Asymmetric detrended fluctuation analysis reveals asymmetry in the rr intervals time series

In this paper we apply the Asymmetric Detrended Fluctuation Analysis to the RR intervals time series. The mathematical background of the ADFA method is discussed in the context of heart rate variability and heart rate asymmetry. We calculate the α^- and α⁺ ADFA scaling exponents for 100 RR intervals time series recorded in a group of healthy volunteers (20-40 years of age) with the use of the local ADFA. It is found that on average α⁺ < α^-, and that locally α^- dominates most of the time over α⁺ - both results are highly statistically significant.