Mechanisms of Wave Fractionation at Boundaries of High-Frequency Excitation in the Posterior Left Atrium of the Isolated Sheep Heart During Atrial Fibrillation

Kalifa, Jérôme; Tanaka, Kazuhiko; Zaitsev, Alexey V.; Warren, Mark; Vaidyanathan, Ravi; Auerbach, David S.; Pandit, Sandeep V.; Vikstrom, Karen L.; Ploutz‐Snyder, Robert; Talkachou, Arkadzi; Atienza, Felipe; Guiraudon, G; Jalife, José; Berenfeld, Omer

doi:10.1161/circulationaha.105.575340

Cited by 374 publications

(301 citation statements)

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“…It is noteworthy that, in our population, spectral turbulence, starting during the first seven days in sinus rhythm, was mostly concentrated in the terminal portion (second half, Figure 2) of the P-wave. The temporal relationship of the high-frequency content detected on the P-wave in the present study is in accordance, at least in part, with the high-frequency fragmentation registered in left atrium during atrial fibrillation by Kalifa et al 33 .…”

Section: (B) Mec (%) (C) Sec (%) (D) Met (Hz) (E) Set (Hz)supporting

confidence: 93%

“…Other studies have demonstrated a strong correlation between fractionated endocardial electrograms and AF episodes 33,34 . Fragmented ventricular activation detected by endocardial electrograms has been already correlated with low-amplitude and high-frequency signals detected on body surface SAECG 35,36 .…”

Section: (B) Mec (%) (C) Sec (%) (D) Met (Hz) (E) Set (Hz)mentioning

confidence: 87%

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Remodelagem atrial elétrica reversa após cardioversão de fibrilação atrial isolada de longa duração

Barbosa¹,

Benchimol-Barbosa²,

Bomfim³

et al. 2009

Arq. Bras. Cardiol.

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Background: Atrial fibrillation (AF) itself promotes electrophysiological changes, termed "electrical remodeling", facilitating its recurrence and maintenance. There is evidence that the remodeling process is reversible after restoration of the sinus rhythm (SR). However, the timing for the recovery of electrophysiological properties is still undefined.Objctive: The aim of this study was to assess the atrial electrical activation using P-wave signal-averaged electrocardiogram (P-SAECG) post-cardioversion of long-standing AF, focusing on the reversal remodeling process to identify the timing of the process stabilization.Methods: Subjects with lone persistent AF, eligible for cardioversion and successfully converted to SR, were enrolled at the study. SAECG was performed immediately after reversion to SR and repeated on days seven and thirty.Results: Of 31 subjects, nine presented early recurrence of atrial fibrillation, all of them in the first seven days postcardioversion; 22 remained in SR for at last one month and SAECG was obtained on days seven and thirty after cardioversion. In the latter, P-wave duration progressively abated from the first to the third SAECG (P-wave duration: 185.5±41.9 ms vs 171.7±40.5 ms vs 156.7±34.9 ms, respectively, first, second and third SAECG; p<0.001 for all matches). In the frequency domain analysis, spectral turbulence was not apparent in SAECG immediately postcardioversion, but sharply increased on day seven and remained unchanged on day thirty. Conclusion IntroductionAtrial fibrillation (AF) has been described as a selfperpetuating arrhythmia, which promotes electrophysiological changes in atrial tissue, facilitating its recurrence and maintenance [1][2][3][4][5] . Persistent AF usually progresses to a permanent form and the successful restoration and maintenance of sinus rhythm largely depend on arrhythmia duration, with longstanding AF being more resistant to cardioversion and more prone to recurrence [6][7][8][9] . Both resistance to cardioversion and tendency of recurrence are strongly related to the development of electrophysiological substrates characterized by shortened atrial effective refractory period 2,4,5,[10][11][12][13] , slow conduction in the atrial myocardium 10,11,[14][15][16] and dispersion of refractoriness 4,13,17,18 . These changes can be induced by both rapid atrial pacing and AF itself, and have been termed "electrical remodeling" 2 . The resultant electrophysiological abnormality is the presence of multiple wavelets around the atria, some of which circle back on them creating multiples reentry circuits, as proposed by Moe et al 19,20 in 1962 and 1964, and later confirmed by Allessie et al 21 in 1985.In animal models, the remodeling process has been demonstrated to be reversible after restoration of the sinus rhythm, and is characterized by progressive increase in both atrial conduction velocity and refractoriness (reversal remodeling) 1,2,10,11,13,22 . Recovery has also been demonstrated in human atria 3,[23][24][25][26] . On the other hand, a remarkab...

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Section: (B) Mec (%) (C) Sec (%) (D) Met (Hz) (E) Set (Hz)supporting

confidence: 93%

Section: (B) Mec (%) (C) Sec (%) (D) Met (Hz) (E) Set (Hz)mentioning

confidence: 87%

Remodelagem atrial elétrica reversa após cardioversão de fibrilação atrial isolada de longa duração

Barbosa¹,

Benchimol-Barbosa²,

Bomfim³

et al. 2009

Arq. Bras. Cardiol.

