I will be discussing our work on magnet assisted choledocho-duodenostomy. In the way of background the problem with stents is their occlusion rate. Metal stents also occlude and are very expensive. Creation of a fistula between the bile duct and duodenum is therefore an attractive option. The hinged metallic stent consists of a central iron or magnetic core which is sandwiched between two plastic end pieces. The stent is hinged on either side of the insert. Application of a magnetic force in the duodenum results in attraction and attachment between the magnet and the stent and the creation of a compression anastamosis.
The metal stent component is strongly attracted to the duodenal magnet. The stent deforms and folds at its hinges and the collapsed stent then falls through the opening and into the duodenum. The attached stent and magnet are passed through the gastrointestinal tract making endoscopic removal unnecessary. The device was placed in 7 pigs, four of whom were survived between 4 and 7 days. The magnets were inserted over a non-magnetic biopsy forceps which was deployed by withdrawing the forceps through the endoscope. The pigs subsequently underwent duodenoscopy and necropsy.
Biliary-enteric anastomosis were created in the porcine model using a hinged metallic stent. When a magnetic force is applied in the duodenum, this plastic stent deforms at the hinges and falls through the compression anastomosis.
The device is loaded over a guidewire and once biliary cannulation is achieved, it is deployed by advancing a pusher tube over the guidewire.
Neodynium-Boron magnets with a hollow central lumen were inserted over a closed non magnetic forceps which was steered into the animal duodenum following hinged stent placement. The magnets were released adjacent to the intraduodenal bile duct by closing the biopsy forceps and withdrawing them out of the endoscope channel.
The porcine papilla is situated proximally in the duodenal bulb. Forward viewing endoscopes were used. The pig stomach is large making duodenoscopy difficult. These procedures were done without fluoroscopy. Following guide wire placement the hinged metallic stent is placed in the bile duct with the aid of a pusher tube.
Here is an example of another cannulation of the bile duct. Cannulation was performed mainly using sphincterotomes but sometimes with standard 5F ERCP catheters. Here is an example of another hinged metallic stent that's being inserted into the bile duct in the usual fashion. Magnets that were loaded on a biopsy forceps were released once the forceps was adjacent to the intraduodenal bile duct.
Duodenoscopy was repeated 2-7 days later. It revealed the magnets to be firmly adherent to the stent and a deep mucosal depression resulting from erosion and compression into the duodenum was seen
This is an example of an anastomosis created after 2 days. It looks like a large sphincterotomy.
The next example is of an anastomosis created by magnets that were left in for 7 days. Here a large suprapapilary opening can be appreciated. This was easily cannulated with an ERCP catheter. This anastomosis can clearly be seen at post mortem.
This is an example of our best anastamosis which resulted from 2 magnets being left in for 4 days. There is corrosion of the surface of the magnets seen. A large supraduodenal anastamosis was appreciated. The papillary opening is down and to the right of the anastomosis. The anastomosis was very easily cannulated using a 5F ERCP catheter. Here is the post-mortem examination. A forceps could easily be inserted through the anastamosis. A standard diagnostic upper endoscope could be inserted through the anastomosis.
In conclusion then we describe a novel method for creation of a choledocho-duodenal anastomosis. This method appears simple, safe and economical. It was accomplished in survival studies without any complication. This device may represent a possible alternative to conventional stenting in humans.
Priya A. Jamidar, MD, Yale University