Published Online
on September 23, 2002

A more recent version of this article appeared on October 8, 2002

This Article Full Text (PDF) All Versions of this Article: 106/15/1968    most recent 01.CIR.0000037062.35762.B4v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Narayan, S. M. Articles by Franz, M. R. Search for Related Content PubMed PubMed Citation Articles by Narayan, S. M. Articles by Franz, M. R. Related Collections Arrhythmias, clinical electrophysiology, drugs Cardiac development

Submitted on June 4, 2002
Revised on July 25, 2002
Accepted on July 26, 2002

Alternans of Atrial Action Potentials During Atrial Flutter as a Precursor to Atrial Fibrillation

Sanjiv M. Narayan MB, MD, MRCP, Frank Bode MD, Pamela L. Karasik MD, and Michael R. Franz MD, PhD^*

From the University of California and Veterans Affairs Medical Center, San Diego, Calif (S.M.N.), and Georgetown University and Veterans Affairs Medical Center, Washington, DC (F.B., P.K., M.R.F.).

^* To whom correspondence should be addressed. E-mail: mfranz{at}washington.va.gov.

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.

Key words: alternans • atrial flutter • fibrillation • action potentials • waves

This article has been cited by other articles:

				E. Pruvot, F. Jousset, P. Ruchat, J.-M. Vesin, Y. Prudat, T. Zerm, and M. Fromer Propagation velocity kinetics and repolarization alternans in a free-behaving sheep model of pacing-induced atrial fibrillation Europace, November 1, 2007; 9(suppl_6): vi83 - vi88. [Abstract] [Full Text] [PDF]

				S. M. Narayan and M. R. Franz Quantifying fractionation and rate in human atrial fibrillation using monophasic action potentials: implications for substrate mapping Europace, November 1, 2007; 9(suppl_6): vi89 - vi95. [Abstract] [Full Text] [PDF]

				S.-L. Chang, C.-T. Tai, Y.-J. Lin, W. Wongcharoen, L.-W. Lo, K.-T. Lee, S.-H. Chang, T.-C. Tuan, Y.-J. Chen, M.-H. Hsieh, et al. The Role of Left Atrial Muscular Bundles in Catheter Ablation of Atrial Fibrillation J. Am. Coll. Cardiol., September 4, 2007; 50(10): 964 - 973. [Abstract] [Full Text] [PDF]

				Y. Gong, F. Xie, K. M. Stein, A. Garfinkel, C. A. Culianu, B. B. Lerman, and D. J. Christini Mechanism Underlying Initiation of Paroxysmal Atrial Flutter/Atrial Fibrillation by Ectopic Foci: A Simulation Study Circulation, April 24, 2007; 115(16): 2094 - 2102. [Abstract] [Full Text] [PDF]

				P. Coutu, D. Chartier, and S. Nattel Comparison of Ca2+-handling properties of canine pulmonary vein and left atrial cardiomyocytes Am J Physiol Heart Circ Physiol, November 1, 2006; 291(5): H2290 - H2300. [Abstract] [Full Text] [PDF]

				S. M. Narayan T-Wave Alternans and the Susceptibility to Ventricular Arrhythmias J. Am. Coll. Cardiol., January 17, 2006; 47(2): 269 - 281. [Abstract] [Full Text] [PDF]

				B. L. Hoppe, A. M. Kahn, G. K. Feld, A. Hassankhani, and S. M. Narayan Separating Atrial Flutter From Atrial Fibrillation With Apparent Electrocardiographic Organization Using Dominant and Narrow F-Wave Spectra J. Am. Coll. Cardiol., December 6, 2005; 46(11): 2079 - 2087. [Abstract] [Full Text] [PDF]

				C. Scharf, S. Veerareddy, M. Ozaydin, A. Chugh, B. Hall, P. Cheung, E. Good, F. Pelosi Jr, F. Morady, and H. Oral Clinical significance of inducible atrial flutter during pulmonary vein isolation in patients with atrial fibrillation J. Am. Coll. Cardiol., June 2, 2004; 43(11): 2057 - 2062. [Abstract] [Full Text] [PDF]