[3-d mapping of pulmonary veins using a multipolar basket catheter. Implications for catheter ablation of atrial fibrillation].

BACKGROUND: Focal discharges from pulmonary veins are the major sources of paroxysmal atrial fibrillation. The aim of this study was to analyze the activation pattern of pulmonary veins during sinus rhythm and ectopy with the help of a multipolar basket catheter and to disconnect them from the left atrium by localized radiofrequency catheter ablation.

PATIENTS AND METHODS: We studied 65 patients (43 male, 22 female, mean age 54 +/- 12 years) with drug-refractory atrial fibrillation (paroxysmal n = 42, persistent n = 23). A 64-pole basket catheter (Figure 1) with a diameter of 31 or 38 mm (Constellation, Boston Scientific) was placed transseptally into the pulmonary veins to record its activation during ectopic beats and during sinus rhythm or coronary sinus pacing (Figure 2). The ablation catheter was placed as ostial as possible next to the electrodes showing the earliest pulmonary vein activation during sinus rhythm or coronary sinus pacing (Figures 3 and 4a). The radiofrequency energy was delivered with a maximum temperature of 50 degrees C and a maximum power of 30 W. In 32 patients, an irrigated-tip catheter (Thermocool, Biosense-Webster) was used. Endpoint of the procedure was the complete elimination of all distal pulmonary vein potentials during sinus rhythm (Figure 4b).

RESULTS: The mean number of procedures per patients was 1.25, mean procedure time 236 +/- 79 min, and mean fluoroscopy time 40 +/- 17 min, respectively. In 16 veins, repetitive discharges (more than three) could be recorded under stable conditions (Figures 2 and 5). In twelve of these 16 pulmonary veins (75%), the activation pattern during ectopic beats was identical in the same vein, but different from one vein to another (Figure 2). In four veins, changing activation patterns were observed in the same vein. Focal atrial fibrillation was recorded in four pulmonary veins (Figures 6 and 7). A total of 187 out of 190 mapped veins were successfully isolated at the ostium by ablating 2.3 +/- 1.1 separated conduction pathways. In 16 patients, a second EP study was performed for recurrence of atrial fibrillation. Recovery of conduction of a previously isolated pulmonary vein was identified as the primary reason for recurrence of atrial fibrillation. The second reason were ostial foci, localized proximal to the ablation line (Figure 8). COMPLICATIONS AND FOLLOW-UP: One pericardial tamponade occurred. Carbonization on the splines of the basket catheter-observed in twelve cases with use of a nonirrigated-tip catheter-was prevented by use of irrigated-tip catheters. At 12 months, 36 out of 65 patients (55%) are in sinus rhythm without antiarrhythmic drug use, 28 of 42 patients (67%) with paroxysmal atrial fibrillation. Only one pulmonary vein stenosis > 50% was detected by angiomagnetic resonance imaging 1 year after the procedure.

CONCLUSION: 75% of the arrhythmogenic pulmonary veins showed a stable and specific pattern during repetitive ectopic activity. Ostial ablation of 2.3 +/- 1.1 separated conduction pathways from the left atrium into the pulmonary veins resulted in complete conduction block in 187 of 190 veins.