EXPERIMENTAL DEVELOPMENT OF AN ELECTRICALLY STIMULATED BIOLOGICAL SKELETAL-MUSCLE VENTRICLE FOR CHRONIC AORTIC COUNTERPULSATION

Objective: The chronic shortage of donor organs for cardiac transplant ation and the high costs for mechanical assist devices demand the deve lopment of alternative cardiac assist devices for the treatment of sev ere heart failure. Cardiac assistance by stimulated skeletal muscles i s currently investigated as such a possible alternative. The goal of t he presented study was to construct a newly designed biological skelet al muscle ventricle and to evaluate its possible hemodynamic efficacy in an acute sheep model. Methods: A total of 14 adult sheep were used for acute experiments. The entire thoracic aorta including the aortic root was excised from a donor sheep. An aorto-pericardial pouch condui t (APPC) was created by enlarging the aortic circumference in its midd le section with two strips of pericardium. This biological conduit was anastomosed in parallel to the descending aorta of a recipient sheep, using the aortic root as an inflow valve to the conduit. Stimulation electrodes were applicated to the thoracodorsal nerve and the latissim us dorsi muscle was detached from the trunk and wrapped around the pou ch. EGG-triggered functional electrical stimulation was applied during cardiac diastole to simulate aortic counterpulsation. Stimulation was performed during various hemodynamic conditions. Results: A standardi sed surgical procedure suitable for long term studies was established during six experiments. An APPC, with 70-80 mm filling volume, was fou nd to be of optimal size. In another eight experiments, hemodynamic me asurements were performed. Under stable hemodynamic conditions the sti mulation of the biological skeletal muscle ventricle induced a signifi cant increase of mean arterial pressure by 14% and mean diastolic pres sure by 26%. During pharmacologically induced periods of cardiac failu re, the stimulation of the APPC increased mean arterial pressure by 13 % and mean diastolic pressure by 19%. In all eight experiments, the di astolic peak pressure reached supra-systolic values during stimulation . Conclusions: The results demonstrate the hemodynamic efficacy of thi s newly designed biological skeletal muscle ventricle as an aortic cou nterpulsation device. Chronic experiments using a preconditioned fatig ue-resistant muscle will further help to evaluate its possible clinica l significance. (C) 1998 Elsevier Science B.V.