[Heart rhythm variability of healthy newborns with congenital heart defects].

Short-term changes in heart rate (heart rate variability) are seen at every age and represent an important sign of normal homeostatic mechanisms of the cardiovascular system. The influence of premature birth on the maturation of the autonomic nervous system was established by studying heart rate variability in 12 pre-term newborns. The results were compared with a group of 88 full-term newborns and with a group of 14 newborns with congenital heart defects. Heart rate variability was measured by spectral- and time-domain analysis of interbeat intervals in 4-hour continuous ECG recordings. In comparison with full-term newborns, pre-term newborns had significantly lower (p < 0.05) time-domain indices (SDNN = 42.73 vs. 53.38; SDANN-i = 29.84 vs. 35.7) and spectral-domain indices (ULF = 7.91 vs. 10.29; VLF = 20.28 vs. 27.42; LF = 12.57 vs. 16.46). The present results point to a significant influence of gestational age on heart rate variability. Newborns with congenital heart defects present a different pattern of activity of the autonomic nervous system.