while the S wave is prolonged, indicting the abnormal depolarization of the right ventricle. 41

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FIGURE 2-22. Left bundle branch block (LBBB) in a 17-year-old. Note the wide S wave in V1 and the wide R wave in V6. Often with LBBB, the right ventricular force may not be seen because of the dominance of left ventricular forces.

ST and T Wave Abnormalities

The ST segments represent the transition from ventricular depolarization to repolarization. Many children and adolescents will show J point elevation or early repolarization (Figure 2-23). It is important to differentiate this from pathologic ST elevation. With early repolarization, the entire ST and T wave complex appears slightly elevated from baseline, but the appearance of the ST segment and T wave are otherwise normal. In adults, early repolarization can be associated with increased risk of arrhythmia, but risk has not been shown in children, in whom early repolarization is a common finding.11 Pathologic ST elevation may take on a more sloped or abrupt appearance, and the T waves may often appear abnormal. ST elevation can be seen in ischemia, myocarditis, pericarditis, cardiomyopathy, and channelopathies (Figure 2-24). Because the T waves represent ventricular repolarization, it is important to note that this process is much slower than depolarization; therefore, T waves have a longer duration than QRS complexes. As a result, abnormalities in the ventricular myocardium can be seen in T waves before the QRS. It is also important to recognize that if the ventricle depolarizes abnormally, it will repolarize abnormally. In general, changes to the T wave morphologic appearance are not specific for a particular disease and can be seen with hypertrophy, ischemia, inflammation, cardiomyopathy, electrolyte abnormalities (hyperkalemia), and inherited channelopathies (long QT syndrome and Brugada syndrome). Normal-appearing T waves should have a gentle, hill-like appearance. They should be neither flat nor peaked. It is important to note the direction or axis for several leads. T wave changes can be subtle, and it can take time to develop a sense for nonspecific T wave changes.

42

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FIGURE 2-23. Normal sinus rhythm with early repolarization in a 15-year-old with palpitations. In multiple leads, the J point, where the QRS joins the ST segment, is elevated. The ST segments and T waves appear normal.

FIGURE 2-24. Sinus rhythm with ST elevation in the inferior and lateral leads in a 1-month-old with aortic valve stenosis. The abnormal T wave appears diffusely (flattening). Note the abnormal appearance of the ST segment associated with the ST elevation. The T waves are flat in V6 and lead I. There is evidence that the left ventricle is under strain because it is repolarizing abnormally. Note that V2 shows abnormal ST depression.

T waves should always be upright in the left lateral leads V5 and V6 and in 2 of the 3 inferior leads (II, III, and aVF). Flat or inverted T waves in V5 and V6 or in more than 1 of the inferior leads indicate abnormality with LV repolarization (Figure 2-25). In lead V1, at birth, the T wave is upright, and in the first week after birth, the T wave inverts and remains inverted until at least 6 years of age. At some point 43

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FIGURE 2-25. T wave inversion in the left lateral (V5, V6) and inferior (II, III, aVF) leads in a 16-year-old with hypertension and left ventricular (LV) hypertrophy at echocardiography. Inverted T waves in the inferior and left lateral leads indicate an abnormality in LV repolarization. Often, abnormalities in the ventricular myocardium appear in the T waves before the QRS complexes.

after 6 years, the T wave becomes upright, but it can remain inverted through adolescence. An upright T wave in V1 in a child between 1 week and 6 years of age indicates an abnormality in the RV repolarization.

Prolonged QT Interval

Since the QT interval includes the beginning of QRS through the end of the T wave, anything that prolongs either ventricular depolarization or repolariza­ tion will increase the QT interval. This is important to recognize because the main reason for concern with QT prolongation is an increase in the repolari­zation period. With an increase in ventricular repolarization time, the ventri­cular myocardium may be more susceptible to more spontaneous or ectopic depolarization. This can increase the risk associated with ventricular arrhythmia, specifically torsades de pointes. Because intervals at ECG typically decrease as the heart rate increases, the ventricular rate must be accounted for. There are several ways to do this, but the Bazett formula is used most commonly to derive the QTc. QTc = QT/√R-R interval While the math is straightforward, the equation can be problematic when not used regularly because of the differing units used. QTc and QT interval are in milliseconds, while the R-R interval is in seconds on the ECG printouts. At both high and low heart rates, this equation becomes more inaccurate.12 In general, patients with QTc of longer than 500 ms are at increased risk for arrhythmia.4 Normal postpubescent female subjects can have a slightly longer QT interval than others (Table 2-4). Most commonly, lead II or V5 is used for 44

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Electrocardiography

Table 2-4. Normal Corrected QT Intervals Patient Type

Normal Corrected QT Intervals

Postpubertal female

3 minutes) to allow the patient to locate and apply the event recorder. Another advantage of this type of event recorder is that it does not need to be worn continuously and there are no adhesive electrodes to apply and maintain. A loop recorder is another type of monitor that can be useful when symptoms do not occur frequently enough to record activity by other means. An external loop recorder typically involves applying adhesive electrodes to the chest that are 150

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connected to a battery-operated recorder that continuously records the rhythm. However, if no symptoms occur and the rate stays within the programmable parameters, the device will then record over the old rhythm strip and will not save that information. Alternatively, if the patient indicates that a symptom is present or the rate falls outside the set parameters, then the rhythm strip recorded from several seconds prior to the activation, as well as several seconds after the activation, will be stored and can later be transmitted via the telephone to the personnel who will interpret it. This type of device is useful for rare palpitations that occur briefly, which would preclude the use of another handheld device. The disadvantage is that it necessitates that adhesive electrodes be worn and maintained for the duration of the use of the device, which can be difficult in young patients or in situations where adhesion is problematic, such as with heavy perspiration during exercise. Advances in smartphone technology now make it possible to record a heart rate or even a rhythm strip by using a smartphone and even transmit that tracing via the Internet. Some applications require special equipment or attachments. However, caution must be used when selecting a program because not all have been validated clinically for accuracy.3 The previously mentioned event recorders and loop recorders are generally issued in 30-day intervals, but occasionally, symptoms occur less often or are unpredictable, which makes recording the rhythm more difficult. In those cases, an implantable loop recorder may be necessary. An implantable loop recorder is a recording device that is placed under the skin (generally over the left side of the chest) that can record for approximately 2 to 3 years. It functions similarly to external loop recorders in that there are programmable settings to automatically record above and below certain rates, as well as record patient-activated events. The information can be automatically downloaded by using a transmitter that is often placed at the bedside so the events are transmitted to the personnel who will interpret them shortly after recording. Obviously, this is a more invasive approach to monitoring the rhythm, but it can be useful in cases in which external monitoring has not worked or is not possible. If these devices are unable to successfully capture the rhythm during an event or if the suspicion for an arrhythmia is high enough, referral to a pediatric electrophysiologist for more invasive testing may be warranted. Esophageal or intracardiac electrophysiological studies may be needed to fully evaluate the ­conduction system for arrhythmia substrate in certain circumstances. These ­studies also have the added advantage of allowing a potentially curative procedure (an ablation) to be performed at the same time in certain instances.

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Management Sinus Tachycardia Many patients who present with palpitations will undergo an evaluation only to learn that there is no true arrhythmia. It is common to record a rhythm during which there are perceived palpitations, only to find that the rhythm is sinus, with a rate that either is normal or falls into the range of sinus tachycardia for age. When this is noted, the sinus tachycardia is nearly always secondary to another cause, which is most commonly autonomic, orthostatic, or a result of deconditioning. Very rarely is there an underlying primary inappropriate sinus tachycardia, hyperthyroidism, or adrenaline-secreting tumor, such as a pheo­chromocytoma or neuroblastoma. If any of these are suspected on the basis of other clinical findings, then targeted testing may be appropriate.4 Otherwise, increased hydration, liberalization of salt intake, and regular exercise will most often help improve symptoms.

Extrasystoles Premature atrial contractions (PACs) and premature ventricular contractions (PVCs) are referred to as extrasystoles. Most often, these do not cause symptoms and appear as an incidental finding during the physical examination or are noted during monitoring. Extrasystoles do not usually cause symptoms; however, patients may perceive them as single “hard beats” or single “skipped beats.” The definition of a PAC is an atrial beat that occurs before the next expected sinus beat and originates from atrial tissue that is not the sinus node. This results in a P wave morphologic appearance that is different from that of the sinus node. Most commonly, the following QRS complex will look identical to a sinus beat, but if the PAC occurs early enough, the QRS could conduct aberrantly down the His-Purkinje system, resulting in a wide QRS complex, or the PAC may not conduct to the ventricle at all, which is called a blocked PAC (Figure 10-1).

FIGURE 10-1. Electrocardiographic tracings show premature atrial contractions (PACs) that conduct normally (*) or aberrantly (open arrow on the upper tracing) and have blocked conduction to the ventricle (solid arrows on the lower tracing). Note that the PAC is occurring simultaneously with the prior T wave. 152

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The key to distinguishing PACs with aberrancy from PVCs is that a PAC must by definition have a P wave prior to it. However, some P waves are difficult to see because they can occur during the preceding T wave; careful inspection of the T wave is often necessary. PACs in the newborn period are particularly common and tend to resolve without intervention in the days or weeks after birth. Outside of the newborn period, wearing a Holter monitor may be useful to try to correlate symptoms with PACs, quantify the PAC burden, and assess the patient for occult atrial tachycardia, but it is not always necessary, and use should be guided by clinical judgment. The definition of a PVC is an early beat arising from the ventricular muscle that is not preceded by a P wave, which results in a QRS complex that is dif­ferent from a sinus QRS. Generally, PVCs result in a wide QRS because of slower muscle-to-muscle conduction, but on occasion, they may originate from or very near to the His-Purkinje fibers, resulting in a QRS that is fairly narrow (Figure 10-2). Careful inspection of the QRS complex in multiple leads is occasionally required to identify a difference from a sinus QRS. Like PACs, PVCs are most often noted incidentally and are rarely symptomatic. PVCs are common in the pediatric population and occur in up to 40% of pediatric patients.5 Most pediatric patients with isolated PVCs have normal cardiac structure and function. PVCs with more than 1 morphologic appearance, episodes of 3 or more PVCs in a row that constitute ventricular tachycardia (VT), or PVCs that increase in frequency with exercise may imply that there is an underlying cardiac problem such as myocarditis, cardiomyopathy, or a channelopathy. Patients with asymptomatic isolated PVCs that have 1 morphologic appearance, that are suppressed with exercise, and that occur in the presence of a structurally normal heart are almost always benign and rarely require any treatment. Those patients with a high burden of ectopy (generally considered >10% PVCs with a Holter monitor) should undergo serial follow-up by a pediatric cardiologist to watch for the development of PVC-induced ventricular dysfunction, although this generally doesn’t occur until the burden of ectopy is much higher.6 Treatment

FIGURE 10-2. A. ECG tracing shows the typical appearance of premature ventricular contractions (PVCs), with a wide complex QRS and no preceding P wave (*). B. PVCs are shown on the ECG tracing with a relatively narrow QRS complex that differs only slightly from the normal QRS, which likely arises from within or very near the His-Purkinje system (arrows). 153

