Atrial Electrophysiology and Mechanisms of Atrial Fibrillation

2003 ◽  
Vol 8 (1_suppl) ◽  
pp. S5-S11 ◽  
Author(s):  
Stanley Nattel
Keyword(s):  
Atrial Fibrillation ◽  
Atrial Tachycardia ◽  
Scientific Basis ◽  
Clinical Settings ◽  
Genetic Determinants ◽  
Atrial Electrophysiology ◽  
Arrhythmia Mechanisms ◽  
Fibrillatory Conduction ◽  
Insight Into

Atrial fibrillation is the most common cardiac arrhythmia in clinical practice, and its management remains challenging. A solid understanding of the scientific basis for atrial fibrillation therapy requires insight into the mechanisms underlying the arrhythmia, about which an enormous amount has been learned over the past 10 years. The basic information presently available about atrial fibrillation mechanisms is reviewed. The particular properties of normal atrial electrophysiology are discussed, including salient ionic determinants of the atrial action potential and key anatomic features. Reviewed are three crucial arrhythmia mechanisms long held to be involved in atrial fibrillation: 1) rapid ectopic activity, 2) single-circuit reentry with fibrillatory conduction, and 3) multiple-circuit reentry. The determinants of each and the evidence for their involvement in clinical and/or experimental atrial fibrillation are noted. The physiological consequences, various contributing mechanisms, and clinical implications of the role of atrial-tachycardia remodeling are analyzed. Atrial-tachycardia remodeling links the potential mechanisms of atrial fibrillation, since atrial fibrillation beginning by any mechanism is likely to cause tachycardia-remodeling and thus promote the maintenance of atrial fibrillation by multiple-circuit reentry. Atrial structural remodeling is discussed as a paradigm of atrial fibrillation in which the classic features required for reentry (reduced refractory period and reentrant wavelength) may be lacking. Finally, the importance of recent insights into potential genetic determinants of atrial fibrillation is reviewed. The classic understanding of atrial fibrillation pathophysiology saw the different possible mechanisms as being alternative and opposing hypotheses. We now consider the multiple potential mechanisms as contributing to the pathophysiology of the arrhythmia to a different extent in different clinical settings and interacting with each other in a dynamic way at various stages of the natural history in many patients. It is hoped that this improved mechanistic understanding will lead to the development of improved therapeutic options.

Abstract 18492: Phase Analysis Detects Human Atrial Fibrillation Sources While Classical Activation Mapping May Not: Reconciling Classical and Computational Mapping

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Junaid A Zaman ◽  
Gautam G Lalani ◽  
Tina Baykaner ◽  
Shirley Park ◽  
David E Krummen ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Phase Analysis ◽  
Atrial Tachycardia ◽  
Source Detection ◽  
Perfect Agreement ◽  
Classical Activation ◽  
Electrode Noise ◽  
Fibrillatory Conduction ◽  
Activation Mapping ◽  
Human Atrial Fibrillation

Introduction: The mechanisms maintaining human persistent AF are elusive. It is striking how most optical mapping studies in animal and recently human AF show rotors and focal sources, while most classical activation mapping studies of electrograms do not. We tested the hypothesis that sites in human persistent AF showing rotors by phase analysis may, due to precession (‘wobble’) and fibrillatory collision, rarely reveal sources in activation maps. Methods: We studied 25 patients with persistent AF (LA 47 mm, CHADS2=1.9), in whom phase-mapping of electrograms from 64 pole baskets revealed rotors/focal sources where ablation terminated AF. Electrograms (fig A) were annotated (Matlab) using minimum dV/dt (unipoles, fig B) and peak amplitude criteria (bipoles) to create contours (isochrones), that were classified into a) complete, b) partial or c) unresolvable sources. Results: In each case, ablation at phase-identified rotors/sources (4.0±5.7 mins) terminated persistent AF to sinus rhythm (fig C, 64%) or atrial tachycardia. Notably, isochrones detected sources in only 5/25 (20%) of cases (fig D), more easily in unipolar than bipolar signals. Isochrones revealed partial sources in 11 (44%) and were unresolvable in 9 (36%). Source detection in classical maps was obscured by low signal: noise, varying sequence (rotor precession), or electrode noise that phase analysis resolved by analyzing neighboring sites (fig E). The figure summarizes these steps for a case with perfect agreement between activation and phase maps. Conclusions: Rotors and focal sources for human persistent AF detected by phase analysis were mostly undetected in activation maps, due to rotor precession and fibrillatory conduction. These data may inform approaches to revise classical criteria to better map AF.

