An Uncommon Type of Bundle Branch Reentrant Tachycardia in Hypertrophic Cardiomyopathy

Bundle branch reentrant tachycardia (BBRT) is an uncommon ventricular tachycardia (VT) and is presented with a long His-ventricular (H-V) interval as a reentry between the bundle branches. This arrhythmia is frequently seen in patients with a significant conduction system disorder. QRS morphology during VT is usually the left bundle branch block (LBBB) type and may be similar to that in sinus rhythm. While BBRT usually has LBBB-like morphology, in rare cases it can be seen with the right bundle branch block (RBBB) form. Most patients have prolonged H-V intervals during sinus rhythm, consistent with His–Purkinje disease; however, some patients may have normal H-V intervals. The ablation of RBBB can cure it, but up to 30% of patients may need pacemaker implantation after ablation. BBRT is responsible for about 6% of induced VTs during the electrophysiology study. We herein present an uncommon form of BBRT (the RBBB type) in a patient who had hypertrophic cardiomyopathy with a normal left ventricular function. (Iranian Heart Journal 2022; 23(4): 131-134)