The lower esophageal sphincter.

The lower esophageal sphincters (LES) together with the crural diaphragm are the major antireflux barriers protecting the esophagus from reflux of gastric content. However, reflux of gastric contents into the esophagus is a normal phenomenon in healthy individuals occurring primarily during episodes of transient lower esophageal sphincter relaxation (TLESR), defined as LES relaxation in the absence of a swallow. Transient lower esophageal sphincter relaxation is also the dominant mechanism of pathologic reflux in gastroesophageal reflux disorder (GERD) patients. Frequency of TLESR does not differ significantly between healthy individuals and those with GERD, but TLESRs are more likely to be associated with acid reflux in GERD patients. Understanding the mechanisms responsible for elicitation of a TLESR, using recently introduced novel technology is an area of intense interest. Pharmacologic and non-pharmacologic manipulation of receptors involved in the control of TLESR has recently emerged as a potential target for GERD therapy.