Arrhythmogenic role of the border between two areas of cardiac cell alignment

Kudryashova, Nina; Teplenin, Alexander; Orlova, Yu. V.; Selina, L.V.; Agladze, Konstantin

doi:10.1016/j.yjmcc.2014.09.003

Cited by 10 publications

(9 citation statements)

References 37 publications

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“…Such a change in resistivity naturally occurs due to tissue anisotropy and can potentially result in a propagation block. This was demonstrated in our previous study [ 18 ] in experiments with a cell culture of neonatal rat myocytes, and numerically in a low dimensional model for cardiac tissue. Here, we extended the theoretical study to a detailed ionic model of human cardiac cells.…”

Section: Introductionsupporting

confidence: 56%

“…In this paper, we performed a detailed study of waveblock formation at the anisotropic boundary. Although this system was already studied using a low dimensional model of a cardiac cell [ 18 ], we used an ionic model for human cardiac tissue for the first time to describe the system of abrupt changes in fiber orientation. In addition, we studied in detail how the formation of the waveblock depends on both the period of stimulation and the conductivity of different ionic currents.…”

Section: Discussionmentioning

confidence: 99%

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Conditions for Waveblock Due to Anisotropy in a Model of Human Ventricular Tissue

et al. 2015

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Waveblock formation is the main cause of reentry. We have performed a comprehensive numerical modeling study of block formation due to anisotropy in Ten Tusscher and Panfilov (2006) ionic model for human ventricular tissue. We have examined the border between different areas of myocardial fiber alignment and have shown that blockage can occur for a wave traveling from a transverse fiber area to a longitudinal one. Such blockage occurs for reasonable values of the anisotropy ratio (AR): from 2.4 to 6.2 with respect to propagation velocities. This critical AR decreases by the suppression of I Na and I Ca, slightly decreases by the suppression of I Kr and I Ks, and substantially increases by the suppression of I K1. Hyperkalemia affects the block formation in a complex, biphasic way. We provide examples of reentry formation due to the studied effects and have concluded that the suppression of I K1 should be the most effective way to prevent waveblock at the areas of abrupt change in anisotropy.

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Section: Introductionsupporting

confidence: 56%

Section: Discussionmentioning

confidence: 99%

Conditions for Waveblock Due to Anisotropy in a Model of Human Ventricular Tissue

et al. 2015

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“…Our analysis emphasizes the important role of the FPR as the nucleation center for reentry in contrast to the common expectation that a wave break occurs at the boundary between an excitable and unexcitable region. Please note that a possibility to initiate a permanent reentry activity after a single stimulation was also demonstrated in a much less generic reaction-diffusion system (29,30) and in a strongly anisotropic 2D tissue (31,32). In a medium with a nonlocalized inhomogeneity, a creation of a drifting spiral wave, which disappears after several rotations, has been reported (25).…”

Section: Discussionmentioning

confidence: 90%

Fast propagation regions cause self-sustained reentry in excitable media

Zykov

Krekhov

Bodenschatz

2017

Proc. Natl. Acad. Sci. U.S.A.

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Self-sustained waves of electrophysiological activity can cause arrhythmia in the heart. These reentrant excitations have been associated with spiral waves circulating around either an anatomically defined weakly conducting region or a functionally determined core. Recently, an ablation procedure has been clinically introduced that stops atrial fibrillation of the heart by destroying the electrical activity at the spiral core. This is puzzling because the tissue at the anatomically defined spiral core would already be weakly conducting, and a further decrease should not improve the situation. In the case of a functionally determined core, an ablation procedure should even further stabilize the rotating wave. The efficacy of the procedure thus needs explanation. Here, we show theoretically that fundamentally in any excitable medium a region with a propagation velocity faster than its surrounding can act as a nucleation center for reentry and can anchor an induced spiral wave. Our findings demonstrate a mechanistic underpinning for the recently developed ablation procedure. Our theoretical results are based on a very general and widely used two-component model of an excitable medium. Moreover, the important control parameters used to realize conditions for the discovered phenomena are applicable to quite different multicomponent models.excitable media | spirals | reentry | cardiology | ablation I n their seminal theoretical work, Norbert Wiener and Arturo Rosenblueth (1) showed in 1946 that the self-sustained activity in the cardiac muscle can be associated with an excitation wave rotating around an obstacle. This mechanism has since been very successfully applied to the understanding of the generation and control of malignant electrical activity in the heart (2). It is also well known that self-sustained excitation waves, called spirals, can exist in homogeneous excitable media. It has been demonstrated that spirals rotating within a homogeneous medium or anchored at an obstacle are generically expected for any excitable medium. Examples are known in myocardial tissues and the mammalian brain (3, 4), in the aggregation of amoeba colonies (5), in autocatalytic chemical reactions (6, 7), and in the spreading depression in chicken retina (8), as well as in the catalytic reactions of carbon monoxide gas on a platinum surface (9) and also in intracellular calcium dynamics (10). Spirals have important consequences for medicine, where they are known to cause sudden cardiac death (11,12). Recently, an atrial defibrillation procedure was clinically introduced that locates the spiral core region by detecting the phase-change point trajectories of the electrophysiological wave field and then, by ablating that region, restores sinus rhythm (13,14). This is clearly at odds with the Wiener-Rosenblueth mechanism because a further destruction of the tissue near the spiral core should not improve the situation.Here, we show theoretical results that help to resolve this issue. We found that spirals can be anchored not only at an o...

