The Major Role of IK1 in Mechanisms of Rotor Drift in the Atria: A Computational Study

Maintenance of paroxysmal atrial fibrillation (AF) by fast rotors in the left atrium (LA) or at the pulmonary veins (PVs) is not fully understood. This review describes the role of the heterogeneous distribution of transmembrane currents in the PVs and LA junction (PV-LAJ) in the localization of rotors in the PVs. Experimentally observed heterogeneities in IK1, IKs, IKr, Ito, and ICaL in the PV-LAJ were incorporated into models of human atrial kinetics to simulate various conditions and investigate rotor drifting mechanisms. Spatial gradients in the currents resulted in shorter action potential duration, less negative minimum diastolic potential, slower upstroke and conduction velocity for rotors in the PV region than in the LA. Rotors under such conditions drifted toward the PV and stabilized at the less excitable region. Our simulations suggest that IK1 heterogeneity is dominant in determining the drift direction through its impact on the excitability gradient. These results provide a novel framework for understanding the complex dynamics of rotors in AF.

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A Divergence-Based Approach for the Identification of Atrial Fibrillation Focal Drivers From Multipolar Mapping: A Computational Study

Frontiers in Physiology ◽

10.3389/fphys.2021.749430 ◽

2021 ◽

Vol 12 ◽

Author(s):

Michela Masè ◽

Alessandro Cristoforetti ◽

Maurizio Del Greco ◽

Flavia Ravelli

Keyword(s):

Atrial Fibrillation ◽

Vector Fields ◽

Computational Study ◽

Pulmonary Veins ◽

Proof Of Concept ◽

Activation Time ◽

Mapping Data ◽

Activation Patterns ◽

Novel Approach

The expanding role of catheter ablation of atrial fibrillation (AF) has stimulated the development of novel mapping strategies to guide the procedure. We introduce a novel approach to characterize wave propagation and identify AF focal drivers from multipolar mapping data. The method reconstructs continuous activation patterns in the mapping area by a radial basis function (RBF) interpolation of multisite activation time series. Velocity vector fields are analytically determined, and the vector field divergence is used as a marker of focal drivers. The method was validated in a tissue patch cellular automaton model and in an anatomically realistic left atrial (LA) model with Courtemanche–Ramirez–Nattel ionic dynamics. Divergence analysis was effective in identifying focal drivers in a complex simulated AF pattern. Localization was reliable even with consistent reduction (47%) in the number of mapping points and in the presence of activation time misdetections (noise <10% of the cycle length). Proof-of-concept application of the method to human AF mapping data showed that divergence analysis consistently detected focal activation in the pulmonary veins and LA appendage area. These results suggest the potential of divergence analysis in combination with multipolar mapping to identify AF critical sites. Further studies on large clinical datasets may help to assess the clinical feasibility and benefit of divergence analysis for the optimization of ablation treatment.

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Persistent Atrial Fibrillation: The Role of Left Atrial Posterior Wall Isolation and Ablation Strategies

Journal of Clinical Medicine ◽

10.3390/jcm10143129 ◽

2021 ◽

Vol 10 (14) ◽

pp. 3129

Author(s):

Riyaz A. Kaba ◽

Aziz Momin ◽

John Camm

Keyword(s):

Atrial Fibrillation ◽

Left Atrial ◽

Pulmonary Veins ◽

Treatment Strategies ◽

Persistent Atrial Fibrillation ◽

Posterior Wall ◽

Cardiovascular Death ◽

Good Effect ◽

Complex Forms

Atrial fibrillation (AF) is a global disease with rapidly rising incidence and prevalence. It is associated with a higher risk of stroke, dementia, cognitive decline, sudden and cardiovascular death, heart failure and impairment in quality of life. The disease is a major burden on the healthcare system. Paroxysmal AF is typically managed with medications or endocardial catheter ablation to good effect. However, a large proportion of patients with AF have persistent or long-standing persistent AF, which are more complex forms of the condition and thus more difficult to treat. This is in part due to the progressive electro-anatomical changes that occur with AF persistence and the spread of arrhythmogenic triggers and substrates outside of the pulmonary veins. The posterior wall of the left atrium is a common site for these changes and has become a target of ablation strategies to treat these more resistant forms of AF. In this review, we discuss the role of the posterior left atrial wall in persistent and long-standing persistent AF, the limitations of current endocardial-focused treatment strategies, and future perspectives on hybrid epicardial–endocardial approaches to posterior wall isolation or ablation.

