IN-VITRO PERFORMANCE OF A ROTARY BI-VENTRICULAR ASSIST DEVICE

Abstract

The purpose of this study was to evaluate the hydraulic and hemodynamic performance of a single rotary Bi-Ventricular Assist Device in an in-vitro pulsatile mock circulation loop. Successful development of this device will provide a suitably miniature device for patients who require bi-ventricular assistance. The rotary Bi-VAD includes a left and right impeller positioned on a common rotating hub to form a double sided centrifugal impeller. The vanes of each side are designed to produce the pressure differential and perfusion rates required of the systemic and pulmonary systems. For initial testing, the impeller was centrally located within the dual pump cavity by a conventional shaft, and sealed bearings. A micrometer mechanism allowed precise axial displacement of the impeller in order to simultaneously alter the clearances above the impeller blades. The response of the device to a number of degrees of bi-ventricular heart failure was investigated. The bi-ventricular assist device successfully restored hemodynamic perfusion from pathological to normal levels in a mock circulation loop replicating Bi-Ventricular heart failure. The imbalance of flow required from the left and right hearts was varied by altering the axial clearance above each impeller, and thus the efficiencies of each stage. The observed leakage from the high pressure left to low pressure right chamber was minimized to clinically acceptable levels. The in-vitro results encourage device progression to in-vivo animal studies.