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(BQ) Part 1 book Pediatric cardiology - The essential pocket guide presents the following contents: Tools to diagnose cardiac conditions in children, environmental and genetic conditions associated with heart disease in children, classification and physiology of congenital heart disease in children, anomalies with a left-to-right shunt in children,...
Pediatric Cardiology The Essential Pocket Guide Pediatric Cardiology The Essential Pocket Guide THIRD EDITION Walter H Johnson, Jr., MD Professor of Pediatrics Department of Pediatrics Division of Pediatric Cardiology University of Alabama at Birmingham Birmingham, AL, USA James H Moller, MD Professor Emeritus of Pediatrics Adjunct Professor of Medicine University of Minnesota Medical School Minneapolis, MN, USA This edition first published 2014 © 2014 by John Wiley & Sons, Ltd © 2008 by Blackwell Publishing Ltd Registered office: John Wiley & Sons, Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK Editorial offices: 9600 Garsington Road, Oxford, OX4 2DQ, UK The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK 111 River Street, Hoboken, NJ 07030-5774, USA For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at www.wiley.com/wiley-blackwell The right of the author to be identified as the author of this work has been asserted in accordance with the UK Copyright, Designs and Patents Act 1988 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, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher Designations used by companies to distinguish their products are often claimed as trademarks All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners The publisher is not associated with any product or vendor mentioned in this book It is sold on the understanding that the publisher is not engaged in rendering professional services If professional advice or other expert assistance is required, the services of a competent professional should be sought The contents of this work are intended to further general scientific research, understanding, and discussion only and are not intended and should not be relied upon as recommending or promoting a specific method, diagnosis, or treatment by health science practitioners for any particular patient The publisher and the author make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of fitness for a particular purpose In view of ongoing research, equipment modifications, changes in governmental regulations, and the constant flow of information relating to the use of medicines, equipment, and devices, the reader is urged to review and evaluate the information provided in the package insert or instructions for each medicine, equipment, or device for, among other things, any changes in the instructions or indication of usage and for added warnings and precautions Readers should consult with a specialist where appropriate The fact that an organization or Website is referred to in this work as a citation and/or a potential source of further information does not mean that the author or the publisher endorses the information the organization or Website may provide or recommendations it may make Further, readers should be aware that Internet Websites listed in this work may have changed or disappeared between when this work was written and when it is read No warranty may be created or extended by any promotional statements for this work Neither the publisher nor the author shall be liable for any damages arising herefrom Library of Congress Cataloging-in-Publication Data Johnson, Walter H., Jr., author Pediatric cardiology : the essential pocket guide / Walter H Johnson Jr., James H Moller – Third edition p ; cm Includes bibliographical references and index ISBN 978-1-118-50340-9 (pbk.) I Moller, James H., 1933– author II Title [DNLM: Heart Diseases–Handbooks Child WS 39] RJ421 618.92′ 12–dc23 2013043842 A catalogue record for this book is available from the British Library Wiley also publishes its books in a variety of electronic formats Some content that appears in print may not be available in electronic books Cover image: courtesy of Robb L Romp, M.D Cover design by Andy Meaden Set in 8/10pt Frutiger Light by Laserwords Private Limited, Chennai, India 2014 Contents Preface, vii Tools to diagnose cardiac conditions in children, Environmental and genetic conditions associated with heart disease in children, 73 Classification and physiology of congenital heart disease in children, 86 Anomalies with a left-to-right shunt in children, 95 Conditions obstructing blood flow in children, 148 Congenital heart disease with a right-to-left shunt in children, 186 Unusual forms of congenital heart disease in children, 233 Unique cardiac conditions in newborn infants, 245 The cardiac conditions acquired during childhood, 259 10 Abnormalities of heart rate and conduction in children, 291 11 Congestive heart failure in infants and children, 315 12 A healthy lifestyle and preventing heart disease in children, 329 Additional reading, 373 