Time and spectral domain heart rate variability (HRV) analysis in healthy children

The aim of this study was to determine HRV normal values in healthy children. Material: 175 patients (pts) aged from 4 to 18 years (ys), 87 girls, 88 boys. According to the age all children were divided in 4 groups: group 1: 27 pts from 4 to 7 ys, group 2- 64 pts from 7 to II ys, group 3- 58 pts from II to 15 ys, group 4- 26 pts from 15 to 18 ys. On time domain we analysed in ms: mean RR, SDNN, SDNN-i, SDANN-i, rMSSD and in % pNN50. Spectral analysis was performed using algorithm FFT from short- term (5 minutes) recording during day and night. The following parameters were calculated: VLF- very low frequency (0,0033- 0,04 Hz), LF- low frequency (0,04- 0,15 Hz), HF- high frequency (0,15- 0,4 Hz), TP- total power (0,0033- 0,4 Hz), ratio LF/HF, in following unites: ms(2), logarithm natural (In), normalised unites (nu). mRR, SDNN nad SDANNi, LF (ms(2), In, nu during day) was significantly higher with age. HF nu value in group I during the day as well as at night were significantly higher than in group 4. LF/ HF ratio were statistically different between groups I & 4 and 2 & 4. Conclusion: 1.LF during the day were age dependent.