Normal mature infants exhibit complex, nonlinear heart rhythms, whereas this nonlinearity is lacking in preterm infants, infants with clinical brain death, and those treated with atropine.
Observational
Does maturation and autonomic nervous system function affect the nonlinear complexity of heart rate variability in human infants?
The study demonstrates that the nonlinear complexity of heart rate variability in infants is dependent on autonomic nervous system maturation and function, being absent in prematurity, brain death, or parasympathetic blockade.
Nonlinear analyses of infant heart rhythms reveal a marked rise in the complexity of the electrocardiogram with maturation. We find that normal mature infants (gestation greater than or equal to 35 weeks) have complex and distinctly nonlinear heart rhythms (consistent with recent reports for healthy adults) but that such nonlinearity is lacking in preterm infants (gestation > or = to 27 weeks) where parasympathetic-sympathetic interaction and function are presumed to be less well developed. Our study further shows that infants with clinical brain death and those treated with atropine exhibit a similar lack of nonlinear feedback control. These three lines of evidence support the hypothesis championed by Goldberger et al. Goldberger, A.L., Rigney, D.R. & West, B.J. (1990) Sci. Am. 262, 43-49 that autonomic nervous system control underlies the nonlinearity and possible chaos of normal heart rhythms. This report demonstrates the acquisition of nonlinear heart rate dynamics and possible chaos in developing human infants and its loss in brain death and with the administration of atropine. It parallels earlier work documenting changes in the variability of heart rhythms in each of these cases and suggests that nonlinearity may provide additional power in characterizing physiological states.
Sugihara et al. (Tue,) conducted a observational in Infants. Maturation, brain death, or atropine treatment vs. Normal mature infants was evaluated on Nonlinear heart rate dynamics. Normal mature infants exhibit complex, nonlinear heart rhythms, whereas this nonlinearity is lacking in preterm infants, infants with clinical brain death, and those treated with atropine.