Defining myocardial fiber bundle architecture in atrial digital twins

Area of Science:

• Biomedical Engineering
• Computational Biology
• Medical Imaging

Background:

• Accurate myocardial fiber orientation is crucial for patient-specific atrial digital twins (ADT).
• Current methods for generating atrial fibers in ADT often rely on mathematical models that lack validation and are limited by specific atrial morphologies.
• Reconstructing atrial fibers directly from medical imaging presents significant challenges.

Purpose of the Study:

• To introduce a novel, robust method for prescribing detailed myofiber orientations and regional annotation in complex bi-atrial geometries for ADT.
• To validate the proposed method against high-resolution Diffusion-Tensor-Magnetic-Resonance Imaging (DTMRI) data.
• To compare the performance of the novel method with existing state-of-the-art fiber models in electrophysiology simulations.

Main Methods:

• Development of the atrial Laplace-Dirichlet-Rule-Based Method (LDRBM) for generating myofiber orientations.
• Validation using eight detailed bi-atrial geometries derived from sub-millimeter DTMRI human atrial fiber datasets.
• Quantitative comparison of LDRBM-generated fibers with DTMRI ground truth and assessment of resulting electrophysiology simulation differences.

Main Results:

• The LDRBM successfully recreated DTMRI fiber architectures with high fidelity across diverse and complex bi-atrial morphologies.
• Electrophysiology simulations using LDRBM-prescribed fibers showed improved accuracy compared to simulations using other models.
• The LDRBM demonstrated superior performance over existing methods, including Universal Atrial Coordinates.

Conclusions:

• The LDRBM provides a robust and accurate method for prescribing detailed myofiber orientations in ADT, outperforming current state-of-the-art approaches.
• Accurate fiber orientation prescription is critical for reliable electrophysiology simulations within ADT.
• This work establishes a new standard for fiber modeling in ADT, paving the way for advanced physics-based digital twins of the human atria.