Role of ablation therapy in ventricular arrhythmias.

Catheter ablation is an effective therapy for symptomatic ventricular arrhythmia (VA) in patients with and without structural heart disease. It is the treatment of choice to cure or reduce recurrent VA in patients who have an implantable cardioverter defibrillator and can be a life-saving procedure in patients who have electrical storm. Catheter ablation for VAs remains a challenging procedure and requires a precise understanding of cardiac electrophysiology, the arrhythmia mechanisms, and mapping techniques. Various mapping techniques such as pace mapping, activation mapping, entrainment mapping, and substrate mapping are used. These techniques complement each other in localizing the critical isthmus of a reentrant VT or the source of origin of a focal VT. Most VAs can be ablated endocardially. Epicardial ablation is needed for VAs with an epicardial circuit or a focal source.