Electrophysiologic study, mapping, and ablation
Electrophysiologic study, mapping, and ablation were performed in
patients with the periaortic VTs. Electroanatomic mapping (Carto3,
Biosense Webster, USA, California, Irvine) was performed during sinus or
paced rhythm to define the areas of low voltage and scarring (bipolar
and unipolar voltage cutoffs: <1.5 and <8.3 mV,
respectively). The left ventricle (LV) was accessed mainly with the
trans-septal or retrograde aortic approach in patients with a biological
aortic valve. In those with a mechanical aortic valve, the valve was not
crossed in a retrograde fashion. When
sustained
VTs were not present spontaneously,
programmed
electrical stimulation, burst pacing, and
isoproterenol
infusion (1–10 μg/min) were used to provoke
ventricular
arrhythmias. Ablation was performed using a non-irrigated 4.0-mm tip
catheter (CARTO Navistar Catheter, Biosense Webster) with a power of
30–40 W and a temperature limit of 50 °C. The ablation was deemed
successful if there was immediate suppression and sustained VTs were
absent after repeating the induction protocol.