Catheterization and Cardiovascular Diagnosis 4:289-296
(1978)
Restrictive Cardiomyopathy in an Infant With Massive Biatrial Enlargement and Normal Ventricular Size and Pump Function Harold G. Erath, Jr, MD, Thomas P. Graham, Jr, MD, Clyde W. Smith, MD, and Robert J. Boucek, Jr, MD Restrlctive cardiomyopathy in an infant wlth massive blatriai enlargement and normal ventricular size has been reported only once previously L3j. We now present a 13month-old patient wlth severe and progressive congestive heart failure who demonstrated normal ventricular cavity size with blatrial enlargement. Ejection fraction end echocardiographic ventricular function studies were normal. Key words: restrictive cardiomyopathy, quantifying ventricular size and function, echocardiq raphy, biatrial enlargement
INTRODUCTION
Primary myocardial disease in infants and children, defined as a disorder of heart muscle of unknown cause or association [ 1,2], has generated considerable interest recently [2-8]. Classifications vary among authors but generally include patients with hypertrophic obstructive and nonobstructive cardiomyopathy , endocardia1 fibroelastosis, endomyocardial fibrosis, and idiopathic myocarditis. Harris, Rodin, and Nghiem [3] reported a 5-year-old girl with restrictive cardiomyopathy characterized by biatrial enlargement with tall “a” waves in both atria, “normal-sized” ventricular cavities, and increased resistance to ventricular filling. There was no evidence of mitral or tricuspid stenosis. To our knowledge no similar case of restrictive cardiomyopathy has been reported in childhood. The purpose of this report is to present quantitative angiocardiographic data demonstrating normal right and left ventricular size and ejection fraction in an
From Vanderbiit University School of Medicine, Nashville, Tennessee.
Address reprint requests to Thomas P. Graham, Jr, MD, Div of Pediatric Cardiology, Vanderbilt Hospital, Nashville, TN 37232. Received for publication December 19, 1977; accepted March 13, 1978.
0098-6569/78/0403-0289$01.70 @ 1978 Alan R. Lia, Inc
290
Erath et al
infant who presented with severe cardiomegaly and congestive heart failure. The catheterization findings and clinical course suggest a restrictive cardiomyopathy syndrome similar to that reported by Harris and associates [3]. CASE REPORT
This 13-month-old white male was the product of an uncomplicated pregnancy, labor, and delivery, and had an uneventful neonatal course. His karyotype and mental development were normal. The family history was negative for congenital heart disease. On physical examination, his pulse was 130 and respiratory rate 54. He was below the third percentile for height and weight, but head circumference was normal. There were pronounced webbing of the neck and diffuse joint stiffness with 1.5" hip flexion contractures. He had bilateral basilar wheezes and rales. The first and second heart sounds were normal and no murmur or gallop was detected. There was hepatomegaly to 3 cm below the right costal margin. Femoral pulses were normal. Chest X-ray (Fig ]),filmsdemonstrated cardiomegaly with a cardiothoracic ratio of 0.75. The electrocardiogram (Fig 2) showed sinus rhythm with first-degree atrioventricular block, right axis deviation, right ventricular hypertrophy, and
Fig 1. Frontal chest film at time of cardiac catheterization reveals cardiomegaly.
Restrictive Cardiomyopathy in an Infant
291
Fig 2. Electrocardiogram showing right axis deviation, rightventricular hypertrophy,and biatriai enlargement with diminished left ventricular forces.
biatrial enlargement. Diminished left ventricular forces and the deep, wide Q wave in V Sraised the question of an infarction. Mucopolysaccharide screen was negative and skin and muscle biopsies showed no pathologic changes. His hemotocrit was 52. ECHOCARDIOGRAPHY DATA
Echocardiography data included a left ventricular end-diastolic dimension of 23
mm, left ventricular posterior wall thickness of 6.5 mm, and ventricular septum thickness of 5.4 mm. The left ventricular shortening fraction was 0.39 and velocity of circumferential fiber shortening was 1.86. The left ventricular ratio of preejection period to ejection time was 0.30. These data are consistent with concentric hypertrophy of the left ventricle with normal Ieft ventricular function indices [16, 171. CATHETERIZATION DATA
Cardiac catheterization data are presented in Table I. The salient features are elevated left and right ventricular end-diastolic pressures and elevated atrial pressures. There were giant “a” waves in the atrial tracings. Biplane cineangiography (Figs 3-5) showed a thick-walled left ventricle that appeared normal in size and contracted normally. Its shape was somewhat abnormal. There were increased trabeculations, giving a spongy appearance to the
TABLE I. Cardiac Catheterization Data
Site Right atrium “a” wave Right ventricle Pulmonary artery Left atrium “a” wave Left ventricle
Press ti re
25-30, (20) 44-59122-27 47-68/28, (45) 29-40, (24) 95/26-42
0 2 Saturation
62 -
84 88
292
Erath et al
Fig 3. Posteroanterlor frame of the right ventricular cineangiocardiogram showing an enlarged right atrium.
