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monodomain model

Francisco Sahli Costabal, Junaid A B Zaman, Ellen Kuhl, Sanjiv M Narayan
Atrial fibrillation is the most common rhythm disorder of the heart associated with a rapid and irregular beating of the upper chambers. Activation mapping remains the gold standard to diagnose and interpret atrial fibrillation. However, fibrillatory activation maps are highly sensitive to far-field effects, and often disagree with other optical mapping modalities. Here we show that computational modeling can identify spurious non-local components of atrial fibrillation electrograms and improve activation mapping...
February 2018: Annals of Biomedical Engineering
Arno M Janssen, Danila Potyagaylo, Olaf Dössel, Thom F Oostendorp
Promising results have been reported in noninvasive estimation of cardiac activation times (AT) using the equivalent dipole layer (EDL) source model in combination with the boundary element method (BEM). However, the assumption of equal anisotropy ratios in the heart that underlies the EDL model does not reflect reality. In the present study, we quantify the errors of the nonlinear AT imaging based on the EDL approximation. Nine different excitation patterns (sinus rhythm and eight ectopic beats) were simulated with the monodomain model...
November 13, 2017: Medical & Biological Engineering & Computing
Cesare Corrado, Nejib Zemzemi
Computational models of heart electrophysiology achieved a considerable interest in the medical community as they represent a novel framework for the study of the mechanisms underpinning heart pathologies. The high demand of computational resources and the long computational time required to evaluate the model solution hamper the use of detailed computational models in clinical applications. In this paper, we present a multi-front eikonal algorithm that adapts the conduction velocity (CV) to the activation frequency of the tissue substrate...
January 2018: Medical Image Analysis
Simone Rossi, Boyce E Griffith
In standard models of cardiac electrophysiology, including the bidomain and monodomain models, local perturbations can propagate at infinite speed. We address this unrealistic property by developing a hyperbolic bidomain model that is based on a generalization of Ohm's law with a Cattaneo-type model for the fluxes. Further, we obtain a hyperbolic monodomain model in the case that the intracellular and extracellular conductivity tensors have the same anisotropy ratio. In one spatial dimension, the hyperbolic monodomain model is equivalent to a cable model that includes axial inductances, and the relaxation times of the Cattaneo fluxes are strictly related to these inductances...
September 2017: Chaos
P Colli Franzone, L F Pavarino, S Scacchi
In this work, we investigate the influence of cardiac tissue deformation on re-entrant wave dynamics. We have developed a 3D strongly coupled electro-mechanical Bidomain model posed on an ideal monoventricular geometry, including fiber direction anisotropy and stretch-activated currents (SACs). The cardiac mechanical deformation influences the bioelectrical activity with two main mechanical feedback: (a) the geometric feedback (GEF) due to the presence of the deformation gradient in the diffusion coefficients and in a convective term depending on the deformation rate and (b) the mechano-electric feedback (MEF) due to SACs...
September 2017: Chaos
Alessandro Barone, Flavio Fenton, Alessandro Veneziani
An accurate estimation of cardiac conductivities is critical in computational electro-cardiology, yet experimental results in the literature significantly disagree on the values and ratios between longitudinal and tangential coefficients. These are known to have a strong impact on the propagation of potential particularly during defibrillation shocks. Data assimilation is a procedure for merging experimental data and numerical simulations in a rigorous way. In particular, variational data assimilation relies on the least-square minimization of the misfit between simulations and experiments, constrained by the underlying mathematical model, which in this study is represented by the classical Bidomain system, or its common simplification given by the Monodomain problem...
September 2017: Chaos
Martín Fló, Mariana Margenat, Leonardo Pellizza, Martín Graña, Rosario Durán, Adriana Báez, Emilio Salceda, Enrique Soto, Beatriz Alvarez, Cecilia Fernández
We previously reported a multigene family of monodomain Kunitz proteins from Echinococcus granulosus (EgKU-1-EgKU-8), and provided evidence that some EgKUs are secreted by larval worms to the host interface. In addition, functional studies and homology modeling suggested that, similar to monodomain Kunitz families present in animal venoms, the E. granulosus family could include peptidase inhibitors as well as channel blockers. Using enzyme kinetics and whole-cell patch-clamp, we now demonstrate that the EgKUs are indeed functionally diverse...
