Vein patching reduces neointimal thickening associated with prosthetic graft implantation

PURPOSE: Modified anastomotic techniques utilizing autogenous vein-cuffs or patches have been devised with the hope of improving prosthetic graft pate ncy. The mechanisms of the presumed improvement in patched anastomoses have never been elucidated and remain speculative. We characterized the healing response of the Taylor vein patch in prosthetic arteriovenous fistulae in a canine model of intimal hyperplasia. METHODS: Six adult dogs underwent placement of bilateral (6 patched, 6 cont rol) 4-mm diameter expanded polytetrafluoroethylene loop femoral artery-vei n fistulae. Serial duplex ultrasound examinations confirmed graft patency u ntil explant at 6 weeks. Differential light microscopy with computerized im age analysis was performed on serial 5-mu m sections. Intimal thickness thr ough the venous anastomosis and outflow veins of Taylor patch and control ( nonpatched) grafts were compared. Cell type-specific immunocytochemical ant ibody stains for smooth muscle cells (a SMC actin) and endothelial cells (v on Willebrand factor) were performed. RESULTS: Eleven of 12 grafts remained patent for 6 weeks, 1 control graft t hrombosed. Mean duplex-derived peak systolic velocities of patched (96 cm/s ec) and control (108 cm/sec) grafts were similar. Microscopy revealed more intimal pannus anastomotic suture line ingrowth in controls (mean thickness = 178 mu m) than Taylor patched grafts (mean 147 mu m, p = 0.0002). Signif icantly less intimal thickening was present in the outflow vein of patched (mean thickness = 90 mu m) versus control grafts (mean 195 mu m, P < 0.0001 ). The intima maintained a single cell layer of vWF + endothelial cells, wh ile the majority of the cells comprising the lesion expressed a SMC actin. CONCLUSION: Perianastomotic pannus is primarily composed of intimal smooth muscle cells. Neointimal thickening is significantly reduced in prosthetic arteriovenous fistulae created with the Taylor vein patch in a canine model . Reduction in perianastomotic intimal thickening may explain the reported clinical improvement in prosthetic bypass graft patency when modified with vein patch techniques. Am J Surg. 1998;176: 601-607. (C) 1998 by Excerpta M edica, Inc.