TOPICAL TISSUE FACTOR PATHWAY INHIBITOR IMPROVES FREE-FLAP SURVIVAL IN A MODEL SIMULATING FREE-FLAP ERRORS

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 thes errors was used to evaluate the capac ity of topically-applied tissue factor pathway inhibitor (TFPI) to pre vent microvascular thrombosis. The rabbit ear was isolated on the cent ral artery and vein. The artery was transected, shortened, repaired, a nd twisted 360-degrees around the vein. Immediately following the anas tomosis, TFPI in concentrations of 1, 4, 10, or 40 mug/ml was irrigate d 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 sur vival rate to 60 percent (p < 0.05). In contrast, TFPI in concentratio ns of 4, 10, and 40 mug/ml yielded survival rates of 89, 100, and 97 p ercent, respectively. This was significantly greater than the heparin- treated ears (p < 0.05). TFPI in a concentration of 40 mug/ml was effe ctive in preventing arterial thrombosis when applied for as little as 30 sec; 4 mug/ml was effective in preventing thrombosis when applied f or 10 min. These results support the use of TFPI as a topical irrigati on solution to help prevent microvascular arterial thrombosis in free- flap surgery.