INTRAVASCULAR HEPARIN PROTECTS MUSCLE FLAPS FROM ISCHEMIA-REPERFUSIONINJURY

Heparin has been found to decrease ischemia/reperfusion injury in skel etal muscle and other tissue/organ systems. The timing of heparin admi nistration to the muscle vasculature has not been explored. We investi gated the use of heparinized blood as a washout solution during ischem ia to reduce ischemia/reperfusion injury. A rat cutaneous maximus musc le free flap was subjected to a 10-hr period of room temperature ische mia, then was heterotopically transplanted to the groin via microsurgi cal revascularization to the femoral vessels, In three experimental gr oups, flaps were subjected to brief ex vivo perfusion with autologous heparinized blood, at 2, 5, or 8 hr into the 10-hr ischemic interval. In the two other groups, the flaps were not perfused, and the animals were systemically heparinized either before ischemia or before transpl antation, respectively. A control group underwent no flap perfusion or systemic heparinization. After transplantation, flaps were given a 48 -hr period of in vivo reperfusion, then were harvested for evaluation, Flaps undergoing ex vivo perfusion or preischemic heparinization had no significant differences in weight gain (edema) compared with flaps receiving posttransplant heparinization or no heparinization (controls ). The dehydrogenase staining of muscle biopsies was significantly fas ter (indicative of viable tissue) for perfused flaps and the flaps for which the animals received preischemic heparinization, when compared with flaps for which the animals received posttransplant heparinizatio n or no heparinization. From these results, we conclude that heparin o ffers protection from ischemia/reperfusion injury when it can be intro duced into the vascular network either prior to or during the ischemia period. These findings suggest the possibility of using heparinized w ashout solutions to enhance survival in amputated extremities. (C) 199 5 Wiley-Liss, Inc.