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for PVCs is reserved for rare cases in which patients are symptomatic from the PVCs or develop ventricular dysfunction due to a high PVC burden. First-line therapy can be antiarrhythmics, but some may elect to perform an ablation procedure initially to avoid medication use and potentially provide a permanent cure. The outcome of PVC ablation in pediatrics is favorable.7,8

Supraventricular Tachycardia Supraventricular tachycardia (SVT) is the most common abnormal mechanism of tachycardia in pediatric patients, with an estimated incidence from 1 in 25,000 to as high as 1 in 250.9 Most often, SVT is a sudden-onset narrow-complex tachycardia in which P waves may or may not be visible between QRS complexes (Figure 10-3). In certain scenarios, SVT will occur as a wide QRS complex tachycardia, but this is less common. The mechanism of SVT in pediatric patients is re-entrant in 90% of cases (either atrioventricular [AV] re-entrant by using an accessory pathway or an AV nodal re-entrant by using 2 inputs into the AV node), but ectopic atrial tachycardia and other less common forms of SVT are possible.10 Because of the re-entrant nature of most of these arrhythmias, they typically have an abrupt onset and abrupt termination, as well as some other commonly associated features (Box 10-2). In addition to the typical clinical features of SVT, patients may also experience diaphoresis, nausea, pale appearance, and lightheadedness, but true syncope is rare. In fact, SVT in an otherwise healthy pediatric patient with a structurally normal heart will be hemodynamically well tolerated for short periods of time (or even longer), even at rates well above 200 beats per minute. While SVT can cause a great deal of anxiety in patients and/or their family members, generally there is adequate time to assess and treat an otherwise healthy child urgently but not emergently. Documenting the tachycardia by recording a rhythm strip or ECG during SVT is crucial prior to the acute treatment of an otherwise stable patient

FIGURE 10-3. ECG tracing shows supraventricular tachycardia at a heart rate of 250 beats/min. 154

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Box 10-2. Common Clinical Features of Supraventricular Tachycardia in Pediatrics Heart rate >220 beats/min or too fast to count Abrupt onset and termination in a single beat Abrupt termination can occur with a Valsalva maneuver Duration of several minutes to hours Occurs without a prodrome

because this will allow for review of the tachycardia by others at a later time. Initial measures to acutely treat SVT include vagal maneuvers, such as ice to the face or performing a Valsalva maneuver, which may abruptly terminate SVT because of transient suppression of AV node conduction. Vagal maneuvers such as gagging and ocular massage should be avoided because they can cause physical harm when not done carefully and properly. Intravenous administration of adenosine can usually abruptly terminate SVT when vagal maneuvers fail. Adenosine should be administered rapidly in a push via a large-bore intravenous catheter that is preferably placed in an upper extremity as near to the heart as possible, followed by an immediate saline flush, because the extremely rapid metabolism of adenosine results in a half-life of 1 to 6 seconds. Failure to properly administer adenosine is the most common reason for failure to terminate SVT. It is important to record the rhythm during adenosine administration because the response may yield information on the exact mechanism of SVT when it terminates; this may have implications in both treatment and prognosis. Before administering adenosine, one must be aware of and prepared to manage the possible side effects, including flushing, brief anxiety or a sense of impending doom, nausea, chest pain, bronchospasm, initiation of atrial fibrillation, transient AV block, and transient hypotension. Once tachycardia has terminated, a baseline ECG should be examined to look for Wolff-Parkinson-White syndrome, which consists of a short PR interval, a delta wave, and a wide QRS complex (Figure 10-4). Routine evaluation for electrolyte disturbances and hyperthyroidism are rarely needed in the absence of signs or predisposing factors because they rarely play a role in the development of SVT. Referral to a pediatric cardiologist and (often) a pediatric electrophysiologist is warranted. The long-term management strategy of SVT is to prevent recurrence; this can be accomplished with either medications or an ablation procedure. First-line medications commonly include β-blockers or calcium channel blockers but do require lifelong compliance to be effective in most cases. Alternatively, once a patient weighs more than 15 kg, it is a class I indication 155

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FIGURE 10-4. Wolff-Parkinson-White syndrome. The delta wave on the ECG tracing is identified by the slurring of the initial QRS complex.

to pursue an ablation as a first-line treatment to obtain a permanent cure and avoid medical therapy because the chances of success are high and the risks are low.11 In patients who weigh less than 15 kg, medical therapy options are usually exhausted before proceeding with an ablation because the risks of the procedure increase below this weight. In general, ablation procedures have a high likelihood of permanently eliminating the abnormal substrate needed for tachycardia, and the risks are low in the modern era.12,13 This makes an ablation procedure an attractive first-line option for many patients who wish to avoid the lifelong cost and inconvenience of taking medications indefinitely.

Ventricular Arrhythmias VT is defined as 3 or more consecutive beats that arise from the ventricular myocardium, occurring at a rate faster than the expected sinus rate for a given patient’s age. However, it is generally accepted that the rate must be at least 15% to 20% above the expected sinus rate or more than 120 beats per minute in a teenager to be considered VT. Runs of ventricular ectopy occurring faster than sinus but below this cutoff rate are referred to as accelerated ventricular rhythm (AVR). It is important to distinguish AVR from VT because AVR generally has an excellent prognosis.14 If no underlying heart disease and/or metabolic or electrolyte abnormalities are present, then AVR is almost always benign. However, AVR does require longitudinal follow-up to assess the patient for resolution and to monitor the patient for the development of ventricular dysfunction, similar to the approach for frequent PVCs. Like the management of PVCs, treatment for AVR is rarely indicated unless it produces symptoms or ventricular dysfunction. 156

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When there is an indication, antiarrhythmics or an ablation procedure can be highly effective.6 True VT is rare in the pediatric population, with an estimated incidence of 1 in 100,000 and even fewer requiring treatment.15 Although pediatric VT is often not life-threatening, particularly in the setting of an otherwise normal heart, all VT requires a thorough cardiovascular evaluation by a pediatric cardiologist because it can be associated with clinically significant underlying cardiac pathologic processes. Establishing that the heart is both structurally and electrically normal is vital before entertaining one of the common causes of benign VT in a child. Testing can be tailored to search for an underlying cause, including CHD, cardiomyopathy, myocarditis, and channelopathies, which would in turn guide the management. However, the initial testing should include echocardiography, ECG, and Holter monitoring, with consideration for an exercise test and cardiac magnetic resonance imaging, depending on the situation. If there is a clinical reason to suspect a possible electrolyte abnormality, then laboratory tests should also be performed, but most pediatric VT will occur with normal electrolyte levels. When approaching VT, it is often useful to group VT on the basis of its char­ ac­teristics to help guide the extent of the workup and management. VT can be described in many ways, but commonly, it is referred to as monomorphic or polymorphic; it can also be classified as VT occurring in the presence of a normal heart versus that occurring in an abnormal heart. Monomorphic VT (all beats have the same QRS morphologic appearance during VT) in the presence of a normal heart is most likely benign, whereas polymorphic VT (changing QRS morphologic appearance during VT) or VT in the presence of heart disease is highly concerning for true pathologic findings and should prompt a more extensive evaluation if no etiologic origin is found with initial testing (Figure 10-5).15

FIGURE 10-5. Polymorphic ventricular tachycardia. Note the beat-to-beat changing of the QRS morphologic appearance on the ECG tracing. 157

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Treatment of VT depends largely on the underlying cause but could include medical therapy with antiarrhythmics and/or an ablation procedure and possibly implantation of a defibrillator in specific situations. However, treatment may not be necessary in the face of a normal heart and slow VT and the absence of symptoms, much like the management of AVR and frequent PVCs, as previously discussed.

Key Points •• Palpitations are common, and recording the rhythm during symptoms is the key to confirming the diagnosis of an arrhythmia. •• The history should guide the level of concern for true arrhythmia and the extent of the workup. •• Extrasystoles are common in pediatrics and most often do not require therapy. •• SVT is often curable with an ablation procedure, which can be considered first-line therapy in children who weigh more than 15 kg.

Resources for Families •• Supraventricular Tachycardia (Mayo Clinic). www.youtube.com/watch?v= bhXpgvrRZsc •• Irregular Heartbeat (Arrhythmia) (American Academy of Pediatrics). healthychildren.org/English/health-issues/conditions/heart/Pages/ Irregular-Heartbeat-Arrhythmia.aspx

References 1) Moore JP, Patel PA, Shannon KM, et al. Predictors of myocardial recovery in pediatric ­tachycardia-induced cardiomyopathy. Heart Rhythm. 2014;11(7):1163–1169 2) Zhang Q, Du J, Wang C, Du Z, Wang L, Tang C. The diagnostic protocol in children and adolescents with syncope: a multi-centre prospective study. Acta Paediatr. 2009;98(5):879–884 3) Wackel P, Beerman L, West L, Arora G. Tachycardia detection using smartphone applications in pediatric patients. J Pediatr. 2014;164(5):1133–1135 4) Sheldon RS, Grubb BP II, Olshansky B, et al. 2015 heart rhythm society expert consensus statement on the diagnosis and treatment of postural tachycardia syndrome, inappropriate sinus tachycardia, and vasovagal syncope. Heart Rhythm. 2015;12(6):e41–e63 5) Massin MM, Bourguignont A, Gérard P. Study of cardiac rate and rhythm patterns in ambulatory and hospitalized children. Cardiology. 2005;103(4):174–179 6) Crosson JE, Callans DJ, Bradley DJ, et al. PACES/HRS expert consensus statement on the evaluation and management of ventricular arrhythmias in the child with a structurally normal heart. Heart Rhythm. 2014;11(9):e55–e78 7) O’Connor BK, Case CL, Sokoloski MC, Blair H, Cooper K, Gillette PC. Radiofrequency catheter ablation of right ventricular outflow tachycardia in children and adolescents. J Am Coll Cardiol. 1996;27(4):869–874

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8) Wackel PL, McCrary AW, Idriss SF, Asirvatham SJ, Cannon BC. Radiofrequency ablation in the sinus of Valsalva for ventricular arrhythmia in pediatric patients. Pediatr Cardiol. 2016;37(8):1534–1538 9) Garson A Jr, Gillette PC. Electrophysiologic studies of supraventricular tachycardia in children. II. Prediction of specific mechanism by noninvasive features. Am Heart J. 1981;102(3 Pt 1): 383–388 10) Ko JK, Deal BJ, Strasburger JF, Benson DW Jr. Supraventricular tachycardia mechanisms and their age distribution in pediatric patients. Am J Cardiol. 1992;69(12):1028–1032 11) Philip Saul J, Kanter RJ, Abrams D, et al; Writing Committee. PACES/HRS expert consensus statement on the use of catheter ablation in children and patients with congenital heart disease: Developed in partnership with the Pediatric and Congenital Electrophysiology Society (PACES) and the Heart Rhythm Society (HRS). Endorsed by the governing bodies of PACES, HRS, the American Academy of Pediatrics (AAP), the American Heart Association (AHA), and the Association for European Pediatric and Congenital Cardiology (AEPC). Heart Rhythm. 2016;13(6):e251–e289 12) Van Hare GF, Javitz H, Carmelli D, et al; Pediatric Electrophysiology Society. Prospective assessment after pediatric cardiac ablation: demographics, medical profiles, and initial outcomes. J Cardiovasc Electrophysiol. 2004;15(7):759–770 13) Van Hare GF, Javitz H, Carmelli D, et al; Participating Members of the Pediatric Electro­ physiology Society. Prospective assessment after pediatric cardiac ablation: recurrence at 1 year after initially successful ablation of supraventricular tachycardia. Heart Rhythm. 2004;1(2):188–196 14) MacLellan-Tobert SG, Porter CJ. Accelerated idioventricular rhythm: a benign arrhythmia in childhood. Pediatrics. 1995;96(1 Pt 1):122–125 15) Roggen A, Pavlovic M, Pfammatter JP. Frequency of spontaneous ventricular tachycardia in a pediatric population. Am J Cardiol. 2008;101(6):852–854

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CHAPTER 11

Heart Murmur Gurumurthy Hiremath, MD, FACC, and Stacie Knutson, MD

Introduction Heart murmurs are heard in up to half of all children.1 Most often they are innocent, resulting from normal blood flow through the normal heart and blood vessels. When confronted with a patient with a heart murmur, the pediatrician must ­determine whether the murmur is innocent or indicative of a cardiac abnormality. In general, a murmur will be innocent if the following criteria are fulfilled: (a) There is no history suggestive of cardiac disease. (b) The patient is asymptomatic. (c) The patient is acyanotic. (d) The murmur is systolic (with the exception of the venous hum) and no louder than grade III. (e) The second heart sound (S2) varies normally with respiration. (f ) The electrocardiography (ECG) and chest radiography findings are normal.

