Bundle Branch Reentrant Ventricular Tachycardia

Abstract

Macroreentrant circuit involving the bundle branches or the fascicles can develop bundle branch reentrant ventricular tachycardia (BBR-VT) in patients with conduction disturbance within the His-Purkinje system, which is associated with organic heart diseases and severe LV dysfunction. BBR-VT usually exhibits the QRS morphology with a left bundle branch block (LBBB) configuration or rarely a right bundle branch block (RBBB) pattern. In LBBB type BBR-VT, the right bundle branch (RB) constitutes the antegrade limb of reentrant circuit, and the retrograde limb is the left bundle branch (LB).

Diagnostic features suggestive of BBR-VTD are as follows: (1) Induction of BBR-VT during ventricular stimulation depends on His-Purkinje conduction delay. (2) The onset of the ventricular depolarization is preceded by the His potentials. (3) The H-V, RB-V, or LB-V interval during the tachycardia is longer than or equal to each interval during sinus rhythm. (4) Variations in the H-H, RB-RB, or LB-LB interval during the tachycardia precede the changes in the V-V interval. (5) The QRS morphology during atrial entrainment is identical to the QRS morphology during BBR-VT. (6) The difference between the postpacing interval after entrainment from the right ventricular apex and the tachycardia cycle length is less than 30 ms.

Catheter ablation of the RB is recommended and an effective therapy for treatment for BBR-VT. However, the prognosis is often poor in patients followed after successful ablation of BBR-VT because they have underlying structural heart disease and severe LV dysfunction. Therefore, ICD or CRT-D should be considered for the prevention of sudden cardiac death in these patients.