Fig 4. Lateral frame of the left atrial cineangiocardlogram showing an enlarged left atrium (arrows).
Restrictive Cardiomyopathy in an Infant
293
Fig 5. Posteroanterior views of the left ventricle at end-diastole (A) and endsystole (B). The left ventricle is of normal slze and contracts normally. There is minimal mitral regurgitation. The coronary arteries arise normally.
294
Erath et al
endocardial surface. Mild mitral regurgitation was present. Coronary artery anatomy was normal, as were the aortic arch and arch vessels. The right ventricular chamber also appeared normal in size and contraction. The pulmonary valve and pulmonary vascular tree were normal. Marked tricuspid regurgitation was present, but the tricuspid leaflets were normally placed. The right and left atria were extremely dilated. Ventricular and atrial volumes were calculated and compared to normal data using previously described techniques [ 13-15], Massive atrial dilatation with normal ventricular cavity size and ejection fraction are shown (Table 11). Left ventricular wall mass was 143% of normal. The child was treated with digitalis and diuretics with poor control of his chronic congestive heart failure. His congestive failure worsened and the cardiothoracic ratio increased to 0.81. He died at home nine months after the initial presentation. Autopsy permission was not granted. DISCUSSION
Restrictive cardiomyopathies are endocardial or myocardial diseases of unknown etiology wherein the characteristic defect is impaired ventricular filling in the absence of atrioventricular valve stenosis. This patient represents the first reported pediatric case in which normal ventricular size and pump function together with severe biatrial enlargement have been quantified. The features of the case presented here are sufficiently similar to the case of restrictive cardiomyopathy reported by Harris and associates [3] to warrant grouping it with their case as a specific syndrome. Though our patient was younger, the clinical courses, poor control by digitalis and diuretics, and death within a year of presentation were similar. The electrocardiogram showed biatrial enlargement and question of ischemic injury to the left ventricle in both cases. Each case evidenced marked enlargement of the atria, normal or small ventricular cavities, and no mitral or tricuspid stenosis. There was no evidence of ventricular outflow obstruction. Functionally, there were tall “a” waves in both atria and elevated end-diastolic TABLE II. Quantification of Cardiac Catheterization Data
Site
Determination
Value
‘jr, Nor ma1
End-diastolic vol. End-s y stolic vol. Stroke vol. Systolic output Ejection fraction Wall mass
51 ml/m2 I I ml/mz 40 ml/mz 5.03 liters/min/m2 0.78 I28 gm/m2
118 114 143
LA
Maximal vol.
98 ml/m2
325
52 ml/m2 9 ml/m2 4 4 ml/m2 5.178 liters/min/m2 0.84
114
RV
End-diastolic vol. End-systolic vol. Stroke vol. Systolic output Ejection fraction Maximal vol.
