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Long-term frequency gradients during persistent atrial fibrillation in sheep are associated with stable sources in the left atrium.

ABSTRACT: Dominant frequencies (DFs) of activation are higher in the atria of patients with persistent than paroxysmal atrial fibrillation (AF), and left atrial (LA)-to-right atrial (RA) DF gradients have been identified in both. However, whether such gradients are maintained as long-term persistent AF is established remains unexplored. We aimed at determining in vivo the time course in atrial DF values from paroxysmal to persistent AF in sheep and testing the hypothesis that an LA-to-RA DF difference is associated with LA drivers in persistent AF.AF was induced using RA tachypacing (n=8). Electrograms were obtained weekly from an RA lead and an implantable loop recorder implanted near the LA. DFs were determined for 5-second-long electrograms (QRST subtracted) during AF in vivo and in ex vivo optical mapping. Underlying structural changes were compared with weight-matched controls (n=4). After the first AF episode, DF increased gradually during a 2-week period (7±0.21 to 9.92±0.31 Hz; n=6; P<0.05). During 9 to 24 weeks of AF, the DF values on the implantable loop recorder were higher than the RA (10.6±0.08 versus 9.3±0.1 Hz, respectively; n=7; P<0.0001). Subsequent optical mapping confirmed a DF gradient from posterior LA-to-RA (9.1±1.0 to 6.9±0.9 Hz; P<0.05) and demonstrated patterns of activation compatible with drifting rotors in the posterior LA. Persistent AF sheep showed significant enlargement of the posterior LA compared with controls.In the sheep, transition from paroxysmal to persistent AF shows continuous LA-to-RA DF gradients in vivo together with enlargement of the posterior LA, which harbors the highest frequency domains and patterns of activation compatible with drifting rotors.

SUBMITTER: Filgueiras-Rama D

PROVIDER: S-EPMC4121987 | biostudies-literature | 2012 Dec

REPOSITORIES: biostudies-literature

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Long-term frequency gradients during persistent atrial fibrillation in sheep are associated with stable sources in the left atrium.

Filgueiras-Rama David D Price Nicholas F NF Martins Raphael P RP Yamazaki Masatoshi M Avula Uma Mahesh R UM Kaur Kuljeet K Kalifa Jérôme J Ennis Steven R SR Hwang Elliot E Devabhaktuni Vijay V Jalife Jose J Berenfeld Omer O

Circulation. Arrhythmia and electrophysiology 20121010 6

<h4>Background</h4>Dominant frequencies (DFs) of activation are higher in the atria of patients with persistent than paroxysmal atrial fibrillation (AF), and left atrial (LA)-to-right atrial (RA) DF gradients have been identified in both. However, whether such gradients are maintained as long-term persistent AF is established remains unexplored. We aimed at determining in vivo the time course in atrial DF values from paroxysmal to persistent AF in sheep and testing the hypothesis that an LA-to-R ...[more]

PMID: 23051840

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Project description:Background Adenosine shortens action potential duration and refractoriness and provokes atrial fibrillation. This study aimed to evaluate the effect of adenosine on mechanisms of wavefront propagation during atrial fibrillation. Methods and Results The study included 22 patients undergoing catheter ablation for persistent atrial fibrillation. Left atrial mapping was performed using the AcQMap charge density system before and after administration of intravenous adenosine at 1 or more of 3 time points during the procedure (before pulmonary vein isolation, after pulmonary vein isolation, and after nonpulmonary vein isolation ablation). Wave-front propagation patterns were evaluated allowing identification and quantification of localized rotational activation (LRA), localized irregular activation, and focal firing. Additional signal processing was performed to identify phase singularities and calculate global atrial fibrillation cycle length and dominant frequency. A total of 35 paired maps were analyzed. Adenosine shortened mean atrial fibrillation cycle length from 181.7±14.3 to 165.1±16.3, (mean difference 16.6 ms; 95% CI, 11.3-21.9, P<0.0005) and increased dominant frequency from 6.0±0.7 Hz to 6.6±0.8 Hz (95% CI, 0.4-0.9, P<0.0005). This was associated with a 50% increase in the number of LRA occurrences (16.1±7.6-24.2±8.1; mean difference 8.1, 95% CI, 4.1-12, P<0.0005) as well as a 20% increase in the number of phase singularities detected (30.1±7.8-36.6±9.3; mean difference 6.5; 95% CI, 2.6-10.0, P=0.002). The percentage of left atrial surface area with LRA increased with adenosine and 42 of 70 zones (60%) with highest density of LRA coincided with high density LRA zones at baseline with only 28% stable across multiple maps. Conclusions Adenosine accelerates atrial fibrillation and promotes rotational activation patterns with no impact on focal activation. There is little evidence that rotational activation seen with adenosine represents promising targets for ablation aimed at sites of stable arrhythmogenic sources in the left atrium.

Dataset Information

Long-term frequency gradients during persistent atrial fibrillation in sheep are associated with stable sources in the left atrium.

Publications

Long-term frequency gradients during persistent atrial fibrillation in sheep are associated with stable sources in the left atrium.

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