2.3 Electrophysiologic study with 3D voltage mapping
All antiarrhythmic drugs had been discontinued for at least 5
half-lives, and the electrophysiologic study with voltage mapping was
performed under conscious sedation achieved with dexmedetomidine,
propofol, and fentanyl.8,9 Two long sheaths (an Agilis
steerable sheath and an SL0 sheath; St. Jude Medical Inc., St. Paul, MN,
USA) were positioned in the LA, and LA pressure was measured. An
activated clotting time >300 seconds was maintained during
the procedure by administration of heparin. The study was performed with
use of a 3D mapping system (CARTO 3, Biosense Webster, Diamond Bar, CA,
USA) and a multispline catheter with 2-mm interelectrode spacing
(Pentaray NAV; Biosense Webster).
High-density electroanatomical maps were obtained during sinus rhythm.
If the patient was in AF rhythm, low energy (10–20 joules) intracardiac
cardioversion was performed with use of a BeeAT catheter (Japan
Lifeline, Tokyo, Japan) placed in the coronary sinus. Bipolar signals
were acquired, with a high-pass filter set at 30 Hz and low-pass filter
set at 500 Hz. LVZs were identified as areas with a bipolar peak-to-peak
voltage amplitude of <0.5 mV.4‑7,10,11 In
addition, the ascending aorta was reconstructed by means of the 3D
mapping system and merged with the LA voltage map. The electroanatomical
maps were merged with the CT images that had been obtained.
For the purpose of the study, we measured the LVZs on the anterior LA
wall in the areas of contact between the LA and the ascending aorta and
sinus of Valsalva.