Prototype stent: In vivo swine studies in the biliary system

PURPOSE: To evaluate the safety of implantation and the biocompatibility of a new balloon-expandable stent in the biliary system of the swine model. MATERIALS AND METHODS: Thirty stents, varying in diameter from 4 mm to 12 mm and in length from 2 cm to 6 cm, were placed in the bile ducts of 10 microswine. After implantation, one-third of the animal subjects were killed at 2 months and the rest, at 6 months, All animals underwent premorbid cholangiography. Stents were pressure fixed, harvested, and encased in methacrylate. Specimens were then sectioned with a diamond saw, prior to staining, Individual specimens were photographed for visualization of the histologic reaction. RESULTS: Technical success (implantation) was 100%, All stents were widely patent at 2-month and 6-month follow-up. Histopathologic study demonstrated a very thin epithelial hyperplasia that formed between stent wires. This did not cover the stent wires. CONCLUSION: This new stent is safely implantable and demonstrates minimal tissue reaction in the biliary system of the swine, when compared with other metallic biliary stents.