Concurrent multiple left atrial focal activations with fibrillatory conduction and right atrial focal or reentrant activation as the mechanism in atrial fibrillation

Nitta, Takashi; Ishii, Yôsuke; Miyagi, Yasuo; Ohmori, Hiroya; Sakamoto, Shun–ichiro; Tanaka, Shigeo

doi:10.1016/j.jtcvs.2003.05.001

Cited by 110 publications

(84 citation statements)

References 19 publications

(17 reference statements)

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“…2,13,19 The study by de Groot et al 2 postulates transmural conduction of fibrillation waves as the leading mechanism of epicardial breakthrough, whereas many others use radial spread of activation as criterion to identify ectopic focal discharges during AF. [20][21][22][23][24] Using radial spread of activation and QS electrogram morphology as criterion for ectopy, Lee et al 25 recently demonstrate that AF in dogs undergoing vagal stimulation can be maintained by multiple ectopic foci.…”

Section: Discussionmentioning

confidence: 99%

Transmural Conduction Is the Predominant Mechanism of Breakthrough During Atrial Fibrillation

Eckstein

Zeemering

Linz

et al. 2013

Circ: Arrhythmia and Electrophysiology

138

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Present hypotheses on mechanisms underlying breakthrough events include transmural conduction from the opposing layer of the atrial wall (endo-epicardial or vice versa), transmural microreentry, or ectopic focal discharges. 2,[5][6][7][8][9][10][11][12] Electric dissociation between the endocardial bundle network and the epicardial layer (EED) during AF is a prerequisite condition for transmural conduction of fibrillation waves because only in the presence of EED electric activity in 1 layer of the atrial wall can encounter excitable tissue in the opposing layer.We recently demonstrated that in goats EED increases during the first 6 months of AF, 13 which might well explain the higher incidence of breakthrough in complex substrates for AF. However, increasing evidence for altered intracellular Ca 2+ handling in atrial myocytes of AF patients supports the hypothesis that ectopic focal discharges because of triggered activity might also occur during AF and contribute to its perpetuation. 9,12,14 © 2013 American Heart Association, Inc. Background-Endo-epicardial dissociation (EED) of electric activations resulting in transmural conduction of fibrillation waves (breakthroughs) has been postulated to contribute to the complexity of the substrate of atrial fibrillation (AF). The aim of this study was to elucidate the correlation between EED and incidence of breakthrough and to test the plausibility of transmural conduction versus ectopic focal discharges as sources of breakthrough. Methods and Results-We analyzed high-resolution simultaneous endo-epicardial in vivo mapping data recorded in left atrial free walls of goats with acute AF, 3 weeks and 6 months of AF (all n=7). Waves were analyzed for number, size, and width and categorized according to their origin outside (peripheral wave) or within the mapping area (breakthrough). Breakthrough incidence was lowest (2.1±1.0%) in acute AF, higher (11.4±6.1%) after 3 weeks (P<0.01 versus acute AF) and highest (14.2±3.8%) after 6 months AF (P<0.001 versus acute AF) and similar in the epicardium and endocardium. Most of the breakthroughs (86%; n=564) could be explained by transmural conduction, whereas only 13% (n=85) could be explained by ectopic focal discharges. Transmural microreentry did not play a role as source of breakthrough. Conclusions-This is the first study to present simultaneous endo-epicardial in vivo mapping data at sites of breakthrough events. Breakthrough incidence and degree of EED increased with increasing AF substrate complexity. In goat left atrial free walls, most of the breakthroughs can be explained by transmural conduction, whereas ectopic focal discharges play a limited role as source of breakthrough. (Circ Arrhythm Electrophysiol. 2013;6:334-341.) Circ Arrhythm Electrophysiol

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Section: Discussionmentioning

confidence: 99%

Transmural Conduction Is the Predominant Mechanism of Breakthrough During Atrial Fibrillation

Eckstein

Zeemering

Linz

et al. 2013

Circ: Arrhythmia and Electrophysiology

138

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“…7 In addition, Sahadevan et al 36 have observed regular short CL activity, predominantly from the LA, in patients with chronic AF and suggested that the posterior LA may be responsible for maintaining chronic AF. However, Nitta et al 37 have observed the existence of multiple LA and RA focal activations in patients with permanent AF and mitral valve disease that may explain the maintenance of AF despite ablation in these patients.…”