Innocent Heart Murmurs There are 5 innocent heart murmurs of childhood: Still murmur (also commonly referred to as Still’s murmur), pulmonary flow murmur, peripheral pulmonary stenosis, carotid bruit, and venous hum.

Still Murmur Still murmur is the most common innocent murmur heard in children. It is an early systolic, grade I–II/VI, low-frequency murmur with a vibratory or musical quality. It is heard best at the left lower sternal border and apex. This type of murmur will be loudest when the patient is supine and will diminish or disappear with sitting or standing. The cause of a Still murmur is not completely understood but may be due to vibrations of the chordae tendineae during systole and/or increased flow velocity across the aortic valve. It is most commonly heard in children 2 to 161

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10 years of age but can also be heard in infants and adolescents. (Audio available at www.youtube.com/watch?v=dxRx-XZ0WLg&index=2&list= PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu.) ( )



Pulmonary Flow Murmur A pulmonary flow murmur or pulmonary systolic ejection murmur is caused by normal flow across the pulmonary valve. Because of the location of the ­pulmonary valve and the main pulmonary artery as the most anterior cardiac structures, there is little distance between them and the stethoscope, so blood flow in this location can be heard easily in a young and thin individual. Pulmonary flow murmurs can be heard at any age and are usually grade I or II/ VI, non–harsh-sounding, mid-frequency systolic murmurs with a crescendo-­ decrescendo pattern. They are heard best at the left upper sternal border in the pulmonic area with little or no radiation. There should also be respiratory ­variation with the murmur louder with inspiration. It is important to differen­ tiate this from a pulmonic flow murmur caused by an atrial septal defect (audio available at www.youtube.com/watch?v=U_xhNdf2Ggk&index=6&list= PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu and www.youtube.com/watch?v= NFAkj9Fbfmw&index=7&list=PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu) ( ) or valvar ­pulmonary stenosis (audio available at www.youtube.com/ watch?v=8uk8iKxu5HY&index=17&list=PLKCIeugVenPTLW-nspw_ wUkXxO2IIiesu) ( ). If an atrial septal defect is present, the intensity of the murmur will not vary with positional changes, and there will be a widely split and fixed S2. If valvar pulmonary stenosis is present, the murmur has a harsher quality to it and may be associated with a click and radiation throughout the pulmonary distribution (back and axilla).





Peripheral Pulmonary Stenosis Murmur The peripheral pulmonary stenosis murmur is common in neonates. Because of the normal fetal circulation, the main pulmonary artery receives a large volume of blood when compared to the branch and distal pulmonary arteries. As a result, the main pulmonary artery is larger in size relative to the branch and distal pulmonary arteries. This size differential and the sudden increase in blood flow to the lungs (about 20 times that in a fetus) result in turbulent flow and the resultant murmur.2 In addition, the acute angles at which the pulmonary arteries branch further contribute to flow turbulence. Peripheral pulmonary stenosis is a grade I–II/VI, short, systolic ejection murmur heard best at the left upper sternal border, with radiation to the back and axilla. It is a low-frequency murmur that can sound similar to a neonate’s breath sounds. This murmur is heard in the newborn period and should resolve over the first 6 months of life. If it persists beyond 6 months, then further evaluation by a pediatric cardiologist for other etiologic origins should be pursued. 162

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Carotid Bruit Carotid bruits are produced by turbulent blood flow in the brachiocephalic and carotid arteries and can be heard throughout childhood. This type of murmur is an early systolic, grade I–II/VI ejection murmur heard over the origin of these arteries. It is best heard in the supraclavicular region bilaterally but may be louder on the right. The murmur intensity can be diminished with hyperextension of the shoulders. This type of murmur must be differentiated from the murmur of aortic stenosis with or without a bicuspid aortic valve, which can have radiation to the carotid arteries. The presence of an ejection click and a suprasternal notch thrill indicate a bicuspid aortic valve and aortic stenosis. In addition, the murmur of aortic stenosis will not diminish with hyperextension of the shoulders.

Venous Hum A venous hum is a soft, blowing, grade I–II/VI, continuous, high-frequency murmur. The murmur is caused by turbulent venous flow in the superior vena cava. It is best heard in the right clavicular region, which is where venous blood from the right and left arms and head enter the superior vena cava. It can also be heard along the course of the superior vena cava at the right sternal border. The murmur intensity increases when turning the head to the contralateral side or sitting upright and decreases or disappears when lying supine or manually compressing the ipsilateral internal jugular vein. Venous hums are common in children 3 to 8 years of age. The use of positional changes and maneuvers is helpful in differentiating this continuous murmur from a patent ductus arteriosus.

Pathologic Murmurs History A personal and family history helps in identifying risk factors for pathologic murmurs (Table 11-1).3 The presence of a chromosomal abnormality, genetic disorder, or connective tissue disease could suggest structural heart disease. Some examples include ventricular septal defects or atrioventricular canal defects with trisomy 21, tetralogy of Fallot with 22q11 deletion, supravalvular aortic stenosis with Williams syndrome, pulmonary stenosis or hypertrophic cardiomyopathy with Noonan syndrome, bicuspid aortic valve and/or coarctation of the aorta in Turner syndrome, and aortic root dilation with Marfan syndrome and other connective tissue disorders. In a newborn, poor weight gain, increased work of breathing, diaphoresis, and fatigue with poor feeding suggest the presence of cardiac disease. Exertional chest pain or syncope, frequent respiratory infections, or failure to thrive could also be symptoms of unrecognized structural heart disease. Past history of 163

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Table 11-1. Historical Findings Suggestive of Structural Heart Disease in Children with Heart Murmurs Historical Finding

Significance

Family history CHD

More common in children with a first-degree relative who has CHD (three- to 10-fold increased risk); high penetrance with ventricular septal defect and mitral valve prolapse

Sudden cardiac death or hyper­ trophic cardiomyopathy

Increased risk of hypertrophic cardiomyo­ pathy (autosomal dominant pattern)

Sudden infant death syndrome

Can be secondary to undiagnosed CHD lesions

Personal history Conditions that may coexist with CHD, such as aneuploidy (eg, trisomy 21, Turner syndrome), connective tissue disorder (eg, Marfan syndrome), inborn error of metabolism, major congenital defects of other organ systems, syndrome with dysmorphic features

Certain genetic disorders (eg, DiGeorge syndrome, velocardiofacial syndrome) are associated with cardiac malformations Trisomy 21 is associated with an increased risk of atrioventricular septal defects, atrial septal defects, ventricular septal defects, patent ductus arteriosus, and tetralogy of Fallot Turner syndrome is associated with increased risk of coarctation of the aorta, aortic valve stenosis, and left ventricular hypertrophy Marfan syndrome is associated with mitral valve prolapse, aortic root dilation, and aortic insufficiency

Frequent respiratory infections

Respiratory symptoms may be attributable to heart disease (ie, congestive heart failure); enlarged vessels may lead to atelectasis or difficulty clearing respiratory secretions, thereby promoting infection

Kawasaki disease

Leading cause of acquired cardiac disease in children; can cause coronary artery aneurysm and stenosis

Rheumatic fever

Associated with development of rheumatic heart disease

Prenatal or perinatal history In utero exposure to alcohol or other toxins

Fetal alcohol syndrome is associated with an increased risk of atrial and ventricular septal defects and tetralogy of Fallot

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Table 11-1. Historical Findings Suggestive of Structural Heart Disease in Children with Heart Murmurs, continued Historical Finding

Significance

Prenatal or perinatal history, continued In utero exposure to selective ­serotonin reuptake inhibitors or other potentially teratogenic medications

Selective serotonin reuptake inhibitor exposure is associated with a small but statistically significant increased risk of mild heart lesions, including ventricular septal defects and bicuspid aortic valve (although not all studies showed an increased risk) Lithium exposure is associated with Ebstein anomaly of the tricuspid valve Valproate (depacon) exposure is associated with coarctation of the aorta and hypoplastic left heart syndrome

Intrauterine infection

Maternal infections may increase risk of structural heart lesions (eg, maternal rubella infection is associated with patent ductus arteriosus and peripheral pulmonary stenosis)

Maternal diabetes mellitus

Increased risk of CHD, including transient hypertrophic cardiomyopathy, tetralogy of Fallot, truncus arteriosus, and double-outlet right ventricle

Preterm delivery

CHD is associated with other conditions (eg, genetic disorders, in utero exposure to toxins) that can result in preterm birth; 50% of newborns weighing III/VI Harsh quality Abnormal S2 (Loud, widely split, fixed) Presence of a clicks, opening snaps Presence of S4 Must distinguish patent ductus arteriosus from venous hum (innocent murmur) (audio available at www.youtube. com/watch?v=KBVNJtayzbA&index=16&list=PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu) (). a

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Murmur Neonate

Child/Adolescent

Cyanosis? Respiratory distress? ?Perfusion? No

Yes

Pathologic murmur characteristics? (see Box 11-1)

Possible critical CHD: Urgent cardiology evaluation

No

Yes

Clinical follow-up

Possible CHD: Cardiology referral

Abnormal family/personal history? Abnormal vital signs/saturation? Abnormal pulses?

Yes

Systolic

Audible S1?

No

Yes

Holosystolic: VSD MR TR

Wide/fixed split S2? No

Yes

Diastolic: AR PR MS TS

Continuous

Positional change present? No

Yes

PDA

Venous hum (disappears when supine)

Cardiology referral Reassurance

ASD Pathologic murmur characteristics? (see Box 11-1) AS PS MVP HCM

Innocent murmur

Reassurance

Cardiology referral

FIGURE 11-1. Suggested approach to heart murmurs. AR, aortic regurgitation; AS, aortic stenosis; ASD, atrial septal defect; CHD, congenital heart disease; HCM, hypertrophic cardiomyopathy; MR, mitral regurgitation; MS, mitral stenosis; MVP, mitral valve prolapse; PDA, patent ductus arteriosus; PR, pulmonary regurgitation; PS, pulmonary stenosis; TR, tricuspid regurgitation; TS, tricuspid stenosis; VSD, ventricular septal defect.

