Nonlinear and stochastic dynamics in the heart

Qu, Zhilin; Hu, Gang; Garfinkel, Alan; Weiss, James N.

doi:10.1016/j.physrep.2014.05.002

Cited by 187 publications

(147 citation statements)

References 570 publications

(838 reference statements)

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“…This aspect was recently covered by a longer review article [27]. Often these models describe the fluctuation at the level of a single cell.…”

Section: Discussion and Outlookmentioning

confidence: 99%

“…For more information on these topics see, e.g., the excellent reviews by Falcke [26] for a general discussion of intercellular calcium handling and by Qu and colleagues [27] for a description of recent progress on stochastic calcium dynamics in cardiac cells. Recently, many efforts have been undertaken to employ information on cardiac anatomy and geometry from MRI imaging, histology and other experimental techniques in order to built realistic models of three dimensional propagation.…”

Section: Introductionmentioning

confidence: 99%

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Nonlinear physics of electrical wave propagation in the heart: a review

2016

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Abstract. The beating of the heart is a synchronized contraction of muscle cells (myocytes) that are triggered by a periodic sequence of electrical waves (action potentials) originating in the sino-atrial node and propagating over the atria and the ventricles. Cardiac arrhythmias like atrial and ventricular fibrillation (AF,VF) or ventricular tachycardia (VT) are caused by disruptions and instabilities of these electrical excitations, that lead to the emergence of rotating waves (VT) and turbulent wave patterns (AF,VF). Numerous simulation and experimental studies during the last 20 years have addressed these topics. In this review we focus on the nonlinear dynamics of wave propagation in the heart with an emphasis on the theory of pulses, spirals and scroll waves and their instabilities in excitable media and their application to cardiac modeling. After an introduction into electrophysiological models for action potential propagation, the modeling and analysis of spatiotemporal alternans, spiral and scroll meandering, spiral breakup and scroll wave instabilities like negative line tension and sproing are reviewed in depth and discussed with emphasis on their impact in cardiac arrhythmias.

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“…This aspect was recently covered by a longer review article [27]. Often these models describe the fluctuation at the level of a single cell.…”

Section: Discussion and Outlookmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nonlinear physics of electrical wave propagation in the heart: a review

2016

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“…abnormal or irregular heart rhythms) including atrial fibrillation (AF), ventricular fibrillation (VF), and ventricular tachycardia (VT). The nonlinear dynamics of electrical excitation waves in cardiac tissue has been studied extensively in experiment and simulation for more than two decades, for recent reviews see e. g. [1][2][3][4][5] . VF represents a particularly dangerous malfunction of the heart, in which synchronous excitation and contraction of different parts of the ventricles is lost, potentially causing sudden death if left untreated for more than a few minutes.…”

