Outflow Tract PVCs: What We Know and We Don’t Know

The ventricular outflow tract has been known as the most common site of premature ventricular contraction (PVC) origins (the right ventricular outflow tract [RVOT] is more common than the left ventricular outflow tract [LVOT]). The electrocardiographic and electrophysiological characteristics as well as anatomical background of those PVCs have been progressively elucidated, and the outcome of the catheter ablation of those PVCs has been improved. Anatomically, the RVOT and LVOT are located next to each other, and a preferential conduction across the ventricular outflow tract may occur. Therefore, the electrocardiograms of the PVCs originating from the RVOT or LVOT are similar, and are sometimes difficult to differentiate. The structure of the ventricular outflow tract is complex with valves and epicardial heart vessels as adjacent structures. The ventricular muscle extends above the pulmonary valve whereas it does not above the aortic valve. PVCs originating from the ventricular outflow tract can be ablated above and below the valves endocardially and sometimes epicardially through a transvenous and transpericardial approach. Catheter ablation of these PVCs is usually very successful and safe, but that of PVCs originating from intramural and epicardial foci remains challenging. PVCs originating from the RVOT may trigger ventricular fibrillation or polymorphic ventricular tachycardias in patients with Brugada syndrome, long QT syndrome, and idiopathic ventricular fibrillation. Therefore, catheter ablation of RVOT PVCs can treat ventricular fibrillation.

The purpose of this symposium will be to review and discuss the previous important findings about outflow tract PVCs and reveal the remaining questions about those VAs for future studies.