IN VITRO AND IN VIVO EVALUATION ON HEAT DISSIPATION OF ELECTROHYDRAULIC TOTAL ARTIFICIAL HEART

Abstract

We evaluated the heat transfer characteristics of an electrohydraulic total artificial heart (EH-TAH) that have been developed at our institute. In two in vitro experiments, the heat dissipation way of the TAH was investigated. First, we simulated heat transfer of the calf circulation by using a heat exchanger. The amount of heat dissipating directly from the TAH surface and that to the blood chamber were estimated to be almost the same. Second, the temperature of the actuator examined with thermography was found to be almost uniform, and no prominent high temperature area was observed. In an to vivo study, the TAH was implanted in a calf weighing 62kg for 10 days. The input power to the device was 18±2 W, the temperature of the actuator-tissue contacting surface was 39-41°C. This slight temperature elevation was thought to be attributable to the heat dissipation to the blood. Upon histological study of the chest wall and the lung in contact with the actuator, vascularized connective tissue envelopes were observed and unfavorable side effects such as tissue necrosis were not observed. These results suggest that the thermal effect of this system is acceptable at this input power