Background: The relationship between body position and the gastroesophageal junction (GEJ) has been subject to intense interest in its role in gastroesophageal reflux disease (GERD). Few studies have looked at the position related changes of the gastroesophageal valve (GEV) in asymptomatic individuals.
Purpose: To define the normal physiology of the GEJ in left lateral decubitus (LLD) and upright position in asymptomatic individuals.
Methods: Ten healthy asymptomatic volunteers with no previous history of GERD were recruited. Patients underwent upper endoscopy, with detailed observation and grading of the gastroesophageal valve (Hill Grade 1-4; 1 = normal closed valve, 4 = open valve, associated hiatus hernia) in both LLD and upright positions. Patients underwent high resolution manometry, with wet swallows performed in LLD and upright positions. A Bravo pH probe was placed in the distal esophagus and used to perform 48-h pH studies in all patients.
Results: Four out of 10 patients were noted to have abnormal 48 h pH studies (DeMeester score >14.7). Endoscopically, there was an overall increase in mean Hill Grade when patients were moved from LLD to upright position (1.6, 2.3, p = 0.04, respectively), with no significant differences between normal and abnormal pH patients. In the abnormal pH group, on endoscopy, 75% were found to have prolonged opening of the GEV on passive retroflexed observation in LLD position, compared with 16.7% of normal pts (p = 0.1). Manometrically, this was correlated with lower mean LES resting pressures and shorter intra-abdominal LES length for the abnormal pH patients in all positions compared to normals. As well, for the abnormal pH group, LESP trended down slightly when moved from LLD to upright position (11.2 vs. 8.0 mmHg, respectively; p = 0.3).
Conclusions: In normal individuals, the GEV exhibits a temporary weakening when moved from LLD to upright position. However, the normal GEV is able to maintain LESP in upright position. In contrast, in patients with early GERD, a greater degree of valve incompetence at the GEJ is seen. This is correlated manometrically with a trend toward shorter LES length and lower LESP when moved from LLD to upright position. This upright incompetence of the GEV may be one of the earliest manifestations in GERD. Proper evaluation of the GEV should include endoscopic evaluation in both recumbent and upright positions. Further studies are needed to evaluate the corresponding changes of the GEV in varying degrees of symptomatic GERD.