Influence of Fibrotic Tissue Arrangement on Intracardiac Electrograms During Persistent Atrial Fibrillation

Abstract

Under persistent atrial fibrillation (peAF), cardiac tissue experiences electrophysiological and structural remodeling. Fibrosis in the atrial tissue has an important impact on the myocyte action potential and its propagation. The objective of this work is to explore the effect of heterogeneities present in the fibrotic tissue and their impact on the intracardiac electrogram (EGM). Human atrial myocyte and fibroblast electrophysiology was simulated using mathematical models proposed by Koivumäki et al. to represent electrical remodeling under peAF and the paracrine effect of the transforming grow factor 1 (TGF-1). 2D tissue simulations were computed varying the density of fibrosis (10%, 20% and 40%), myofibroblasts and collagen were randomly distributed with different ratios (0%-100%, 50%-50% and 100%-0%). Results show that increasing the fibrosis density changes the re-entry dynamics from functional to anatomical due to a block in conduction in regions with high fibrosis density (40%). EGM morphology was affected by different ratios of myofibroblasts-collagen. For low myofibroblast densities (below 50%) the duration of active segments was shorter compared to higher myofibroblasts densities (above 50%). Our results show that fibrosis heterogeneities can alter the dynamics of the re-entry and the morphology of the EGM. Figure 3. A)Mean duration of the active segment for different fibrosis densities and myofibroblasts vs. collagen ratios inside and outside the fibrotic region. As fibrosis density increases, the duration of the detected segment also increases. At 40% fibrosis density voltage becomes very small and block can occur. B) Mean Shannon Entropy for inside and outside of the fibrotic region. Different densities of fibrosis increase the Shannon Entropy, it is not significantly affected by the ratio of myofibroblasts vs. collagen.

Using Machine Learning to Characterize Atrial Fibrotic Substrate From Intracardiac Signals With a Hybrid in silico and in vivo Dataset

“…While our approach shows promising results and highlights the essential features of intracardiac signals to characterize atrial substrate, validation through independent experimental and clinical data is desirable. Future studies could include LGE-MRI data to validate the proposed approach and explore the arrangement of the fibrotic tissue effect on the electrogram morphology (Sánchez et al, 2019b).…”

A Multiscale in Silico Study to Characterize the Atrial Electrical Activity of Patients With Atrial Fibrillation. A Translational Study to Guide Ablation Therapy

“…When increasing the percentage of myofibroblast densities (above 50% compared to the percentage of collagen), propagation exhibited a slower frequency of activation, which was reflected in segments with a longer duration of activity. Adapted from [112] .…”

“…In this chapter, the fibrotic composition was varied, and the effect on electrical propagation and the electrograms was quantified. Part of this work was presented as a conference contribution [112].…”

“…Fractionated signals were mainly found with a mixture of myofibroblasts and collagen. Adapted from[112]…”

“…Different densities of fibrosis increase the Shannon Entropy, it is not significantly affected by the ratio of myofibroblasts vs. collagen. Adapted from[112]…”