VASCULAR DELAY IMPROVES LATISSIMUS-DORSI MUSCLE PERFUSION AND MUSCLE FUNCTION FOR USE IN CARDIOMYOPLASTY

Ischemia of the distal portion of the latissimus dorsi muscle occurs i n muscle transfer for cardiomyoplasty and reduces distal muscle contra ctility and thus the mechanical effectiveness of cardiomyoplasty. We h ypothesized that muscle function would be improved by a vascular delay procedure that increases distal muscle perfusion of the latissimus do rsi muscle. The latissimus dorsi muscles of 10 adult mongrel dogs were subjected to a vascular delay procedure on one side and a sham proced ure on the other. Following 10 days of vascular delay, muscle perfusio n was measured with a laser-Doppler perfusion imager before and after elevation of the muscles as flaps based only on their thoracodorsal ne urovascular pedicles. The muscles were wrapped and sutured around sili cone chambers (simulating cardiomyoplasty), a stimulating electrode wa s placed around each thoracodorsal nerve, and. the muscles were stimul ated to contract in both rhythmic and tetanic fashion. Circumferential (distal and middle latissimus dorsi muscle function) and longitudinal (proximal latissimus dorsi muscle function) force generation and fati gue rates were measured independently. Circumferential muscle force, c ircumferential and longitudinal fatigue rate, and distal, middle, and overall perfusion were significantly (p < 0.05) improved in delayed mu scle compared with nondelayed muscle. We found that a vascular delay p rocedure and a 10-day delay adaptation period significantly improve la tissimus dorsi muscle flap perfusion and function, particularly in the distal and middle portions of the muscle. Delay should be considered as a means of improving the clinical out-come in cardiomyoplasty.