Two-dimensional echocardiographic findings in double orifice mitral valve

Between December 1981 and April 1984, five children ranging in age from 1 month to 5 1/2 years examined by two-dimensional echocardiography appeared to have a double orifice mitral valve. The diagnosis was verified in one patient at surgery, one patient by angiography and one patient by necropsy. Associated malformations included mitral stenosis and regurgitation, coarctation of the aorta, ostium primum and secundum atrial septal defect, ventricular septal defect and hypoplastic left heart syndrome. Three varieties of double orifice mitral valve were observed: an incomplete bridge type (one patient), in which a small strand of tissue connected the anterior and posterior leaflets at the leaflet edge level; a complete bridge type (three patients), in which a fibrous bridge divided the atrioventricular orifice completely into equal or unequal parts and a hole type (one patient), in which an additional orifice with subvalvular apparatus occurred in the posterior commissure of the mitral valve. These three types could be distinguished by sweeping the transducer in cross-sectional view from the apex toward the base of the heart. Both orifices could be seen throughout the scan in the complete bridge type while in the incomplete bridge type the two orifices could be seen only at the level of the papillary muscles. In the hole type, the second orifice was seen at about midleaflet level. In all three types, the chordae surrounding each orifice attached to only one papillary muscle. Congenital mitral stenosis or regurgitation was evident in three patients. The type of the double orifice mitral valve did not predict the presence or severity of symptoms.     

Use of Hancock porcine xenografts in children and adolescents

Between January 1,1974 and December 31,1978,47 xenografts (8 aortic, 28 mitral, 4 tricuspid, 3 left atrioventricular valve in I-transposition of the great arteries and 3 aortic-mitral) were implanted in 44 patients, aged 10/12 to 20 5/12 years (median 12 2/12). All eight patients with aortic valve replacement survived and were followed up for 22.5 ± 10.4 months (mean ± standard error of the mean). At postoperative cardiac catheterization in three patients, the peak systolic ejection gradient ranged between 24 and 38 mm Hg and the valve area index between 0.71 and 1.15 cm²/m². Among 26 patients who underwent mitral valve replacement, 5 died operatively and 2 died 2 months postoperatively, leaving 19 long-term survivors who were followed up for 26.2 ± 15.6 months. In the 11 patients who underwent postoperative cardiac catheterization, the mean diastolic gradient was 6.1 ± 2.7 mm Hg and the mean valve index 1.79 ± 0.76 cm²/m². Severe subaortic obstruction, due to the prosthetic mitral valve, occurred in three of five patients less than 5 years old.Among four patients who underwent tricuspid valve replacement there were no operative deaths; complete heart block occurred in three. At postoperative catheterization in two patients, the mean diastolic gradient was 3 and 5 mm Hg, and the valve index 1.32 and 1.7 cm²/m², respectively. Three patients with I-transposition of the great arteries who underwent replacement of the systemic atrioventricular valve were followed up for 12 to 37 months. At postoperative catheterization the mean diastolic gradient was 0 to 4 mm Hg and the valve index ranged from 1.68 to 1.88 cm²/m². Both aortic and mitral valves were replaced in three children. One died at operation and one 6 months after operation. The survivor has complete heart block but is in New York Heart Association functional class I.Eight xenografts (6 mitral, 1 left atrioventricular valve in I-transposition of the great arteries and 1 aortic) failed, requiring replacement 22 to 68 months after implantation. All were calcified to varying degrees. Valve failure began presenting 22 months after implantation, and of 25 valves implanted for 20 months or longer, 8 have been replaced. These 8 patients were younger (10.3 ± 0.2 years) at initial valve replacement than the other 17 patients (15.0 ± 0.3 years) followed up for 20 months or longer (p <0.05). High levels of γ-carboxyglutamic acid (GLA), a calciumbinding amino acid, were found in all six calcified xenografts analyzed, whereas none was found in a fresh porcine aortic valve or in an unimplanted xenograft. GLA-containing protein, laid down after implantation, may play a role in xenograft calcification.     

Conotruncal malformations: diagnosis in infancy using subxiphoid 2-dimensional echocardiography

Subxiphoid 2-dimensional echocardiography was performed and interpreted before the first cardiac catheterization in 109 of 113 infants less than 1 year of age with conotruncal malformations, situs solitus of the atria, and d-ventricular loop. The 4 remaining infants could not be examined using this technique for technical reasons.

