A rat esophageal model to investigate stent-induced tissue hyperplasia.

PURPOSE: To evaluate the feasibility of stent placement and the formation of tissue hyperplasia caused by stent placement in a rat esophageal model. MATERIALS AND METHODS: Twenty Sprague-Dawley rats were divided into four groups to assess differing stent diameters and design (group I, 4 mm diameter and a large mesh gap; group II, 5 mm diameter and a large mesh gap; group III, 5 mm diameter and a small mesh gap; and group IV, barbs added to the group III stents). Follow-up, 1-week, and 3-week esophagograms were obtained. Rats were euthanized 3 weeks after stent placement. Microscopic findings were evaluated in groups with an incidence of less than 50% stent migration. RESULTS: Stent placement was technically successful in all rats, and there were no procedure-related complications. No esophageal perforation occurred during follow-up. The incidence of stent migration was 100%, 60%, 40%, and 0% in groups I through IV, respectively. The esophagi with stent migration showed only a small amount of tissue hyperplasia; however, esophagi without stent migration showed gross tissue hyperplasia through the mesh. The microscopic findings were evaluated in groups III and IV. The degree of inflammatory cell infiltration, papillary projection thickness, granulation tissue area, and percentage of the granulation tissue area were higher in group IV than in group III; however, there was no statistical significance. CONCLUSIONS: Esophageal stent placement was feasible in a rat model, and formation of tissue hyperplasia was evident in rats without stent migration. With barbed stents, there was the least incidence of stent migration without esophageal perforation.