title: Narrow QRS tachycardia with ventriculoatrial dissociation mediated by a left fasciculoventricular fiber.
abstract: A 30-year-old man presented with narrow QRS tachycardia. The intracardiac electrocardiogram showed an atrial-HIS (AH) interval of 75 msec and a HIS-ventricular (HV) interval of 44 msec during baseline. Atrial incremental pacing revealed HV shortening, with apparent incomplete right bundle branch block (RBBB) morphology without QRS complex axis deviation. The induced tachycardia exhibited several QRS morphologies: a narrow QRS, complete RBBB and complete left bundle branch block (LBBB) morphology. Spontaneous conversion of the QRS pattern from wide to narrow was observed. The cycle length of the tachycardia was significantly shortened (from 316 to 272 ms) from LBBB morphology to narrow QRS complex. The atrial activation was dissociated from the ventricular activation during all tachycardias. Each QRS complex during tachycardia was preceded by a HIS deflection and HV interval was 35 ms, which was shorter than that of sinus rhythm. HIS deflection was earlier than right bundle potential during all kinds of tachycardia. This tachycardia is most likely mediated by a left fasciculoventricular fiber which connects the HIS bundle below the atrioventricular node to the myocardial tissue of the left ventricle. The HIS-Purkinje system is used as an antegrade conduction limb and the fasciculoventricular fiber as a retrograde limb in the tachycardia circuit.
authors.affiliation: Department of Cardiology, First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China.
authors.forename: Kejiang
authors.initials: K
authors.lastname: Cao
authors.forename: Minglong
authors.initials: M
authors.lastname: Chen
authors.forename: Jiangang
authors.initials: J
authors.lastname: Zou
authors.forename: Qijun
authors.initials: Q
authors.lastname: Shan
authors.forename: Chun
authors.initials: C
authors.lastname: Chen
authors.forename: Bing
authors.initials: B
authors.lastname: Yang
authors.forename: Li
authors.initials: L
authors.lastname: Zhu
authors.forename: Dongjie
authors.initials: D
authors.lastname: Xu
authors.forename: Yan
authors.initials: Y
authors.lastname: Jin
authors.forename: Bernd-Dieter
authors.initials: BD
authors.lastname: Gonska
mesh_terms: D000328:Adult; D001283:Atrioventricular Node / Q000503:physiopathology*; D002037:Bundle-Branch Block / Q000175:diagnosis / Q000209:etiology; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D013610:Tachycardia / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology