Faculty Bibliography

PURPOSE: Congenital aortic valve stenosis is a common problem in pediatric cardiology. The catheter peak to peak systolic gradient is the accepted standard used for prognosis and intervention, but noninvasive correlation in pediatric patients is frequently associated with underestimation or overestimation of this gradient. The purpose of this study was to compare different noninvasive measurements with simultaneous catheter gradients to identify which best predicts the catheter peak to peak gradient. METHODS: Twenty-five simultaneous Doppler and catheter measurements of aortic stenosis gradient were performed in 14 children (all 14 before valvuloplasty and 11 after valvuloplasty). Noninvasive estimates of pressure gradient were compared with catheter measurements with linear regression and Bland-Altman analysis. RESULTS: The Doppler peak instantaneous pressure gradient overestimated the catheter peak to peak gradient but correlated well with the catheter peak instantaneous gradient. The Doppler mean systolic gradient correlated well with the catheter peak to peak gradient at low gradients and underestimated higher catheter gradients but agreed well at all levels with the catheter mean gradient. The modification of a catheter-derived correlation equation produced good correlation with the catheter peak to peak gradient (slope, 1.14; intercept, -1.8; R, 0.92), as did the use of estimated pressure recovery (slope, 1.04; intercept, 5.0; R, 0.94), calculated from a defined fluid mechanic equation. CONCLUSION: The catheter peak to peak gradient can be accurately estimated noninvasively using estimated pressure recovery or correlation equations incorporating Doppler measurements

Hypoplastic left heart syndrome (HLHS) with a restrictive atrial septal defect (ASD) is a form of congenital heart disease with considerable morbidity and mortality. This morphologic analysis assesses the pulmonary vasculature in this patient population. Pulmonary arteries, the persistence of high-resistance fetal arterioles, pulmonary veins, and lymphatics from multiple lung sections from each of five patients with HLHS and a restrictive ASD were compared to those of five patients with HLHS and nonrestrictive ASD. Lung sections from each patient were qualitatively graded in severity of pathology from 0 to 3 for each of the structures described previously, with the pathologist blinded to the status of the ASD. Patients with a restrictive ASD exhibited more significant pulmonary venous thickening and lymphatic dilatation (p = 0.02), with a tendency toward persistence of high-resistance fetal vessels (p = 0.2), compared to patients with a nonrestrictive ASD. These findings imply that patients with HLHS and a restrictive ASD possess pulmonary vascular abnormalities that place them at higher risk for the current surgical interventions available compared to patients with a nonrestrictive ASD

A Doppler myocardial performance index, defined as the sum of the isovolumetric contraction and relaxation time divided by the ejection time (ICT + IRT/ET), reflects global cardiac function, and when applied to the left ventricle, may serve as a predictor of moderate rejection in pediatric cardiac transplant patients

High intensity focused ultrasound (HIFU) is an evolving technology with potential therapeutic applications. Utilizing frequencies of 500 kHz to 10 MHz, HIFU causes localized hyperthermia at predictable depths without injuring intervening tissue. Applications in neurosurgery, urology, oncology and, more recently, cardiology for selective cardiac conduction tissue ablation have been promising. A 'noninvasive' technique for causing localized tissue damage to relieve hemodynamic and life-threatening obstruction in patients with congenital cardiac anomalies could replace more invasive procedures. We, therefore, investigated the ability of HIFU to create lesions in mammalian cardiac tissues ex vivo. Porcine valve leaflet, canine pericardium, human newborn atrial septum, and right atrial appendage were studied. Specimens were mounted and immersed in a water bath at room temperature. Using a 1-MHz phased array transducer, ultrasound energy was applied with an acoustic intensity of 1630 W/cm(2) or 2547 W/cm(2) until a visible defect was created (duration 3 to 25 sec). Macroscopic and microscopic examination demonstrated precise defects ranging from 3 to 4 mm in diameter. No damage was identified to the surrounding tissues. Our study concluded that HIFU can create precise defects in different cardiac tissue without damage to the surrounding tissue. Further investigation is needed to assess potential clinical uses of this technology

BACKGROUND: Invasive techniques such as amniocentesis and cordocentesis are used for diagnosis and treatment in fetuses at risk for anemia due to maternal red-cell alloimmunization. The purpose of our study was to determine the value of noninvasive measurements of the velocity of blood flow in the fetal middle cerebral artery for the diagnosis of fetal anemia. METHODS: We measured the hemoglobin concentration in blood obtained by cordocentesis and also the peak velocity of systolic blood flow in the middle cerebral artery in 111 fetuses at risk for anemia due to maternal red-cell alloimmunization. Peak systolic velocity was measured by Doppler velocimetry. To identify the fetuses with anemia, the hemoglobin values of those at risk were compared with the values in 265 normal fetuses. RESULTS: Fetal hemoglobin concentrations increased with increasing gestational age in the 265 normal fetuses. Among the 111 fetuses at risk for anemia, 41 fetuses did not have anemia; 35 had mild anemia; 4 had moderate anemia; and 31, including 12 with hydrops, had severe anemia. The sensitivity of an increased peak velocity of systolic blood flow in the middle cerebral artery for the prediction of moderate or severe anemia was 100 percent either in the presence or in the absence of hydrops (95 percent confidence interval, 86 to 100 percent for the 23 fetuses without hydrops), with a false positive rate of 12 percent. CONCLUSIONS: In fetuses without hydrops that are at risk because of maternal red-cell alloimmunization, moderate and severe anemia can be detected noninvasively by Doppler ultrasonography on the basis of an increase in the peak velocity of systolic blood flow in the middle cerebral artery

Abnormalities of the mitral valve (MV) or the tricuspid valve (TV) morphology and/or function in patients with functional single ventricle may result in early morbidity and death. The purpose of this study was to determine the incidence of contralateral atrioventricular valve (AVV) pathologies in mitral valve atresia (MA) and tricuspid valve atresia (TA). We retrospectively reviewed the echocardiographic data of 50 neonates with MV and 20 with TA. Appearance of the papillary muscles, chordae tendinae, and valve leaflets was assessed. AVV regurgitation was semiquantitated by color-flow Doppler and the AVV annulus diameter was measured and indexed to body surface area. MV abnormalities were found in 9 of 20 (45%) of patients with TA. The MV was myxomatous in 9 patients, the leaflets were redundant in 5 patients, and prolapsing occurred in 4 patients. Mild regurgitation was found in 2 patients. In 18 of 20 (90%) patients MV annulus size was larger than 95% of predicted normal values. TV abnormalities were found in 12 of 50 (24%) patients with MA. The TV was myxomatous in 4 patients, prolapsing in 2, and redundant in 3, and moderate TV regurgitation was found in 3 patients. In 29 of 50 (58%) patients TV annulus size was larger than 95% of predicted normal values. Contralateral AVV abnormalities in tricuspid and mitral valve atresia are common and should be assessed carefully before surgical procedures

This study is a retrospective review using transthoracic echocardiography to assess the success of fenestration closure as well as residual right to left shunts in 35 patients who underwent Fontan fenestration closure in the catheterization laboratory. There is a high rate of closure of the Fontan fenestration; however, other residual right to left shunts are common