Left to Right Shunts - ECAB 9788131217221, 9788131231746, 8131231747

Table of contents :
Front Cover
Title page
Elsevier Clinical Advisory Board:Cardiology
Copyright
About the Authors
Contents
ECAB Clinical Update Information
Introduction
Natural History of Left to Right Shunts
Atrial Septal Defect
Spontaneous Closure
Pulmonary Hypertension and Pulmonary Vaso-Occlusive Disease
Heart Failure
Atrial Arrhythmias
Repaired ASD
Patent Foramen Ovale
Mortality
Atrioventricular Septal Defect
Natural History of Ventricular Septal Defect
Spontaneous Closure
Pulmonary Vascular Disease
Infective Endocarditis
Mortality
Aortic Regurgitation
Infundibular Pulmonary Stenosis
Patent Ductus Arteriosus
Spontaneous Closure
Congestive Heart Failure
Pulmonary Hypertension
Endarteritis
Aneurysm of Ductus Arteriosus
Mortality
Hemodynamic Assessment of Congenital Heart Defects with Left to Right Shunts and Pulmonary Hypertension
Introduction
Objectives of the Review
Correlating Pre-Operative Hemodynamics with Lung Biopsy Findings and Clinical Outcomes
Clinical and Non-Invasive Correlates of Hemodynamic Changes in Left to Right Shunts
Accurate Hemodynamic Assessment in Shunt Lesions: Who Needs it Most?
Role of Clinical Examination, Ecg, Chest X-ray, Echocardiography and Arterial Blood Gas
Hemodynamic Assessment in the Catheterization Laboratory
Correct Sequence of Sampling and Pressure Measurement
Calculation of Flows and Resistances
Common Sources of Error with Invasive Hemodynamic Assessment
Role of Reversibility Testing for Estimation of Operability
Conclusion
Surgery in Congenital Heart Disease with Left to Right Shunts
Introduction
Timing of Surgical Intervention: Broad Principles
Predicting the Natural History of Congenital Heart Disease
Precise Anatomic Diagnosis
Hemodynamic Assessment
Clinical Evaluation
Natural History Information
Spontaneous Closure of Defects
Procedural Outcome
Guidelines for Individual Lesions
The Effect of Co-morbidities
Surgical Operations for Left to Right Shunts
Pulmonary Artery Banding
Technique
Patent Ductus Arteriosus
Atrial Septal Defects
Partial Anomalous and Hemianomalous Pulmonary Venous Connections
Ventricular Septal Defects
Atrio-ventricular Canal
Postoperative Features
Aorto-pulmonary Window
Conclusions
Summary
Forthcoming Books

Citation preview

ECAB Clinical Update: Cardiology Left to Right Shunts

ECAB Clinical Update: Cardiology Left to Right Shunts Nagaraj Desai R. Krishna Kumar K. Shivaprakasha Prabhakar Koregol Rahul K. Singh Sangeetha Viswanathan Editor: Nagaraj Desai

Elsevier Clinical Advisory Board: Cardiology Dr. Rabin Chakraborty, MD, DNB, FRCP, FICC, FISE, DM

Apollo Hospitals, 21 Greams Lane, Off Greams Road, Chennai.

Chief of Cardiology, Apollo Gleneagles Hospitals, 58, Canal Circular Road, Kolkata.

Dr. Ashok Seth, FRCP (Lond.), FRCP (Edin.), FRCP (Irel.), FACC, FSCAI, DSc (HONORIS CA, USA)

Dr. Nagaraj Desai, MD, DM, FACC, FICC Director & Senior Consultant, Dept. of Cardiology, Apollo Hospitals, Bannerghatta Road & Seshadripuram, Bangalore.

Dr. M.R. Girinath, MCh, FRACS Chief Cardio-Vascular Surgeon, Dept. of Cardio-Vascular Surgery, Apollo Hospitals, 21 Greams Lane, Off Greams Road, Chennai.

Dr. Ravi R. Kasliwal, MD, DM, FIMSA, MNAMS Senior Consultant Cardiologist, Global Health Group Pvt. Ltd., Indraprastha Apollo Hospital, Mathura Road, New Delhi. Director, Cardiology & Community Outreach Program.

Dr. R. Krishna Kumar, MD, DM, FACC, FAHA Clinical Professor and Chief Pediatric Cardiologist, Amrita Institute of Medical Sciences, Kochi.

Dr. Satish K. Parashar, MD, FCCP Senior Consultant Cardiologist, Metro Heart Institute, Lajpat Nagar-IV, New Delhi.

Dr. I. Sathyamurthy, MD, DM, FACC, FRCP (Edin.), FRCP (Glas.) Director, Dept. of Cardiology,

Chairman & Chief Cardiologist Max Heart and Vascular Institute Press Enclave Road, Saket, New Delhi.

Dr. Devi P. Shetty, MS Chairman & Senior Consultant Cardiac Surgeon, Narayana Hrudayalaya, No. 258/A, Bommasandra Industrial Area, Anekal Taluk, Bangalore.

Dr. Nakul Sinha, MD, DM, FACC, FSCAI Professor and Head, Department of Cardiology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow.

Dr. Naresh Trehan, Diplomate, American Board of Surgery, Diplomate, American Board of Cardiothoracic Surgery Chairman and Chief Cardiothoracic & Vascular Surgeon, Global Health Pvt. Ltd., Indraprastha Apollo Hospital, Mathura Road, New Delhi.

Dr. O.P. Yadava, MS, DNBE (Gen. Surg.), DNBE (Cardio Vascular Thoracic Surg), MNAMS, FICC, FIACS C.E.O. & Chief Cardiac Surgeon, National Heart Institute, East of Kailash, New Delhi.

ECAB CLINICAL UPDATE: CARDIOLOGY LEFT TO RIGHT SHUNTS

CONTRIBUTORS Dr. Dr. Dr. Dr. Dr. Dr.

Nagaraj Desai R. Krishna Kumar K. Shivaprakasha Prabhakar Koregol Rahul K. Singh Sangeetha Viswanathan

ELSEVIER INDIA HEALTHCARE COMMUNICATIONS DIRECTOR Mr. Vidhu Goel

EDITOR Dr. Nagaraj Desai

ELSEVIER PUBLISHING TEAM Dr. Lalit Singh Manager - Content Development

Ms. Bobby Choudhury Content Designer and Editor

EDITORIAL OFFICE Logix Park, First Floor, A4 & A5, Sector-16, NOIDA, U.P. - 201301, India Telephone: + 91-120-4679200 Fax: + 91-120-4679201 E-mail: [email protected]

Elsevier Clinical Advisory Board: Cardiology

ELSEVIER A division of Reed Elsevier India Private Limited

Copyright © 2008 Elsevier Mosby, Saunders, Churchill Livingstone, Butterworth Heinemann and Hanley & Belfus are the Health Science imprints of Elsevier. 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 the prior permission of the copyright holder. Medical knowledge is constantly changing. As new information becomes available, changes in treatment, procedures, equipment, and the use of drugs become necessary. The authors, editors, contributors, and the publisher have, as far as possible, taken care to ensure that the information given in this text is accurate and up-to-date. However, readers are strongly advised to confirm that the information, especially with regard to drug dose/usage, complies with current legislation and standard of practice. Opinions expressed in this book are those of the authors and do not necessarily reflect those of Elsevier India Pvt. Ltd., the editors, or sponsors. Elsevier India Pvt. Ltd. assumes no liability for any material published herein.

