Fascicular and Papillary Muscle Arrhythmias in the Structurally Normal Heart.

Arrhythmias originating from the specialised cardiac conduction system and papillary muscles can occur in both structurally normal and diseased hearts. Conduction system associated arrhythmias include bundle branch re-entry, fascicular re-entry, non-re-entrant fascicular ventricular tachycardia and idiopathic ventricular fibrillation. Each type of arrhythmia requires a unique diagnostic and therapeutic approach. The papillary muscles may also be a source of ventricular arrhythmias. Ablation of papillary muscle associated arrhythmias may be difficult due to the complexities of mapping, structural abnormalities and potentially the deep location of arrhythmia foci. Tools, such as intracardiac echocardiography, can be valuable.