HEMODYNAMIC RESPONSES TO CONTINUOUS AND PULSATILE VENTRICULAR ASSIST IN AN ADULT MOCK CIRCULATION

Abstract

The objective of this study was to investigate hemodynamic responses to continuous (CF) and pulsatile flow (PF) ventricular assist (VAD) in an adult mock circulation. The in vitro preparation consisted of s mock ventricle, systemic vasculature, and coronary network that produce physiologically-equivalent pressures and flows. The mock circulation was instrumented with a ventricular pressure-volume conductance and atrial pressure catheters, and aortic mot, aortic distal, VAD output, and coronary flow probes. CF (BioMedicus, Medtronic) or PF (UVAD85, University of Utah) VAD were connected by ventricular apical and aortic return cannulae. Hemodynamic measurements were recorded for baseline, CF, and PF during simulated normal (CO = 5 L/m), failing (CO = 3 L/m), and partially recovered (CO = 4 L/min) ventricular function with full (VAD output = 5 L/m) and partial (VAD output=2.5 L/m) unloading. PF assist reduced ventricular diastolic elastance (Ed) by providing larger ejection fraction (EF) and reducing ventricular filling pressure (Pd). CF assist slightly increased Ed with d modest increase in EF and a small reduction in Pd. Continuous unloading of the ventricle may result in a smaller ventricular chamber thereby reducing wall stress, but at the possible expense of a stiffer ventricle and redistribution of regional myocardial perfusion. These results may provide important clinical insight into the consequences of assist technique on cardiac mechanics and suggests the potential for unfavorable endocardial perfusion with CF assist.