The proposed research is designed to test the ability of a skeletal muscle-powered (rectus abdominis) assist ventricle to augment cardiac output in a chronic study in dogs. The research is based upon a series of studies performed in our laboratory and elsewhere that have demonstrated the feasibility of skeletal muscle powered circulatory assistance. The optimum conduit design in which selected skeletal muscles would most efficiently assist the circulation has not been determined, and the problems of muscle fatigue and lack of a suitable pulse generator to stimulate and coordinate skeletal muscle work are limitations to existing assist systems. The proposed research is divided into 3 separate studies which address these limitations. First we will compare 3 different regimens for converting untrained rectus abdominis muscle to a fatigue-resistant muscle without loss of strength. Feasibility data that show electrically stimulated tetanic contractions against a compressible pouch, at rates of 6-90/min, may prevent muscle injury and optimize muscle conditioning. Second, we will extend preliminary work on a custom designed pulse generator that can sense cardiac activity and be programmed to deliver a specific stimulus. Such a device would have multiple leads delivering a constant current pulse and would be powerful enough to chronically stimulate tetanic muscle contractions via the motor nerve in our rectus ventricle assist system. Third, we will combine our earlier findings, the findings of other investigators, and the results of proposed studies to determine the effectiveness of the rectus assist ventricle for chronically augmenting cardiac output in dogs. The results of this research will provide essential data for future clinical trials of this promising treatment modality for intractable chronic heart failure.
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