Index, 375 v Preface Since the first printing of this text 50 years ago, pediatric cardiac catheterization, echocardiography, and magnetic resonance imaging have developed and less emphasis has been placed on the more traditional methods of evaluating a cardiac patient Most practitioners, however, not have access to these refined diagnostic techniques or the training to apply them To evaluate a patient with a finding that could suggest a cardiac issue, a practitioner therefore relies upon either the combination of physical examination, electrocardiogram, and chest X-ray, or referral to a cardiac diagnostic center This book formulates guidelines by which a practitioner, medical student, or house officer can approach the diagnostic problem presented by an infant or child with a cardiac finding Through proper assessment and integration of the history, physical examination, electrocardiogram, and chest X-ray, the type of problem can be diagnosed correctly in many patients, and the severity and hemodynamics correctly estimated Even though a patient may ultimately require referral to a cardiac center, the practitioner will appreciate and understand better the specific type of specialized diagnostic studies performed, and the approach, timing, and results of operation or management This book helps select patients for referral and offers guidelines for timing of referrals The book has 12 chapters: Chapter (Tools to diagnose cardiac conditions in children) includes sections on history, physical examination, electrocardiography, and chest radiography, and discusses functional murmurs A brief overview of special procedures, such as echocardiography and cardiac catheterization, is included Chapter (Environmental and genetic conditions associated with heart disease in children) presents syndromes, genetic disorders, and maternal conditions commonly associated with congenital heart disease Chapters to are “Classification and physiology of congenital heart disease in children,” “Anomalies with a left-to-right shunt in children” (acyanotic and with increased pulmonary blood flow), “Conditions obstructing blood flow in children” (acyanotic and with normal blood flow), “Congenital heart disease with a rightto-left shunt in children” (cyanosis with increased or decreased pulmonary blood flow), and “Unusual forms of congenital heart disease in children.” This set of chapters discusses specific congenital cardiac malformations The hemodynamics of the malformations are presented as a basis for understanding the physical vii viii Preface findings, electrocardiogram, and chest radiographs Emphasis is placed on features that permit differential diagnosis Chapter (Unique cardiac conditions in newborn infants) describes the cardiac malformations leading to symptoms in the neonatal period and in the transition from the fetal to the adult circulation Chapter (The cardiac conditions acquired during childhood) includes cardiac problems, such as Kawasaki disease, rheumatic fever, and the cardiac manifestations of systemic diseases which affect children Chapter 10 (Abnormalities of heart rate and conduction in children) presents the practical basics of diagnosis and management of rhythm disorders in children Chapter 11 (Congestive heart failure in infants and children) considers the pathophysiology and management of cardiac failure in children Medical and surgical (including transplantation) treatments are discussed Chapter 12 (A healthy lifestyle and preventing heart disease in children) discusses preventive issues for children with a normal heart (the vast majority), including smoking, hypertension, lipids, exercise, and other risk factors for cardiovascular disease that become manifest in adulthood Prevention and health maintenance issues particular to children with heart disease are also discussed This book is not a substitute for the many excellent and encyclopedic texts on pediatric cardiology, or for the expanding number of electronic resources The references sections accompanying some chapters and the additional reading section at the end of the book include both traditional and online resources chosen to be of greatest value to readers Certain generalizations are made In pediatric cardiology, as in all fields, exceptions occur Therefore, not all instances of cardiac abnormality will be correctly diagnosed on the basis of the criteria set forth here Conditions obstructing blood flow in children 171 The systolic pressure is elevated in the ascending aorta proximal to the obstruction; therefore, the coronary arteries are subjected to this elevated pressure The elevation can lead to tortuosity of the coronary arteries and to premature atherosclerosis The coronary artery ostia may be narrowed by the same obstructive process operating in the aorta and other large vessels and has a poor prognosis Two factors have been implicated in the etiology of this condition The first is Williams syndrome, in which a defect in the elastin gene is present The second is familial supravalvar aortic stenosis, which