scholarly journals Coronary Sinus Ablation Is a Key Player Substrate in Recurrence of Persistent Atrial Fibrillation

Cardiology ◽  
2019 ◽  
Vol 143 (3-4) ◽  
pp. 107-113 ◽  
Author(s):  
Naseer Ahmed ◽  
Shahida Perveen ◽  
Adeela Mehmood ◽  
Gulab Fatima Rani ◽  
Giulio Molon
Keyword(s):  
Atrial Fibrillation ◽  
Pulmonary Vein ◽  
Coronary Sinus ◽  
Pulmonary Veins ◽  
Persistent Atrial Fibrillation ◽  
Arrhythmogenic Substrate ◽  
Electrophysiological Procedures ◽  
Very High ◽  
Insight Into

Atrial fibrillation (AF) is the most frequent atrial arrhythmia. During the last few decades, owing to numerous advancements in the field of electrophysiology, we reached satisfactory outcomes for paroxysmal AF with the help of ablation procedures. But the most challenging type is still persistent AF. The recurrence rate of AF in patients with persistent AF is very high, which shows the inadequacy of pulmonary vein isolation (PVI). Over the last few decades, we have been trying to gain insight into AF mechanisms, and have come to the conclusion that there must be some triggers and substrates other than pulmonary veins. According to many studies, PVI alone is not enough to deal with persistent AF. The purpose of our review is to summarize updates and to clarify the role of coronary sinus (CS) in AF induction and propagation. This review will provide updated knowledge on developmental, histological, and macroscopic anatomical aspects of CS with its role as arrhythmogenic substrate. This review will also inform readers about application of CS in other electrophysiological procedures.

scholarly journals Role of Rotors in the Ablative Therapy of Persistent Atrial Fibrillation

2015 ◽  
Vol 4 (1) ◽  
pp. 47 ◽  
Author(s):  
Amir A Schricker ◽  
Junaid Zaman ◽  
Sanjiv M Narayan ◽  
◽  
◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Persistent Atrial Fibrillation ◽  
Contact Mapping ◽  
Long Term Follow Up ◽  
Fibrillatory Conduction ◽  
Procedural Success ◽  
Maintain Sinus Rhythm

Atrial fibrillation (AF) ablation is increasingly used to maintain sinus rhythm yet its results are sub-optimal, especially in patients with persistent AF or prior unsuccessful procedures. Attempts at improvement have often targeted substrates that sustain AF after it is triggered, yet those mechanisms are debated. Many studies now challenge the concept that AF is driven by self-sustaining disordered wavelets, showing instead that localised drivers (rotors) may drive disorder via a process known as fibrillatory conduction. Novel mapping using wide-area recordings, physiological filtering and phase analysis demonstrates rotors in human AF. Contact mapping with focal impulse and rotor modulation (FIRM) shows that localised ablation at sources can improve procedural success in many populations on long-term follow up and some newer approaches to rotor mapping are qualitatively similar. This review critically evaluates the data on rotor mapping and ablation, which advances our conceptual understanding of AF and holds the promise of substantially improving ablative outcomes in patients with persistent AF.

scholarly journals Role of Magnetic Resonance Imaging of Atrial Fibrosis in Atrial Fibrillation Ablation

2013 ◽  
Vol 2 (2) ◽  
pp. 124 ◽  
Author(s):  
David D Spragg ◽  
Irfan Khurram ◽  
Saman Nazarian ◽  
◽  
◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Magnetic Resonance ◽  
Resonance Imaging ◽  
Atrial Fibrosis ◽  
Complex Interplay ◽  
Af Ablation ◽  
Atrial Electrophysiology ◽  
Arrhythmogenic Substrate ◽  
Derived Data

