Complexity of Atrial Fibrillation Electrograms Through Nonlinear Signal Analysis: In Silico Approach

Tobón, Catalina; Duque, Andrés; Ugarte, Juan; MiguelBecerra,; Sáiz, Javier

doi:10.5772/intechopen.69475

Cited by 2 publications

(2 citation statements)

References 133 publications

(203 reference statements)

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“…The interest in rotor dynamics research has increased since clinical reports claim that rotor ablation improves the rates of success in human CAF treatment (Narayan et al, 2012 ). Using in silico models, mechanistic explanations and therapeutic approaches have been tested (Zhao et al, 2015 ; Berenfeld, 2016 ; Guillem et al, 2016 ; Tobón et al, 2017 ). In this work, we assessed the effect of structural heterogeneities on rotor propagation by varying the complex derivative order γ.…”

Section: Discussionmentioning

confidence: 99%

Atrial Rotor Dynamics Under Complex Fractional Order Diffusion

et al. 2018

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The mechanisms of atrial fibrillation (AF) are a challenging research topic. The rotor hypothesis states that the AF is sustained by a reentrant wave that propagates around an unexcited core. Cardiac tissue heterogeneities, both structural and cellular, play an important role during fibrillatory dynamics, so that the ionic characteristics of the currents, their spatial distribution and their structural heterogeneity determine the meandering of the rotor. Several studies about rotor dynamics implement the standard diffusion equation. However, this mathematical scheme carries some limitations. It assumes the myocardium as a continuous medium, ignoring, therefore, its discrete and heterogeneous aspects. A computational model integrating both, electrical and structural properties could complement experimental and clinical results. A new mathematical model of the action potential propagation, based on complex fractional order derivatives is presented. The complex derivative order appears of considering the myocardium as discrete-scale invariant fractal. The main aim is to study the role of a myocardial, with fractal characteristics, on atrial fibrillatory dynamics. For this purpose, the degree of structural heterogeneity is described through derivatives of complex order γ = α + jβ. A set of variations for γ is tested. The real part α takes values ranging from 1.1 to 2 and the imaginary part β from 0 to 0.28. Under this scheme, the standard diffusion is recovered when α = 2 and β = 0. The effect of γ on the action potential propagation over an atrial strand is investigated. Rotors are generated in a 2D model of atrial tissue under electrical remodeling due to chronic AF. The results show that the degree of structural heterogeneity, given by γ, modulates the electrophysiological properties and the dynamics of rotor-type reentrant mechanisms. The spatial stability of the rotor and the area of its unexcited core are modulated. As the real part decreases and the imaginary part increases, simulating a higher structural heterogeneity, the vulnerable window to reentrant is increased, as the total meandering of the rotor tip. This in silico study suggests that structural heterogeneity, described by means of complex order derivatives, modulates the stability of rotors and that a wide range of rotor dynamics can be generated.

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Section: Discussionmentioning

confidence: 99%

Atrial Rotor Dynamics Under Complex Fractional Order Diffusion

et al. 2018

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“…A unipolar electrogram (EGM) for a sheet of cells under the condition of uniform intracellular anisotropic resistivity was simulated as previously described. 45 The extracellular potential (V e ) is given by the following equation:…”

Section: Simulated Pseudo-unipolar Electrogramsmentioning

confidence: 99%

Fibrillatory conduction in a simulated two-dimensional model of human atrial tissue: effect of the interaction of two ectopic foci

Tobón¹,

Sáiz

2018

SIMULATION

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Atrial fibrillation (AF) is the most common tachyarrhythmia. It has been demonstrated that extra-stimuli could act as triggers for AF. In many patients it is possible that multiple ectopic foci co-exist, and their interactions may generate complex conduction patterns. Our goal is to investigate the influence of the focus frequency, conduction velocity, and anisotropy on fibrillatory pattern generation during the interaction of multiple ectopic activities under electrical remodeling conditions. Our results support the broadly accepted theory that ectopic activity acting in remodeled tissue is an initiator of reentrant mechanisms. These reentrant circuits can generate fibrillatory activity when interacting with other rapid ectopic foci and under the following conditions: high ectopic focus frequency, slow conduction velocity, and anisotropic tissue. Analyses of electrogram polymorphism allow determination of which zones of tissue permit one to know in which zone of tissue unstable activity exists. Our results give useful insights into the electrophysiological parameters that determine the initiation and maintenance of fibrillatory conduction by two ectopic foci interaction in a simulated two-dimensional sheet of human atrial cells, under chronic AF conditions.

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Complexity of Atrial Fibrillation Electrograms Through Nonlinear Signal Analysis: In Silico Approach

Cited by 2 publications

References 133 publications

Atrial Rotor Dynamics Under Complex Fractional Order Diffusion

Atrial Rotor Dynamics Under Complex Fractional Order Diffusion

Fibrillatory conduction in a simulated two-dimensional model of human atrial tissue: effect of the interaction of two ectopic foci

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