Influence of topical heparin on stasis-induced thrombosis of microvascular anastomoses.

An experiment was done to determine whether topical heparin and the association of anastomoses with dependent tissue (free flaps) exert any influences on stasis-induced microvascular thrombosis. Rat femoral vessel anastomoses with or without free flap construction were used in a total of 50 male Sprague-Dawley rats. Saline either with or without heparin was used for intralumenal irrigation during the anastomosis. Following anastomotic repair, the femoral vessels were reclamped, inducing stasis for either 2 or 4 hr. Our results showed that static blood had little adverse effect on thrombosis at the arterial anastomosis when reclamped for up to 4 hr in both standard and flap-associated anastomoses. Topical heparin significantly reduced the incidence of stasis-induced thrombosis of venous anastomoses. The venous patency rates in standard anastomoses were lower than those in flap-associated anastomoses after both 2 and 4 hr of stasis. From these results, we conclude the following. 1) Arteries may be reclamped for up to 4 hr without detriment despite static blood being in contact with the anastomotic site. 2) Topical heparin may be helpful in increasing the patency rate of venous anastomoses after a period of blood stasis. 3) Free flap construction may play a role in decreasing stasis-induced microvascular thrombosis.