Role of the lower esophageal sphincter and hiatal hernia in the pathogenesis of gastroesophageal reflux disease

The relative importance of the lower esophageal sphincter (LES) and hiatal hernia in the pathogenesis of gastroesophageal reflux disease is controvers ial. To identify the role of hiatal hernia and LES in reflux disease, 375 c onsecutive patients with foregut symptoms and no previous foregut surgery w ere evaluated. All patients underwent upper endoscopy stationary manometry, and 24-hour esophageal pH monitoring. Hiatal hernia was diagnosed endoscop ically, when the distance between the crural impression and the gastroesoph ageal junction was greater than or equal to 2 cm. The LES was considered st ructurally defective when the resting pressure was less than or equal to 6 mm Hg, the overall length was less than 2 cm, and/or the abdominal length w as less than 1 cm. Factors predicting abnormal esophageal acid exposure (co mposite score > 14.7) were analyzed using multivariate analysis. The presen ce of a hiatal hernia and a defective LES were identified as independent pr edictors of abnormal esophageal acid exposure. LES pressure and abdominal l ength were reduced in patients with hiatal hernia by 4 mm Hg and 0.4 cm, ir respective of the presence of gastroesophageal reflux disease. It is conclu ded that both a structurally defective LES and hiatal hernia are important factors in the pathogenesis of reflux disease. It is hypothesized that in t he presence of a structurally normal LES, the altered geometry of the cardi a imposed by a hiatal hernia facilitates the ability of gastric wall tensio n to pull open the sphincter.