Three-dimensional manometric imaging of the lower esophageal sphincter.

The lower esophageal sphincter provides a pressure barrier between the negative intrathoracic and positive intra-abdominal pressure environment. The resistance of the lower esophageal sphincter to reflux of gastric juice is determined by the integrated effects of radial pressures exerted over the entire length of the sphincter. This can be best quantitated by manometry with radially oriented pressure transducers and calculation of the SPVV (ie, the volume of the 3D sphincter pressure image). Validation studies have shown that the SPVV is superior to standard parameters of sphincter strength (ie, sphincter resting pressure, overall length, and abdominal length) and improves the identification of patients that will benefit from an anti-reflux procedure. This is particularly so in patients with subtle sphincter defects and patients with increased esophageal acid exposure and no mucosal injury on endoscopy. In addition, asymmetry of the sphincter that may contribute to incompetence of the cardia can only be detected by 3D manometric sphincter imaging. The effect of an anti-reflux procedure in controlling reflux is dependent on restoration of the defective 3D sphincter pressure image. Failure to do so is associated with recurrent or persistent reflux. 3D sphincter imaging can also illustrate the severely asymmetric and hypertensive sphincter in patients with achalasia and the effect of myotomy with or without a concomitant anti-reflux procedure on the sphincter pressure profile.