Manometric vector volume analysis to assess lower esophageal sphincter function.

The resistance provided by the manometric high pressure zone at the gastroesophageal junction, is the major barrier against gastroesophageal reflux in man. Recent studies have shown that this high pressure zone has its correlate in the architecture of the gastric 'sling' fibres at the gastric notch and the semicircular 'clasps' at the lesser curvature side of the gastroesophageal junction. Pull-back manometry with radially oriented pressure transducers allows to assess these distinct components of the human lower esophageal sphincter. With the recent introduction of personal computers into the manometry laboratory, three-dimensional manometric images of the lower esophageal sphincter can be easily constructed, based on radially oriented pressures. The application of this new technology has shown that calculation of the sphincter pressure vector volume, i.e. the volume circumscribed by the three-dimensional manometric sphincter image, is superior to standard manometric techniques in the assessment of lower esophageal sphincter function. The sphincter pressure vector volume is a particularly helpful parameter to identify patients with gastroesophageal reflux disease who will not benefit from medical therapy and should consequently undergo early antireflux surgery. Vector volume analysis is also helpful in assessing the cause of recurrent symptoms in patients with previous antireflux surgery. In patients with achalasia three-dimensional sphincter imaging and vector volume analysis can illustrate a severely asymmetric and hypertensive sphincter and show the effect of myotomy with or without a concomitant antireflux procedure on the sphincter pressure profile.