ISBN 978-81-312-1722-1 Published by: Elsevier, a division of Reed Elsevier India Private Limited Logix Park, First Floor, A4 & A5, Sector-16, NOIDA, U.P. - 201301, India Typeset at PC Docs, New Delhi Printed at Saurabh Printers, New Delhi

About the Authors Dr. Nagaraj Desai is the Director and Senior Consultant, Department of Cardiology, Apollo Hospitals, Bangalore. He also held the post of Professor and Head, Department of Cardiology at M.S. Ramaiah Medical College and the Director, Ramaiah Heart Center at M.S. Ramaiah Memorial Hospital, Bangalore, till recently. He presented and published more than 75 abstracts and 25 papers at various levels. Dr. Desai has received Siddarth N. Shah Epidemiology Oration on Hypertension and P.R. Nayak gold medal for contribution toward the growth of cardiovascular sciences in Karnataka. He is on the editorial board of Karnataka Medical Journal and on the Indian edition of Journal of the American College of Cardiology. He is the member of several national and international societies and the fellow of American College of Cardiology and Indian College of Cardiology. Dr. Desai has served as the President of Cardiological Society of India. Dr. Desai’s areas of interest include Coronary Artery Disease, Myocardial Reperfusion, and Adult Cardiac Intervention Procedures. Dr. R. Krishna Kumar is currently serving as the chief pediatric cardiologist at the Amrita Institute of Medical Sciences, Kochi, Kerala. He has also served as Consultant Cardiologist (Pediatric Cardiology) at Escorts Heart Institute & Research Centre, New Delhi. He has valuable contribution in over 80 national as well as international publications. Dr. Kumar has presented his papers at several conferences, both in India and abroad. He is among the pioneers in India in the field of CME. His major interest is in Pediatric Heart Disease in Developing Countries, Development of Inexpensive Devices and Strategies for catheter Interventions, and Education through Development of Teaching/Training Software for Cardiovascular Imaging. Dr. Shiva Prakash K. is serving as senior consultant pediatric cardiac surgeon and clinical professor in department of cardiothoracic surgery at Amrita Institute of Medical Sciences, Kochi, Kerala. He is active member of various medical societies and is the founder member of Pediatric Cardiac Society of India. Dr. Shiva Prakash’s areas of academic and clinical interest

ECAB Clinical Update: Cardiology



About the Authors

include congenital heart disease in the developing countries, valve reconstruction in children, neonatal cardiac surgery and cosmetic congenital heart surgery. He has published his research work in numerous national and international journals. He has also received Best Paper awards at various conferences for his contributions on congenital heart surgery.

ECAB Clinical Update: Cardiology Left to Right Shunts

Contents ECAB Clinical Update Information ..................................... i Introduction ........................................................................... 1 Dr. Nagaraj Desai

Natural History of Left to Right Shunts ............................. 4 Dr. Nagaraj Desai, Dr. Prabhakar Koregol and Dr. Rahul K. Singh

HemodynamicAssessment of Congenital Heart Defects with Left to Right Shunts and Pulmonary Hypertension ............................................... 20 Dr. R. Krishna Kumar and Dr. Sangeetha Viswanathan

Surgery in Congenital Heart Disease with Left to Right Shunts ........................................................... 45 Dr. K. Shivaprakasha and Dr. R. Krishna Kumar

Summary .............................................................................. 74 Dr. Nagaraj Desai

Forthcoming Books ............................................................. 76

ECAB Clinical Update Information

Left to Right Shunts ELSEVIER CLINICAL ADVISORY BOARD (ECAB) INDIA ECAB is an endeavor of Elsevier, the leading publishing house worldwide in health sciences, with an aim to develop relevant content in clinical specialties and make them easily available to the medical professionals of India. ECAB plans to include a vast range of clinical specialties like diabetes, cardiology, gastroenterology, and obstetrics & gynecology. ECAB plans to explore the experience and learning of some of the eminent medical professionals of India in their respective fields in addition to its own existing resources to create its content, which is available in the form of various products and services for utilization by the Indian clinical practitioners. This concept is a first of its kind in the Indian medical scenario, and ECAB will extend this to every clinical discipline to serve the information needs of the Indian medical fraternity.

STATEMENT OF NEED Congenital malformations of heart and great vessels result from certain defects in normal developmental process. They are not so uncommon with literature from western countries suggesting 1 case in every 100 live births. No specific data on their incidence is available from India but the incidence is believed to be higher in developing countries. Up to 75% of these malformations fall in the category of acyanotic defects and result in left to right shunting of blood. The most common of these defects are Ventricular septal defects (VSD), Patent ductus arteriosus (PDA), Atrial septal defect (ASD) and Atrio-ventricular septal defect (AVSD), in that order of occurrence. The severity of symptoms varies according to the size and nature of the defects. These malformations follow a typical natural history, whereby smaller defects usually close by themselves and the larger ones become symptomatic and at times, lead to congestive heart failure in childhood. This results in huge economic burden on the parents as well on the country. In the backdrop of this prevailing scenario, proper evaluation, work-up and timely treatment of the patients is of utmost importance. There is a strong need for a clear understanding of natural history of these shunts i

ECAB Clinical Update: Cardiology



Information

and of various available treatment options. This also demands formulation of strategies, keeping in mind the conditions in India and the experience of the specialists from India. In its quest to better address this need in India, Elsevier has pooled its existing resources with those of the internationally acclaimed cardiologists/cardiac surgeons of India who have chosen to apply their rich clinical knowledge and expertise to serve the future Indian generations.

LEFT TO RIGHT SHUNTS Patients born with cardiac defects need to be identified early and the severity of symptoms also needs to be identified. In children with larger defects or with more symptoms, early institution of treatment is warranted, since in absence of treatment, the disease progresses to pulmonary hypertension and a simple pathology gets complicated. Presence of congestive cardiac failure in infancy or of pulmonary artery hypertension is indication for early surgical treatment (prior to 6 months of age). Untreated ASD may at times allow the child to grow and reach adulthood, but can cause complications in adulthood also. These issues related to understanding of natural history of the shunts and its implications in management decisions need to be addressed in clear terms. Also the role and timing of surgical therapy need to be emphasized. This book is designed to address such questions with supportive clinical scenarios. Thus, it provides an excellent opportunity to widen one’s perspective in this area.

TARGET AUDIENCE This book is intended for the Indian cardiologists, cardiothoracic surgeons, pediatricians, advanced practitioners and other health care professionals interested in treatment of congenital heart diseases.

EDUCATIONAL OBJECTIVES Readers will find the contents useful to:  Get an insight into natural history of these common congenital heart diseases.  Understand the protocols for diagnostic and hemodynamic work-up of these patients.  Know the indications of surgical treatment and the various available surgical options.

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Information



ECAB Clinical Update: Cardiology

ACCREDITATION INFORMATION The Elsevier Clinical Advisory Board (ECAB): Cardiology designates this educational activity for a maximum of 6:00 hours requirements judged by the board to be equivalent to the same number of AMA PRA credit hours.

DISCLAIMER The content and views presented in this book are those of the contributors and do not necessarily reflect the opinions or recommendations of the whole ECAB or Elsevier. The content has been prepared based on a review of multiple sources of information, but is not exhaustive of the subject matter. Readers are advised to critically evaluate the information presented, and are encouraged to consult the available literature on any product or device mentioned in the content.

DISCLOSURE OF UNLABELED USES This book may contain discussion of published and/or investigational uses of agents that are not approved by the Food and Drug Administration. Please consult relevant literature for information about approved uses.

DISCLOSURE OF FINANCIAL RELATIONSHIPS WITH ANY COMMERCIAL INTEREST As a provider of credible content, Elsevier requires that everyone is in a position to control the content of an educational activity disclose all relevant financial relationships with any commercial interest, and identify and resolve all conflicts of interest prior to the educational activity. The ECAB defines “relevant financial relationships” as any amount occurring within the past 12 months. Financial relationships are those relationships in which the individual benefits by receiving a salary, royalty, intellectual property rights, consulting fee, honoraria, ownership interest (e.g., stocks, stock options, or other ownership interest, excluding diversified mutual funds), or other financial benefit. Financial benefits are usually associated with roles such as employment, management position, independent contractor (including contracted research), consulting, speaking and teaching, membership on advisory committees or review panels, board membership, and other activities for which remuneration is received or expected. The ECAB considers relationships of the person involved in the educational activity to include financial relationships of a spouse or partner.

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For an individual with no relevant financial relationship(s), the participants must be informed that no relevant financial relationship(s) exist.

RESOLUTION OF CONFLICT OF INTEREST The ECAB has implemented a process to resolve conflict of interest for each book. In order to help ensure content objectivity, independence, and fair balance, and to ensure that the content is aligned with the interest of the intended audience, the ECAB has the evaluation of content done by those members of ECAB who are not directly involved in the project.