In 104 of 109 patients successfully examined a correct diagnosis was obtained with the use of Subxiphoid 2-dimensional echocardiography. All patients with d-transposition of the great arteries had a correct diagnosis, and in 10 of 11 patients various types of double-outlet right ventricle were recognized by direct visualization of ventriculoarterial connection. Tetralogy of Fallot was correctly diagnosed in 34 of 36 patients and tetralogy of Fallot and pulmonary atresia were correctly diagnosed in 8 of 9 patients, on the basis of the position of the infundibular septum and presence or absence of continuity between the main pulmonary artery and the right ventricle. Five of 6 patients with truncus arteriosus communis were correctly diagnosed by demonstrating a connection between the pulmonary arteries and the ascending portion of the single large semilunar root. Subxiphoid 2-dimensional echocardiography proved to be a sensitive and specific technique for diagnosing conotruncal malformations in infancy.     

Left ventricular diastolic function in elite athletes with physiologic cardiac hypertrophy

Left ventricular hypertrophy due to aortic stenosis, hypertension and other forms of heart disease is associated with abnormalities of diastolic function. It is uncertain whether these changes are an inherent consequence of the hypertrophic process or represent additional pathologic factors. To investigate this issue, echocardiographic indexes of left ventricular early diastolic function in highly trained athletes were compared with those in age-matched normal control subjects. Athletes were equally classified into two groups: 11 swimmers who had a pattern of myocardial hypertrophy with normal wall thickness to dimension ratio and 11 power lifters whose wall thickness to dimension ratio was increased. The peak rates of left ventricular dimension increase and wall thinning in swimmers and power lifters were greater than in control subjects despite significantly higher left ventricular wall thickness and left ventricular mass index in the athletes. This increase in diastolic function indexes was associated with greater ventricular size and systolic performance. Normalization of the peak rate of dimension increase for end-diastolic dimension and adjustment of the peak rate of wall thinning for the fractional systolic thickening resolved any differences between groups. Thus, after the effects of ventricular size and systolic function were taken into consideration, diastolic function was normal in these subjects with considerable physiologic hypertrophy. This is in contrast to the findings in patients with hypertrophy associated with left ventricular pressure or volume overload, and suggests that abnormalities of diastolic function seen in pathologic hypertrophy are due to factors other than cardiac hypertrophy itself.     

Clinical and hemodynamic results of the Fontan operation for tricuspid atresia

Thirty patients aged 3 months to 26 years (median 9 years) with tricuspid atresia or severe tricuspid stenosis underwent a modified Fontan operation at Children's Hospital, Boston, between 1973 and 1980. Thirty-six palliative operations had been performed previously in 20 patients. Preoperative hemodynamic measurements included: mean pulmonary arterial pressure 6 to 18 mm Hg (median 9); pulmonary vascular resistance 0.3 to 2.2 Woods units/m² (median 1.5) and left ventricular end-diastolic pressure 3 to 14 mm Hg (median 7).There were five hospital deaths (17 percent), including two in the last 24 operations. The 25 survivors have been followed up for 4 to 85 months (median 23) with no late deaths. Twenty patients are in New York Heart Association class I and four in class II; one infant was not classified. Two patients have required reoperation, at, respectively, 71 and 26 months postoperatively; the former for late-developing conduit obstruction and residual bidirectional shunting; and the latter for a residual right to left shunt at atrial level. Early postoperative monitoring of hemodynamics in the intensive care unit revealed that a mean right atrial pressure of 17 mm Hg or greater, without obstruction of the anastomosis, was invariably associated with serious morbidity or mortality.Fifteen patients underwent elective cardiac catheterization 9 to 21 months (median 13) postoperatively. The mean right atrial pressure ranged between 5 and 12 mm Hg (median 8) and mean pulmonary arterial pressure between 4 and 11 mm Hg (median 7). The cardiac index (measured in 12 patients) was 1.9 to 4.0 liters/min per m² (median 3.2). The left ventricular ejection fraction measured in 11 patients did not change significantly postoperatively, remaining normal in 10. Three patients had a residual right to left shunt at atrial level while the arterial oxygen saturation in the remaining 12 patients was 93 to 97 percent. Thus the modified Fontan operation can be performed with excellent clinical and hemodynamic results in selected patients with tricuspid atresia.     

