title: 2:1 atrial capture as the cause of pacemaker alternans.
abstract: Two patients with sinus node disease and a physiologic pacemaker presented with 2:1 atrial capture. Both atrial leads were screw-in leads (6957 J, Medtronic), with normal position on X-rays. When atrial capture was absent, paced QRS complexes resulted in retrograde conduction to the atria. The next atrial spike was followed by a P wave and normal AV conduction. With atrial screw-in leads, alternating atrial capture may be caused by an altered ventricular and atrial contraction pattern, when retrograde conduction exists. Its presence may precede permanent exit block by several weeks.
authors.affiliation: Department of Cardiology, University Hospital State University, Ghent, Belgium.
authors.forename: L J
authors.initials: LJ
authors.lastname: Jordaens
authors.forename: E
authors.initials: E
authors.lastname: van Wassenhove
authors.forename: D L
authors.initials: DL
authors.lastname: Clement
mesh_terms: D000368:Aged; D004562:Electrocardiography; D004868:Equipment Failure; D005260:Female; D006325:Heart Atria / Q000503:physiopathology; D006327:Heart Block / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial / Q000009:adverse effects*