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A multivariate time-frequency approach for tracking QT variability changes unrelated to heart rate variability

Orini, M; Taggart, P; Lambiase, PD; (2016) A multivariate time-frequency approach for tracking QT variability changes unrelated to heart rate variability. In: 2016 38th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC). (pp. pp. 924-927). IEEE Green open access

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Abstract

The beat-to-beat variability of the QT interval (QTV) is a marker of ventricular repolarization (VR) dynamics and it has been suggested as an index of sympathetic ventricular outflow and cardiac instability. However, QTV is also affected by RR (or heart rate) variability (RRV), and QTV due to RRV may reduce QTV specificity as a VR marker. Therefore, it would be desirable to separate QTV due to VR dynamics from QTV due to RRV. To do that, previous work has mainly focused on heart rate corrections or time-invariant autoregressive models. This paper describes a novel framework that extends classical multiple inputs/single output theory to the time-frequency (TF) domain to quantify QTV and RRV interactions. Quadratic TF distributions and TF coherence function are utilized to separate QTV into two partial (conditioned) spectra representing QTV related and unrelated to RRV, and to provide an estimates of intrinsic VR dynamics. In a simulation study, a time-varying ARMA model was used to generate signals representing realistic RRV and VR dynamics with controlled instantaneous frequencies and powers. The results demonstrated that the proposed methodology is able to accurately track changes in VR dynamics, with a correlation between theoretical and estimated patterns higher than 0.88. Data from healthy volunteers undergoing a tilt table test were analyzed and representative examples are discussed. Results show that the QTV unrelated to RRV dynamics quickly increased during orthostatic challenge.

Type: Proceedings paper
Title: A multivariate time-frequency approach for tracking QT variability changes unrelated to heart rate variability
Event: 38th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC’16)
Location: Orlando, Florida, United States
Dates: 16 August 2016 - 20 August 2016
ISBN-13: 9781457702204
Open access status: An open access version is available from UCL Discovery
DOI: 10.1109/EMBC.2016.7590852
Publisher version: http://ieeexplore.ieee.org/xpl/mostRecentIssue.jsp...
Language: English
Additional information: © 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
Keywords: Coherence, Time-frequency analysis, Correlation, Heart rate, Resonant frequency, Electrocardiography
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Institute of Cardiovascular Science
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Institute of Cardiovascular Science > Clinical Science
URI: https://discovery.ucl.ac.uk/id/eprint/1538533
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