This Article Figures Only Full Text Full Text (PDF) Correction (v39,p1409) 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 Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wu, T.-J. Articles by Chen, P.-S. Search for Related Content PubMed PubMed Citation Articles by Wu, T.-J. Articles by Chen, P.-S.

EXPERIMENTAL STUDY

Progressive action potential duration shortening and the conversion from atrial flutter to atrial fibrillation in the isolated canine right atrium

Tsu-Juey Wu, MD^*,* , Young-Hoon Kim, MD, FACC, Masaaki Yashima, MD, Charles A. Athill, MD, Chih-Tai Ting, MD, PhD^*, Hrayr S. Karagueuzian, PhD, FACC and Peng-Sheng Chen, MD, FACC

^* Division of Cardiology, Department of Medicine, Taichung Veterans General Hospital and Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine, Taipei, Taiwan
Division of Cardiology, Department of Medicine, Cedars-Sinai Medical Center and University of California at Los Angeles School of Medicine, Los Angeles, California, USA

Manuscript received December 27, 2000; revised manuscript received May 25, 2001, accepted August 10, 2001.

^* Reprint requests and correspondence: Dr. Tsu-Juey Wu, Division of Cardiology, Department of Medicine, Taichung Veterans General Hospital, 160, Section 3, Chung-Kang Road, Taichung, Taiwan
tjwu{at}vghtc.vghtc.gov.tw

OBJECTIVES

We sought to evaluate the effects of progressive shortening of the action potential duration (APD) on atrial wave front stability.

BACKGROUND

The mechanisms of conversion from atrial flutter to atrial fibrillation (AF) are unclear.

METHODS

Isolated canine right atria were perfused with 1 to 5 µmol/l of acetylcholine (ACh). We mapped the endocardium by using 477 bipolar electrodes and simultaneously recorded transmembrane potentials from the epicardium. The APD₉₀ was measured during regular pacing (S₁) with cycle lengths of 300 ms. Atrial arrhythmia was induced by a premature stimulus (S₂).

RESULTS

At baseline, only short runs of repetitive beats (<10 cycles) were induced. After shortening the APD₉₀ from 124 ± 15 ms to 72 ± 9 ms (p < 0.01) with 1 to 2.5 µmol/l of ACh, S₂ pacing induced single, stable and stationary re-entrant wave fronts (307 ± 277 cycles). They either anchored to pectinate muscles (5 tissues) or used pectinate muscles as part of the re-entry (4 tissues). When ACh was raised to 2.5 to 5 µmol/l, the APD₉₀ was further shortened to 40 ± 12 ms (p < 0.01); S₂ pacing induced in vitro AF by two different mechanisms. In most episodes (n = 13), AF was characterized by rapid, nonstationary re-entry and multiple wave breaks. In three episodes with APD₉₀ <30 ms, AF was characterized by rapid, multiple, asynchronous, but stationary wave fronts.

CONCLUSIONS

Progressive APD shortening modulates atrial wave front stability and converts atrial flutter to AF by two mechanisms: 1) detachment of stationary re-entry from the pectinate muscle and the generation of multiple wave breaks; and 2) formation of multiple, isolated, stationary wave fronts with different activation cycle lengths.

Abbreviations and Acronyms   ACh = acetylcholine   AF = atrial fibrillation   APD = action potential duration   CV = conduction velocity   ECG = electrocardiogram   RCA = right coronary artery   TMP = transmembrane potential

This article has been cited by other articles:

				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]

				R. Zou, J. Kneller, L. J. Leon, and S. Nattel Substrate size as a determinant of fibrillatory activity maintenance in a mathematical model of canine atrium Am J Physiol Heart Circ Physiol, September 1, 2005; 289(3): H1002 - H1012. [Abstract] [Full Text] [PDF]