Finite element analysis of cardiac ejection dynamics: Ultrasonic implications

Noninvasive echocardiographic and Doppler investigations have been used to improve understanding of ejection in the normal or abnormal left ventricle and aortic root. Computational fluid dynamics may serve to elucidate ultrasonic findings and extend fluid dynamic quantification in cardiology. We present methods from computational fluid dynamics to investigate the effects of simple geometric variations on intraventricular ejection dynamics. Numerical solutions of the Navier-Stokes equations were obtained on the CRAY Y-MP supercomputer by means of finite element analysis. We consider the effects of varying chamber eccentricities and outflow valve orifice-to-inner surface area ratios on instantaneous ejection gradients along the outflow axis of the left ventricle. It was shown that for given chamber volume and orifice area, higher chamber eccentricities require higher ejection pressure gradients for the same velocity and local acceleration values at the aortic anulus than more spherical shapes. This finding is referable to the rise in local acceleration effects across the outflow axis. This is to be contrasted with the case of outflow stenosis, in which it was shown that it is the convective acceleration effects that are intensified strongly. Velocity profiles are shown to be distinctively different, with implications for ultrasonic blood flow determination.

Duke Scholars

Author Ares D. Pasipoularides Surgery, Cardiovascular and Thoracic Surgery