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Europace 2007 9(Supplement 6):vi83-vi88; doi:10.1093/europace/eum211
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© The European Society of Cardiology 2007. All rights reserved. For permissions, please e-mail: journals.permissions@oxfordjournals.org

Propagation velocity kinetics and repolarization alternans in a free-behaving sheep model of pacing-induced atrial fibrillation

Etienne Pruvot1,*, Florian Jousset2, Patrick Ruchat3, Jean-Marc Vesin2, Yann Prudat2, Thomas Zerm1 and Martin Fromer1

1 Service of Cardiology, BH10-982, CHUV, Rue du Bugnon 46M, 1011 Lausanne, Switzerland; 2 Signal Processing Institute, EPFL, 1015 Lausanne, Switzerland; 3 Service of Cardiovascular Surgery, CHUV, 1011 Lausanne, Switzerland

Aims: Experimental models have reported conflicting results regarding the role of dispersion of repolarization in promoting atrial fibrillation (AF). Repolarization alternans, a beat-to-beat alternation in action potential duration, enhances dispersion of repolarization when propagation velocity is involved.

Methods and results: In this work, original electrophysiological parameters were analysed to study AF susceptibility in a chronic sheep model of pacing-induced AF. Two pacemakers were implanted, each with a single right atrial lead. Right atrial depolarization and repolarization waves were documented at 2-week intervals. A significant and gradual decrease in the propagation velocity at all pacing rates and in the right atrial effective refractory period (ERP) was observed during the weeks of burst pacing before sustained AF developed when compared with baseline conditions. Right atrial repolarization alternans was observed, but because of the development of 2/1 atrioventricular block with far-field ventricular interference, its threshold could not be precisely measured. Non-sustained AF was not observed at baseline, but appeared during the electrical remodelling in association with a decrease in both ERP and propagation velocity.

Conclusion: We report here on the feasibility of measuring ERP, atrial repolarization alternans, and propagation velocity kinetics and their potential in predicting susceptibility to AF in a free-behaving model of pacing-induced AF using the standard pacemaker technology.

Key Words: Atrial fibrillation, Repolarization alternans, Remodelling, Pacemaker

* Corresponding author. Tel: +41 21 3140104; fax: +41 21 3140013.E-mail address: etienne.pruvot{at}chuv.ch


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