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“…It has been further proposed that these fractionated sites are important in sustaining AF, 53 and that targeting fractionated electrograms with ablation can terminate AF and prevent its re-induction or recurrence. 52,[54][55][56][57][58][59][60] The data supporting these conclusions are rather weak overall, with only a few small, randomised clinical trials providing guidance, and different studies have arrived at disparate conclusions regarding the importance, or lack thereof, of fractionated electrograms in the pathogenesis of AF.…”

Section: Limitations Of Targeting Rotors With Ablation For the Treatmmentioning

confidence: 99%

Mechanisms of Atrial Fibrillation – Reentry, Rotors and Reality

Waks

Josephson²

2014

Arrhythmia &Amp; Electrophysiology Review

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Atrial fibrillation (AF), the most common sustained arrhythmia, is a leading cause of stroke, and is associated with significant morbidity and mortality worldwide. Despite its frequency, clinical importance, and advances in technology and our knowledge of the molecular, ionic and physiological fundamentals of cardiac electrophysiology, our limited understanding of the mechanisms that initiate and sustain AF has prevented us from being able to truly cure this arrhythmia with antiarrhythmic drugs and/or ablation. This contrasts with other arrhythmias, such as AV nodal tachycardia or circus movement tachycardia using an accessory pathway, which have well-defined mechanisms and circuits that can be safely targeted with high rates of cure. The observations that AF may have different mechanisms in different patients, and that paroxysmal, persistent and permanent forms of AF may differ in how they are initiated and sustained, only serves to reinforce our lack of understanding of this ubiquitous arrhythmia. Historical Mechanisms of Atrial Fibrillation and the Multiple Wavelet HypothesisInterest and understanding of the mechanism of AF began to take form in the early 1900s. Given the chaotic and irregular nature of AF on the surface electrocardiogram, rapid firing of automatic atrial foci was considered a potential mechanism. However, after the seminal work of Mayer 1 , Mines 2 and Garrey 3 in laying the foundation for describing and understanding reentrant arrhythmias, atrial reentrant circuits emerged as the likely drivers of AF.4-7 Although these theories were conceptually sound, it was impossible to prove a specific mechanism with the technology of the time. Moe et al. demonstrated that it was probabilistically unlikely that a large number of simultaneous wavefronts would all die out simultaneously, and AF would therefore perpetuate. However, if the number of simultaneous wavelets were small and/or below a critical value (between 15 and 30 in Moe's computer model), 9 at some point all reentrant wavefronts would be simultaneously extinguished, and AF would therefore terminate. 8,9 Allessie et al. provided experimental evidence supporting this mechanism in a canine heart model of AF where four to six simultaneous reentrant wavelets were needed to sustain arrhythmia. 10 Further evidence supporting multiple wavelets in AF was demonstrated in a separate model, which evaluated the effect of various antiarrhythmic drugs on canine myocardium. This model demonstrated that termination of AF was associated with a reduction AbstractAtrial 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 -su...

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“…5 To further rationalize the use of CFAE and DF for ablation guidance, Kalifa et al demonstrated in isolated sheep hearts that these two measures may be predictably organized, whereby the most fractionated activity is found at the periphery of a source region having the highest activation rate. 8 In addition, experimental 9;10 and clinical 11 mapping studies have indicated that functional reentry underlies the highest activation rate and the maintenance of AF. However, the relationship between the spatiotemporal stability of such reentrant drivers and the fractionation and rate of the activation in their periphery has not been studied yet.…”

Section: Introductionmentioning

confidence: 99%

Rotor meandering contributes to irregularity in electrograms during atrial fibrillation

Zlochiver¹,

Yamazaki²,

Kalifa³

et al. 2008

Heart Rhythm

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Radiofrequency ablation therapy of atrial fibrillation (AF) recently incorporated the analysis of dominant frequency (DF) and/or electrogram fractionation for guidance. However, the relationships between DF, fractionation and spatio-temporal characteristics of the AF source remain unclear. We hypothesize that meandering reentrant AF source contributes to the wave fractionation and is reflected in the power spectrum of local electrograms elsewhere in the rotor's surroundings.Methods-Meandering rotors as AF sources were simulated in 2D models of human atrial tissue and recorded in isolated sheep hearts. Non-dominant elements of the signals were differentiated from the dominant elements using singular value decomposition, whereby the purely periodic constituent (PC) relating to the rotor's DF was eliminated rendering a residual constituent (RC) that consisted of all other activity.Results-Spectral analysis of the decomposed constituents revealed peaks corresponding to the meandering frequency of the rotor tip, the magnitudes of which were proportional to the size of, and the distance to the rotor core. Similar analyses on epicardial optical signals and electrograms from isolated sheep hearts, as well as human complex fractionated atrial electrograms demonstrated applicability of the approach.Conclusion-Increased meandering of the rotor driving AF reduces activation periodicity and increases fractionation. The spectral manifestation of the rotor activity beyond the meandering region makes it possible to characterize AF source stability, as well as DF in humans using electrode mapping.

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Mechanisms of Wave Fractionation at Boundaries of High-Frequency Excitation in the Posterior Left Atrium of the Isolated Sheep Heart During Atrial Fibrillation

Cited by 374 publications

References 30 publications

Remodelagem atrial elétrica reversa após cardioversão de fibrilação atrial isolada de longa duração

Remodelagem atrial elétrica reversa após cardioversão de fibrilação atrial isolada de longa duração

Mechanisms of Atrial Fibrillation – Reentry, Rotors and Reality

Rotor meandering contributes to irregularity in electrograms during atrial fibrillation

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