EFFECT OF CONTINUOUS-FLOW LEFT VENTRICULAR ASSIST DEVICE ON CARDIAC FUNCTION: SIMULATION STUDY WITH A BIVENTRICULAR COMPUTER MODEL

摘要

Left ventricular assist device (LVAD) therapy has become an established treatment for patients with end-stage heart failure as either a bridge to transplant (BTT) or as permanent support (destination therapy: DT) [1]. For a small portion of patients, LVAD could be used as a bridge to cardiac recovery (BTR). Recent clinical studies have demonstrated the advantages of continuous-flow LVADs over pulsatile-flow counterparts with respect to higher survival rates and lower incidence of major adverse events [2]. However, the control challenge of continuous-flow LVADs has been not fully addressed: most of the devices are driven at a constant speed, which does not take into account changes in patient physiologic demands [3,4]. Several numerical simulation studies to optimize the LVAD speed control have been reported, most of which follow the traditional linear assumption of end systolic pressure volume relationship (ESPVR) to simulate the ventricular contraction. Decades of research has demonstrated the importance of ESPVR as an index of ventricular systolic function [5, 6] and, furthermore, that the ESPVR is curvilinear [7, 8], particularly in the case of dilated cardiomyopathy. Yet, very few studies have employed curvilinear ESPVR in cardiac computational simulation [3,9]; and none have investigated the impact of the curvilinear ESPVR on VAD hemodynamics. The present study was undertaken to investigate the implications of nonlinear ESPVR on the pump speed regulation of a continuous-flow LVAD.