Relaxation of the lower-oesophageal sphincter during swallowing.

A rapid-pull through technique was used to measure lower oesophageal sphincter pressure before and immediately after swallowing. Often no high pressure zone could be detected after a swallow although sometimes an attenuated pressure profile persisted, associated with weakly developed peristalsis. The persistence of normal sphincter profiles was associated with failure of peristalsis or weak peristaltic pressure waves. Overall, there was a significant drop in mean sphincter pressure after swallowing.