Rat femoral vein-to-vein grafts as a microvascular practice model: factors that influence patency.

The rat femoral vein has become a standard model for microvascular anastomosis practice as well as for research investigations into various manipulative influences upon venous patency. Although vein grafts to the rat artery are the focus of many experimental studies, few reports have investigated vein-to-vein grafts. This study examines the short-term patency (1-3 days) of vein grafts interpositioned to the rat femoral vein. Several factors are studied for their ability to alter the patency rate. The results indicate that patency is difficult to achieve following the creation of a second serial anastomosis (construction of a vein-to-vein graft). Systemic heparin consistently improves patency rates, and trends toward increased patency are seen for reduction in longitudinal tension of the repaired vessel. It is also implied that a deeper understanding of venous hemodynamics and thrombotic events may lead to improved methodologies in the clinical applications of microvenous repairs. These results indicate that rat vein-to-vein grafts may provide a challenging microvascular training model, while introducing the novice microsurgeon to some of the complicating factors encountered with microvascular grafting.