Acid-induced esophageal shortening in humans: A cause of hiatus hernia?

BACKGROUND: Hiatus hernia and gastroesophageal reflux disease commonly coexist, and there is pathophysiological evidence that the presence of a hiatus hernia contributes to abnormal acid reflux. However, the cause of hiatus hernia remains unclear. In an animal model, it has been shown that acute acid injury to the esophagus results in esophageal shortening, raising the possibility that reflux esophagitis per se can contribute to the formation of hiatus hernia by inducing esophageal shortening. AIM: To determine whether luminal acid produces esophageal shortening in humans. METHODS: Twelve volunteers were each studied on two occasions, one week apart, in a double-blind, crossover trial. The location of the lower esophageal sphincter (LES), as well as the LES resting pressure and axial length were determined at baseline and then again after 20 min of either acid or saline perfusion. RESULTS: Acid perfusion did not induce significant changes in resting LES pressure but resulted in proximal migration of the LES (ie, esophageal shortening) by an average of 0.5 cm, with the largest proximal migration being 1.8 cm. In contrast, saline perfusion resulted in slight distal migration of the LES (ie, esophageal lengthening). CONCLUSIONS: Intraruminal acid perfusion causes longitudinal axis shortening of the esophagus and suggests that gastroesophageal acid reflux may contribute to the cause of hiatus hernia.