The Lower Esophageal Intrinsic Sphincter and the Mechanism of Reflux

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Abstract
Experimental observation in 82 dogs reaffirms the presence of a functional intrinsic lower esophageal sphincter and establishes this as the primary mechanism for the prevention of esophageal reflux and its attendant acid-peptic esophagitis. This sphincter can function in the intrathoracic position. It also functions in the absence of the diaphragmatic pinchcock mechanism or the acute angle of entry into the stomach. In the absence of a functional intrinsic sphincter, these other factors alone or in combination are incapable of preventing reflux. The normal intrinsic lower esophageal sphincter in the dog is unable to function properly when interference with its action is produced by distraction from abnormal traction or abnormal insertion of the phrenoesophageal membrane into the esophagus or both. This situation may occur in some humans and may explain in some instances why reflux is an inconstant finding with esophageal sliding hiatal hernias.