Background and AimOne of the challenges during peroral endoscopic myotomy (POEM) is ensuring the appropriate length of myotomy on the gastric side. To determine the appropriate distal end of the gastric myotomy, we focused on the two penetrating vessels (TPVs) found in the gastric cardia during POEM. In the present study, we evaluated whether the TPVs could serve as an accurate indicator of the appropriate distal end of the gastric myotomy.MethodsAll patients who underwent POEM between March and August 2016 were included for this study. When making the submucosal tunnel in the 5 o'clock direction into the stomach, two vessels penetrating through the circular muscle along the edge of oblique muscle in the cardia can be exposed. We designated these two vessels as TPVs. The myotomy was extended until the second TPVs was exposed. The anal end of the submucosal tunnel was confirmed by the double‐scope POEM technique, and the length from the gastroesophageal junction to the anal side end of the myotomy was measured by the scale on the endoscope.ResultsAmong 37 patients who underwent myotomy in the 5 o'clock position, TPVs were found in 34 patients (91.2%). Sufficient submucosal tunneling on the gastric side was confirmed by the double‐scope POEM technique in these 34 patients. Median length of the gastric myotomy was 3.0 cm (range 2–4 cm).ConclusionTPVs appears to be a simple and reliable indicator to determine the appropriate distal end of myotomy.