title: An unusual narrow QRS complex tachycardia: what is the mechanism?
abstract: The electrocardiogram of a 72-year-old woman showed episodes of nonsustained narrow QRS complex tachycardia. Tracing analysis suggested that the arrhythmia was due to interpolated atrial extrasystoles occurring in bigeminal rhythm. Interpolation of atrial extrasystoles is a rare phenomenon. In this condition, a premature atrial beat is "sandwiched" between 2 normal sinus beats, and sinus PP interval containing the extrasystole is often longer than unaffected sinus cycles. Alternative mechanisms for the arrhythmia are discussed, such as: (1) sinus node reentry; (2) 1:2 response to atrial ectopy over the fast and the slow atrioventricular nodal pathways; and (3) couplets of atrial extrasystoles.
authors.affiliation: Department of Medicine and Pharmacology, University of Messina, Messina, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Carbone
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Marafioti
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Oreto
mesh_terms: D000368:Aged; D004562:Electrocardiography; D005260:Female; D006801:Humans; D013617:Tachycardia, Supraventricular / Q000175:diagnosis* / Q000503:physiopathology*
keywords: atrial extrasystoles; bigeminal rhythm; interpolation; narrow QRS complex tachycardia