Heart Rate Variability in Healthy Six- to Sixteen-Year-Old Children

To study the age-related features of heart rate variability in children between the age of 6 to 16 years, cardiac rhythmograms of 5400 children were analyzed. It was found that parameters of the heart rate (M, SDNN, RMSSD, TF, VLF, and HF) in these children increase with age, changing in a wavelike way from year to year. Gender differences were observed in parameter M beginning from the age of 9; in parameters TF, VLF, and LF, the differences were observed beginning from the age of 11; and in parameters SDNN, RMSSD, and HF, the differences were observed from the age of 12 years. No differences between 16-year-old boys and girls in all the parameters of heart rate variability were found. It was shown that parameter VLF derived from ECG epochs of less than 5-min is suitable for physiological and clinical assessment. The obtained values of the parameters can be used in practice as reference standard.