occurs in patients who not have Williams syndrome; they probably carry a mutated elastin gene (see Chapter 2) History Most patients are asymptomatic; cardiac disease is identified by either the presence of a murmur or the facial characteristics of Williams syndrome Congestive cardiac failure or growth retardation is rare, as in other forms of aortic stenosis, but sudden death can occur The risk might even be higher because of acquired abnormalities of the coronary arteries Physical examination The general physical characteristics of the child, particularly the facies, suggest the diagnosis of supravalvar aortic stenosis (see Chapter 2) However, many children appear normal Careful blood pressure recording in both arms and legs can lead to suspicion of supravalvar aortic stenosis if a blood pressure discrepancy of 20 mmHg or more is found between the arms (Coanda effect) This effect is related to either a narrowing of a subclavian artery or the pressure effect of the jet from the supravalvar aortic stenosis directed into the right subclavian artery In the latter circumstance, the blood pressure is higher in the right arm An aortic systolic ejection murmur is the prominent cardiac finding and, in contrast to valvar stenosis, is located maximally beneath the right clavicle, not along the left sternal border A systolic ejection click is not present because poststenotic dilation does not occur Diastole is silent, as valvar regurgitation does not occur Electrocardiogram The electrocardiogram usually shows features similar to those of valvar aortic stenosis, including left ventricular hypertrophy Some patients, for unknown reasons, show an rSr′ pattern in lead V1 and an Rs in lead V6 , without criteria of left ventricular hypertrophy ST-segment and T-wave changes may be present, reflecting myocardial ischemia that is possibly accentuated by coronary arterial abnormalities 172 Pediatric cardiology Chest X-ray The cardiac size is normal, with the absence of poststenotic dilation Natural history The narrowing in affected arteries may progress The major change over the course of this disease is the development of myocardial ischemia and fibrosis and its consequences, although findings of right heart hypertension predominate in peripheral pulmonary artery stenosis In following the patient, attention must be directed to the history of syncope or chest pain and to electrocardiographic changes in the ST segment and T waves Echocardiogram Cross-sectional views of the ascending aorta parallel to its long axis show discrete and often severe narrowing at the sinotubular junction and, at times, more diffuse narrowing into the distal ascending aorta Unlike valvar aortic stenosis, flow acceleration and turbulence begin at the supravalvar narrowing The gradient is estimated using spectral Doppler Associated lesions, such as branch pulmonary artery hypoplasia and stenosis, are readily detectable by cross-sectional echo; the presence of tricuspid and pulmonary valve regurgitation allows the estimation of right-sided cardiac pressures Cardiac catheterization The oxygen data are normal The diagnosis is established by measuring a systolic pressure difference within the ascending aorta (Figure 5.6c) and/or the pulmonary arteries Angiography demonstrates the anatomic details of the obstruction and, more importantly, identifies associated lesions – involvement of coronary, brachiocephalic, and peripheral pulmonary arteries – which is usually difficult by echocardiography Because a greater risk of coronary artery compromise exists, contrast injection into individual coronary arteries is usually avoided in favor of aortography Operative considerations Operative relief of the obstruction may be indicated for a lesser gradient, 30–40 mmHg, compared with aortic valvar stenosis, or if symptoms related to myocardial ischemia are present A longitudinal incision is made across the stenotic area, which is widened by placement of a diamond-shaped patch During the operation, the coronary ostia are inspected, but rarely is coronary arterial bypass indicated The operative risk for supravalvar aortic stenosis is higher than for valvar aortic stenosis Over the long term, reobstruction can occur because of progressive medial thickening of affected vessels Conditions obstructing blood flow in children 173 Summary Supravalvar aortic stenosis differs from valvar aortic stenosis since findings of poststenotic dilation are absent The lesion can progress and may involve multiple arteries Characteristic facies and abnormal chromosome probe are seen in Williams syndrome, which occurs sporadically, whereas other patients appear normal and have a normal chromosome probe but usually have multiple family members who are affected Relief of the obstruction in the ascending aorta can be accomplished by surgical widening of the narrowing with a patch P U L M O N A RY S T E N O S I S Pulmonary stenosis (Figure 5.7) occurs at three sites in the outflow area of the right ventricle: below the pulmonary valve (infundibular), at the