title: Myocardial function in term and preterm infants. Influence of heart size, gestational age and postnatal maturation.
abstract: BACKGROUND
  Sparse knowledge exists on the differences in cardiac function between term and preterm infants. This study examines the impact of heart size, gestational age and postnatal maturation on myocardial function.
  
  
  OBJECTIVE
  To assess and compare serial echocardiographic indices of myocardial function in term and moderately preterm infants.
  
  
  METHODS
  Longitudinal, prospective, observational echocardiographic cohort study of 45 healthy term infants examined at day three and at 12-20weeks postnatal age and 53 moderately preterm infants (gestational age 31-35weeks) examined at day three and at term equivalent (4-10weeks postnatal age).
  
  
  RESULTS
  Primary: Systolic mitral and tricuspid annular plane excursions and annular peak systolic pulsed wave tissue Doppler (pwTDI) velocities. Secondary: Indices normalized for heart size.
  
  
  RESULTS
  On day three, all indices were higher in the term than in the preterm infants whereas normalized systolic pwTDI velocities were lower in the term infants and normalized excursions showed no difference. All indices increased with advanced postnatal age. The indices in term infants on day three were lower than in preterm infants at term equivalent, with and without normalization. After postnatal maturation in both groups, all indices were higher in the term group (except left pwTDI), whereas normalized indices showed no consistent pattern.
  
  
  CONCLUSIONS
  Myocardial function indices increased with gestational age at birth and more profoundly with postnatal maturation. Serial examinations of non-normalized and normalized myocardial function indices showed no sustained differences between the preterm and the term infants. Normalization by heart size may be of value when assessing myocardial function in infants.
authors.affiliation: Department of Paediatrics, Møre and Romsdal Hospital Trust, NO-6026 Ålesund, Norway; Department of Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway. Electronic address: beate.h.eriksen@ntnu.no.
authors.forename: Beate Horsberg
authors.initials: BH
authors.lastname: Eriksen
authors.affiliation: Department of Paediatrics, Vestfold Hospital Trust, Tønsberg, Norway.
authors.forename: Eirik
authors.initials: E
authors.lastname: Nestaas
authors.affiliation: Department of Medicine, Møre and Romsdal Hospital Trust, Ålesund, Norway; Institute of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Torstein
authors.initials: T
authors.lastname: Hole
authors.affiliation: Institute of Informatics, University of Oslo, Norway.
authors.forename: Knut
authors.initials: K
authors.lastname: Liestøl
authors.affiliation: Department of Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway; Department of Cardiology, St. Olavs Hospital, Trondheim, Norway.
authors.forename: Asbjørn
authors.initials: A
authors.lastname: Støylen
authors.affiliation: Department of Neonatal Intensive Care, Oslo University Hospital, Ullevål, Oslo, Norway; Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.
authors.forename: Drude
authors.initials: D
authors.lastname: Fugelseth
mesh_terms: D015331:Cohort Studies; D004452:Echocardiography; D005865:Gestational Age; D006321:Heart / Q000033:anatomy & histology / Q000254:growth & development*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D008137:Longitudinal Studies; D009200:Myocardial Contraction / Q000502:physiology*; D009929:Organ Size; D011446:Prospective Studies
keywords: Echocardiography; Mitral annular plane systolic excursion; Postnatal transition; Tissue Doppler imaging; Tricuspid annular plane systolic excursion