142 ml/m2
343
LV
RA
88 -
-
136 123
Restrictive Cardiomyopathy in an Infant
295
pressures in both ventricles. Left ventricular pump function in our case was evaluated as normal on the basis of echocardiographic and cineangiographic data. Similar conditions have been reported in the literature but important differences remain. These conditions include the contracted type of endocardial fibroelastosis, South African-type cardiomyopathy , endomyocardial fibrosis, and hypertrophic obstructive cardiomyopathy. Lynfield et al [12] presented two autopsied cases of the rare contracted type of endocardial fibroelastosis with chronic congestive heart failure, cardiomegaly , hepatomegaly , biatrial enlargement, and right ventricular hypertrophy. At cardiac catheterization neither patient had increased right atrial pressures or right ventricular diastolic pressures as our patient did. Autopsy showed a hypertrophied left ventricle and a small cavity. Dilatation and fibroelastosis of the left atrium were present. Both cases had marked dilatation of the right ventricle in contrast to our case. Edwards et al [9] also presented a patient with a contracted “endocardial sclerosis” who had a similar course. The left ventricular chamber was normal-sized by subjective assessment and the left atrium was dilated. Chamber pressures, function status of the left ventricle, and right heart size and function are not known. Stein et al [ 101 reviewed 23 children with South African-type cardiomyopathy. The electrocardiogram showed left ventricular hypertrophy in “most instances” with T wave inversion in 12 patients. Autopsy showed biventricular hypertrophy and biatrial enlargement in 12 patients. However, biventricular dilatation was present also. Endomyocardial fibrosis evidences dense fibrosis and endocardial destruction affecting the contractile properties of the heart [ 11, 31. In our case the degree of filling resistance manifested by both ventricles, the massive biatrial dilatation, the lack of left ventricular hypertrophy revealed on the electrocardiogram, and the lack of asymmetrical septa1 hypertrophy would be inconsistent with hypertrophic nonobstructive or obstructive cardiomyopathies. The case presented here is similar to the case presented by Harris and associates and portrays the rare occurrence of massive biatrial enlargement with normal-sized ventricular cavities and normal biventricular pump function according to ejection fraction and echocardiographic criteria. Severe congestive heart failure was poorly responsive to treatment, and death occurred in both cases within one year following diagnosis. Etiology remains entirely unknown at present. REFERENCES 1. Goodwin JF, Oakley CM: The cardiomyopathies. Br Heart J 34545. 1972. 2. Harris LC, Nghiem QX: Cardiomyopathies in infants and children. In Fnedman WF, Lesch M, Sonnenblick EH (eds): “Neonatal Heart Disease.” New York: Grune and Stratton. 1973, pp 191-223. 3. Harris LC, Rodin AE, Nghiem QX: Idopathic. non obstructive cardiomyopathy in children. Am J Cardiol 21:153, 1968. 4. Freundlich E. Munk J . Griffel B , Steinlauf J : Primary myocardial disease in infancy. Am J Cardiol 13:721, 1964. 5. Idiopathic cardiomyopathy in infants. Br Med J 1:63, 1973. 6. Doshi R, Lodge KV: Idiopathic cardiomyopathy in infants. Arch Dis Child 48:431. 1973. 7. Greenwood RD, Nadas A S , Fyler DC: The clinical course of primary myocardial disease in infants and children. Am Heart J 92:549, 1976.
296
Erath et al
8. Phornphutkul C, Rosenthal A, Nadas AS: Cardiomyopathy in Noonan’s syndrome. Br Heart J 3 5 9 , 1973. 9. Edwards JE, Dry TJ, Parker RL, Burchell HB, Wood EH, Bulbulian AH: “An Atlas ofcongenital Anomalies of the Heart and Great Vessels.” Springfield, Illinois: CC Thomas, 1954, pp 31-34. 10. Stein H , Shnier MH, Wayburne S, Isaccson C: Cardiomyopathy in African children. Arch Dis Child 39:610, 1964. 1 1 . Abrahams DG: Endomyocardial fibrosis of the right ventricle. Quart J Med 31:1, 1969. 12. Lynfield J , Gasul B, Luan L. Dillon R: Right and left heart catheterization and angiographic findings in idiopathic cardiac hypertrophy with endocardial fibroelastosis. Circulation 21:386, 1960. 13. Graham TP Jr, Jarmakani JM, Atwood GF, Canent RV Jr: Right ventricular volume determinations in children: Normal values and observations with volume or pressure overload. Circulation 47: 144, 1973. 14. Graham TP J r , Atwood GF, Faulkner SL, Nelson JF: Right atrial volume measurements from biplane cineangiocardiography: Methodology, normal values, and alterations with pressure or volume overload. Circulation 49:709, 1974. 15. Graham TP Jr, Lewis BW. Jarmakani JM, Canent RV Jr, Capp MP: Left heart volume and mass quantification in children with left ventricular pressure overload. Circulation 41:203, 1970. 16. Gutgesell HP, Paquet M, Duff D, McNamara D: Evaluation of left ventricular size and function by echocardiography. Circulation 56:457, 1977. 17. Epstein ML, Goldberg SJ, Allen HD, Konecke L, Wood J: Great vessel, cardiac chamber. and wall growth patterns in normal children. Circulation 51: 1124, 1975.
