Ventricular Arrhythmias Originating from Parahisian Area

Ventricular arrhythmias (VAs) originating from parahisian (PH) area has not been fully understood. This study was to investigate the electrocardiographic and electrophysiologic characteristics and results of Catheter ablation (CA) of VAs originating from PH area. Methods: Among 302 consecutive patients who underwent CA for ventricular tachycardia (VT) or symptomatic premature ventricular complexes (PVCs), 6 patients (2.0%, 43 ±8 years) were found to have successful CA site at PH area. Results: All but one patient had normal LV systolic function. Mean QRS width of VT/PVC was 114.3±19.9ms, which was narrower than other sites (147.0 ±15.3ms, P=0.008), inferior axis in 5 patients, positive in aVL in 4 patients, and right (RBBB) in 2 and left bundle branch block (LBBB) in 4. VT was inducible by programmed ventricular stimulation in 2 and PVCs provocated during isoproterenol infusion in 3. Activation mapping in the LV (n=3) or RV (n=3) revealed earliest activation times was 32.0±10.7ms before QRS. In 5 patients, His potential was recorded at the site of successful ablation. The CA was unsuccessful in 1 and 2 patients had recurrent VAs. Redo CA was successful in 1. One underwent pacemaker implantation due to complete atrioventricular block after CA. Conclusions: VAs originated from PH area were characterized by narrower QRS width, either LBBB or RBBB with inferior axis, positive QRS in aVL, and caused by either triggered activity or reentry.