Reliability of multicenter pediatric echocardiographic measurements of left ventricular structure and function: the prospective P(2)C(2) HIV study.

BACKGROUND: To assess the reliability of pediatric echocardiographic measurements, we compared local measurements with those made at a central facility. METHODS AND RESULTS: The comparison was based on the first echocardiographic recording obtained on 735 children of HIV-infected mothers at 10 clinical sites focusing on measurements of left ventricular (LV) dimension, wall thicknesses, and fractional shortening. The recordings were measured locally and then remeasured at a central facility. The highest agreement expressed as an intraclass correlation coefficient (ICC=0.97) was noted for LV dimension, with much lower agreement for posterior wall thickness (ICC=0.65), fractional shortening (ICC=0.64), and septal wall thickness (ICC=0.50). The mean dimension was 0.03 cm smaller in central measurements (95% prediction interval [PI], -0.32 to 0.25 cm) for which 95% PI reflects the magnitude of differences between local and central measurements. Mean posterior wall thickness was 0.02 cm larger in central measurements (95% PI, -0.18 to 0.22 cm). Mean fractional shortening was 1% smaller in central measurements. However, the 95% PI was -10% to 8%, indicating that a fractional shortening of 32% measured centrally could be anywhere between 22% and 40% when measured locally. Central measurements of mean septal thickness were approximately 0.1 cm thicker than local ones (95% PI, -0.18 to 0.34 cm). Centrally measured wall thickness was more closely related to mortality and possibly was more valid than local measurements. CONCLUSIONS: Although LV dimension was reliably measured, local measurements of LV wall thickness and fractional shortening differed from central measurements.

Cardiac dysfunction and mortality in HIV-infected children: The Prospective P2C2 HIV Multicenter Study. Pediatric Pulmonary and Cardiac Complications of Vertically Transmitted HIV Infection (P2C2 HIV) Study Group.

BACKGROUND: Left ventricular (LV) dysfunction is common in children infected with the human immunodeficiency virus (HIV), but its clinical importance is unclear. Our objective was to determine whether abnormalities of LV structure and function independently predict all-cause mortality in HIV-infected children. METHODS AND RESULTS: Baseline echocardiograms were obtained on 193 children with vertically transmitted HIV infection (median age, 2.1 years). Children were followed up for a median of 5 years. Cox regression was used to identify measures of LV structure and function predictive of mortality after adjustment for other important demographic and baseline clinical risk factors. The time course of cardiac variables before mortality was also examined. The 5-year cumulative survival was 64%. Mortality was higher in children who, at baseline, had depressed LV fractional shortening (FS) or contractility; increased LV dimension, thickness, mass, or wall stress; or increased heart rate or blood pressure (P0.02 for each). Decreased LV FS (P<0.001) and increased wall thickness (P=0.004) were also predictive of increased mortality after adjustment for CD4 count (P<0.001), clinical center (P<0.001), and encephalopathy (P<0.001). FS showed abnormalities for up to 3 years before death, whereas wall thickness identified a population at risk only 18 to 24 months before death. CONCLUSIONS: Depressed LV FS and increased wall thickness are risk factors for mortality in HIV-infected children independent of depressed CD4 cell count and neurological disease. FS may be useful as a long-term predictor and wall thickness as a short-term predictor of mortality.

Relationship between cumulative anthracycline dose and late cardiotoxicity in childhood acute lymphoblastic leukemia.

PURPOSE: Late anthrocycline cardiotoxicity after treatment for childhood cancer is common and often progressive. A safe anthracycline dose that will not result in late cardiac abnormalities has not been established due to the limited dose ranges used in existing studies. PATIENTS AND METHODS: To determine the relationship between cumulative anthracycline dose and late cardiotoxicity, we performed echocardiograms on 189 survivors of childhood acute lymphoblastic leukemia a median of 8.1 years (range, 2.0 to 23.4) after completion of anthracycline therapy. Patients were treated according to protocols that used widely varying cumulative anthracycline doses, but comparable nonanthracycline chemotherapy. Patients were divided into four groups based on the city of treatment and cumulative anthracycline dose: Copenhagen, 0 to 23 mg/m2 (n = 32); Boston, 45 mg/m2 (n = 17); Copenhagen, 73 to 301 mg/m2 (n = 53); and Boston, 244 to 550 mg/m2 (n = 87). Left ventricular dimension and fractional shortening were adjusted for sex and age or body-surface area through use of a control population (n = 296), and then compared among the four groups. RESULTS: Mean left ventricular dimension was significantly increased in the high-dose Boston group (observed:predicted value, 4.57 cm:4.45 cm; P = .002) and significantly higher than in the two Copenhagen groups. In the three lower-dose groups, there was no significant increase in mean left ventricular dimension, and the groups were not significantly different from each other. Similarly, the mean left ventricular fractional shortening was significantly depressed in the high-dose Boston group (observed:predicted value, 29.0%:33.8%; P = .0001) and significantly lower than in the three lower-dose groups. CONCLUSION: Depressed left ventricular fractional shortening and left ventricular dilatation were uncommon years after treatment of childhood leukemia when cumulative anthracycline doses were < or = 300 mg/m2.

