Ablation:
Ablation was performed using a “point by point” technique. Settings
were: catheter irrigation-flow rate of 18 mL/min, target temperature 45°
and maximal energy of 50 W. During the ablation we aimed to achieve a
contact force of 10 to 20 grams at all times. Radiofrequency energy (RF)
was applied at each ablation site using the automated lesion tagging
ablation-index module (Biosense Webster) to mark the location and
efficacy of each lesion. The ablation-index settings were: catheter
stability position minimum-time of 5 seconds, and maximum range 3-4 mm,
minimum force 3 g, (the blue and yellow marks give two different contact
force values) and lesion tag of 3 mm. The maximal RF time at each
ablation site was 10 seconds for the posterior wall and 25 seconds for
the anterior quadrants. We aimed for an ablation-index value of 400 for
the back wall and 500 for the anterior quadrants. Upon completion of the
wide antral circumferential ablation (WACA), the ablation catheter was
withdrawn from the left atrium and replaced by a lasso circular mapping
catheter (Lasso, Biosense Webster, Inc). The acute end-point of the
procedure was PV isolation demonstrated by disappearance of local PV
electrograms and confirmed by standard pacing maneuvers, to confirm
entrance and exit block, with a lasso circular mapping catheter. In case
of lack of first pass isolation the residual PV-LA connections were
tagged on the CARTO system and additional RF was delivered until PV
isolation was achieved. After a waiting period of 20 minutes, each
pulmonary vein was assessed for entrance and exit block. Each vein was
also assessed for the presence of dormant pulmonary vein-left atrium
connection with intravenous adenosine 18 mg injection. Patients with
evidence of dormant connections revealed by adenosine challenge,
received additional ablations according to the mapping catheter until
the connections were completely abolished.