Vascular delay and administration of basic fibroblast growth factor augment latissimus dorsi muscle flap perfusion and function

Ischemia of the distal latissimus dorsi muscle flap occurs when the entire muscle is acutely elevated. Although this level of ischemia may not be crit ical if the muscle is to be used as a conventional muscle flap, the ischemi a causes decreased distal muscle function if it is used for dynamic muscle flap transfer. This experiment was designed to determine whether or not the administration of exogenous basic fibroblast growth factor (bFGF), combine d with a sublethal ischemic insult (i.e., vascular delay), would fur-ther a ugment muscle perfusion and function. Both latissimus dorsi muscles of nine canines were subjected to a bipedicle vascular delay procedure immediately followed by thoracodorsal intraarterial injection of 100 mu g of bFGF on o ne side and by intraarterial injection of vehicle on the other. Ten days la ter, both latissimus dorsi muscles were raised as thoracodorsally based isl and naps, with perfusion determined by laser-Doppler fluximetry. The muscle s were wrapped around silicone chambers, simulating cardiomyoplasty, and st imulating electrodes were placed around each thoracodorsal nerve. The muscl es were then subjected to an experimental protocol to determine muscle cont ractile function. At the end of the experiment, latissimus dorsi muscle bio psies were obtained for measurement of bFGF expression. The results demonst rated that the administration of 100 mu g of bFGF immediately after the vas cular delay procedure increases expression of native bFGF. In the distal an d middle muscle segments, it also significantly increased muscle perfusion by approximately 20 percent and fatigue resistance by approximately 300 per cent. The administration of growth factors may serve as an important adjuva nt to surgical procedures using dynamic muscle nap transfers.