Two-dimensional echocardiographic evaluation of right ventricular size and function in newborns with severe right ventricular outflow tract obstruction.

Critical pulmonary stenosis or atresia with intact ventricular septum represents a congenital cardiac lesion for which the long-term prognosis appears to depend partly on the size of the right ventricle. Thus, the capability of noninvasive assessment of right ventricular size to predict operative outcome was examined in 15 infants (aged 1 to 30 days, mean 5.6) with severe right ventricular outflow tract obstruction (either critical pulmonary stenosis [7 patients] or pulmonary atresia with intact ventricular septum [8 patients]). Using echocardiography in two orthogonal subxiphoid views, right ventricular volume, wall thickness, area change fraction, ejection fraction and tricuspid anulus dimension were measured. All patients with a normalized right ventricular enddiastolic volume of less than 5 ml/m2 and a normalized tricuspid anulus dimension of less than 1.0 cm/m2/3 required a shunt operation. Only one patient with a volume of more than 6 ml/m2 and a normalized tricuspid anulus dimension of more than 1.4 cm/m2/3 required more than relief of right ventricular outflow tract obstruction. In this patient, residual severe pulmonary stenosis necessitated the shunt procedure. One patient with a volume of more than 6 ml/m2 had an anulus diameter of less than 1.4 cm/m2/3 and one patient with an anulus diameter of more than 1.4 cm/m2/3 had a volume of less than 6 ml/m2; both required shunt procedures. It therefore appears that if either the ventricular volume or tricuspid anulus size is excessively small, a shunt procedure is necessary. Wall thickness, area change fraction and ejection fraction measurements were not significantly correlated with right ventricular volume or postoperative outcome.(ABSTRACT TRUNCATED AT 250 WORDS)

Left ventricular end-systolic wall stress-velocity of fiber shortening relation: a load-independent index of myocardial contractility.

The velocity of circumferential fiber shortening (Vcf) is an index of myocardial performance which, although sensitive to contractile state, has limited usefulness because of its dependence on left ventricular loading conditions. This study investigated the degree and velocity of left ventricular fiber shortening as it relates to wall stress in an attempt to develop an index of contractility that is independent of preload and heart rate while incorporating afterload. Studies were performed in 78 normal subjects using M-mode echocardiography, phonocardiography and indirect carotid pulse tracings under baseline conditions. In addition, studies were performed on 25 subjects during afterload augmentation with methoxamine, 8 subjects before and during afterload challenge after increased preload with dextran and 7 subjects with enhanced left ventricular contractility with dobutamine. The relation of end-systolic stress to the velocity of fiber shortening and to the rate-corrected velocity of shortening (corrected by normalization to an RR interval of 1) was inversely linear with correlation coefficients of -0.72 and -0.84, respectively. Alterations in afterload, preload or a combination of the two did not significantly affect the end-systolic wall stress/rate-corrected velocity of shortening relation, whereas during inotropic stimulation, the values were higher, with 94% of the data points above the normal range. Age did not appear to affect the range of normal values for this index. In contrast, the end-systolic wall stress/fractional shortening relation was not independent of preload status, responding in a manner similar to that seen with a positive inotropic intervention. Thus, the velocity of circumferential fiber shortening normalized for heart rate is inversely related to end-systolic wall stress in a linear fashion. Accurate quantitation can be performed by noninvasive means and a range of normal values determined. This index is a sensitive measure of contractile state that is independent of preload, normalized for heart rate and incorporates afterload. In contrast, the end-systolic wall stress/fractional shortening relation is dependent on end-diastolic fiber length in the range of physiologically relevant changes in preload.

