Hinged Metallo-Plastic Anastomosis Device: A Novel Intraluminal Method for Choledochoduodenostomy

Abstract

Background: Stents are commonly placed in the bile duct to relieve biliary obstruction. The main limitations of plastic stents are their relatively narrow luminal size and occlusion rate. Expanding metal stents last longer but also occlude and are extremely expensive. Creating a permanent fistula of larger diameter between the bile duct and duodenum would be attractive and allow greater drainage of bile. Aim: To invent, prototype and test a new method of forming a biliary duodenal anastomosis. Methods: A novel hybrid metallo-plastic 7F anastomosis device was developed. It consisted of a central ferrous metallic tube sandwiched between 2 tapered flexible plastic end pieces. The stent was hinged on either side of the metal insert so that a magnetic force could form an anastomosis and then the plastic components of the device could deform to fall through the compression anastomosis leaving a fistula above the papilla. These devices were inserted into the bile duct in pigs over a 0.035 inch guidewire with a pusher tube. Chromium plated neodymium iron boron magnets of cylindrical shape with a central lumen were then positioned by passing closed forceps with weak magnetic attraction through the magnets which were held close to the endoscope tip over the intraduodenal portion of the distal bile duct and releasing them so that they exerted compressive ischemic force on the duodenum and bile duct above the papilla. It was possible to remove the magnets using forceps with strong magnetic attraction. Because of the proximal positioning of the biliary papilla in the duodenal bulb it was possible to insert these devices with forward viewing gastroscopes or even colonoscopes in larger pigs in these survival experiments. Results: In preliminary studies a method for stenting the bile duct in pigs was developed and at post-mortem we established that the metal stent and magnet combination exerted sufficient force to cause ischemia. The length of bile duct available for anastomosis by magnetic compression was approximately 3 cms. Seven anastomotic stents were placed in the bile duct of pigs (weight 22-54 Kg). All 4 survival animals were well and eating as soon as they were awake. Anastomoses were successfully accomplished in all survival animals. The supraampullary opening into the bile duct ranged from 5 to 10 mm. Conclusions: A new method for achieving larger diameter biliary drainage by forming a choledocho-duodenostomy above the ampulla. The method seems simple, safe, economical and was accomplished in survival studies without complicalions. Biliary cannulation and device placement was accomplished with both standard forward viewing and side-viewing endoscopes.