title: Heart rate variability by triangular index in infants exposed prenatally to cocaine.
abstract: BACKGROUND
  In adults, heart rate variability triangular index (HRVi) is a highly reproducible measure of heart rate variability (HRV), which makes it more suitable for use in longitudinal studies. Although normative data have been published for newborns, studies in infants with pathological conditions are lacking.
  
  
  METHODS
  From 1997 to 2000, within the first 4 days of life, we prospectively evaluated HRVi in cocaine-exposed asymptomatic newborns (N = 97) by Holter monitoring. Their data were compared with infants from two control groups (one with no in utero drug exposure, N = 102; the other with exposure to alcohol, nicotine, or marijuana but no cocaine, N = 111).
  
  
  RESULTS
  In assessing concordance between and within operators for HRVi, the intraclass correlations were 0.983 (95% CI: 0.958, 0.994) and 0.997 (95% CI: 0.984, 0.999), respectively. Infants with in utero cocaine exposure had significantly (P < 0.0001) lower HRVi than those exposed to other drugs and to no drugs in utero. If abnormal HRVi is defined as < fifth percentile for the no drug exposed group (HRVi < 8), 10% of the cocaine-exposed newborns, in contrast to 2% in each of the control groups (P = 0.003) had abnormal values.
  
  
  CONCLUSIONS
  HRVi is a reliable measure to study heart rate variability in newborns. Asymptomatic infants with in utero cocaine exposure have lower HRVi. Our study supports the clinical use of an abnormal HRVi as a value < 8 for newborn infants.
authors.affiliation: Department of Pediatrics, MetroHealth Campus, Case Western Reserve University, Fairview Hospital, 18101 Lorain Avenue, Cleveland, Ohio 44111-5656, USA. ken.mehta@fairviewhospital.org
authors.forename: Sudhir Ken
authors.initials: SK
authors.lastname: Mehta
authors.forename: Dennis M
authors.initials: DM
authors.lastname: Super
authors.forename: Ann
authors.initials: A
authors.lastname: Salvator
authors.forename: Linda Goetz
authors.initials: LG
authors.lastname: Fradley
authors.forename: David
authors.initials: D
authors.lastname: Connuck
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Kaufman
mesh_terms: D001724:Birth Weight / Q000187:drug effects; D001830:Body Surface Area; D003042:Cocaine / Q000009:adverse effects / Q000494:pharmacology*; D019970:Cocaine-Related Disorders; D018765:Dopamine Uptake Inhibitors / Q000009:adverse effects / Q000494:pharmacology*; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D011248:Pregnancy Complications; D011297:Prenatal Exposure Delayed Effects; D011446:Prospective Studies; D015203:Reproducibility of Results
chemical_list: D018765:Dopamine Uptake Inhibitors; D003042:Cocaine