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diagnosis of an innocent murmur on the basis of the clinical assessment may provide a more cost-effective approach to the use of TTE.7 Furthermore, if a pathologic murmur is confirmed to be caused by cardiac disease, the patient will require referral to a pediatric cardiologist for management. In this type of situation, it may be beneficial for the patient and his or her family to have the TTE performed, receive the results, and plan for management all in 1 visit to reduce anxiety about the TTE results.

Key Points •• Heart murmurs are common in children. Most heart murmurs are innocent. •• A complete review of the history and a thorough general physical and cardiac examination will help differentiate innocent from pathologic murmurs. •• Once a murmur has been identified as having pathologic features, the next step should be to refer the patient to a pediatric cardiologist.

Audio Recordings ()

•• Still’s (Vibratory) Murmur (Willam Buck Kyle, MD). www.youtube.com/ watch?v=dxRx-XZ0WLg&index=2&list=PLKCIeugVenPTLW-nspw_ wUkXxO2IIiesu •• Atrial Septal Defect (Willam Buck Kyle, MD). www.youtube.com/ watch?v=U_xhNdf2Ggk&index=6&list=PLKCIeugVenPTLW-nspw_ wUkXxO2IIiesu •• Atrial Septal Defect—large secundum (Willam Buck Kyle, MD). www.youtube.com/watch?v=NFAkj9Fbfmw&index=7&list= PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu •• Pulmonary Stenosis—mild (Willam Buck Kyle, MD). www.youtube.com/ watch?v=8uk8iKxu5HY&index=17&list=PLKCIeugVenPTLW-nspw_ wUkXxO2IIiesu •• Continuous Murmur with Restrictive Patent Ductus Arteriosus (Willam Buck Kyle, MD). www.youtube.com/watch?v=KBVNJtayzbA&index= 16&list=PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu

Resources for Families •• Heart Murmur (American Academy of Pediatrics). www.healthychildren.org/ English/health-issues/conditions/heart/Pages/Heart-Murmur.aspx •• Heart Murmurs (American Heart Association). www.heart.org/ HEARTORG/Conditions/More/CardiovascularConditionsofChildhood/ Heart-Murmurs_UCM_314208_Article.jsp •• Heart Murmurs and Your Child (KidsHealth). kidshealth.org/en/parents/ murmurs.html 169

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References 1) McLaren MJ, Lachman AS, Pocock WA, Barlow JB. Innocent murmurs and third heart sounds in Black schoolchildren. Br Heart J. 1980;43(1):67–73 2) Hiremath G, Kamat D. When to call the cardiologist: treatment approaches to neonatal heart murmur. Pediatr Ann. 2013;42(8):329–333 3) Frank JE, Jacobe KM. Evaluation and management of heart murmurs in children. Am Fam Physician. 2011;84(7):793–800 4) Mahle WT, Newburger JW, Matherne GP, et al; American Heart Association Congenital Heart Defects Committee of the Council on Cardiovascular Disease in the Young, Council on Cardiovascular Nursing, and Interdisciplinary Council on Quality of Care and Outcomes Research; American Academy of Pediatrics Section on Cardiology and Cardiac Surgery, and Committee on Fetus and Newborn. Role of pulse oximetry in examining newborns for congenital heart disease: a scientific statement from the American Heart Association and American Academy of Pediatrics. Circulation. 2009;120(5):447–458 5) Campbell RM, Douglas PS, Eidem BW, Lai WW, Lopez L, Sachdeva R. ACC/AAP/AHA/ ASE/HRS/SCAI/SCCT/SCMR/SOPE 2014 appropriate use criteria for initial transthoracic echocardiography in outpatient pediatric cardiology: a report of the American College of Cardiology Appropriate Use Criteria Task Force, American Academy of Pediatrics, American Heart Association, American Society of Echocardiography, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, and Society of Pediatric Echocardiography. J Am Coll Cardiol. 2014;64(19):2039–2060 6) Smythe JF, Teixeira OH, Vlad P, Demers PP, Feldman W. Initial evaluation of heart murmurs: are laboratory tests necessary? Pediatrics. 1990;86(4):497–500 7) Danford DA, Nasir A, Gumbiner C. Cost assessment of the evaluation of heart murmurs in children. Pediatrics. 1993;91(2):365–368

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CHAPTER 12

Evaluation of the Neonate With ­Congenital Heart Disease Caitlin Haxel, MD, and Julie Glickstein, MD, FACC, FAAP

Introduction Congenital heart disease (CHD) is the most common congenital disorder in neonates, with an incidence of 8 to 10 per 1,000 live births.1 Approximately 25% of neonates who receive a diagnosis of CHD have critical heart disease and require cardiac surgery or an interventional procedure during the first year after birth.2 With the advent of fetal echocardiography, many critical congenital heart lesions are now diagnosed during pregnancy.3 However, not all infants with CHD receive diagnoses prenatally. Up to 30% of neonates with critical CHD may appear normal at initial physical examination.4 Delay in diagnosis of these critical lesions can lead to increased morbidity and mortality. It is essential for primary care practitioners to assess any neonate suspected of having heart disease in the neonatal period. Most cardiac consultations in the newborn nursery focus on a referral for a cardiac murmur, cyanosis, abnormal chest radiographic finding, abnormal electrocardio­ graphic (ECG) finding, cardiac arrhythmia, or symptoms of congestive heart failure (CHF). Screening guidelines for critical CHD have been endorsed by the American Academy of Pediatrics, the American Heart Association, and the American College of Cardiology.5 There is evidence that universal screening with 171

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pulse oximetry improves the identification of neonates with critical CHD when compared to physical examination alone (see Chapter 14, Neonatal Screening for Heart Disease).6 The spectrum of presentation of CHD in the neonate is broad and can range from benign to catastrophic. This chapter will focus on the evaluation and identification of both symptomatic and asymptomatic neonates with critical and noncritical CHD.

Evaluation of the Neonate for CHD History The maternal history, antenatal history, and family history should be reviewed to identify possible risk factors that increase the likelihood of CHD. Gesta­ tional age must also be considered. Prematurity, with gestational age less than 37 weeks, increases the risk of CHD by two- to threefold when compared with term neonates.7 Maternal pregestational diabetes, phenylketonuria, systemic lupus erythematous (SLE), Sjogren syndrome, maternal use of certain medications, or maternal infections can increase the incidence of CHD or cardiomyopathy. Specifically, pregestational diabetes mellitus has been associated with an increase in the risk of heterotaxy syndrome, single-ventricle lesions, and dextro-transposition of the great arteries (D-TGA).8 A maternal history of phenylketonuria (if preconception phenylalanine levels are >10 mg/dL [>605.44 mmol/L]) increases the risk for CHD.9 A maternal history of connective tissue disorders, such as SLE or Sjogren syndrome, is associated with cardiomyopathy and congenital heart block. The maternal use of medications such as isotretinoin, lithium carbonate, ethanol, phenytoin, valproic acid, carbamazepine, and angiotensin-converting enzyme inhibitors has been associated with CHD. Finally, maternal (congenital) infections such as rubella, cytomegalovirus, coxsackievirus, parvovirus B19, h ­ erpes simplex, toxoplasmosis (due to Toxoplasma gondii), and human herpesvirus 6 have also been associated with CHD.3 Family history of CHD increases the risk of CHD for the neonate, with differing risks depending on the family member affected and the specific congenital heart defect. Generally, if the mother of a neonate has CHD, this confers a 6% risk of having affected offspring, whereas a father with CHD confers a 2% risk to his offspring. Similarly, having a sibling with CHD confers a 2% risk on a subsequent neonate.10 A family history of syndromes associated with CHD, such as Marfan syndrome, Ehlers-Danlos syndrome, and Noonan syndrome, should also prompt an investigation of the neonate for similar syndromes. It is also important to review the antenatal history, including antenatal imaging. Routine antenatal screening for CHD was previously limited to a 4-chamber view of the heart at approximately 20 weeks’ gestation, which could 172

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be used to detect only approximately 25% of clinically significant CHD cases.11 However, the practice guidelines of the International Society for Ultrasound in Obstetrics and Gynecology now recommend assessment of outflow tracts, which could be used to identify CHD lesions such as tetralogy of Fallot (TOF), double-outlet right ventricle (RV), transposition of the great arteries (TGA), and truncus arteriosus.12 With a higher level of suspicion, fetal echocardiography can then be performed for more definitive diagnosis. It is important to elicit other fetal anatomic abnormalities—such as cleft lip and palate; gastroesophageal, renal, or central nervous system anomalies; or club feet—because of the association with CHD. Finally, it is important to review any antenatal genetic testing to identify chromosomal abnormalities such as 22q11 deletion, 45X, and trisomy 21, 18, and 13.

Clinical Presentation Infants who ultimately require the care of a pediatric cardiologist can have a variety of presentations, including a murmur; cyanosis (often without a murmur); symptoms of heart failure, which include tachypnea, tachycardia, feeding difficulty, or failure to gain weight; or cardiovascular collapse and cardiogenic shock. The latter 2 presentations almost always occur after discharge from the newborn nursery. Auscultating a heart murmur in a routine examination of an infant is not uncommon. Not all CHD lesions are associated with murmurs, and many infants with murmurs do not have structural heart disease. Innocent or benign murmurs are not associated with an anatomic or physiological abnormality. However, many infants with clinically significant CHD have no murmur or a soft systolic murmur at birth, including neonates with large ventricular septal defects (VSDs), single-ventricle lesions, D-TGA, and total anomalous pulmonary venous connection. Therefore, presence or absence of a cardiac murmur is an insensitive marker for CHD. The primary consideration in assessing an asymptomatic neonate with or without a murmur is whether it could be associated with a ductal-dependent lesion, in which case discharging the neonate home without full cardiac evaluation could be life-threatening.

Physical Examination A full physical examination of a neonate with concern for suspected CHD should be performed with the neonate appropriately warmed and quieted. The examination should begin with an assessment of vital signs, including heart rate, respiratory rate, 4-extremity blood pressure, and pre- and postductal pulse oximetry (measured in the right arm and 1 lower extremity). The weight should be obtained and plotted on an appropriate growth curve to determine if the neonate is small, appropriate, or large for gestational age. Concerning vital signs that can alert a physician to possible CHD in the neonate include the following: 173

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1. Abnormal heart rate or irregular rhythm (tachycardia >180 beats/min or bradycardia 60 breaths/min) with or without retractions 3. Abnormal 4-extremity blood pressure (blood pressure >10 mm Hg higher in the right upper extremity than in the lower extremities) 4. Percutaneous pulse oximetry values below 95%, or having an oxygen saturation in the lower extremity than in the right upper extremity, are never normal in otherwise healthy-appearing neonates measured after 24 hours of age.13 See also Figure 14-1 in Chapter 14, Neonatal Screening for Heart Disease, for an algorithm for pulse oximetry screening.

