Resistance and Reflex Function of the Lower Esophageal Sphincter

¹ From the Evans Memorial, Massachusetts Memorial Hospitals and the Department of Medicine, Boston University School of Medicine, Boston, Massachusetts

A zone of high pressure, 3 cm long, has been demonstrated in the distal esophagus by intraluminal manometry. To evaluate the sphincteric function of this zone, radiopaque liquid was layered into the esophagus of each of 10 subjects in an upright position so that a hydrostatic force was exerted. The sphincteric zone, with the diaphragm relaxed, offered greater resistance to this hydrostatic force than could be attributed to the inverse gastroesophageal pressure gradient. Reflex relaxation of the zone in response to a simple stimulus, i.e. balloon esophageal distention, was demonstrated in six additional subjects. These properties are evidence for a physiologically active lower esophageal sphincter.