SVC isolation
Empirical SVC isolations were performed in the first AF ablation
session. The SVC potentials were recorded by a variable 20 polar,
circular mapping catheter (7F Inquiry OptimaTM PLUS
Catheter; Abbott, St Paul, Minnesota, USA) at the level of the lower
border of the right pulmonary artery after SVC venography. The isolation
line was set at the level of the lower border of the right pulmonary
artery to avoid sinus node injury (Figure 1A). Phrenic nerve (PN)
capture sites were confirmed following the execution of 5 V pacing
protocols. The SVC was ablated on a point-by-point manner with an
irrigated ablation catheter (FlexabilityTM; Abbott, St
Paul, Minnesota, USA). Radiofrequency (RF) pulses (25 W) were applied
for 30 s, and they were delivered circumferentially with the exceptions
of the PN (Figure1B). If the SVC potential remained after the
circumferential isolation, additional PN capture site applications were
delivered for 20 s at 20 W, while the diaphragmatic movement was
evaluated with fluoroscopy. The endpoint of SVC isolation was
bidirectional block between the SVC and the atrium. Dormant SVC
conduction was induced following the administration of adenosine
triphosphate (20 mg) in the cases at which SVC automaticity was
noticeable during the ablation process.