Evaluation of a Second-Generation Tantalum Biliary Stent in a Canine Model

Purpose: To evaluate the safety and feasibility of use of a balloon-expandable tantalum (Tantaflex) stent in the biliary tree in a canine model. Materials and Methods: In this prospective, randomized trial, 10 tantalum stents were placed in eight dogs (two telescoping stents in two dogs), and six Wallstents were placed in six dogs as controls. Stents were deployed into the common bile duct via a cholecystostomy at laparotomy under fluoroscopic and cholangiographic guidance. Two dogs from each stent group were killed at 4,12, and 26 weeks; the two dogs with telescoping stents were killed at 12 weeks. Premortem patency was confirmed cholangiographically. Postmortem stent explants were inspected grossly, and tissues were examined histologically. Bacteriologic evaluation of bile was performed. Results: All 14 dogs survived until they were scheduled to be killed without clinical complication or evidence of jaundice. Patency was demonstrated at terminal cholangiography in 12 of 14 dogs and at explantation in 13 of 14 dogs. One Wallstent placed across the ampulla in a dog killed at 26 weeks became obstructed. In another dog, the presence of a cholelith in the cystic duct precluded filling of the common bile duct from the cholecystotomy. Only mild inflammatory changes were present in the bile ducts. Conclusion: The tantalum stent can be used safely and effectively in the common bile duct in normal dogs. Performance of a clinical trial in humans is supported by findings of this study.