Prosthetic microvenous grafting into the femoral vein of the rat; considerations concerning the anastomotic technique.

The sequential thrombotic events which occur after implantation of microvenous prostheses prepared from a polyurethane-based material (I.D. 1 mm, length 5 mm, n = 36) into the rat femoral vein by means of the conventional end-to-end suture technique were evaluated by direct inspection and by scanning electron microscopy during the first 24 postoperative hours. Thrombus formation started at the anastomotic sites on the exposed collagenous vessel wall tissue and increased with increasing postoperative time intervals, leading to complete occlusion of the prostheses after 30 minutes of implantation. As a result of these findings, 8 more microvenous prosthetic implantations were performed with the sleeve anastomotic technique and evaluated after 24 hours. Six of these prostheses were patent with only minimal exposure of collagenous tissue at the anastomotic sites and subsequently minimal thrombus accumulation. Two prostheses left in situ and evaluated after 3 weeks were then still patent and completely endothelialised. Based upon the present study, we recommend the sleeve anastomotic technique for implanting synthetic microvenous prostheses because this technique prevents extensive exposure of collagenous vessel wall tissue at the anastomoses, thus leading to less thrombus accumulation and subsequently to a higher patency rate.