H.8 Direct Visual Cannulation
Direct Visual Cannulation (DVC) Sphincterotome and DVC-Doppler Sphincterotome
Endoscopic Retrograde Cholangio Pancreatography (ERCP) is an endoscopic procedure performed by Gastroenterologists to treat diseases of the bile duct and pancreas. Examples of bile duct diseases are bile duct diseases include bile duct stones, benign and malignant biliary strictures. ERCP is also performed to evaluate and treat pancreatic diseases including pancreatic duct strictures, pancreatic duct stones and pancreas divisum.
ERCP is a complicated and a difficult endoscopic procedure done using a side-viewing scope. The major ampulla is identified in the second portion of the duodenum. It has a hidden opening which is then accessed with blind probing using a wire or catheter to enter a common channel. Common channel leads to Bile duct is accessed via the sphincter choledochus and the pancreatic duct is accessed via the sphincter pancreaticus. Blind cannulation of either the bile duct or the pancreatic duct is performed based on visual estimation and feel for diagnostic and therapeutic procedures. Fluoroscopy is used to visualize the trajectory of the wire.
Cannulation of the desired duct often requires multiple blind directional probing to “fall” into the desired duct. Repeated blind probing can cause trauma to the sphincter pancreaticus resulting in post ERCP pancreatitis. There is a 5% risk of pancreatitis with any ERCP procedures and especially high risk (almost approaching 40%) in young women. Similarly, blind probing traumatizes the sphincter choledochus causing edema and subsequent inability to cannulate the bile duct. Therefore, prolonged cannulation attempts lead to above complications, prolonged procedure time and exposure to radiation and eventually leading to procedure failure. Prompt cannulation without ampullary trauma of the desired duct (common bile duct and pancreatic duct) for therapy is the key to ERCP success.
Direct Visual Cannulation (DVC) is a novel approach at trying to visualize the common channel opening. Once the common channel opening is visualized, there is a higher probability of cannulating either the common bile duct or pancreatic duct openings. Visualizing the opening will allow for more prompt cannulation of the desired bile duct and pancreatic duct. This will reduce the procedure time thereby decreasing radiation exposure, reduce tissue trauma there by decreasing risk of ERCP related complications, procedure failure rate and possibly also the infection risk.
A DVC Sphincterotome will be created with an ability to image the ampulla and the orifices of the desired duct. The sphincterotome will be 5 Fr at the tip. Boston Scientific has a cholangioscope which has a simplified setup using an image transmission cable integrated with light source and camera. This same technology can be used with the new DVC catheter. Ampulla will be interrogated using air versus normal water insufflation which can potentially help with identification of common channel opening and thereby directing the cannulation.
Additionally, this catheter can also be equipped with doppler ultrasound at the tip to further help with localization. The doppler enabled catheter will be called DVC-Doppler. This sphincterotome can be used if the regular sphincterotome or DVC sphincterotome fails in cannulation of the common channel.