Cardiac assistance with electrically stimulated skeletal muscle.

ABSTRACT

This study examined the ability of a skeletal muscle-powered assist ventricle (SMV) to augment cardiac output in ten dogs with pharmacologically induced heart failure under acute conditions. An SMV was surgically constructed in each dog by wrapping the untrained rectus abdominis muscle around a compressible pouch that was inserted into a left ventricular apex-to-aortic vascular conduit. The multiple motor nerves to the rectus muscle were then stimulated during ventricular diastole at a rate which equalled a ratio of 12, 13, or 14 with the natural ventricular beat. There was an increased cardiac output during SMV assistance compared with preassistance values in all ten dogs at each stimulation ratio with a mean increase of 46 +/- 4 per cent with a ratio of 12, 25 +/- 4 per cent with a ratio of 13, and 31 +/- 7 per cent with a ratio of 14 (p less than 0.01 for all values). The diastolic blood pressure and mean blood pressure were both increased (p less than 0.01 and p less than 0.05, respectively) during SMV stimulation at ratios of 12 and 13, but not 14. We have shown that untrained rectus abdominis muscle, when used as the power supply for a SMV in an apico-aortic conduit, can temporarily augment cardiac output in dogs with pharmacologically induced heart failure.