After measuring a full set of vital signs, the clinician should assess the neonate overall, including the presence of dysmorphic features or other congenital abnormalities. The clinician should evaluate the tone and activity of the neonate and assess the neonate for any signs of birth trauma. A full assessment of the respiratory status includes an evaluation of the airway and breathing, noting the respiratory rate, work of breathing, and presence of retractions, nasal flaring, grunting, hypoventilation, or apnea. The cardiac examination includes an inspection of coloring of the mucous membranes and nail beds to assess the neonate for cyanosis. However, cyanosis may not be clinically apparent with mild desaturations (>80% saturation), with anemia, or in darkly pigmented neonates. Systemic perfusion should be assessed by palpating the pulse in the upper and lower extremities. A discrepancy of pulse in the right and left brachial arteries with weak or absent femoral pulse suggests a possible aortic arch abnormality (aortic coarctation, aortic arch hypoplasia, or interrupted aortic arch). A bound­ ing pulse may be present with a moderate to large patent ductus arteriosus (PDA) or a moderate to severe aortic valve insufficiency. Palpating precordial activity allows the clinician to determine whether the heart is located normally, in the left side of the chest. Increased precordial activity can indicate cardiac enlargement. A ventricular impulse that is palpable along the left parasternal area is suggestive of RV volume or pressure overload. A thrill may be present over the right or left upper sternal border or suprasternal notch, which can suggest outflow tract obstruction, such as moderate to severe pulmonary or aortic stenosis. A thrill may also represent a restrictive VSD. Auscultation of the heart can reveal multiple abnormalities, including a benign versus a pathologic murmur, single S2, widely or fixed split S2, clicks, or S3 gallop. Generally, a benign murmur is soft and position dependent (occurring while supine) and occurs during systole, with normal physiological splitting of S2 and with no associated thrill. Pathologic murmurs differ in quality and intensity. Importantly, neonates can have CHD without having a murmur, such as in D-TGA without a VSD. A full discussion of cardiac murmurs is included later in this chapter. 174

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A complete examination also includes auscultation for bruits over the anterior fontanelle or abdomen, indicating cerebral or hepatic arteriovenous malformations. Palpation of the abdomen is important to identify hepatomegaly, which can be associated with heart failure or other causes of increased right-sided heart pressure. Abnormal position of the liver in the midline or left side of the abdomen can also be indicative of heterotaxy syndrome and signal possible CHD.

Differential Diagnosis in Asymptomatic Versus ­Symptomatic Neonates The symptomatic neonate can present with murmur, cyanosis, heart failure, or circulatory collapse. It is crucial to recognize that these different presentations can overlap and reflect the myriad congenital heart lesions that are possible.

Murmur

As discussed previously, murmurs in the neonate can be benign or pathologic. Three murmurs auscultated in the neonatal period are benign when associated with an asymptomatic neonate with normal vital signs and cardiac testing. The murmur of a PDA is generally a soft, higher-pitched, low-intensity systolic murmur heard between 4 and 16 hours of age. Once outside the neonatal period, the murmur of a PDA is typically more continuous, described as a “washing machine–like murmur” (audio available at www.youtube.com/watch?v= KBVNJtayzbA&index=16&list=PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu) ( ). Peripheral pulmonary artery stenosis is a higher-pitched murmur heard throughout the precordium and is heard best in the axillae or in the back. It ­usually resolves in 3 to 6 months with normal growth of the pulmonary vascu­ lature. Finally, a Still murmur (also commonly referred to as Still’s murmur) is described as a lower-pitched, low-intensity systolic murmur heard best at the left lower sternal border and apex (audio available at www.youtube.com/watch?v= dxRx-XZ0WLg&index=2&list=PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu) ( ). It is more common in children, rather than neonates, and usually resolves with age and growth. A murmur can also be a sign of CHD. Pathologic murmurs are generally loud, harsh, pansystolic, diastolic, or loudest on auscultation at the left upper sternal border, right sternal border, or apex. A loud and single S2 can be associated with pulmonary hypertension, aortic atresia, pulmonary atresia, severe pulmonary stenosis, truncus arteriosus, and TOF. A widely or fixed split S2 is associated with atrial septal defects (audio available at www.youtube.com/ watch?v=U_xhNdf2Ggk&index=6&list=PLKCIeugVenPTLW-nspw_ wUkXxO2IIiesu and www.youtube.com/watch?v=NFAkj9Fbfmw&index= 7&list=PLKCIeugVenPTLW-nspw_wUkXxO2IIiesu)( ) and other lesions associated with RV volume overload (total or partial anomalous pulmonary venous connection) or conduction delays. Early systolic clicks can suggest pulmonary or aortic valve stenosis. Mid-systolic clicks can be associated with







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mitral valve prolapse or Ebstein anomaly of the tricuspid valve. An S3 gallop is associated with ventricular dysfunction or left ventricular (LV) volume over­load. Pericardial friction rubs can be auscultated with pericardial effusions or pericarditis.

Cyanosis

Cyanosis can be the presenting sign for neonates with suspected CHD. This bluish skin tone is present when 5 g/dL (50 g/L) of deoxygenated hemoglobin is present in the neonate. However, cyanosis is not clinically apparent in the setting of mild desaturations (saturation >80%) or anemia. Additionally, cyanosis can be difficult to assess in darkly pigmented neonates. Therefore, it is important to obtain a pulse oximetry measurement in both upper and lower extremities. Most commonly, 2 extremities are measured, including the right upper extremity and either of the lower extremities. Cyanotic congenital heart lesions result in cyanosis due to right-to-left shunting of deoxygenated blood into the oxygenated arterial system. The spectrum of cyanotic heart lesions is varied but can be broadly categorized according to whether there is decreased pulmonary blood flow, increased pulmonary blood flow, or severe heart failure due to left-sided heart obstructive lesions. Many cyanotic congenital heart defects are ductal dependent; however, the presence of cyanosis does not imply a ductal-dependent lesion. The 5 more common forms of cyanotic CHD include tricuspid valve anomalies, TOF, TGA, truncus arteriosus, and total anomalous pulmonary venous connection (TAPVC). Cyanotic congenital heart lesions with decreased pulmonary blood flow include tricuspid valve anomalies and variations of pulmonary outflow tract obstructions that range from TOF to critical pulmonary valvar stenosis and pulmonary valve atresia. Tricuspid valve anomalies include tricuspid atresia, tricuspid stenosis, and Ebstein anomaly, which result in varying degrees of obstruction to blood flow across the tricuspid valve and hypoplasia of the RV and RV outflow tract. As a result, deoxygenated blood shunts from the right to the left side of the heart across an atrial communication and mixes in the systemic arterial circulation, causing cyanosis. TOF can result in cyanosis, depending on the degree of RV outflow tract obstruction. Less severe obstruction can lead to a “pink TOF” without cyanosis. More severe ventricular outflow tract obstruction will lead to deoxygenated blood shunting from the RV into the aorta and systemic circulation, resulting in cyanosis. Critical pulmonary valvar stenosis and pulmonary atresia with intact ventricular septum result in severe to complete obstruction of blood flow to the pulmonary arteries. Therefore, both lesions are ductal dependent to provide pulmonary blood flow. In comparison, cyanotic heart lesions with increased pulmonary blood flow include D-TGA, truncus arteriosus, and TAPVC. Neonates with D-TGA have parallel pulmonary and systemic circulations (oxygenated blood is pumped 176

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through the lungs, and deoxygenated blood is pumped through the systemic circulation) and depend on an atrial septal communication, a PDA, and a VSD (if present) for appropriate mixing. For those without adequate atrial communication, as the PDA closes, profound cyanosis and eventually cardiovascular collapse develop. If a large VSD is present, neonates may have less marked cyanosis at birth; however, heart failure may develop as a result of increased pulmonary blood flow. In truncus arteriosus, a single great vessel arises from the heart, from which the aorta, pulmonary arteries, and coronary arteries all arise. This leads to mixing of oxygenated and deoxygenated blood in the systemic arterial circulation, resulting in cyanosis and increased pulmonary blood flow, which can cause heart failure symptoms. In TAPVC, all 4 pulmonary veins fail to connect appropriately to the left atrium and drain into the systemic venous circulation. To maintain cardiac output, there must be atrial communication, ventricular communication, or PDA to allow shunting of deoxygenated blood from the right side of the heart into the systemic arterial circulation, resulting in cyanosis. Critically obstructive left-sided heart lesions, such as hypoplastic left heart syndrome and critical aortic valve stenosis, have inadequate systemic output. In these CHD lesions, cyanosis occurs because of right-to-left shunting of deoxygenated blood via a PDA (from the pulmonary artery into the descending aorta). In these patients, as the ductus begins to close, systemic output is compromised, and cyanosis often quickly progresses to cardiovascular collapse. Differential cyanosis is a difference in measured pulse oximetry of more than 3% between the right hand (preductal) and the foot (postductal). This occurs in the setting of critical coarctation of the aorta and interrupted aortic arch, in which oxygenated blood from the left side of the heart supplies the upper body via vessels proximal to the site of arch obstruction and deoxygenated blood shunts right to left across the PDA to supply the lower half of the body. Differential cyanosis can also occur in neonates with structurally normal hearts with persistent pulmonary hypertension of the newborn and a PDA. Increased pulmonary pressure causes right-to-left shunting across the PDA, providing deoxygenated blood to the lower extremities. Reversed differential cyanosis occurs when the oxygen saturation in the upper extremity is less than that in the lower extremity. This can be seen in neonates with D-TGA with persistent pulmonary hypertension or aortic interruption or coarctation, which causes right-to-left shunting of oxygenated blood via the PDA to the lower extremities, with deoxygenated blood delivered from the left side of the heart to the head and neck vessels. Reversed differential cyanosis can also be noncardiac in etiologic origin. This includes pulmonary disorders, methemoglobinemia, sepsis, hypoglycemia, dehydration, and hypoadrenalism. These can be differentiated from cardiac lesions by means of the history, examination, chest radiography, hyperoxia testing, and echocardiography when indicated. 177

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Acrocyanosis can also occur in neonates and describes the bluish discoloration of the hands, feet, and perioral area, which is attributed to benign vasomotor changes in diffuse venous structures in the periphery of the body.

Heart Failure

Heart failure in infants is a clinical spectrum that ranges from mild symptoms of tachypnea to cardiovascular collapse. Clinical findings of heart failure can include tachypnea, increased work of breathing (grunting, retractions, nasal flaring, and head bobbing), diaphoresis, difficulty feeding, failure to thrive, gallop rhythm, and hepatomegaly. These signs may precede the diagnosis of CHD. Heart failure can develop at varying times throughout the neonatal period, depending on the specific congenital heart lesion and prematurity status. At birth, the pulmonary vascular resistance (PVR) is increased and decreases over the first days to weeks of life. At approximately 6 weeks of life, the PVR should have decreased to normal levels. In premature neonates, the PVR is generally lower at birth when compared to term neonates. This can lead to heart failure symptoms secondary to pulmonary overcirculation at any earlier age. Heart failure symptoms secondary to excessive pulmonary blood flow can develop shortly after birth in neonates with hypoplastic left heart, severe tri­ cuspid regurgitation, or severe pulmonary regurgitation. Within the first week of life, neonates with D-TGA or infracardiac TAPVC or premature neonates with a large PDA will develop heart failure symptoms. At approximately 1 to 4 weeks of age, neonates with critical aortic stenosis, aortic coarctation, or critical pulmonary stenosis will develop heart failure as the PDA closes and either the systemic or the pulmonary blood flow is compromised. The presentation of neonates with left-sided obstructive lesions will depend on the degree of obstruction and the presence of the ductus arteriosus. With a lesser-degree but still clinically significant obstruction, the neonate will often exhibit heart failure symptoms over the first 2 weeks of life. With severe or critical obstruction or with closure of the ductus, the neonate will present with poor perfusion and cardiogenic shock because of a lack of systemic perfusion. Infants with large VSDs, endocardial cushion defects, or large arteriovenous malformations will generally become symptomatic at 4 to 6 weeks of life. Certain congenital heart lesions, such as truncus arteriosus, may manifest with a combination of cyanosis and heart failure due to mixing of oxygenated and deoxygenated blood in the common outflow tract and excessive pulmonary blood flow.

