title: Assessment of myocardial function in preterm infants with chronic lung disease using tissue Doppler imaging.
abstract: OBJECTIVE
  To assess myocardial function and presence of pulmonary hypertension (PH) using both tissue Doppler imaging (TDI) and conventional echocardiography in preterm infants of <32 weeks gestation with chronic lung disease (CLD).
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  Tertiary neonatal intensive care unit.
  
  
  METHODS
  Three groups of preterm infants were recruited. Group 1-CLD receiving positive pressure airway support including high-flow humidified nasal cannula oxygen (n=25), group 2-CLD receiving low-flow nasal oxygen (n=25) and group 3-no CLD (n=22).
  
  
  METHODS
  Echocardiography was performed around 36 weeks corrected gestational age. Myocardial function and PH were assessed using both conventional (left ventricular fractional shortening (LVFS) and left ventricular output (LVO), tricuspid regurgitation and ventricular septal flattening) and TDI techniques (myocardial velocities, myocardial performance index (MPI) and right ventricular isovolumetric relaxation time (RV-IVRT)).
  
  
  RESULTS
  The MPI of right ventricle (RV) and left ventricle (LV) was significantly higher in CLD infants: mean RV MPI group 1-0.79, group 2-0.65 and group3-0.52. LV MPI: group 1-0.77, group 2-0.70 and group 3-0.45. There was a trend towards higher MPIs in group 1 compared with group 2. LVFS and LVO were similar across all three groups. RV-IVRT was also significantly higher in infants with CLD infants (group 1-64 milliseconds, group 2-62 milliseconds and group 3-52 milliseconds). PH was not detected by conventional echocardiography.
  
  
  CONCLUSIONS
  Infants with CLD have evidence of relative biventricular dysfunction and higher pulmonary arterial blood pressure as demonstrated by TDI, which were not detected by conventional echocardiography.
authors.affiliation: Department of Neonatology, Liverpool Women's Hospital NHS Foundation Trust, Liverpool, UK.
authors.forename: Phani Kiran
authors.initials: PK
authors.lastname: Yajamanyam
authors.affiliation: Department of Neonatology, Birmingham Women's Hospital NHS Foundation Trust, Birmingham, UK.
authors.forename: Robert J S
authors.initials: RJS
authors.lastname: Negrine
authors.affiliation: Department of Neonatology, Birmingham Women's Hospital NHS Foundation Trust, Birmingham, UK.
authors.forename: Shree Vishna
authors.initials: SV
authors.lastname: Rasiah
authors.affiliation: Clinical Biostatistics Unit, Hospital Ramon y Cajal (IRYCIS-CIBERESP), Madrid, Spain.|Women's Health Research Unit, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: Javier
authors.initials: J
authors.lastname: Zamora
authors.affiliation: Department of Neonatology, Birmingham Women's Hospital NHS Foundation Trust, Birmingham, UK.|Institute of Metabolism and Systems Research, University of Birmingham, UK.
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Ewer
keywords: Neonatology; Preterm infants; echocardiography