Ablation of Unstable Ventricular Tachycardia

Abstract

It is critical to begin any discussion on ablation of unstable ventricular tachycardia with background information supporting the importance of the effort. First, stable, mappable ventricular tachycardias represent the tip of the arrhythmia iceberg. In order for any arrhythmia to be mappable it must be reliably inducible and hemodynamically tolerable. The ventricular tachycardia must also be stable in response to the catheter manipulation and pacing required to identify the appropriate site for ablative therapy during activation and entrainment mapping [1–4]. In a consecutive series of “ideal” patients presenting with hemodynamically tolerated ventricular tachycardia and referred for catheter ablation, 30% had only unmappable VT at the time of electrophysiological evaluation [5]. Secondly, ICD event monitoring after device implantation has documented rapid unmappable VT in most patients regardless of the clinical indication for initial device therapy [6–8]. Finally, in looking to the future, a strategy for prevention of sudden cardiac death that uses ablative therapy must target the substrate for unmappable ventricular tachycardia [9].