Editor’s Perspective: The Isthmus of Uncertainty

Asirvatham, Samuel J.; Stevenson, William G.

doi:10.1161/circep.114.001425

Cited by 6 publications

(6 citation statements)

References 9 publications

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“…Consisting of non-conductive collagenous regions occurring in a variety of patterns of deposition, cardiac fibrosis is challenging to represent using upscaled tensors. For example, isthmuses through regions of scarring are of particular interest as potential substrates for arrhythmia [48] , here represented on the fine scale by a thin channel(s) of conductive material passing through an otherwise non-conductive domain. However, where the ends of such channels do not align with each other at the edges of the upscaled element, the periodic assumptions underlying homogenisation then incorrectly imply a non-conductive structure [11] (see also Fig.…”

Section: Resultsmentioning

confidence: 99%

Homogenisation for the monodomain model in the presence of microscopic fibrotic structures

Lawson

Santos

Turner

et al. 2023

Communications in Nonlinear Science and Numerical Simulation

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Section: Resultsmentioning

confidence: 99%

Homogenisation for the monodomain model in the presence of microscopic fibrotic structures

Lawson

Santos

Turner

et al. 2023

Communications in Nonlinear Science and Numerical Simulation

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“…In particular, this assumption will not function when conduction takes place through thin channels stretching across different averaging volumes, as unless those channels happen to align at the opposite ends of an individual volume, the periodic extension implies a non-conducting structure [10]. This scenario arises in the cardiac electrophysiology context through conductive isthmuses (channels) running through non-conductive scar regions, which are of particular interest as potential substrates for arrhythmia [32].…”

Section: Closure Problem Boundary Conditionsmentioning

confidence: 99%

Homogenisation for the monodomain model in the presence of microscopic fibrotic structures

Lawson¹,

Santos²,

Turner³

et al. 2020

Preprint

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Computational models in cardiac electrophysiology are notorious for long runtimes, restricting the numbers of nodes and mesh elements in the numerical discretisations used for their solution. This makes it particularly challenging to incorporate structural heterogeneities on small spatial scales, preventing a full understanding of the critical arrhythmogenic effects of conditions such as cardiac fibrosis. In this work, we explore the technique of homogenisation by volume averaging for the inclusion of non-conductive micro-structures into larger-scale cardiac meshes with minor computational overhead. Importantly, our approach is not restricted to periodic patterns, enabling homogenised models to represent, for example, the intricate patterns of collagen deposition present in different types of fibrosis. We first highlight the importance of appropriate boundary condition choice for the closure problems that define the parameters of homogenised models. Then, we demonstrate the technique's ability to correctly upscale the effects of fibrotic patterns with a spatial resolution of 10 µm into much larger numerical mesh sizes of 100-250 µm. The homogenised models using these coarser meshes correctly predict critical pro-arrhythmic effects of fibrosis, including slowed conduction, source/sink mismatch, and stabilisation of re-entrant activation patterns. As such, this approach to homogenisation represents a significant step towards whole organ simulations that unravel the effects of microscopic cardiac tissue heterogeneities.

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“…Indeed, even with circumferential isolation of the LIPV, conduction may proceed through another posterior vein or between veins. This fundamental lack of a posterior boundary in the LA, unless artificially created with ablation, causes significant difficulty both with eliminating perimitral flutter and when trying to ascertain whether or not bidirectional block is present …”

Section: Introductionmentioning

confidence: 99%