Skeletal muscle as a myocardial substitute.

Skeletal muscle has long been used in the field of cardiac surgery. Its use has progressed from providing myocardial reinforcement to assisting the heart by actively pumping blood. Early experiments revealed that skeletal muscle assistance could augment pressures and blood flow; however, the results were short-lived due to muscle fatigue. It was later shown that skeletal muscle can be conditioned electrically to be fatigue resistant and therefore may be useful for performing cardiac-type work. Once the details were formed of how to stimulate and manipulate the muscle to assist the heart, several configurations were devised. Cardiomyoplasty and aortomyoplasty refer to wrapping skeletal muscle around the heart or aorta, respectively. These techniques have been applied in humans; however, the effectiveness is controversial. Although most patients improve clinically, the hemodynamic parameters have not shown consistent improvements, and survival data are unknown. Skeletal muscle ventricles offer a promising alternative to both cardiomyoplasty and aortomyoplasty. These are completely separate pumping chambers constructed from skeletal muscle and connected to the circulation in a variety of configurations. Although these have not been tried in humans, the animal data appear quite convincing. The skeletal muscle ventricles have shown the greatest improvements on hemodynamic parameters with great stability over time.