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Heterogeneous and anisotropic integrative model of pulmonary veins: computational study of arrhythmogenic substrate for atrial fibrillation

Interface Focus ◽

10.1098/rsfs.2012.0069 ◽

2013 ◽

Vol 3 (2) ◽

pp. 20120069 ◽

Cited By ~ 28

Author(s):

Oleg V. Aslanidi ◽

Michael A. Colman ◽

Marta Varela ◽

Jichao Zhao ◽

Bruce H. Smaill ◽

...

Keyword(s):

Atrial Fibrillation ◽

High Frequency ◽

Computational Study ◽

Pulmonary Veins ◽

Three Dimensional ◽

Primary Source ◽

Integrative Model ◽

Micro Computed Tomography ◽

Three Dimensional Model ◽

Arrhythmogenic Substrate

Mechanisms underlying the genesis of re-entrant substrate for the most common cardiac arrhythmia, atrial fibrillation (AF), are not well understood. In this study, we develop a multi-scale three-dimensional computational model that integrates cellular electrophysiology of the left atrium (LA) and pulmonary veins (PVs) with the respective tissue geometry and fibre orientation. The latter is reconstructed in unique detail from high-resolution (approx. 70 μm) contrast micro-computed tomography data. The model is used to explore the mechanisms of re-entry initiation and sustenance in the PV region, regarded as the primary source of high-frequency electrical activity in AF. Simulations of the three-dimensional model demonstrate that an initial break-down of normal electrical excitation wave-fronts can be caused by the electrical heterogeneity between the PVs and LA. High tissue anisotropy is then responsible for the slow conduction and generation of a re-entrant circuit near the PVs. Evidence of such circuits has been seen clinically in AF patients. Our computational study suggests that primarily the combination of electrical heterogeneity and conduction anisotropy between the PVs and LA tissues leads to the generation of a high-frequency (approx. 10 Hz) re-entrant source near the PV sleeves, thus providing new insights into the arrhythmogenic mechanisms of excitation waves underlying AF.

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Role of Triggering Pulmonary Veins in the Maintenance of Sustained Paroxysmal Atrial Fibrillation

Pacing and Clinical Electrophysiology ◽

10.1111/pace.12121 ◽

2013 ◽

Vol 36 (7) ◽

pp. 845-854 ◽

Cited By ~ 5

Author(s):

VASSIL B. TRAYKOV ◽

RÓBERT PAP ◽

ZOLTÁN GINGL ◽

SZAMI CHADAIDE ◽

HARIS M. HAQQANI ◽

...

Keyword(s):

Atrial Fibrillation ◽

Paroxysmal Atrial Fibrillation ◽

Pulmonary Veins

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Imaging of pulmonary veins during catheter ablation for atrial fibrillation: the role of multi-slice computed tomography

EP Europace ◽

10.1093/europace/eun230 ◽

2008 ◽

Vol 10 (Supplement 3) ◽

pp. iii14-iii21 ◽

Cited By ~ 12

Author(s):

H. Niinuma ◽

R. T. George ◽

A. Arbab-Zadeh ◽

J. A.C. Lima ◽

C. A. Henrikson

Keyword(s):

Computed Tomography ◽

Atrial Fibrillation ◽

Catheter Ablation ◽

Pulmonary Veins

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A Computational Study of the Electrophysiological Substrate in Patients Suffering From Atrial Fibrillation

Frontiers in Physiology ◽

10.3389/fphys.2021.673612 ◽

2021 ◽

Vol 12 ◽

Author(s):

S. Pagani ◽

L. Dede' ◽

A. Frontera ◽

M. Salvador ◽

L. R. Limite ◽

...

Keyword(s):

Atrial Fibrillation ◽

Cardiac Electrophysiology ◽

Computational Study ◽

Pulmonary Veins ◽

Coupled System ◽

Density Mapping ◽

Slow Conduction ◽

Conduction Velocities ◽

Ectopic Beats

In the context of cardiac electrophysiology, we propose a novel computational approach to highlight and explain the long-debated mechanisms behind atrial fibrillation (AF) and to reliably numerically predict its induction and sustainment. A key role is played, in this respect, by a new way of setting a parametrization of electrophysiological mathematical models based on conduction velocities; these latter are estimated from high-density mapping data, which provide a detailed characterization of patients' electrophysiological substrate during sinus rhythm. We integrate numerically approximated conduction velocities into a mathematical model consisting of a coupled system of partial and ordinary differential equations, formed by the monodomain equation and the Courtemanche-Ramirez-Nattel model. Our new model parametrization is then adopted to predict the formation and self-sustainment of localized reentries characterizing atrial fibrillation, by numerically simulating the onset of ectopic beats from the pulmonary veins. We investigate the paroxysmal and the persistent form of AF starting from electro-anatomical maps of two patients. The model's response to stimulation shows how substrate characteristics play a key role in inducing and sustaining these arrhythmias. Localized reentries are less frequent and less stable in case of paroxysmal AF, while they tend to anchor themselves in areas affected by severe slow conduction in case of persistent AF.