level of the valve (valvar), or above the valve (supravalvar) Infundibular pulmonary stenosis rarely Figure 5.7 Valvar pulmonary stenosis Balloon dilation via catheter 174 Pediatric cardiology occurs as an isolated lesion Supravalvar stenosis or stenosis of the individual pulmonary arteries is uncommon after early infancy In most patients, obstruction occurs at the level of the pulmonary valve Regardless of the anatomic type of stenosis, the results are similar Blood flow through the stenotic area is turbulent and leads to a murmur The other major effect is an increase in right ventricular systolic pressure This effect is illustrated by the equation for calculating the area of the stenotic pulmonary valve orifice: PVA = PVF , √ K RV − PA where PVA is pulmonary valve area (area of stenotic orifice; cm2 ), PVF is pulmonary valve flow (blood flow occurring during the systolic ejection period; mL/s), RV is mean right ventricular pressure during ejection (mmHg), PA is mean pulmonary artery pressure during ejection (mmHg), and K is a constant Because of the restricted orifice, the level of right ventricular systolic pressure increases to maintain a normal cardiac output With the elevation of right ventricular systolic pressure, right ventricular hypertrophy develops, the degree of which parallels the level of pressure elevation With significant hypertrophy, right ventricular compliance is reduced, elevating right atrial pressure and causing right atrial enlargement Because of the right atrial changes, the foramen ovale may be stretched open, leading to a right-to-left shunt at the atrial level Right ventricular compliance may be reduced by myocardial fibrosis, secondary to the inability to meet augmented myocardial oxygen requirements A second complication of right ventricular hypertrophy is the development of infundibular stenosis that may become significant enough to pose a secondary area of obstruction The clinical and laboratory manifestations of right ventricular hypertrophy serve as indicators of the severity of the pulmonary stenosis Valvar pulmonary stenosis In the usual form of pulmonary stenosis, the valve cusps are fused, and the valve appears domed in systole A small central orifice and poststenotic dilation are found History No gender predominance in pulmonary stenosis exists Most patients are asymptomatic during childhood, but those with more severe degrees of pulmonary stenosis complain of fatigue on exercise The murmur of pulmonary stenosis is frequently heard in the neonatal period; critical pulmonary stenosis may present Conditions obstructing blood flow in children 175 with cyanosis Rarely, older patients may present with cyanosis and cardiac failure This combination of cyanosis and failure in pulmonary stenosis with intact ventricular septum usually occurs early in the first year of life, although it may occur at any age, and indicates severe stenosis and decompensation of the right ventricle Physical examination Most children appear normal, although cyanosis and clubbing exist in the few with right-to-left atrial shunt Usually, the cardiac apex is not displaced Often, a systolic thrill is present below the left clavicle and upper left sternal border and, occasionally, in the suprasternal notch A systolic ejection murmur, heard along the upper left sternal border and below the clavicle, transmits to the left upper back Usually, the murmurs are loud (grade 4/6) because the volume of flow across the valve is normal, but in patients with severe stenosis, particularly with cyanosis or cardiac failure, the murmur is softer because of reduced cardiac output The quality and characteristics of the second heart sound give an indication of the severity of the stenosis In severe stenosis, the pulmonary valve closure sound is delayed and soft (i.e it can be so soft that the second heart sound seems single) If a pulmonary systolic ejection click is present, it indicates pulmonary artery poststenotic dilation This finding is present in mild to moderate pulmonary stenosis, but it may be absent in severe pulmonary stenosis Electrocardiogram The electrocardiogram (Figure 5.8) is useful in estimating the severity of the pulmonary stenosis In mild pulmonary stenosis, the electrocardiogram may appear normal With more severe degrees of stenosis, right-axis deviation and right ventricular hypertrophy are found, with a tall R wave in lead V1 and a prominent S wave in lead V6 The height of the R wave roughly correlates with the level of right ventricular systolic pressure Right atrial enlargement commonly occurs, reflecting elevated right ventricular filling pressure In patients with severe stenosis, a pattern of right ventricular strain develops, manifested by ST-segment depression and deep inversion of T waves in the right precordial leads Inverted T waves in leads V1 –V4 not indicate strain in and of themselves because this pattern is normal in younger children Chest X-ray Usually, cardiac size is normal because the right heart volume is normal Cardiac enlargement is found