Section: Frequency Mapping To Identify Sources Maintaining Afmentioning

confidence: 99%

Spectral Analysis Identifies Sites of High-Frequency Activity Maintaining Atrial Fibrillation in Humans

et al. 2005

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Background-The identification of sites of dominant activation frequency during atrial fibrillation (AF) in humans and the effect of ablation at these sites have not been reported. Methods and Results-Thirty-two patients undergoing AF ablation (19 paroxysmal, 13 permanent) during ongoing arrhythmia were studied. Electroanatomic mapping was performed, acquiring 126Ϯ13 points per patient throughout both atria and coronary sinus. At each point, 5-second electrograms were obtained to determine the highest-amplitude frequency on spectral analysis and to construct 3D dominant frequency (DF) maps. The temporal stability of the recording interval was confirmed in a subset. Ablation was performed with the operator blinded to the DF maps. The effect of ablation at sites with or without high-frequency DF sites (maximal frequencies surrounded by a decreasing frequency gradient Ն20%) was evaluated by determining the change in AF cycle length (AFCL) and the termination and inducibility of AF. The spatial distribution of the DF sites was different in patients with paroxysmal and permanent AF; paroxysmal AF patients were more likely to harbor the DF site within the pulmonary vein, whereas in permanent AF, atrial DF sites were more prevalent. Ablation at a DF site resulted in significant prolongation of the AFCL (180Ϯ30 to 198Ϯ40 ms; PϽ0.0001; ϭ 0.77), whereas in the absence of a DF site, there was no change in AFCL (169Ϯ22 to 170Ϯ22 ms; Pϭ0.4). AF terminated during ablation in 17 of 19 patients with paroxysmal and 0 of 13 with permanent AF (PϽ0.0001). When 2 patients with nonsustained AF during mapping were excluded, 13 of 15 (87%) had AF termination at DF sites (54% at the initially ablated DF site): 11 pulmonary veins and 2 atrial. In addition, AF could no longer be induced in 69% with termination of AF at a DF site. There were no significant differences in the number or percentage of DF sites detected (5.4Ϯ1.6 versus 4.9Ϯ2.1; Pϭ0.3) and ablated (1.9Ϯ1.0 versus 2.4Ϯ1.0; Pϭ0.3) in those with and without AF termination. The duration of radiofrequency ablation to achieve termination was significantly shorter than that delivered in those with persisting AF (34.8Ϯ24.0 versus 73.5Ϯ22.9 minutes; Pϭ0.0002). All patients with persisting AF had additional DF sites outside the ablated zones. Conclusions-Spectral

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“…6 In the present study, we could only compare the histopathological changes of the LAA with those of the left atrial free wall using samples from the autopsy controls without AF. No significant differences were found between these areas except for endocardial thickening.…”

Section: Causes Of Histopathological Alterations Of the Laa With Valvmentioning

confidence: 99%

“…In addition, patients do not usually require postoperative anticoagulant therapy. 4 The pulmonary veins are believed to be the origin of repetitive activation, 5,6 and the left atrial appendage (LAA) is frequently the source of thrombi for systemic embolism. Therefore, in the maze operative procedure for AF, the pulmonary veins are isolated and the atrial appendages are excised.…”

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confidence: 99%

Histopathological Features of the Resected Left Atrial Appendage as Predictors of Recurrence After Surgery for Atrial Fibrillation in Valvular Heart Disease

Saito

Tamura

Uchida

et al. 2007

Circ J

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Background A histopathological assessment of left atrial appendages (LAA) resected during surgical treatment for atrial fibrillation (AF) was made, with the aim of improving the prediction of postoperative AF recurrence. Methods and ResultsThis clinicopathological study involved 57 surgical cases of valvular AF and 34 ageand sex-matched control autopsy cases with a history of sinus rhythm. LAA from the cases with valvular AF showed greater hypertrophy of cardiomyocytes (p<0.0001), greater nuclear enlargement (p<0.0001), more bizarre nuclei (BN; p<0.0001), and more intercellular fibrosis (ICF; p<0.001). Partial disarray of cardiomyocytes and fatty infiltration were recognized in both the AF and control groups. Thirty-seven cases had maintained sinus rhythm after surgery from 7 months to 10 years. AF recurred within a month of surgery in 17 and after a month in 3; there was no significant difference in histopathological features between them. These 20 cases had more cellular hypertrophy (p<0.025), nuclear enlargement (p<0.025), BN (p<0.01), and ICF (p<0.025) than those who maintained sinus rhythm after surgery. Conclusions The histopathological findings for LAA reflected the underlying valvular diseases; however, the most reliable predictors of postoperative AF recurrence were hypertrophy of cardiomyocytes, bizarre shaped nuclei, and extensive ICF. (Circ J 2007; 71: 70 -78)

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Concurrent multiple left atrial focal activations with fibrillatory conduction and right atrial focal or reentrant activation as the mechanism in atrial fibrillation

Cited by 110 publications

References 19 publications

Transmural Conduction Is the Predominant Mechanism of Breakthrough During Atrial Fibrillation

Transmural Conduction Is the Predominant Mechanism of Breakthrough During Atrial Fibrillation

Spectral Analysis Identifies Sites of High-Frequency Activity Maintaining Atrial Fibrillation in Humans

Histopathological Features of the Resected Left Atrial Appendage as Predictors of Recurrence After Surgery for Atrial Fibrillation in Valvular Heart Disease

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