Mechanisms affecting lower oesophageal sphincter opening and oesophageal retention. A combined X-ray and manometry study.

Using simultaneous manometry and cineradiography, oesophageal evacuation was studied while contrast medium was infused via a catheter. The distal half of the oesophagus could be filled with contrast medium without triggering peristalsis. The hydrostatic pressure necessary to open the lower oesophageal sphincter (LES) was of approximately the same magnitude as the pressure gradient between oesophagus and LES. No significant relaxation of the LES could be observed at the initiation of swallowing. The LES may be looked upon not only as a sphincter preventing reflux but also as a gate which must be forced open by food.