PREVENTION OF VENOUS THROMBOSIS IN MICROVASCULAR SURGERY BY TRANSMURAL RELEASE OF HEPARIN FROM A POLYANHYDRIDE POLYMER

Background. The effects of transmurally released heparin on the patenc y of microvenous anastomoses were studied by using a bioerodible polym er delivery system in a rat microvascular thrombosis model. Methods. A polyanhydride carrier with heparin was wrapped around the outside of a highly thrombogenic venous inversion graft in 14 animals, and patenc y rates were compared with those of 17 control animals. Results. Anast omotic patency was significantly greater In the groups treated with tr ansmurrally released heparin, measured both at 24 hours 86% versus 16% ; P < 0.02) and al 7 days (86% versus 36%; p < 0.05) after operation. No significant complications occurred. Conclusions. Controlled release of heparin by transmural delivery is an effective and safe form of lo cal antithrombotic therapy and may have applications both in microvasc ular and large vessel surgery.