Numerical modeling of the failing ventricle: impact of a nonpulsatile ventricular assist system

The Cleveland Clinic Implantable Ventricular Assist System (IVAS) is a nonpulsatile rotary pump designed to augment the failing left ventricle. The purpose of this study is to assess its impact on the cardiovascular system using computer simulation. The authors modified an existing numerical model (24 coupled differential equations representing all cardiac chambers and systemic and pulmonary vasculature). The pump was added as an auxiliary chamber between the left ventricle (LV) and aorta with pressure flow speed characteristics derived from in vitro testing. Pump function was assessed for normal and failing ventricles at various pump speeds. Computer simulations show that: 1) numerical modeling is useful for predicting hemodynamic response to IVAS; 2) IVAS results in normalization of cardiac output, especially in failing hearts, though with reduced pulse pressure.