Animal model of bile duct dilatation created with minimally invasive surgery

Development and validation of a novel porcine bile duct dilation model for EUS training

Background and study aims  Image-guided minimally invasive techniques have transformed the management of malignant and benign bile duct obstructions. These evolving techniques are being widely adopted and applied and hands-on training using high quality models is required to improve the proficiency of practitioners. This experimental study aimed to validate an in vivo porcine model created to simulate bile duct dilation for interventional endoscopic ultrasound (EUS) hands-on training curriculums. Materials and methods  Thirty-six porcine models were involved and the procedures were performed in an experimental hybrid operating room under general anesthesia. Animals underwent endoscopic duodenal papilla clipping with several hemostatic metallic clips. After a survival period of 24 to 48 hours, the models with effective intrahepatic and extrahepatic bile duct dilatation were included in the hands-on training. Trainees and faculty were given structured evaluations of the model realism and usefulness. Results  Extrahepatic bile duct and gallbladder dilation was achieved in all 36 of the models, and in 11 of the 36 models, a treatable intrahepatic duct dilatation was achieved. During the hands-on training, EUS-guided biliary drainage, EUS-guided transgastric gallbladder drainage, and EUS through-the-needle microbiopsy forceps procedures were feasible. Overall, 75 % of the experts and trainees evaluated the training as excellent. Conclusions  We present a minimally invasive, reliable and time- effective model of extrahepatic dilation suitable for interventions. The model was less effective for intrahepatic ducts, which should be considered if intrahepatic biliary dilation is required for training.

Novel swine biliary dilatation model with temperature-controlled endobiliary radiofrequency ablation: An effective tool for training in EUS-guided biliary drainage

Background and Objectives:

EUS-guided biliary drainage (EUS-BD) is used as a rescue method after failed endoscopic retrograde cholangiography. However, it is considered a technically challenging procedure. Phantoms and ex vivo biliary dilatation models have been used to enhance the learning of EUS-BD, but they provide a limited level of realism. The aim of this study was to develop a swine biliary dilatation model that uses temperature-controlled endobiliary radiofrequency ablation (EB-RFA) for training in EUS-BD.

Materials and Methods:

Target temperature-controlled (80°C at 7 or 10 W for 60–120 s) EB-RFA was performed on seven pigs. Two weeks after the EB-RFA, EUS examination was performed to confirm biliary dilatation, and EUS-BD was then attempted by performing a hepaticogastrostomy (HGS) or cholecystogastrostomy (CGS).

Results:

Twelve sessions of EB-RFA (11 at the distal common bile duct [CBD] and one at the proximal CBD) were successfully performed on the seven pigs. There were no immediate postprocedural adverse events. Two weeks after the procedures, clinical signs of jaundice were observed in all the pigs. EUS examination revealed massive intrahepatic and extrahepatic biliary dilatations in all the pigs, and EUS-BD was attempted in the same session. HGS was performed on six pigs. Technical success was achieved in five of the six pigs (83.3%). Technical failure in HGS occurred during the stent deployment, and CGS was successfully performed on one pig.

Conclusions:

Our study shows that EB-RFA is an effective minimally invasive method for creating biliary dilatation models. It may be considered suitable for training in EUS-BD.

Development of a swine bile duct dilation model using endoclips or a detachable snare under cap-assisted endoscopy

BACKGROUND

A reproducible large animal model of bile duct dilation for the preclinical testing of new biliary devices and for training endoscopic biliary intervention is required. Surgical methods are mainly used to produce large animal models of biliary obstruction.

OBJECTIVE

To develop an animal model of bile duct dilation using endoscopic methods and to compare the merits of endoclips and detachable snares for the obstruction of major duodenal papillae.

DESIGN

Proof of concept experimental study.

SETTINGS

Animal laboratory.

INTERVENTIONS

Endoscopic clipping of the major duodenal papilla or closure of the major duodenal papilla with a detachable snare.

