AIM: This study aimed to localize the gastric-to-esophageal pH transition point relative to the squamocolumnar junction (SCJ) and esophagogastric junction (EGJ) high-pressure zone in controls and GERD patients. METHODS: Ten controls and 10 GERD patients were studied. Subjects had an endoclip placed at the SCJ prior to a pH catheter pull-through (upright and supine) during concurrent fluoroscopy before and after consuming a standardized meal. Six controls and 6 GERD patients also underwent concurrent manometry. The relative positions of the SCJ, EGJ high-pressure zone, and pH transition points were analyzed. RESULTS: Most controls and GERD patients exhibited an unbuffered acidified segment in the proximal stomach postprandially. The proximal pH transition point was confined distal to the SCJ in control subjects, regardless of posture or meal state. GERD patients exhibited a more proximal pH transition point, extending above the SCJ and EGJ high-pressure zone in the supine position, especially postprandially. However, the high-pressure zone was intact. CONCLUSION: A short segment of unbuffered acidity of unknown volume exists after meals in the proximal stomach. In controls, the unbuffered acidic segment is contained distal to the SCJ while in the GERD patients it extended into and even across the EGJ high-pressure zone. However, this extension through the EGJ in GERD patients occurred in the context of an intact sphincter suggesting that this is best conceptualized as an acid "film" rather than a "pocket." This observation may help explain the propensity of the distal esophageal mucosa to lesions of reflux disease.
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