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.