Cardiogenic Shock

Sudden collapse with poor systemic circulation or extreme cyanosis and acidosis suggests a number of differential diagnoses, including sepsis, metabolic derangement, and cardiogenic shock. Cardiomegaly and lack of response to 178

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volume resuscitation suggest a cardiac etiologic origin of shock. In neonates with severe or critically obstructive left-sided heart lesions, inadequate left-sided heart development compromises cardiac output. This can be seen in lesions such as hypoplastic left-sided heart, critical aortic valve stenosis, and critical coarctation of the aorta or interrupted aortic arch. In these left-sided heart lesions, the flow from the RV into the lungs is typically unimpaired. The oxygenated blood returning from the lungs is either completely diverted across an atrial-level communication into the RV (in the case of hypoplastic left-sided heart) or partially diverted to the right side of the heart, depending on the filling properties of the LV. In the right atrium, pulmonary venous blood mixes with desaturated systemic venous blood returning from the body, thereby increasing the oxygen saturation of the right-sided heart blood. The RV maintains the systemic blood flow by ejecting blood through the neonatal PDA. As a result, these neonates depend primarily or entirely on patency of the ductus arteriosus for systemic ­cardiac output. The relatively high saturations of the ductal blood flowing into the aorta minimize the appearance of cyanosis, even though the RV is supplying the entire systemic cardiac output (in hypoplastic left-sided heart or critical aortic stenosis) or the blood flow to the lower body (in coarctation or interrupted aortic arch). The admixture of red and blue venous returns occurs in these “leftsided heart obstructive lesions,” just as in other cyanotic cardiac malformations, but the potential for catastrophic deterioration caused by inadequate systemic flow is much greater as the ductus arteriosus undergoes normal spontaneous closure after birth. Ductal-dependent left-sided heart lesions can appear after discharge from the newborn nursery. Indeed, ductal patency may persist for weeks or, in rare cases, months. The constriction and closure of the ductus arteriosus cause decreased systemic blood flow, oliguria, acidosis, pulmonary edema, and heart failure. As the cardiac output decreases, retrograde blood flow from the ductus into the common coronary artery (ascending aorta) results in decreased right and left coronary artery blood flow, leading to myocardial ischemia, ventricular dysfunction, and death. The clinical presentation of left-sided heart obstructive disease may mimic sepsis; the infant exhibits tachypnea, mottled gray skin, and poor perfusion, with decreased peripheral and central pulses. Critical clues in a 3-week-old neonate that should lead to the consideration of a cardiac diagnosis rather than sepsis include the presence of a gallop rhythm and marked hepatomegaly or cardiomegaly. Profound metabolic acidosis with pH values of 7.0 or less are characteristic. A high serum brain natriuretic peptide concentration may prove to be a cardiac-specific marker of heart failure in this setting.

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Diagnostic Procedures and Imaging Laboratory Evaluation

Initial laboratory evaluation, particularly in a neonate with cyanosis or cardiovascular collapse, should include an arterial or venous blood gas analysis and lactate level to assess the patient for acidosis. To assess the patient for anemia, a hemoglobin or hematocrit level can be obtained from the blood gas analysis (or via a complete blood count). A full electrolyte panel will help rule out electrolyte derangements that can be corrected.

Pulse Oximetry

Pulse oximetry should be used in a calm neonate to obtain simultaneous or direct-sequence oxygen saturation measurements in the right hand (preductal) and either foot (postductal) to assess the patient for cyanosis or differential cyanosis. The left subclavian artery may arise from the aortic arch before or after the ductus arteriosus, so the left hand should not be used for pulse oximetry monitoring. Pulse oximetry screening should be performed later than 24 hours after birth or as late as possible prior to neonatal discharge home. See Chapter 14, Neonatal Screening for Heart Disease, for more details on recommendations for neonatal pulse oximetry screening.

Hyperoxia Test

With the hyperoxia test, relative changes in arterial oxygen tension (Pao2) are used to help differentiate cardiac and noncardiac causes of neonatal cyanosis. For this test, a neonate inspires 21% oxygen (room air); the Pao2 is measured in the right radial artery (preductal) and an artery of a lower extremity (postductal). The neonate is then placed on 100% oxygen for 10 minutes, after which the preductal and postductal Pao2 measurements are repeated. In the absence of a fixed cardiac shunt, the administration of 100% oxygen to a neonate will increase alveolar partial pressure of oxygen and therefore increase the pulmonary venous and systemic arterial oxygen saturation. In the presence of cyanotic congenital heart lesions, such as D-TGA, administration of 100% oxygen will cause little or no increase in the systemic arterial oxygen saturation.14 An exception occurs in neonates with clinically significant pulmonary hypertension and an intracardiac (patent foramen ovale) or extracardiac (PDA) shunt, which can allow for right-to-left shunting. Additionally, common mixing conditions with high pulmonary blood flow, such as truncus arteriosus or single ventricle with PDA, may have an increase in Pao2 after 100% fraction of inspired oxygen. In comparison, respiratory conditions with severe ventilation-perfusion mismatch may not have an increase in Pao2 after inspiration of 100% oxygen.

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Electrocardiography

ECG should be performed in all neonates with concern for CHD. An abnormal ECG finding in a neonate can manifest as an abnormal QRS axis, abnormal P wave axis, atrial enlargement, ventricular hypertrophy, conduction delay, or abnormal T wave inversion. In an asymptomatic newborn, an abnormal ECG finding can be the first indicator of possible CHD. However, asymptomatic or symptomatic newborns with clinically significant CHD can have an ECG finding that is normal for their age. For example, neonates with D-TGA, TOF, or truncus arteriosus often have ECG findings normal for their age, despite having clinically significant CHD. The T wave in V1 should be inverted by day 5 after birth. Upright T waves after day 5 suggest RV hypertrophy. Neonates with tricuspid atresia will classically have ECG findings that demonstrate left-axis deviation, right atrial enlargement, and LV hypertrophy. Newborns with pulmonary atresia will usually have a cardiac axis between 0 and 90 degrees, which is abnormal in a neonate. Newborns with hypoplastic left heart syndrome will have an ECG finding of normal QRS axis for age with a paucity of LV forces.

Chest Radiography

Chest radiography is an extremely useful modality for the assessment of cardiac size, cardiac position in the thoracic cavity, pulmonary vascular markings, and abdominal situs. Chest radiography is an important tool for the differentiation of cardiac and pulmonary disorders. Specifically, the size and shape of the cardiac silhouette may yield diagnostic clues; for example, the “boot-shaped heart” in TOF,15 the “egg on a string” in TGA, and the massive cardiomegaly associated with Ebstein malformation of the tricuspid valve are classic patterns that suggest specific cardiac lesions. Increased or decreased pulmonary vascular markings may suggest excessive or restricted pulmonary blood flow. Aortic arch sidedness can also suggest the presence of CHD. While a right-sided aortic arch may be an isolated finding in an otherwise structurally normal heart, it can also be associated with conotruncal malformations such as TOF, double-outlet RV, and truncus arteriosus. Examination of the pulmonary fields may demonstrate airway disease, pneumothorax, pleural effusion, pulmonary hypoplasia, elevation of the hemidiaphragm, or diaphragmatic hernia.

Echocardiography

Echocardiography can assist in establishing a definitive anatomic diagnosis and can be used to assess cardiac function when any critical or noncritical cardiac lesion is suspected. All newborns and infants with signs or symptoms concerning for critical CHD (shock unresponsive to volume resuscitation, cyanosis), an abnormal ECG finding, an abnormal chest radiographic finding, a positive pulse oximetry screening result, or a genetic disorder or extracardiac malformation associated with a cardiovascular malformation should undergo complete 181

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(2-dimensional imaging, with pulsed and color Doppler imaging) high-quality echocardiography performed by a skilled technician, with results interpreted by a clinician with expertise in the diagnosis of CHD, such as a pediatric cardiologist.

Management Most cardiac consultations in the newborn nursery focus on a referral for a cardiac murmur, cyanosis, abnormal chest radiographic or ECG findings, cardiac arrhythmias, and possible CHF. The care of the neonate with suspected CHD varies with the presentation of the neonate. An asymptomatic neonate with a persistent murmur who is feeding well and has an otherwise benign evaluation finding, including normal physical examination findings, 4-extremity blood pressure, and pulse oximetry screening, should undergo follow-up with a cardiology referral and testing as indicated (ECG and/or echocardiography) but may not require emergent evaluation. If, however, there is a symptomatic neonate with cyanosis, signs of heart failure, abnormal 4-extremity blood pressure, positive pulse oximetry screening, or abnormal ECG or chest radiographic finding, then urgent cardiac evaluation is indicated, including a complete echocardiographic examination. This neonate should not be discharged from the hospital without excluding potentially life-threatening conditions. If a neonate presents with worsening cyanosis, severe heart failure, or shock, initial management should begin with an assessment of airway, breathing, and circulation, including early intubation and ventilation if needed. Physicians should correct acidosis, hypoglycemia, hypocalcemia, and other electrolyte abnormalities. Sepsis and metabolic disease should be considered and appro­ priately treated. For any neonate with a concern for a congenital heart defect that is ductal dependent for pulmonary or systemic blood flow, prostaglandin should be considered and initiated at any time. The primary physician does not need to wait for a cardiologist consult or an echocardiographic examination to confirm a diagnosis if there is a concern for a prostaglandin-dependent critical congenital cardiac lesion. Prostaglandin should be considered for neonates with profound or increasing cyanosis or neonates with acidosis and shock. Possible side effects of prostaglandin include apnea, jitteriness, convulsions, low-grade pyrexia, flushing, and diarrhea, which should improve with reduction in dose.

Ongoing Care After a diagnosis of heart disease is established in a neonate, the follow-up medical care, including a discussion about potential complications and prognosis, depends greatly on the underlying diagnosis. The need for intervention can include medications, cardiac catheterization, and/or cardiac surgery, either in the neonatal period or later in life. It is important to realize that even if the diagnosis 182

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of CHD was established prenatally, it can be overwhelming for families to deal with the knowledge that their child has heart disease. Families depend on the knowledge and support of their child’s cardiologist, as well as the medical care and support they receive from their child’s primary care physician.

