Heart rate variability by triangular index in infants exposed prenatally to cocaine.
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.
Mehta
Sudhir Ken
SK
Department of Pediatrics, MetroHealth Campus, Case Western Reserve University, Fairview Hospital, 18101 Lorain Avenue, Cleveland, Ohio 44111-5656, USA. ken.mehta@fairviewhospital.org
Super
Dennis M
DM
Salvator
Ann
A
Fradley
Linda Goetz
LG
Connuck
David
D
Kaufman
Elizabeth S
ES
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
D018765:Dopamine Uptake Inhibitors; D003042:Cocaine