Electrical stimulation of skeletal muscle for cardiac assistance

Skeletal muscle grafts could be used in a number of configurations to assist the failing heart. We have focused on the skeletal muscle ventricle (SMV), formed by rolling a flat muscle (the latissimus dorsi) into a blind-ended tube. The open end is connected to the aorta, and the SMV is activated out of phase with the natural heart as a counter-pulsator. The intended effect of this action is to raise aortic diastolic pressure (and thus enhance the perfusion of the myocardium itself) and by emptying and relaxing before the next left ventricular ejection, to reduce the impedance seen by the left ventricle and thus to reduce its workload. We have incorporated our knowledge of the mechanical behaviour of electrically stimulated skeletal muscle into numerical models first of muscle itself, and then of SMVs. The resultant validated models have now been incorporated into established models of the normal and the failing cardiovascular system. We can therefore perform virtual experiments to test the effect of changes in the synchronization of the two pumps, of variations in the degree of failure of the natural heart, of variations in the properties of the great vessels, and of variations in the performance of the SMV. We are confident that by taking into account the properties of electrically stimulated skeletal muscle, SMVs can be designed that will assist the human heart both safely and effectively