2.4 Mapping and ablation procedure
Transesophageal echocardiography was performed before the procedure in
all patients to exclude any thrombus formation. The patients were
studied under moderate to deep sedation while breathing spontaneously.
Standard electrode catheters were placed in the right ventricular apex
and coronary sinus after which a single transseptal puncture was
performed. Unfractionated heparin was administered in a bolus form
before the transseptal puncture to maintain an activated clotting time
of more than 300 seconds. Mapping and ablation were performed using the
NavX system (Abbott, Chicago, IL) as a guide after integration of a 3D
model of the anatomy of the LA and PVs obtained from the MRI. A 20-pole
circular mapping catheter (OptimaTM or Reflexion
HDTM, Abbott) and ablation catheter-reconstructed LA
posterior anatomy was aligned with the MRI.8Subsequently, a phase mapping using the ExTRa Mapping and complex
fractionated atrial electrogram (CFAE) mapping using the NavX system
were performed simultaneously. As for the CFAE mapping, a definition of
the excitation cycle length of below 120 ms was
employed.9