title: Narrow irregular QRS tachycardia with AV dissociation: what is the mechanism?
abstract: A 39-year-old woman with no structural heart disease and frequent episodes of sudden onset palpitations was referred for the electrophysiological study. During the study, a slightly irregular narrow QRS tachycardia with AV dissociation was repeatedly induced and spontaneously terminated. Apparently, irregular cycles and termination of the tachycardia were related to the dissociated sinus rhythm: atrial depolarizations timed when the AV junction was refractory were able to reset the tachycardia, while early atrial depolarizations caused its termination. This observation was enough to diagnose the tachycardia mechanism in our case.
authors.affiliation: Electrophysiology Unit, Department of Cardiology, Virgen de la Arrixaca University Hospital, Murcia, Spain. jesus_kastillo@hotmail.com
authors.forename: Jesús
authors.initials: J
authors.lastname: Castillo Castillo
authors.forename: Pablo
authors.initials: P
authors.lastname: Peñafiel Verdú
authors.forename: Juan
authors.initials: J
authors.lastname: Martínez Sánchez
authors.forename: Arcadi
authors.initials: A
authors.lastname: García Alberola
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D011237:Predictive Value of Tests; D012032:Refractory Period, Electrophysiological; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000175:diagnosis* / Q000503:physiopathology; D013613:Tachycardia, Ectopic Junctional / Q000175:diagnosis* / Q000503:physiopathology; D013997:Time Factors