Circuit Localization of Unstable Intramural Ventricular Tachycardia Using Live Directional Activation Mapping; A Potential Mapping Tool for Intramural Arrhythmias

Introduction : Intramural ventricular tachycardia (VT) remains a challenge because of the difficulty in accurately localizing its focus from the surface of the myocardium. Methods and Results : An 83-year-old man with non-ischemic cardiomyopathy experienced unstable sustained monomorphic VT. Suboptimal pacemaps in the epi/endocardium and the absence of diastolic or presystolic local electrograms indicated the intramural focus. Despite the very short recording time, the live activation directional mapping (AD) showed a centrifugal activation pattern at the possible exit site of the epicardium. Based on these findings, bipolar ablation was performed between the epi- and endocardium and successfully eliminated the unstable intramural VT. Conclusions : AD is a time-agnostic live directional mapping application that may provide the information of intramural activation apart from the myocardial surface.