Mechanisms of target and spiral wave propagation in single cells

1994 ◽  
Vol 4 (3) ◽  
pp. 473-476 ◽  
Author(s):  
A. Babloyantz
Keyword(s):  
Wave Propagation ◽  
Single Cells ◽  
Spiral Wave

scholarly journals Arrhythmia Mechanisms and Spontaneous Calcium Release: II - From Calcium Spark to Re-entry and Back

2018 ◽  
Author(s):  
Michael A. Colman
Keyword(s):  
Calcium Release ◽  
Single Cells ◽  
Computational Cost ◽  
Conduction Block ◽  
Spiral Wave ◽  
Positive Role ◽  
Pharmacological Management ◽  
Calcium Dependent ◽  
Tissue Models

AbstractMotivationThe role of sub-cellular spontaneous calcium release events (SCRE) in the development of arrhythmia associated with atrial and ventricular tachycardia and fibrillation has yet to be investigated in detail. SCRE may underlie the emergence of spontaneous excitation in single cells, resulting in arrhythmic triggers in tissue. Furthermore, they can promote the substrate for conduction abnormalities. However, the potential interactions with re-entrant excitation have yet to be explored. The primary aim of this study was therefore to apply a novel computational approach to understand the multi-scale coupling between re-entrant excitation and SCRE.MethodsA general implementation of Spontaneous Release Functions - which reproduce the calcium dependent SCRE dynamics of detailed cell models at a significantly reduced computational cost - was used to reproduce SCRE in tissue models. Arrhythmic dynamics, such as rapid pacing and re-entry, were induced in the tissue models and the resulting interactions with SCRE were analysed.ResultsIn homogeneous tissue, the emergence of a spontaneous beat from a single source was observed and the positive role of coupling was demonstrated. Conduction block could be promoted by SCRE by both inactivation of the fast sodium channel as well as focal pacing heterogeneity interactions. Sustained re-entrant excitation promoted calcium overload, and led to the emergence of focal excitations both after termination of re-entry and also during re-entrant excitation. These results demonstrated a purely functional mechanism of re-entry and focal activity localisation, related to the unexcited spiral wave core.ConclusionsSCRE may interact with tissue excitation to promote and perpetuate arrhythmia through multiple mechanisms, including functional localisation and mechanism switching. These insights may be particularly relevant for successful pharmacological management of arrhythmia.

scholarly journals Spiral Wave Propagation in Communities with Spatially Correlated Heterogeneity

2020 ◽  
Vol 118 (7) ◽  
pp. 1721-1732 ◽  
Author(s):  
Xiaoling Zhai ◽  
Joseph W. Larkin ◽  
Gürol M. Süel ◽  
Andrew Mugler
Keyword(s):  
Wave Propagation ◽  
Spiral Wave ◽  
Spatially Correlated

scholarly journals Viscoelasticity Imaging of Biological Tissues and Single Cells Using Shear Wave Propagation

2021 ◽  
Vol 9 ◽  
Author(s):  
Hongliang Li ◽  
Guillaume Flé ◽  
Manish Bhatt ◽  
Zhen Qu ◽  
Sajad Ghazavi ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Shear Wave ◽  
Soft Tissues ◽  
Acoustic Radiation ◽  
Single Cells ◽  
Shear Waves ◽  
Mechanical Vibration ◽  
Shear Wave Elastography ◽  
Biomechanical Properties ◽  
Biological Tissues

Changes in biomechanical properties of biological soft tissues are often associated with physiological dysfunctions. Since biological soft tissues are hydrated, viscoelasticity is likely suitable to represent its solid-like behavior using elasticity and fluid-like behavior using viscosity. Shear wave elastography is a non-invasive imaging technology invented for clinical applications that has shown promise to characterize various tissue viscoelasticity. It is based on measuring and analyzing velocities and attenuations of propagated shear waves. In this review, principles and technical developments of shear wave elastography for viscoelasticity characterization from organ to cellular levels are presented, and different imaging modalities used to track shear wave propagation are described. At a macroscopic scale, techniques for inducing shear waves using an external mechanical vibration, an acoustic radiation pressure or a Lorentz force are reviewed along with imaging approaches proposed to track shear wave propagation, namely ultrasound, magnetic resonance, optical, and photoacoustic means. Then, approaches for theoretical modeling and tracking of shear waves are detailed. Following it, some examples of applications to characterize the viscoelasticity of various organs are given. At a microscopic scale, a novel cellular shear wave elastography method using an external vibration and optical microscopy is illustrated. Finally, current limitations and future directions in shear wave elastography are presented.

A tale of two dogs: analyzing two models of canine ventricular electrophysiology

2007 ◽  
Vol 292 (1) ◽  
pp. H43-H55 ◽  
Author(s):  
Elizabeth M. Cherry ◽  
Flavio H. Fenton
Keyword(s):  
Action Potential ◽  
Mathematical Models ◽  
Cardiac Electrophysiology ◽  
Animal Species ◽  
Cardiac Myocyte ◽  
Ventricular Myocytes ◽  
Single Cells ◽  
Spiral Wave ◽  
Canine Models ◽  
Transmembrane Currents

The extensive development of detailed mathematical models of cardiac myocyte electrophysiology in recent years has led to a proliferation of models, including many that model the same animal species and specific region of the heart and thus would be expected to have similar properties. In this paper we review and compare two recently developed mathematical models of the electrophysiology of canine ventricular myocytes. To clarify their similarities and differences, we also present studies using them in a range of preparations from single cells to two-dimensional tissue. The models are compared with each other and with new and previously published experimental results in terms of a number of their properties, including action potential morphologies; transmembrane currents during normal heart rates and during alternans; alternans onsets, magnitudes, and cessations; and reentry dynamics of spiral waves. Action potential applets and spiral wave movies for the two canine ventricular models are available online as supplemental material. We find a number of differences between the models, including their rate dependence, alternans dynamics, and reentry stability, and a number of differences compared with experiments. Differences between models of the same species and region of the heart are not unique to these canine models. Similar differences can be found in the behavior of two models of human ventricular myocytes and of human atrial myocytes. We provide several possible explanations for the differences observed in models of the same species and region of the heart and discuss the implications for the applicability of models in addressing questions of mechanism in cardiac electrophysiology.

