Tilt-induced changes in f-wave characteristics during atrial fibrillation: an experimental and computational investigation

IntroductionThis study explores transient and stationary effects of sympathetic and parasympathetic stimulation on f-wave characteristics in atrial fibrillation (AF) patients undergoing a tilt test. Transient phase is defined as the initial 2-minute interval following each postural change, reflectin...

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Main Authors: Mostafa Abdollahpur, Chiara Celotto, Carlos Sánchez, Felix Plappert, Sten Östenson, Pyotr G. Platonov, Pablo Laguna, Esther Pueyo, Frida Sandberg
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-06-01
Series:Frontiers in Physiology
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Online Access:https://www.frontiersin.org/articles/10.3389/fphys.2025.1498426/full
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author Mostafa Abdollahpur
Chiara Celotto
Chiara Celotto
Carlos Sánchez
Carlos Sánchez
Felix Plappert
Sten Östenson
Pyotr G. Platonov
Pablo Laguna
Pablo Laguna
Esther Pueyo
Esther Pueyo
Frida Sandberg
author_facet Mostafa Abdollahpur
Chiara Celotto
Chiara Celotto
Carlos Sánchez
Carlos Sánchez
Felix Plappert
Sten Östenson
Pyotr G. Platonov
Pablo Laguna
Pablo Laguna
Esther Pueyo
Esther Pueyo
Frida Sandberg
author_sort Mostafa Abdollahpur
collection DOAJ
description IntroductionThis study explores transient and stationary effects of sympathetic and parasympathetic stimulation on f-wave characteristics in atrial fibrillation (AF) patients undergoing a tilt test. Transient phase is defined as the initial 2-minute interval following each postural change, reflecting immediate autonomic adaptation, whereas steady phase refers to the subsequent interval (from 3 minutes post-change until phase end) representing a stable autonomic state.MethodsOur primary aim is to investigate how the two branches of the autonomic nervous system (ANS) influence the f-wave frequency time series (f(m)). An analysis of f(m) in terms of the mean over time (Ff) and the magnitude of respiration-modulated f(m) variations (ΔFf) is conducted during baseline supine rest (B), head-down tilt (HDT) and head-up tilt (HUT). We analyzed data from a previous study in which 24 patients with persistent AF underwent a tilt test protocol, during which electrocardiograms (ECGs) were recorded. A model-based method was used to extract f(m) series from the ECG. Subsequently, an orthogonal subspace projection method was employed to quantify ΔFf, considering an ECG-derived respiratory signal. Electrophysiological computational simulations were conducted on 2D and 3D human atrial persistent AF models to aid the interpretation of clinical findings. Various levels of cholinergic stimulation by acetylcholine and β-adrenergic stimulation by isoproterenol were tested in the models. The temporal modulation of acetylcholine, representing changes associated with respiration, was cyclically modeled using sinusoidal waveforms.ResultsAnalysis of the clinical data showed a decrease in Ff from B to HDT and an increase from HDT to HUT. During HDT, ΔFf initially increased in the transient phase before decreasing in the steady phase, then rose again during HUT. Analysis of the simulated data showed that increasing the concentration of Isoproterenol and/or acetylcholine resulted in a rise in Ff. Additionally, the magnitude of ΔFf was shown to be associated with the extent of acetylcholine fluctuation.DiscussionThese results suggest that changes in f-wave frequency characteristics during HUT and HDT could be linked to changes in sympathetic activity, with parasympathetic activity possibly modulating the effects of sympathetic activity rather than being an independent driver of fibrillatory rate changes.
