GP mapping and ablation in the left atrium and AF ablation
We performed endocardial electroanatomic mapping of the left atria (LA) for anatomic geometry reconstruction with NAVx Ensite Precision® (Abbot Inc.) or Carto3 system® (Biosense Webster Inc.) using a bidirectional irrigated catheter with 4mm (FlexAbility®, Abbot Inc), a 3.5mm (ThermoCool SmartTouch® or Navistar RMT ThermoCool®, Biosense Webster Inc.) or a circular mapping catheter in patients who underwent atrial fibrillation ablation (Advisor®, Abbot Inc and LASSO® Biosense Webster, Inc.). We started the procedure by mapping in the LA after transseptal puncture with a Brockenbrough® needle (Medtronic Inc.) under fluoroscopic guidance. After the puncture a bolus o 10 000 IU of heparin was administrated and targeted activated clot time (ACT) was maintained between 300-400 seconds and monitored every 30 minutes after achieving a value of 300 seconds. We identified the pulmonary vein (PV) ostia, left atrial appendage and mitral valve annulus. In the reconstructed anatomy, we marked the empiric anatomic location of the atrial right GP site as previously described in the literature(1,4,5,9,11)(Figure 1). The anterior right GP in the common vestibulum of the anterior aspect of the right pulmonary veins and the inferior right GP in the inferior aspect of the inferior pulmonary vein).
For ablation of the GP, we used only an anatomical approach aiming at previously described empiric GP sites. Radiofrequency (RF) lesions were performed for 30 seconds with 25W (20W in the inferior aspect of the right inferior pulmonary vein) with a set temperature of 43ºC, approximately, 10mm from the respective PV in a cloud-like shape. The endpoint of the ablation was the deployment of lesions in all pre-specified ablation targets, irrespective of any change in RR interval or Wenckebach Cycle Length (WBCL).
For patients with an indication for AF ablation, the used technique was PV isolation (PVI), with RF circumferential lesions at PV antrum (around 10-15mm from PV ostia) with 20W for 20 seconds in the posterior wall and 25W for 30 seconds in the remaining walls, with a limit temperature of 43ºC and aiming at abolishment of local electrograms to <0,1mV. The endpoint for PV isolation success was the disappearance or dissociation of PV potentials and the achievement of bidirectional block between PV and LA. If necessary, additional RF lesions were made at conduction gap sites.