STIMULATION PARAMETERS OF SKELETAL MUSCLE FOR CARDIAC ASSIST.

The development of a stimulator capable of emitting a train of pulses suitable for stimulating muscle twitches and the use of this pulse-train stimulator to characterize skeletal muscle isometric contractions are described. The optimal stimulation parameters from force and duration of contraction curves were derived for control of canine latissimus dorsi muscles and for the contralateral muscles which had been chronically stimulated over a period of 8 to 18 weeks to induce transformation from a mixed muscle (composed of fast twitch glycolytic type II fibers and slow twitch, fatigue-resistant aerobic type I fibers) to a muscle composed of predominantly type I fibers. Using these optimal stimulation parameters the authors have used these transformed, fatigue resistant muscles to power an extra aortic balloon device for hemodynamically significant cardiac assist through counterpulsation.