title: Left ventricular strain and strain rate: characterization of the effect of load in human subjects.
abstract: OBJECTIVE
  Left ventricular (LV) strain and strain rate have been proposed as novel indices of systolic function; however, there are limited data about the effect of acute changes on these parameters.
  
  
  RESULTS
  Simultaneous Millar micromanometer LV pressure and echocardiographic assessment were performed on 18 patients. Loading was altered sequentially by the administration of glyceryl trinitrate (GTN) and saline fluid loading. Echocardiographic speckle tracking imaging was used to quantify the peak systolic strain (S) and peak systolic strain rate (SR S) and dp/dt max was recorded from the micromanometer data. GTN administration decreased preload (LV end diastolic pressure [LVEDP]: 15.7 vs. 8.4 mmHg, P < 0.001) and afterload (end systolic wall stress: 74 vs. 43 x 10(3)dyn/cm(2), P < 0.001). Administration of fluid increased preload (LVEDP: 11.3 vs. 18.1 mmHg, P < 0.001) and increased wall stress (53 vs. 62 x 10(3)dyn/cm(2), P < 0.003). Administration of GTN resulted in increased circumferential SR S (-1.2 vs. -1.7s(-1), P < 0.01) and longitudinal SR S (-0.9 vs. -1.0 s(-1), P < 0.001). The administration of fluid resulted in decreased circumferential SR S (-1.5 vs. -1.3s(-1), P < 0.01) and longitudinal SR S (-1.0 vs. -0.9s(-1), P < 0.01). As preload and afterload increased, decrease in circumferential SR S (r = 0.63, P < 0.001; r = 0.56, P<0.001) and longitudinal SR S were observed (r = 0.42, P < 0.003; r = 0.49 P < 0.001).
  
  
  CONCLUSIONS
  Circumferential and longitudinal peak strain and systolic strain rate are sensitive to acute changes in load, an important factor that needs to be considered in their application as indices of systolic function.
authors.affiliation: Cardiac Investigation Unit, St Vincent's Hospital Melbourne, PO Box 2900, Fitzroy, Victoria, Australia. 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: Jan
authors.initials: J
authors.lastname: D'hooge
authors.forename: Andrew I
authors.initials: AI
authors.lastname: MacIsaac
authors.forename: David L
authors.initials: DL
authors.lastname: Prior
mesh_terms: D000368:Aged; D017023:Coronary Angiography / Q000379:methods; D015150:Echocardiography, Doppler / Q000379:methods; D025401:Echocardiography, Stress / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008365:Manometry / Q000379:methods; D008875:Middle Aged; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012965:Sodium Chloride / Q000008:administration & dosage; D013318:Stroke Volume / Q000502:physiology*; D013997:Time Factors; D016277:Ventricular Function, Left / Q000502:physiology*
chemical_list: D012965:Sodium Chloride