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Open AccessFeature PaperArticle

Introducing BisQ, A Bicoherence-Based Nonlinear Index to Explore the Heart Rhythm

1
Cuban Center for Neurosciences, La Habana 11600, Cuba
2
Department of Neurophysiology and Pathophysiology, University Medical Center, Hamburg-Eppendorf, Martinistraße 52, 20251 Hamburg, Germany
*
Authors to whom correspondence should be addressed.
Math. Comput. Appl. 2020, 25(3), 45; https://doi.org/10.3390/mca25030045
Received: 2 July 2020 / Revised: 16 July 2020 / Accepted: 16 July 2020 / Published: 18 July 2020
(This article belongs to the Special Issue Heart Rate Variability: Algorithms and Software Tools)
Nonlinear frequency coupling is assessed with bispectral measures, such as bicoherence. In this study, BisQ, a new bicoherence-derived index, is proposed for assessing nonlinear processes in cardiac regulation. To find BisQ, 110 ten-minute ECG traces obtained from 55 participants were initially studied. Via bispectral analysis, a bicoherence matrix (BC) was obtained from each trace (0.06 to 1.8 Hz with a resolution of 0.01 Hz). Each frequency pair in BC was tested for correlation with the HRV recurrent quantification analysis (RQA) index Lmean, obtained from tachograms from the same ECG trace. BisQ is the result of adding BC values corresponding to the three frequency pairs exhibiting the highest correlation with Lmean. BisQ values were estimated for different groups of subjects: healthy persons, persons with arrhythmia, persons with epilepsy, and preterm neonates. ECG traces from persons with arrhythmia showed no significant differences in BisQ values respect to healthy persons, while persons with epilepsy and neonates showed higher BisQ values (p < 0.05; Mann-Whitney U-test). BisQ reflects nonlinear interactions at the level of sinus-and atrial-ventricular nodes, and most likely cardiorespiratory coupling as well. We expect that BisQ will allow for further exploration of cardiac nonlinear dynamics, complementing available HRV indices. View Full-Text
Keywords: electrocardiogram; heart rate variability; bispectrum; recurrent quantification analysis; arrhythmia; epilepsy electrocardiogram; heart rate variability; bispectrum; recurrent quantification analysis; arrhythmia; epilepsy
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MDPI and ACS Style

Hernández-Caceres, J.L.; González-Fernández, R.I.; Ontivero-Ortega, M.; Nolte, G. Introducing BisQ, A Bicoherence-Based Nonlinear Index to Explore the Heart Rhythm. Math. Comput. Appl. 2020, 25, 45. https://doi.org/10.3390/mca25030045

AMA Style

Hernández-Caceres JL, González-Fernández RI, Ontivero-Ortega M, Nolte G. Introducing BisQ, A Bicoherence-Based Nonlinear Index to Explore the Heart Rhythm. Mathematical and Computational Applications. 2020; 25(3):45. https://doi.org/10.3390/mca25030045

Chicago/Turabian Style

Hernández-Caceres, José L.; González-Fernández, René I.; Ontivero-Ortega, Marlis; Nolte, Guido. 2020. "Introducing BisQ, A Bicoherence-Based Nonlinear Index to Explore the Heart Rhythm" Math. Comput. Appl. 25, no. 3: 45. https://doi.org/10.3390/mca25030045

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