Computational modeling and analysis of intracardiac flows in simple models of the left ventricle

Computational modeling is used to study intracardiac flows in normal and diseased left-ventricles. The left-ventricle is modeled as a semi-prolate-spheroid, and the wall motion is driven by a prescribed ventricular volume-change that consists of five stages: early (E) filling, diastasis, atrial (A) filling, isovolumetric contraction (ISVC) and systole. Simulations are carried out with a parallelized immersed-boundary flow solver that allows us to simulate this flow on a stationary Cartesian grid. The ventricular flow behavior is analyzed to reveal blood flow patterns during both filling and ejection for normal ventricles, as well as ventricles with diastolic and systolic dysfunctions. Impaired relaxation associated with early-stage diastolic dysfunction is modeled by a reduced E/A ratio, and the systolic dysfunction addressed here is obstructive hypertrophic cardiomyopathy (HOCM), where the thickened ventricular septum in the basal region obstructs the outflow tract. Simulations are also performed to study the effect of septal myectomy on the ventricular flow. We examine the characteristic features of these various conditions including vortex dynamics, 'virtual' color M-mode cardiography as well as mixing and transport of blood through the left-ventricle during the entire cardiac cycle.