title: Esophagogastric Junction Morphology and Distal Esophageal Acid Exposure.
abstract: The Chicago classification has recently added a morphological subclassification for the esophagogastric junction (EGJ). Our aim was to assess the distal esophageal acid exposure in patients with this new Chicago EGJ-type IIIa and IIIb classification.
  
  
  
  From a prospectively collected high-resolution manometry (HRM) database, we identified patients who underwent 24-h pH study between October 2011 and June 2015 and were diagnosed with EGJ-type III based on HRM. Chicago EGJ-type III is defined as the inter-peak nadir pressure ≤gastric pressure and a lower esophageal sphincter (LES)-crural diaphragm (CD) separation >2 cm [IIIa-pressure inversion point (PIP) remains at CD level and IIIb-PIP remains at LES level]. We classified the patients into reflux group [DeMeester score >14.72 or Fraction time pH (<4) > 4.2 %] and non-reflux group based on 24-h pH study.
  
  
  
  Fifty patients were identified that satisfied the study criteria, of which 37 patients (74 %) were EGJ-type IIIa. In those with EGJ-type IIIb, abdominal LES length (AL) in reflux group was significantly shorter than the non-reflux group (0.8 vs. 1.8, p < 0.05). EGJ-type IIIa patients showed significantly higher value for DeMeester score and Fraction time pH and more often had a positive pH study than EGJ-type IIIb patients (DeMeester score: 26.7 vs. 11.7, p < 0.05; Fraction time pH: 7.9 vs. 2.6, p < 0.05; positive pH study: 81.1 vs. 30.8 %, p < 0.001). Reflux was more common in LES-CD ≥ 3 cm than that in LES-CD < 3 cm (85 vs. 56.7 %, p < 0.05).
  
  
  
  A subset of patients with >2-cm LES-CD separation (type IIIb) maintain a physiological intra-abdominal location of the EGJ and are less likely to have reflux. A LES-CD ≥ 3 cm seems to discern a hiatus hernia of clinical significance.
authors.affiliation: Department of Surgery, Creighton University School of Medicine, Creighton University Medical Center, Omaha, NE, 68131, USA.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Akimoto
authors.affiliation: Creighton University School of Medicine (Phoenix Campus), Phoenix, AZ, 85013, USA.
authors.forename: Saurabh
authors.initials: S
authors.lastname: Singhal
authors.affiliation: Creighton University School of Medicine (Phoenix Campus), Phoenix, AZ, 85013, USA.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Masuda
authors.affiliation: Department of Surgery, Creighton University School of Medicine, Creighton University Medical Center, Omaha, NE, 68131, USA.
authors.forename: Se Ryung
authors.initials: SR
authors.lastname: Yamamoto
authors.affiliation: Department of Surgery, Creighton University School of Medicine, Creighton University Medical Center, Omaha, NE, 68131, USA.
authors.forename: Wendy Jo
authors.initials: WJ
authors.lastname: Svetanoff
authors.affiliation: Department of Surgery, Creighton University School of Medicine, Creighton University Medical Center, Omaha, NE, 68131, USA. Sumeet.Mittal@DignityHealth.org.|Creighton University School of Medicine (Phoenix Campus), Phoenix, AZ, 85013, USA. Sumeet.Mittal@DignityHealth.org.|Norton Thoracic Institute, St Joesph's Hospital and Medical Center, Dignity Health, Phoenix, AZ, 85013, USA. Sumeet.Mittal@DignityHealth.org.
authors.forename: Sumeet K
authors.initials: SK
authors.lastname: Mittal
mesh_terms: D003964:Diaphragm / Q000473:pathology / Q000503:physiopathology*; D049630:Esophageal Sphincter, Lower / Q000473:pathology / Q000503:physiopathology*; D050782:Esophageal pH Monitoring; D004943:Esophagogastric Junction / Q000473:pathology / Q000503:physiopathology; D005260:Female; D005764:Gastroesophageal Reflux / Q000473:pathology / Q000503:physiopathology*; D006551:Hernia, Hiatal / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008365:Manometry; D008875:Middle Aged; D009929:Organ Size
keywords: Crural diaphragm; Gastroesophageal reflux disease; Hiatal hernia; High-resolution manometry; Lower esophageal sphincter; Pressure inversion point