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BACKGROUNDHiatus hernia and lower oesophageal sphincter hypotension are often viewed as opposing hypotheses for gastro-oesophageal junction incompetence.AIMSTo examine the interaction between hiatus hernia and lower oesophageal sphincter hypotension.METHODSIn seven normal subjects and seven patients with hiatus hernia, the squamocolumnar junction and intragastric margin of the gastro-oesophageal junction were marked with endoscopically placed clips. Axial and radial characteristics of the gastro-oesophageal junction high pressure zone were mapped relative to the hiatus and clips during concurrent fluoroscopy and manometry. Responses to inspiration and abdominal compression were also analysed.RESULTSIn normal individuals the squamocolumnar junction was 0.5 cm below the hiatus and the gastro-oesophageal junction high pressure zone extended 1.1 cm distal to that. In those with hiatus hernia, the gastro-oesophageal junction high pressure zone had two discrete segments, one proximal to the squamocolumnar junction and one distal, attributable to the extrinsic compression within the hiatal canal. Inspiration and abdominal compression mainly augmented the distal one. Simulation of hernia reduction by algebraically summing the proximal segment pressures with the hiatal canal pressures restored normal maximal pressure, radial asymmetry, and dynamic responses of the gastro-oesophageal junction.CONCLUSIONSHiatus hernia reduces lower oesophageal sphincter pressure and alters its dynamic responsiveness by spatially separating pressure components derived from the intrinsic lower oesophageal sphincter and the extrinsic compression of the oesophagus within the hiatal canal.

Introduction Laparoscopic fundoplication provides effective reflux control in patients with gastro-oesophageal reflux disease (GERD); however a proportion of patients that undergo surgery experience troublesome symptoms. Improved results may be possible if more was known about the structural factors that effect treatment outcome. This study applied concurrent MRI and HRM technology to compare the structure and function of the GEJ in GERD patients after fundoplication to control groups of GERD patients and healthy participants (HPs). Methods Eight GERD patients were studied at least 3 months after laparoscopic fundoplication with subjectively good treatment outcome (7M, age 18–67 years). Results of pH-impedance monitoring off acid suppression before and after fundoplication were available. 12 patients with GERD on medical therapy (7M, age 20–55 years) and 12 HPs (7M, age 26–36 years) with no history of gastro-intestinal disease or surgery. Validated MRI measurements of the oesophago-gastric insertion angle (Radiology in press) and gastric volumes were performed at baseline and after ingestion of high calorie meal (McDonalds Cheeseburger, Chips, Milkshake, 735 kcal). Visual Analogue Scales (100 mm VAS) documented dyspeptic symptoms. Results GEJ pressure increased from before to after fundoplication (8.3±1.2 vs 14.2±1.7 mm Hg, p=0.03) whereas acid exposure (10.3±2.2 vs 5.4±2.1, p=0.001) and reflux episodes reduced (39±3 vs 24±2, p=0.019). The insertion angle after the meal was more obtuse after surgery than in the disease and healthy controls (61° vs 48° vs 41°, p Conclusion Novel, quantitative MRI measurements demonstrate alterations to GEJ structure after fundoplication, specifically to the oesophago-gastric insertion angle, that are linked to gastric retention of air and the sensation of bloating, even in patients with a good subjective outcome. Modification of surgical technique to restore more normal GEJ morphology may be equally effective for reflux protection but cause less troublesome bloating.