CONTENT DEVELOPMENT COMMITTEE Dr. Nagaraj Desai, MD, DM, FACC, FICC Dr. R. Krishna Kumar, MD, DM, FACC, FAHA Dr. K. Shivaprakasha, MS, McH Dr. Prabhakar Koregol, MD, DM Dr. Rahul K. Singh, MD Dr. Sangeetha Viswanathan, MRCPH Dr. Lalit Singh, MS Ms. Bobby Choudhury

ENQUIRIES For all content-related enquiries, please contact us at [email protected].

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Introduction Congenital malformations of heart and great vessels result from certain defects in normal developmental process. They are not so uncommon with literature from western countries suggesting 1 case in every 100 live births. No specific data on their incidence is available from India but the incidence is believed to be higher in developing countries. Up to 75% of these malformations fall in the category of acyanotic defects and result in left to right shunting of blood. In the normal heart, the right side pumps deoxygenated blood to the lungs, whilst the left side pumps the oxygenated blood all around the body. The pressure in the left ventricle (pumping chamber) is generally about four times that in the right ventricle and the wall of the left ventricle is thicker than that of the right. Congenital defects of the inter-atrial and inter-ventricular septa allow blood to flow (shunt) from the high pressure left side of the heart to the lower pressure right side. This results in an increase in the pressure on the right, and causes too much blood to be pumped to the lungs. The body’s natural reaction to this event is to constrict (narrow) the blood vessels in the lungs in an effort to limit this excess blood flow. Over a period of time, this narrowing of the pulmonary (lung) arteries increases due to thickening in the surrounding muscle due to the increased workload, and also the closure of smaller lung arteries. These changes reduce the blood flow into the lungs, and increase the pressure needed by the right ventricle to pump blood into the lungs to be oxygenated. As the resistance to flow increases, left to right shunting of blood is reduced and eventually the shunt is reversed, i.e. right to left shunting of blood starts. These changes in pulmonary vascular tree are collectively called pulmonary vascular disease, and ultimately results in low oxygen levels and therefore, cyanosis. The rate of development of pulmonary vascular disease depends on the nature and size of the defect, but varies greatly from patient to patient, even between those with the same cardiac problem. Careful clinical evaluation including non-invasive techniques should be employed to assess the patient especially if the patient is seen first time or is on follow-up. Cardiac catheterization and angiocardiography have long been the most definitive techniques for the anatomic and hemodynamic assessment of congenital heart disease. During the past decade, however, non-invasive imaging modalities such as 2-dimensional echocardiography, magnetic 1

ECAB Clinical Update: Cardiology



Introduction

resonance imaging (MRI), and radionuclide scintigraphy are being utilized more often, which has resulted in decrease in necessity for invasive catheterization to evaluate congenital heart lesions, thereby reducing the risks of invasive diagnostic procedures. Echocardiography and MRI have emerged as the dominant methods for the morphologic assessment of congenital heart disease, whereas radionuclide imaging is used primarily for the assessment of cardiac physiology. Although rarely used today for the assessment of right and left ventricular function in pediatric patients, radionuclide studies continue to provide valuable information for the evaluation of intra- and extracardiac shunts, and assessment of myocardial perfusion. However, it may be noted that radionuclides studies (especially in Indian subcontinent) are not used on routine basis as the other easily available modalities are able to answer all clinical questions. Moreover, radionuclide methods often lack sufficient resolution to precisely characterize complex morphology in congenital heart lesions. They provide accurate and reproducible quantitative assessment of the physiological consequences of structural heart disease. Surgical repair is generally carried out fairly early in life, at times within first 6 months of age, although timing of the same is dictated by the defect and its physiological consequences in the patient in question. Successful surgery will usually prevent the continuance of pulmonary hypertension, and the development of pulmonary vascular disease. The damage caused by prolonged pulmonary hypertension generally prohibits late repair of cardiac defects and is in fact, one of the most important contraindications for surgery. The management of patients with pulmonary hypertension and cardiac failure during surgery is complex. Minor stimuli, such as insertion of a peripheral cannula, endotracheal suction and surgical stress can also cause arrhythmias and increase pulmonary vascular resistance. General anesthesia can produce unpredictable reductions in pulmonary blood flow, especially in the presence of chronic cardiac failure. In a young child with pulmonary vascular disease, corrective surgery rarely causes dangerous complications. However, an alternative surgery (if warranted) in such cases can be pulmonary artery banding. This procedure requires the surgeon to place a restrictive band around the artery, thus reducing the blood flow into the lungs, and preventing the need for the body to form its own restriction. If successful, the development of pulmonary vascular disease may be slowed or stopped, and surgical repair of the hole(s) may be possible at a later date. In cases where banding 2

Introduction



ECAB Clinical Update: Cardiology

fails or is found inappropriate, certain medications which relax the pulmonary vessels and increase the blood flow into the lungs, may be tried. These drugs may prove effective at reducing the pulmonary artery pressure. Keeping these facts in mind, timely diagnosis, work-up and surgical treatment of these patients assume a very important role.

Dr. Nagaraj Desai Senior Consultant, Department of Cardiology, Wockhardt Hospitals, Bangalore Director, Namana Medical Centre, Bangalore Former Professor and Head, Department of Cardiology, M.S. Ramaiah Medical College and Hospitals Director, Ramaiah Heart Center

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Natural History of Left to Right Shunts Dr. Nagaraj Desai, MD, DM, FACC, FICC Senior Consultant, Department of Cardiology, Wockhardt Hospitals, Bangalore; Director, Namana Medical Centre, Bangalore; Former Professor and Head, Department of Cardiology, M.S. Ramaiah Medical College and Hospitals; Director, Ramaiah Heart Center

Dr. Prabhakar Koregol, MD, DM Consultant Cardiologist, Wockhardt Hospitals, Bangalore

Dr. Rahul K. Singh, MD Consultant Cardiologist, M.S. Ramaiah Memorial Hospital, Bangalore

ABSTRACT: Left to right shunt lesions are a heterogeneous group of disorders. At one end of the spectrum one finds a condition like an aortopulmonary window which presents early in childhood. The other extreme is the presence of a patent foramen ovale that may reveal itself when one is dealing with a patient who has a stroke. The detection of these conditions may be during systematic examination, but more often than not, is by chance. The natural history of left to right shunt lesions is governed by various factors. The most important, but not the only one, is the degree of shunt. Other important factors are the location of the shunt and the presence of associated cardiac and extra-cardiac abnormalities. A detailed knowledge of the natural history of 4D

these lesions allows one to plan the management strategies for such patients. It would also be beneficial in anticipating complications discussing the prognosis. In this chapter, the atrial, ventricular and the great artery shunts will be discussed.

KEYWORDS: 1. Atrial septal defect 2. Foramen ovale 3. Pulmonary vascular disease 4. Endocarditis

4b

Natural History of Left to Right Shunts Dr. Nagaraj Desai, MD, DM, FACC, FICC Senior Consultant, Department of Cardiology, Wockhardt Hospitals, Bangalore; Director, Namana Medical Centre, Bangalore; Former Professor and Head, Department of Cardiology, M.S. Ramaiah Medical College and Hospitals; Director, Ramaiah Heart Center

Dr. Prabhakar Koregol, MD, DM Consultant Cardiologist, Wockhardt Hospitals, Bangalore

Dr. Rahul K. Singh, MD Consultant Cardiologist, M.S. Ramaiah Memorial Hospital, Bangalore

Left to right shunt lesions are a heterogenous group of disorders. At one end of the spectrum one finds a condition like an aortopulmonary window which presents early in childhood. The other extreme is the presence of a patent foramen ovale, that may reveal itself when one is dealing with a patient who has a stroke. The detection of these conditions may be during systematic examination, but more often than not, is by chance. The pick up rates have significantly improved because of the availability of the sophisticated, non-invasive imaging modalities. However, most of these shunt lesions have a long, protracted, apparently benign course. Systematic studies in these patients have been done in the past, and it is this information that has 4

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Desai, Koregol and Singh

helped us to understand the diseases better. The earliest data was a combination of clinical and autopsy series, but with the advent of echocardiographic techniques, the scenario has changed. At present the treating clinician has, at his disposal, the wisdom generated from the pre-echocardiographic data as well as the knowledge of hemodynamics that can be well assessed on echocardiography. The natural history of left to right shunt lesions is governed by various factors. The most important, but not the only one, is the degree of shunt. Other important factors are the location of the shunt and the presence of associated cardiac and extra cardiac abnormalities. A detailed knowledge of the natural history of these lesions allows one to plan the management strategies for such patients. It would also be beneficial in anticipating complications discussing the prognosis. Some of these defects may at times be part of complex cardiac anomalies, which will not be discussed in this chapter. However, it may be pointed out that in such a case the overall cardiac physiology will determine the clinical status rather than the shunt itself. In this chapter, the atrial, ventricular and the great artery shunts will be discussed in that order.

