## Abstract

The fractal structure of heart rate is usually quantified by estimating a short-term (α_{1}) and a long-term (α_{2}) scaling exponent by Detrended Fluctuations Analysis (DFA). Evidence, however, has been provided that heart rate is a multifractal signal, better characterized by a large number of scaling exponents. Aim of this study is to verify whether two scaling exponents only from DFA provide a sufficiently accurate description of the possibly multifractal nature of cardiovascular signals. We measured ECG and finger arterial pressure in 33 volunteers for 10 minutes during each of 3 conditions: supine rest (SUP); sitting at rest (SIT); light physical exercise (EXE). DFA was applied on the beat-by-beat series of R-R interval (RRI) and mean arterial pressure (MAP). We then computed the local scaling exponent α(n), defined as the slope of the detrended fluctuation function F(n) around the beat scale n, in a log-log plot. If α_{1} and α_{2} correctly model the multiscale structure of blood pressure and heart rate, we should find that α(n) is constant over a short-term and a long-term range of beat scales. Results show that only the long-term α_{2} exponent provides a relatively good approximation of the multiscale structure of RRI and MAP. Moreover, posture and physical activity have important effects on local scaling exponents, and on the range of beat scales n where α(n) can be approximated by a constant α_{2} coefficient.

Original language | English |
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Title of host publication | Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings |

Pages | 5035-5038 |

Number of pages | 4 |

DOIs | |

Publication status | Published - 2007 |

Event | 29th Annual International Conference of IEEE-EMBS, Engineering in Medicine and Biology Society, EMBC'07 - Lyon, France Duration: Aug 23 2007 → Aug 26 2007 |

### Other

Other | 29th Annual International Conference of IEEE-EMBS, Engineering in Medicine and Biology Society, EMBC'07 |
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Country/Territory | France |

City | Lyon |

Period | 8/23/07 → 8/26/07 |

## ASJC Scopus subject areas

- Biomedical Engineering