In vitro Investigation of the effect of native contractility and left ventricular assist device support on intraventricular hemodynamics

Left Ventricular Assist Devices (LVADs) are rotary continuous flow pumps that are implanted to support cardiac function for end-stage heart failure. This study investigates hemodynamic patterns in the left ventricle that may promote thrombus formation. Measurements were conducted in a patient-specific thin-walled silicone LV model in a mock circulation loop with refraction-index-matched blood-mimicking fluid. Flow fields were obtained using stereo particle image velocimetry (PIV), and residence time analysis based on washout was conducted using planar laser-induced fluorescence (PLIF). Flow fields and washout were analyzed for varying levels of native contractility with and without LVAD support. Larger regions of stagnation in the LV were measured when ventricle contraction was severely impaired, independent of LVAD support level. High LV contraction reduced thrombogenic flow patterns. Reducing stagnation in the LV is intimately linked to LV contractility, while higher levels of LVAD support play a secondary role. Increased LV contractility also led to large changes in intraventricular pressure, which in turn produced greater heterogeneity of flow patterns throughout the cardiac cycle. This effect is associated with better washout of the LV and reduced risk of clot formation.