Modeling cardiac muscle fibers in ventricular and atrial electrophysiology simulations

TL;DR

This paper introduces a unified framework based on Laplace-Dirichlet rule-based methods for generating cardiac muscle fibers in heart electrophysiology simulations, including a novel method for atrial fibers and comprehensive validation.

Contribution

The work provides a systematic comparison of existing ventricular LDRBMs, introduces a new LDRBM for atrial fibers applicable to arbitrary geometries, and demonstrates their use in realistic whole heart models.

Findings

Systematic comparison of ventricular LDRBMs using biomarkers

First LDRBM for atrial fiber generation

Successful application in realistic whole heart models

Abstract

Since myocardial fibers drive the electric signal propagation throughout the myocardium, accurately modeling their arrangement is essential for simulating heart electrophysiology (EP). Rule-Based-Methods (RBMs) represent a commonly used strategy to include cardiac fibers in computational models. A particular class of such methods is known as Laplace-Dirichlet-Rule-Based-Methods (LDRBMs) since they rely on the solution of Laplace problems. In this work we provide a unified framework, based on LDRBMs, for generating full heart muscle fibers. First, we review existing ventricular LDRBMs providing a communal mathematical description and introducing also some modeling improvements with respect to the existing literature. We then carry out a systematic comparison of LDRBMs based on meaningful biomarkers produced by numerical EP simulations. Next we propose, for the first time, a LDRBM to be used for generating atrial fibers. The new method, tested both on idealized and realistic atrial models, can be applied to any arbitrary geometries. Finally, we present numerical results obtained in a realistic whole heart where fibers are included for all the four chambers using the discussed LDRBMs.