A QUANTITATIVE EVALUATION OF AORTIC VALVE INSUFFICIENCY DURING LVAD USE

Abstract

The aim of this study was to quantitatively evaluate the effect of aortic insufficiency (AI) on the hemodynamics of LVAD patients. A Micromed Debakey continuous flow LVAD was connected to the SDSU cardiac simulator and the distal aortic and LVAD flow measured under series and parallel flow conditions at three different LVAD pump speeds (7.6, 9 and 12.2 krpm) in combination with three different simulator waveforms (Off, Lo and Med). Data were obtained using a normal porcine bioprosthetic valve (N) and with one damaged with a 5 mm hole at the leaflet tip (D). The ratio of LVAD to aortic flow indicates the functional contribution of the LVAD to the total cardiac output (see figure). A ratio of one indicates a series flow condition is present (N, N-Lo); less than one indicates that flow is in parallel, with an increasing value representing a decreasing contribution by the heart (N-Med). Ratios greater than one indicate AI of the damaged valve (D), which is improved by increasing the pumping contribution of the heart (D-Lo, D-Med). Results show that AI produces recirculation that increases pump work and decreases systemic perfusion. Aortic valve competency is critical for LVAD patient health and should be verified or corrected at the time of LVAD implantation.Figure