title: Normal ranges of left ventricular strain in children: a meta-analysis.
abstract: OBJECTIVE
  The definition of normal values of two-dimensional speckle-tracking echocardiography derived left ventricular (LV) deformation parameters, is of critical importance for the routine application of this modality in children. The objectives of this study were to perform a meta-analysis of normal ranges for longitudinal, circumferential and radial strain/strain rate values and to identify confounders that may contribute to differences in reported measures.
  
  
  RESULTS
  A systematic search was conducted. Studies describing normal healthy subjects and observational studies that used control groups as a comparison were included. Data were combined using a random-effect model. Effects of demographic, clinical and equipment variables were assessed through meta-regression. The search identified 1,192 subjects form 28 articles. Longitudinal strain (LS) normal mean values varied from -12.9 to -26.5 (mean, -20.5; 95% CI, -20.0 to -21.0). Normal mean values of circumferential strain (CS) varied from -10.5 to -27.0 (mean, -22.06; 95% CI, -21.5 to -22.5). Radial strain (RS) normal mean values varied from 24.9 to 62.1 (mean, 45.4; 95% CI, 43.0 to 47.8). Meta-regression showed LV end diastolic diameter as a significant determinant of variation for LS. Longitudinal systolic strain rate (LSRs) was significantly determined by the age and RS by the type of vendor used.
  
  
  CONCLUSIONS
  Variations among different normal ranges were dependent on the vendor used, LV end-diastolic diameter and age. Vendor-independent software for analyzing myocardial deformation in children, using images from different vendors would be the ideal solution for strain measurements or else using the same system for patient's follow up.
authors.affiliation: Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden.
authors.forename: Haki
authors.initials: H
authors.lastname: Jashari
authors.affiliation: Department of Clinical Sciences, Umeå University, Umeå, Sweden.
authors.forename: Annika
authors.initials: A
authors.lastname: Rydberg
authors.affiliation: Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden.
authors.forename: Pranvera
authors.initials: P
authors.lastname: Ibrahimi
authors.affiliation: Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden.
authors.forename: Gani
authors.initials: G
authors.lastname: Bajraktari
authors.affiliation: Department of Neonatology, Gynecology Clinic, University Clinical Center of Kosovo, Prishtina, Kosovo.
authors.forename: Lindita
authors.initials: L
authors.lastname: Kryeziu
authors.affiliation: Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden.
authors.forename: Fisnik
authors.initials: F
authors.lastname: Jashari
authors.affiliation: Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden. michael.henein@medicin.umu.se.
authors.forename: Michael Y
authors.initials: MY
authors.lastname: Henein
mesh_terms: D000293:Adolescent; D000375:Aging / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D004452:Echocardiography / Q000379:methods*; D055119:Elastic Modulus / Q000502:physiology; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D013318:Stroke Volume / Q000502:physiology; D016277:Ventricular Function, Left / Q000502:physiology*; D055815:Young Adult