Two-dimensional echocardiographic assessment of caval and pulmonary venous pathways after the senning operation

This study reports the 2-dimensional echocardiographic appearance of the caval and pulmonary venous pathways after the Senning procedure in 28 patients and establishes normal values for the caval and pulmonary venous pathway dimensions. Eighteen patients had no caval or pulmonary venous obstruction or tricuspid regurgitation at catheterization; 2 had isolated superior vena caval obstruction, 3 had isolated pulmonary venous obstruction, 4 patients had severe tricuspid regurgitation, and 1 had a large residual ventricular septal defect. The caval and pulmonary venous pathways were imaged in modified 4-chamber and transverse views, and the narrowest dimension of each pathway in each view was measured by 2 independent observers. Dimension measurements were then normalized to the cube root of body surface area. Caval and pulmonary venous pathway “dimension products” were obtained by multiplying the normalized dimension in the 4-chamber view by the normalized dimension in the transverse view.All patients with catheterization-proven caval or pulmonary venous obstruction or tricuspid regurgitation had caval or pulmonary venous pathway dimension products outside the normal range, defined by our measurements in the 18 patients with no caval or pulmonary venous obstruction or tricuspid regurgitation. Thus, 2-dimensional echocardiography can provide both quantitative and qualitative information about the caval and pulmonary venous pathways after the Senning procedure.     

Subxyphoid 2-dimensional echocardiographic identification of left ventricular papillary muscle anomalies in complete common atrioventricular canal

Mitral valve dysfunction is probably the major cause of operative mortality from total repair of complete common atrioventricular (AV) canal in infancy. The presence of a solitary left ventricular (LV) papillary muscle appears to be 1 anatomic factor influencing the success of mitral reconstruction because suturing of the cleft between the superior and inferior components of the anterior mitral leaflet creates a parachute mitral valve deformity, which may result in stenosis or in unduly high tension on the components of the repair. This study reports on (1) the 2-dimensional (2-D) echocardiographic appearance of the LV papillary muscle architecture in patients with complete common AV canal compared with that in normal subjects, and (2) the incidence of solitary LV papillary muscle in patients with complete common AV canal.

Two-dimensional echocardiography was performed in 31 infants with complete common AV canal, 14 normal infants, and 9 infants with a large ventricular septal defect not involving the AV canal region. Of 31 infants with complete common AV canal, 26 (80%) had 2 LV papillary muscles on 2-D echocardiography, 3 (10%) had 3 LV papillary muscles, and 3 (10%) had 1 LV papillary muscle. In patients with 2 LV papillary muscles, the anterolateral papillary muscle was displaced posteriorly compared with that in normal subjects and in patients with ventricular septal defect, whereas the posteromedial papillary muscle was in its normal location.

Among the 25 patients with complete common AV canal with 2 LV papillary muscles, there was 1 operative death. Among the 6 infants with complete common AV canal with LV papillary muscle anomalies, 5 underwent surgical repair with 4 early deaths.

Subxyphoid 2-D echocardiography is a useful technique for evaluating LV papillary muscle architecture in complete common AV canal and permits identification of patients who may be at higher risk for unsuccessful mitral reconstruction.     

Use of prostaglandin E1 in infants with d-transposition of the great arteries and intact ventricular septum.

Prostaglandin E1 was used to treat five infants with d-transposition of the great arteries and intact ventricular septum who had persistent severe hypoxemia after the creation of an interatrial communication. Three infants had a dramatic improvement in systemic arterial oxygen saturation associated with dilation of the ductus arteriosus; in two of the three cases urgent surgery was avoided. Two infants had no clinical evidence of increased ductal shunting and no improvement in oxygen saturation. A trial of prostaglandin E1 is recommended for treatment of severe hypoxemia in infants with d-transposition of the great arteries with intact ventricular septum if the presence of a large atrial septal defect is established.     

