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J Thorac Cardiovasc Surg 1997;114:968-974
© 1997 Mosby, Inc.

GENERAL THORACIC SURGERY

EFFECT OF ESOPHAGEAL DISTENTION ON PRESSURE AND ELECTROMYOGRAPHIC ACTIVITY OF THE PHARYNGOESOPHAGEAL SPHINCTER, WITH IDENTIFICATION OF THE ESOPHAGOPHARYNGEAL REFLEX

Received for publication Feb. 25, 1997 Revisions requested July 11, 1997 Revisions received July 23, 1997 Accepted for publication July 24, 1997 Address for reprints: Ahmed Shafik, MD, PhD, 2 Talaat Harb St., Cairo, Egypt.

Abstract

Purpose: My purpose was to study the effect of balloon-produced esophageal distention on the pharyngoesophageal sphincter to shed light on the mechanism by which esophagopharyngeal reflux is prevented. Method: Nine dogs (mean weight 15.7 ± 4.3 kg) were used for the study. A balloon-tipped catheter was introduced into the esophagus and a manometric catheter into the pharyngoesophageal sphincter. The pressure response of the pharyngoesophageal sphincter to esophageal distention was recorded. The response was also tested while the esophagus and the pharyngoesophageal sphincter were anesthetized, each separately. In six of nine dogs the electromyographic response of the pharyngoesophageal sphincter to esophageal distention was studied before and after the esophagus was anesthetized. Results: Lower and midesophageal distention produced no pressure changes in the pharyngoesophageal sphincter (p = 0.082). Upper esophageal distention effected an elevation in pharyngoesophageal sphincter pressure (p = 0.024), which showed no further rise when the distending volume was increased. The anesthetized pharyngoesophageal sphincter did not respond to esophageal distention. Likewise, the pharyngoesophageal sphincter did not respond to distention of the anesthetized upper esophagus. Esophageal distention produced increased electromyographic activity of the pharyngoesophageal sphincter, but no activity was recorded in response to distention of the anesthetized esophagus. Conclusion: This study has demonstrated contraction of the pharyngoesophageal sphincter on distention of the upper esophagus. This response seems to prevent esophagopharyngeal reflux and choking and is postulated to be evoked by means of an "esophagopharyngeal reflex."