Conclusion The presentation of CHD in the neonatal period is varied and depends on the lesion. The spectrum of disease ranges from mild to a life-threating ductal-dependent lesion. It is through a careful history and physical examination, along with pulse oximetry, ECG, and chest radiography, that a congenital heart lesion can be suspected. Every neonate should have pulse oximetry performed before discharge from the newborn nursery. This is especially important because cyanosis in the newborn nursery can be missed. Diminished or bounding pulses can be a presentation of CHD. Dysmorphic features or the presence of other anatomic abnormalities can be a marker for CHD. All neonates with a heart murmur, in whom a definitive diagnosis has not yet been established when they leave the nursery, should be referred to a pediatric cardiologist for evaluation. Echocardiography can be used to establish a definitive anatomic diagnosis. Always consider CHD in a “sick neonate.” Identifying congenital heart lesions, especially critical ones, requires a high index of suspicion by the primary care physician.

Key Points •• The absence of a murmur does not rule out CHD. •• Every neonate should have pulse oximetry performed before discharge from the newborn nursery because cyanosis in the neonate can be missed. •• A decreased or bounding pulse is never normal and warrants evaluation. •• Dysmorphic features or the presence of other anatomic abnormalities can be markers for CHD. •• Always consider CHD in a “sick neonate.”

Resources for Families •• Congenital Heart Defects (CHDs) (U.S. Centers for Disease Control and Prevention). www.cdc.gov/ncbddd/heartdefects/index.html •• Congenital Heart Defects (American Heart Association). www.heart.org/ HEARTORG/Conditions/CongenitalHeartDefects/Congenital-HeartDefects_UCM_001090_SubHomePage.jsp •• Congenital Heart Defects and CCHD (March of Dimes). www.marchofdimes.org/baby/congenital-heart-defects.aspx 183

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References 1) Centers for Disease Control and Prevention. Data and Statistics for Congenital Heart Disease. www.cdc.gov/ncbddd/heartdefects/data.html. Accessed September 12, 2017 2) Oster ME, Lee KA, Honein MA, Riehle-Colarusso T, Shin M, Correa A. Temporal trends in survival among infants with critical congenital heart defects. Pediatrics. 2013;131(5):e1502–e1508 3) Donofrio MT, Moon-Grady AJ, Hornberger LK, et al; American Heart Association Adults With Congenital Heart Disease Joint Committee of the Council on Cardiovascular Disease in the Young and Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and Council on Cardiovascular and Stroke Nursing. Diagnosis and treatment of fetal cardiac disease: a scientific statement from the American Heart Association. Circulation. 2014;129(21):2183–2242 4) Khoshnood B, Lelong N, Houyel L, et al; EPICARD Study Group. Prevalence, timing of diagnosis and mortality of newborns with congenital heart defects: a population-based study. Heart. 2012;98(22):1667–1673 5) Mahle WT, Martin GR, Beekman RH III, Morrow WR; Section on Cardiology and Cardiac Surgery Executive Committee. Endorsement of Health and Human Services recommendation for pulse oximetry screening for critical congenital heart disease. Pediatrics. 2012;129(1):190–192 6) Valmari P. Should pulse oximetry be used to screen for congenital heart disease? Arch Dis Child Fetal Neonatal Ed. 2007;92(3):F219–F224 7) Tanner K, Sabrine N, Wren C. Cardiovascular malformations among preterm infants. Pediatrics. 2005;116(6):e833–e838 8) Øyen N, Diaz LJ, Leirgul E, et al. Prepregnancy diabetes and offspring risk of congenital heart disease: a nationwide cohort study. Circulation. 2016;133(23):2243–2253 9) Platt LD, Koch R, Hanley WB, et al. The international study of pregnancy outcome in women with maternal phenylketonuria: report of a 12-year study. Am J Obstet Gynecol. 2000;182(2):326–333 10) Burn J, Brennan P, Little J, et al. Recurrence risks in offspring of adults with major heart defects: results from first cohort of British collaborative study. Lancet. 1998;351(9099):311–316 11) Bull C; British Paediatric Cardiac Association. Current and potential impact of fetal diagnosis on prevalence and spectrum of serious congenital heart disease at term in the UK. Lancet. 1999;354(9186):1242–1247 12) Carvalho JS, Allan LD, Chaoui R, et al; International Society of Ultrasound in Obstetrics and Gynecology. ISUOG Practice Guidelines (updated): sonographic screening examination of the fetal heart. Ultrasound Obstet Gynecol. 2013;41(3):348–359 13) Mahle WT, Newburger JW, Matherne GP, et al; American Heart Association Congenital Heart Defects Committee of the Council on Cardiovascular Disease in the Young, Council on Cardiovascular Nursing, and Interdisciplinary Council on Quality of Care and Outcomes Research; American Academy of Pediatrics Section on Cardiology and Cardiac Surgery; Committee on Fetus and Newborn. Role of pulse oximetry in examining newborns for congenital heart disease: a scientific statement from the AHA and AAP. Pediatrics. 2009;124(2):823–836 14) Jones RW, Baumer JH, Joseph MC, Shinebourne EA. Arterial oxygen tension and response to oxygen breathing in differential diagnosis of congenital heart disease in infancy. Arch Dis Child. 1976;51(9):667–673 15) Johnson C. Fallot’s tetralogy: a review of the radiological appearances in thirty-three cases. Clin Radiol. 1965;16:199–210

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PART 3

Congenital Heart Disease 13. Fetal and ­Newborn Transitional C ­ irculations....................... 187 14. Neonatal Screening for Heart Disease.................................. 197 15. Surgical Procedures for Congenital Heart Disease............... 205 16. Office Care of the Child After Cardiac Surgery................... 237 17. Common ­Syndromes ­Associated With Cardiac Lesions...... 245 18. Adults With ­Congenital Heart Disease............................... 269 19. Congenital Heart Lesions.................................................... Aortic Valve ­Problems, ­Including Bicuspid Aortic Valve and ­Subaortic Membranes.......................................... Atrial Septal Defects............................................................ Atrioventricular Canal Defects............................................. Coarctation of the Aorta...................................................... “Congenitally ­Corrected” ­Transposition of the Great ­Arteries....................................................................... Mitral Valve Anomalies........................................................ Patent Ductus Arteriosus..................................................... Patent Foramen Ovale..........................................................

287 287 292 296 300 305 308 311 314 185

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Pulmonary Stenosis.............................................................. Single-Ventricle Lesions....................................................... Systemic and Pulmonary Vein Anomalies............................ Tetralogy of Fallot................................................................ Transposition of the Great Arteries...................................... Tricuspid Valve Anomalies................................................... Truncus Arteriosus............................................................... Vascular Rings and Slings..................................................... Ventricular Septal Defects....................................................

316 320 325 329 334 339 343 347 353

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CHAPTER 13

Fetal and ­Newborn Transitional ­Circulations James H. Moller, MD, FAAP

Introduction Understanding of the fetal circulation and the transitions that occur with and after birth is beneficial to pediatricians and other practitioners who care for newborns as part of their normal practice. From their subspecialty perspectives, neonatologists and pediatric cardiologists use this information to address the problems that their newborn patients face as they adjust to being born. For neonatologists, conditions such as persistent fetal circulation and pulmonary hypertension represent abnormal transition to the neonatal circulation and to normal neonatal changes in the lungs. For cardiologists, the ductus arteriosus, for example, is critical in several anomalies, where it has helped maintain the fetal circulation, but with its postnatal closure, cardiac manifestations quickly develop. These anomalies include tetralogy of Fallot (TOF) with pulmonary atresia, transposition of the great arteries (TGA), and obstructions to left ventricular (LV) outflow (eg, coarctation). As the ductus closes in these anomalies, the sole source of pulmonary blood flow is eliminated, an avenue for mixing disappears, or a vital source of blood to the aorta is cut off, respectively. Abnormalities in the pattern of fetal blood flow may also affect the formation of the cardiac structures and major blood vessels. This maldevelopment can lead to a cardiac malformation. These various anomalies can be identified during pregnancy by using fetal echocardiography. The anatomic information obtained with 187

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echocardiography, combined with knowledge of the malformations and their effects on the circulation, are useful to practitioners and allow them to anticipate which neonates will need urgent care soon after birth and plan accordingly. Much of our knowledge about the fetal circulation and its transition has been from the study of fetal and neonatal lambs. Rudolph and coworkers at the University of California, San Francisco, have performed numerous sophisticated studies of fetal lambs at various developmental stages and also in the neonatal period.1-3 These have helped define and quantify the volume and direction of blood flow through the heart and great vessels during this time period. In this chapter, this information is combined with previous studies to present an overview. Advances in fetal echocardiography4,5 are expanding our knowledge of the human fetal circulation and its differences from circulation in fetal lambs.

Distinct Features of the Fetal Circulation The fetal circulation functions in parallel, since both ventricles eject blood into the aorta—the LV directly into the ascending aorta and the right ventricle (RV) through the ductus arteriosus into the descending aorta (see Figure 13-1). The combined fetal cardiac output from the ventricles is about 450 mL/kg/ min in both lambs and humans.4 After birth, as the patent ductus arteriosus (PDA) closes and the lungs expand, the neonatal circulation transitions to function as a series circulation. After this transition, the RV ejects only into the pulmonary artery and the LV receives pulmonary venous blood, which it ejects only into the aorta. This transition occurs as the unique features of the fetal circulation disappear. There are 5 distinct features of the fetal circulation that will change at or shortly after birth as the fetal circulation transitions to the neonatal circulation: ductus venosus, foramen ovale, PDA, placental and fetal circulation, and lungs.

Ductus Venosus To understand the venous blood flow in the fetus below the diaphragm, it is helpful to review each of the 5 major abdominal venous pathways. The inferior vena cava receives blood from the lower extremities and kidneys on its path to enter the right atrium. Just below the diaphragm, it receives the hepatic veins carrying blood flow from the liver. The left and right hepatic veins drain blood from the 2 hepatic lobes. The portal venous system carries blood from the intestines and spleen into the liver. The well-oxygenated umbilical venous blood flows from the placenta, and about half of its blood flows into the left and right lobes of the liver. Finally, the ductus venosus extends on the undersurface of the liver, receiving blood only from the umbilical vein, and passes to the inferior vena cava. The umbilical vein as it passes from the placenta first gives rise to branches to the left hepatic lobe, then continues rightward to the portal vein entering the 188

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Superior vena cava

Aorta

Right pulmonary artery

Ductus arteriosus Left pulmonary artery

Right lung

Left lung

Right pulmonary vein Foramen ovale

Left pulmonary vein Pulmonary trunk

Inferior vena cava

Liver Ductus venosus

Descending aorta

Umbilical vein From placenta To placenta

Umbilical arteries

FIGURE 13-1. Diagram of fetal circulation. Reprinted with permission from http://www.heart. org/HEARTORG/Conditions/CongenitalHeartDefects/SymptomsDiagnosisofCongenitalHeart Defects/Fetal-Circulation_UCM_315674_Article.jsp#.WYSkuFGQyUk. ©2017 American Heart Association, Inc.

right hepatic lobe.6-8 About half of umbilical venous blood passes through the ductus venosus directly to the inferior vena cava without passing through the hepatic vascular bed. This portion has a higher oxygen content than the other half, which flows through the right hepatic lobe and passes through the hepatic vascular bed. There is considerable streaming of these 2 halves. Little mixing occurs in the inferior vena cava. The blood from the ductus venosus and the left hepatic vein flows in the posterior and left side of the inferior vena cava and predominantly through the foramen ovale into the left atrium.9,10 From there, it passes through the LV to the ascending aorta and the upper part of the body, most importantly the brain. A small portion goes through the aortic arch to the descending aorta. As a result, the blood from the right hepatic veins, the distal 189

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inferior vena cava, and the superior vena cava passes almost exclusively through the RV into the pulmonary artery. Most of this desaturated blood flows through the PDA to the descending aorta. The oxygen saturation of this blood is lower than that in the ascending aorta. A large portion of this transductal blood flow is directed into the placenta, which is the fetal site of oxygenation.

