title: Second trimester ultrasound: reference values for two-dimensional speckle tracking-derived longitudinal strain, strain rate and time to peak deformation of the fetal heart.
abstract: BACKGROUND
  Data on myocardial deformation during the internationally widely used second-trimester screening are scarce and confusing. Reference values of time to peak strain are missing. The aims of this study were to assess reference values derived from two-dimensional speckle-tracking echocardiography for global and regional longitudinal right ventricular (RV) and left ventricular (LV) strain, strain rate, and time to peak global strain and to determine the influence of heart rate and gender on these strain parameters.
  
  
  METHODS
  Seventy-five healthy fetuses were enrolled during second-trimester ultrasound (20-24 weeks). Clips with high frame rates (mean, 132 frames/sec) and two-dimensional (B-mode) grayscale images of apical or basal four-chamber views of both ventricles were used for offline analyses.
  
  
  RESULTS
  There were no statistically significant differences in global strain and strain rate between both ventricles (P = .679 and P = .734, respectively) or among the RV, septal, and LV free walls. Regional measurements, modeled also as an interaction of wall and segment (basal mid and apical), showed only a small, statistically significant difference between the basal RV and LV free walls. Strain and strain rate values were independent of heart rate. The mean time to peak LV global strain adjusted for heart rate was statistically significantly shorter than the RV value (P < .0001]). Strain, strain rate, and time to peak global strain were not found to be associated with gender.
  
  
  CONCLUSIONS
  The establishment of second-trimester two-dimensional speckle-tracking echocardiographic reference values for global and regional strain, strain rate, and time to peak global strain in a healthy fetal cohort is a mandatory prerequisite for its use in evaluating (pathologic) changes in both ventricular functions during pregnancy.
authors.affiliation: Children's Heart Centre, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. l.kapusta@cukz.umcn.nl
authors.forename: Livia
authors.initials: L
authors.lastname: Kapusta
authors.forename: Gur
authors.initials: G
authors.lastname: Mainzer
authors.forename: Zeev
authors.initials: Z
authors.lastname: Weiner
authors.forename: Lisa
authors.initials: L
authors.lastname: Deutsch
authors.forename: Asaad
authors.initials: A
authors.lastname: Khoury
authors.forename: Sami
authors.initials: S
authors.lastname: Haddad
authors.forename: Avraham
authors.initials: A
authors.lastname: Lorber
mesh_terms: D019245:Compressive Strength / Q000502:physiology; D004452:Echocardiography / Q000379:methods* / Q000592:standards*; D055119:Elastic Modulus / Q000502:physiology; D005260:Female; D005318:Fetal Heart / Q000000981:diagnostic imaging* / Q000196:embryology / Q000502:physiology*; D006801:Humans; D038622:Internationality; D008297:Male; D011247:Pregnancy; D011262:Pregnancy Trimester, Second / Q000502:physiology*; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013718:Tensile Strength / Q000502:physiology; D016216:Ultrasonography, Prenatal / Q000379:methods* / Q000592:standards*