An Image-Based Model of Atrial Muscular Architecture

Abstract

Background-Computer models that capture key features of the heterogeneous myofiber architecture of right and left atria and interatrial septum provide a means of investigating the mechanisms responsible for atrial arrhythmia. The data necessary to implement such models have not previously been available. The aims of this study were to characterize surface geometry and myofiber architecture throughout the atrial chambers and to investigate the effects of this structure on atrial activation. Methods and Results-Atrial surface geometry and myofiber orientations were reconstructed in 3D at 50ϫ50ϫ50-m

Three‐dimensional Integrated Functional, Structural, and Computational Mapping to Define the Structural “Fingerprints” of Heart‐Specific Atrial Fibrillation Drivers in Human Heart Ex Vivo

“…The atrial roof and LRA regions were dominated by major muscular bundles, the extension of Bachmann's bundle, crista terminalis, and pectinate muscles, where myofibers were organized and oriented along the long axis of the bundles. Other areas throughout the human atria were characterized by more disorganized fiber orientations 15, 30…”

“…The structure tensor approach utilized the signal intensity variation of the CE‐MRI images and 3D Eigen‐analysis to estimate 3D fiber orientations by modeling local fiber alignment as the orientation with the least signal variation (Figures 6 and 7), as described in detail in our previous work 15, 19, 24…”

“…In this study, we have adapted the simplified 3‐current Fenton‐Karma cellular activation models to recreate the optically recorded regional conduction velocities and action potential durations (APDs) in the PLA region from the same heart, which was then applied across both atria of the model (Figure 8). 15, 28 Atrial 3D geometry with a resolution of 180 μm 3 including accurate wall thickness, myofiber orientations, and transmural fibrosis, was integrated with the adapted cellular model into a 3D computer model. Electrical conductivities were set at an anisotropic ratio of 9:1, which led to ≈3:1 regional anisotropic ratio for conduction velocities along the long axis of the cell and allowed the proper reproduction of the experimentally mapped conduction velocities as utilized by previous atrial modeling studies 4, 15.…”

“…15, 28 Atrial 3D geometry with a resolution of 180 μm 3 including accurate wall thickness, myofiber orientations, and transmural fibrosis, was integrated with the adapted cellular model into a 3D computer model. Electrical conductivities were set at an anisotropic ratio of 9:1, which led to ≈3:1 regional anisotropic ratio for conduction velocities along the long axis of the cell and allowed the proper reproduction of the experimentally mapped conduction velocities as utilized by previous atrial modeling studies 4, 15. Fibrosis and simulated ablation lesion lines were modeled as nonconducting tissue 4, 29.…”

“…Large‐animal structural models, such as sheep15, 16 and goats,17 have been used to investigate myofiber structure and surface geometry of the intact atria and progress has been made in defining the mechanisms of AF in animal models 4, 18. However, the interspecies difference in atrial structure and physiology may diminish the translational applications of these models to human AF 7.…”