title: Maturational Changes in Diastolic Longitudinal Myocardial Velocity in Preterm Infants.
abstract: BACKGROUND
  Doppler tissue imaging (DTI) has been used to evaluate myocardial velocity during ventricular filling, a means of characterizing diastolic function. Previous studies in older children have shown age-related increases in early diastolic tissue velocities, but there are limited data in preterm infants. The aim of this study was to prospectively determine maturational changes in diastolic tissue velocities at two points in time: (1) 7 days of age and (2) 36 weeks' postmenstrual age (PMA). It was further determined whether DTI measures were altered in infants who developed bronchopulmonary dysplasia with or without pulmonary hypertension.
  
  
  METHODS
  A total of 277 preterm infants born at <34 weeks' PMA, with birth weights between 500 and 1,250 g, were prospectively enrolled. Echocardiograms were obtained at 7 days of age and repeated at 36 weeks' PMA. Measurements included DTI assessment of early (E') and late (A') annular velocities of the left ventricular free wall, septum and the right ventricular free wall. Statistical analysis included the Wilcoxon rank sum test, simple linear regression, and the χ(2) test.
  
  
  RESULTS
  At 7 days of age, there was a statistically significant increase in the E'/A' ratio as a function of gestational age at birth. At 36 weeks' PMA, E'/A' ratio was increased, but there was no association with gestational age. DTI measures were not different between infants who did or did not develop bronchopulmonary dysplasia or pulmonary hypertension at either time point.
  
  
  CONCLUSIONS
  A gestational age-related increase was found in the early diastolic tissue velocities of preterm infants. At a gestational age equivalent to near term, no difference was observed in diastolic tissue velocities, regardless of gestational age at birth. These findings suggest that maturational changes in diastolic function occur relatively independently of the timing of birth.
authors.affiliation: Section of Cardiology, Pediatric Heart Lung Center, Department of Pediatrics, Children's Hospital Colorado, University of Colorado Denver, Anschutz School of Medicine, Aurora, Colorado. Electronic address: michael.dimaria@childrenscolorado.org.
authors.forename: Michael V
authors.initials: MV
authors.lastname: Di Maria
authors.affiliation: Section of Cardiology, Pediatric Heart Lung Center, Department of Pediatrics, Children's Hospital Colorado, University of Colorado Denver, Anschutz School of Medicine, Aurora, Colorado.
authors.forename: Adel K
authors.initials: AK
authors.lastname: Younoszai
authors.affiliation: Department of Epidemiology, University of Colorado Denver, Colorado School of Public Health, Aurora, Colorado.
authors.forename: Marci K
authors.initials: MK
authors.lastname: Sontag
authors.affiliation: Department of Epidemiology, University of Colorado Denver, Colorado School of Public Health, Aurora, Colorado.
authors.forename: Joshua I
authors.initials: JI
authors.lastname: Miller
authors.affiliation: Section of Neonatal-Perinatal Medicine, Department of Pediatrics, University of Indiana School of Medicine, Indianapolis, Indiana.
authors.forename: Brenda B
authors.initials: BB
authors.lastname: Poindexter
authors.affiliation: Section of Neonatal-Perinatal Medicine, Department of Pediatrics, University of Indiana School of Medicine, Indianapolis, Indiana.
authors.forename: David A
authors.initials: DA
authors.lastname: Ingram
authors.affiliation: Section of Pulmonary Medicine, Pediatric Heart Lung Center, Department of Pediatrics, Children's Hospital Colorado, University of Colorado Denver, Anschutz School of Medicine, Aurora, Colorado.
authors.forename: Steven H
authors.initials: SH
authors.lastname: Abman
authors.affiliation: Section of Critical Care, Pediatric Heart Lung Center, Department of Pediatrics, Children's Hospital Colorado, University of Colorado Denver, Anschutz School of Medicine, Aurora, Colorado.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Mourani
mesh_terms: D003971:Diastole; D018619:Echocardiography, Doppler, Pulsed / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000254:growth & development; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology*; D012189:Retrospective Studies; D016277:Ventricular Function, Left / Q000502:physiology*
keywords: Diastolic function; Preterm; Tissue Doppler