title: Mechanical characteristics of distension-evoked peristaltic contractions in the esophagus of systemic sclerosis patients.
abstract: BACKGROUND
  Systemic sclerosis (SS) patients with severe esophageal affection have impaired peristalsis. However, motor function evaluated in vivo by manometry and fluoroscopy does not provide detailed information about the individual contraction cycles.
  
  
  OBJECTIVE
  To apply, for the first time in gastrointestinal (GI) patients, a method and principles modified from cardiac research to study esophageal muscle behavior in SS patients.
  
  
  METHODS
  Muscle contraction cycles were analyzed using pressure-cross-sectional area (P-CSA) loops during distension pressure up to 5 kPa. The probe with bag and electrodes for CSA measurements was positioned 7 and 15 cm above the lower esophageal sphincter (LES) in eleven healthy volunteers and eleven SS patients. The P-CSA, the wall tension, Δtension (afterload tension - preload tension), contraction velocity, work output (area of the tension-CSA loops), and power output (preload tension × CSA rate) were analyzed.
  
  
  RESULTS
  The P-CSA loops consisted of phases with relaxation and contraction behavior. The tension-stretch ratio loops in patients were shifted to the left at both distension sites, indicative of a stiffer wall in patients. Lower contraction amplitudes and smaller P-CSA loops were observed for the SS patients. The work output, power output, Δtension, and contraction velocity were lower in patients (P < 0.001). Association was found between disease duration and the work output, Δtension, and velocity at pressure steps higher than 3 kPa (P < 0.05).
  
  
  CONCLUSIONS
  Distension-evoked esophageal contraction can be studied in vivo and analyzed with advanced methods. Increased esophageal stiffness and impaired muscle function that depended on disease duration were observed for SS patients. The analysis may be useful for characterization of other diseases affecting GI function.
authors.affiliation: Mech-Sense, Aalborg Hospital Science and Innovation Centre, Aarhus University Hospital, Sdr. Skovvej 15, 9000 Aalborg, Denmark. hg@rn.dk
authors.forename: Hans
authors.initials: H
authors.lastname: Gregersen
authors.forename: Gerda E
authors.initials: GE
authors.lastname: Villadsen
authors.forename: Donghua
authors.initials: D
authors.lastname: Liao
mesh_terms: D000328:Adult; D000368:Aged; D004106:Dilatation / Q000379:methods*; D015154:Esophageal Motility Disorders / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D004947:Esophagus / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008365:Manometry; D008875:Middle Aged; D010528:Peristalsis / Q000502:physiology*; D011312:Pressure; D011379:Prognosis; D012595:Scleroderma, Systemic / Q000150:complications / Q000503:physiopathology*; D012720:Severity of Illness Index