Functional Evaluation of Dynamic Cardiomyoplasty in Chronic Heart Failure Model

The mechanism of action of cardiomyoplasty was evaluated in a setting of left heart failure in sheep, using the pressure-volume relationship. A heart failure model was made by ligation of the coronary artery. Three months after infarction, five sheep underwent cardiomyoplasty, using a left latissimus dorsi muscle. After their muscle grafts had been electrically conditioned for 2 months, a terminal experiment was performed. The systemic pressure and cardiac output were not significantly different when measured 3 months after infarction and 2 months after cardiomyoplasty. However, the post-cardiomyoplasty pressure volume-loops generated at the time of terminal measurements were altered in all animals. End-systolic elastance (Ees) increased significantly after cardiomyoplasty, from 2.66 ± 0.41 to 4.59 ± 0.77 mmHg/ml. Pressure-volume area decreased significantly after cardiomyoplasty, compared with post-infarct (1932 ± 275 vs 3776 ± 537mmHg • ml). These findings suggest that the probable mechanism of action of cardiomyoplasty is that it actively supports the geometry of damaged cardiac muscle. The reduced oxygen consumption of the myocardium after cardiomyoplasty may be related to increased ventricular wall thickness and prevention of further ventricular dilatation.