Heart rate variability in cocaine-exposed newborn infants.
BACKGROUND
Infants born to cocaine-using mothers have a 3- to 8-fold increase in sudden infant death syndrome. Its underlying cause, in part, may be attributed to abnormal autonomic function. We proposed to study heart rate variability, reflecting autonomic control of the heart, in cocaine-exposed infants.


METHODS
From 1997 to 2000, we studied 217 asymptomatic, term infants, of whom 68 had intrauterine cocaine exposure (group I). Their data were compared with infants exposed to drugs other than cocaine (group II, n = 77) and no drugs (group III, n = 72). Twenty-four-hour heart rate variability was measured within 72 hours of birth.


RESULTS
Cocaine-exposed infants, as compared with the 2 control groups, had an overall significant decrease (P <.05) in global heart rate variability and a lower standard deviation of all valid N-N intervals in the recording (41.9 +/- 1.4 ms vs 47.6 +/- 1.3 ms and 46.9 +/- 1.3 ms, respectively). Vagal parameters such as high-frequency power and the square root of the mean of the squared differences between adjacent N-N intervals were also lower in newborns with heavy in utero cocaine exposure.


CONCLUSIONS
Decreased heart rate variability was seen in cocaine-exposed infants. Whether low heart rate variability is a marker for increased risk of sudden death in infants (as it is in adults with structural heart disease) is unknown and requires further investigation.
Mehta
S K
SK
Fairview Hospital and MetroHealth Medical Center, Department of Pediatrics and Heart and Vascular Center, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio 44111-5656, USA. ken.mehta@fairviewhospital.org
Super
D M
DM
Salvator
A
A
Singer
L
L
Connuck
D
D
Fradley
L G
LG
Harcar-Sevcik
R A
RA
Kaufman
E S
ES
D003042:Cocaine / Q000009:adverse effects*; D019970:Cocaine-Related Disorders / Q000150:complications*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn / Q000502:physiology*; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D011248:Pregnancy Complications / Q000503:physiopathology*; D012307:Risk Factors; D013398:Sudden Infant Death / Q000209:etiology
D003042:Cocaine