Europace Advance Access originally published online on February 23, 2007
Europace 2007 9(4):208-211; doi:10.1093/europace/eum014
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ABLATION
Elimination of cavotricuspid isthmus conduction by a single ablation lesion: observations from a maximum voltage-guided ablation technique
Arrhythmia Service, University of Western Ontario, London Health Sciences Centre, 339 Windermere Road, London, Ontario N6A 5A5, Canada
Aims The architecture of the cavotricuspid isthmus has been shown to be highly variable made of a large number of interspersed bundles in the majority. Targeting high-amplitude signals has resulted in short-ablation times, likely due to the selective ablation of such bundles. We report a series of cases where a single site ablation resulted in bidirectional block, supporting the hypothesis that conduction can occur over a discrete portion of the isthmus.
Methods and results Sixty consecutive patients underwent ablation for isthmus-dependent atrial flutter using voltage-guided approach between September 2005 and June 2006. We found in five patients (8.3%) (four male, mean age 58.1 ± 11.4 years), in whom bidirectional block was achieved by ablation at a single site. The isthmus was mapped at the 6 o'clock LAO position, and bipolar amplitude was measured during pull-back to find the site of largest atrial voltage. The atrial and ventricular electrogram (EGM) measured 2.00 ± 1.6 and 0.2 ± 0.1 mV, respectively, at the successful site, resulting in the mean atrium/ventricle ratio of 9.1 ± 4.1. The total radiofrequency time was 83.8 ± 25.3 s, and the procedure time was 68.6 ± 10.4 min, including 30 min waiting time after the procedure. Flutter has not recurred over 5.7 ± 4.0 months follow-up.
Conclusion Targeting the largest atrial EGM in the isthmus can produce bidirectional block with a single site ablation. This supports the hypothesis that trans-isthmus conduction can occur over a discrete part of the isthmus, likely due to the underlying bundle architecture.
Key Words: Atrial flutter, Ablation, Atrial electrogram, Voltage guided, Cavotricuspid isthmus
* Corresponding author. Tel: +1519 663 3746; fax: +1 519 663 3782. E-mail address: allan.skanes{at}lhsc.on.ca
Manuscript submitted 27 September 2006. Accepted after revision 5 January 2007.
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  J.-A. Cabrera, S. Y. Ho, and D. Sanchez-Quintana How anatomy can guide ablation in isthmic atrial flutter Europace, January 1, 2009; 11(1): 4 - 6. [Full Text] [PDF]
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