RESUMO
Management of patients with ventricular tachycardia (VT) is often difficult. Drug therapy is often ineffective. Implantable cardioverter defibrillators (ICDs) can terminate VT episodes but do not prevent them. Radiofrequency (RF) catheter ablation can suppress arrhythmias in selected patients. However, the procedure is often challenging and success rates lower than for ablation of supraventricular tachycardias. The mapping and ablation approach depends on the VT mechanism. Monomorphic VT in patients without structural heart disease is referred to as idiopathic and has a focal origin. These VTs can be abolished by ablation in most of the patients. In VT due to reentry within an area of scar from an old myocardial infarction or cardiomyopathic process, critical parts of the circuit may be difficult to localize, rendering RF ablation challenging. In patients with monomorphic VT, prevention of VT recurrence can be achieved in 55% to 80% of patients. Multiple morphologies of VTs and circuits that are located deep in the endocardium are common problems that reduce efficacy. Furthermore, mapping to identify target regions for ablation can be more difficult if VT is rapid and not tolerated, or not inducible. Recently, multisite mapping of the arrhythmia substrate during sinus rhythm or multisite activation mapping of a few VT beats were shown to be effective for ablation of these "unmappable VTs". Bundle branch reentry tachycardia occur in patients with nonischemic cardiomyopathies, mostly valvular heart disease and can be successfully abolished with RF ablation of the right bundle. However, some of these patients may develop recurrences due to other types of VT. Recent technical developments have increased efficacy and simplified the approach of RF ablation of VT in patients with structural heart disease. However, long-term efficacy is not accurately predictable and implantation of an ICD is mandatory in most of the patients with severely depressed left ventricular function.
