The role of extracellular potassium transport in computer models of the ischemic zone

Abstract

Ischemic heart disease is associated with large mortality and morbidity. Understanding of the relations between coronary artery occlusion, geometry of the ischemic region, physiology of ischemia, and the resulting changes in electrocardiogram (ECG) leads and catheter signals is important to support diagnosis and treatment. Computer models play an important role in understanding ischemia, by linking experimental to clinical results. In this paper we argue that the observed transport of extracellular potassium should be represented in such models. We used a diffusion equation to describe the transport mechanism. This model reproduced the measured spatial distribution of potassium, and its temporal development. We discuss the role of potassium transport next to other aspects of ischemia: the mechanism of changes in action potential and ECG, cellular coupling, anisotropic bidomain tissue conductivity, and the geometry of the ischemic zone.

Multiscale computational analysis of the bioelectric consequences of myocardial ischaemia and infarction

“…Potse et al used a one-dimensional (1D) diffusive model for K + ions to establish the spatial profile of [K + ] o across the BZ. 69 The results predict a non-linear [K + ] o spatial evolution within the BZ, showing a steep rise in the BZ adjacent to the NZ and a more flattened behaviour near the CIZ. The authors demonstrate that the diffusion constant which would be needed to explain the experimentally observed profile of K + in the BZ is too large, suggesting that physical diffusion is not the only 5 mechanism that plays a role in the establishment of the BZ.…”

Regulation of Ion Gradients across Myocardial Ischemic Border Zones: A Biophysical Modelling Analysis

“…The limited attempts at simulating the spatial temporal evolution of ionic gradients across the ischemic BZ have largely uncoupled the movement of ions and the electric field. Potse et al, [18] demonstrated that measured gradients across an ischemic BZ could be simulated using a model of diffusion coupled to a source term. The spatially varying gradient could then be included as a boundary condition to models of transmembrane current in the bidomain equations.…”

“…Previous models of electrophysiology during acute regional ischemia have simulated the effects of these spatial gradients but have not simulated their time evolution [15]–[17]. More recent work has simulated the time evolution of gradients [18], but have not considered other ionic gradients, the effects of nonlinear interactions between and other ions, the effect of diffusion in the intracellular space or the effects of potential gradients on ion diffusion.…”

Approche multi-échelle appliqué à la modélisation de l’activité électrique du coeur

“…Cependant, certains problèmes ne peuvent être abordés qu'avec un modèle qui représente les flux ioniques provenant des myocytes et qui incorpore leurs interactions avec les flux circulant dans le milieu extracellulaire cardiaque et dans le torse. Cela est vrai pour les maladies affectant les canaux ioniques ou pour comprendre la genèse d'arythmies survenant en bordure d'une région ischémique où l'absence de perfusion altère la composition ionique des milieux intra et extracellulaires et l'état des myocytes [22]. Actuellement, seules de petites préparations permettent de représenter tous les myocytes et la microstructure du tissu cardiaque.…”