title: Transient lower esophageal sphincter relaxations do not result from passive opening of the cardia by gastric distention.
abstract: OBJECTIVE
  Transient lower esophageal sphincter relaxation is the main mechanism for gastroesophageal reflux. Although there is evidence that transient lower esophageal sphincter relaxations are neurally mediated, another school of thought is that transient lower esophageal sphincter relaxations result from gastric distention, which shortens the sphincter to the point where it opens and the pressure decreases. We assessed the relationship of transient lower esophageal sphincter relaxation to gastroesophageal junction opening in an unsedated human model.
  
  
  METHODS
  Seven healthy volunteers (6 men and 1 woman, aged 18-53 years) were studied while they were sitting. Manometry was performed by using a sleeve catheter passed through 1 nostril. A 5.3-mm endoscope was placed through the other nostril to obtain a retroflexed view of the cardia. The biopsy channel was connected to a barostat to distend the stomach with air at 15 mm Hg for 30 minutes. Manometric and endoscopic video-recording times were synchronized but scored independently.
  
  
  RESULTS
  The transient lower esophageal sphincter relaxation onset invariably preceded gastroesophageal junction opening (median, 5.0 seconds; range, 0.5-20.7 seconds; P < .001). The transient lower esophageal sphincter relaxation nadir also typically occurred before gastroesophageal junction opening (median, 2.1 seconds; range, -4.2 to +19.5 seconds; P < .001). Once open, the gastroesophageal junction moved proximally for the duration of the transient lower esophageal sphincter relaxation. Termination of transient lower esophageal sphincter relaxations occurred about the time the time of gastroesophageal junction closure.
  
  
  CONCLUSIONS
  These data refute the hypothesis that transient lower esophageal sphincter relaxations result from passive mechanical distraction of the gastroesophageal junction. Rather, transient lower esophageal sphincter relaxations must occur before the gastroesophageal junction can open.
authors.affiliation: Division of Gastroenterology & Hepatology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA. bmassey@mcw.edu
authors.forename: Benson T
authors.initials: BT
authors.lastname: Massey
authors.forename: Chelsey
authors.initials: C
authors.lastname: Simuncak
authors.forename: Nicole J
authors.initials: NJ
authors.lastname: LeCapitaine-Dana
authors.forename: Sudhindra
authors.initials: S
authors.lastname: Pudur
mesh_terms: D000293:Adolescent; D000328:Adult; D002299:Cardia / Q000033:anatomy & histology / Q000502:physiology*; D016099:Endoscopy, Gastrointestinal; D049630:Esophageal Sphincter, Lower / Q000502:physiology*; D005260:Female; D005764:Gastroesophageal Reflux / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008365:Manometry; D008875:Middle Aged; D011312:Pressure; D014741:Video Recording