Left ventricular twist mechanics in a canine model of reversible congestive heart failure: a pilot study.
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.
Wang
Jianwen
J
Department of Cardiology, Methodist DeBakey Heart and Vascular Center, The Methodist Hospital Research Institute, Houston, TX 77030, USA.
Nagueh
Sherif F
SF
Mathuria
Nilesh S
NS
Shih
Hue-Teh
HT
Panescu
Dorin
D
Khoury
Dirar S
DS
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*