LONG-TERM EFFECTS OF DYNAMIC AORTOMYOPLASTY

Aortomyoplasty consists of wrapping the latissimus dorsi muscle (LDM) around the ascending aorta and electrostimulating it during diastole. The ascending aorta will act as an ectopic neo-ventricle compressed du ring diastole, thus reproducing the effects of long-term diastolic cou nterpulsation. In 5 goats, the right LDM was transferred to the thorac ic cavity after removal of the second rib. The ascending aorta was enl arged by a pericardial patch and wrapped with the LDM. Postoperative e lectrostimulation was delivered in a counterpulsating manner. Hemodyna mic studies were performed at 12 and 24 months postoperatively. Percen t increase in the subendocardial viability index (diastolic pressure-t ime index/systolic tension-time index) was calculated using unassisted and assisted cardiac cycles with the stimulator off versus the stimul ator on at a 1:1 ratio in the basal state and after acute heart failur e was induced by the administration of high doses of propranolol hydro chloride. Diastolic counterpulsation of the ascending aorta resulted i n significant improvement in the subendocardial viability index long t erm, both in basal state conditions and after induced cardiac failure. During heart failure, aortomyoplasty increased the cardiac output and decreased systemic vascular resistance. Histopathologic studies up to 24 months showed preservation of the histologic structure of the aort ic wall and no evidence of thromboembolism. Tight adhesions developed between the aortic wall (including the pericardial patch) and the LDM. The diameters of the enlarged aortas showed no significant difference s compared with diameters immediately postoperatively. In conclusion, aortomyoplasty produces chronic diastole augmentation with preservatio n of aortic structure. After induction of heart failure, aortomyoplast y offers efficient circulatory support.