应用Gore-Tex人造血管重建颈总动脉的实验研究

目的　观察人造血管移植后不同时间的通畅率和组织病理学变化 ,探讨人造血管移植失败的原因。方法　 3只健康成年山羊作为实验对象 ,手术切除 2 cm颈总动脉 ,以口径 4m m的 Gore- Tex人造血管进行桥接。 3只动物的 6侧颈部随机分为 A、B两组 ,各含 3条动脉。A组的近、远心端均为端 -端吻合术 ,B组的近心端为端 -侧吻合术 ,远心端为端 -端吻合术。移植术后 1周 ,以激光多普勒血流仪监测移植血管通畅情况 ,并择例行颈动脉造影术。术后 2周、3月、6月分期切取标本 ,观察人造血管不同时间的通畅率。标本经处理后分别作光镜、透射电镜和扫描电镜检查。结果　 A、B两组人造血管于术后 2周、3月和 6月时的通畅情况分别为 1/1,0 /1,0 /1和 0 /1,1/1,1/1,其差别无显著意义 (χ2 =0 .1414,P=1.0 )。组织病理学检查显示 ,植入后 2周 ,人造血管内壁有少量内皮细胞覆盖 ,结缔组织外膜形成。植入后 3月 ,吻合口处动脉内膜增生 ,向人造血管中段移行 ,延伸长度距吻合口约 6 mm。人造血管新内膜形成不均一 ,部分区域出现过度增生。吻合后 6月 ,扫描电镜显示内皮细胞覆盖不完全 ,延伸长度距吻合口8m m。结论　以人造血管修复颈动脉缺损是可行的 ,但自然内皮化相对有限 ,而且新内膜形成不均。血栓形成和新内膜过度增生 ,均?

RECONSTRUCTION OF THE COMMON CAROTID ARTERY WITH GORE-TEX VASCULAR GRAFTS IN GOATS

Objective To establish a procedure for bridging carotid artery defect with artificial vascular grafts, to estimate the patency rate and histopathologic changes at different times after transplantation, with the aim of understanding the causes of graft failure and providing a basis for clinical use.Methods 3 healthy adult goats were used as the experimental models. A segment of the common carotid artery 2cm in length was removed and bridged with Gore Tex vascular graft (4mm in diameter and 2 cm in length). The six necks of the three animals were divided into A and B group randomly. In Group A, both cut ends of the artery were anastomosed end to end with the vascular graft. In Group B, the proximal end of the artery was anastomosed end to side with the graft. The patency of the graft was monitored with Laser Doppler Flowmeter within one week and carotid angiography was performed in selected animal. The vascular graft with anastomotic sites were harvested at 2 weeks, 3 months and 6 months after transplantation, respectively. The patency rate was recorded at different times. The surgical fresh specimens were prepared and subject to histopathologic evaluation under light microscope, scanning electron microscope and transmission electron microscope. Results One graft in Group A was patent at 2 weeks, 2 occluded at 3 months and 6 months. Two grafts in Group B were patent at 3 months and 6 months; One occluded at 2 weeks. The patency rate of Group B was higher than that of Group A, but no significant difference was found between the two groups(χ 2=0.1414, P =1.0). Histopathologic examinations showed 2 weeks after implantation, a small amount of endothelial cells were covered on the inner wall of the graft, and a layer of connective tissues were around the external wall of the graft, which was similar to the adventitia. Three months after implantation, arterial intimal hyperplasia was seen adjacent to the anastomoses, and migrating toward the central portions of the grafts. The repopulation distance from the anastomotic sites was 6mm. The neointimia of the graft was unhomogeneous, excessive proliferation was noted at some areas. Six months following implantation, scanning electron microscope demonstrated incomplete repopulation of the endothelial cells. The resurfacing distance from the anastomoses was about 8 mm. Conclusion Reconstruction of carotid artery with Gore Tex vascular graft is relatively reliable, but a 100% patency rate can not be achieved. The key for successful use of artificial vascular graft to bridge carotid artery defect lies in its endothelialization. Unfortunately, natural endothelialization is limited, and the neointimization is unhomogeneous. Thrombosis and excessive proliferation of the neointima can both result in failure of vascualr grafts. The problem of endothelialization of artificial vascular graft remains to be solved.