Representing Cardiac Bidomain Bath-Loading Effects by an Augmented Monodomain Approach: Application to Complex Ventricular Models

Abstract

Although the cardiac bidomain model has been widely used in the simulation of electrical activation, its relatively computationally expensive nature means that monodomain approaches are generally required for long duration simulations (for example, investigations of arrhythmia mechanisms). However, the presence of a conducting bath surrounding the tissue is known to induce wavefront curvature (surface leading bulk), a phenomena absent in standard monodomain approaches. Here, we investigate the biophysical origin of the bidomain bath-loading induced wavefront curvature and present a novel augmented monodomain equivalent bidomain approach faithfully replicating all aspects of bidomain wavefront morphology and conduction velocity, but with a fraction of the computational cost. Bath-loading effects are shown to be highly dependent upon specific conductivity parameters, but less dependent upon the thickness or conductivity of the surrounding bath, with even relatively thin surrounding fluid layers (~ 0.1 mm) producing significant wavefront curvature in bidomain simulations. We demonstrate that our augmented monodomain approach can be easily adapted for different conductivity sets and applied to anatomically complex models thus facilitating fast and accurate simulation of cardiac wavefront dynamics during long duration simulations, further aiding the faithful comparison of simulations with experiments.

Subepicardial Action Potential Characteristics Are a Function of Depth and Activation Sequence in Isolated Rabbit Hearts

“…28 In line with previous studies, 7,29 TRise during transverse propagation is faster than longitudinal propagation close to the tissue surface but this diminishes with increasing tissue depth, reflecting the reduced influence of bathloading deeper into the myocardium. Removal of the bath component abolishes this behavior ( Figure 4B).…”

Microscopic Isthmuses and Fibrosis Within the Border Zone of Infarcted Hearts Promote Calcium-Mediated Ectopy and Conduction Block

“…where σ m = diag(σ ml , σ mt , σ mt ) is the harmonic mean conductivity tensor or the effective bulk conductivity [34]; V m is the transmembrane voltage; β is the surface to volume ratio; I m is the transmembrane current density; C m is the membrane capacitance per unit area; I ion is the density of the total ionic current flowing through the membrane channels, pumps and exchangers; and I stim is the stimulus current density. I ion depends on V m as well as on a set of state variables η which describes channel gating and ionic concentrations according to the vectorvalued function f (V m , η).…”

A Coupled Model for the Left Ventricle Including Regional Differences in Structure

“…The passive mechanical response of myocardium is, therefore, modeled as an orthotropic material with a hyperelastic stress response [1][2][3], and the active response is also regulated by these directions in terms of the conduction speed [4,5]. The main focus in this communication is to highlight the difference when using two different setups of fiber and sheet orientations, i.e.…”