Reverse-Type Left Posterior Fascicular Ventricular Tachycardia: A New Electrocardiographic Entity

Catheter Ablation for Ventricular Tachycardia Involving the His-Purkinje System: Fascicular and Bundle Branch Reentrant Ventricular Tachycardia

The Purkinje system has been found to mediate several monomorphic ventricular tachycardias (VTs). These include fascicular VTs and bundle branch reentrant (BBR) VTs. Previous studies have revealed that VTs involving the His-Purkinje system are composed of multiple discrete subtypes that are best differentiated by their mechanism, drug effect, VT morphology, and successful ablation site. Recognition of the heterogeneity of these VTs and their unique characteristics should facilitate the appropriate diagnosis and therapy and help guide catheter ablation therapy. In this article, we focus on the latest updates of the mechanisms underlying left ventricle fascicular VTs and BBR-VTs as well as the latest catheter ablation techniques.

Diagnosis and Management of Complex Reentrant Arrhythmias Involving the His-Purkinje System

The His-Purkinje system is a network of bundles and fibres comprised of specialised cells that allow for coordinated, synchronous activation of the ventricles. Although the histology and physiology of the His-Purkinje system have been studied for more than a century, its role in ventricular arrhythmias has recently been discovered with the ongoing elucidation of the mechanisms leading to both benign and life-threatening arrhythmias. Studies of Purkinje-cell electrophysiology show multiple mechanisms responsible for ventricular arrhythmias, including enhanced automaticity, triggered activity and reentry. The variation in functional properties of Purkinje cells in different areas of the His-Purkinje system underlie the propensity for reentry within Purkinje fibres in structurally normal and abnormal hearts. Catheter ablation is an effective therapy in nearly all forms of reentrant arrhythmias involving Purkinje tissue. However, identifying those at risk of developing fascicular arrhythmias is not yet possible. Future research is needed to understand the precise molecular and functional changes resulting in these arrhythmias.