ATRIAL SEPTAL DEFECT Atrial septal defect (ASD) is classified as secundum, primum and sinus venosus defects according to the location of the defect in the atrial septum. Other varieties of atrial left to right shunts like partial and total anomalous pulmonary venous drainage (or connection) are also discussed, but separately. The Natural history of a left to right following discussion is limited to shunt lesion is governed by the secundum ASD. degree of shunt. The prototype lesion for the discussion will be the ostium secundum ASD. The variations will be discussed separately. The following discussion is limited to secundum ASD.

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ECAB Clinical Update: Cardiology

ASD of secundum variety is a relatively common (6–10% of all CHDs) condition and is correctable either by means of surgery or by using catheter-based devices in suitable cases. It is due to this reason that the natural history of this defect is altered especially if corrected at an appropriate time. The diagnosis of ASD may sometimes be difficult because of paucity of symptoms and signs especially in infancy and childhood. While in the developed economies, it is uncommon to see uncorrected ASD (unless the patient himself belongs to the disadvantaged sections) in the adult, it is not so uncommon to encounter the same in India. This is because of poor health screening systems. It is not uncommon that a child misses the preschool check-up because of non-availability of even basic health amenities especially in disadvantaged sections of society in far off rural regions of the country. It may also be due to lack of initiative by the family or even the health providers. Unless it is large, ASD does not produce any symptoms and it is quite common not to listen to the heart in busy practice thereby missing the opportunity of picking up an ASD. Although school health examination provides yet another opportunity it may not be taken with necessary seriousness.

Most of the large atrial septal defects remain asymptomatic.

The natural history of ASD is, in general, determined by the size of the defect, pulmonary vascular reactivity and myocardial function. It can be discussed under spontaneous closure, symptoms and deterioration of the functional status due to arrhythmias and congestive heart failure (CHF), pulmonary arterial hypertension (PAH) and mortality. As with most of the left to right shunts, study of the natural history is impossible from the current series owing to the correction of the same. Hence we have to depend mostly on the older series, except may be for the spontaneous closure. ASDs generally have relatively a benign course and permit longevity of life. But, the same is not true when ASD is large or when associated with other cardiac defects. 1,2

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Desai, Koregol and Singh

Spontaneous Closure Spontaneous closure of the ASD has been reported with an incidence of 14–66%. 3,4 Spontaneous closure has been documented up to 2–8 years but the mechanism still remains hypothetical and largely unknown. The closure appears to be unrelated to the symptoms, physical findings. The frequency and timing of spontaneous closure is inversely related to the diameter of the ASD in infants younger than 3 months. A recent prospective echocardiographic study by Fukazawa et al suggested as many as 24% of the newborns have an opening at the atrial septal level in the first week of life measuring 3–8 mm and 92% of these close spontaneously in little more than a year. In simpler terms, there is a good chance of spontaneous closure of ASD detected in the newborn period necessitating only follow-up strategy. It is not necessary to intervene.

PULMONARY HYPERTENSION AND PULMONARY VASO-OCCLUSIVE DISEASE Pulmonary hypertension and vaso-occlusive disease is the single most important risk factor in ASD as it renders a curable disease inoperable. Along with the oxygen saturation it is also a strong predictor of mortality. It occurs in 5–10% of patients, predominantly in the females usually after 20 years, although the rare cases have been reported in early childhood.5 There are many controversies about severe PAH and Eisenmenger syndrome in patients with ASD. Pathologically, PAH is characterized by predominantly There is a good chance of intimal disease in contrast to other spontaneous closure of atrial shunts. The severity is not directly septal defects detected in related to shunt size. Debate newborn period. continues about the cause of the pulmonary vaso-occlusive disease and which patients are at risk and at what age.

HEART FAILURE The presence and severity of the functional limitations among the 7

ECAB Clinical Update: Cardiology

patients with ASD increase with age. Heart failure is relatively uncommon in first 2–3 decades but becomes common after the age of 40 years. Though younger patients may have some dyspnea but are rarely seriously disabled, but it The incidence of cardiac worsens rapidly after 40 years. The arrhythmias in patients with incidence of heart failure is 17% atrial septal defect increases in 40–50 years’ age group, 40% in steeply with age. 51–60 years and almost 85–90% in those aged above 60 years. 6 The development of diseases like hypertension can also add to the problem.

ATRIAL ARRHYTHMIAS The arrhythmias are more common in patients with large left to right shunt. Cardiac arrhythmias of permanent nature, namely atrial fibrillation and atrial flutter are common. The incidence of atrial arrhythmias increases steeply with age among patients with ASDs. This results in precipitation and/or worsening of symptoms especially if there is associated myocardial dysfunction, especially in older patients as they may have associated cardiac diseases. Indeed, the incidence is 13% in patients above 40 and 53% in those above 60 years. The risk of thromboembolism will only further add to the overall poorer prognosis.

REPAIRED ASD After successful closure of ASD, especially at an younger age the over all outcomes are better. The correction of the defect at an older age may not protect the patient against atrial arrhythmias and further deterioration of pulmonary vascular disease.

PATENT FORAMEN OVALE In many series of strokes (cerebrovascular accident), patent foramen ovale (PFO) has been detected in varying percentages. The PFO is suggested as the route for embolus (paradoxical embolism). This has 8

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Desai, Koregol and Singh

resulted in an interest in this innocuous looking defect. If there is a risk it is unclear how to address this issue and at this stage, it is not necessary to look for this defect in routine clinical practice.

Mortality Certainly most patients do well in the first 2 decades. However, postponing a definite intervention for too long may be counterproductive. The life expectancy is greatly reduced from the third and fourth decade onwards.7 This seems to continue in the fifth and subsequent decades of life. The calculated mortality per annum is 2.6% in third and fourth decade, 4.4% in fifth decade, and 7.3% per annum for sixth decade onwards. Predominant causes of death include CHF, pulmonary thromboembolism and bronchopulmonary infections.2

ATRIOVENTRICULAR SEPTAL DEFECT The life history depends on morphologic and functional details of this malformation. The natural history of the patients with untreated partial AV canal defect without significant left AV valve regurgitation is similar to that with patients with large ASD. Patients with partial AV septal defect and moderate or severe left AV valve regurgitation have different natural history, and severe left atrial and pulmonary venous hypertension can occur. When the left to right shunt is large and associated with pulmonary hypertension it suggests poorer outcomes. Probably about 20% of such individuals are severely symptomatic in infancy and without surgical treatment, a large percentage may die Major causes of death in patients with patent foramen ovale: in the first decade of life. congestive heart failure, For patients with complete AV canal defect, there is no study or pulmonary thromboembolism and bronchopulmonary infections. database that records the history of these patients from birth and hence ideal delineation of the natural history is not possible. An important event about which we have data is development of severe pulmonary hypertension which occurs in 30% by 7–12 months and 9

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almost in 90% by 3–5 years. The mortality as estimated from case reports is high with 80% dying by 2 years and among the patients who are alive at 1 year, only 15% survive till fifth year.9 There is an inverse relationship between the age at diagnosis of ventricular septal defect and probability of its spontaneous closure.

