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


METHODS
Primary patency regarding the use of vein collar were re-analyzed in 345 patients from SCAMICOS with Kaplan-Meier life-table technique and Cox proportional hazards regression in a counting process notation to evaluate any interaction between time-period and the effect of a vein collar on the primary patency rate.


RESULTS
No overall effect on primary patency of a vein collar at the distal anastomosis was found irrespective of the site anastomosis. However, during the first 30 days of follow-up the primary patency among the femoro-crural bypasses was 0.87 (0.79-0.95) and 0.72 (0.63-0.83) with and without vein collar respectively. The interaction between vein collar and time-period was not statistically significant (P=0.070) and neither was the Score test for the whole interaction analysis (P=0.091) for the patients with anastomosis to the crural arteries. No such initial differences were found for the patients with anastomosis to the popliteal artery below-knee.


CONCLUSIONS
A clinically relevant but not statistically significant better primary patency during the first 30 days was found for patients with PTFE-bypass to the crural arteries with a vein collar at the distal anastomosis. There were no long-term advantages of the vein collar irrespective of the location of the anastomosis.
Departement of Cardiovascular Surgery, Heart Centre, University Hospital, S-581 85 Linköping, Sweden. fredrik.bg.lundgren@gmail.com
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Lundgren
D000714:Anastomosis, Surgical; D001807:Blood Vessel Prosthesis; D006801:Humans; D007511:Ischemia / Q000601:surgery*; D007866:Leg / Q000098:blood supply*; D011138:Polytetrafluoroethylene; D016032:Randomized Controlled Trials as Topic; D014654:Vascular Patency; D014656:Vascular Surgical Procedures / Q000295:instrumentation*
D011138:Polytetrafluoroethylene