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“…The results presented here are quantitatively consistent with those earlier results (Figures 11 , 12 ), indicating that a sharp increase in λ by more than 30–40% in the direction of propagation may lead to block during premature stimulation or under conditions of reduced excitability. It seems that the threshold for block is independent of the cellular mechanism causing the change in space constant (gap junction conductance, cell size, myofibroblast density), and may apply to other situations in which cellular and/or tissue remodeling results in a change of λ For instance, it may explain the conditions for block at the border between two regions with different fiber alignments (Kudryashova et al, 2014 ). Block would be expected at a transition from a region where propagation occurs in the direction transverse to the fiber orientation (λ in the direction of propagation = λ Trans ) to a region where propagation occurs in the direction longitudinal to the fiber orientation (λ in the direction of propagation = λ Long ), if λ Long /λ Trans > 1.40.…”

Section: Discussionmentioning

confidence: 99%

Dynamics of propagation of premature impulses in structurally remodeled infarcted myocardium: a computational analysis

Cabo

2014

Front. Physiol.

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Initiation of cardiac arrhythmias typically follows one or more premature impulses either occurring spontaneously or applied externally. In this study, we characterize the dynamics of propagation of single (S2) and double premature impulses (S3), and the mechanisms of block of premature impulses at structural heterogeneities caused by remodeling of gap junctional conductance (Gj) in infarcted myocardium. Using a sub-cellular computer model of infarcted tissue, we found that |INa,max|, prematurity (coupling interval with the previous impulse), and conduction velocity (CV) of premature impulses change dynamically as they propagate away from the site of initiation. There are fundamental differences between the dynamics of propagation of S2 and S3 premature impulses: for S2 impulses |INa,max| recovers fast, prematurity decreases and CV increases as propagation proceeds; for S3 impulses low values of |INa,max| persist, prematurity could increase, and CV could decrease as impulses propagate away from the site of initiation. As a consequence it is more likely that S3 impulses block at sites of structural heterogeneities causing source/sink mismatch than S2 impulses block. Whether premature impulses block at Gj heterogeneities or not is also determined by the values of Gj (and the space constant λ) in the regions proximal and distal to the heterogeneity: when λ in the direction of propagation increases >40%, premature impulses could block. The maximum slope of CV restitution curves for S2 impulses is larger than for S3 impulses. In conclusion: (1) The dynamics of propagation of premature impulses make more likely that S3 impulses block at sites of structural heterogeneities than S2 impulses block; (2) Structural heterogeneities causing an increase in λ (or CV) of >40% could result in block of premature impulses; (3) A decrease in the maximum slope of CV restitution curves of propagating premature impulses is indicative of an increased potential for block at structural heterogeneities.

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Arrhythmogenic role of the border between two areas of cardiac cell alignment

Cited by 10 publications

References 37 publications

Conditions for Waveblock Due to Anisotropy in a Model of Human Ventricular Tissue

Conditions for Waveblock Due to Anisotropy in a Model of Human Ventricular Tissue

Fast propagation regions cause self-sustained reentry in excitable media

Dynamics of propagation of premature impulses in structurally remodeled infarcted myocardium: a computational analysis

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