title: Bradydysrhythmias and atrioventricular conduction blocks.
abstract: Bradydysrhythimas include sinus bradycardia, junctional brady-cardia, and idioventricular rhythm, which can be distinguished by examining the tracing for the presence or absence of P waves,noting the morphology of these P waves, and determining the width of the QRS complex. Sinoatrial blocks may occur in either first, second, or third degree varieties. Only second degree sinoatrial block can be detected on the 12-lead ECG. Sinus pause and sinus arrest may mimic second degree sinoatrial block, but their periodicity is irregular. The cyclic variability of sinus arrhythmia is unique; as with the other bradydysrhythmias, it may be innocent or pathologic depending upon clinical circumstances. Atrioventricular blocks may occur, and, similar to sinoatrial blocks, they are also categorized as first-, second-, or third degree. These are of greater clinical relevance than their sinoatrial counterparts.
authors.affiliation: Department of Emergency Medicine, Temple University School of Medicine, 10th Floor, Jones Hall, 3401 North Broad Street, Philadelphia, PA 19140, USA. ufbergjw@tuhs.temple.edu
authors.forename: Jacob W
authors.initials: JW
authors.lastname: Ufberg
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Clark
mesh_terms: D001919:Bradycardia / Q000175:diagnosis* / Q000503:physiopathology; D004562:Electrocardiography; D006801:Humans; D012804:Sick Sinus Syndrome / Q000175:diagnosis* / Q000503:physiopathology; D012848:Sinoatrial Block / Q000175:diagnosis* / Q000503:physiopathology