(1978)
Restrictive Cardiomyopathy in an Infant With Massive Biatrial Enlargement and Normal Ventricular Size and Pump Function Harold G. Erath, Jr, MD, Thomas P. Graham, Jr, MD, Clyde W. Smith, MD, and Robert J. Boucek, Jr, MD Restrlctive cardiomyopathy in an infant wlth massive blatriai enlargement and normal ventricular size has been reported only once previously L3j. We now present a 13month-old patient wlth severe and progressive congestive heart failure who demonstrated normal ventricular cavity size with blatrial enlargement. Ejection fraction end echocardiographic ventricular function studies were normal. Key words: restrictive cardiomyopathy, quantifying ventricular size and function, echocardiq raphy, biatrial enlargement
INTRODUCTION
Primary myocardial disease in infants and children, defined as a disorder of heart muscle of unknown cause or association [ 1,2], has generated considerable interest recently [2-8]. Classifications vary among authors but generally include patients with hypertrophic obstructive and nonobstructive cardiomyopathy , endocardia1 fibroelastosis, endomyocardial fibrosis, and idiopathic myocarditis. Harris, Rodin, and Nghiem [3] reported a 5-year-old girl with restrictive cardiomyopathy characterized by biatrial enlargement with tall “a” waves in both atria, “normal-sized” ventricular cavities, and increased resistance to ventricular filling. There was no evidence of mitral or tricuspid stenosis. To our knowledge no similar case of restrictive cardiomyopathy has been reported in childhood. The purpose of this report is to present quantitative angiocardiographic data demonstrating normal right and left ventricular size and ejection fraction in an
From Vanderbiit University School of Medicine, Nashville, Tennessee.
Address reprint requests to Thomas P. Graham, Jr, MD, Div of Pediatric Cardiology, Vanderbilt Hospital, Nashville, TN 37232. Received for publication December 19, 1977; accepted March 13, 1978.
0098-6569/78/0403-0289$01.70 @ 1978 Alan R. Lia, Inc
290
Erath et al
infant who presented with severe cardiomegaly and congestive heart failure. The catheterization findings and clinical course suggest a restrictive cardiomyopathy syndrome similar to that reported by Harris and associates [3]. CASE REPORT
This 13-month-old white male was the product of an uncomplicated pregnancy, labor, and delivery, and had an uneventful neonatal course. His karyotype and mental development were normal. The family history was negative for congenital heart disease. On physical examination, his pulse was 130 and respiratory rate 54. He was below the third percentile for height and weight, but head circumference was normal. There were pronounced webbing of the neck and diffuse joint stiffness with 1.5" hip flexion contractures. He had bilateral basilar wheezes and rales. The first and second heart sounds were normal and no murmur or gallop was detected. There was hepatomegaly to 3 cm below the right costal margin. Femoral pulses were normal. Chest X-ray (Fig ]),filmsdemonstrated cardiomegaly with a cardiothoracic ratio of 0.75. The electrocardiogram (Fig 2) showed sinus rhythm with first-degree atrioventricular block, right axis deviation, right ventricular hypertrophy, and
Fig 1. Frontal chest film at time of cardiac catheterization reveals cardiomegaly.
Restrictive Cardiomyopathy in an Infant
291
Fig 2. Electrocardiogram showing right axis deviation, rightventricular hypertrophy,and biatriai enlargement with diminished left ventricular forces.
biatrial enlargement. Diminished left ventricular forces and the deep, wide Q wave in V Sraised the question of an infarction. Mucopolysaccharide screen was negative and skin and muscle biopsies showed no pathologic changes. His hemotocrit was 52. ECHOCARDIOGRAPHY DATA
Echocardiography data included a left ventricular end-diastolic dimension of 23
mm, left ventricular posterior wall thickness of 6.5 mm, and ventricular septum thickness of 5.4 mm. The left ventricular shortening fraction was 0.39 and velocity of circumferential fiber shortening was 1.86. The left ventricular ratio of preejection period to ejection time was 0.30. These data are consistent with concentric hypertrophy of the left ventricle with normal Ieft ventricular function indices [16, 171. CATHETERIZATION DATA
Cardiac catheterization data are presented in Table I. The salient features are elevated left and right ventricular end-diastolic pressures and elevated atrial pressures. There were giant “a” waves in the atrial tracings. Biplane cineangiography (Figs 3-5) showed a thick-walled left ventricle that appeared normal in size and contracted normally. Its shape was somewhat abnormal. There were increased trabeculations, giving a spongy appearance to the
TABLE I. Cardiac Catheterization Data
Site Right atrium “a” wave Right ventricle Pulmonary artery Left atrium “a” wave Left ventricle
Press ti re
25-30, (20) 44-59122-27 47-68/28, (45) 29-40, (24) 95/26-42
0 2 Saturation
62 -
84 88
292
Erath et al
Fig 3. Posteroanterlor frame of the right ventricular cineangiocardiogram showing an enlarged right atrium.
