Bundle Branch Reentrant Ventricular Tachycardia With Wide and Narrow QRS Morphology

Abstract

Bundle branch reentrant ventricular tachycardia (BBR-VT) is generally recognized as VT with wide QRS complexes that includes the His-Purkinje system and ventricle in its circuit. BBR-VT is well known to be commonly associated with structural heart diseases and left ventricular dysfunction.1 We report a rare case of BBR-VT displaying wide and narrow type QRS complexes in a patient without obvious structural heart disease or overt ventricular conduction disturbance. Editor’s Perspective see p e92 A 39-year-old man with episodes of wide QRS tachycardia was referred to our institution for electrophysiological study and catheter ablation. ECG during his clinical tachycardia showed left axis deviation and left bundle branch block (LBBB)–type morphology. Baseline 12-lead ECG showed sinus rhythm with no remarkable abnormalities, except for slight right axis deviation (Figure 1A). Transthoracic echocardiography was also normal, with normal values for left ventricular size (diastolic diameter, 46 mm) and systolic function (ejection fraction, 62%). There was nothing suggestive in the patient’s medical history, such as syncope, nor was there any family history of sudden cardiac death. Figure 1. Twelve-lead ECG of sinus rhythm and ventricular tachycardia (VT). A , Sinus rhythm showed slight right axis deviation. B , VT1 showed left bundle branch block pattern. C , VT2 had narrow QRS complexes and similar morphology to that of sinus rhythm. D , VT3 with right bundle branch block morphology was observed after spontaneous conversion from VT2. Diagnostic electrophysiological study demonstrated a normal A-H interval of 78 ms and an H-V interval of 48 ms during sinus rhythm. Programmed ventricular stimulation with single extrastimulus delivered from right ventricular apex revealed decremental ventriculoatrial conduction as S1S2 interval shortened, and V3 phenomenon was observed by an S1S2 interval of 280 ms.2 Sustained LBBB forms wide QRS tachycardia with QRS width of 144 ms and cycle length of 270 …