Fractal and nonlinear changes in the long-term baseline fluctuations of fetal heart rate.

Autor: Echeverría JC; Basic Science and Engineering Division, Universidad Autónoma Metropolitana-Izt., San Rafael Atlixco ♯186, C.P. 09340, Mexico City, Mexico. jcea@xanum.uam.mx, Álvarez-Ramírez J, Peña MA, Rodríguez E, Gaitán MJ, González-Camarena R
Jazyk: angličtina
Zdroj: Medical engineering & physics [Med Eng Phys] 2012 May; Vol. 34 (4), pp. 466-71. Date of Electronic Publication: 2011 Sep 01.
DOI: 10.1016/j.medengphy.2011.08.006
Abstrakt: The interpretation of heart rate patterns obtained by fetal monitoring relies on the definition of a baseline, which is considered as the running average heart rate in the absence of external stimuli during periods of fetal rest. We present a study along gestation of the baseline's fluctuations, in relation to fractal and nonlinear properties, to assess these fluctuations according with time-varying attracting levels introduced by maturing regulatory mechanisms. A low-risk pregnancy was studied weekly from the 17th to 38th week of gestation during long-term recording sessions at night (>6 h). Fetal averaged pulse rate samples and corresponding baseline series were obtained from raw abdominal ECG ambulatory data. The fractal properties of these series were evaluated by applying detrended fluctuation analysis. The baseline series were also explored to evaluate nonlinear properties and time ordering by applying the scaling magnitude and sign analyses. Our main findings are that the baseline shows fractal and even nonlinear anticorrelated fluctuations. This condition was specially the case before mid-gestation, as revealed by α values near to unit, yet becoming significantly more complex after 30 weeks of gestation as indicated by α(mag) values >0.5. The structured (i.e. not random) fluctuations and particular nonlinear changes that we found thus suggest that the baseline provides on itself information concerning the functional integration of cardiac regulatory mechanisms.
(Copyright © 2011 IPEM. Published by Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
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