Freehand three-dimensional echocardiography for measurement of left ventricular mass: in vivo anatomic validation using explanted human hearts

Abstract

Objectives: We sought to validate freehand three-dimensional echocardiography for measuring left ventricular mass and to compare its accuracy and variability with those of conventional echocardiographic methods.

Background: Accurate measurement of left ventricular mass is clinically important as a predictor of morbidity and mortality. Freehand three-dimensional echocardiography eliminates geometric assumptions used by conventional methods, minimizes image positioning errors using a line of intersection display and increases sampling of the ventricle. Preliminary studies have shown it to have high accuracy and low variability.

Methods: Twenty-eight patients awaiting heart transplantation were examined by conventional and freehand three-dimensional echocardiography. Left ventricular mass was determined by the M-mode ("Penn-cube") method, the two-dimensional truncated ellipsoid method and three-dimensional surface reconstruction. The ventricles of 20 explanted hearts were obtained, trimmed and weighed. Echocardiographic mass by each method was compared with true mass by linear regression. Accuracy, bias and interobserver variability were calculated.

Results: For three-dimensional echocardiography, the correlation coefficient, standard error of the estimate, root mean square percent error (accuracy), bias and interobserver variability were 0.992, 11.9 g, 4.8%, -4.9 g and 11.5%, respectively. For the two-dimensional truncated ellipsoid method they were 0.905, 38.5 g, 15.6%, 15.4 g and 23.3%. For the M-mode ("Penn-cube") method they were 0.721, 96.9 g, 53.0%, 109.2 g and 19.5%.

Conclusions: Freehand three-dimensional echocardiography for measurement of left ventricular mass has high accuracy and low variability and is superior to conventional methods in hearts of abnormal size and geometry.