NATURAL HISTORY OF VENTRICULAR SEPTAL DEFECT

Ventricular septal defect (VSD) is the second most common congenital heart defect after bicuspid aortic 1 valves, yet their true incidence is surprisingly unknown. VSDs constitute about 20% of all CHDs and incidence is 5–50/1000 live births. Similarly, their natural history including incidence of spontaneous closure, is uncertain and ranges from trivial to high. The natural history is dependent on the size of the defect. The natural history of VSD is complicated by endocarditis, congestive heart failure, development of significant aortic regurgitation (AR), right ventricular outflow tract obstruction, occurrence of arrhythmias, pulmonary vascular disease (Eisenmenger syndrome) and death.

Spontaneous Closure VSDs have a very high tendency to close, especially if they are small or moderate in size. Spontaneous closure may be complete by 1 year.10 However, some decrease in size and tend to close after varying length of period. An inverse relationship exists between the probability of closure and the age at the time of diagnosis. About 80% of large VSDs seen at the age of 1 month, eventually close spontaneously, as well as 60% of those seen at 3 months, 50% of those seen at 6 months and 25% of those seen at 12 months.11 Though the closure is rare after infancy, there are documented cases of closure even in third and fourth decade. Juxtaaortic (subaortic) and inlet VSDs are less likely to close.

PULMONARY VASCULAR DISEASE Patients with a large VSD run a higher risk of developing pulmonary hypertension which tends to worsen with age. The proportion of 10

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Desai, Koregol and Singh

patients with large VSD who have severely elevated pulmonary vascular resistance is directly related to age.12 Some infants do not exhibit the usual fall in pulmonary vascular resistance in the first few weeks of life while others do. It is those patients who do not exhibit fall in pulmonary vascular resistance, develop rapid increase in PVR and are destined to develop Eisenmenger syndrome.13,14 Some infants with large- and moderate-sized VSDs have normal or mildly elevated pulmonary vascular resistance, which remains same throughout the first decade of life. If VSD still remains large, more severe pulmonary vascular resistance may or may not develop as they age further. Infants with small VSDs will not develop pulmonary hypertension.

INFECTIVE ENDOCARDITIS Infective endocarditis (IE) is a rare complication in patients with VSD. The incidence is 0.15–0.3% per annum and is more common in smalland moderate-sized VSDs than large, non-restrictive VSDs.15 The prevalence is greater in males and persons over 20 years of age. Often they present with pulmonary symptoms due to embolization in pulmonary circulation. Prognosis of IE is good with appropriate antibiotic treatment and is poor when not treated.

Mortality The data from historical reports suggest that without the surgical treatment, the mortality for the infants with large VSD is 9–10% in first year Incidence of infective endocarditis in ventricular septal defects is of life, mostly attributable to heart higher in small- and failure. The heart failure occurs early moderate-sized defects than in in life, but usually at about 2–3 months large-sized defects. of age.16 Death may also occur from recurrent pulmonary infections. Death is more likely to occur in patients with large VSDs and associated co-morbidities. After the age of 1 year, few patients die of VSD until the second decade of life. By this time, most patients whose VSD has 11

ECAB Clinical Update: Cardiology

remained large have pulmonary vascular disease and ultimately die of complications of Eisenmenger syndrome mainly hemoptysis, polycythemia, cerebral abscess or infarction, and right-sided heart failure. Patent ductus arteriosus carries the highest life expectancy among the three most common left to right shunts.

In those with small VSDs, death is very rare and mostly results from bacterial endocarditis.

AORTIC REGURGITATION

Aortic valve insufficiency can occur in patients with sub-aortic and peri-membranous VSDs, more common in the former. Regurgitation is rarely present at birth but develops during the first decade of life, then gradually worsens, so that by the end of the second decade, it is usually severe. This complication occurs in about 10% of large- and moderate-sized VSDs. About 8% of patients with perimembranous VSDs and more than 30% of those with subaortic VSDs, develop some degree of aortic regurgitation.15 The degree of aortic regurgitation tend to increase on follow-up. It is due to prolapsing of right coronary cusp. As the regurgitation increases, the degree of shunt flow tend to decrease. This is due to reduction in the size of the defect by the prolapsed aortic cusp.

INFUNDIBULAR PULMONARY STENOSIS Five to ten percent of patients with VSD and non-restrictive shunt in infancy may develop subsequent infundibular pulmonary stenosis or right ventricular outflow tract obstruction secondary to myocardial hypertrophy, which can vary from mild to severe, which tend to protect the pulmonary vascular bed from the excess blood flow.17 When the right ventricular outflow tract obstruction becomes severe, right to left shunt occurs, resulting in a clinical picture similar to the tetrology of Fallot. Those who undergo this transformation are probably with a mild degree of anterior displacement of infundibular septum and its extensions.

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PATENT DUCTUS ARTERIOSUS It is difficult to describe the natural history of patent ductus arteriosus (PDA) as it became amenable to the surgical cure very early in the history of cardiovascular surgery and also the penicillin significantly reduced the other complication i.e., the infective endarteritis. The life expectancy of those with PDA is shortened but their lives are often too long to be covered by a doctor’s ordinary time in practice. The natural history of PDA depends largely on the size and magnitude of the shunt and the status of the pulmonary vasculature. Many patients with small ductus arteriosus never have signs of significant hemodynamic burden and, other than the risk of endarteritis, have a normal prognosis. Those patients with significant left heart volume overload, however, are at risk of congestive heart failure or irreversible pulmonary vascular disease, even if asymptomatic or minimally symptomatic during childhood. The natural history of PDA can be discussed under the headings of spontaneous closure, pulmonary vascular disease, congestive heart failure, infective endarteritis, aneurysm of ductus and mortality.

Spontaneous Closure Functional closure of the ductus often occurs within the few hours of the birth and anatomically, it is generally closed within 6 weeks. Throughout the first few years, some PDAs continue to close but about 1% are patent at the end of the first year. After infancy, the ductus may close at any age. The Functional closure of the ductus various reported rates of closure vary arteriosus occurs within between 0.3% and 0.9% per annum. first few hours of birth and Most of the data comes from the the anatomical closure generally elegant records of Brown, Benn, occurs within 6 weeks. Campbell and Cosh, which suggest an average incidence of 0.60% per annum after the infancy (see Table 1).

CONGESTIVE HEART FAILURE Children and adults with moderate to large patent ductus frequently 13

ECAB Clinical Update: Cardiology

develop symptoms of congestive heart failure due to pulmonary circulatory overload and left heart volume overload. If the ductus is large and offers minimal resistance to flow (nonrestrictive), the degree of shunting depends on the status of Incidence of endarteritis in patent the pulmonary vascular resistance. In ductus arteriosus has significantly many children with moderate or large decreased after usage of patent ductus, pulmonary vascular antibiotics became common. resistance remains modestly elevated, which limits the shunting sufficiently to lessen the physiological impact and permit survival and growth. Although patients with small to moderate ductus often remain asymptomatic during infancy and childhood, and some may never develop symptoms, those with significant chronic volume overload of the left heart may develop congestive heart failure in adulthood, starting in the third decade. In the adult, heart failure is frequently associated with atrial flutter or fibrillation.

PULMONARY HYPERTENSION The prevalence and type of the pulmonary vascular disease in patients with large patent ductus arteriosus is similar to those with large ventricular septal defect (which has already been discussed).19

ENDARTERITIS The early natural history studies before the era of routine surgical

Table 1. Spontaneous Closure of PDA Author

Number of patients Closing

Brown et al21 Benn et al

20

Campbell et al19 Cosh et al Total

22

2

Patient years

Percentage per annum

627

0.32

Total 63

2

46

398

0.50

5

168

546

0.9

4

61

669

0.60

11

292

1842

0.60

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Desai, Koregol and Singh

closure and use of antibiotics, when the incidence of infective arteritis was reported to be 1% per year. In fact, it was the major cause of mortality.

ANEURYSM OF DUCTUS ARTERIOSUS Aneurysm of the ductus arteriosus is an entity with a reported incidence as high as 8%. The true incidence is unclear because the definition of ductus arteriosus aneurysm is not precise and because many incidentally discovered ductus arteriosus aneurysms detected by fetal or neonatal echocardiography resolve spontaneously with ductal closure and thrombosis, without clinically apparent sequelae. Ductal aneurysm most commonly presents in infancy but has also been reported in adults and may develop after infective endarteritis, surgical closure, or transcatheter coil occlusion. In approximately one-fourth of patients, an underlying disorder such as Trisomy 21, Trisomy 13, Smith-Lemli-Opitz syndrome, type IV Ehlers-Danlos syndrome, or Marfan’s syndrome is present.