Fig 4. Lateral frame of the left atrial cineangiocardlogram showing an enlarged left atrium (arrows).
Restrictive Cardiomyopathy in an Infant
293
Fig 5. Posteroanterior views of the left ventricle at end-diastole (A) and endsystole (B). The left ventricle is of normal slze and contracts normally. There is minimal mitral regurgitation. The coronary arteries arise normally.
294
Erath et al
endocardial surface. Mild mitral regurgitation was present. Coronary artery anatomy was normal, as were the aortic arch and arch vessels. The right ventricular chamber also appeared normal in size and contraction. The pulmonary valve and pulmonary vascular tree were normal. Marked tricuspid regurgitation was present, but the tricuspid leaflets were normally placed. The right and left atria were extremely dilated. Ventricular and atrial volumes were calculated and compared to normal data using previously described techniques [ 13-15], Massive atrial dilatation with normal ventricular cavity size and ejection fraction are shown (Table 11). Left ventricular wall mass was 143% of normal. The child was treated with digitalis and diuretics with poor control of his chronic congestive heart failure. His congestive failure worsened and the cardiothoracic ratio increased to 0.81. He died at home nine months after the initial presentation. Autopsy permission was not granted. DISCUSSION
Restrictive cardiomyopathies are endocardial or myocardial diseases of unknown etiology wherein the characteristic defect is impaired ventricular filling in the absence of atrioventricular valve stenosis. This patient represents the first reported pediatric case in which normal ventricular size and pump function together with severe biatrial enlargement have been quantified. The features of the case presented here are sufficiently similar to the case of restrictive cardiomyopathy reported by Harris and associates [3] to warrant grouping it with their case as a specific syndrome. Though our patient was younger, the clinical courses, poor control by digitalis and diuretics, and death within a year of presentation were similar. The electrocardiogram showed biatrial enlargement and question of ischemic injury to the left ventricle in both cases. Each case evidenced marked enlargement of the atria, normal or small ventricular cavities, and no mitral or tricuspid stenosis. There was no evidence of ventricular outflow obstruction. Functionally, there were tall “a” waves in both atria and elevated end-diastolic TABLE II. Quantification of Cardiac Catheterization Data
Site
Determination
Value
‘jr, Nor ma1
End-diastolic vol. End-s y stolic vol. Stroke vol. Systolic output Ejection fraction Wall mass
51 ml/m2 I I ml/mz 40 ml/mz 5.03 liters/min/m2 0.78 I28 gm/m2
118 114 143
LA
Maximal vol.
98 ml/m2
325
52 ml/m2 9 ml/m2 4 4 ml/m2 5.178 liters/min/m2 0.84
114
RV
End-diastolic vol. End-systolic vol. Stroke vol. Systolic output Ejection fraction Maximal vol.