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spelling doaj-art-6ed4b5bb2d324f1a94e6c8817b9dc3422025-08-20T03:25:42ZengFrontiers Media S.A.Frontiers in Physiology1664-042X2025-06-011610.3389/fphys.2025.14984261498426Tilt-induced changes in f-wave characteristics during atrial fibrillation: an experimental and computational investigationMostafa Abdollahpur0Chiara Celotto1Chiara Celotto2Carlos Sánchez3Carlos Sánchez4Felix Plappert5Sten Östenson6Pyotr G. Platonov7Pablo Laguna8Pablo Laguna9Esther Pueyo10Esther Pueyo11Frida Sandberg12Department of Biomedical Engineering, Lund University, Lund, SwedenBSICoS Group, Aragon Institute of Engineering Research (I3A) and IIS Aragón, University of Zaragoza, Zaragoza, SpainCentro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Zaragoza, SpainBSICoS Group, Aragon Institute of Engineering Research (I3A) and IIS Aragón, University of Zaragoza, Zaragoza, SpainCentro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Zaragoza, SpainDepartment of Biomedical Engineering, Lund University, Lund, SwedenDepartment of Internal Medicine and Department of Clinical Physiology, Central Hospital Kristianstad, Kristianstad, SwedenDepartment of Cardiology, Clinical Sciences and Center for Integrative Electrocardiology at Lund University (CIEL), Lund, SwedenBSICoS Group, Aragon Institute of Engineering Research (I3A) and IIS Aragón, University of Zaragoza, Zaragoza, SpainCentro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Zaragoza, SpainBSICoS Group, Aragon Institute of Engineering Research (I3A) and IIS Aragón, University of Zaragoza, Zaragoza, SpainCentro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Zaragoza, SpainDepartment of Biomedical Engineering, Lund University, Lund, SwedenIntroductionThis study explores transient and stationary effects of sympathetic and parasympathetic stimulation on f-wave characteristics in atrial fibrillation (AF) patients undergoing a tilt test. Transient phase is defined as the initial 2-minute interval following each postural change, reflecting immediate autonomic adaptation, whereas steady phase refers to the subsequent interval (from 3 minutes post-change until phase end) representing a stable autonomic state.MethodsOur primary aim is to investigate how the two branches of the autonomic nervous system (ANS) influence the f-wave frequency time series (f(m)). An analysis of f(m) in terms of the mean over time (Ff) and the magnitude of respiration-modulated f(m) variations (ΔFf) is conducted during baseline supine rest (B), head-down tilt (HDT) and head-up tilt (HUT). We analyzed data from a previous study in which 24 patients with persistent AF underwent a tilt test protocol, during which electrocardiograms (ECGs) were recorded. A model-based method was used to extract f(m) series from the ECG. Subsequently, an orthogonal subspace projection method was employed to quantify ΔFf, considering an ECG-derived respiratory signal. Electrophysiological computational simulations were conducted on 2D and 3D human atrial persistent AF models to aid the interpretation of clinical findings. Various levels of cholinergic stimulation by acetylcholine and β-adrenergic stimulation by isoproterenol were tested in the models. The temporal modulation of acetylcholine, representing changes associated with respiration, was cyclically modeled using sinusoidal waveforms.ResultsAnalysis of the clinical data showed a decrease in Ff from B to HDT and an increase from HDT to HUT. During HDT, ΔFf initially increased in the transient phase before decreasing in the steady phase, then rose again during HUT. Analysis of the simulated data showed that increasing the concentration of Isoproterenol and/or acetylcholine resulted in a rise in Ff. Additionally, the magnitude of ΔFf was shown to be associated with the extent of acetylcholine fluctuation.DiscussionThese results suggest that changes in f-wave frequency characteristics during HUT and HDT could be linked to changes in sympathetic activity, with parasympathetic activity possibly modulating the effects of sympathetic activity rather than being an independent driver of fibrillatory rate changes.https://www.frontiersin.org/articles/10.3389/fphys.2025.1498426/fullatrial fibrillationautonomic nervous systemECG processingf-wave frequencyparasympathetic regulationrespiratory modulation
spellingShingle Mostafa Abdollahpur
Chiara Celotto
Chiara Celotto
Carlos Sánchez
Carlos Sánchez
Felix Plappert
Sten Östenson
Pyotr G. Platonov
Pablo Laguna
Pablo Laguna
Esther Pueyo
Esther Pueyo
Frida Sandberg
Tilt-induced changes in f-wave characteristics during atrial fibrillation: an experimental and computational investigation
Frontiers in Physiology
atrial fibrillation
autonomic nervous system
ECG processing
f-wave frequency
parasympathetic regulation
respiratory modulation
title Tilt-induced changes in f-wave characteristics during atrial fibrillation: an experimental and computational investigation
title_full Tilt-induced changes in f-wave characteristics during atrial fibrillation: an experimental and computational investigation
title_fullStr Tilt-induced changes in f-wave characteristics during atrial fibrillation: an experimental and computational investigation
title_full_unstemmed Tilt-induced changes in f-wave characteristics during atrial fibrillation: an experimental and computational investigation
title_short Tilt-induced changes in f-wave characteristics during atrial fibrillation: an experimental and computational investigation
title_sort tilt induced changes in f wave characteristics during atrial fibrillation an experimental and computational investigation
topic atrial fibrillation
autonomic nervous system
ECG processing
f-wave frequency
parasympathetic regulation
respiratory modulation
url https://www.frontiersin.org/articles/10.3389/fphys.2025.1498426/full
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