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

Background: The autogenous vein represents the graft material of choice in crural and pedal bypass surgery. Because of the numerous problems concernin g the graft harvesting and the quality of autogenous vein material an equal ly good allogenous graft is urgently needed. Up to the present times no suc h graft material has been able to achieve the success of vein grafts. Methods: We investigated the knitted polyester prosthesis Terumo PF-V (Teru mo Comp., Japan), diameter 5 mm with outer reinforce, which is characterize d by a new coating of plasmin-treated fibrin. Grafts were implanted as bypa ss into the ligated carotid (n = 10) and femoral arteries (n = 10) of 10 do gs (beagles). As a control 5 mm-ePTFE-prostheses (Impra Carboflo) were impl anted simultaneously on the contralateral side. Results: After 6 months, seven of 20 PF-V-grafts and 8 of 20 PTFE-grafts we re patent. All prostheses presented with good macroscopic healing character istics. In the patent grafts, angiography showed no substantial stenoses. T he histological examination of the material was performed using light micro scopy, transmission polarising microscopy, scanning electron microscopy, an d transmission electron microscopy. Both types of prostheses showed the typ ical pattern of graft healing by migration of mesenchymal cells through the prosthesis, formation of capillaries, and growing of a neointima with endo thelium-like cells. All failed bypass grafts presented with an occluding pr oliferation from the arterial wall into the anastomotic region. Conclusions: Using clinically or histologically evaluation, neither graft d emonstrated superiority over the other. The results indicate that the coati ng plays only a minor role for graft healing if any. For proper graft funct ion, the arterial wall proliferation at the anastomotic region, which is no t dependent on the type of prosthesis, appears to be most important. The ov erall results concerning both types of prostheses were disappointing.