Experimental study of the healing process after microvenous graft to microartery

Thirty-nine Wistar female rats, weighing from 250 to 350g, were employed in order to investigate in detail the healing processes of venous grafts interposed in microartery.A segment of the right femoral artery was excised and replaced with the epigastric vein. The grafts were retrieved over a period of time ranging from 4th, 7th, 14th, 28th, 56th and 168 th day postoperatively. The left femoral artery and epigastric vein served as controls. First, patency rate was checked and then changes of the grafted wall were evaluated by light and scanning electron microscope.The following results were obtained:1. Throughout the experimental periods, patency rates were 56. 4%(22/39); that is, 4 th day, 60.0%(3/5), 7 th day, 42.9%(3/7), 14 th day, 80.0%(4/5), 28 th day, 44.4%(4/9), 56 th day, 62.5%(5/8) and 168 th day, 60.0%(3/5) respectively.2. In grafts of 4 days' duration, grafted veins had hyaline degeneration and swelling so that endothelial sloughings were nearly completed on grafts. In grafts of 7 days' one, migrations of new endothelial cells from femoral artery into grafts could be observed, they were almost covered with endothelial cells on 28 th day and were completed on 56 th day postoperatively. The walls of grafted veins started to be replaced by the 14 th day and resulted in fibrous connective tissues at 28 th day. Subintimal hyperplasia, being rich in cellular and fibrous components, appeared around the suture line at 14 th day and could be observed almost all over the graft at 28 th day so that there were no differences of the internal diameter between grafts and femoral arteries at 56 th day.3. Scanning electron microscopic findings nearly coincided with the histopathological ones.In short, it is suggested that there may be no direct relatioships between patency rate and healing process of the venous grafts interposed in microartery.