A model to study volumetric performance of pusher-plate blood pumps

The research reported here elucidated mechanisms that affect volumetric performance of pusher-plate type artificial hearts and ventricular assist devices, built a system model, and demonstrated use of the model as a design tool. Volumetric performance mechanisms were studied using a Penn State Electric Left Ventricular Assist Device (LVAD) operating on a mock loop. The LVAD uses a pusher-plate that moves forward to compress a flexible blood sac, then retracts while the blood sac fills. Tilting disk valves at the inlet and outlet to the pump chamber enforce the direction of flow, and result in some volumetric losses.;Evidence has suggested that ventricle shape, device beat rate, and connector length all influence volumetric performance; the reasons were not well understood. The existing mathematical models of the devices and the circulation were useful in evaluating and predicting device performance, but did not adequately explain some of the observed phenomena.;This research made significant contributions in several areas. A condition known as flow-through was documented and correlated with outlet inertance. Two indices of volumetric performance were used to measure performance under various conditions. This work completed development of a dynamic model of tilting disk prosthetic heart valves. The valve model was validated using data from a test set-up, and was successfully implemented in a model and simulation of the LVAD and mock loop. The system model was built using a continuous model of ventricular compliance that can be used for filling and ejection without making a model change based on the sign of flow, pressure, or pusher-plate direction. The model and simulation developed here validated the concept of tracking the volume in the ventricle during a simulation.