['In an effort to evaluate pharmacologic agents for optimal anticoagulant prophylaxis in patients undergoing free tissue transfer, we evaluated the efficacy of desirudin (Canyon Pharmaceuticals, Hunt Valley, MD), a recombinant hirudin that acts as a direct thrombin inhibitor, using a rat model of microvenous thrombosis.', 'Randomized, blinded study using an in vivo rat model of microvenous failure.', 'Thirty-two rats received either desirudin or saline in a randomized, blinded fashion 30 minutes prior to performance of a standardized thrombogenic procedure on rat femoral veins. Bleeding time, vessel patency, and presence of clot within the anastomosis were subsequently assessed. Appropriate statistical analyses were then performed.', 'There was a significant increase in vessel patency in rats treated preoperatively with desirudin compared to controls receiving saline (96.9% vs. 53.1%, P < .001). In evaluating patent vessels for non-occluding clot, 41.2% of control rats had non-obstructive clot at the site of anastomosis, versus 3.2% of rats treated with desirudin (P = .002). Bleeding times were longer in desirudin-treated rats than those that received saline (7.17 +/- 3 minutes vs. 5.15 +/- 1.2 minutes, P = .027).'] Does desirudin reduce the rate of microvenous thrombosis in a rat model?