MAIN OUTCOME MEASUREMENTS

Feasibility, efficacy, and safety of endoscopic methods to develop swine models with bile duct dilation were estimated by degree of dilation at the common bile duct (CBD), intrahepatic duct (IHD), and gallbladder (GB).

RESULTS

All animals survived until the end of the experiment. Clipping of the major duodenal papilla and closure of the major duodenal papilla with a detachable snare were performed successfully in all swine. No technical difficulty or adverse event occurred during the procedures. Biliary dilatations in all animals were observed on cholangiograms (mean Δ% of postprocedural and preprocedural maximum diameters: CBD, 301%; IHD, 223.5%; GB, 34.8%). Degree of bile duct dilation in the snare group tended to be greater (CBD, 367.3%; IHD, 298.3%; GB, 47.8%) than in the endoclip group (CBD, 234.7%; IHD, 148.7%; GB, 21.8%), but this difference was not significant. An analysis of degrees of dilation according to location in the biliary tree showed that the GB was not dilated as well as the CBD or IHD.

LIMITATIONS

Animal model.

CONCLUSION

The 2 endoscopic procedures described are effective and safe for creating a swine model of bile duct dilation and could be helpful for training biliary intervention and for endoscopic biliary studies.

Percutaneous Transcholecystic Biliary Interventions Using Gallbladder Anchors: Feasibility Study in the Swine

The purpose of this study was to report our initial experience with a swine model for biliary interventions by using a percutaneous transcholecystic access after suture anchor of the gallbladder. Telepaque tablets were given to five pigs to opacify the gallbladder. Under fluoroscopy, the opacified gallbladder was punctured percutaneously and three suture anchors were used to fix the anterior wall of the gallbladder to the abdominal wall. Two weeks later, the gallbladder was punctured and access into the distal common bile was obtained through the cystic duct. Balloon expandable stents were deployed into the distal common bile duct. Follow-up cholangiograms were obtained at 1 and 2 weeks. Necropsy was performed after 2 weeks to evaluate the relationship between the gallbladder and abdominal wall. Suture anchor placement was successful in all five pigs. One pig with a deep and highly positioned gallbladder developed fever, anorexia, and vomiting secondary to excessive stretch of the gallbladder. Placement of the guidewire through the extremely tortuous and small cystic ducts proved to be the most challenging step of the procedure. Metallic stents were successfully deployed in all four pigs in which it was attempted. Four animals tolerated the procedures without changes in their clinical conditions and no symptoms. Successful follow-up cholangiograms were performed at 1 and 2 weeks post-stent deployment without complications. All stents remained patent during the follow-up period. Necropsy demonstrated close attachment and adherence of the gallbladders to the antero-lateral abdominal wall in all four animals. Suture anchoring of the gallbladder is feasible in most pigs with superficially located gallbladders. This technique allows a safe and repeat access into the biliary system using a transcholecystic approach.

Development of a swine model for benign stenosis of the bile duct by endoscopic application of intraluminal thermal injury

BACKGROUND

A simple animal model is desirable for the study of endoscopic therapies used in the management of biliary strictures. The aim of this study was to identify a method for inducing benign biliary stenoses in a porcine model by using endoscopic techniques.

METHODS

Endoscopic retrograde cholangiography was performed in 9 swine. Intraluminal injury was applied to the common hepatic duct with graded applications of either a heat probe or a multipolar probe. Cholangiography was repeated at 7-day intervals. If a stricture was not identified by 28 days, injury was created at another site in the common hepatic duct by using a higher energy dose. After a stricture was identified, the animal was killed and bile duct samples were obtained for histopathologic evaluation.

RESULTS

Thirteen thermal injuries were created in the 9 animals. Six of 7 heat probe treatments and 1 of 6 multipolar probe treatments resulted in a stricture (p = 0.025, Fisher exact test). Applications of the heat probe at 10 or 15 J produced a stricture in 6 of 6 cases. All strictures were indistinguishable histopathologically from benign strictures in humans.

CONCLUSIONS

The application of intraluminal thermal injury with a heat probe results in a reproducible animal model of benign biliary stenosis.