with congestive cardiac failure or cyanosis because of the increased volume of the right heart chambers Except in patients with cyanosis, 176 Pediatric cardiology Figure 5.8 Electrocardiogram in pulmonary stenosis Tall R wave in V1 and right-axis deviation indicate right ventricular hypertrophy Conditions obstructing blood flow in children 177 Figure 5.9 Chest X-ray in pulmonary stenosis Normal-sized heart and pulmonary vasculature Poststenotic dilation of pulmonary artery the pulmonary vascularity appears normal, not decreased, because patients with pulmonary stenosis have normal systemic output and a normal quantity of blood passes through the pulmonary valve A distinctive feature of pulmonary valvar stenosis is poststenotic dilation of the pulmonary trunk and left pulmonary artery (Figure 5.9) This appears as a prominent bulge along the upper left cardiac border In patients with severe stenosis, this finding can be absent Summary of clinical findings The systolic ejection murmur indicates the turbulence of flow through the stenotic pulmonary valve Poststenotic dilation is indicated by the pulmonary systolic ejection click and the roentgenographic findings of an enlarged pulmonary trunk The electrocardiogram is the best indicator of the degree of right ventricular hypertrophy Right atrial enlargement, cyanosis, and congestive cardiac failure are indicators of altered right ventricular compliance resulting from severe right ventricular hypertrophy and/or fibrosis 178 Pediatric cardiology Natural history The orifice of the stenotic pulmonary valve increases as a child grows, meaning that the degree of obstruction usually does not increase with age The deterioration of the clinical status in some patients results from altered right ventricular myocardial performance related to fibrosis This complication occurs in infancy and in adulthood, but rarely in the mid-childhood years Occasionally, an infant or toddler has progression of infundibular stenosis without apparent change in the degree of valvar stenosis Echocardiography Cross-sectional echocardiography shows thickened and doming pulmonary valve leaflets Poststenotic dilation of the main pulmonary artery and ductus “diverticulum” can be dramatic Doppler recording reveals turbulent high-velocity flow through the pulmonary valve; the maximum velocity allows the estimation of the pressure gradient between the right ventricle and the pulmonary artery Right ventricular hypertrophy may occur, but quantitation is more difficult than in left ventricular hypertrophy, because of both right ventricular geometry and opposition between the right ventricular wall with the chest wall Differentiation of the boundary between the two structures is problematic Hypertrophy of the infundibulum, the tubular right ventricular outflow tract, can become severe and is easily demonstrated by cross-sectional echocardiography as the muscular walls squeeze the pathway virtually closed by the end of each systole Cardiac catheterization Oximetry data are normal except in an occasional patient with a right-to-left shunt at the atrial level The right ventricular systolic pressure is elevated, whereas pulmonary arterial pressure is normal or low Both pressure and cardiac output data are needed to assess the severity of the stenosis This is done by calculating the pulmonary valve area Right ventricular angiography outlines the details of the pulmonary valve and associated infundibular narrowing Balloon dilation is the procedure of choice to reduce the gradient Any patient with dome-shaped pulmonary valvar stenosis and a right ventricular-to-pulmonary artery systolic pressure gradient greater than 35 mmHg should undergo consideration for balloon valvotomy This low-risk procedure almost always results in a favorable outcome and reduces right ventricular systolic pressure to normal or near normal Even though pulmonary valvar regurgitation regularly results from valvuloplasty, it is well tolerated because the pulmonary arterial pressure is low In patients with a significant infundibular component, this procedure may not produce an immediate fall in right ventricular pressure; the infundibular stenosis usually resolves over several weeks Conditions obstructing blood flow in children 179 Operative considerations Since the development of catheter balloon dilation, operative valvotomy is indicated for those patients who have failed dilation (e.g patients with Noonan syndrome with dysplastic valves) or who are not candidates for balloon dilation (e.g the neonate with critical stenosis and an extremely hypoplastic pulmonary annulus instead requires outflow tract widening by use of a patch) Infundibular narrowing may require excision in some patients Summary Pulmonary stenosis can usually be diagnosed on the basis of clinical and laboratory findings Cardiac catheterization is required to determine precisely the severity and to perform balloon valvotomy in patients with moderate or severe stenosis; it can be performed at low risk and with excellent results