Healing characteristics of small-calibre vascular prostheses coated with plasmin-treated fibrin--an experimental study.

ABSTRACT

BACKGROUND: The autogenous vein represents the graft material of choice in crural and pedal bypass surgery. Because of the numerous problems concerning the graft harvesting and the quality of autogenous vein material an equally good allogenous graft is urgently needed. Up to the present times no such graft material has been able to achieve the success of vein grafts. METHODS: We investigated the knitted polyester prosthesis Terumo PF-V (Terumo Comp., Japan), diameter 5 mm with outer reinforce, which is characterized by a new coating of plasmin-treated fibrin. Grafts were implanted as bypass into the ligated carotid (n = 10) and femoral arteries (n = 10) of 10 dogs (beagles). As a control 5 mm-ePTFE-prostheses (Impra Carboflo) were implanted simultaneously on the contralateral side. RESULTS: After 6 months, seven of 20 PF-V-grafts and 8 of 20 PTFE-grafts were patent. All prostheses presented with good macroscopic healing characteristics. In the patent grafts, angiography showed no substantial stenoses. The histological examination of the material was performed using light microscopy, transmission polarising microscopy, scanning electron microscopy, and transmission electron microscopy. Both types of prostheses showed the typical pattern of graft healing by migration of mesenchymal cells through the prosthesis, formation of capillaries, and growing of a neointima with endothelium-like cells. All failed bypass grafts presented with an occluding proliferation from the arterial wall into the anastomotic region. CONCLUSIONS: Using clinically or histologically evaluation, neither graft demonstrated superiority over the other. The results indicate that the coating plays only a minor role for graft healing if any. For proper graft function, the arterial wall proliferation at the anastomotic region, which is not dependent on the type of prosthesis, appears to be most important. The overall results concerning both types of prostheses were disappointing.