Marked asymmetry of LES: important element of LES barrier in subsets of patients with reflux symptoms.

Computerized axial manometry (CAM) of the lower esophagus measures squeeze pressure at multiple points in each segment of the lower esophageal sphincter (LES), calculates several unique parameters of LES function, and constructs a 3-D display of the LES. Whether parameters derived from CAM, such as the radial mean pressure (LESrmp), Asymmetry (Asym), and Vector Volume (VV), have relevance to function of the LES remains undefined. This study compares the results of CAM in patients with gastroesophageal reflux disease (GERD) and controls. There were 54 patients with GERD and 21 volunteers; all underwent CAM as part of their evaluation; GERD was defined by clinical and endoscopic examinations, and all patients had abnormal 24-hour pH tests. Statistical evaluation was performed. The LESrmp and the Vector Volume were significantly correlated in both groups of patients and differed significantly in both. Asymmetry of the LES was a significant negative factor in LES strength as shown by VV and LESrmp. Asymmetry alone, however, did not show a strong correlation with reflux. Asymmetry is indirectly correlated with the major determinants of LES strength; in patients with low VV, asymmetry might be a critical factor. When a high VV is present, asymmetry has no particular relevance. CAM provides invaluable measurements of the LES.