Effect of porosity on small-diameter vascular graft healing

Experimental studies have reported that complete healing of small-diameter expanded polytetrafluoroethylene (ePTFE) grafts occurs only if the porosity of the graft is increased, thereby allowing ingrowth of perigraft capillar ies yielding endothelial cells. This study investigates the effects of vari ed graft porosity on the healing characteristics of 2-mm internal diameter (ID) ePTFE grafts interposed in the rabbit common carotid artery. Four grou ps were evaluated: Group A (n = 8) standard (30-mu m pores) ePTFE grafts; G roup B (n = 8) increased porosity (60-mu m pores) ePTFE grafts; Group C (n = 8) standard ePTFE; and Group D (n = 8) 60-mu m ePTFE external graft surfa ce was externally coated with an impermeable layer of polyurethane. Patency was 100% for all groups at 8 weeks. At explantation, the neointima was com posed of primarily modified smooth muscle cells. Endothelial cells were onl y identified at the perianastomotic region using the endothelial cell-speci fic antibody CD31. The impermeable external polyurethane coating of ePTFE g rafts had no effect on neointima formation, regardless of porosity. (C) 200 0 Wiley-Liss, Inc.