Ablation Procedure
All patients underwent the ablation procedure with general anesthesia.
All patients underwent detailed EAM with either CARTO or ESI mapping
systems following vascular and left atrial access prior to and following
ablation. Patients presenting in AF underwent cardioversion to NSR prior
to EAM. All patients underwent PVI as the principle ablative strategy of
the procedure. Additional non-PV targets (linear lesions; low-voltage
areas) were ablated at the operator’s discretion.
Catheter ablation was performed using either an irrigated, contact
force-sensing RF ablation system (Biosense Webster, etc., or Abbot/ESI)
or a cryoballoon ablation catheter (Arctic Front and Arctic Front
Advance, Medtronic Inc.). For patients undergoing RF ablation, target
power delivery to the anterior and posterior LA walls was 35–45 and
25–35 W, respectively. Patients undergoing cryo-balloon ablation
underwent fluoroscopic positioning of a 28- or 23mm cryo-balloon to
achieve complete PV occlusion assessed by contrast injection. A minimum
of two freeze-thaw cycles (3 min duration) were applied to each vein,
sufficient to achieve PV isolation as assessed by a multipolar mapping
catheter.
All patients had an esophageal temperature probe in place during
ablation, with temporary cessation of lesion application if esophageal
temperature deviation occurred. Phrenic nerve pacing was performed
during cryo-balloon ablation in right-sided pulmonary veins in all
cases, with cessation of ablation upon any diminution in the force of
diaphragmatic contraction.
PV isolation was assessed in all cases after a 20-minute waiting period
by demonstrating an entrance block to each vein, assessed during sinus
rhythm on post-ablation EAM. Exit block was demonstrated at the
operator’s discretion, as was occult PV reconnection during adenosine
infusion.