三种食管支架覆膜对支架置入术后再狭窄影响的研究

Influence of metal stent membrane on esophageal re-stenosis after stent placement

目的探讨3种覆膜支架置入后引起的食管黏膜局部形态学及病理学变化特点。方法将16只新西兰大白兔分为4组，每组4只。A组置入硅橡胶覆膜镍钛合金支架，B组置入有裙边的硅橡胶覆膜镍钛合金支架（作为对照组），C组置入有裙边的聚四氟乙烯覆膜镍钛合金支架，D组置入有裙边的聚氨酯覆膜镍钛合金支架。X线辅助下置入支架后，各组分别于术后2、4、6、8周处死1只动物，取出置架部位的食管组织分别行肉眼形态、光学显微镜、电子显微镜观察及免疫组化法检测。结果随着支架置入时间的延长，同一组内食管壁厚度相应增加，支架两端增生严重，局部肉芽组织形成及纤维化，管腔狭窄。以B组作为对照，C组相应部位同一观察时点食管壁的厚度较薄（P〈0．05）。术后2、4、6、8周光镜下观察食管黏膜炎症变化，发现A组重于B组，C组轻于B组，D组与B组相似。A组术后2周少量PCNA阳性表达，术后4周明显表达，术后6周少量表达；B、C、D组术后4、6周明显表达，术后8周少量表达。结论再狭窄主要表现为肉芽组织形成和纤维化，发生于支架两端，下端炎性反应重于上端。不同覆膜食管支架置入后引起的食管黏膜炎症变化有所不同，其中聚四氟乙烯组支架引起的黏膜炎症反应最轻，对局部食管壁的损伤出现的最晚。

Objective To explore the pathologic and morphologic changes of local esophageal mueosa after placement of metal stents covered with three different kinds of membranes. Methods Sixteen healthy adult rabbits were randomly divided into 4 groups to receive silicone rubber-covered esophageal stents （group A, n =4）, silicone rubber-covered stents with fringe （group B, n=4, control group）, polytetraflu- oroethylene-covered stents with fringe （ group C, n = 4 ） and polyurethane-covered stents with fringe （ group D, n =4）, respectively, under X-ray guidance. One rabbit from each group was sacrificed at 2,4,6 and 8 weeks after stent placement and the esophageal tissue adjacent to the stent was collected and analyzed by gross observation, light microscopy, electron microscopy, and immunohistochemical examination. Results The thickness of esophageal wall increased with the duration of stent placement in each group. Tissue prolif- eration occurred at both ends of the stents, with local granulation, fibrosis and stenosis. The esophageal wall of animal in group C was thinner than that in group B （ P 〈 0. 05 ）. Compared with that in group B, esoph geal mucosal inflammation in group A was more severe, while that in group C was milder, and that in group D was similar. In group A, PCNA was slightly expressed at 2 and 6 weeks, and markedly expressed at 4 weeks after stent placement, while in groups B, C and D, PCNA was markedly expressed at 4 and 6 weeks, and slightly expressed at 8 weeks after stent placement. Conclusion Esophageal re-stenosis after stent placement is characterized by granulation and fibrosis at both ends of the stent, with inflammation at distal end more severe than that at proximal end. Different stent membrane stimulates different levels of inflammation in esophageal mucosa, which is the mildest by polytetrafluoroethylene membrane and occurred at the latest time.