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

Background. Ischemic damage in the latissimus dorsi muscle may limit the su ccess of cardiomyoplasty. Electrical prestimulation of the muscle in situ i s known to enhance thoracodorsal perfusion to the distal latissimus dorsi m uscle immediately after grafting. In this study we asked whether prestimula tion 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 fo r 2 weeks; in the other group the muscle was not stimulated. Regional blood flows in the muscle were determined sequentially (1) under baseline condit ions, (2) immediately after surgical mobilization, handling, and reattachme nt at 80% of the resting length, and (3) after 5 days. Results. Manipulation of the unstimulated muscle resulted in an acute globa l reduction in blood flow with no improvement after 5 days. The distal regi on was most severely affected (26.2% +/- 4.2% of baseline blood now). Elect rical prestimulation significantly reduced regional blood now under baselin e conditions but rendered the whole muscle more resistant to the surgical m anipulations; blood now was significantly better-preserved immediately afte rwards, and there was complete recovery to baseline levels after 5 days. Conclusions. Electrical prestimulation of the latissimus dorsi muscle in si tu reduces the acute distal ischemia caused by surgical manipulations, and promotes subsequent recovery of blood flow to baseline levels after a few d ays. Use of a prestimulated graft may therefore improve the outcome of skel etal muscle cardiac assistance. (C) 1999 by The Society of Thoracic Surgeon s.