A ventricular assist device powered by conditioned skeletal muscle

Background. We are developing and testing a new ventricular assist device ( VAD) to be powered by conditioned skeletal muscle. Methods. To evaluate the VAD hardware and to develop a muscle training regi men, 8 calves have been used in studies in which the right latissimus dorsi muscle was employed. The experiments were carried out to an approximately 4-month duration. Results. There was significant conversion of type II (fast twitch) to type I (slow twitch) muscle fibers. This did not correlate well, however, with d evice performance. The device stroke volumes ranged from approximately 17 t o 90 cc. This variability of outcome occurred despite the fact that identic al hardware, surgical procedures, and training regimens were employed. Conclusions. The results from the first eight studies lead us to speculate that perfusion may be important even when the muscle is working at pressure s much lower than systemic blood pressure levels. In an attempt to augment tissue perfusion, we plan to investigate thermally induced angiogenesis as a possible mechanism for increasing blood flow to the tissue. (C) 1999 by T he Society of Thoracic Surgeons.