Cardiomyoplasty: the benefits of electrical prestimulation of the latissimus dorsi muscle in situ

Background. Ischemic damage in the latissimus dorsi muscle may limit the success of cardiomyoplasty. Electrical prestimulation of the muscle in situ is known to enhance thoracodorsal perfusion to the distal latissimus dorsi muscle immediately after grafting. In this study we asked whether prestimulation was also beneficial under typical postoperative conditions. Methods. Ten sheep were randomly assigned to two equal groups. In one group the latissimus dorsi muscle was stimulated continuously in situ at 2 Hz for 2 weeks; in the other group the muscle was not stimulated. Regional blood flows in the muscle were determined sequentially (1) under baseline conditions, (2) immediately after surgical mobilization, handling, and reattachment at 80% of the resting length, and (3) after 5 days. Results. Manipulation of the unstimulated muscle resulted in an acute global reduction in blood flow with no improvement after 5 days. The distal region was most severely affected (26.2% ± 4.2% of baseline blood flow). Electrical prestimulation significantly reduced regional blood flow under baseline conditions but rendered the whole muscle more resistant to the surgical manipulations; blood flow was significantly better-preserved immediately afterwards, and there was complete recovery to baseline levels after 5 days. Conclusions. Electrical prestimulation of the latissimus dorsi muscle in situ reduces the acute distal ischemia caused by surgical manipulations, and promotes subsequent recovery of blood flow to baseline levels after a few days. Use of a prestimulated graft may therefore improve the outcome of skeletal muscle cardiac assistance.