Free flap failure is frequently due to tension, twisting, kinking, or compression of the vascular pedicle after the anastomosis is completed A rabbit model simulating these errors was used to evaluate the capacity of topically-applied tissue factor pathway inhibitor (TFPI) to prevent microvascular thrombosis. The rabbit ear was isolated on the central artery and vein the artery was transected, shortened, repaired, and twisted 360° around the vein immediately following the anastomosis, TFPI in concentrations of 1, 4, 10, or 40 μg/ml was irrigated across the lumen. Topically-applied control buffer and heparin (50 U/ml) were compared to TFPI. Treatment with control buffer resulted in a 20 percent survival rate topically-applied heparin improved the survival rate to 60 percent (p <0.05) in contrast. TFPI in concentrations of 4, 10, and 40 μg/ml yielded survival rates of 89, 100, and 97 percent, respectively. This was significantly greater than the heparin-treated ears (p <0.05). TFPI in a concentration of 40 μg/ml was effective in preventing arterial thrombosis when applied for as little as 30 sec; 4 μg/ml was effective in preventing thrombosis when applied for 10 min. These results support the use of TFPI as a topical irrigation solution to help prevent microvascular arterial thrombosis in free-flap surgery.
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