Objectives: This study applies concurrent magnetic resonance imaging (MRI) and high-resolution manometry (HRM) to test the hypothesis that structural factors involved in reflux protection, in particular, the acute insertion angle of the esophagus into the stomach, are impaired in gastroesophageal reflux disease (GERD) patients.
Methods: A total of 24 healthy volunteers and 24 patients with mild-moderate GERD ingested a test meal. Three-dimensional models of the esophagogastric junction (EGJ) were reconstructed from MRI images. Measurements of the esophagogastric insertion angle, gastric orientation, and volume change were obtained. Esophageal function was assessed by HRM. Number of reflux events and EGJ opening during reflux events were assessed by HRM and cine-MRI. Statistical analysis applied mixed-effects modeling.
Results: The esophagogastric insertion angle was wider in GERD patients than in healthy subjects (+7° ± 3°; P=0.03). EGJ opening during reflux events was greater in GERD patients than in healthy subjects (19.3 mm vs. 16.8 mm; P=0.04). The position of insertion and gastric orientation within the abdomen were also altered (both P<0.05). Median number of reflux events was 3 (95% CI: 2.5-4.6) in GERD and 2 (95% CI: 1.8-3.3) in healthy subjects (P=0.09). Lower esophageal sphincter (LES) pressure was lower (-11 ± 2 mm Hg; P<0.0001) and intra-abdominal LES length was shorter (-1.0 ± 0.3 cm, P<0.0006) in GERD patients.
Conclusions: GERD patients have a wider esophagogastric insertion angle and have altered gastric morphology; structural changes that could compromise reflux protection by the "flap valve" mechanism. In addition, the EGJ opens wider during reflux in GERD patients than in healthy volunteers: an effect that facilitates volume reflux of gastric contents.
Trial registration: ClinicalTrials.gov NCT01053585.