Three-dimensional imaging of the lower esophageal sphincter in healthy subjects and gastroesophageal reflux.

The resting pressure and intraabdominal length are the most important factors which determine competence of the lower esophageal sphincter (LES). The intraabdominal sphincter vector volume (ISVV) is a single value which takes into account both of these measurements. Normal values of ISVV and of the total sphincter vector volume (TSVV) were established in 20 normal subjects. The sensitivity and the specificity of ISVV and TSVV were then evaluated in 81 patients with gastroesophageal reflux disease (GERD) and in 19 normal subjects and were compared with the usual stepwise pullback manometry (SPM) measuring the resting pressure of the LES at the respiratory inversion point. The motorized pullthrough technique was used to perform the vector volume procedure. Normal values of ISVV were 1870-10740 mm Hg2 x mm, and of TSVV 2200-13110 mm Hg2 x mm. The sensitivity of ISVV was 93.8% (p < 0.05), of TSVV 80.2%, and of SPM 81.5%. The specificity of ISVV and TSVV was 89.5% and of SPM 78.9% (not significant). Analysis of the intraabdominal sphincter vector volume is more sensitive than the total sphincter vector volume or standard stationary manometry in establishing a defective LES in patients with GERD. Intraabdominal sphincter vector volume analysis will allow surgeons better to identify patients with a defective LES who may be suitable for antireflux surgery.