Determinants of left ventricular shape change during filling.

Left ventricular shape and shape change are easy to measure and their analysis has been proposed as a noninvasive method to determine myocardial anisotropy. In preparation for applying this approach to studies of rats with experimentally induced cardiac hypertrophy, the goals of this study were to describe normal shape changes during diastolic filling in the rat and to utilize a finite-element model to estimate the relative importance of three factors that determine left ventricular shape change during filling: global chamber compliance, fiber to crossfiber stiffness ratio, and fiber architecture. The results suggest that left ventricular shape change is least sensitive to fiber to cross fiber stiffness ratio, and that this will likely limit the practical utility of using shape changes to diagnose changes in myocardial anisotropy.