Reversal of left ventricular hypertrophy in hypertensive patients treated with methyldopa. Lack of association with blood pressure control

Ten patients with essential hypertension and left ventricular hypertrophy were treated with relatively small doses of methyldopa (500 to 750 mg/day) added to long-term diuretic therapy. Sequential M mode echocardiography showed significant reduction in left ventricular mass 36 weeks after addition of methyldopa in four patients (359 +/- 77 [standard error of the mean] to 235 +/- 63 g) although blood pressure was not significantly altered by the added treatment. In three of these patients, reduction of left ventricular mass was observed as early as 12 weeks of treatment (384 to 262 g). Neither left ventricular mass to left ventricular volume ratio nor fractional shortening was significantly altered by reduction in left ventricular mass (3.21 +/- 0.26 to 2.74 +/- 0.24 and 0.42 +/- 0.03 to 0.44 +/- 0.02, respectively). There was no apparent relation in these patients between changes in blood pressure and changes in left ventricular mass. Thus, reversal of cardiac hypertrophy with antihypertensive treatment is possible in human beings; however, it seems to depend on other factors besides blood pressure control.     

Radionuclide angiocardiographic assessment of pulmonary vascular reactivity in patients with left to right shunt and pulmonary hypertension

Radionuclide angiocardiography was used to assess pulmonary vascular reactivity in eight patients (nine studies) with a large, relatively unrestrictive intracardiac defect and pulmonary arterial hypertension. Radionuclide angiocardiograms, using technetium-99m pertechnetate, were performed first with the patient breathing room air and then after 10 minutes of breathing a mixture containing 90 percent or more of oxygen. The pulmonary to systemic flow ratios obtained by gamma variate analysis of the radionuclide time-activity curves were compared with those calculated with the Fick principle at the time of cardiac catheterization. There was a good correlation between the two methods both in room air studies (r = 0.88) and in those obtained with 90 percent or more of oxygen (r = 0.94). All six studies (in five patients) with a reactive pulmonary vasculature (judged by a pulmonary vascular resistance at cardiac catheterization of less than 6 units/m2 with oxygen or after tolazoline) had a radionuclide pulmonary to systemic flow ratio of 3.0 or greater with oxygen. The three patients with a nonreactive pulmonary vasculature had a radionuclide pulmonary to systemic flow ratio of 2.3 or less with oxygen, a value that was unchanged from the room air value. These data suggest that radionuclide angiocardiography may be a useful, relatively noninvasive method of assessing pulmonary vascular reactivity in patients with a large, relatively unrestrictive intracardiac defect.     

2-Dimensional echocardiographic appearance of complete left-sided juxtaposition of the atrial appendages

This report describes the 2-dimensional (2-D) echocardiographic appearance of left-sided juxtaposition of the atrial appendages (JAA). From January 1, 1978, to June 30, 1979, 2 Infants had the diagnosis of left-sided JAA at autopsy. Both patients had previously been examined by subxiphoid 2-D echpcardlography. On review of these studies, the septum secundum was found to be oriented posteriorly in the transverse view of the atria. From July 1979 to June 1981, prospective evaluation of all infants for the presence of this finding revealed 2 more patients. Left-sided JAA was confirmed at surgery in 1 case and by selective right atrial angiography in the other. The diagnosis of left-sided JAA has important implications for both atrial baffle operations and for the Fontan procedure.     

Effects of enhanced afterload (methoxamine) and contractile state (dobutamine) on the left ventricular late-systolic wall stress-dimension relation

Although the left ventricular (LV) end-systolic pressure-dimension relation is a load-independent, sensitive index of contractile state, its accurate determination requires afterload manipulation. The slope value of the late-systolic stress-dimension relation determined under resting conditions has been suggested as an alternative index of contractility that can be assessed without pharmacologie intervention. To evaluate this relation, 14 normal subjects were studied by M-mode echocardiography, phonocardlography and indirect carotid pulse tracings during infusion of methoxamine to increase afterload. Seven of these subjects were also studied after infusion of dobutamine to increase contractility. Continuous systolic stress-dimension trajectories were computer generated from digitized tracings. The late-systolic portions of these curves were found to be linear and the slope and intercept were determined. The slope value was sensitive to both afterload and contractility, and the magnitude of change in slope value was relatively greater during afterload enhancement than during inotropic stimulation. A strong correlation of slope value with peak systolic stress was found. Thus, the late-systolic stress-dimension relation is linear with a slope value which is dependent on both LV contractility and afterload. Like other ejection phase indexes, the usefulness of this index is limited by its inability to distinguish changes in contractile state from alterations in loading conditions.     