Section: Introductionmentioning

confidence: 99%

Control of electrical turbulence by periodic excitation of cardiac tissue

Buran

Bär

Alonso

et al. 2017

Chaos: An Interdisciplinary Journal of Nonlinear Science

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Electrical turbulence in cardiac tissue is associated with arrhythmias such as the life-threatening ventricular fibrillation. The application of a high-energy electrical shock constitutes an effective defibrillation, but also causes severe side effects. Recent experimental studies have shown that a sequence of low energy electrical far-field pulses is able to terminate fibrillation more gently than a single pulse. During this low-energy antifibrillation pacing (LEAP) only tissue near sufficiently large conduction heterogeneities, such as large coronary arteries, is activated. In order to understand and potentially optimize LEAP, we performed extensive simulations of cardiac tissue perforated by blood vessels. We checked three alternative cellular models that exhibit qualitatively different electrical turbulence. LEAP may operate if and only if the spectrum of this chaotic activity is characterized by a narrow peak around a dominant frequency. For each of 100 initial conditions, we tested different electrical field strengths, pulse shapes, numbers of pulses, and periods between the pulses. It turned out that the optimal period matches the dominant period of the chaotic activity while both over-and underdrive pacing lead to a considerably smaller success probability and higher field strength for reliable defibrillation. An optimal LEAP protocol, which minimizes the required total energy for successful defibrillation, consists of five or six pulses. Compared to a single bi-phasic defibrillation pulse, it reduces the total energy by about 86%, corresponding to an energy reduction of 97 -98% per pulse.PACS numbers: ... Keywords: cardiac modeling, excitable media, defibrillation, low-energy antifibrillation pacing (LEAP)In ventricular fibrillation, the heart is quivering instead of pumping, a condition which leads to cardiac arrest and ultimately to death. This loss of synchronous contraction stems from disorganized electrical activity in the ventricles. Emergency defibrillation is achieved by the application of a strong electrical shock which is accompanied by severe side effects such as tissue damage and trauma. Recently, an alternative treatment using a sequence of low energy pulses has been suggested in which each electrical pulse excites only localized tissue sites at the large heterogeneities -such as blood vessels -instead of the entire tissue. In laboratory experiments in vitro and in vivo, this so-called low-energy antifibrillation pacing (LEAP) with five pulses achieves defibrillation with an energy reduction of 80 -90 % per pulse in comparison with standard single shock treatment. Here, we perform an extensive numerical study of LEAP employing far field pacing at the major blood vessels. We have tested three alternative electrophysiological models that exhibit qualitatively different spatiotemporally chaotic activity. LEAP operates if and only if the spectrum of this chaotic activity is characterized by a narrow peak around a dominant frequency. In this case, a resonant pacing with the same frequency and a ...

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“…This is because membrane voltage is strongly affected by Ca-sensitive ionic currents, and, conversely, cellular Ca loading is strongly influenced by voltage-dependent ionic currents, referred to as bidirectional Ca-voltage coupling. Ca-voltage coupling can promote complex AP dynamics in the heart (9). Analyzing the interactions between EADs and DADs (and voltage and Ca-cycling coupling dynamics in general), however, has been challenging, because the Ca cycling dynamics (e.g., Ca waves and oscillations) result from a spatially distributed heterogeneous network of Ca release units (CRUs) in the cell.…”

Section: Introductionmentioning

confidence: 99%

Calcium-Voltage Coupling in the Genesis of Early and Delayed Afterdepolarizations in Cardiac Myocytes

Song

Nivala

et al. 2015

Biophysical Journal

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Early afterdepolarizations (EADs) and delayed afterdepolarizations (DADs) are voltage oscillations known to cause cardiac arrhythmias. EADs are mainly driven by voltage oscillations in the repolarizing phase of the action potential (AP), while DADs are driven by spontaneous calcium (Ca) release during diastole. Because voltage and Ca are bidirectionally coupled, they modulate each other's behaviors, and new AP and Ca cycling dynamics can emerge from this coupling. In this study, we performed computer simulations using an AP model with detailed spatiotemporal Ca cycling incorporating stochastic openings of Ca channels and ryanodine receptors to investigate the effects of Ca-voltage coupling on EAD and DAD dynamics. Simulations were complemented by experiments in mouse ventricular myocytes. We show that: 1) alteration of the Ca transient due to increased ryanodine receptor leakiness and/or sarco/endoplasmic reticulum Ca ATPase activity can either promote or suppress EADs due to the complex effects of Ca on ionic current properties; 2) spontaneous Ca waves also exhibit complex effects on EADs, but cannot induce EADs of significant amplitude without the participation of I Ca,L ; 3) lengthening AP duration and the occurrence of EADs promote DADs by increasing intracellular Ca loading, and two mechanisms of DADs are identified, i.e., Ca-wave-dependent and Ca-wave-independent; and 4) Ca-voltage coupling promotes complex EAD patterns such as EAD alternans that are not observed for solely voltage-driven EADs. In conclusion, Ca-voltage coupling combined with the nonlinear dynamical behaviors of voltage and Ca cycling play a key role in generating complex EAD and DAD dynamics observed experimentally in cardiac myocytes, whose mechanisms are complex but analyzable.

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Nonlinear and stochastic dynamics in the heart

Cited by 187 publications

References 570 publications

Nonlinear physics of electrical wave propagation in the heart: a review

Nonlinear physics of electrical wave propagation in the heart: a review

Control of electrical turbulence by periodic excitation of cardiac tissue

Calcium-Voltage Coupling in the Genesis of Early and Delayed Afterdepolarizations in Cardiac Myocytes

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