Mortality Speaking from the natural history point of view, meaning strictly without treatment, the mortality due to PDA is high in the first year of life. It falls sharply and exponentially from first week to first year. The reports of Hay and Campbell suggest a mortality of 30 ± 10%. Mortality is lower after second year onwards but increases with age and considerably reducing the life A clear understanding of natural expectancy. Most of the data in this history of the shunts helps in age group is derived from the followtaking management decisions. up of school children or for the hospital records which might give slightly higher than average rates of mortality. The risk of death from 2 years to 19 years is about 0.5% per annum (see Table 2), in third decade it is about 1% per annum and fourth decade onwards, data is scant but the estimated rate of mortality is 1.8% per annum (see Table 3).

15

367

0.27

Patient years

Mortality

16

0.43

470

2

47

Total

Campbell 5 in 504

2 in 65

3 in 110

Welti and Koerperich 23

0 in 105

0 in 70

No. of deaths

0 in 154

18

0.37

270

1

46

Benn20

0.57

348

1

61

Cosh22

1.0

3.1

2.7

0

0

0

Mortality rate per annum

Age 20–29 years

Cosh 22

Brown

21

Wilson and Lubschez24

Series

1

No. of deaths

Brown21

0.9

121

1

11

Welti 23

0.6

332

2

123

Campbell19

No. of deaths

8 in 439

4 in 149

2 in 143

2 in 95

0 in 52

—

0.49

1638

8

280

Total

1.8

2.7

1.4

2.2

0

—

Mortality rate per annum

Age over 30 years

Table 3. Mortality Rates due to PDA in Patients over 20 Years of Age

38

No. of patients

Wilson24

Table 2. Mortality Rates due to PDA in First Two Decades of Life

ECAB Clinical Update: Cardiology

Natural History of Left to Right Shunts



Desai, Koregol and Singh

The natural history of aorto-pulmonary window is similar to the comparable sized PDA. Though most of the physicians and surgeons in present times are unlikely to witness natural history of any of the conditions described above, it is essential for understanding the benefits of the treatment both surgical and medical and to be able to recognize the patients when they present late in the presence of disease.

REFERENCES 1.

Webb G, Gatzoulis MA. Atrial septal defects in the adult: recent progress and overview. Circulation 2006;114:1645–53.

2.

Campbell M. Natural history of atrial septal defect. British Heart Journal 1970;32:820–6.

3.

Fukazawa M, Fukushige J, Ueda K. Atrial septal defects in neonates with reference to spontaneous closure. Am Heart J 1988;116:123–7.

4.

Mody MR. Serial hemodynamic observations in secundum atrial septal defect with special reference to spontaneous closure. Am J Cardiol 1973;32:978–81.

5.

Besterman E. Atrial septal defect with pulmonary hypertension. Br Heart J 1961;23:587–98.

6.

Hamilton WT, Haffajee CI, Dalen JE, et al. Atrial septal defect secundum: clinical profile with physiologic correlates in children and adults. Cardiovasc Clin 1979;10:267–77.

7.

Perloff JK. Ostium secundum atrial septal defect—survival for 87 and 94 years. Am J Cardiol 1984;53:388–9.

8.

John Sutton MG, Tajik AJ, McGoon DC. Atrial septal defect in patients ages 60 years or older: operative results and long-term postoperative follow-up. Circulation 1981;64:402–9.

9.

Maloney JV. The surgical treatment of common atrioventricular canal. J Thorac Cardiovasc Surg 1962;43:84.

10. Hofman JI, et al. The natural history of ventricular septal defect in infancy. Am J Cardiol 1965;16:634.

17

ECAB Clinical Update: Cardiology

11. Collin J, Calder L, Rose V, et al. Ventricular septal defect: clinical haemodynamic changes in the first five years of life. Am Heart J 1972;84:695. 12. Bacterial endocarditis in patients with aortic stenosis, pulmonary stenosis, or ventricular septal defect. Circulation 1993;87 (2 Suppl):I121–6. 13. Auld PA, Johnson AL, McGregor M. Changes in the pulmonary vascular resistance in infants and children with left to right intracardiac shunts. Circulation 1963;27:257. 14. Lucas RV Jr, et al. The natural history of isolated ventricular septal defects: serial physiologic study. Circulation 1961;24:1372. 15. Saleeb SF, Solowiejczyk DE, Glickstein JS, et al. Frequency of development of aortic cuspal prolapse and aortic regurgitation in patients with subaortic ventricular septal defect diagnosed at 1.7:1 significant and suggest a large shunt. Ventricular septal defecto >2:1 Typically apical diastolic flow Patent ductus arteriosus o >2:1 murmurs and other features of large pulmonary blood flow accompany shunts of this magnitude. For ASD, shunt ratios in excess of 1.7:1 are considered important. Qp/Qs ratios are reliably obtained only through cardiac catheterization. It is important to understand that Qp/Qs ratios obtained by echo are very unreliable and can mislead. Today cardiac catheterization is not performed for a majority of patients with 55

Anatomic evaluation

56

Ventricular septal defect

Echocardiography is usually sufficient for infants. TEE may be required for the occasional older patient.

Atrial septal defect Echocardiography Primum, fossa (TTE and TEE) ovalis and sinus provides sufficient venosus) anatomic detail in almost all cases. Checklist for evaluation should include pulmonary veins and mitral valve.

Diagnosis

Indications for catheterization

Indication for intervention (surgery or catheter based)

Oxygen saturation 1. Suspected pulmonary Elective closure for all and PO2 levels, hypertension, to rule ASDs with evidence of RV volume overout coronary artery RV volume overload at load pattern on disease. preschool (5–6) years’ echo, flow direction 2. Rare patient with age if asymptomatic. across the ASD. relatively small ASD, to Closure can be done quantify Qp/Qs ratios earlier (if necessary, (>1.7:1 may merit during infancy) if closure). patient symptomatic. 3. Device closure of selected fossa ovalis defects. History: Failure to 1. Suspicion of elevation All large VSDs should thrive, frequent in PVR (threshold for ideally be closed respiratory infeccardiac catheterization electively between tions. in older children is often 3–6 months’ age and Physical examination: lower). earlier if there are Active precordium, 2. Device closure of symptoms. The apical flow rumble. selected muscular higher possibility of ECG: Q in lateral VSDs. spontaneous closure chest leads. in muscular VSDs Chest X-ray: Heart size may allow and lung vascularity. consideration for Echo: Flow directions closure at an older age.

Physiologic evaluation

Table 6. Evaluation and Decision Making in Congenital Heart Disease with Left to Right Shunts

ECAB Clinical Update: Cardiology

Echo often demonSimilar to VSD. In Just as in VSD; cath data strates all aspects presence of may be confusing in of the lesion with Trisomy 21, there sedated infants with considerable is relatively higher Trisomy 21 clarity PVR often worsened by upper airway obstruction. Echo is often History, physical 1. Suspicion of PVR elevasufficient for exam and ECG tion based on history anatomic inforclues are identical and physical examination. mation. TEE is as in VSD. Significant flow reversal not of additional Additional findings suggested by a lower O2 use. For older favoring operability saturation in lower limbs. patients with includes wide 2. Catheter closure (coil or limited windows, pulse pressure, device). cardiac cath may flow reversal in be required descending thoracic aorta, flow direction across PDA. Transient systolic flow reversal in young children may be compatible with operability, particularly in younger children and infants.

All large PDAs should be electively closed after 1–3 months’ age. All AP windows require early if not immediate consideration for closure as soon as the diagnosis is made. Moderate or small PDA can be electively closed after 1 year.

Small VSDs should be closed only if there is recurrent endocarditis or evidence of aortic valve prolapse. Complete AV canal should be addressed at an early age; often before 3 months’ age.