Obstruction of right ventricular inflow and outflow in corrected transposition of the great arteries (S,L,L): two-dimensional echocardiographic diagnosis.

Obstruction of systemic ventricular inflow and outflow is considered uncommon in corrected transposition of the great arteries (S,L,L). Between 1979 and 1985, 42 patients with corrected transposition and two ventricles and atrioventricular valves underwent two-dimensional echocardiography. Obstruction of right ventricular inflow and outflow was present and diagnosed by two-dimensional echocardiography in 5 of the 42 patients. A supratricuspid stenosing ring, recognized in the apical or subxiphoid four chamber view as a bright, linear structure on the left atrial side of the tricuspid valve, occurred in two patients. Subaortic obstruction due to infundibular hypertrophy with or without displaced muscle bundles was seen in three patients. Subxiphoid long- and short-axis views and parasternal long-axis views best displayed these features. Aortic coarctation was present in four cases and could be diagnosed using modified suprasternal notch views. Thus, systemic ventricular inflow and outflow obstruction may be more common in corrected transposition than previously believed (occurring in up to 10 to 15% of patients). The mechanisms producing the obstruction appear to be characteristic of the left atrium and right ventricle irrespective of location or connections. Echocardiography appears to be an excellent technique for diagnosing these associated lesions in corrected transposition.

Physiologic hypertrophy: effects on left ventricular systolic mechanics in athletes.

Physiologic hypertrophy resulting from intense athletic participation has been reported to result in normal, reduced and augmented overall left ventricular performance. Rather than representing true differences in left ventricular contractility, these data may reflect the variable degree of ventricular dilation and increased wall thickness that occur with different types of exercise. As such, the resultant altered loading conditions may diminish the ability of the usual indexes of left ventricular function to accurately assess the left ventricular contractile state. Therefore, three groups of elite athletes with distinct patterns of myocardial hypertrophy were investigated utilizing recently developed load-independent contractility indexes. Age-matched control subjects (n = 33) were compared with 11 swimmers, 11 long-distance runners and 11 power lifters. Rest echocardiogram, phonocardiogram and calibrated carotid pulse tracing were used to calculate left ventricular dimensions, wall thickness, mass, fractional shortening, velocity of shortening and mean, peak and end-systolic wall stresses and the stress-time and minute stress-time integrals. Compared with control subjects, all athletes had increased left ventricular mass, even when values were normalized for body surface area. Runners had a dilated left ventricular and normal wall thickness, swimmers had a mildly dilated ventricle with increased wall thickness and power lifters had normal cavity size with markedly increased wall thickness. Peak systolic wall stress was normal in runners and swimmers and reduced in power lifters, whereas end-systolic stress was low in swimmers and power lifters and normal in runners. The minute stress-time integral, a measure of myocardial oxygen consumption, was normal in runners and swimmers but was significantly reduced in lifters.(ABSTRACT TRUNCATED AT 250 WORDS)

Developmental modulation of myocardial mechanics: age- and growth-related alterations in afterload and contractility.

Somatic growth is associated with alterations in myocardial mechanics in children with heart disease and in most animal models of congenital heart disease. However, the effect of age and body size on myocardial contractility and loading conditions in normal infants and children is not known. Therefore, 256 normal children aged 7 days to 19 years (34% less than 3 years old) were evaluated with noninvasive indexes of left ventricular contractility and loading conditions. Two-dimensional and M-mode echocardiographic recordings of the left ventricle were obtained with a phonocardiogram, indirect pulse tracing and blood pressure recordings. Left ventricular dimensions, wall thickness and pressure measurements obtained from these data were used to calculate peak and end-systolic circumferential and meridional wall stress and mean and integrated meridional wall stress. Velocity of shortening adjusted for heart rate was compared with end-systolic stress to assess contractility independently of loading status. The subjects were stratified for gender and each of the derived variables was related to age and body surface area. Ventricular shape, assessed as the major/minor axis ratio, and the circumferential/meridional stress ratio were found to be invariant with growth. The ratio of posterior wall thickness to minor axis dimension did not change with age, despite the normal age-related increase in blood pressure. The increase in pressure despite unvarying ventricular shape and wall thickness/dimension ratio resulted in a substantial increase in wall stress that was most dramatic during the first few years of life. In association with the increase in afterload, systolic function decreased with age. However, the age-related decrease in the velocity of shortening was greater than that expected from the increase in afterload alone, indicating a higher level of contractility in infants and children during the first years of life than in older subjects. The process of normal growth and development, similar to that in children with heart disease, is associated with a rapid decrease in the trophic response to hemodynamic loads, resulting in an age-associated increase in wall stress. There is a similar but somewhat more rapid decrease in contractility, with the highest values seen in the youngest patients.

