title: Left ventricular torsion parameters are affected by acute changes in load.
abstract: BACKGROUND
  Quantification of left ventricular torsion may provide new indices of systolic and diastolic function. We sought to characterize the effect of acute manipulation of load on cardiac torsion, plecotropy in human subjects.
  
  
  METHODS
  Simultaneous Millar LV pressure, micromanometry, and echocardiograms were performed on 18 patients (10 male, mean age 66 years) with normal systolic function. Loading was altered sequentially by the administration of glyceryl trinitrate (GTN) and saline fluid loading. Echocardiographic speckle tracking imaging was used to quantify LV torsion and event timing was recorded relative to mitral valve opening (MVO).
  
  
  RESULTS
  GTN administration decreased preload (LV end diastolic pressure: 15.7 vs 8.4 mmHg, P < 0.001), and afterload (wall stress: 140 vs 84 x10(3)dyn/cm(2), P < 0.02). Administration of fluid increased preload (LVEDP 11.3 vs 18.1 mmHg, P < 0.001) and increased wall stress, but to a lesser extent (102 vs 117 x10(3)dyn/cm(2), P < 0.003). GTN administration augmented peak torsion (8.4 vs 11.0 deg, P < 0.05), increased systolic torsion velocity (46.6 vs 65.3deg/sec, P < 0.01) and resulted in earlier onset of untwisting (-105 vs -127ms, P < 0.05). Fluid loading decreased the proportion of untwisting prior to MVO (39.0 vs 31.0%, P < 0.05), untwisting acceleration (-750 vs -592deg/sec/sec, P < 0.05) and delayed the timing of peak untwisting (-37.0 vs 9.1ms, P < 0.01), but did not affect systolic torsion parameters.
  
  
  CONCLUSIONS
  Left ventricular torsion parameters are sensitive to acute changes in load and therefore need to be interpreted in the context of current loading conditions.
authors.affiliation: Cardiac Investigation Unit, St. Vincent's Hospital Melbourne, Victoria, Australia 3065. andrew.burns@svhm.org.au
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Burns
authors.forename: Andre
authors.initials: A
authors.lastname: La Gerche
authors.forename: David L
authors.initials: DL
authors.lastname: Prior
authors.forename: Andrew I
authors.initials: AI
authors.lastname: Macisaac
mesh_terms: D000368:Aged; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D014102:Torsion Abnormality / Q000000981:diagnostic imaging*; D014463:Ultrasonography; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging*