Incessant tachycardia with borderline QRS duration, short HV interval, and left ventricular dysfunction: What is the mechanism?

Successful ablation of incessant idiopathic right ventricular tachycardia arising from unusual sites in children

“…In contrast, tachycardia directly arising from the right bundle branch is very rare. [4][5][6][7] The origins of ventricular tachycardia at the proximal and distal right bundle branch in patients 1 and 2, respectively, were confirmed by the careful mapping of the distribution of entire right bundle branch potential along the septum during an electrophysiology study. In patient 1, the narrow QRS of left bundle branch block morphology, atrioventricular dissociation, and a pre-systolic right bundle branch potential preceding the QRS complex were very suggestive of ventricular tachycardia from the right His-Purkinje system.…”

“…Incremental atrial pacing can overdrive the ventricle with narrow QRS complex until atrioventricular block occurs, which excludes the existence of an atriofascicular accessory pathway of the Mahaim fibre. [6][7][8] Moreover, the evidence for this diagnosis was the transition of a narrow QRS ventricular tachycardia with incomplete left bundle branch block to a wider QRS tachycardia with a right bundle branch block pattern after our first ablation. Complete right bundle branch block was also present in sinus rhythm, which indicates that the ablation site was the right bundle branch distal to the site of ventricular tachycardia.…”

Two apparently remote types of ventricular tachycardia from a single right bundle branch focal source

“…Idiopathic RV arrhythmia originating in the distal RBB or MB is a rare entity of unknown underlying reasons, although increased automaticity is the likely mechanism 7, 8, 9, 10, 11, 12, 13. The clinical manifestation suggesting focal VT does not exclude, for example, arrhythmogenic RV cardiomyopathy 1 .…”

“…In this case, confounding multiple VT morphologies were not related to obvious RV structural disease, and catheter ablation appeared the optimal treatment. Yet, the risk of the development of tachycardia-induced cardiomyopathy8, 11, 12, 13 or MB-related VPC-induced idiopathic ventricular fibrillation 7 emphasizes the need for a case-by-case assessment of sudden cardiac death risk and close monitoring before and after ablation in patients with similar arrhythmia.…”

Idiopathic Accelerated Idioventricular Rhythm or Ventricular Tachycardia Originating From the Right Bundle Branch

“…Similar findings were also presented in previously reported case studies. [18][19][20][21] This activation sequence of the RBB ruled out the possibility of bundle branch reentry or junctional rhythm with LBBB because these rhythms should have an antegrade RBB activation pattern. Also, a sharp, low-amplitude, high-frequency (mahaim-like) potentials were not found to precede the local ventricular activation around the tricuspid annulus.…”