Catheter ablation procedure
Electrophysiological studies and catheter ablation were performed by
experienced operators under intravenous sedation with propofol or
dexmedetomidine. Electroanatomical mapping system (Carto 3, [Biosense
Webster, Inc., Diamond Bar CA, USA]; Ensite NavX, [Abbott, Abbott
Park IL, USA]; or Rhythmia, [Boston Scientific, Boston MA, USA])
were used. Radiofrequency catheter ablation was performed in all cases
from October 2014 to March 2016. From March 2016 to December 2018
cryoballoon ablation was performed for paroxysmal AF and for persistent
AF in patients considered frail and at high risk of procedure-related
complications. Patients with common PVs or a large PV diameter underwent
radiofrequency catheter ablation. Five patients with paroxysmal AF
underwent laser balloon ablation from July 2018 to September 2018.
In general, Ringer’s acetate was used as a peri-procedural infusion.
Infusion volume before the procedure was 0.45 L, infusion volume during
the procedure was 0.1 L/h and infusion volume after the procedure was 1
L. Peri-procedural infusion was reduced or avoided if hydration was
contraindicated, such as in hemodialysis patients, or in other
situations as per the operator’s judgment.
In radiofrequency catheter ablation, circumferential ablation around
both ipsilateral PVs was performed using an open-irrigated linear
ablation catheter via a Swartz Braided SL0 Transseptal Guiding
Introducer Sheath (Abbott) or AGILIS™ NXT Steerable Introducer (Abbott).
PV isolation was considered complete when the 20-pole circular catheter
no longer recorded any PV potentials.
In cryoballoon ablation, an Arctic Front Advance cryoballoon catheter
with a 28-mm balloon size (Medtronic, Inc., Minneapolis MN, USA) was
passed into each PV under guidance by fluoroscopy and/or a
electroanatomical mapping system. After confirming PV occlusion by
pulmonary venography, cryoablation commenced and was usually continued
for 180 seconds. If left atrium-PV conduction persisted after
cryoballoon ablation, an additional touch-up ablation was performed
using an open-irrigated linear ablation catheter with a 3.5-mm tip.
Additional ablation was also performed for any AF triggers originating
from non-PV foci induced by isoproterenol infusion, and for spontaneous
atrial flutter or atrial tachycardia induced by atrial burst stimuli.
Empirical ablation, such as left atrial linear ablation, complex
fractionated atrial electrogram ablation, or low-voltage-area (LVA)
ablation was also performed according to the operator’s judgment.
Following PV isolation, voltage mapping was performed using a
multi-electrode mapping catheter or bipolar 3.5-mm tip catheter during
sinus rhythm or with pacing from the right atrium. The presence of LVAs
was defined as areas with voltage < 0.5 mV covering ≥ 5
cm2 across the total surface area of the left atrium.
Thermocool SmartTouch (Biosense Webster), Thermocool SmartTouch SF
(Biosense Webster), NAVISTAR Thermocool (Biosense Webster), Thermocool
SF (Biosense Webster), CELSIUS (Biosense Webster), TactiCath SE
(Abbott), or FlexAbility (Abbott) were used for open-irrigated linear
ablation catheters. RF energy was applied for 30 s at each site using a
maximum temperature of 42°C and maximum power of 35 W. An irrigation
flow rate of 17 mL/min was used with Thermocool SmartTouch, NAVISTAR
Thermocool, or TactiCath SE catheters; 8 mL/min was used with the other
catheters.