Atrial fibrillation (AF) likely involves a complex interplay between triggering activity, usually from pulmonary vein foci, and maintenance of the arrhythmia by an arrhythmogenic substrate. Both components of AF, triggers and substrate have been linked to atrial fibrosis and attendant changes in atrial electrophysiology. Recently, there has been a growing use of imaging modalities, particularly cardiac magnetic resonance (CMR), to quantify the burden of atrial fibrosis and scar in patients either undergoing AF ablation, or who have recently had the procedure. How to use the CMR derived data is still an open area of investigation. The aim of this article is to summarise what is known as atrial fibrosis, as assessed by traditional catheter-based techniques and newer imaging approaches, and to report on novel efforts from our group to advance the use of CMR in AF ablation patients.

Ivabradine as a stabilising anti-arrhythmic agent for multifocal atrial tachycardia

2020 ◽  
Vol 30 (6) ◽  
pp. 899-902
Author(s):  
Mitchell I. Cohen ◽  
Jordan A. Cohen ◽  
Connor Shope ◽  
Lauren Stollar ◽  
Lucas Collazo
Keyword(s):  
Atrial Fibrillation ◽  
Extracorporeal Membrane Oxygenation ◽  
Sinus Rhythm ◽  
Critically Ill ◽  
Paroxysmal Atrial Fibrillation ◽  
Atrial Tachycardia ◽  
Blocking Agent ◽  
First Report ◽  
Membrane Oxygenation ◽  
Fibrillatory Conduction

AbstractMultifocal atrial tachycardia has certain electrocardiographic similarities to atrial fibrillation. The mechanism of atrial fibrillation is heterogenous but in some cases may arise from a single ectopic driver with fibrillatory conduction to the rest of the atria. This has led to the speculation that multifocal atrial tachycardia may have a similar mechanistic unifocal site that disperses through the atrium in a fibrillatory pattern. Ivabradine has been reported to be efficacious in an adult with paroxysmal atrial fibrillation as well as in children with junctional or ectopic atrial tachycardias. This is the first report of successfully using ivabradine, a novel anti-arrhythmic If blocking agent, to convert multifocal atrial tachycardia in a 5-month-old critically ill infant to a pattern indicating a single ectopic atrial focus. This allowed the patient’s single atrial focus to be ablated with return to sinus rhythm and decannulation from ventriculoarterial extracorporeal membrane oxygenation. This case suggests that multifocal atrial tachycardia may arise from a single automatic focus with downstream fibrillatory conduction to the atria.

scholarly journals Role of various signalling mechanism in pathogenesis and therapeutics of obesity

2019 ◽  
Vol 10 (4) ◽  
pp. 3398-3408
Author(s):  
Yash Prashar ◽  
Nilesh J Patel
Keyword(s):  
Energy Expenditure ◽  
Eating Behaviour ◽  
Treatment Strategies ◽  
Research Area ◽  
Scientific Basis ◽  
Energy Regulation ◽  
Obesity Therapy ◽  
Pathogenesis Related ◽  
Insight Into

This paper is a summary of appetite pathogenesis, therapy, and various mechanisms involved in obesity. Pathogenesis related to obesity deals with energy expenditure physiology and energy intake. The pathogenesis of obesity also contributes to energy regulation. Obesity usually happens when the consumption of energy is more than energy expenditure. It also includes relative research of monogenetic triggers contributing to deficiency of nutrition consumption and depression in key legislation. Obesity therapy involves the finding of hormones, neuropeptides, receptors, and transcription factors that involve the growth and regulation of eating behaviour, metabolic rate, and adipocyte. This paper also deals with various pathways which have a huge scientific basis in research in obesity. This review also focusses on the relation the pathways share by bringing them under one preview to understand their importance in the research area of obesity. It also includes comparative research and study work, which included the role and importance of various mediators like PYY, Ghrelin, Leptin, Adiponectin, along with inflammatory mediators like TNF Alpha and Interleukins. An insight into the role of oxidative stress highlighting its role and importance in obesity is also reviewed. Obesity therapy overview as well as newer strategies are also discussed. It also includes the methodology of exploration and obesity treatment in a novel way. Overall the review is a blend that incorporates major problems along with the latest treatment strategies to understand the demonic nature of this disease.

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