Submucosal tunnel endoscopy: Peroral endoscopic myotomy and peroral endoscopic tumor resection

Figure 1 Peroral endoscopic myotomy stages. A: Mucosal entry after longitudinal incision at the 2-o’clock position; B: Submucosal tunneling. Ectopic innermost longitudinal muscle bundles in front of the circular muscle layer are recognized; C: Palisade vessels at the EGJ inside the tunnel; D: Blue dye at retroversion in the stomach confirms tunnel extension to gastric side; E: The sharp tip of the TT-knife is used to catch circular muscle bundles and then retract them toward the esophageal lumen; F: Longitudinal muscle is identified at the bottom of myotomy site. Longitudinal muscle fibers split each other and a gap is recognized, creating an unintentional, partly full-thickness myotomy; G: Mucosal closure with endoscopic clips. EGJ: Esophagogastric junction.