title: A His bundle extrasystole can both induce and reverse 2:1 atrioventricular block.
abstract: An 84 year-old man with history of recurrent dizziness presented with first degree atrio-ventricular block (1° AVB) and periods of 2:1 AVB. An electrophysiological study revealed a predominant 1:1 AV conduction with markedly prolonged AH interval and frequent His bundle extrasystoles (H). A properly timed H could induce periods of 2:1 AV nodal block and 1:1 AV conduction could only resume following another properly timed H. Procainamide suppressed H. However, because of persistence of the patient symptoms, a permanent pacemaker was eventually inserted. The case illustrates a hitherto not described manifestation of H.
authors.affiliation: Downstate Medical Center and New York Harbor VA Healthcare Center, State University of New York, Brooklyn, NY, USA.
authors.forename: Abdullah
authors.initials: A
authors.lastname: Khan
authors.forename: Abdul
authors.initials: A
authors.lastname: Ameen
authors.forename: Ilir
authors.initials: I
authors.lastname: Maraj
authors.forename: Gioia
authors.initials: G
authors.lastname: Turitto
authors.forename: Nabil E
authors.initials: NE
authors.lastname: El-Sherif
mesh_terms: D000369:Aged, 80 and over; D054537:Atrioventricular Block / Q000150:complications / Q000175:diagnosis* / Q000628:therapy; D002036:Bundle of His / Q000503:physiopathology; D002037:Bundle-Branch Block / Q000150:complications / Q000175:diagnosis* / Q000628:therapy; D005117:Cardiac Complexes, Premature / Q000150:complications / Q000175:diagnosis* / Q000628:therapy; D004562:Electrocardiography; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial; D012720:Severity of Illness Index; D016896:Treatment Outcome