Submucosal Endoscopy with Mucosal Resection (SEMR): A new hybrid technique of endoscopic submucosal dissection in the porcine rectosigmoid colon

Kohei Takizawa, MD, Christopher J Gostout, MD, Mary A Knipschield

Developmental Endoscopy Unit, Division of Gastroenterology and Hepatology, Mayo Clinic, USA

INTRODUCTION: In Western countries ESD has not prevailed due to training issues and a target patient population. We have recently developed a new hybrid technique, SEMR which combines the mucosal safety valve flap (SEMF) method with traditional ESD technique for undermining the flat and laterally spreading colorectal polyp. The SEMF hybrid technique may be easier and safer. The aim of this study was to evaluate the feasibility of SEMR for the removal of large areas of the mucosa in the porcine rectum and colon.

METHODS AND PROCEDURES: All animals underwent general anesthesia with endotracheal intubation. Targeted sites in the rectum and the distal colon were marked by spot coagulation. Submucosal fluid cushions (SFC) were created using 0.83% hydroxypropyl methylcellulose with added Mesna (sodium 2-sulfanylethanesulfonate), followed by a circumferential mucosal incision (IT knife, Olympus America, Center Valley, Pa). After isolation of the targeted mucosa, balloon dissection was initiated. We used two balloon types, a blunt-tip prototype compliant balloon (4-8 mm, Fast Forward Medical, Minneapolis, Mn) was used only in first 3 pigs and blunt tipped ERCP stone extraction balloons (8-11.5 mm, Model No. B7-2LA, Olympus America, Center Valley, Pa.) were used in other 26 pigs. The Balloon was inserted deep into SFC and repeatedly pulled back toward the endoscope tip to disrupt the submucosa and expose the muscularis. Residual strands of submucosa were cut. Dissections were rated by using a visual analog scale ranging from 0 (easy complete dissection) to 5 (failed dissection). This study underwent Institutional Animal Care and Use Committee (IACUC) review, assignment of animal numbers for the study, and approval.

RESULTS: Twenty-nine domestic cross-breed pigs with preprocedure weights of 58.9 ± 6.2 kg were used. Total 58 lesions (29 in rectum and 29 in distal colon) were resected using SEMR technique. The complete resection rate was 94.8% (55/58). There were three incomplete resections, 2 due to an errant site location too proximal in the colon where we could not create a robust SFC and 1 due to the floppy prototype balloon catheter tip. The median resected size was 6.0 cm (range 2.0-8.6). The median procedure time was 25 min (8-104). Dissection difficulty ranged from 0 to 5, with a median of 1 and mean of 1.5 ± 1.5. The perforation rate was 1.7% (1/58), a single uninflated balloon catheter perforation of the MP occurred in a dissection site just above 20 cm from the anus with a suboptimal fluid cushion. There were no mucosal perforations and no other major complications.

CONCLUSIONS: Large mucosal target sites in the rectum and distal colon of the pig could be safely removed en bloc by means of a hybrid technique, SEMR, combining elements of ESD with our SEMF method.

Session: Podium Presentation

Program Number: S052

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