Left ventricular mechanics and contractile state in children and young adults with end-stage renal disease: effect of dialysis and renal transplantation.

The potential existence of a specific uremia-associated myocardial depressant factor was explored by evaluating nine pediatric subjects (3 to 21 years) without evidence of coronary artery disease or long-standing hypertension 1) before entering a dialysis program, 2) while undergoing a long-term dialysis regimen, and 3) after successful renal transplantation. Myocardial contractility was quantitated with load-independent indexes using the end-systolic pressure-dimension relation (Emax) and the relation of rate-corrected velocity of shortening to end-systolic wall stress. Myocardial loading status was determined by the direct measurement of afterload (end-systolic wall stress) and the functional quantitation of preload (differences between the relation of fractional shortening and velocity of shortening to end-systolic stress). Most patients (55%) were found to have abnormal ejection phase indexes of ventricular function either before or after entry into dialysis. However, contractility was normal in all subjects at each of their evaluations, and no change in contractility was found after dialysis or transplantation. Loading status was highly variable and usually abnormal before transplantation and accounted entirely for the abnormalities of fractional shortening and velocity of shortening. Transplantation invariably resulted in normalization of loading status and ejection phase indexes of ventricular function. In these children and young adults with uremia, abnormal ejection phase indexes of ventricular function were frequent and caused by associated abnormalities in ventricular loading. Contractility, however, was normal and no evidence of a uremia-associated myocardial depressant was found.

Noninvasive estimation of the left ventricular pressure waveform throughout ejection in young patients with aortic stenosis.

Validation of a totally noninvasive method for estimating instantaneous left ventricular pressure and constructing a pressure waveform throughout ejection in patients with aortic stenosis is reported. In 20 patients (aged 8.75 +/- 10 years) with congenital aortic stenosis (measured peak left ventricular pressure 120 to 260 mm Hg; transvalvular gradient 18 to 165 mm Hg), transaortic valve continuous wave Doppler ultrasound, indirect carotid pulse tracing, peripheral blood pressure and measured left ventricular pressure were recorded simultaneously at cardiac catheterization. Data were entered into a microcomputer using a digitizing tablet and the instantaneous Doppler gradient was calculated and added to instantaneous aortic pressure, derived from the time-corrected and calibrated carotid pulse tracing, to estimate instantaneous left ventricular pressure. Estimated left ventricular pressure waveforms reproduced measured left ventricular pressure closely. The mean error at peak left ventricular pressure was 0.2 +/- 4.8 mm Hg (r = 0.98, p = 0.001). The average error throughout ejection was 0.9 +/- 5.1 mm Hg. The error of estimated pressure was not related to age or the severity of aortic stenosis. The Doppler peak instantaneous gradient was observed to correlate closely (r = 0.97, p = 0.001) with peak to peak gradient. With this technique, the left ventricular pressure waveform throughout ejection can be accurately estimated noninvasively in patients with aortic stenosis. This methodology enables determination of mean, total and instantaneous systolic left ventricular pressure.

Recognition of abnormal connections of coronary arteries with the use of Doppler color flow mapping.

Anomalous connection of a coronary artery to a ventricle or pulmonary artery causes shunting of blood from the coronary circuit and may produce myocardial ischemia. Such a coronary anomaly may occur in isolation or with other defects. Doppler color flow mapping and two-dimensional echocardiography were used to diagnose anomalous coronary connections in 13 patients, 1 day to 7 years of age, over a 1 year period. The diagnoses were anomalous origin of the left coronary artery from the pulmonary trunk in five patients, a coronary artery to left ventricle fistula or coronary artery to pulmonary artery fistula in four patients with other complex defects, right ventricular sinusoids in two patients with pulmonary atresia and intact ventricular septum and an isolated coronary artery fistula in two patients. In all cases, the abnormal coronary connection was recognized on the basis of an abnormal, continuous or to and fro flow pattern in the fistula and its connections as demonstrated by scanning in multiple views with Doppler color flow mapping. The low spatial resolution of Doppler color flow mapping limits the anatomic detail available; nonetheless, it is a significant advance in the noninvasive diagnosis of abnormal coronary connections.