57

TTE: trans-thoracic echocardiography, TEE: trans-esophageal echocardiography, VSD: ventricular septal defect; ASD: atrial septal defects, Qp/Qs: ratio of pulmonary to systemic blood flows, PVR: pulmonary vascular resistance, RV: right ventricular; PDA: patent ductus arteriosus, AP: aortopulmonary.

PDA, aortopulmonary window

Complete atrioventricular canal defect

across the defect, LA and LV enlargement.

Surgery in CHD with L–R Shunts Shivaprakasha and Krishna Kumar

ECAB Clinical Update: Cardiology

congenital heart disease because of progressive refinements in echocardiography. Cardiac catheterization has important morbidity and cost and this is totally avoidable in most situations today. However, cardiac catheterization is clearly indicated in specific situations. The indications for cardiac catheterization Ventricular septal defect closure have been spelt out in the Table 6. should never be delayed because of poor nutritional status. The Effect of Co-morbidities The impact of associated malnutrition and lung infection on outcomes after VSD closure has been extensively studied at our institution.13–16 We firmly believe VSD closure should not be delayed because of poor nutritional status.13 In presence of pneumonia, delay beyond what is required for initial control of sepsis and lung infection is also not perhaps acceptable.13,16 An aggressive policy to close the defects is usually quite rewarding as it allows early elimination of the shunt and avoids unnecessary prolongation of intensive care.16

SURGICAL OPERATIONS FOR LEFT TO RIGHT SHUNTS The surgical interventions are broadly categorized into surgical procedures that utilize the cardiopulmonary bypass (CPB) or not. Essentially the non-bypass procedures are limited to corrective procedure like interruption of the ductus arteriosus and a palliative procedure like pulmonary artery banding as an initial stage procedure.

Pulmonary Artery Banding The palliative closed heart operation, pulmonary artery banding that essentially involves placing a flow restricting band to reduce the diameter of the main pulmonary artery. This operation has become restricted to highly complex substrates of VSD such as Swiss-cheese type multiple VSDs,17 VSD with coarctation of aorta or multiple defects with significant comorbidity that does not allow openheart operation.16

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Technique This operation is performed through either a left anterior thoracotomy, left posterior thoracotomy when associated arch lesions like coarctation need to be simultaneously addressed or median sternotomy. The main pulmonary artery is encircled with a Teflon tape and width of the band is determined by following Trusler’s rule: PAB width = 20 + body weight Additionally other parameters such as saturation, measurement of pulmonary artery pressures distal to the band, EtCO2 (end tidal carbon dioxide) are also closely monitored. A saturation of 80 ± 5%, with mean pulmonary artery pressures 1/3 of mean systemic pressures are considered generally satisfactory.18

Patent Ductus Arteriosus Most patent ducts can now be addressed in the catheterization laboratory by means of devices or coils.19,20 However, very small infants with large ducts, preterm infants and occasional infants with large window like ducts can only be dealt with by the surgeon. The ductus is interrupted employing various types of incision that are lateral, postero-lateral, muscle sparing thoracotomy incisions. The ductus in premature infant is often closed in the neonatal intensive care unit. However, those ducts that result in severe cardiac failure are ideally operated in operating rooms. Transporting the baby from neonatal nursery to the operating suite is a critical step in the smooth conduct of this operation. Usually the ductus is Most of the patent ductus interrupted under hypotensive arteriosus lesions can be anesthesia by double ligation and triple managed by cardiac ligation with a transfixation stitch in catheterization and coil occlusion. infants and older children. Some perform more radical but superior division and suture technique thereby eliminating the chance of residual duct. This option of dividing the ductus remains an individual surgeon’s preference rather than evidence based.

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ECAB Clinical Update: Cardiology

Recently videoscopic interruption of the ductus has gained prominence in selected babies as it is considered less invasive and more aesthetic. Indication of surgical closure of atrial septal defect:  Defects with deficient/absent margins 



Large defects in adults (>35–40 mm) Relatively large defects in young children

Ductal aneurysms and calcified ducts are approached through midline and they are closed from both sides— aortic and pulmonary. The operation for these complex situations requires assistance of bypass and occasionally cardioplegia and circulatory arrest as well.

Atrial Septal Defects While catheter-based management of fossa-ovalis type of ASD is gaining increasing acceptance, there is a definite role for surgery. Defects with deficient or absent margins, very large defects (>35– 40 mm in adults), young children with relatively large defects are all candidates for surgical closure.21 The mini-sternotomy or posterior thoracotomy approach allows cosmetically acceptable scars for patients with ASD.22 Atrial septal defects in the fossa-ovalis region are closed either directly or with patch materials. The decision to close either directly or with patch material is dependant upon the size, shape and location of the defect (Fig. 3). Certain elliptical secundum can be closed directly. The larger defects with deficient rims on any side are closed with a patch of pericardium. Sinus venosus and primum defects are not amenable to catheter-based treatment and are always closed with a patch. A cribiform septum that has a sieve-like septum is always addressed by excising the completely defective septum and then closing the whole defect with patch. Sinus venosus defects are slightly more complex problems as they are usually accompanied by a partial anomalous pulmonary venous drainage of one or two right superior pulmonary veins to the superior vena cava (SVC). The problem is further compounded by the common association of bilateral SVC with a relatively small right SVC and a 60

Surgery in CHD with L–R Shunts



Shivaprakasha and Krishna Kumar

Fossa ovalis OP SVC

CS SV

RV

FO

IVC

Figure 3. Anatomic classification of atrial septal defects. The free wall of the right atrium has been removed to expose the septum. CS: coronary sinus, IVC: inferior vena cava, OP: ostium primum defect, RV: right ventricle, SV: sinus venosus defect, SVC: superior vena cava.

larger left SVC that drains via the coronary sinus (Fig. 4). Since the defect lies in close proximity to the sino-atrial (SA) node also, there have been various techniques to close the defect while avoiding injury to the SA node. The currently preferred techniques are: 

Conventional technique wherein the defect is exposed by a reverse ‘L’ incision over the right atrium starting from the base of the right atrial appendage towards the lateral aspect of the superior vena cava. This allows the morphology of the defect to be properly delineated. A patch is sutured into position in such a 61

ECAB Clinical Update: Cardiology

Figure 4. Operative photograph from a patient with sinus venosus atrial septal defect. This patient has a left superior vena cava draining into the coronary sinus.

way that it reroutes the anomalous pulmonary vein(s) to the left atrium while closing the defect. The potential narrowing of SVC is addressed by closing the incision over the lateral caval part with a pericardial patch thereby augmenting the lumen of the SVC. 

Transecting the SVC just downstream to the uppermost pulmonary venous drainage and then anastomosing it to the right atrial appendage. This routes the SVC to right atrium. Closure of sinus venosus defect automatically reroutes the anomalous pulmonary veins to the left atrium. This is considered to be a radical operation for a simple defect.



The lateral-caval approach: The SVC in its lateral aspect is opened just anterior to the pulmonary veins and then a properly fashioned patch of pericardium is sandwiched between anomalous pulmonary veins and the ASD on one side and the SVC lumen on the other side. This results in effective, satisfactory rerouting of pulmonary veins while ensuring an adequate lumen of SVC. This

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Shivaprakasha and Krishna Kumar

is a much simplified approach without the need to enlarge the SVC (Figs. 5A and 5B). 

Butterfly approach: A patch is used to close the sinus venosus defect and the patch is turned back and sutured to the edges of the incision thereby restoring the lumen of the SVC. Though the technique gives satisfactory result, it takes longer to operate with this technique.

