Research activities are primarily related to the design, testing, and manufacturing of implantable circulatory support devices, especially the Total Artificial Heart (TAH) and Ventricular Assist Device (VAD). These systems are intended for long-term support for patients who are not candidates for cardiac transplantation, or whom are unlikely to receive scarce donor organs. The risk of infection is reduced by eliminating percutaneous conduits. Power is delivered to the implant transcutaneously, via inductive coupling. Long-term implantable devices present a number of engineering challenges in order to meet the requirements of long life, high reliability, small size, and energy efficiency. Dr. Weiss' research focuses on the hemodynamic and energetic performance of the TAH and VAD, using analysis, simulation, and in vivo and in vitro experiments. Other specific research areas include inductive energy transmission, wireless telemetry, instrumentation, and electric motor design and control. Complete system simulation is used to study the interactions among the major subsystems: the cardiovascular system, the blood pump and valves, the electromechanical pump actuator, the implanted controller (hardware and software), batteries, and the transcutaneous energy transmission system. In vitro and in vivo studies are used to study the dynamic performance and energetic efficiency of the VAD and TAH. For example, interaction between the VAD and the native heart and circulation is of interest. Indices of device function, including VAD rate and other control variables, are affected by native heart rate and contractility, surgical placement of vascular conduits, patient position, and mechanical changes in the VAD device itself Analysis of VAD function will aid in patient management, detection of changes in VAD and patient hemodynamics, and failure prediction. These research activities are conducted in the facilities of the Section of Artificial Organs in the Department of Surgery of the College of Medicine.