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How to perform pulmonary vein isolation for the treatment of atrial fibrillation: use of the LocaLisa catheter navigation system
Department of Cardiology, Academic Medical Centre P.O. Box 22660, 1100 DD Amsterdam, The Netherlands
Manuscript submitted 29 July 2003. Accepted after revision 30 November 2003.
*Corresponding author. Tel.: +31-20-566-9111; fax: +31-20-691-4940. E-mail address: t.a.simmers{at}amc.uva.nl (T.A. Simmers).
Key Words: atrial fibrillation, catheter ablation, pulmonary veins, mapping
Atrial fibrillation (AF) is the most prevalent supraventricular arrhythmia in man; its treatment is a major challenge to clinicians. The concept of focally induced AF due to ectopy from the pulmonary veins (PV) has revolutionised the approach to non-pharmacological therapy [1]
. Prospective studies and reliable markers for the identification of patients most likely to benefit are lacking; in particular, it is unclear how many patients with paroxysmal AF actually have a (PV-related) focal mechanism. Short-term results of pulmonary vein isolation (PVI) in selected groups of patients are, however, highly promising. Conceptually speaking, the approach to PVI can be divided into two schools. In the more focus-driven/segmental method according to Haïssaguerre et al., radiofrequency (RF) lesions are applied slightly distal to the PV ostia to induce electrical isolation of the muscular sleeves of the PV (and associated arrhythmogenic foci) from the left atrium [2]. This method has since evolved to entail lesions just outside the PV ostia, and include additional lines of block between the left inferior PV and mitral annulus, and between the two superior PVs. This in effect brings it closer to Pappone et al.'s approach (described below) than the original ectopy-driven approach first described by Haïssaguerre et al. All four veins are generally targeted. In most cases, segmental ablation induces total electrical isolation, obviating the need for circumferential ablation. This may conceivably reduce the risk of PV stenosis, one of the most serious complications reported following PVI, while lowering the number of RF deliveries and screening time. In the approach according to Pappone et al. [3], reminiscent of the surgical Maze procedure, the left and right PV ostia are circumferentially isolated from the left atrium en bloc, and the left circle connected with the mitral annulus. Reduction of bipolar electrograms to 0.1 mV or less within the lesion and more than 30 ms delay in activation timing either side of the line of conduction block were reported end-points. In either method, meticulous catheter positioning relative to the PV ostia and creation of contiguous lines or areas of lesion are of utmost importance. The LocaLisa system (Medtronic, Minneapolis, MN) has been previously described [4], and its use in catheter navigation and ablation for a variety of indications has been demonstrated. The system allows real-time three-dimensional visualisation of catheter position, including the Lasso catheter (Biosense Webster, Diamond Bar, CA) used to record PV potentials at the ostium during PVI, reducing fluoroscopy time [5]. The following case demonstrates the use of the LocaLisa system in RF ablation for PVI in the treatment of paroxysmal AF.
The patient, an otherwise healthy 35-year-old male, was referred with frequent paroxysms of therapy refractory AF, generally exercise-related. He had a structurally normal heart at both cardiac ultrasonography and MRI. Electrophysiological study and PVI were undertaken, with the patient still on sotalol. Multielectrode catheters were advanced from the right femoral vein under fluoroscopic guidance to the right ventricle and coronary sinus; two additional catheters were introduced into the left atrium via an open foramen ovale: a Lasso and a Conductr mapping catheter (Medtronic, Minneapolis, MN). Fig. 1 demonstrates the use of the LocaLisa to define anatomic landmarks. As the left upper PV is the most frequent focus of arrhythmogenic PV ectopy [2], the Lasso catheter was positioned at this ostium following identification by cineangiography. Each PV was mapped using LocaLisa (Fig. 2). In this fashion, orientation of the veins and location of the ostia were marked for future reference during the procedure. No spontaneous PV ectopy or PV potentials were apparent at baseline; however, during isoprenaline infusion conduction was seen to arise between the left atrium and the left upper PV. Earliest PV activation both during spontaneous rhythm and coronary sinus pacing was at Lasso electrode 4 (Fig. 3). The mapping catheter was positioned at this site and a single 60 s 35 W RF pulse was delivered. PV potentials vanished during ablation (Fig. 4). Based on local activation time during coronary sinus pacing of recurrent, residual PV potentials shortly after the first RF pulse, a second pulse was delivered at the adjacent Lasso electrode (#5), resulting in persistent electrical isolation of the left upper PV. No PV ectopy or tachycardia induced either by atrial stimulation (single extrastimulus) or isoprenaline infusion was observed, so it was decided to evaluate the clinical effect of this approach during follow-up. Four months later, the patient is not on antiarrhythmic drugs, and remains free of symptomatic AF recurrence.
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This case demonstrates PVI using segmental ablation, and the use of the LocaLisa system to achieve this goal. This non-fluoroscopic navigation and mapping system facilitates PVI by tagging anatomic landmarks and ablation sites in the same image as the moving catheter, and allowing reduction of screening time. It should be stressed that it is unusual for PV ectopy to arise from only one vein, or isolation of a single vein to have such a degree of clinical success. It is even more unusual to achieve PV isolation with as little RF delivery in comparison with other reports. Prospective study may indicate whether this reflects a beneficial effect of the LocaLisa system in guiding RF delivery.
References
[1] Jaïs P., Haïssaguerre M., Shah D.C., Chouairi S., Gencel L., Hocini M., et al. A focal source of atrial fibrillation treated by discrete radiofrequency ablation. Circulation 1997; 95: 572–576.
[2] Haïssaguerre M., Jaïs P., Shah D.C., Takahashi A., Hocini M., Quiniou G., et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med 1998; 339: 659–666.
[3] Pappone C., Rosanio S., Oreto G., Tocchi M., Gugliotta F., Vicedomini G., et al. Circumferential radiofrequency ablation of pulmonary vein ostia: a new anatomic approach for curing atrial fibrillation. Circulation 2000; 102: 2619–2628.
[4] Wittkampf F.H.M., Wever E.F.D., Derksen R., Wilde A.A.M., Ramanna H., Hauer R.N.W., et al. LocaLisa: new technique for real-time 3-dimensional localization of regular intracardiac electrodes. Circulation 1999; 99: 1312–1317.
[5] Kirchhof P., Loh P., Eckardt L., Ribbing M., Rolf S., Eick O., et al. A novel nonfluoroscopic catheter visualization system (LocaLisa) to reduce radiation exposure during catheter ablation of supraventricular tachycardias. Am J Cardiol 2002; 90: 340–343.[CrossRef][Web of Science][Medline]
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