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.

Neonatal behavioral profile of the offspring of women who continued to exercise regularly throughout pregnancy.

OBJECTIVE: The objective of the study was to test the hypothesis that continuing regular exercise throughout pregnancy alters early neonatal behavior. STUDY DESIGN: The offspring of 34 women who exercised were compared with those of 31 demographically similar control subjects. All women had normal antenatal courses. Behavior was assessed at 5 days after birth with the Brazelton Scales. RESULTS: The offspring of the exercising women performed better in 2 of the 6 behavioral constellations when examined at 5 days after birth. The scores reflecting their ability to orient to environmental stimuli were (mean +/- SEM) 7.6 +/- 0.1 and 6.5 +/- 0. 3, respectively, and the scores reflecting their ability to regulate their state or quiet themselves after sound and light stimuli were 6. 6 +/- 0.2 and 4.9 +/- 0.3, respectively. The scores reflecting habituation (7.9 +/- 0.2 and 8.0 +/- 0.1, respectively), motor organization (5.7 +/- 0.1 and 5.5 +/- 0.1, respectively), autonomic stability (5.9 +/- 0.2 and 5.5 +/- 0.3, respectively), and behavioral state range (4.1 +/- 0.2 and 4.5 +/- 0.3, respectively) were not significantly different. CONCLUSIONS: These data indicate that the neonates born of exercising mothers have a different neurobehavioral profile as early as the fifth day after birth.

The one-year morphometric and neurodevelopmental outcome of the offspring of women who continued to exercise regularly throughout pregnancy.

OBJECTIVE: Our purpose was to test the hypothesis that continuing regular exercise throughout pregnancy alters morphometric and neurodevelopmental outcome at 1 year. STUDY DESIGN: The offspring of 52 women who exercised were compared with those of 52 control subjects who were similar in terms of multiple prenatal and postnatal variables known to influence outcome. All women were enrolled before pregnancy and had clinically normal antenatal and postnatal courses. Neurodevelopment was assessed by blinded examiners at 1 year of age, and morphometrics were obtained at birth and at 1 year of age. RESULTS: At birth, the offspring of the exercising women weighed less (3.38 +/- 0.06 kg vs 3.58 +/- 0.07 kg) and had less body fat (9.5% +/- 0.8% vs 12.6% +/- 0.6%). However, at 1 year, all morphometric parameters were similar, and no clinically significant between-group differences were observed in performance on either the Bayley psychomotor (108 +/- 1 vs 101 +/- 2) or mental (120 +/- 1 vs 118 +/- 1) scales. CONCLUSIONS: These data indicate that the offspring of exercising mothers have normal growth and development during the first year of life.

Parental hypertension and cardiac alterations in normotensive children and adolescents.

The objective of this investigation was the examination of the relation of left ventricular mass (LVM) and function with cardiovascular response to exercise in normotensive adolescents at risk for hypertension. Carried out was a prospective, cross-sectional study of 47 subjects (age, 10 to 18 years), who underwent dynamic and isometric exercise, 24-hour Holter monitoring, and echocardiography. Twenty-nine had normotensive parents (group 2, "at risk"). Both groups were similar for age, race, sex, body mass index, blood pressures, and resting heart rates. Group 2 had a higher E/A ratio (2.3 +/- 0.5 vs 2.0 +/- 0.5; p = 0.039) and higher heart rates during stage IV of dynamic exercise (188 +/- 20 beats/min vs 176 +/- 18 beats/min; p = 0.046). The LVM, 24-hour heart rates, and exercise systolic blood pressures (SBP) were similar in both groups. Only in group 2, SBP at peak dynamic and isometric exercise correlated best with LVM (r = 0.74, p < 0.002; r = 0.82, p < 0.001). It is concluded that altered hemodynamic regulatory mechanisms may exist before the establishment of hypertension in normotensive subjects with parental hypertension.

Transient myocardial ischemia in infants prenatally exposed to cocaine.

This prospective study examined whether neonates of pregnant women who used cocaine during pregnancy are at a risk for the development of transient myocardial ischemia and altered autonomic function, as in adults. We studied 21 of 35 infants with a history of prenatal exposure to cocaine. The ST segment changes and heart rate variability were evaluated from three-channel Holter monitors within 48 hours of birth. The data were compared with those on 20 control infants with similar birth weight, gestational age, and postnatal age. Six infants (29%) who were exposed to cocaine in utero had transient ST segment elevation, versus only one infant (5%) from the control group (odds ratio = 7.6; 95% confidence interval, 1.14, 50.64). Heart rates, results of total power and low-frequency power spectral analyses for heart rate variability, and arrhythmias were not significantly different in the two groups. However, a lower ratio of low-to high-frequency power reflected increased vagal activity in cocaine-exposed infants. We conclude that cocaine use in pregnant mothers is associated with transient ST segment abnormalities in their infants. These abnormalities are consistent with transient myocardial ischemia.