Characterization of pressure oscillations in the Penn State EVAD and mock circulatory system

Previous experiments using the Penn State electric ventricular assist device (EVAD) on the Penn State mock circulatory system show anomalous pressure oscillations in pressure traces taken from the ventricular sac. A lumped parameter mathematical model was developed to characterize the origin of these oscillations. The model was based on a valveless EVAD connected to an aortic tube terminating In a capacitance element. The system was divided into convenient control volumes to which the momentum and continuity equations were applied. A key parameter of the model is the nonlinear quasisteady compliance of the ventricle. The resulting set of independent equations were solved on a computer and compared to measurements taken from the corresponding physical system. The model shows pressure oscillations with similar characteristics to those found in instantaneous pressure traces taken from the physical system