Intraventricular Fluid Mechanics in Advanced Heart Failure patients implanted with Left Ventricular Assist Devices

LVAD improvements have reduced pump-related complications and open a way for long-term treatment of heart failure that can compete with heart transplantation. Stroke of unknown origins has remained unacceptably high, bringing the focus on intraventricular hemodynamics, now that pump hemodynamics are milder and better understood. Our labs have studied the fluid mechanics in ventricles with advanced heart failure, implanted with an LVAD at the apex. The role of recirculation near the apical pocket created by the LVAD inflow cannula, low velocities in the LV outflow track due to closed aortic valve, pump flow rate dependency on preload dependencies of different LVADs in the market, and the speed modulation schemes recently introduced by manufacturers to mimic pulsatility in these continuous centrifugal pumps, have been studied by a combination of computational simulations and in-vitro experiments with time-resolved stereo PIV. We describe the general features of flow in a ventricle that doesn’t significantly change shape or volume (consistent with advanced heart failure implanted with a continuous flow pump), and characterize the recirculation regions, quantifying stasis to perform comparisons that could help understand the impact of hemodynamics on thrombosis. Different Eulerian metrics are defined for the whole ventricle, moving away from the paradigm of Wall Shear Stress, and a novel Lagrangian strategy to quantify platelet trajectories and their exposure to stasis inside the ventricle is presented.