Validation of Noninvasive Measures of Left Ventricular Mechanics in Children: A Simultaneous Echocardiographic and Conductance Catheterization Study

Abstract

The accuracy of echocardiography in evaluating left ventricular contractility has not been validated in children. The objective of this study was to compare echocardiographic measures of contractility with those derived from pressure-volume loop (PVL) analysis in children. Patients with relatively normal loading conditions undergoing routine left heart catheterization were prospectively enrolled. PVLs were obtained via conductance catheters. The gold-standard measure of contractility, end-systolic elastance (Ees), was obtained via balloon occlusion of one or both vena cavae. Echocardiograms were performed immediately after PVL analysis under the same anesthetic conditions. Single-beat estimations of echocardiographic Ees were calculated using four different methods. These estimates were calculated using a combination of noninvasive blood pressure readings, ventricular volumes derived from three-dimensional echocardiography, and Doppler time intervals. Of 24 patients, 18 patients were heart transplant recipients, and six patients had small patent ductus arteriosus or small coronary fistulae. The mean age was 9.1±5.6years. The average invasive Ees was3.04±1.65mmHg/mL. Invasive Ees correlated best with echocardiographic Ees by the method of Tanoue (r=0.85, P<.01), with a mean difference of -0.07mmHg/mL (95% limits of agreement, -2.0 to 1.4mmHg/mL). Echocardiographic estimates of Ees correlate well with gold-standard measures obtained via conductance catheters in children with relatively normal loading conditions. The use of these noninvasive measures in accurately assessing left ventricular contractility appears promising and merits further study in children.