All these techniques have been successfully applied employing cosmetically appealing limited posterior thoracotomy technique as well.22 All techniques have given satisfactory short- and long-term results for the repair of sinus venosus defects. Incision over the vena cava

View of the defect

B

A

C

PV

patch

D

Figure 5. Operative steps in repairing a sinus venosus defect using the “sandwich” technique. A: A longitudinal incision is made on the anterior aspect of the superior vena cava (SVC); B: The atrial septal defect (ASD) is exposed along with the anomalous right pulmonary veins; C: A pericardial patch is sutures to the leftward edge of the defect; D: The edges of the incision are sutured together while suturing the medial edge of the defect. This allows the pulmonary veins to be routed to the left atrium. 63

ECAB Clinical Update: Cardiology

Primum defects are always closed with a pericardial patch. During this surgery, it is very critical to avoid placing the stitches within the Koch’s triangle to avoid injury to the conduction system. The various techniques to achieve this are While performing the pericardial described in the management of atriopatch repair of the septum ventricular (AV) canals. primum defect, care should be taken to avoid placing stitches in Partial Anomalous and the Koch’s triangle to avoid Hemianomalous Pulmonary injury to conduction channels. Venous Connections These lesions present in different ways. The commonest form wherein the right-sided pulmonary veins are draining into right atrium anterior to the atrial septum. They are repaired by excising the atrial septum in the fossa ovalis region (sometimes this step is unnecessary, if there is already a large fossa ovalis defect) and then suturing a patch anterior to pulmonary veins. Quite often, the left-sided pulmonary veins drain anomalously into the innominate vein. Either a lateral thoracotomy without CPB or midline approach with CPB is employed. In both the techniques, the pulmonary vein is transected at its drainage into innominate vein. The end towards innominate vein is sutured off. The other end is cut back to create a patulous opening. The left atrial appendage is amputated at its tip or else a trap door is created by opening the left atrial appendage in such a way that the appendage tissue forms the anterior hood. Both ends are anastomosed to each other. The hood of the left atrial appendage forms the anterior covering of the anastomosis. It is important to snare of the LPA during this procedure to prevent left pulmonary edema.

Ventricular Septal Defects Ventricular septal defects (VSDs) are closed employing extra-corporeal circulation. Generally they are closed with prosthetic material such as poly-tetra-fluoro-ethylene (PTFE) or Dacron. Alternatives include bovine pericardium or the patients own (autologous) pericardium. All

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materials have proven their safety and durability and are by and large resistant to infection. However, in presence of underlying sepsis or severe pneumonia, autologous pericardium may be preferred by many surgeons. Smaller defects located in the muscular portion of the septum can be considered for direct closure. A defect located in the subpulmonary position is usually closed with a patch to avoid distorting the integrity of aortic valve cusp. Most of the defects are closed with a continuous suture technique and begins by staring at postero-inferior aspect of the defect and continuing anti-clockwise. Trans-atrial route is the commonly preferred approach as most of the membranous defects and muscular defects situated in the upper portion of the septum close to the tricuspid valve and in the RV apex can be accessed with ease from the right atrium and across the tricuspid valve. The defects that are situated in the anterior muscular portion, in the infundibular apex (the septum from the RV infundibulam to the apex of the right ventricle adjoining the inter-ventricular septum) are closed by appropriate ventriculotomy.23 Very rarely aortic route is employed wherein the defects are approached through the aortic valve. Occasionally, the videoscope has been inserted across the aortic valve into the LV cavity to visualize the defects and then close them. However, it is emphasized again that these extraordinary circumstances are rare and are not universally followed. It is useful to have a roadmap Careful 2D/3D provided for the location of the echocardiography should be used muscular defects. Careful crossto define ventricular septal defect sectional (two-dimensional) in order to plan the surgical echocardiography or more recently, approach for its closure. three-dimensional echocardiography allows precise definition of the VSD (Fig. 6). This allows the surgeon to plan the approach to the VSD.17

Atrio-ventricular Canal The complexity of the repair varies depending upon the subtypes of defects as they represent a spectrum of lesions. At one end, simpler 65

ECAB Clinical Update: Cardiology

Figure 6. Parasternal short-axis sweep in a patient with a large midmuscular VSD. Frame 1 reveals the intact inlet septum at the levels of the belly of the MV and TV. Frame 2 cuts through the trabecular septum at the level of M moderator band (MB) insertion site. Here, a hypertrophied septal band may render the margins of a VSD irregular. Frame 3 illustrates the most apical cut. The VSD is not visualized. The numbered arrows in the drawing (Frame 4) indicate the planes of section for the corresponding frames, and the shaded area represents the VSD. LV: left ventricle; MB: moderator band; MV: mitral valve; RV: right ventricle; TV: tricuspid valve; VSD: ventricular septal defect.

forms like primum ASD that are usually associated with a cleft mitral valve are present while at the other end are complex types of complete atrio-ventricular canal defects with abnormal attachments of the support apparatus of the common anterior leaflet. 66

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Shivaprakasha and Krishna Kumar

Partial AV canal repair includes closure of cleft in the left atrioventricular valve and closure of primum ASD. The cleft in the leaflet is closed with direct interrupted sutures. Rarely the cleft will be actually a big defect in the center of the anterior leaflet of the left AV valve and then it has to be repaired with a small patch of pericardium. This is in order to avoid the distortion of the leaflet and the annulus that might result due to the direct suturing of the cleft. Primum ASD is addressed in the same fashion as was described earlier. Complete endocardial AV canals are usually repaired in the first 3 months of life. Usually the correction entails: 1.

Closure of inlet type of ventricular septal defect: This is generally achieved with a comma-shaped patch of Gore-Tex or Dacron. Either interrupted pledgeted sutures or continuous sutures technique is employed. The VSD sometimes excavates deeply into the infundibular portion when it is associated with outflow tract obstruction and then proper fashioning of the patch is essential as it may result in either sub-aortic obstruction or else might result in AV valve incompetence. Precise size and shape of the patch is of paramount importance in achieving optimal repair in these subsets. The stitches in the postero-inferior aspect of the defect should be taken away from the crest of the IVS so as to avoid injury to the bundle of His. There have been few reports that advocate employing a single patch of pericardium or closing the defect by directly approximating the crest of the septum to the underside of the common leaflet. Though the technique is reportedly good, it has not found universal acceptance.

2.

Repair of the left AV valve: The common anterior leaflet can vary in its anatomy depending upon the individual subtypes of AV canals. The variation consists of common leaflet with no commissure in the center of the common anterior leaflet to a clear-cut commissure dividing the leaflet into right and left component. Approximating the common anterior and common posterior leaflet in the center 67

ECAB Clinical Update: Cardiology

creates the neo-crux. Care is taken to keep adequate leaflet tissue on the left side in case there is a need to divide the common anterior leaflet into two portions. Optimal outcomes of these repairs are entirely governed by the control of the regurgitation achieved without compromising the diameter of the left AV valve for the body surface areas. Occasionally, annuloplasty stitches are necessary in order to control the regurgitation. These are placed at commissural points so as to reduce the circumference of the annulus and thereby increasing the degree of coaptation of the leaflets. 3.

Closure of the primum ASD: This is always done by employing a pretreated pericardial patch (to prevent the shrinkage of the pericardium). The important point during this step of operation is to avoid the injury to the conduction system. Some prefer to close the defect by incorporating the coronary sinus so that the stitches are taken outside the Koch’s triangle. This usually results in some degree of sub-clinical desaturation that is of no clinical consequence. Others prefer to close the defect by keeping close to either coronary sinus or the left AV valve while taking bites to place the patch. Either technique has resulted in excellent outcomes.

4.

Repair of the right AV valve: It is not mandatory to be aggressive to repair the right AV sided valve. However, it is important to inspect the valve and see the quantum of regurgitation. Occasionally some reconstruction is necessary to control the regurgitation. If the commisure between the right and left component is total then the right component is attached to the right side of the VSD patch and then is sutured to the common posterior left so that a neo-septal leaflet is created.

Postoperative Features 

Pulmonary arterial lines are routinely placed following repair of complete AV canals. These are usually removed 2 days after monitoring is discontinued. 68

Surgery in CHD with L–R Shunts



Shivaprakasha and Krishna Kumar



AV canals are known to have pulmonary vascular reactivity and their pulmonary pressures are hypersensitive to stimulus like fever, hypoxemia and hypercarbia as a result of any cause. The PA pressures might reach systemic/supra-systemic levels resulting in cardiac decompensation (PH crisis). Prompt diagnosis and administration of appropriate therapy is of paramount importance.



Varying degrees of heart block including the complete heart block are more common after AV canal surgery in view of the proximity of the conduction system to the operative area. Hence, both atrial and ventricular temporary pacing wires are placed in order to address this problem in the early postoperative period. However, the modern practice of congenital heart surgery encounters CHB in