Measurement of systemic and pulmonary blood flow and QP/QS ratio using Doppler and two-dimensional echocardiography

A noninvasive method for measuring systemic and pulmonary blood flow using Doppler velocimetry combined with 2-dimensional (2-D) echocardiography has been developed. High correlations were found between Fick- and Doppler-derived indexed measurements of systemic and pulmonary flow as well as the pulmonary to systemic flow ratio in 33 patients undergoing cardiac catheterization (systemic flow [n = 28], r = 0.78; pulmonary flow [n = 21], r = 0.88; Qp/Qs ratio [n = 24], r = 0.85). The random errors of the 2 methods were not significantly different. Outflow tract obstruction, semilunar valve regurgitation, and patent ductus arteriosus were the only lesions in which limitations to the use of this method were encountered. We anticipate that this method will be of use in initial and serial evaluations of adult and pediatric patients with low cardiac output or intracardiac shunts.     

Use of the indirect axillary pulse tracing for noninvasive determination of ejection time, upstroke time, and left ventricular wall stress throughout ejection in infants and young children

The use of indirect axillary pulse tracings was investigated as an alternative method to record the carotid pulse in infants and young children. Simultaneous high-speed recordings of ascending aortic pressure and indirect axillary pulse tracings with noninvasive peripheral blood pressures were recorded in 30 young children (aged 1 day to 48 months, median 9 months) during cardiac catheterization. In 15 patients, simultaneous left ventricular (LV) M-mode echocardiograms and phonocardiograms were also performed. Systolic ejection time (SET) and the half-time of the pulse upstroke determined by both methods were compared. Computer analysis of digitized echocardiographic and pulse tracing data was used to generate plots of LV wall stress throughout ejection. Values for wall stress derived from calibrated indirect axillary pulse tracings were compared with those derived from central aortic pressure. SET calculated from axillary tracings was within 5% of the aortic value in 91% of cases, with a mean error for all subjects of -1 +/- 3%. The half-time of the pulse upstroke was within 15% of the aortic value in 91% of cases, with a mean error for all subjects of 6 +/- 12%. LV wall stress was compared at the onset of ejection, peak wall stress, midsystole, and endsystole for each patient, and 98% of values calculated from axillary data were within 10% of the wall stress values calculated from aortic pressure measurements. Thus, indirect axillary pulse tracings provide an excellent representation of the aortic pressure contour and can be used for accurate calculation of SET.(ABSTRACT TRUNCATED AT 250 WORDS)     

Noninvasive determination of systolic,diastolic and end-systolic blood pressure in neonates,infants and young children: Comparison with central aortic pressure measurements

Noninvasive determinations of systolic and diastolic blood pressure using the oscillometric method for pressure measurement were combined with externally recorded axillary pulse tracings to estimate end-systolic pressure in 32 neonates, infants and young children. Results were compared with central aortic pressure measurements made at the time of central aortic catheter placement. Studies were performed in patients aged 1 day to 48 months who weighed 0.9 to 18.1 kg. A wide range of systolic (41 to 141 mm Hg), diastolic (22 to 73 mm Hg) and end-systolic (30 to 111 mm Hg) pressure values were found. The mean absolute pressure differences and percent errors (pressure difference divided by central aortic pressure) were 1.8 mm Hg and 2.5% for systolic, 0.8 mm Hg and 0.8% for diastolic and 1.4 mm Hg and 2.1% for end-systolic pressure. No correlation was noted between percent error and age, weight, heart rate, cardiac index or systemic vascular resistance. The ability to perform reliable noninvasive pressure measurements should prove invaluable for clinical and research purposes. In addition, this method of end-systolic blood pressure determination enables sensitive indexes of left ventricular contractility to be measured noninvasively in small children.     

Lung biopsy with frozen section as a diagnostic aid in patients with congenital heart defects

In eight patients with congenital heart defects and equivocal preoperative hemodynamic data, lung biopsy with frozen section was performed and quantitative morphometric analysis carried out to help select a palliative or corrective surgical procedure. During catheterization it had been possible in only six of the eight patients to enter the pulmonary artery and obtain pressure measurements; four patients had moderate to severe elevation of pulmonary vascular resistance whereas the other two had only mild elevation of pulmonary arterial pressure, but they were being considered for a Fontan procedure.The lung biopsy tissue was taken inflated and fixed inflated in hot glutaraldehyde. From cryostat sections arterial concentration was assessed relative to alveolar concentration, and the degree of arterial muscularity was assessed by wall thickness and extension of muscle; the more advanced Heath-Edwards arterial changes were also evaluated. On the basis of the morphologic assessment, six of the eight patients underwent corrective surgery and two underwent a palliative procedure. Postoperative hemodynamic data available in four of the patients who underwent corrective surgery revealed either a significant reduction in pulmonary vascular resistance or return to a normal level of pulmonary arterial pressure, whereas no change has occurred in the one patient studied who underwent a palliative procedure. Assessment of pulmonary arterial development and structure on lung biopsy with frozen section proved helpful in deciding between a palliative and corrective surgical procedure.     

