Hemodynamic Impact of Geometrical and Structural Heterogeneity using Left Atrial Digital Twins

We recently developed a left atrial digital twinning (LADT) framework for patient-specific multiscale modeling of left atrial (LA) myocardial mechanics and blood flow [1]. In this work, we will enhance this modeling workflow to personalize myocardial excitation by coupling it with a biophysically detailed model of LA excitation-contraction, and incorporate variable wall thickness and material parameters to investigate the sensitivities of LA geometric and material heterogeneity on local hemodynamics. Patient-specific models of LA lumen and myocardium with uniform and variable thickness are extracted using established approaches from time-resolved CT images. The action potential dynamics and conduction are modeled using the classical monodomain model for transmembrane potential and an anisotropic diffusion model. The diffusivities and stimulus currents are iteratively varied to match the patient's EKG data and coupled to the LADT framework for personalizing tissue deformation and blood flow [1]. The effects of thickness (uniform vs. variable) and tissue structure (fiber directions, fibrosis, and passive and active material parameters) on the LA excitation-contraction patterns and blood flow are analyzed, with potential implications for studying the risk of clotting and stroke under pathological conditions, such as atrial fibrillation, flutter, and tachycardia.