scholarly journals Mechanisms of Atrial Fibrillation – Reentry, Rotors and Reality

2014 ◽  
Vol 3 (2) ◽  
pp. 90 ◽  
Author(s):  
Jonathan W Waks ◽  
Mark E Josephson ◽  
◽  
Keyword(s):  
Atrial Fibrillation ◽  
Clinical Practice ◽  
Catheter Ablation ◽  
20Th Century ◽  
Experimental Studies ◽  
Therapeutic Targets ◽  
Spiral Waves ◽  
Historical Understanding ◽  
New Strategies ◽  
Complex Fractionated Atrial Electrograms

Atrial fibrillation (AF) is the most common sustained arrhythmia encountered in clinical practice, yet our understanding of the mechanisms that initiate and sustain this arrhythmia remains quite poor. Over the last 50 years, various mechanisms of AF have been proposed, yet none has been consistently observed in both experimental studies and in humans. Recently, there has been increasing interest in understanding how spiral waves or rotors – which are specific, organised forms of functional reentry – sustain human AF and how they might be therapeutic targets for catheter-based ablation. The following review describes the historical understanding of reentry and AF mechanisms from earlier in the 20th century, advances in our understanding of mechanisms that are able to sustain AF with a focus on rotors and complex fractionated atrial electrograms (CFAEs), and how the study of AF mechanisms has resulted in new strategies for treating AF with novel forms of catheter ablation.

Abstract 5659: Regular Atrial Tachycardias After Ablation Of Complex Fractionated Atrial Electrograms (CFAE) For Atrial Fibrillation: Acute Incidence And Recurrence In Clinical Follow-up

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Tilko Reents ◽  
Gabriele Hessling ◽  
Stephanie Fichtner ◽  
Jinjin Wu ◽  
Heidi L Estner ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Catheter Ablation ◽  
Successful Ablation ◽  
Atrial Electrograms ◽  
Initial Procedure ◽  
The Impact ◽  
External Cardioversion ◽  
Complex Fractionated Atrial Electrograms

Background: The catheter ablation of atrial fibrillation (AF) can be performed by ablation of complex fractionated atrial electrograms (CFAE). Endpoint of CFAE ablation is the regularisation or termination of AF. However, the impact of regular atrial tachycardia (AT) occurring during CFAE ablation on long term outcome has not been investigated. Thus, it is not clear whether these tachycardias should be acutely targeted for ablation. Methods: In 43 patients (31 male, age 62±9 years with paroxysmal (15 patients), persistent (25 patietns) or permanent AF (3 patients) organisation of AF to regular AT was achieved by ablation of CFAE. Mapping of AT with subsequent successful ablation was performed in 14/43 patients (33%), in the remaining 29/43 patients (67%) AT was terminated with external cardioversion or pace overdrive. After ablation procedure, patients were seen in our out-patient clinic with repetitive Holter ECG after 1, 3, and subsequently every 3 months and were intensively screened for the occurrence of regular AT. Results: In follow-up 22/43 patients (51%) developed sustained AT necessitating in 20 patients repeat catheter ablation (12 patients) or external cardioversion (8 patients). AF had been paroxysmal in 7/22 and persisten in 15/22 patients with AT in follow-up. In 14/22 patients (63%), no attempt for ablation of AT had been made during the initial procedure, in 8/22 AT (36%) had been mapped and initially successful ablated. Of 21 patients without AT occurrence during follow-up, AF had been paroxysmal in 8/21 and persistent or permanent in 13/21 patients. AT had been mapped and ablated in 6 (29%) whereas in 15/21 patients (71%), AT had not been targeted. Ablation of AT during initial procedure, number of ablation applications, procedure and fluoroscopy duration were not predictive for freedom of AT in follow-up. Conclusion: In our study, mapping and successful ablation of new onset regular atrial tachycardias (AT) occurring during ablation of CFAE for atrial fibrillation was not predictive for the occurrence of AT in follow-up. Thus, results after termination of AT by cardioversion was in long-term comparable to sometimes time-consuming mapping/ablation for AT.

