[Stretch sphincter of the esophagus : Paradoxical sphincter with angiomyoelastic architecture]

The investigations described in this article clearly show that the lower esophageal sphincter (LES) represents a variation of circular muscular occlusive mechanisms found elsewhere in the gastrointestinal tract. The LES is a double layer stretch sphincter that operates in an apparently paradoxical manner: it closes when under stretch but opens when the muscle fibers contract. Impedance manometry studies demonstrate that the entire esophagus is involved in the normal functioning of the esophagus as well as in esophageal disorders. The pronounced elasticity of esophageal tissue is a functional feature that has its basis in the singular architecture of elastic fibers located between the muscle layers. All traditional forms of operative treatment of gastroesophageal reflux disease (GERD) impede the natural functioning of the stretch sphincter to a greater or lesser degree by locking it up. The cause of GERD is mainly by contraction of the esophagus brought about by the cephalad transposition of the stretch sphincter segment into the chest. In a sense this is an incipient axial hernia that frequently remains undiagnosed in the early stages. The operative repositioning of the stretch sphincter segment into the abdominal cavity provides sufficient restoration of the natural topographic relationships to achieve a cure of GERD. Whether this straightforward repair restores the function of the entire esophagus remains to be elucidated. The concept of the stretch provides a good explanation of the pathophysiology of achalasia, a condition in which a paralyzed paradoxical ring sphincter remains occluded. Successful myotomy approaches only split the muscularis propria layer of the stretch sphincter while leaving subepithelial muscle fibers intact that remain paralyzed. This limited intervention provides a good relief of symptoms.