Ablation procedure
A 4-mm-tip open-irrigated ablation catheter with three 1-mm
minielectodes located laterally at the tip (IntellaNav MiFi
OI®; Boston Scientific) was used. The catheter can
measure real-time LI calculated from a local electric field generated at
the tip of the ablation catheter. During the procedure, the operators
were blinded to LI measurements.
Circumferential ablation around an ipsilateral PV was performed using a
point-by-point technique. Radiofrequency energy was applied for
> 20 sec at each site using a maximum temperature of 42 °C
and maximum power of 35 W. The irrigation rate was 17 mL/min. RFA was
stopped when the catheter moved, esophageal temperature rose to 40 °C,
or bradycardia was induced. The ablation point was marked with a
4-mm-diameter point tag. After completing a >20-sec RFA,
the catheter tip was moved to the next ablation point, located
approximately 4.0 mm from the adjacent point (Figure 1).
After completing circumferential PV ablation, left and right ipsilateral
PV were mapped using the basket catheter, and electrical conduction
inside the ipsilateral PV was analyzed. If left atrium to PV conduction
was present, RFAs targeting conduction gaps on the circumferential line
were delivered until left atrium to PV conduction was
eliminated.9 Creation of sufficient ablation lesions
was assessed by the absence of a conduction gap.