Use of endoluminal ultrasound to evaluate gastrointestinal motility.

The use of high-frequency ultrasound transducers in the gastrointestinal tract (GI) has already yielded remarkable findings concerning the anatomy, physiology and pathophysiology of the GI tract and of various motility disorders. These transducers have made completely invisible portions of the GI tract (the longitudinal smooth muscle, muscles of the upper esophageal sphincter, components of the gastroesophageal junction high-pressure zone, and the muscle of the anal sphincter complex) accessible to investigation. Use of simultaneous ultrasound and manometry has allowed the exploration of the normal physiology of peristaltic contraction. The components of the high-pressure zone of the distal and proximal esophagus have been isolated and the movement of these components has been studied individually and as a group. Various esophageal motility disorders have been investigated including achalasia, scleroderma, Barrett's esophagus and diffuse esophageal spasm. The possible etiology of the symptoms of esophageal chest pain and heartburn (sustained esophageal contractions of the longitudinal smooth muscle), have been studied. The possible underlying pathophysiology of GERD (the missing gastric clasp and sling fiber pressure profile) has been explored. Three-dimensional high-frequency ultrasound imaging has allowed the peristaltic contraction sequence to be viewed in a completely new and unique manner. The biomechanics of both esophageal contraction and the gastroesophageal junction high-pressure zone have been investigated and the mechanical advantage of esophageal shorting has been studied. The mechanism of action of standard surgical and newer endoscopic therapies for GERD has been defined. Future applications of this technology are limited only by our imagination.