Electrophysiologic efficacy of irrigated bipolar radiofrequency in the clinical setting
Read at the Thirty-fifth Annual Meeting of The Western Thoracic Surgical Association, Banff, Alberta, Canada, June 24–27, 2009.
Received 19 June 2009; received in revised form 7 November 2009; accepted 28 December 2009.
Objective
Clinical success of atrial fibrillation ablation depends on persistent transmurality of the lesions. Although bipolar radiofrequency grants acute pulmonary vein isolation, the fate of such ablations in the clinical setting is unknown. We assessed postoperative pulmonary vein isolation up to 3 weeks after open chest bipolar radiofrequency ablation.
Methods
Thirteen consecutive patients with mitral valve disease (mean age, 60 ± 10 years) and atrial fibrillation undergoing concomitant ablation with the BP2 bipolar device (Medtronic, Inc, Minneapolis, Minn) were enrolled for electrophysiologic assessment. During surgery, pairs of additional temporary wires were positioned on the right pulmonary veins and on the roof of the left atrium before bipolar ablation. Entrance block (abatement or disconnection of electrogram potentials) and exit block (no entrainment during pulmonary vein pacing) of the right pulmonary veins and of the free left atrium were assessed before and after ablation. After right pulmonary vein isolation was obtained, one additional encircling line was added. Electrophysiologic assessment was repeated before discharge and at 3 weeks.
Results
Baseline right pulmonary vein pacing threshold was 2.9 ± 1.6 mA. After 3 ± 1 encircling ablations, bidirectional block was attained in all pulmonary veins. At pre-discharge electrophysiologic study, complete isolation persisted in all cases. At 3 weeks, conduction block persisted in 11 (85%) of 13 patients. All patients were discharged in sinus rhythm. At follow-up (19 ± 7 months), 12 (92%) of 13 patients were still free from atrial fibrillation.
Conclusions
Irrigated bipolar radiofrequency ablation provides acute transmurality after multiple ablations. However, total recovery of conduction occurred in 15% of the patients after 3 weeks. Repeated multiple ablations, possibly complemented by block validation, are suggested to help achieve durable transmurality with such technology.
aDivision of Cardiac Surgery, S Raffaele University Hospital, Milan, Italy
bRehabilitation Unit, S Raffaele University Hospital, Milan, Italy
Address for reprints: Stefano Benussi, MD, PhD, Division of Cardiac Surgery, S Raffaele University Hospital, via Olgettina 60, 20132 Milan, Italy.
Disclosures: Stefano Benussi reports consulting fees from Estech and lecture fees from St. Jude, Atricure, Medtronic, Cryocath, and Edwards. Valerio Cerbi and Ylenia Privitera were supported by a grant from Medtronic.
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