Numerical comparison of hemodynamics with atrium to aorta and ventricular apex to aorta VAD support.

We report the first attempt to study with numerical methods ventricular assist device (VAD) models and the effects of various inlet VAD cannulations, coupling physical explanations and numerical investigation conclusions with clinical research results. We compared the hemodynamic response with VAD support by using two distinct VAD-inlet cannulation configurations: left atrium to aorta and left ventricular apex to aorta. Impeller pump and displacement pump VADs are considered. Constant VAD flow rate and counterpulsation motion models are simulated. The native cardiovascular system is modeled using the concentrated-parameter method by considering the flow resistance, vessel elasticity, and inertial effect of blood flow in cardiovascular system individual segments. Impeller and displacement pump dynamic models are represented by corresponding inlet and outlet flow rate changes in the VADs. Results show that the two VAD inlet cannulation configurations produce similar cardiac response (flows, pressures, volumes), except that when the VAD flow approaches the 100% assisting condition, the peak left ventricular systolic pressure and diastolic volume increase slightly in the left atrial cannulation, whereas they drop markedly in the left ventricular apex cannulation, suggesting increased ventricular wall tension and ventricular dilatation in the left atrial cannulation and that hemodynamically the left ventricular apex cannulation is more advantageous.