Quantification of Scaling Exponents and Crossover Phenomena in Nonstationary
Heartbeat Time Series
C.-K. Peng, Shlomo Havlin, H. Eugene Stanley Ary L. Goldberger
Chaos 1995; 5:82-87
The healthy heartbeat is traditionally thought to be regulated
according to the classical principle of homeostasis whereby
physiologic systems operate to reduce variability and achieve an
equilibrium-like state [Physiol. Rev. 9, 399-431 (1929)]. However,
recent studies [Phys. Rev. Lett. 70, 1343-1346 (1993); Fractals in
Biology and Medicine (Birkhauser-Verlag, Basel, 1994), pp. 55-65]
reveal that under normal conditions, beat-to-beat fluctuations in
heart rate display the kind of long-range correlations typically
exhibited by dynamical systems far from equilibrium
[Phys. Rev. Lett. 59, 381-384 (1987)]. In contrast, heart rate time
series from patients with severe congestive heart failure show a
breakdown of this long-range correlation behavior. We describe a new
method--detrended fluctuation analysis (DFA)--for quantifying this
correlation property in non-stationary physiological time
series. Application of this technique shows evidence for a crossover
phenomenon associated with a change in short and long-range scaling
exponents. This method may be of use in distinguishing healthy from
pathologic data sets based on differences in these scaling properties.
Full Text: [ PDF (510 kB)]
Click here to
download the detrended fluctuation analysis (DFA) software package
discussed in this article.
