Local application of FFR-rFVIIa reduces thrombus formation at arterial anastomosis in rats

Thrombosis is still a significant problem in microvascular surgery. The aim of this study was to evaluate the antithrombotic effect of topically applied active site-inhibited recombinant human factor VIIa (FFR-rFVIIa) in a rat model with microvascular thrombosis. Forty-five male rats were allocated to one of three groups: local treatment with vehicle only, local treatment with 0.035 mg of FFR-rFVIIa, or local treatment with 0.35 mg of FFR-rFVIIa. An arteriotomy was made in the right femoral artery. Ten minutes following topical application, a thrombogenic anastomosis was performed. Using a transilluminator, thrombus formation and anastomotic bleeding episodes were observed and registered for 40 min. Local application of FFR-rFVIIa resulted in a 85-90% reduction of thrombus formation in both treated groups compared to the control group, but the reduction was only statistically significant in the group treated with 0.035 mg of FFR-rFVIIa. An increased occurrence and duration of anastomotic bleeding episodes were observed in both FFR-rFVIIa-treated groups.