title: Left ventricular twist mechanics in a canine model of reversible congestive heart failure: a pilot study.
abstract: BACKGROUND
  Left ventricular (LV) twist dynamics play an important role in LV systolic and diastolic function. The aim of this preliminary study was to investigate LV twist dynamics in a canine model of reversible congestive heart failure (CHF).
  
  
  METHODS
  Pacing systems were implanted in adult dogs, and continuous chronic right ventricular pacing (230-250 beats/min) was applied until CHF induction. Pacing was then stopped to allow the heart to recover. Echocardiography and LV catheterization were performed at baseline, during CHF while pacing was temporarily switched off, and during recovery. LV twist was computed as the difference between apical and basal rotation measured using 2-dimensional speckle tracking. Torsion was further calculated as LV twist divided by the LV long axis. The untwisting rate was computed as the peak diastolic time derivative of twist.
  
  
  RESULTS
  In 6 dogs that completed the study, we found that CHF developed after 2 to 4 weeks of pacing, with LV end-diastolic volume, end-systolic volume, end-diastolic pressure, and the time constant of relaxation during isovolumic relaxation period (tau) all increasing significantly compared with baseline and recovering to normal levels 2 to 4 weeks after pacing was stopped. LV twist, torsion, and untwisting rate decreased significantly with CHF compared with baseline and improved during recovery from CHF.
  
  
  CONCLUSIONS
  LV twist dynamics reflect pacing-induced CHF and its reversal as assessed by echocardiographic speckle tracking.
authors.affiliation: Department of Cardiology, Methodist DeBakey Heart and Vascular Center, The Methodist Hospital Research Institute, Houston, TX 77030, USA.
authors.forename: Jianwen
authors.initials: J
authors.lastname: Wang
authors.forename: Sherif F
authors.initials: SF
authors.lastname: Nagueh
authors.forename: Nilesh S
authors.initials: NS
authors.lastname: Mathuria
authors.forename: Hue-Teh
authors.initials: HT
authors.lastname: Shih
authors.forename: Dorin
authors.initials: D
authors.lastname: Panescu
authors.forename: Dirar S
authors.initials: DS
authors.lastname: Khoury
mesh_terms: D000818:Animals; D004285:Dogs; D006333:Heart Failure / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008297:Male; D009200:Myocardial Contraction; D010865:Pilot Projects; D012399:Rotation; D054159:Torsion, Mechanical; D014463:Ultrasonography; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000503:physiopathology*