Calculation of esophagogastric junction vector volume using three-dimensional high-resolution manometry

Lower esophageal sphincter vector volume (V-V) was developed in the late 1980s by Bombeck, as a quantification of sphincter integrity used to select reflux patients with a defective valve who may benefit from surgery. Its calculation required motorized pull-through of an 8-lumen water perfused manometry catheter with subsequent computerized reconstruction of sphincter morphology. Recently, a three-dimensional high-resolution manometry (3D-HRM) assembly (Given Imaging, Duluth, GA, USA) has been developed with the potential to assess real-time V-V. The aim of this study was to assess the feasibility of the calculation of V-V using the 3D-HRM assembly and to compare measures of its value using real-time 3D-HRM to simulated analogous measures. Eight asymptomatic controls (4F, ages 26-49) were studied in a supine position with a solid-state 3D-HRM assembly positioned across the esophagogastric junction (EGJ). The 9-cm 3D segment comprised 12 rings of 8 radially dispersed pressure sensors, each 2.5mm long and spaced 7.5mm apart on center. Recordings were done during normal respiration: (i) with the 3D-HRM segment in a stationary position across the EGJ; and (ii) during a station pull-through of the 3D-HRM segment withdrawing it across the EGJ at 5-mm increments with each position held for 30 seconds. EGJ cross-sectional vector areas (CSVAs) were computed using the irregular polygon area formula: C S V A = ( sin ( 360 n ) 2 ) × ( P 1 × P 2 + P 2 × P 3 ... P n × P 1 ) , and n = 8 radial sensors. V-V was computed as the sum of CSVAs at inspiration and end-expiration by three methods: real-time 3D-HRM, three-station composite, and single-sensor ring measurements. There were no statistic differences among the methods, and all methods showed significant differences between inspiration and expiration. Calculation of real-time V-V is feasible using the 3D-HRM. Moreover, the results of this study highlighted the potential primary role of the diaphragmatic hiatus in the pathophysiology of gastroesophageal reflux disease and the underrecognized but crucial role of the crural repair during the antireflux surgery.