ACUTE HEMODYNAMIC AND PRESSURE-VOLUME RESPONSES TO CONTINUOUS AND PULSATILE ASSIST IN DIMINISHED CARDIAC FUNCTION CALF MODEL

Abstract

Acute hemodynamic and left ventricular pressure-volume responses to continuous flow (CF) and pulsatile flow (PF) ventricular assist devices (VAD) at 50%, 75%, and 100% bypass flow rates were investigated in calves (n=8) with diminished cardiac function (DCF). A clinically relevant DCF model (MAP = 65–75 mmHg, CO = 6–8 L/m, and LAP = 12–15 mmHg) was induced by a single oral dose of Monensin. CF and PF VAD were implanted via ventricular apical and brachiocephallic cannulae. Calves were instrumented with catheters for simultaneous measurement of aortic root pressure (AoP), left ventricular pressure (LVP) and volume (LVV), and aortic, brachiocephallic artery, coronary artery (CoF), and VAD flow probes. PF and CF VAD increased cardiac output, mean AoP, and mean CoF and reduced left ventricular work with increasing levels of VAD support. CF VAD decreased AoP pulsatility with increasing levels of support while PF VAD maintained physiologic pulsatility. Although both CF and PF VAD reduced LVV toward normal, the variation in end-systolic and end-diastolic volume (ΔV) for CF is less with increasing levels of VAD support compared to PF VAD which maintains a normal physiologic ΔV. Though both CF VAD and PF VAD increased diastolic CoF, the augmentation of the diastolic CoF with PF VAD was higher in comparison to CF VAD. The differences in vascular pulsatility, ventricular volume, and myocardial perfusion between VAD type (CF and PF) and level of VAD support may impact device selection, operation, and the potential for myocardial recovery.