Healing of high-porosity polytetrafluoroethylene arterial grafts is influenced by the nature of the surrounding tissue

The aim of this study was to determine the influence of the nature of the perigraft tissue in the healing pattern of high-porosity polytetrafluoroethylene (PTFE) vascular grafts. Nine-centimeter long segments of unreinforced experimental high-porosity (60 microns) PTFE grafts were placed as abdominal aortic interposition in mongrel dogs. Three grafts served as controls (group A); in five dogs (group B) a 25 x 25 cm piece of devascularized omentum was wrapped around the graft. In five dogs (group C) the omentum with its own vascular supply was completely wrapped around the graft. Animals were killed 4 weeks after surgery. The percentage of thrombus-free area was 31% in group A grafts, 39% in group B grafts, and 79% in group C grafts (p less than 0.01). Scanning electron microscopy showed many confluent areas of endothelium-like cells in the midportion of group C grafts, corresponding to capillary ingrowth. Transmural endothelial migration was more evident in group C grafts. We conclude that the nature of the perigraft tissue influences transmural capillary migration and the endothelialization rate of high-porosity PTFE grafts in dogs. Agents able to increase capillary formation in the perigraft tissue might improve endothelialization of vascular grafts.