Computerized Modeling of Electrophysiology and Pathoelectrophysiology of the Atria -- How Much Detail is Needed?

TL;DR

This review examines how much anatomical, cellular, and tissue-detail is needed to reliably simulate atrial electrophysiology and pathoelectrophysiology for planning ablation. It integrates cellular remodeling, atrial geometry, fiber orientation, anisotropy, and fibrosis into a spectrum of propagation models from bidomain to eikonal, emphasizing the trade-off between accuracy and computational efficiency. The authors advocate personalized, 3D or bilayer atrial models with realistic remodeling and ERP properties, combined with extended eikonal approaches to enable fast yet trustworthy simulations, and they call for robust validation against measured EGMs/ECGs. They also discuss cohort modeling and ablation strategy testing, highlighting the need for experimental data, standardization, and clinical validation to translate simulations into improved patient outcomes.

Abstract

This review focuses on the computerized modeling of the electrophysiology of the human atria, emphasizing the simulation of common arrhythmias such as atrial flutter (AFlut) and atrial fibrillation (AFib). Which components of the model are necessary to accurately model arrhythmogenic tissue modifications, including remodeling, cardiomyopathy, and fibrosis, to ensure reliable simulations? The central question explored is the level of detail required for trustworthy simulations for a specific context of use. The review discusses the balance between model complexity and computational efficiency, highlighting the risks of oversimplification and excessive detail. It covers various aspects of atrial modeling, from cellular to whole atria levels, including the influence of atrial geometry, fiber direction, anisotropy, and wall thickness on simulation outcomes. The article also examines the impact of different modeling approaches, such as volumetric 3D models, bilayer models, and single surface models, on the realism of simulations. In addition, it reviews the latest advances in the modeling of fibrotic tissue and the verification and validation of atrial models. The intended use of these models in planning and optimization of atrial ablation strategies is discussed, with a focus on personalized modeling for individual patients and cohort-based approaches for broader applications. The review concludes by emphasizing the importance of integrating experimental data and clinical validation to enhance the utility of computerized atrial models to improve patient outcomes.

Figures (5)

• Figure 1: Aspects of computerized modeling of electrophysiology and pathoelectrophysiology of the atria with planning of successful ablation as the intended use.
• Figure 2: A combined clinical and simulation study of electrograms during AFib. For details, see text. Reproduced from Jadidi et al. Jadidi-2020-ID14174 under a Creative Commons Attribution 4.0 International License.
• Figure 3: Quantitative determination of vulnerability using various methods. For details, see text. Reproduced from Azzolin et al. Azzolin-2021-ID16137 under a Creative Commons Attribution 4.0 International License.
• Figure 4: Differences in atrial substrate using late gadolinium enhancement-magnetic resonance imaging, electrogram voltage, and conduction velocity. Reproduced from Nairn et al. Nairn-2023-ID18842 under a Creative Commons Attribution 4.0 International License.
• Figure 5: Non-Invasive and quantitative estimation of left atrial fibrosis based on P-waves of the 12-Lead ECG. Reproduced from Nagel et al. Nagel-2021-ID16114 under a Creative Commons Attribution 4.0 International License.