Electrophysiology and Mapping Procedure
Details of intracardiac access have been previously
described.11 Antiarrhythmic drugs were discontinued at
≥ 5 half-lives before ablation. A 20-pole electrode catheter was placed
in the high right atrium and coronary sinus vein. A 20-pole high-density
mapping catheter (PentaRay, Biosense Webster, interelectrode spacing:
2-6-2 mm) were placed into the LA with the assistance of a steerable
sheath (Agilis, St Jude Medical).
The surface electrocardiogram and intracardiac electrograms were
recorded using a computer-based digital recording system (Claris, St
Jude Medical). Intracardiac electrograms were filtered at 30 to 500 Hz
and exported for offline analysis. All procedures were performed with a
3-dimentional mapping, CARTO®3 version 7 system
(Biosense Webster Inc., Diamond Bar, CA, USA). After creating the LA
geometry using fast anatomical mapping, the PentaRay catheter was
positioned sequentially at the various sites of the LA to create a
CARTFINDER map using 30-second unipolar signals in all electrodes with
reference to Wilson’s Central Terminal filtered between 0.05 and 500 Hz.
We did not attempt to map inside the pulmonary veins (PVs) and deep
inside of the left atrial appendage (LAA) due to the potential
difficulty in deploying the PentaRay catheter on the surface of those
regions. Bipolar signals for each recording point were obtained
simultaneously during CARTOFINDER mapping. The low voltage areas (LVA)
were defined as the sites of bipolar voltage amplitude (< 0.5
mV) during AF.12 We also performed high-density
bipolar electrogram mapping to identify the fractionated electrogram
area using the interval confidence level mapping mode (ICL mode) on the
CARTO system. The fractionated electrogram area was defined as ≥ 60% of
the maximum value of the ICL.13