2.1 | Ablation procedure
Prior to the ablation procedure, cardiac computed tomography and
transesophageal echocardiography were performed in all patients to
define left atrial anatomy, and to rule out intracardiac thrombus. After
obtaining venous access, a steerable, decapolar catheter (Dynamic XT,
Boston Scientific, Marlborough, MA) was positioned within the CS. Left
atrial access was gained by transseptal puncture or via a patent foramen
ovale. Heparin was administered to achieve an activated clotting time of
more than 350 seconds. An electroanatomical 3D mapping system (CARTO 3,
Biosense Webster, Diamond Bar, CA) was used in all cases and left atrial
geometry reconstructed with a multipolar mapping catheter (Pentaray,
Biosense Webster, Diamond Bar, CA). Left atrial voltage maps were
generated before and after VOM-EI and low-voltage area was defined as
bipolar voltage amplitude below 0.5 mV (Figure 1). Radiofrequency
ablation of the mitral isthmus was performed endocardially and from
within the CS as necessary to achieve bi-directional block.
For ablation, an irrigatedātip ablation catheter (ThermoCool SmartTouch
SF, Biosense Webster, Diamond Bar, CA) was used with a power of 20-25 W
in the CS and 35 W in the atrium. Bi-directional block was confirmed by
differential pacing on both sides of the mitral isthmus according to
standard criteria.1 Radiofrequency ablation of targets
other than the mitral isthmus was performed at the discretion of the
operator and as mandated by the clinical situation.