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

Abstract

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. Key words: Esophagus ; Stent ; Animal experimentation; Esophageal stenosis