Nuclear Scanning With Technetium-99m-Sestamibi to Evaluate Ischemia in Muscle Flaps for Cardiomyoplasty

Mobilization of the latissimus dorsi muscle from the chest wall for cardiomyoplasty interrupts part of its blood supply. The time required for adequate collaterals to develop from the thoracodorsal artery is unknown. In four dogs, the latissimus dorsi muscle was mobilized as for cardiomyoplasty and stimulating electrodes were implanted. The muscle was replaced on the chest wall over a sheet of Gore-Tex (W. L. Gore & Associates, Inc. Flagstaff, AZ) membrane to block growth of collateral vessels from the chest wall. The opposite latissimus dorsi muscle served as the control. After a delay of 2 weeks the latissimus dorsi was burst stimulated at a rate of 80 per min with two 100 msec bursts at 85 Hz and 25 Hz for 30 min. Technetium-99m-sestamibi scans were then done to detect ischemia. Serial studies were done during the next several weeks. Images at 4 weeks demonstrated maximum uptake in the mobilized muscle, which did not subsequently improve. The authors conclude that the mobilized latissimus dorsi muscle can be imaged with technetium-99m-sestamibi and evidence of ischemia resolves at 4 weeks. These findings suggest that collateral flow is adequate as early as 4 weeks after mobilization of the latissimus dorsi muscle for cardiomyoplasty.