Foramen Ovale The foramen ovale provides the opening in the atrial septum, allowing blood flow from the right to the left atrium. The atrial septum is formed by 2 embryological septae. The septum primum develops and, as it completes its separation of the left atrium from the right atrium, an opening develops in its center. This opening is called the ostium secundum. A second septum, the septum secundum, then develops on the right side of the septum primum. It forms on the superior and posterior right atrial wall and progressively extends inferiorly and anteriorly as a crescent to cover the ostium secundum. The slightly thickened edge of this septum is called the limbus of the fossa ovalis; the atrial septum below appears as an oval fossa, also called fossa ovalis. During fetal life, the septum primum and septum secundum are not fused. They may or may not overlap, but they leave a space between them or allow a small (up to 4 mm) opening between the atria. Since right atrial pressure exceeds left atrial pressure in the fetus, blood flows right to left through the foramen ovale. In about three-quarters of all individuals, the foramen ovale closes anatomically during the first year of life, but in about a quarter of individuals, it remains patent throughout life. In this instance, it is known as a “patent foramen ovale.”

Patent Ductus Arteriosus The ductus arteriosus is a remnant of the sixth left embryonic aortic arch. There are both right and left sixth aortic arches, but the right regresses early during fetal development. The sixth left arch originates from the proximal left pulmonary artery at its junction with the main pulmonary artery and extends posteriorly and inferiorly to the dorsal aorta beyond the origin of the left subclavian artery but proximal to the first intercostal arteries. At birth, its diameter is the same as that of the main pulmonary artery and dorsal aorta. Its wall thickness is the same as in these 2 major arteries. In contrast, however, its media is composed of smooth muscle rather than elastic fibers, as in the aorta and branch pulmonary arteries. The contraction of these smooth muscles closes the ductus normally during the first day after birth. Three factors contribute to maintaining patency of the ductus during fetal life: low fetal partial pressure of oxygen (Po2) levels, circulating prostaglandins, and nitric oxide from endothelial cells. Since the placenta, rather than the lungs, is the organ of gas exchange prior to birth, most of the blood entering the main pulmonary artery passes from right to left through the ductus into the descending aorta. The aortic and pulmonary 190

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arterial pressures are identical. The direction and magnitude of blood flows are determined by the relative systemic and pulmonary vascular resistances. Because the placenta is essentially an arteriovenous fistula, its resistance is low when compared to the increased pulmonary vascular resistance. The RV ejects about 65% of the combined cardiac output (combination of LV and RV outputs). Of this, approximately 55% flows into the aorta and 8% to 10% flows into the pulmonary arteries to meet the metabolic requirements of the lungs.

Placental and Fetal Circulation The placenta acts like a large arteriovenous fistula and thus has a low vascular resistance. With progressive gestational age, the size of the placenta and its blood flow requirements increase proportionately. About 40% of the combined fetal cardiac output goes to the placenta. This represents about 60% of the blood flow through the ductus arteriosus. The placenta receives blood from 2 individuals, the mother and the fetus. It has 2 components, the maternal placenta and the fetal placenta. These are attached by villi. The chorionic villi provide a large area where fetal blood comes close to the maternal blood and exchange of gases occurs. The maternal blood flows through endometrial arteries into the intervillous space, and its venous blood exits through endometrial veins. The umbilical arteries divide into an extensive network of small vessels, including capillaries. It is at this level that gas is exchanged. The adjacent venous networks coalesce into the umbilical vein, which courses alongside the umbilical arteries toward the fetus to enter the ductus venosus.

Lungs During fetal life, the lungs are collapsed and airless. Because of the low-oxygen environment in the fetus, the pulmonary vascular resistance is increased from arteriolar vasoconstriction. The pulmonary arterioles in the fetal lung have a thick medial coat and a narrow lumen. Therefore, the volume of pulmonary blood flow is limited (1,000 mg/dL (11.3 mmol/L). Although the exact mechanism that causes pancreatitis is not fully known, it is thought that chylomicrons and their remnants impede pancreatic capillary blood flow, resulting in ischemic disruption in the acinar structure, inflammation, edema, and necrosis. Because hypertriglyceridemia is often accompanied by low HDL and increased small dense LDL, it is also associated with increased risk of premature cardiovascular disease. This may be especially true in individuals with other cardiovascular disease risk factors, such as obesity, insulin resistance or diabetes, and a history of smoking.

Evaluation A standard lipid panel (total cholesterol, triglycerides, HDL cholesterol, and LDL cholesterol), obtained with or without fasting, is recommended as an initial screening test. A nonfasting sample is often more practical and convenient. However, since caloric intake can often increase triglyceride levels, in those with a triglyceride level above 200 mg/dL (2.26 mmol/L), a fasting sample is often more informative. Blood samples can be drawn via venipuncture or finger stick. If available, point-of-care lipid testing (eg, tabletop analyzer) has proven reliable and correlates well with standard laboratory results. 556

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Table 34-6. Drugs That May Cause Dyslipidemia LDL Cholesterol

Triglycerides

HDL Cholesterol

Estrogen

↓ 7%–20%

↑ 40%

↑ 5%–20%

Some progestins

↑ variable

↓ variable

Selective estrogen receptor modulators

↓ 10%–20%

↑ 0%–30%

Danazol

↑ 10%–40%



↓ 50%

Protease inhibitors

↑ 15%–30%

↑ 15%–200%



Anabolic steroids

↑ 20%



↓ 20%–70%

Retinoids

↑ 15%

↑ 35%–100%

↔b

↑ 10%–25%



0–↑7%

Corticosteroids

↑ variable

↑ variable



Immunosuppressive drugs (­cyclosporine and tacrolimus)

↑ 0%–50%

↑ 0%–70%

↑ 0%–90%

Thiazide diuretics (high dose)

↑ 5%–10%

↑ 5%–15%



Loop diuretics

↑ 5%–10%

↑ 5%–10%





↑ 10%–40%

↓ 5%–20%

↑ variable





First-generation antipsychotics



↑ 22%

↓ 20%

Second-generation antipsychotics



↑ 20%–50%



↑ variable



↑ variable

Growth hormone

β-blockers

c

Amiodarone

Anticonvulsants

↓ 15%–40% ↔

a

↓, decreased; ↑, increased; ↔, no change; HDL, high-density lipoprotein; LDL, low-density lipoprotein. Raloxifene has not been shown to increase triglyceride levels, while increases of up to 30% have been reported with the use of tamoxifen. Data remain conflicting; some evidence shows a decrease, no effect, or increase. c Varies on the basis of the individual drug. a

b

From Herink M, Ito MK. Medication induced changes in lipid and lipoproteins. In: De Groot LJ, Chrousos G, Dungan K, et al, eds. Endotext. South Dartmouth, MA: MDText.com; 2000.

When increased levels of lipids and lipoproteins are encountered, secondary causes of dyslipidemia should be excluded, such as hypothyroidism, liver and kidney diseases, and use of a variety of medications. Laboratory data should be combined with pertinent history and physical findings to help determine the most likely etiologic origin. The possibility of an underlying genetic disorder of lipid metabolism, expressed or exacerbated by a secondary cause, should always be considered. Children with highly increased triglyceride levels (generally >1,000 mg/dL [11.3 mmol/L]) are at high risk of having a monogenic mutation. While testing 557

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is available, confirmation of a genetic mutation is not necessary for initiation of therapy. Genetic testing may be critical, however, in those who are candidates for targeted therapies (ie, gene therapy).

Treatment Maintaining a heart-healthy lifestyle, characterized by an age-appropriate diet, daily physical activity, maintaining a healthy weight, and avoiding smoking, is key to avoiding premature cardiovascular disease and diabetes. Dietary guidelines for Americans are shown in Box 34-1. A Cardiovascular Health Integrated Lifestyle triglyceride-lowering diet should be provided for all children with increased triglyceride levels.8 This diet includes reduction of added sugars and simple carbohydrates, along with reduction of intake of saturated fat. When obesity is present, a decrease of total calories is a cornerstone of comprehensive weight management. Increased physical activity, including increasing moderately vigorous physical activity to at least 60 minutes per day, improves vascular function and insulin sensitivity. Dietary management should be guided by a registered dietitian, when available. In children who present with acute pancreatitis, intravenous hydration and pain management remain the mainstays of medical management. Once stable, children should be advanced to a fat-restricted diet.

Box 34-1. 2015–2020 Dietary Guidelines for Americans at a Glance Five Guidelines That Encourage Healthy Eating Patterns: 1. Follow a healthy eating pattern across the lifespan. All food and beverage choices matter. Choose a healthy eating pattern at an appropriate calorie level to help achieve and maintain a healthy body weight, support nutrition adequacy, and reduce the risk of chronic disease. 2. Focus on variety, nutrient density, and amount. To meet nutrient needs within calorie limits, choose a variety of nutrient-dense foods across and within all food groups in recommended amounts. 3. Limit calories from added sugars and saturated fats and reduce sodium intake. Consume an eating pattern low in added sugars, saturated fats, and sodium. Cut back on foods and beverages higher in these components to amounts that fit within healthy eating patterns. 4. Shift to healthier food and beverage choices. Choose nutrient-dense foods and beverages across and within all food groups in place of less healthy choices. Consider cultural and personal preferences to make these shifts easier to accomplish and maintain. 5. Support healthy eating patterns for all. Everyone has a role in helping to create and support healthy eating patterns in multiple settings nationwide, from home to school to work to communities. From https://health.gov/dietaryguidelines/2015/guidelines/executive-summary/#figure-es-1.

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In children with monogenic disorders (eg, LPL deficiency) and triglyceride levels above 1,000 mg/dL (11.3 mmol/L), standard lipid-lowering therapies, such as omega-3 fatty acids, niacin, and fibrates, are generally ineffective. Successful management requires restricting dietary fat to 15% of the total daily caloric intake. If triglyceride levels are not lowered to goal levels, further dietary fat restriction may be necessary while ensuring that essential fatty acid needs are met (2%–4% of total calories as linoleic acid). If tolerated, the fat-restricted diet may include 10% to 15% calories from short- and long-chain fat, 60% calories from complex carbohydrates, and 25% to 30% calories from protein, while avoiding concentrated carbohydrates. Medium-chain triglycerides may be helpful in providing essential fatty acids and additional calories. Adequate intake of fat-soluble vitamins (A, D, E, and K) should be monitored. Novel treatments, including gene and anti–apoC-III therapies, are currently in clinical development. For children with less severe hypertriglyceridemia (