Anomalous origin of left coronary artery from pulmonary artery: recovery of left ventricular function after dual coronary repair.

OBJECTIVES: We reviewed our institutional experience with anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) after dual coronary repair to assess preoperative variables predictive of outcome, the time course for postoperative recovery of cardiac function, the short- and long-term complications and our experience with left ventricular assist devices (LVAD) in these patients. BACKGROUND: Outcome after surgical repair of ALCAPA remains incompletely defined. METHODS: The surgical records and echocardiograms of 42 patients were reviewed. Left ventricular function was assessed by fractional shortening z-score (FSz) and stress-velocity index. RESULTS: The overall survival rate was 86%. All six patients who died were < 1 year old and died within 3 days of the operation. More severe preoperative mitral regurgitation (MR) was associated with increased mortality, but age, body surface area, preoperative FSz and end-diastolic dimension were not. We used an LVAD for 7 of 28 patients who underwent repair for ALCAPA since its introduction at our institution, with a survival of 5 of 7 patients. The degree of MR improved in 62% of patients and remained unchanged in 38%. Complications included supravalvar pulmonary stenosis (16 of 21 patients) and baffle leaks (11 of 21 patients) with the intrapulmonary baffling technique. Supravalvar pulmonary stenosis developed in 1 of 11 patients after direct coronary reimplantation. Left ventricular function became normalized in all 28 patients with follow-up past 1 year, regardless of preoperative FSz. Of 13 patients who underwent serial postoperative echocardiography, the average time to normalization of function was 2 to 7 months. CONCLUSIONS: The degree of preoperative MR was predictive of outcome, whereas the severity of preoperative cardiac dysfunction and ventricular dilation were not. Mild and moderate MR tended to improve without mitral valvuloplasty. Complete recovery from myocardial dysfunction is expected after dual coronary repair of ALCAPA.

Early diastolic left ventricular function in children and adults with aortic stenosis.

Pressure overload hypertrophy of the left ventricle is associated with abnormal left ventricular early diastolic filling. The roles of the extent of cardiac hypertrophy, depressed left ventricular systolic function and aging in the pathogenesis of left ventricular diastolic dysfunction have not, however, been fully defined. To determine the relative importance of these factors in the pathogenesis of diastolic dysfunction in pressure overload hypertrophy, 16 children and 25 adults with aortic stenosis were compared with 48 normal children and adults, using rates of left ventricular early diastolic filling and wall thinning derived from M-mode echocardiography. Left ventricular early diastolic filling and wall thinning rates were significantly depressed in both children and adults with aortic stenosis as compared with values in normal subjects. Filling and thinning rates correlated negatively with age, left ventricular peak systolic pressure and wall thickness in all subjects. Furthermore, the effect of age on diastolic function appeared to be mediated by age-related increases in systolic pressure and wall thickness. In adults with aortic stenosis, early diastolic filling and wall thinning rates were depressed to a similar extent in subjects with normal and abnormal systolic function; thus, diastolic dysfunction does not appear to be a manifestation of abnormal systolic loading and ejection performance. These results suggest that extent of hypertrophy itself plays a dominant role in the mechanism of impaired left ventricular early diastolic filling in pressure overload due to aortic stenosis.

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.

Are routine preoperative cardiac catheterization and angiography necessary before repair of ostium primum atrial septal defect?

Two-dimensional and Doppler echocardiography were compared with cardiac catheterization and angiography in the preoperative evaluation of ostium primum atrial septal defect. Preoperative echocardiographic examinations as well as operative reports of all patients (33 patients aged 2 months to 23 years at surgery) with ostium primum atrial septal defect or transitional atrioventricular (AV) canal defect having had echocardiography and surgical repair at The Children's Hospital, Boston from July 1983 to January 1986 were retrospectively reviewed. Original cardiac catheterization and angiographic reports also were reviewed. Preoperative echocardiography resulted in no false positive or false negative primary diagnoses when compared with the diagnoses obtained at preoperative angiography or surgery. Doppler assessment of mitral regurgitation correlated well with angiographic (93% agreement) and intraoperative (85% agreement) assessments of mitral regurgitation to within two diagnostic categories on the six level scoring system used. There was reasonably good agreement between the two-dimensional echocardiographic estimate of right ventricular systolic pressure and that measured at catheterization when expressed as percent of the simultaneous left ventricular pressure. Seven of nine ventricular septal defects observed intraoperatively were noted on preoperative echocardiography; five of these defects were detected on preoperative angiography. A variety of other surgically confirmed associated cardiovascular defects were observed by both preoperative techniques. However, echocardiography appeared to be superior to angiography for evaluation of AV valve morphology and papillary muscle architecture. This study implies that in children with typical clinical and two-dimensional echocardiographic and Doppler findings for ostium primum atrial septal defect or transitional AV canal defect, routine preoperative cardiac catheterization and angiography are unnecessary.