Congenital pulmonary vein stenosis: structural changes in a patient with normal pulmonary artery wedge pressure

A male infant is described who died at 13 months of age with stenosis of all extrapulmonary veins except the left upper vein. The pulmonary artery wedge pressure was normal, the first time this is reported in this condition. At autopsy, there were structural changes of the pulmonary arteries and veins in all lobes with or without pulmonary vein stenosis. Arterial changes-muscle extension, medial hypertrophy and decreased arterial size--analyzed quantitatively were found to be similar in all lobes. Venous medial hypertrophy was more marked in obstructed lobes. These anatomic changes are presumably due to fixed venous obstruction in the pulmonary lobes drained by stenotic veins and to high flow in the left upper lobe.     

Relation of the echocardiographic estimate of left ventricular size to mortality in infants with severe left ventricular outflow obstruction

The relation of left ventricular size, as estimated with echocardiography, to mortality was evaluated in three groups of infants with severe left ventricular outflow obstruction. Group I consisted of 17 patients with combined aortic and mitral stenosis or atresia associated with definite hypoplasia of the left ventricle. Group II consisted of eight patients with the primary diagnosis of severe aortic stenosis. Group III consisted of 12 patients with severe coarctation of the aorta. The left ventricular enddiastolic dimension measured with M mode echocardiography and the cross-sectional area of the left ventricular cavity as seen in the parasternal long axis view of the two dimensional echocardiogram were used as indexes of left ventricular volume.All patients with symptomatic outflow obstruction and a left ventricular end-diastolic dimension of less than 13 mm died in infancy. However, five patients with a hypoplastic left ventricle proved at angiography or at autopsy, or both, were found to have a ventricular end-diastolic dimension of 13 mm or greater. Two dimensional echocardiography showed that the left ventricle in these patients was foreshortened and spherical in shape. The cross-sectional area of the left ventricle of each patient in group I was less than 1.6 cm². This was below the range of cross-sectional areas found in a group of normal infants (1.8 to 3.5 cm² ± 2 standard deviations about the mean). Three patients in groups II and III had a slightly reduced left ventricular area (1.7 cm²) and none of these patients survived infancy.Measurement of the cross-sectional area of the left ventricle is a useful method of determining left ventricular size in infants suspected of having the hypoplastic left ventricle syndrome. Patients who have reduced left ventricular volume as assessed by this technique are at very great risk even if surgical relief of the outflow obstruction is attempted.     

Fixed subaortic stenosis in the young: Medical and surgical course in 83 patients

Eighty-three patients aged 11 months to 25 years were followed up a median of 6.1 years (range 8 days to 24 years) after diagnosis of fixed subaortic stenosis (SAS). Fourteen (17%) had significant noncardiac defects and 47 (57%) had additional cardiac malformations. The left ventricular (LV) outflow gradient increased in 25 of 26 patients catheterized more than once before surgery. Of 15 patients < 12 years old with gradients < 40 mm Hg, 10 ultimately underwent operation after developing severe obstruction; another has progressed to a gradient of 45 mm Hg at 6 years of age. Before surgery (at a median age of 12 years), 55% had aortic regurgitation (AR), which was usually mild. Infective endocarditis occurred in 12% of the group, with a frequency of 14.3 cases per 1,000 patientyears. Seventy-four patients were operated on, with 6 early (8%) and 7 late (9%) deaths. Twelve underwent reoperation to relieve residual obstruction. Surgery reduced gradients in patients with discrete SAS from 83 ± 33 to 29 ± 30 mm Hg, but in 6 patients with tunnel SAS the reduction was less satisfactory. AR was absent or mild in most patients postoperatively. When the gradient was reduced to < 80 mm Hg, infective endocarditis did not occur unless there were other residual lesions. These data suggest that it is reasonable to resect discrete SAS in children < 10 to 12 years old with LV outflow gradients ?- 30 mm Hg.