IN-VIVO STUDIES OF AN IMPLANTABLE ENERGY CONVERTER FOR SKELETAL-MUSCLE POWERED CARDIAC ASSIST

A device that harnesses the mechanical energy of skeletal muscle contr acting in a linear configuration has been implanted in goats. This ene rgy convertor transforms muscle work to hydraulic energy that could dr ive a variety of cardiac assist devices. The device is mounted with a rib clamp and plate affixed to the sternum by cortical bone screws. A transcutaneous hydraulic line carries a silicon based working fluid to an external system that controls the muscle load. In 60 to 70 kg goat s, the latissimus dorsi insertion was reattached to the energy convert or. A Telectronics myostimulator with intramuscular electrodes stimula ted the latissimus dorsi. In acute implants, hydraulic pressures in ex cess of 150 psi were obtained. Chronic implantation of the device allo wed system evaluation in the conscious unanesthetized animal. Two week s after implant, hydraulic pressures in excess of 200 psi were obtaine d and energy transferred to the external loading system exceeded 1 J p er contraction. Six weeks after implant, the device continued to cycle freely. These initial results are very promising and suggest an impla ntable energy convertor is feasible. Development of an energy converto r is an important step toward tether-free skeletal muscle powered card iac assist devices.