February 2017: PLoS Pathogens
Benjamin L Schwartz, Munish Chauhan, Rosalind J Sadleir
Presented here is a model of neural tissue in a conductive medium stimulated by externally injected currents. The tissue is described as a conductively isotropic bidomain, i.e. comprised of intra and extracellular regions that occupy the same space, as well as the membrane that divides them, and the injection currents are described as a pair of source and sink points. The problem is solved in three spatial dimensions and defined in spherical coordinates [Formula: see text]. The system of coupled partial differential equations is solved by recasting the problem to be in terms of the membrane and a monodomain, interpreted as a weighted average of the intra and extracellular domains...
December 2016: Journal of Mathematical Neuroscience
Yu Xia, Elaine Lee, Hao Hu, Mohamed Amine Gharbi, Daniel A Beller, Eva-Kristina Fleischmann, Randall D Kamien, Rudolf Zentel, Shu Yang
Controlling the molecular alignment of liquid crystal monomers (LCMs) within nano- and microstructures is essential in manipulating the actuation behavior of nematic liquid crystal elastomers (NLCEs). Here, we study how to induce uniformly vertical alignment of nematic LCMs within a micropillar array to maximize the macroscopic shape change using surface chemistry. Landau-de Gennes numerical modeling suggests that it is difficult to perfectly align LCMs vertically in every pore within a poly(dimethylsiloxane) (PDMS) mold with porous channels during soft lithography...
May 18, 2016: ACS Applied Materials & Interfaces
Benjamin L Schwartz, Rosalind J Sadleir
The recently increasing role in medical imaging that electrophysiology plays has spurned the need for its quantitative analysis at all scales-ions, cells, tissues, organs, etc.; so, here is presented a model of nerve tissue in a spherical volume excited by a point current source at one pole and a point current sink at the opposite pole. The sphere of tissue is described as an isotropic bidomain, consisting of the intra- and extra-cellular regions and the membrane that separates them, and is immersed in an infinite isotropic conductive bath...
2015: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Nicole Cusimano, Alfonso Bueno-Orovio, Ian Turner, Kevin Burrage
Space-fractional operators have been used with success in a variety of practical applications to describe transport processes in media characterised by spatial connectivity properties and high structural heterogeneity altering the classical laws of diffusion. This study provides a systematic investigation of the spatio-temporal effects of a space-fractional model in cardiac electrophysiology. We consider a simplified model of electrical pulse propagation through cardiac tissue, namely the monodomain formulation of the Beeler-Reuter cell model on insulated tissue fibres, and obtain a space-fractional modification of the model by using the spectral definition of the one-dimensional continuous fractional Laplacian...
2015: PloS One
Gianmauro Cuccuru, Giorgio Fotia, Fabio Maggio, James Southern
We discuss the application of the spectral element method to the monodomain and bidomain equations describing propagation of cardiac action potential. Models of cardiac electrophysiology consist of a system of partial differential equations coupled with a system of ordinary differential equations representing cell membrane dynamics. The solution of these equations requires solving multiple length scales due to the ratio of advection to diffusion that varies among the different equations. High order approximation of spectral elements provides greater flexibility in resolving multiple length scales...
2015: BioMed Research International
Yong Xia, Kuanquan Wang, Henggui Zhang
Large-scale 3D virtual heart model simulations are highly demanding in computational resources. This imposes a big challenge to the traditional computation resources based on CPU environment, which already cannot meet the requirement of the whole computation demands or are not easily available due to expensive costs. GPU as a parallel computing environment therefore provides an alternative to solve the large-scale computational problems of whole heart modeling. In this study, using a 3D sheep atrial model as a test bed, we developed a GPU-based simulation algorithm to simulate the conduction of electrical excitation waves in the 3D atria...
2015: Computational and Mathematical Methods in Medicine
Qiaoxuan Zhang, Paul J Ackerman, Qingkun Liu, Ivan I Smalyukh
We experimentally realize polydomain and monodomain chiral ferromagnetic liquid crystal colloids that exhibit solitonic and knotted vector field configurations. Formed by dispersions of ferromagnetic nanoplatelets in chiral nematic liquid crystals, these colloidal ferromagnets exhibit spontaneous long-range alignment of magnetic dipole moments of individual platelets, giving rise to a continuum of the magnetization field M(r). Competing effects of surface confinement and chirality prompt spontaneous formation and enable the optical generation of localized twisted solitonic structures with double-twist tubes and torus knots of M(r), which exhibit a strong sensitivity to the direction of weak magnetic fields ∼1  mT...
