The protocol of SVC isolation
Firstly, electroanatomical SVC
maps were created using a Pentaray catheter during sinus rhythm. The
local SVC potentials were recorded from the ablation catheter. To
determine the site of the phrenic nerve, high output pacing (10V) was
performed. The sites where phrenic nerve stimulation was observed, were
marked as a phrenic nerve position on the SVC map. The AI was blinded to
the operator, and the circumferential SVC isolation was performed 1 cm
above the earliest activation sites during sinus rhythm. The RF energy
was set at 20W-25W and was decreased to 15W-20W in the phrenic nerve
area or area close to the sinus node. Ablation was discontinued
immediately when a decrease in the diaphragmatic movement was observed
on the fluoroscopic image. The endpoint of the SVCI was the
disappearance of all SVC potentials, and bidirectional block was
confirmed by pacing from the ablation catheter in the SVC. We also
confirmed dormant conduction after an intravenous injection of
isoproterenol and adenosine triphosphate.