Mapping and ablation
Electrophysiological study and ablation were performed after
discontinuation of all antiarrhythmic drugs for at least five
half-lives. A 6F decapolar catheter (4-mm interelectrode spacing) was
inserted from the right internal jugular vein and placed in the coronary
sinus. If clinical arrhythmias failed to occur spontaneously,
intravenous isoproterenol infusion (2–5 mg/min) was administered. An
irrigated-tip ablation catheter was advanced to the right ventricle and
coronary venous system via antegrade transvenous approach and to the
left ventricle via retrograde aortic approach. The RVOT, LV endocardium,
aortic cusp, and DGCV-AIV were mapped with the ablation catheter to
identify the earliest site of ventricular activation during VAs.
Activation mapping was preferentially used to identify the origin during
the procedure. Pace-mapping was also performed to capture the
ventricular myocardium at the site of earliest activation. A suitable
target for ablation was selected based on the earliest activation times
during the arrhythmia combined with pace mapping. Once the origin of VAs
was found within ASCs or PSCs, RFCA would be attempted by the
irrigated-tip catheter in a power-controlled mode with a maximum
temperature of 43 °C, preset power of 35 W, and flow rate of 17 ml/min.
For DGCV-AIV, the irrigated-tip was applied with a flow rate of 30-60
ml/min, preset power of 25-30 W. CAG was performed in all cases to
investigate distance from the catheter tip to adjacent coronary arteries
before RFCA. Energy delivery was forbidden when the distance was less
than 5mm. Coronary blood supply was routinely evaluated before and after
ablation. If VAs were terminated or accelerated during the initial 10 s,
radiofrequency delivery would be continued for 60 to 180 s. Otherwise,
other targets were sought.
After successful ablation, intravenous administration of isoproterenol
and programmed stimulation were performed to induce clinical VA. Acute
success was defined as both absence of spontaneous or provoked clinical
VA at the end of the procedure and the latter 48-hours period
post-ablation on ECG Holter.
Swartz sheath support
approach and non-Swartz sheath support approach
When the DGCV-AIV was considered the origin of ventricular arrhythmias,
detailed mapping in DGCV-AIV was performed. For mapping and ablation in
DGCV-AIV, two catheter manipulation approaches could be adopted, and
shown in Figure1 . The
conventional approach, non-Swartz sheath support (NS) approach, was
facilitated by delivering the tip of ablation catheter directly from the
ostium of coronary sinus to DGCV-AIV to perform mapping and ablation.
The Swartz sheath support (SS) approach was facilitated by engagement of
Swartz sheath in GCV from the ostium of coronary sinus by ablation
catheter. Then the ablation catheter and Swartz sheath were advanced
alternately in GCV to reach the distal portion of DGCV-AIV to perform
mapping and ablation. If the Swartz sheath still could not go through
the GCV, the hydrophilic coated guide wire and Judkins’ 4-left coronary
catheter-guided deep engagement of Swartz sheath in GCV was conducted to
support ablation catheter.