The vein collar: an anastomotic servant or a patency promoter? Re-analysis of a randomized trial

Randomized studies evaluating the effect of a vein collar at the distal anastomosis of PTFE-grafts show conflicting results. The study of the Joint Vascular Research Group (JVRG) of UK found improved primary patency while the Scandinavian Miller Collar Study (SCAMICOS) found neither any effect on patency nor on limb salvage after bypass to below-knee arteries. It has been discussed whether the questioned positive effect of a vein collar is due to technical advantages when the anastomosis is made rather than on a positive influence on the long-term effect by less pseudointima formation.