Abstract 18637: Recurrence Quantification Analysis to Distinguish Active From Passive Mechanisms of CFAEs During Catheter Ablation of Atrial Fibrillation

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Alex Baher ◽  
Anil K Gehi ◽  
Prabhat Kumar ◽  
Eugene Chung ◽  
Benjamin H Buck ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Catheter Ablation ◽  
Recurrence Quantification Analysis ◽  
Slow Conduction ◽  
Recurrence Quantification ◽  
Quantification Analysis ◽  
Mean Cycle ◽  
Recurrent Patterns ◽  
Wave Break ◽  
Complex Fractionated Atrial Electrograms

Background: Ablation of complex fractionated atrial electrograms (CFAEs) is controversial, primarily because of difficulty in visually distinguishing CFAEs representing an active site of driver activity from a passive site of double potentials, wave break, and/or slow conduction. We hypothesized that CFAEs within rotors in atrial fibrillation (AF) would exhibit highly recurrent behavior compared with CFAEs remote from these driver regions. Methods: Active and passive mechanisms of CFAE formation were simulated in several 2D 7.5 x 7.5 cm modified Luo-Rudy 1 models. CFAEs within areas of rotors were considered active, while those caused by wave break, slow conduction or double potentials remote from rotors were considered passive. Clinical signals were also collected during catheter ablation of paroxysmal AF (n=8 patients). An active driver CFAE site was defined by termination of AF with ablation followed by non-inducibility. A passive site was defined as CFAE occurring remotely. Detection of CFAEs was based on mean cycle length (MCL) calculated from 4 second windows using -dV/dt for detection (40ms refractory period/10ms maximum EGM width for simulations; 45ms/15ms respectively for clinical signals). Recurrence quantification analysis (RQA) was performed on discrete time series of simulated and clinical CFAE activations. Results: RQA was performed on 20 simulated EGMs. MCL was similar in both active and passive CFAEs (74±11ms and 78±6ms respectively, p=NS), but recurrence was significantly higher in active compared to passive sites (%recurrence: 61±22% active, 4±6% passive, p<0.01). In patients with AF, the driver sites were all located within the pulmonary vein antra while passive CFAEs were remote. The MCL of CFAEs at active driver sites was similar to that of passive sites (100±13ms active, 98±17ms passive, p=NS), but recurrence was significantly higher in the active driver sites (%recurrence: 18±15% active, 2±1% passive, p=0.02). Conclusion: CFAEs may occur due to either active or passive mechanisms. Sites within rotors or focal drivers of AF are more likely to exhibit recurrent patterns. RQA may be a powerful tool to differentiate driver from bystander CFAEs enabling more efficient targeting for ablation.

scholarly journals The Electrophysiology of Atrial Fibrillation: From Basic Mechanisms to Catheter Ablation

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Panagiotis Ioannidis ◽  
Theodoros Zografos ◽  
Evangelia Christoforatou ◽  
Konstantinos Kouvelas ◽  
Andreas Tsoumeleas ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Clinical Practice ◽  
Catheter Ablation ◽  
Sinus Rhythm ◽  
Pulmonary Vein ◽  
Basic Science ◽  
Advanced Technology ◽  
Atrial Myocardium ◽  
Pathophysiological Mechanisms ◽  
Basic Science Knowledge

The electrophysiology of atrial fibrillation (AF) has always been a deep mystery in understanding this complex arrhythmia. The pathophysiological mechanisms of AF are complex and often remain unclear despite extensive research. Therefore, the implementation of basic science knowledge to clinical practice is challenging. After more than 20 years, pulmonary vein isolation (PVI) remains the cornerstone ablation strategy for maintaining the sinus rhythm (SR). However, there is no doubt that, in many cases, especially in persistent and long-standing persistent AF, PVI is not enough, and eventually, the restoration of SR occurs after additional intervention in the rest of the atrial myocardium. Substrate mapping is a modern challenge as it can reveal focal sources or rotational activities that may be responsible for maintaining AF. Whether these areas are actually the cause of the AF maintenance is unknown. If this really happens, then the targeted ablation may be the solution; otherwise, more rough techniques such as atrial compartmentalization may prove to be more effective. In this article, we attempt a broad review of the known pathophysiological mechanisms of AF, and we present the recent efforts of advanced technology initially to reveal the electrical impulse during AF and then to intervene effectively with ablation.

