title: Sensation evoked by esophageal distension in functional chest pain patients depends on mechanical stress rather than on ischemia.
abstract: BACKGROUND
  Functional chest pain is commonly reproduced by bag distension in the esophageal body. It is unknown whether such pain is primarily associated with mechanical stress and strain (force-deformation) or with changes in mucosal perfusion.
  
  
  METHODS
  Fourteen patients (6M, 8F, average age 55.9 years) underwent ramp bag distension before and after injection of 20 mg butylscopolamine bromide (BS) using a novel bag catheter incorporating endosonography and laser Doppler perfusion monitoring. Healthy subjects served as controls. Mucosal perfusion was evaluated and stress and strain were computed and related to the sensation.
  
  
  RESULTS
  The symptom score increased with bag volume (P < 0.001). Volume as a function of pressure was higher in patients than in controls (P < 0.001), both before and during BS. The stress-strain relationship was exponential and indicated a stiffer esophageal wall in patients especially before BS (P < 0.01). The stress-strain curves indicate increased muscle tone in the functional chest pain patients. The perfusion decreased with increasing symptom score from visual analog scale 1-7 during BS. The decrease was on average 18.9% in patients and 19.7% in controls (P = ns). Multiple regression analysis from distensions during BS showed that the discomfort/pain sensations depended on stress and strain (P < 0.001) and with stress as the largest contributor. Perfusion did not contribute.
  
  
  CONCLUSIONS
  Pain evoked by bag distension in patients with functional chest pain is stress-dependent rather than dependent on mucosal perfusion. Furthermore, the esophagus of the patients was characterized by more pronounced muscle tone during the distensions.
authors.affiliation: Institute of Medicine, University of Bergen, Bergen, Norway. sodahoff@mimer.no
authors.forename: D A L
authors.initials: DA
authors.lastname: Hoff
authors.forename: H
authors.initials: H
authors.lastname: Gregersen
authors.forename: S
authors.initials: S
authors.lastname: Ødegaard
authors.forename: B T
authors.initials: BT
authors.lastname: Hjertaker
authors.forename: J G
authors.initials: JG
authors.lastname: Hatlebakk
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002404:Catheterization; D002637:Chest Pain / Q000503:physiopathology*; D003627:Data Interpretation, Statistical; D004947:Esophagus / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000502:physiology*; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007511:Ischemia / Q000503:physiopathology*; D017078:Laser-Doppler Flowmetry; D008297:Male; D008365:Manometry; D008875:Middle Aged; D009092:Mucous Membrane / Q000098:blood supply; D010147:Pain Measurement; D010812:Physical Stimulation; D012039:Regional Blood Flow / Q000502:physiology; D013314:Stress, Mechanical; D014463:Ultrasonography; D055815:Young Adult