A novel postgraduate endoscopic course using a large animal model of secondary Crohn's disease stricture.

BACKGROUND: The increasing complexity of advanced endoscopic techniques places a high demand on the endoscopist's expertise. Thus, live porcine models have been more frequently used for training. We briefly describe a hands-on postgraduate endoscopic course regarding a novel method of treatment of anastomotic strictures in a porcine model. METHODS: The porcine model of Crohn's disease anastomotic stricture with two artificial side-to-side ileo-colonic anastomoses was used. Participants performed endoscopic stricturotomy under supervision at one of two equipped endoscopic stations. Available animals were endoscopically re-examined 3 months after the course. RESULTS: Twelve anastomoses were prepared for the course. Eleven circumferential stricturotomies together with horizontal cut and clip placement were conducted. All anastomoses were passable for the scope after the procedure, and no case of perforation or bleeding occurred. All anastomoses available for re-examination remained passable for the endoscope after 3 months. CONCLUSION: We successfully organised the first endoscopic hands-on course for the training of endoscopic stricturotomy on a large animal model.

Surface Microdialysis for Detection of Colorectal Anastomosis Ischemia-An Experimental Study.

BACKGROUND: Inadequate blood supply is one of the major risk factors for anastomotic leak after low anterior rectal resection. Early detection of ischemia might predict complicated healing and enable anastomotic salvage, which is associated with better outcomes. A microdialysis offers a real-time evaluation of adequate bowel perfusion through monitoring of tissue metabolism. In this experimental study, we assessed the role of microdialysis in detecting early ischemia after colorectal anastomosis. MATERIALS AND METHODS: Colorectal anastomosis was performed in six miniature pigs. A microdialysis catheter was placed on the bowel serosa 5 mm proximal to the anastomosis. Metabolic changes were monitored hourly before and after initiating ischemia, which was induced by ligation of the inferior mesenteric artery and skeletonization of the mesocolon. RESULTS: Significant increase in tissue levels of lactate was detected after 60 min of ischemia (13.6 [10.4-16.1] versus 6.75 [1.8-9.6] mmol/L at baseline; P < 0.005). The lactate/pyruvate ratio increased accordingly. The concentration of glycerol increased significantly after 2 hours-from a baseline value of 29.5 (3-84) to 125 (79-201) mmol/L (P < 0.005). The decrease in glucose levels was also significant after 60 minutes-0 (0-0.2) versus 4.7 (3.3-6.8) mmol/L at baseline. However, its values started to decline before ischemia. CONCLUSIONS: Surface microdialysis can detect ischemic changes early and may be a promising method in postoperative monitoring of colorectal anastomosis.

Novel porcine model of Crohn's disease anastomotic stricture suitable for evaluation and training of advanced endoscopic techniques.

BACKGROUND AND AIMS: Currently, treatment options in postsurgical recurrence of stricturing Crohn's disease (CD) are limited. However, development of new invasive endoscopic techniques in clinical practice has safety constraints. The aim of this study was to create a large animal model of anastomotic stricture with CD properties to enable development of new techniques and training. METHODS: A side-to-side ileocolonic anastomosis was created in a modified Roux-en-Y manner with bowel continuity preserved. Two weeks after surgery, we began endoscopic submucosal injections of phenol/trinitrobenzenesulfonic acid solution. This solution was injected every 2 weeks in each quadrant of the anastomosis until development of a stricture. The anastomosis site was assessed endoscopically 2 weeks after the last application (baseline) and then every 2 months until month 6. Endoscopically nonpassable strictures were treated with balloon dilation, endoscopic stricturotomy, and stent placement to confirm the feasibility of such interventions. RESULTS: Nineteen minipigs were included with no postoperative adverse events. After a mean of 4.4 ± .7 injection sessions with 10.5 ± 3.0 mL of the solution, anastomotic strictures were created in 16 pigs (84.2%). Mean diameter of the strictures at baseline was 11.6 ± 2.2 mm. The strictures were inflamed, and the endoscope could not pass. Follow-up was successfully completed in 15 animals (79.0%) with the mean deviation from the initial diameter in every measurement of -.02 ± 2.26 mm (P = .963) and a mean final diameter of 11.7 ± 3.4 mm. The histopathologic evaluation revealed the presence of submucosal fibrosis, chronic inflammation, and microgranulomas. All strictures were amenable to endoscopic therapeutic interventions. CONCLUSIONS: We developed a novel, reproducible porcine model of anastomotic stricture with histologically verified changes mimicking CD and stable diameter for more than 6 months. It is suitable for further endoscopic interventions.

A new experimental model of calculous cholecystitis suitable for the evaluation and training of minimally invasive approaches to cholecystectomy.

BACKGROUND: Novel, less invasive approaches such as single-incision laparoscopic cholecystectomy or natural orifice transluminal endoscopic surgery require preclinical evaluation and training. Therefore, there is a need for an experimental model closely mimicking the clinical situation. The aim of our study was to create an experimental model of calculous cholecystitis in a large laboratory animal and test its feasibility for the evaluation of different techniques of cholecystectomy. METHODS: In 11 laboratory pigs, gallstones were placed inside the gallbladder laparoscopically. Levels of inflammatory markers-leucocytes (WBC), C-reactive protein (CRP) and interleukin 6 (IL-6)-were monitored on the postoperative days (POD) 1, 2, 3, 7 and 30. Abdominal ultrasound was performed 2 and 4 weeks after the operation. Four weeks after the lithiasis induction, laparoscopic cholecystectomy was performed. The control group consisted of ten healthy animals in which a cholecystectomy was performed. The pigs were monitored for 30 days after surgery. All removed gallbladders were assessed histologically. RESULTS: The induction of lithiasis took 42 (35-52) min with no morbidity and mortality. The values of WBC, CRP and IL-6 increased significantly (vs. baseline) on POD 1, 2 and 3 (p < 0.05) and then normalised. Ultrasonography confirmed the presence of chronic calculous cholecystitis in all cases after 4 weeks. Laparoscopic cholecystectomy was significantly longer in animals with lithiasis, 63 (42-91) versus 46 (31-62) min (p = 0.018). Perioperative gallbladder wall perforation was significantly more frequent in the model group (8/11 vs. 1/10; p = 0.04). In contrast to healthy animals, all gallbladders with stones showed histological signs of chronic inflammation. CONCLUSIONS: A new animal model of calculous cholecystitis was created. Laparoscopic cholecystectomy was more technically difficult compared to operating on a healthy gallbladder. This model may be a suitable tool for effective preclinical training and also for the evaluation of different techniques of cholecystectomy.