Genetics of Atrial Fibrilation: In Search of Novel Therapeutic Targets

2019 ◽  
Vol 19 (3) ◽  
pp. 183-194 ◽  
Author(s):  
Estefanía Lozano-Velasco ◽  
Carlos Garcia-Padilla ◽  
Amelia E. Aránega ◽  
Diego Franco
Keyword(s):  
Atrial Fibrillation ◽  
Regulatory Networks ◽  
Association Studies ◽  
Redox Homeostasis ◽  
Experimental Studies ◽  
Point Mutations ◽  
Therapeutic Targets ◽  
Genetic Regulatory Networks ◽  
Nucleotide Polymorphisms ◽  
Novel Therapeutic

: Atrial fibrillation (AF) is the most frequent arrhythmogenic disease in humans, ranging from 2% in the general population and rising up to 10-12% in 80+ years. Genetic analyses of AF familiar cases have identified a series of point mutations in distinct ion channels, supporting a causative link. However, these genetic defects only explain a minority of AF patients. Genomewide association studies identified single nucleotide polymorphisms (SNPs), close to PITX2 on 4q25 chromosome, that are highly associated to AF. Subsequent GWAS studies have identified several new loci, involving additional transcription and growth factors. Furthermore, these risk 4q25 SNPs serve as surrogate biomarkers to identify AF recurrence in distinct surgical and pharmacological interventions. Experimental studies have demonstrated an intricate signalling pathway supporting a key role of the homeobox transcription factor PITX2 as a transcriptional regulator. Furthermore, cardiovascular risk factors such as hyperthyroidism, hypertension and redox homeostasis have been identified to modulate PITX2 driven gene regulatory networks. We provide herein a state-of-the-art review of the genetic bases of atrial fibrillation, our current understanding of the genetic regulatory networks involved in AF and its plausible usage for searching novel therapeutic targets.

Fuzzy decision tree to classify complex fractionated atrial electrograms

2015 ◽  
Vol 60 (3) ◽  
Author(s):  
Christopher Schilling ◽  
Matthias Keller ◽  
Daniel Scherr ◽  
Tobias Oesterlein ◽  
Michel Haïssaguerre ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Catheter Ablation ◽  
Decision Tree ◽  
Clinical Use ◽  
Fuzzy Decision ◽  
Fuzzy Decision Tree ◽  
Continuous Activity ◽  
Atrial Electrograms ◽  
Complete Set ◽  
Complex Fractionated Atrial Electrograms

AbstractCatheter ablation has emerged as an effective treatment strategy for atrial fibrillation (AF) in recent years. During AF, complex fractionated atrial electrograms (CFAE) can be recorded and are known to be a potential target for ablation. Automatic algorithms have been developed to simplify CFAE detection, but they are often based on a single descriptor or a set of descriptors in combination with sharp decision classifiers. However, these methods do not reflect the progressive transition between CFAE classes. The aim of this study was to develop an automatic classification algorithm, which combines the information of a complete set of descriptors and allows for progressive and transparent decisions. We designed a method to automatically analyze CFAE based on a set of descriptors representing various aspects, such as shape, amplitude and temporal characteristics. A fuzzy decision tree (FDT) was trained and evaluated on 429 predefined electrograms. CFAE were classified into four subgroups with a correct rate of 81±3%. Electrograms with continuous activity were detected with a correct rate of 100%. In addition, a percentage of certainty is given for each electrogram to enable a comprehensive and transparent decision. The proposed FDT is able to classify CFAE with respect to their progressive transition and may allow objective and reproducible CFAE interpretation for clinical use.

Sign in / Sign up

Export Citation Format

Share Document