Polytertrafluoroethylene의 직경에 따른 신생내피의 조직학적 변화에 대한 실험적 연구 = Experimental Study of the Histologic Findings of the Neoendothelialization according to Diameter of Polytetrafluoroethylene in Dog

다국어 초록 (Multilingual Abstract)

In synthetic arterial grafts the regeneration and proliferation on the inner surface of graft is a part of the normal healing process. However, there are controversies in the source of these cells and the pattern of proliferation. Many investigators have suggested that endothelium might be derived from arterial sources at the ends of grafts, capillaries growing through the graft matrix from the outside, and endothelial cells can circulate in the blood and settle onto the luminal surface.
The purpose of this study was to investigate the patency rates and the histologic findings of neoendothelialization according to the diameter of polytetrafluoroethylene(PTFE) which is the most widely used for synthetic graft.
Ten mongrel dogs, weighing 20 to 25kg, were used for this study. Under the operating microscope, all grafts were implanted in both femoral arteries of dogs by interrupted end-to-end microanastomosis. They were divided into two groups according to the diameter of implanted PTFE. Each group comprised five dogs. The lengths of implanted PTFE were 20mm in both groups. All implanted grafts were 25㎛ in fibril length and 0.39mm in wall thickness. The internal diameter of graft in group Ⅰ was 3mm and that of graft in group Ⅱ was 5mm. Two grafts of one dog per group were harvested at 1, 2, 4, 8, and 12 weeks after implantation respectively. All PTFE grafts were observed for patency rates and the histologic findings with light microscope and scanning electron microscope.
The results obtained were as follows :
1. The patency rate was higher when the diameter of implanted PTFE was larger than that of recipient vessel, and the patency rate in grafts without infection was higer than that in grafts with infection.
2. Light microscopically, in group Ⅰ, a few cells of neointima is noted at the end of the inner surface of PTFE at 1 week after implantation and the histologic findings could not be observed due to occlusion of grafts at 2, 4, 8, and 12 weeks after implantation. In group Ⅱ, the neointimal lining is advanced across the anastomosis at 1 week after implantation and the histologic findings could not be observed due to occlusion of grafts at 2 and 8 weeks after implantation. At 4 weeks after implantation, neointimal lining was more advanced to the midportion of implanted PTFE. At 12 weeks after implantation, the entire inner surface of implanted PTFE was lined completely by neointima and subintimal tissue.
3. Scanning electron microscopically, in group Ⅰ, the inner surface of implanted PTFE was lined by amorphous fibrin layer at anastomosis site at 1 week after implantationin and the histologic findings could not be observed due to occlusion of grafts at 2, 4, 8, and 12 weeks after implantation. The histologic findings of group Ⅱ were similar to those of group Ⅰ at 1 week after implantation and could not be observed due to occlusion of graft at 2 weeks after implantation. At 4 weeks after implantation, flat layer like normal endothelium was noted at anastomosis site. At 8 weeks after implantation, flat neointima was noted in the midportion of implanted PTFE. However, the inner surface of implanted PTFE was still noted at 12 weeks after implantation.
4. Neoendothelium was noted only in the patent cases with neointimal covering of the inner surface of PTFE.
In conclusion, at 1 week after implantation neoendothelium started to grow from both anastomoses and at 8 weeks neoendothelium was formed in the entire inner surface of implanted PTFE. Because PTFE is not elastic like normal vessel, PTFE with larger diameter than that of recipient vessel is recommended as the grafts fot implantation.