title: Strain, strain rate, and the force frequency relationship in patients with and without heart failure.
abstract: BACKGROUND
  The aim of this study was to examine the effect of heart rate (HR) on indices of deformation in adults with and without heart failure (HF) who underwent simultaneous high-fidelity catheterization of the left ventricle to describe the force-frequency relationship.
  
  
  METHODS
  Right atrial pacing to control HR and high-fidelity recordings of left ventricular (LV) pressure were used to inscribe the force-frequency relationship. Simultaneous two-dimensional echocardiographic imaging was acquired for speckle-tracking analysis.
  
  
  RESULTS
  Thirteen patients with normal LV function and 12 with systolic HF (LV ejection fraction, 31 ± 13%) were studied. Patients with HF had depressed isovolumic contractility and impaired longitudinal strain and strain rate. HR-dependent increases in LV+dP/dt(max), the force-frequency relationship, was demonstrated in both groups (normal LV function, baseline to 100 beats/min: 1,335 ± 296 to 1,564 ± 320 mm Hg/sec, P < .0001; HF, baseline to 100 beats/min: 970 ± 207 to 1,083 ± 233 mm Hg/sec, P < .01). Longitudinal strain decreased significantly (normal LV function, baseline to 100 beats/min: 18.0 ± 3.5% to 10.8 ± 6.0%, P < .001; HF: 9.4 ± 4.1% to 7.5 ± 3.4%, P < .01). The decrease in longitudinal strain was related to a decrease in LV end-diastolic dimensions. Strain rate did not change with right atrial pacing.
  
  
  CONCLUSIONS
  Despite the inotropic effect of increasing HR, longitudinal strain decreases in parallel with stroke volume as load-dependent indices of ejection. Strain rate did not reflect the modest HR-related changes in contractility; on the other hand, the use of strain rate for quantitative stress imaging is also less likely to be confounded by chronotropic responses.
authors.affiliation: The Mecklinger and Posluns Cardiac Catheterization Research Laboratory, Division of Cardiology, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada. smak@mtsinai.on.ca
authors.forename: Susanna
authors.initials: S
authors.lastname: Mak
authors.forename: Harriette G C
authors.initials: HG
authors.lastname: Van Spall
authors.forename: Rodrigo V
authors.initials: RV
authors.lastname: Wainstein
authors.forename: Zion
authors.initials: Z
authors.lastname: Sasson
mesh_terms: D016022:Case-Control Studies; D016009:Chi-Square Distribution; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000473:pathology*; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology*; D013223:Statistics as Topic; D013318:Stroke Volume; D014463:Ultrasonography; D016277:Ventricular Function, Left