Mechanisms of Acid Reflux and How Refluxed Acid Extends Proximally in Patients with Non-Erosive Reflux Disease

Abstract

Background/Aims: The mechanisms that cause acid reflux in patients with non-erosive reflux disease (NERD), including those that determine how acid extends proximally, are not yet clear. Methods: Concurrent esophageal manometry and pH monitoring were performed for 3 h after a meal in 13 patients with NERD, 12 with mild reflux esophagitis (RE), and 13 healthy subjects (HS). Results: Transient lower esophageal sphincter (LES) relaxation (TLESR) was the major mechanism of acid reflux in all three groups. LES pressure did not differ between the groups. At 2 cm above the LES, there were no differences between the three groups in the number of TLESR-related acid reflux episodes, rate of TLESRs and rate of acid reflux during TLESR. However, at 7 cm above the LES, the rate of acid reflux during TLESRs was significantly higher in patients with NERD (mean ± SEM 42.3 ± 4.8) than in those with mild RE (28.0 ± 3.8) and HS (10.8 ± 2.5). Conclusions: TLESRs are the sole motor events underlying acid reflux episodes in patients with NERD. Acid extends proximally more readily in patients with NERD than in HS and those with mild RE.