Alternans of atrial action potentials during atrial flutter as a precursor to atrial fibrillation
Document Type
Journal Article
Publication Date
10-8-2002
Journal
Circulation
Volume
106
Issue
15
DOI
10.1161/01.CIR.0000037062.35762.B4
Keywords
Action potentials; Alternans; Atrial flutter; Fibrillation; Waves
Abstract
Background - The mechanisms underlying the transition of typical atrial flutter (Afl) to fibrillation (AF) remain unclear. We set out to test the hypothesis that Afl disorganizes to AF via alternans of atrial action potentials. Methods and Results - In 38 patients with Afl, monophasic action potentials (MAPs) were recorded at the isthmus and either high or low right atrium (HRA, LRA) during overdrive pacing to 160 ms or to the initiation of AF, whichever came first. MAP duration measured at 90% repolarization was longer at the isthmus in all patients, and failed to shorten with rate, compared with the HRA (n=38) or LRA (n=5). In 20 patients who developed AF, progressive pacing first caused alternans of isthmus MAP duration and amplitude at mean cycle length of 219±45 ms, followed by AF at a mean onset cycle length of 184±38 ms. Subsets of this group showed spontaneous action potential duration alternans at the isthmus (11 of 20 patients) and 2:1 isthmus conduction block immediately preceding AF (4 of 20 patients). In the 18 patients who did not develop AF, MAP alternans was less common (9 of 18 patients; P<0.0003), and occurred only at faster pacing (cycle length = 169±25 ms; P<0.05). Conclusions - In patients with typical Afl, action potential duration rate maladaptation at the isthmus may lead to action potential duration alternans and conduction block preceding the transition to AF. These isthmus characteristics may enable the spontaneous initiation of AF through wavefront fractionation and may explain the benefits of isthmus ablation in preventing AF recurrence.
APA Citation
Narayan, S., Bode, F., Karasik, P., & Franz, M. (2002). Alternans of atrial action potentials during atrial flutter as a precursor to atrial fibrillation. Circulation, 106 (15). http://dx.doi.org/10.1161/01.CIR.0000037062.35762.B4