Europace Advance Access originally published online on August 14, 2009
Europace 2009 11(11):1546-1548; doi:10.1093/europace/eup221
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Voltage analysis after multi-electrode ablation with duty-cycled bipolar and unipolar radiofrequency energy: a case report
Lucas Boersma*,
Anton Mulder,
Ward Jansen,
Eric Wever and
Maurits Wijffels
Cardiology Department, St Antonius Hospital Nieuwegein, PO Box 2500, 3430 EM Nieuwegein, The Netherlands
Manuscript submitted 23 March 2009. Accepted after revision 19 July 2009.
* Corresponding author. Tel: +31 30 609 9111, Fax: +30 30 609 2274, Email: l.boersma{at}antonius.net
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Abstract
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Pulmonary vein ablation with a single-tip catheter remains long
and complex. We describe a typical case of a novel efficient
technique with a decapolar ring catheter utilizing alternating
unipolar/bipolar radiofrequency energy. Voltage analysis and
electrical mapping demonstrate the potential for antrum ablation
and pulmonary vein isolation.
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Introduction
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Pulmonary vein (PV) isolation remains the cornerstone of ablation
for atrial fibrillation.
1
Procedures using single-tip catheters
are long and require additional techniques like three dimensional
(3D) mapping systems and intracardiac echo imaging.
2–4 Recently, a quick and efficient novel ablation technology has
been introduced that uses multi-electrode catheters and alternating
unipolar and bipolar radiofrequency (RF) energy at a maximum
power of 10 W.
5 This report provides a typical example showing
the potential for antrum ablation and PV isolation.
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Description of the pulmonary vein ablation catheter ablation technique
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Details of the ablation system have been described previously.
5 Briefly, a quadripolar catheter is placed in the coronary sinus
(CS) for pacing. A 9.5F inner lumen diameter sheath (Channel,
Bard or Frontier Advance) is introduced, and selective biplane
PV angiography is performed. The decapolar PV ablation catheter
(PVAC) is deployed in the antrum with the guidewire inside the
PV (
Figure 1). Clockwise and counter-clockwise rotation
may increase or decrease the 25 mm diameter of the circle, and
the tip can be extended to adapt to PV anatomy. Multiple applications
(60 s, target temperature 60°C) are then performed for each
vein until the local electrical activity within the antrum has
disappeared. The default setting with the PVAC uses a 4:1 ratio
RF duty-cycle resulting in 80% bipolar and 20% unipolar energy
with a maximum power of 8 W. Bipolar current flows between adjacent
electrodes of all pairs that are selected for energy delivery,
except for electrodes 1 and 10. After ablation, the PVAC is
introduced for mapping inside the vein, and isolation can then
be verified with pacing from the CS or inside the vein. In the
present case, a 15 mm diameter decapolar LASSO mapping catheter
(Biosense-Webster) and a 3D imaging system (Endocardial Solutions,
St Jude, USA) were used to construct a complete 3D cast and
voltage map of the LA (298 points) and demonstrate the effect
of PVAC ablation. During SR, there is a high voltage of 2 mV
and more at the anterior and posterior LA and PVs (
Figure 2,
left maps). The voltage maps on the right after PVAC ablation
were obtained in the same way with special attention for the
PVs (198 points) and clearly show that the LA body voltage remained
unchanged, whereas the PVs are completely devoid of electrical
activity with a sharp demarcation. The electrical silence clearly
extends very far into the antrum, especially for the right-sided
PVs. The PVAC was also used to map the local PV and antrum potentials
to verify isolation.
Figure 3 shows the electrograms before
(pre-PVAC) and after (post-PVAC) ablation in the LSPV. After
PVAC ablation, there is only a far-field component during CS
pacing, and isolated ectopy inside the vein. The complete isolation
was also confirmed by LASSO recording in all veins. The total
procedure time including 3D imaging and LASSO mapping was 89
min with fluoroscopy time of 21 min.
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Figure 3 ECG leads I–III and V1 electrogram recordings from the CS and PVAC. Pre-PVAC shows the five bipolar PVAC recordings with local potentials in the LSPV before ablation is switched on. Post-PVAC shows the same PVAC recordings after ablation, demonstrating absence of PV capture during CS pacing, and electrical isolation with inability of ectopy inside the LSPV to capture the atrium.
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Discussion
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The present case demonstrates that PV isolation with multi-electrode
PVAC ablation is feasible and efficient. The use of 3D imaging
and LASSO mapping in this case, elegantly shows that the ablation
effect of the PVAC extends far away from the ostium into the
PV antrum. Although voltage analysis can never be 100% accurate,
the reduction after ablation is striking, and the LASSO mapping
confirmed isolation in all veins. This seems very similar to
the endpoint of single-tip wide area circumferential ablation
and is not merely a segmental, ostial isolation. More elaborate
studies are needed to quantify and compare this effect in larger
patient groups. The technique will need more validation in challenging
variations of PV anatomy and may depend on patient selection.
Together with long-term follow-up of clinical efficacy such
factors will determine the value of this new ablation system.
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Acknowledgements
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We would like to thank Harry van Wessel for preparation of
Figure 2.
Conflict of interest: L.B. was a former stockholder and consultant of Ablation Frontiers Inc., and is on the speaker bureau and a clinical trainer for Medtronic. L.B. and M.W. have received grant money for performing research for Ablation Frontiers Inc.
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References
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[1] Calkins H, Brugada J, Packer DL, Cappato R, Chen S, Crijns H, et al, with European Heart Rhythm Association (EHRA), European Cardiac Arrhythmia Society (ECAS), American College of Cardiology (ACC), American Heart Association (AHA), Society of Thoracic Surgeons (STS). HRS/EHRA/ECAS Expert Consensus Statement on catheter and surgical ablation of atrial fibrillation: recommendations for personnel, policy, procedures and follow-up. A report of the Heart Rhythm Society (HRS) Task Force on catheter and surgical ablation of atrial fibrillation. Heart Rhythm (2007) 4:816–61.
[CrossRef][Web of Science][Medline][2] Cheema A, Dong J, Dalal D, Marine E, Henrikson C, Spragg D, et al. Long-term safety and efficacy of circumferential ablation with pulmonary vein isolation. J Cardiovasc Electrophysiol (2006) 17:1080–5.[Medline]
[3] Verma A, Patel D, Famy T, Martin T, Burkhardt J, Elayi S, et al. Efficacy of adjuvant anterior left atrial ablation during intracardiac echocardiography-guided pulmonary vein antrum isolation for atrial fibrillation. J Cardiovasc Electrophysiol (2007) 18:151–6.[CrossRef][Web of Science][Medline]
[4] Karch MR, Zrenner B, Deisenhofer I, Schreieck J, Ndrepepa G, Dong J, et al. Freedom from atrial tachyarrhythmias after catheter ablation of atrial fibrillation: a randomized comparison between 2 current ablation strategies. Circulation (2005) 111:2875–80.[Abstract/Free Full Text]
[5] Boersma L, Wijffels M, Oral H, Wever E, Morady F. Pulmonary vein isolation by duty-cycled bipolar and unipolar radiofrequency energy with a multi-electrode ablation catheter. Heart Rhythm J (2008) 5:1635–42.[CrossRef]
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