title: Apical rotation by speckle tracking echocardiography: a simplified bedside index of left ventricular twist.
abstract: OBJECTIVE
  The study objective was to determine whether left ventricular (LV) apical rotation by speckle tracking echocardiography (STE) may serve as a clinically feasible index of LV twist. LV twist has been proposed as a sensitive marker of LV function, but clinical implementation has not been feasible because of the complexity and limitations of present methodologies.
  
  
  METHODS
  The relationship between apical rotation and LV twist was investigated in anesthetized dogs (n = 9) and a clinical study that included healthy controls (n = 18) and patients (n = 27) with previous myocardial infarction. Rotation by STE was compared with twist measured by magnetic resonance imaging and sonomicrometry in humans and dogs, respectively.
  
  
  RESULTS
  In dogs, apical rotation by STE correlated well with LV twist over a wide range of loading conditions and inotropic states, and during myocardial ischemia (R = 0.94, P < .01). Similarly, in humans there was a strong correlation between apical rotation and twist (R = 0.88, P < .01) but only a weak correlation between basal rotation and twist (R = 0.53, P < .01). Apical rotation accounted for 72% +/- 14% and 73% +/- 15% of the twisting deformation by magnetic resonance imaging in controls and patients, respectively. In dogs, apical rotation and twist decreased during myocardial ischemia (P < .05). In patients, LV twist and apical rotation were reduced (P < .05) only when LV ejection fraction was less than 50%.
  
  
  CONCLUSIONS
  Apical rotation represents the dominant contribution to LV twist, and apical rotation by STE reflects LV twist over a wide range of hemodynamic conditions. These findings suggest that apical rotation by STE may serve as a simple and feasible clinical index of LV twist.
authors.affiliation: Institute for Surgical Research, Rikshospitalet University Hospital, University of Oslo, Oslo, Norway.
authors.forename: Anders
authors.initials: A
authors.lastname: Opdahl
authors.forename: Thomas
authors.initials: T
authors.lastname: Helle-Valle
authors.forename: Espen W
authors.initials: EW
authors.lastname: Remme
authors.forename: Trond
authors.initials: T
authors.lastname: Vartdal
authors.forename: Eirik
authors.initials: E
authors.lastname: Pettersen
authors.forename: Ketil
authors.initials: K
authors.lastname: Lunde
authors.forename: Thor
authors.initials: T
authors.lastname: Edvardsen
authors.forename: Otto A
authors.initials: OA
authors.lastname: Smiseth