Catheter ablation of coexistent bundle branch and interfascicular reentrant ventricular tachycardias.

Bundle branch reentry and interfascicular reentry are potential mechanisms of ventricular tachycardia in the setting of a dilated cardiomyopathy. We report a patient with myotonic dystrophy who presented with near syncope, in whom both of these mechanisms were present, leading to two different wide complex tachycardias. Electrophysiologic study demonstrated infra-Hisian conduction system disease and inducible bundle branch reentrant ventricular tachycardia. Catheter ablation of the right bundle eliminated bundle branch reentry. However, following this, the patient had inducible interfascicular reentry, which subsequently occurred spontaneously while still hospitalized. Catheter ablation of the left posterior fascicle successfully eliminated this second tachycardia, and the patient has had no further arrhythmias. This report is of an unusual patient with coexistent bundle branch reentry and interfascicular reentry producing two different forms of sustained ventricular tachycardia. This is the first report of catheter ablation of the left posterior fascicle for elimination of conduction system reentry.