Intraarterial urokinase increases skeletal muscle viability after acute ischemia

Administration of intraarterial fibrinolytic agents has been recommended after balloon catheter thrombectomy to reduce retained thrombus and to improve the patency of collateral vasculature. However, the potential for improvement in the viability of skeletal muscle after ischemia as a result of this therapy has not been evaluated. We investigated the effect of intraarterial urokinase (UK) on the salvage of ischemic skeletal muscle in a bilateral, in vivo, isolated gracilis muscle model. In six anesthetized dogs each gracilis muscle was subjected to 5 hours of ischemia by temporary occlusion of the gracilis artery. Before reperfusion, the experimental muscle received an intraarterial infusion of UK (30,000 units) whereas the control muscle received saline solution. Each muscle was then reperfused for 90 minutes. Triphenyltetrazolium chloride staining demonstrated infarction of 20.2% +/- 8.1% in control muscles compared with 8.6% +/- 6.2% in UK-infused muscles (p less than 0.01). Control muscles gained significantly more weight from edema (33.6 +/- 5.9 gm) than UK-infused muscles (18.2 +/- 4.1 gm; p less than 0.05). Coagulation studies confirmed that an isolated fibrinolytic effect occurred on the experimental side. These studies suggest that intraarterial UK may be a useful adjunctive therapy after revascularization of the acutely ischemic limb and that further clinical trials are recommended.