Pulmonary stenosis secondary to dysplastic pulmonary valve This distinctive form of pulmonary stenosis accounts for less than 10% of valvar pulmonary stenosis Anatomically, the commissures of the pulmonary valve leaflets are not fused as in most examples of stenotic valves Rather, the commissures are open, but each leaflet is greatly thickened and redundant The valvar obstruction is caused by the bulk of valvar tissue within the pulmonary annulus The pulmonary annulus can also be reduced in diameter Poststenotic dilation usually does not occur History The history is similar to that of patients with pulmonary stenosis with a domeshaped pulmonary valve Physical examination In many patients, dysplastic pulmonary valve is associated with various syndromes, such as Noonan syndrome (see Chapter 2) Auscultation shows a pulmonary systolic ejection murmur, usually grades 2/6-4/6 Poststenotic dilation and a systolic ejection click are not found The P2 is soft and delayed Electrocardiogram The electrocardiogram is distinctive The QRS axis is almost always superiorly directed (−60∘ to −150∘ ) and distinguishes the dysplastic from dome-shaped pulmonary stenosis, in which the QRS axis rarely exceeds +180∘ The reason 180 Pediatric cardiology for this alteration of the QRS axis is unknown but may represent an abnormal location of the conduction system Right ventricular hypertrophy is present, its degree reflecting the level of right ventricular systolic pressure Right atrial enlargement may appear Chest X-ray The heart size is normal, as is the vascularity The pulmonary arterial segment is of normal size compared with dome-shaped valvar pulmonary stenosis Natural history In this form of pulmonary stenosis, the stenotic valve orifice probably grows in relation to the growth of the child Changes that occur with age are related to the effects of the elevated right ventricular systolic pressure and right ventricular hypertrophy upon the right ventricle, to the frequent development of severe infundibular stenosis, and perhaps to changes in the pliability of the thickened valve leaflets themselves Echocardiogram In patients with a so-called dysplastic valve, the leaflets may be so thick that they appear globular, with very little motion or opening during systole Some patients have biventricular hypertrophy disproportionate to the degree of outflow obstruction Although this finding may represent a form of hypertrophic cardiomyopathy for patients with Noonan syndrome, it has a more benign natural history than in idiopathic forms Cardiac catheterization The data resemble those obtained in dome-shaped pulmonary stenosis Angiography confirms the dysplastic nature of the valve as the leaflets appear thickened and immobile The pulmonary artery is only slightly enlarged Balloon dilation is not effective in most patients Operative considerations The indications for operation are similar to those for dome-shaped pulmonary stenosis; however, the operative approach is different Valvotomy cannot be performed because commissural fusion is not present One or two leaflets must be excised, and in some patients a patch must be placed across the annulus to widen this area of right ventricular outflow Resection of infundibular muscle often accompanies valvotomy Conditions obstructing blood flow in children 181 Peripheral pulmonary artery stenosis Stenosis also occurs in the pulmonary artery branches One or more major branches may be involved, usually showing a long area of narrowing, or the entire pulmonary arterial tree may be hypoplastic The most common type is neonatal pulmonary artery stenosis The branch pulmonary arteries are small in relation to the pulmonary trunk, so there is mild obstruction from a discrepancy in size Over the first 3–6 months of life, the branches increase in size and evidence of the obstruction (murmur) disappears Peripheral pulmonary artery stenosis occurs in other conditions, including congenital rubella syndrome and supravalvar aortic stenosis, particularly in patients with Williams syndrome and Alagille syndrome (with a clinical presentation similar to biliary atresia) Hypoplastic pulmonary arteries frequently accompany tetralogy of Fallot with pulmonary valve atresia; the patients concerned often have DiGeorge syndrome History Most patients with this condition are asymptomatic unless other conditions, such as Williams syndrome, are present Physical examination Features of one of the syndromes mentioned above may be discovered In normal neonates with auscultatory findings of peripheral pulmonary artery “stenosis,” the murmur disappears with time (see Chapter 1), and the pulmonary arteries are, in fact, normal The classic finding is a systolic ejection murmur present under the clavicles that is well heard throughout the lung fields and the axillae Typically, either no murmur, or only a soft murmur, is heard over the precordium The second heart sound is normal, and a systolic ejection click is not heard because the pulmonary artery is not dilated Electrocardiogram No features