Evaluation of the Effect of Bosentan-Mediated Endothelin Receptor Blockade on Flap Survival in Rats: An Experimental Study.

Local skin flaps are important tools for performing plastic surgery. Skin flaps are used for closure of defects after tumor excision or in tissue losses after trauma. However, problems associated with these flaps are commonly encountered, particularly in areas of marginal necrosis. Bosentan is a vasodilator that exerts its effect through endothelin receptor blockade, and has been shown to prevent ischemic tissue damage. However, no reports have addressed the effect of bosentan on skin flaps. The aim of the study was to investigate the effects of bosentan, which may be applied clinically to promote survival of ischemic skin flaps. A modified McFarlane flap was elevated in the dorsum of 20 Albino Wistar rats with a width-to-length ratio of 3 to 10 cm, respectively, with the caudal base. Perioperatively, 0.9% of physiologic NaCl and injectable distilled water of identical volume were injected into rats in Group 1 (n = 10), and 5 mg/kg bosentan was injected intraperitoneally into rats in Group 2 (n = 10). All of the rats were followed up for 7 days postoperatively. The surviving parts of the flaps were measured at the end of day 7. Acute and chronic inflammation, amount of granulation tissue, fibroblast maturation, amount of collagen, and amounts of reepithelialization and neovascularization present in the ischemic zones of the distal parts of the flaps were evaluated histopathologically, and results were compared statistically. The mean flap survivals were 61.1% in Group 1 and 91.1% in Group 2; the percentage of the surviving flap area in Group 2 was higher than that in Group 1 (p < 0.005). In both groups, there was significantly less acute inflammation in the ischemic zones in Group 2 than in Group 1 (p < 0.005). No significant difference was found in the amounts of chronic inflammation and granulation tissue between the two groups (p > 0.005). Fibroblast maturation, amount of collagen, and amounts of reepithelialization and neovascularization investigated in Group 2 were statistically significantly higher than those in Group 1 (p < 0.005). We believe that bosentan may be used prophylactically to increase survival in risky skin flaps because it decreases ischemic necrosis distal to skin flaps, thus exerting favorable effects on flap survival.