MANOMETRIC VECTOR VOLUME ANALYSIS TO ASSESS LOWER ESOPHAGEAL SPHINCTER FUNCTION

The resistance provided by the manometric high pressure zone at the ga stroesophageal 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 a t the gastric notch and the semicircular 'clasps' at the lesser curvat ure side of the gastroesophageal junction. Pull-back manometry with ra dially oriented pressure transducers allows to assess these distinct c omponents of the human lower esophageal sphincter. With the recent int roduction of personal computers into the manometry laboratory, three-d imensional manometric images of the lower esophageal sphincter can be easily constructed, based on radially oriented pressures. The applicat ion of this new technology has shown that calculation of the sphincter pressure vector volume, i.e the volume circumscribed by the three-dim ensional manometric sphincter image, is superior to standard manometri c techniques in the assessment of lower esophageal sphincter function. The sphincter pressure vector volume is a particularly helpful parame ter to identify patients with gastroesophageal reflux disease who will not benefit from medical therapy and should consequently undergo earl y antireflux surgery. Vector volume analysis is also helpful in assess ing the cause of recurrent symptoms in patients with previous antirefl ux surgery. In patients with achalasia three-dimensional sphincter ima ging and vector volume analysis can illustrate a severely asymmetric a nd hypertensive sphincter and show the effect of myotomy with or witho ut a concomitant antireflux procedure on the sphincter pressure profil e.