Electroanatomic localization of idiopathic ventricular arrhythmia origins in the left ventricular outflow tract

Idiopathic ventricular arrhythmias (VAs) originate from endocardial and epicardial or intramural sites in the left ventricular outflow tract (LVOT). Several specialized ablation techniques such as sequential or simultaneous unipolar ablation, bipolar ablation, and anatomic ablation have been developed to treat those epicardial and intramural VAs. Because those ablation techniques eliminate VA origins across the muscle wall remotely from a different anatomic location, the anatomic sites of successful ablation do not necessarily indicate the true anatomic locations of VA origins. However, localization of VA origins is important when the detailed electrocardiographic and electrophysiological characteristics and ablation outcome of LVOT VAs are examined. This review discusses the anatomic background relevant to catheter ablation and the distinctive electrophysiological findings that specifically determine the anatomic locations of idiopathic LVOT VA origins and presents a novel concept, that is, electroanatomic localization of those VA origins that is derived by considering both the anatomy and electrophysiology.