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.

Echocardiographic predictors of left ventricular outflow tract obstruction after repair of interrupted aortic arch.

OBJECTIVES: This study was designed to identify preoperative echocardiographic predictors of left ventricular outflow tract obstruction after repair of interrupted aortic arch and ventricular septal defect closure. BACKGROUND: Left ventricular outflow tract obstruction becomes apparent in nearly 50% of patients after repair of interrupted aortic arch and ventricular septal defect closure but is seldom recognized preoperatively. METHODS: We analyzed the preoperative echocardiograms of all patients with interrupted aortic arch who had postoperative echocardiographic or catheterization data available. Thirty-seven infants (aged 1 day to 10 months, median 5 days) were included. Off-line measurements were performed on hard copies of selected images. The cross-sectional area (indexed to body surface area) and diameters (indexed to the square root of body surface area) of the left ventricular outflow tract; ascending and descending aorta; ventricular septal defect; and mitral, aortic and pulmonary valves were compared with outcome by using analysis of variance. Outcome was classified according to development of postoperative left ventricular outflow tract Doppler gradient (Group 1 < or = 20 mm Hg, Group 2 > 20 mm Hg). RESULTS: The cross-sectional area of the left ventricular outflow tract was significantly smaller in patients who did than in those who did not develop subaortic obstruction ([mean +/- SD] 0.64 +/- 0.25 vs. 1.7 +/- 1.01 cm2/m2, p < 0.004). Left ventricular outflow tract and aortic valve diameters and aortic valve area were not predictive of postoperative left ventricular outflow tract obstruction. Incidence of postoperative left ventricular outflow tract obstruction was lower (p < 0.03) in interrupted aortic arch type A (0 of 6) than in type B (15 of 31). The incidence of aberrant right subclavian artery was lower (p < 0.02) in Group 1 (6 of 22) than in Group 2 (10 of 15). CONCLUSIONS: The preoperatively measured cross-sectional area of the left ventricular outflow tract is significantly smaller in patients with interrupted aortic arch who develop subaortic obstruction postoperatively, with a left ventricular outflow tract area < or = 0.7 cm2/m2 being a sensitive predictor. Aortic arch anatomy (i.e., type of interrupted aortic arch and presence of aberrant right subclavian artery) is also predictive of postoperative left ventricular outflow tract obstruction, possibly by influencing the volume of blood flow across the left ventricular outflow tract. These data should enable preoperative identification of infants who may require surgical relief of subaortic stenosis.

Effect of young age on coronary adaptations to left ventricular pressure overload hypertrophy in sheep.

OBJECTIVES: This study attempted to determine the effect of young age on changes in coronary conductance and capillary density with left ventricular pressure overload hypertrophy. Mechanisms responsible for age differences in perfusion capacity were examined. BACKGROUND: Hypertension in adults causes alterations in the coronary vasculature, resulting in diminished coronary perfusion capacity and myocardial ischemia. These processes are worsened in adults by advanced age. Young age may provide advantages in coronary adaptation to hypertension. METHODS: Coronary conductance was examined in conscious chronically instrumented 10-week old lambs and adult sheep with progressive ascending aortic stenosis of 6-week's duration and age-matched control sheep by means of the microsphere technique and vasodilators. Capillary density was measured post-mortem. RESULTS: Adult sheep with aortic stenosis had a decrease in left ventricular subendomyocardial capillary density by 17% and maximal coronary conductance with adenosine by 67%. In the nonhypertrophied right ventricle, maximal coronary conductance was depressed by 47%, whereas capillary density was normal, implying an effect of coronary hypertension on resistance vessels. In contrast, lambs with aortic stenosis maintained normal left ventricular capillary density, maximal coronary conductance and coronary reserve and had relatively little impairment of conductance in the right ventricular coronary bed (-15%, p = NS). Similar responses were found with other vasodilators, isoproterenol and chromonar. CONCLUSIONS: Young age confers advantages to coronary adaptation to left ventricular pressure overload, including angiogenesis proportionate to hypertrophy, resulting in normal capillary density and coronary conductance. There is also less hypertension-induced impairment of coronary conductance distinct from the effects of hypertrophy.

