title: The relative value of strain and strain rate for defining intrinsic myocardial function.
abstract: It is well accepted that strain and strain rate deformation parameters are not only a measure of intrinsic myocardial contractility but are also influenced by changes in cardiac load and structure. To date, no information is available on the relative importance of these confounders. This study was designed to investigate how strain and strain rate, measured by Doppler echocardiography, relate to the individual factors that determine cardiac performance. Echocardiographic and conductance measurements were simultaneously performed in mice in which individual determinants of cardiac performance were mechanically and/or pharmacologically modulated. A multivariable analysis was performed with radial and circumferential strains and peak systolic radial and circumferential strain rates as dependent parameters and preload recruitable stroke work (PRSW), arterial elastance (E(a)), end-diastolic pressure, and left ventricular myocardial volume (LVMV) as independent factors representing myocardial contractility, afterload, preload, and myocardial volume, respectively. Radial strain was most influenced by E(a) (β = -0.58, R(2) = 0.34), whereas circumferential strain was strongly associated with E(a) and moderately with LVMV (β = 0.79 and -0.52, respectively, R(2) = 0.54). Radial strain rate was related to both PRSW and LVMV (β = 0.79 and -0.62, respectively, R(2) = 0.50), whereas circumferential strain rate showed a prominent correlation only with PRSW (β = -0.61, R(2) = 0.51). In conclusion, strain (both radial and circumferential) is not a good surrogate measure of intrinsic myocardial contractility unless the strong confounding influence of afterload is considered. Strain rate is a more robust measure of contractility that is less influenced by changes in cardiac load and structure. Thus, peak systolic strain rate is the more relevant parameter to assess myocardial contractile function noninvasively.
authors.affiliation: Cardiovascular Imaging and Dynamics, Department of Cardiovascular Diseases, Catholic University Leuven, Belgium. vesselina.ferferieva@uz.kuleuven.be
authors.forename: V
authors.initials: V
authors.lastname: Ferferieva
authors.forename: A
authors.initials: A
authors.lastname: Van den Bergh
authors.forename: P
authors.initials: P
authors.lastname: Claus
authors.forename: R
authors.initials: R
authors.lastname: Jasaityte
authors.forename: P
authors.initials: P
authors.lastname: Veulemans
authors.forename: M
authors.initials: M
authors.lastname: Pellens
authors.forename: A
authors.initials: A
authors.lastname: La Gerche
authors.forename: F
authors.initials: F
authors.lastname: Rademakers
authors.forename: P
authors.initials: P
authors.lastname: Herijgers
authors.forename: J
authors.initials: J
authors.lastname: D'hooge
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002316:Cardiotonic Agents / Q000494:pharmacology; D004195:Disease Models, Animal; D004280:Dobutamine / Q000494:pharmacology; D015150:Echocardiography, Doppler; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology; D017379:Hypertrophy, Left Ventricular / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009200:Myocardial Contraction / Q000187:drug effects; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000503:physiopathology*; D011237:Predictive Value of Tests; D013314:Stress, Mechanical; D013997:Time Factors; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000503:physiopathology*; D016277:Ventricular Function, Left / Q000187:drug effects; D017725:Ventricular Pressure
chemical_list: D002316:Cardiotonic Agents; D004280:Dobutamine