Methods
From patients referred for VT ablation, 6 patients were identified who
had VT inducible from outside of the right ventricular apical or outflow
region. Patients underwent electrophysiological studies and ablation
according to the previously published method.7–10 An
informed consent was obtained prior to the ablation procedure. Either
Monitored Anesthesia Care (MAC) or general anesthesia was delivered by a
dedicated anesthesia team throughout the procedure. Electroanatomic maps
were constructed using a 3D mapping system (CARTO3, Biosense Webster)
and intracardiac echocardiography (ICE). Programmed electric stimulation
protocol involved 1-3 extrastimuli after two paced cycle length
(typically 400 and 600ms) from two sites (typically the RV apex or
septum and the RVOT). Additional stimulation sites and use of 4
extrastimuli were chosen at the discretion of the operator. Data
collection was performed under protocols approved by the institutional
review board. This research adheres to the ethical guidelines specified
in Helsinki Declaration as revised in 2013.