These are our disclosures. Gastric peroral endoscopic myotomy, or GPOEM, is emerging as a treatment option for patients with gastroparesis. Unlike esophageal or EPOEM, where the direction of the submucosal tunnel is straight down, creating a submucosal tunnel in the gastric antrum can be more directionally challenging. We describe a novel navigational tunneling method which guides the submucosal dissection in the direction of the pylorus and helps to identify the pyloric landmarks. Six consecutive patients underwent GPOEM for the treatment of symptomatic gastroparesis confirmed by prolonged gastric emptying study. Mucosal caudary markings were made to outline the tunnel, starting 3 to 4 centimeters proximal to the pylorus. Navigational tunnel was created by submucosal injection of carboxymethylcellulose combined with methylene blue, starting right at the pylorus and extending backwards to the incision point. Submucosal dissection was performed by following the prior submucosal injection straight to the pylorus. Clinical Implications. The navigational tunnel technique provides a visual path for the submucosal dissection straight to the pylorus. It may also help to identify the pylorus by accentuating the circular muscle structure with blue coloring on the duodenal side. These attributes may improve the efficiency of the submucosal tunnel dissection, which is the most time-consuming part of the procedure. Case 1 is a 39-year-old female with a past medical history of laparoscopic hernia repair with a diagnosis of post-surgical gastroparesis. Her symptoms include nausea, retching, vomiting, gastric fullness, satiety, bloating, and distention with a GCSI score of 28. Her gastric emptying study showed 52% retained food at 4 hours. On endoscopy, the pylorus is snug and difficult to traverse. The navigational tunnel technique begins with cautery to mark the perimeter of the tunnel in order to guide the subsequent injection. Next, using a 25-gauge needle, submucosal injection of carboxymethylcellulose 0.5% with methylene blue starts right at the pylorus, which will serve to later identify the pyloric muscle from within the tunnel. Subsequent contiguous injections are made, backtracking to the proximal markings, which represent the entry point of the tunnel. After forming the navigational submucosal tunnel, we are ready to start the mucosal incision. Using a cautery knife with built-in high-pressure water injection, the mucosotomy is completed. The scope is then eased into the preformed navigational tunnel. Using a special coagulation mode, the knife is used to dissect submucosal tissue as well as coagulate submucosal vessels. Minimal injection of additional water is necessary within the preformed tunnel. One merely follows the direction of the prior blue injection and it leads you straight to the pylorus. Perhaps the two greatest angst in doing a G-POM is 1. 1. Making sure you are tunneling in the right direction towards the pylorus and 2. Knowing when you have actually arrived. The pylorus is readily identified here. As demonstrated here, there was no need to repeatedly come out of the tunnel to make sure you were not straying off course. A single confirmation is made by visualizing the submucosal fluid extension onto the duodenal side. Then re-entering the tunnel, we are ready for the pyloro myotomy. Using a thinner right angle knife, the myotomy is carefully performed using a raking technique. This minimizes the risk of violating the peritoneum. For a more thorough and robust opening, I prefer doing a double myotomy. After doing 7 o'clock, here I am cutting at 5 o'clock, carefully extending it down to the serosal layer. Here is 7 o'clock, here is 5 o'clock. I also like to extend one of the myotomy approximately 1.5 cm approximately in the pre-pyloric antrum. Now I come out of the tunnel and confirm minimal resistance to scope passage through the gastric outlet. The final step is closing the mucosal incision, which can be done by either suturing or, in this case, using endoscopic clips. This slide summarizes the 6 patients' tunnel appearance and angulation. Patients 2, 4, and 5 had steep angulation due to J-shaped stomachs. This summarizes the results of the 6 consecutive patients. The injection time to create the navigational tunnel averaged 2 minutes and 42 seconds. The myotomy time, whether single or double, averaged 6 minutes and 54 seconds. Most importantly, despite variability in stomach anatomy and angulation and prior Botox injections, the average tunneling time was only 15 minutes and 36 seconds. In conclusion, this novel navigational tunneling technique appears to guide and facilitate the submucosal dissection portion of the GPOME procedure, including in J-shaped stomachs. It may increase efficiency by decreasing the need to repeatedly come out of the tunnel to check direction and prevent non-productive wandering. And finally, it may also help identify the pyloric ring within the tunnel.

gastric peroral endoscopic myotomy

GPOEM

navigational tunneling technique

gastroparesis treatment

pyloric landmarks