Introduction: Permanent disruption of the clasp and collar sling muscle fibers that comprise the distal aspect of the lower esophageal sphincter is believed to predispose patients to GERD. However, little is known about the effect of body position on hiatal anatomy in patients with GERD. We propose that body position has a significant impact on esophagogastric junction anatomy, and that investigations of these differences may enhance our understanding of the pathophysiology underlying GERD.
Methods: Fifty-three patients with PPI responsive heartburn and/or regurgitation underwent upper endoscopy in the upright and supine positions. All patients having undergone prior hiatal surgery were excluded. Digital images of the cardia were obtained in both positions under a set insufflation volume. Gastric cardia circumference measurements were performed by an observer blinded to position using validated software. Measurements were compared using paired t-test with results presented as mean cardia circumference ± SEM.
Results: The gastric cardia circumference for patients in the supine position was 53.1 ± 2.3 mm. These values decreased to 32.9 ± 1.4 in the upright position (p<0.01). A subgroup of patients with biopsy proven BE (N=18) had increased cardia circumferences of 58.2 ± 4.2 mm for CSE and 37.1 ± 2.4 mm for SCE with a mean difference of 21.1 ± 4.4 mm (p<0.01).
Conclusion: Body position has a significant impact on the anatomic configuration of the esophagogastric junction as indicated by changes in the gastric cardia circumference. Whether this effect is directly related to positional changes in the crural diaphragm diameter or the cardia itself is unknown and requires further study.