distinguish peripheral pulmonary artery stenosis from valvar pulmonary stenosis Right ventricular hypertrophy exists proportional to the degree of stenosis Chest X-ray This usually appears normal Pulmonary blood flow appears symmetric because most children have symmetric stenoses 182 Pediatric cardiology Natural history The prognosis is extremely variable Since the degree of stenosis is often mild and does not increase with age in most patients, it has been considered a benign condition Apparent growth of the pulmonary arteries does occur in some patients and results in clinical and laboratory features becoming more normal with age Rarely, especially in patients with Williams syndrome, stenosis may progress in severity and can cause suprasystemic right ventricular pressure and eventual right heart failure Echocardiogram The proximal few centimeters of each branch pulmonary artery are easily seen on the cross-sectional echocardiogram, particularly in young infants, and precise diameter measurements can be made Doppler is used to estimate pressure gradients within the branch pulmonary arteries; however, the Bernoulli equation is more applicable to discrete stenoses, so gradient estimates of long tubular (or serial) stenoses are often inaccurate Cardiac catheterization Oxygen data are normal Pressure tracings show a systolic gradient within the pulmonary arteries Diastolic pressures are identical proximal and distal to the obstruction The anatomic details are shown by pulmonary arteriography Catheter balloon dilation, sometimes with placement of endovascular metal stents, is widely used, although with variable results that depend greatly on the etiology and severity of the stenosis Operative considerations Most patients not require operation as the degree of stenosis is not severe In patients with severe obstruction, operation often cannot be performed because anatomic features, such as diffuse hypoplasia of the pulmonary arteries or multiple areas of stenosis, preclude an operative approach and are best served by having catheter balloon dilation Summary of obstructive lesions In each of the conditions discussed, turbulence occurs through a narrowed orifice, causing a systolic ejection murmur Beyond the obstruction, poststenotic dilation occurs; this is evidenced either by chest X-ray findings or by an ejection click The restricted orifice leads to elevation of systolic Williams (supravalvar AS) Noonan M>F M=F Aortic stenosis Pulmonary stenosis Birth Birth Infancy Turner M>F Coarctation of aorta Malformation Age Murmur Major Gender Syndrome History Table 5.1 Summary of Obstructive Lesions ± ± ± None, or exercise intolerance, variable cyanosis (neonates) None, or chest pain, syncope, sudden death None, or headache Congestive Cardiac Failure Symptoms Normal, or narrow pulse pressure Normal Diminished in legs Murmur Systolic Ejection Click (continued) Systolic, Aortic (if precordium and bicuspid back valve present) Suprasternal Systolic ejection, Aortic notch aortic area and and/or left sternal aortic area border Pulmonic area Systolic ejection, Pulmonic pulmonic area and left back Suprasternal notch Blood Pressure Thrill Physical Examination Conditions obstructing blood flow in children 183 Normal Normal of right Aortic stenosis Pulmonary stenosis Normal or right None or left None or left Atrial Enlargement Right Left Right (neonate and infant), left (older child) Ventricular Hypertrophy/ Enlargement Electrocardiogram Strain pattern if severe Strain pattern if severe Strain pattern if severe Other F, female; M, male; htn, hypertension; ± may be present or absent Normal Axis (QRS) Coarctation of aorta Malformation Table 5.1 (continued) Absent Present Absent unless bicuspid valve Aortic Enlargement Present Absent Absent None ± Left ventricle ± Right ventricle Other Poststenotic dilatation descending aorta None ± Left ventricle Chamber Enlargement Chest X-ray Pulmonary Artery Enlargement 184 Pediatric cardiology Conditions obstructing blood flow in children pressures proximally and to ventricular hypertrophy The clinical and laboratory findings reflecting this hypertrophy permit assessment of the severity of the condition (Table 5.1) In patients with moderate or severe obstruction gradient, relief can be performed successfully by operative and catheterization means 185 ... 97 11 0 11 4 12 2 98 11 2 11 6 12 3 95 10 8 11 2 12 0 96 11 0 11 4 12 1 97 11 1 11 5 12 2 99 11 2 11 6 12 3 10 0 11 4 11 8 12 5 96 11 0 11 4 12 1 98 11 1 11 5 12 3 99 11 3 11 7 12 4 10 0 11 4 11 8 12 5 10 2 11 5 11 9 12 7 98 11 1 11 5... 11 0 11 4 12 1 98 11 2 11 5 12 3 93 10 6 11 0 11 7 94 10 8 11 1 11 9 96 10 9 11 3 12 0 98 11 1 11 5 12 2 10 0 11 3 11 7 12 4 94 10 7 11 1 11 8 96 10 9 11 3 12 0 97 11 1 11 5 12 2 99 11 3 11 6 12 3 10 1 11 4 11 8 12 5 95 10 9 11 2 12 0... 13 4 11 1 12 2 12 6 13 3 11 0 12 3 12 7 13 4 11 1 12 4 12 8 13 5 11 1 12 5 12 9 13 6 11 3 12 4 12 7 13 5 11 1 12 5 12 9 13 6 11 2 12 6 13 0 13 7 11 3 12 6 13 0 13 7 11 4 12 5 12 9 13 6 11 3 12 6 13 0 13 7 11 4 12 7 13 1 13 8 11 4 12 7 13 1 13 8