A miniaturized artificial heart is being developed in the authors laboratories, the Auxiliary Total Artificial Heart (ATAH). This device is an electromechanically driven ATAH using a brushless direct current (DC) motor fixed in a center aluminum piece. This pusher plate type ATAH is controlled based on Frank-Starling's law. The beating frequency is regulated through the change of the left preload, assisting the natural heart in obtaining adequate blood flow. With the miniaturization of this pump, the average sized patient can have the surgical procedure of implantation in the right thoracic cavity performed without removal of the natural heart. The left and right stroke volumes are 35 ml and 32 ml, respectively. In vitro tests were made and the performance curves demonstrated that the ATAH produces 5L/min of cardiac output at 180 bpm (10 mmHg of left inlet mean pressure and 100 mmHg of left outlet mean pressure). Preliminary acute In vivo tests were performed in two sheeps with 50 ± 5 kg, during 5 hours. The ATAH performance is satisfactory for helping the natural heart to obtain the required blood flow and arterial pressure. With the ATAH and the natural heart working simultaneously the ATAH control system is simpler, also the risks of a fatal misoperation is minor compared to a total artificial heart, for patients that still present some cardiac function.
Heart-assist devices; Heart; Transplantation
