title: QRS alternans with 2:1 atrioventricular conduction block: what is the mechanism?
abstract: An 81-year-old woman was admitted for symptomatic bradycardia. On admission, the ECG exhibited QRS alternans, narrow QRS complex and left bundle branch block with 2:1 AV block. The patient soon had complete AV block and underwent a pacemaker implantation. An appropriate mechanism for explaining those ECG findings might be 4:1 conduction over the left bundle branch and 2:1 conduction over the right bundle branch. An ECG pattern exhibiting QRS alternans with a narrow QRS complex and bundle branch block with 2:1 AV block may suggest the coexistence of both bundle branch blocks and a high risk of complete AV block.
authors: Division of Cardiovascular Disease, University of Alabama at Birmingham, Birmingham, AL 35294-0019, USA. takumi-y@fb4.sonet.ne.jp
authors: Takumi
authors: T
authors: Yamada
authors: Paul B
authors: PB
authors: Tabereaux
authors: H Thomas
authors: HT
authors: McElderry
authors: G Neal
authors: GN
authors: Kay
mesh_terms: D000368:Aged; D054537:Atrioventricular Block / Q000175:diagnosis* / Q000628:therapy*; D001919:Bradycardia / Q000175:diagnosis / Q000209:etiology; D002037:Bundle-Branch Block / Q000175:diagnosis*; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D010138:Pacemaker, Artificial; D018570:Risk Assessment; D012720:Severity of Illness Index; D016896:Treatment Outcome