Wave propagation and spiral wave formation in a Hindmarsh–Rose neuron model with fractional-order threshold memristor synaps

2020 ◽  
Vol 34 (17) ◽  
pp. 2050157 ◽  
Author(s):  
Karthikeyan Rajagopal ◽  
Anitha Karthikeyan ◽  
Sajad Jafari ◽  
Fatemeh Parastesh ◽  
Christos Volos ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Fractional Order ◽  
Electromagnetic Induction ◽  
Neuron Model ◽  
Spiral Wave ◽  
Spiral Waves ◽  
Bifurcation Diagrams ◽  
External Current ◽  
Proposed Model ◽  
External Stimuli

In this paper, a modified Hindmarsh–Rose neuron model is presented, which has a fractional-order threshold magnetic flux. The dynamics of the model is investigated by bifurcation diagrams and Lyapunov exponents in two cases of presence and absence of the external electromagnetic induction. Then the emergence of the spiral waves in the network of the proposed model is studied. To find the effects of different factors on the formation and destruction of spiral waves, the external current, the coupling strength and the external stimuli amplitude are varied. It is observed that all of these parameters have significant impacts on the spiral waves. Furthermore, the external electromagnetic induction influences the existence of spiral waves in specific external current values.

Why Is Only Type 1 Electrocardiogram Diagnostic of Brugada Syndrome? Mechanistic Insights From Computer Modeling

2021 ◽  
Author(s):  
Zhaoyang Zhang ◽  
Peng-Sheng Chen ◽  
James N. Weiss ◽  
Zhilin Qu
Keyword(s):  
Brugada Syndrome ◽  
Potassium Current ◽  
Sodium Current ◽  
Single Cells ◽  
Spiral Wave ◽  
Potassium Currents ◽  
Delayed Rectifier ◽  
Late Sodium Current

Background: Three types of characteristic ST-segment elevation are associated with Brugada syndrome but only type 1 is diagnostic. Why only type 1 ECG is diagnostic remains unanswered. Methods: Computer simulations were performed in single cells, 1-dimensional cables, and 2-dimensional tissues to investigate the effects of the peak and late components of the transient outward potassium current (I to ), sodium current, and L-type calcium current (I Ca,L ) as well as other potassium currents on the genesis of ECG morphologies and phase 2 reentry (P2R). Results: Although a sufficiently large peak I to was required to result in the type 1 ECG pattern and P2R, increasing the late component of I to converted type 1 ECG to type 2 ECG and suppressed P2R. Increasing the peak I to promoted spiral wave breakup, potentiating the transition from tachycardia to fibrillation, but increasing the late I to prevented spiral wave breakup by flattening the action potential duration restitution and preventing P2R. A sufficiently large I Ca,L conductance was needed for P2R to occur, but once above the critical conductance, blocking I Ca,L promoted P2R. However, selectively blocking the window and late components of I Ca,L suppressed P2R, countering the effect of the late I to . Blocking either the peak or late components of sodium current promoted P2R, with the late sodium current blockade having the larger effect. As expected, increasing other potassium currents potentiated P2R, with ATP-sensitive potassium current exhibiting a larger effect than rapid and slow component of the delayed rectifier potassium current. Conclusions: The peak I to promotes type 1 ECG and P2R, whereas the late I to converts type 1 ECG to type 2 ECG and suppresses P2R. Blocking the peak I Ca,L and either the peak or the late sodium current promotes P2R, whereas blocking the window and late I Ca,L suppresses P2R. These results provide important insights into the mechanisms of arrhythmogenesis and potential therapeutic targets for treatment of Brugada syndrome.

Control of Longitudinal Wave Propagation in Conical Periodic Structures

2004 ◽  
Vol 10 (12) ◽  
pp. 1795-1811 ◽  
Author(s):  
T. N. Tongele ◽  
T. Chen
Keyword(s):  
Wave Propagation ◽  
Longitudinal Wave ◽  
Periodic Structure ◽  
Periodic Structures ◽  
Single Cells ◽  
Frequency Bands ◽  
Active Devices ◽  
Theoretical Predictions ◽  
Longitudinal Wave Propagation ◽  
Specific Frequency

Conical periodic structure with single cells and multiple subcells is used to control longitudinal wave motion. It is well known that periodic structures by nature act as mechanical filters, allowing waves to propagate within specific frequency bands called pass bands, and blocking wave propagation within other frequency bands called stop bands. However, the conical geometry of cells and the use of conical subcells provide a conical periodic structure with the possibility of adjusting its impedance mismatch without the use of conventional active devices such as electromechanical, electrohydraulic, or piezoelectric actuators. The behavior of such a conical periodic structure is evaluated using single cells and cells with two, three, and four subcells. Theoretical predictions obtained by means of finite element modeling are compared with experimental results. Both experimental and theoretical results have converged in pointing to the effectiveness and the potential of using conical cells, and the concept of cells with subcells as tools for controlling longitudinal wave propagation in a periodic structure.

Sign in / Sign up

Export Citation Format

Share Document