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Prospective Randomized Clinical Trial of Wide Area Circumferential Pulmonary Vein Ablation versus Segmental Pulmonary Vein Ablation for Pulmonary Vein Isolation as a Treatment for Short-Duration Paroxysmal Atrial Fibrillation

10.22541/au.161196037.76727054/v1 ◽

2021 ◽

Author(s):

Sapan Bhuta ◽

Gustaf Sverin ◽

Hiro Kawata ◽

Malek Bashti ◽

Jessica Hunter ◽

...

Keyword(s):

Atrial Fibrillation ◽

Pulmonary Vein ◽

Short Duration ◽

Pulmonary Vein Isolation ◽

Paroxysmal Atrial Fibrillation ◽

Pulmonary Veins ◽

Wide Area ◽

Pulmonary Vein Ablation ◽

Total Procedure Time

Background: Previous studies suggest that wide area circumferential pulmonary vein ablation (WACA) is more effective than segmental pulmonary vein ablation (SPVA) for pulmonary vein isolation (PVI) for treatment of atrial fibrillation. Whether this is true in patients (pts) with very short duration paroxysmal atrial fibrillation (PAF) is unknown. Objective: To compare WACA to SPVA in pts with PAF lasting <48 hours. Methods: One hundred pts with PAF <48 hours were randomized to either WACA vs SPVA (45 and 53 pts respectively, with 2 withdrawals), and followed up for 24 months with 14-day ECGs every 6 months. Results: Among 97 pts at an average of 22.1±4.8 months followup, 26 (57.8%) remained free of any atrial arrhythmias after WACA versus 29 (55.86%) after SPVA (p=0.64). Sixteen pts (35.6%) had recurrent PAF after WACA versus 20 pts (38.5%) after SPVA (p=0.79). Seven pts (15.6%) had atrial flutter after WACA versus 5 pts (9.64%) after SPVA (p=0.376) and 1 pt (2.2%) had atrial tachycardia after WACA vs 1 pt (1.9%) after SPVA (p=0.918). Total procedure time was lower for SPVA vs WACA (242.9 vs 271.1 minutes, p= 0.047), and fluoroscopy time similar for WACA vs SPVA (50.8 vs 53.4 minutes, p=0.555). Conclusions: As an initial ablation approach in pts with PAF <48 hours, SPVA was similarly effective to WACA with respect to arrhythmia recurrence, supporting the central role of the pulmonary veins for maintaining AF in these pts. Future therapies using alternative ablation energies may incorporate these insights to reduce risk to gastroesophageal structures.

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Evaluation of Left Atrial Anatomy and Function using Multidetector Computed Tomography in Patients Undergoing Catheter Ablation for Atrial Fibrillation

Medical Visualization ◽

10.24835/1607-0763-2017-5-39-55 ◽

2017 ◽

pp. 39-55 ◽

Cited By ~ 2

Author(s):

V. I. Gurina ◽

E. V. Kondrat’ev ◽

A. Sh. Revishvily ◽

M. Z. Alimurzaeva

Keyword(s):

Atrial Fibrillation ◽

Left Atrium ◽

Pulmonary Veins ◽

Systemic Review ◽

Free Access ◽

Contrast Enhanced ◽

Review Reports ◽

And Function

Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice. Сatheter ablation (CA) of arrhythmogenic foci is supposed to be an established treatment option for symptomatic patients with AF, refractory to antiarrhythmic therapy. Pre-procedural imaging is indispensable for the assessment of left atrium, pulmonary veins and adjacent anatomy, and facilitates selection of the ablation strategy to achieve an optimal result and minimize the risk of complications.Purpose: to evaluate the role of contrast-enhanced MDCT in patients with AF; also to present the prospects for further development of this method according to the systemic review of world research data.Materials and methods. 140 free access articles requested as “MDCT left atrium”, “MDCT pulmonary veins”, “MDCT atrial appendage” from 01.2009 until 01.2017 were analyzed in PubMed, as well as a number of Russianlanguage articles in eLibrary.Results.This literature review reports and systematizes available data on epidemiology and mechanisms of AF, represents current classification. In addition were analyzed advantages of MDCT over other methods of visualization while planning the CA and follow-up.Conclusion.MDCT is precise, effective and accessible option, which satisfies visualization requirements during the preparation for CA. Moreover, using MDCT in combination with electro-mapping systems increases safety and effectiveness of the procedure. In postoperative period MDCT can be used for complications diagnostic and results assessment.

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