August 28, 2015: Physical Review Letters
Wouter-Jan Rappel, Junaid A B Zaman, Sanjiv M Narayan
BACKGROUND: Human atrial fibrillation (AF) can terminate after ablating localized regions, which supports the existence of localized rotors (spiral waves) or focal drivers. However, it is unclear why ablation near a spiral wave tip would terminate AF and not anchor reentry. We addressed this question by analyzing competing mechanisms for AF termination in numeric simulations, referenced to clinical observations. METHODS AND RESULTS: Spiral wave reentry was simulated in monodomain 2-dimensional myocyte sheets using clinically realistic rate-dependent values for repolarization and conduction...
December 2015: Circulation. Arrhythmia and Electrophysiology
Kevin P Vincent, Matthew J Gonzales, Andrew K Gillette, Christopher T Villongco, Simone Pezzuto, Jeffrey H Omens, Michael J Holst, Andrew D McCulloch
Computational modeling of tissue-scale cardiac electrophysiology requires numerically converged solutions to avoid spurious artifacts. The steep gradients inherent to cardiac action potential propagation necessitate fine spatial scales and therefore a substantial computational burden. The use of high-order interpolation methods has previously been proposed for these simulations due to their theoretical convergence advantage. In this study, we compare the convergence behavior of linear Lagrange, cubic Hermite, and the newly proposed cubic Hermite-style serendipity interpolation methods for finite element simulations of the cardiac monodomain equation...
2015: Frontiers in Physiology
Martin A Rossotti, Andrés González-Techera, Julio Guarnaschelli, Lucia Yim, Ximena Camacho, Marcelo Fernández, Pablo Cabral, Carmen Leizagoyen, José A Chabalgoity, Gualberto González-Sapienza
Recombinant single domain antibodies (nanobodies) constitute an attractive alternative for the production of neutralizing therapeutic agents. Their small size warrants rapid bioavailability and fast penetration to sites of toxin uptake, but also rapid renal clearance, which negatively affects their performance. In this work, we present a new strategy to drastically improve the neutralizing potency of single domain antibodies based on their fusion to a second nanobody specific for the complement receptor CD11b/CD18 (Mac-1)...
2015: MAbs
Vincent Jacquemet
This paper presents the mathematical formulation, the numerical validation and several illustrations of a forward-modeling approach based on dipole-current sources to compute the contribution of a part of the heart to the electrocardiogram (ECG). Clinically relevant applications include identifying in the ECG the contributions from the right and the left atrium. In a Courtemanche-based monodomain computer model of the atria and torso, 1000 dipoles distributed throughout the atrial mid-myocardium are found to be sufficient to reproduce body surface potential maps with a relative error <1% during both sinus rhythm and atrial fibrillation...
October 1, 2015: Computers in Biology and Medicine
Ernesto Pérez-Rueda, Silvia Tenorio-Salgado, Alejandro Huerta-Saquero, Yalbi I Balderas-Martínez, Gabriel Moreno-Hagelsieb
Motivated by the experimental evidences accumulated in the last ten years and based on information deposited in RegulonDB, literature look up, and sequence analysis, we analyze the repertoire of 304 DNA-binding Transcription factors (TFs) in Escherichia coli K-12. These regulators were grouped in 78 evolutionary families and are regulating almost half of the total genes in this bacterium. In structural terms, 60% of TFs are composed by two-domains, 30% are monodomain, and 10% three- and four-structural domains...
October 2015: Computational Biology and Chemistry
Yves Coudière, Jacques Henry, Simon Labarthe
Numerical simulations of the cardiac electrophysiology in the atria are often based on the standard bidomain or monodomain equations stated on a two-dimensional manifold. These simulations take advantage of the thinness of the atrial tissue, and their computational cost is reduced, as compared to three-dimensional simulations. However, these models do not take into account the heterogeneities located in the thickness of the tissue, like discontinuities of the fiber direction, although they can be a substrate for atrial arrhythmia (Hocini et al...
December 2015: Journal of Mathematical Biology
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