142 ml/m2
343
LV
RA
88 -
-
136 123
Restrictive Cardiomyopathy in an Infant
295
pressures in both ventricles. Left ventricular pump function in our case was evaluated as normal on the basis of echocardiographic and cineangiographic data. Similar conditions have been reported in the literature but important differences remain. These conditions include the contracted type of endocardial fibroelastosis, South African-type cardiomyopathy , endomyocardial fibrosis, and hypertrophic obstructive cardiomyopathy. Lynfield et al [12] presented two autopsied cases of the rare contracted type of endocardial fibroelastosis with chronic congestive heart failure, cardiomegaly , hepatomegaly , biatrial enlargement, and right ventricular hypertrophy. At cardiac catheterization neither patient had increased right atrial pressures or right ventricular diastolic pressures as our patient did. Autopsy showed a hypertrophied left ventricle and a small cavity. Dilatation and fibroelastosis of the left atrium were present. Both cases had marked dilatation of the right ventricle in contrast to our case. Edwards et al [9] also presented a patient with a contracted “endocardial sclerosis” who had a similar course. The left ventricular chamber was normal-sized by subjective assessment and the left atrium was dilated. Chamber pressures, function status of the left ventricle, and right heart size and function are not known. Stein et al [ 101 reviewed 23 children with South African-type cardiomyopathy. The electrocardiogram showed left ventricular hypertrophy in “most instances” with T wave inversion in 12 patients. Autopsy showed biventricular hypertrophy and biatrial enlargement in 12 patients. However, biventricular dilatation was present also. Endomyocardial fibrosis evidences dense fibrosis and endocardial destruction affecting the contractile properties of the heart [ 11, 31. In our case the degree of filling resistance manifested by both ventricles, the massive biatrial dilatation, the lack of left ventricular hypertrophy revealed on the electrocardiogram, and the lack of asymmetrical septa1 hypertrophy would be inconsistent with hypertrophic nonobstructive or obstructive cardiomyopathies. The case presented here is similar to the case presented by Harris and associates and portrays the rare occurrence of massive biatrial enlargement with normal-sized ventricular cavities and normal biventricular pump function according to ejection fraction and echocardiographic criteria. Severe congestive heart failure was poorly responsive to treatment, and death occurred in both cases within one year following diagnosis. Etiology remains entirely unknown at present. REFERENCES 1. Goodwin JF, Oakley CM: The cardiomyopathies. Br Heart J 34545. 1972. 2. Harris LC, Nghiem QX: Cardiomyopathies in infants and children. In Fnedman WF, Lesch M, Sonnenblick EH (eds): “Neonatal Heart Disease.” New York: Grune and Stratton. 1973, pp 191-223. 3. Harris LC, Rodin AE, Nghiem QX: Idopathic. non obstructive cardiomyopathy in children. Am J Cardiol 21:153, 1968. 4. Freundlich E. Munk J . Griffel B , Steinlauf J : Primary myocardial disease in infancy. Am J Cardiol 13:721, 1964. 5. Idiopathic cardiomyopathy in infants. Br Med J 1:63, 1973. 6. Doshi R, Lodge KV: Idiopathic cardiomyopathy in infants. Arch Dis Child 48:431. 1973. 7. Greenwood RD, Nadas A S , Fyler DC: The clinical course of primary myocardial disease in infants and children. Am Heart J 92:549, 1976.
296
Erath et al
8. Phornphutkul C, Rosenthal A, Nadas AS: Cardiomyopathy in Noonan’s syndrome. Br Heart J 3 5 9 , 1973. 9. Edwards JE, Dry TJ, Parker RL, Burchell HB, Wood EH, Bulbulian AH: “An Atlas ofcongenital Anomalies of the Heart and Great Vessels.” Springfield, Illinois: CC Thomas, 1954, pp 31-34. 10. Stein H , Shnier MH, Wayburne S, Isaccson C: Cardiomyopathy in African children. Arch Dis Child 39:610, 1964. 1 1 . Abrahams DG: Endomyocardial fibrosis of the right ventricle. Quart J Med 31:1, 1969. 12. Lynfield J , Gasul B, Luan L. Dillon R: Right and left heart catheterization and angiographic findings in idiopathic cardiac hypertrophy with endocardial fibroelastosis. Circulation 21:386, 1960. 13. Graham TP Jr, Jarmakani JM, Atwood GF, Canent RV Jr: Right ventricular volume determinations in children: Normal values and observations with volume or pressure overload. Circulation 47: 144, 1973. 14. Graham TP J r , Atwood GF, Faulkner SL, Nelson JF: Right atrial volume measurements from biplane cineangiocardiography: Methodology, normal values, and alterations with pressure or volume overload. Circulation 49:709, 1974. 15. Graham TP Jr, Lewis BW. Jarmakani JM, Canent RV Jr, Capp MP: Left heart volume and mass quantification in children with left ventricular pressure overload. Circulation 41:203, 1970. 16. Gutgesell HP, Paquet M, Duff D, McNamara D: Evaluation of left ventricular size and function by echocardiography. Circulation 56:457, 1977. 17. Epstein ML, Goldberg SJ, Allen HD, Konecke L, Wood J: Great vessel, cardiac chamber. and wall growth patterns in normal children. Circulation 51: 1124, 1975.