Left ventricular mechanics during and after acute rheumatic fever: contractile dysfunction is closely related to valve regurgitation.

OBJECTIVES: The purpose of this study was to characterize left ventricular (LV) mechanics during acute rheumatic fever (ARF) and to define factors influencing remodeling after the acute event. BACKGROUND: Acute rheumatic fever is associated with varying degrees of valvulitis and myocarditis, but the impact of these factors on LV mechanics is poorly defined. METHODS: Echocardiograms and clinical data were reviewed in 55 patients aged 11.2 +/- 2.6 years during ARF. Valve regurgitation was absent or mild in 33 (group I) and moderate or severe in 22 (group II). Forty-two children (75%) underwent a further examination after ARF. RESULTS: Group I patients demonstrated a mildly elevated LV size during ARF and had normal indexes at follow-up. Group II patients demonstrated a markedly elevated LV size (end-diastolic dimension z-score 3.6 +/- 1.8, p < 0.01 compared with the normal population) and decreased shortening fraction (z-score -0.8 +/- 1.4, p < 0.05). The stress-velocity index, a z-score describing the velocity of shortening-afterload relationship, was normal in group II patients with mitral regurgitation (-0.2 +/- 1.2, p = NS) but was depressed in those with aortic regurgitation or both (- 1.4 +/- 1.4, p < 0.01). At follow-up the stress-velocity index remained depressed (-1.2 +/- 1.0, p < 0.01) and had deteriorated in those treated nonsurgically compared with those treated surgically (interval change nonsurgical -0.7 +/- 1.2 vs. surgical 1.3 +/- 1.3, p = 0.005). CONCLUSIONS: The evolution of contractile dysfunction during and after ARF is dependent on the degree and type of valve regurgitation and may be influenced by surgical intervention. These findings suggest that mechanical factors are the most important contributors to myocardial damage during and after ARF.

Double-inlet single left ventricle: echocardiographic anatomy with emphasis on the morphology of the atrioventricular valves and ventricular septal defect.

The echocardiographic anatomy of double-inlet single left ventricle was studied in 57 patients, aged 1 day to 27 years (mean 6 years); the variables examined included morphology, size and function of the atrioventricular (AV) valves and ventricular septal defect and their relation to pulmonary stenosis, aortic stenosis and aortic arch obstruction. The visceroatrial situs was solitus and the heart was in the left side of the chest in all 57 patients. A d-loop ventricle was present in 21 patients and an l-loop ventricle in 36. The great arteries were normally related (Holmes heart) in 8 patients and transposed in 49. In all hearts, the right AV valve was anterior to the left AV valve. In 53 patients, the tricuspid valve (right valve in d-loop and left valve in l-loop) was closer to and had attachments on the septum. The tricuspid valve straddled the outflow chamber in eight patients. No significant difference was noted in the mean AV valve diameter when comparing mitral and tricuspid valves within the same group or between the groups with a d- or l-loop ventricle. The right AV valve diameter had a significant direct correlation with the aortic valve diameter and the size of the ventricular septal defect regardless of ventricular loop. Both AV valves were functionally normal in 34 patients. Among patients with AV valve dysfunction, the tricuspid valve tended to be stenotic in patients with an l-loop ventricle and regurgitant in patients with a d-loop ventricle. Mitral valve dysfunction was uncommon. The ventricular septal defect (46 patients) was separated from the semilunar valves in 24 patients (muscular defect) and adjacent to the anterior semilunar valve as a result of hypoplasia or malalignment, or both, of the infundibular septum (subaortic defect) in 19 patients. Multiple defects were present in three patients. The defect was unrestrictive in 26 patients, restrictive in 23 and could not be evaluated in 8. Pulmonary artery banding had been performed in 8 of the 26 patients with an unrestrictive defect and in 10 of the 23 patients with a restrictive defect. Only 4 of 19 subaortic defects compared with 16 of 24 muscular defects were restrictive. The size of the defect was significantly correlated with the measured pressure gradient. Among patients with transposition, only 2 of 13 with pulmonary stenosis had a restrictive ventricular septal defect compared with 15 of 30 without pulmonary stenosis. In patients with transposition, the defect size was significantly smaller when coarctation was present.