title: Wide QRS-complex tachycardia with variable VA-conduction: what is the mechanism?
abstract: We describe the case of a 16-year-old woman with a surgically corrected tetralogy of Fallot presenting with recurrent wide-QRS-complex tachycardia. The tachycardia could be induced and terminated with ventricular stimulation only. QRS morphology during sinus rhythm and tachycardia was identical and variable VA-conduction was observed. Mapping of the tachycardia showed that variations of HH intervals preceded VV intervals. Therefore, a mechanism involving re-entry within the bundle branches was suggested. However, detailed mapping showed cranial to caudal depolarization of the His bundle, leading to the diagnosis of atrioventricular node re-entrant tachycardia. The tachycardia was abolished by radiofrequency catheter ablation of the slow AV nodal pathway. We conclude that variable VA conduction can occur in patients with atrioventricular node re-entrant tachycardia. The atrial tissue is not always an integral part of the re-entrant circuit.
authors.affiliation: Swiss Cardiovascular Center Bern, University Hospital, CH-3010 Bern, Switzerland.
authors.forename: Hildegard
authors.initials: H
authors.lastname: Tanner
authors.forename: Takao
authors.initials: T
authors.lastname: Sakata
authors.forename: Etienne
authors.initials: E
authors.lastname: Delacrétaz
mesh_terms: D000293:Adolescent; D001283:Atrioventricular Node / Q000601:surgery; D002036:Bundle of His / Q000503:physiopathology; D017115:Catheter Ablation; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000503:physiopathology* / Q000601:surgery