Early endothelial coverage of synthetic arterial grafts: porosity revisited

Synthetic arterial grafts fail because of thrombosis. Rapid endothelial coverage would be expected to generate a minimally thrombogenic surface and reduce the rate of failure. We investigated the possibility that such a lining could be established by transmural capillary ingrowth in polytetrafluoroethylene (30 or 60 micron internodal distance) and Dacron baboon aortoiliac grafts of 4 mm in diameter and 5 to 7 cm in length. All grafts demonstrated endothelial ingrowth from the cut edges of adjacent artery. The central portions of the 30 micron polytetrafluoroethylene grafts were still not healed at 3 months. Two of six Dacron grafts were healed 1 month postoperatively and all were healed at 3 months, whereas all 60 micron polytetrafluoroethylene grafts were healed 2 weeks postoperatively. At early follow-up, islands of endothelium were seen in the middle of the 60 micron polytetrafluoroethylene and Dacron grafts. These observations support the concept that transmural migration of capillaries can provide multiple sources of endothelium and early endothelial coverage of porous synthetic arterial grafts. This response is affected by the porosity and possibly the thrombogenicity of the graft material.