This Phase II project is concerned with development of a new biventricular assist system (BIVAS) that could be used for patients who require a device for bridge-to-heart transplantation. Envisioned time of use of this BIVAS is either short term (weeks) or long term (1 year plus). In fact, after sufficient bridge experience, it is intended that this system be eventually applied to permanent BIVAS support; a long range goal of this effort. Conceptually, this BIVAS uses two identical axial flow blood pumps implanted adjacent to the native heart for the blood flow devices. Cannulae connected into the right heart and pulmonary artery, and left heart and aorta comprise the rest of the implanted system, along with two small percutaneous cables that provide electrical power and purge fluid to the pumps from an external console. The specific aims of this Phase II project address verification of hemodynamic capability and biocompatibility of the tandem pump concept, and development of an auto regulating speed control system that maintains adequate cardiac output at the same time maintaining safe pulmonary perfusion. Successful development of this system would meet the needs of patients who require biventricular support beyond the confines of short term intensive care situations. Currently, no device has that capability.