Spatial Distribution of Idiopathic Ventricular Arrhythmias Originating Around the Pulmonary Root

The purpose of this study was to investigate the spatial distribution of ventricular arrhythmias (VAs) and their relationship with anatomic landmarks in the right ventricular outflow tract (RVOT).Although controversy has mainly focused on whether VAs ablated in the RVOT originate above or below the pulmonary sinus, little is known about their actual distribution.We performed mapping and ablation in the reconstructed RVOT using intracardiac echocardiography (ICE) and summarized the spatial electroanatomic characteristics of RVOT-VAs.A total of 50 VAs were recruited and were distributed among the 3 subregions: the pulmonary sinuses (19 of 50, 38%), sinus junctions (18 of 50, 36%), and infundibulum (13 of 50, 26%). In total, 70% (35 of 50) of ablation targets were within 10 mm (mean 4.3 ± 2.7 mm) of the pulmonary valve hinge point. An ablation target with both amplitude ≤1.14 mV and duration ≥101.5 milliseconds predicted an origin above the pulmonary sinus with a sensitivity of 84.2% and specificity of 84.4%. For the ablation targets (13 of 50, 26%) located in the infundibulum of the RVOT, 4 were surrounded by trabeculations, whereas only 1 ablation target in the sinus junction abutted the trabeculation (30.8% vs 5.6%).Ablation targets of RVOT-VAs were mainly distributed around the hinge point of the pulmonary valve and the trabeculation of the infundibulum. ICE can clearly and precisely locate those anatomic landmarks of the RVOT.