Background & Aims: Minimal quantitative information exists on esophageal shortening during peristalsis in the human esophagus. The aim of this study was to ascertain the effect of hiatus hernia on longitudinal muscle-mediated peristaltic esophageal shortening. Methods: Seven volunteers and 11 patients with hiatal hernia had metal clips endoscopically affixed at the squamocolumnar junction and 3-5 cm proximal to it (n = 11). Location of the lower esophageal sphincter and axial clip movement were assessed using concurrent manometry and videofluoroscopy during barium swallows in a supine and upright posture with and without abdominal compression. Results: Three subject groups were defined by the proximity of the squamocolumnar junction to the diaphragmatic hiatus: group 1, ≤0 cm; group 2, between 0 and 2 cm; and group 3, ≥2 cm. Peristaltic esophageal shortening was progressively diminished, re-elongation progressively prolonged, and the degree of contraction observed in the distal esophageal segment reduced with progressive degree of hiatus hernia. There was minimal mobility of the squamocolumnar junction relative to the hiatus with posture or abdominal compression. Conclusions: Longitudinal muscle contraction during peristalsis normally causes transient elevation of the squamocolumnar junction above the diaphragm. Esophageal shortening during primary peristalsis is reduced with increasing degree of hiatus hernia, suggesting that there is diminished opposition of longitudinal muscle contraction from the phrenoesophageal attachments.
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