title: Dual-chamber pacemaker malfunction mimicking atrial capture by the ventricular electrode.
abstract: A 78-year-old man came for a scheduled check up one month after the implantation of a permanent dualchamber pacemaker for symptomatic transient atrioventricular conduction disturbances (intermittent Mobitz II atrioventricular block). The patient's ECG indicated a loss of atrial capture by the atrial electrode with 1:1 atrioventricular conduction. A subsequent X-ray examination showed that both electrodes were well placed and in their correct sites. A detailed check of the pacemaker using the programmer, together with an echocardiographic examination, revealed the true nature of the malfunction: there was a significant delay between the atrial capture and atrial depolarisation and systole, as well as a loss of ventricular capture because of an acute increase in the threshold. Normal pacemaker function and pacing ECG were restored through modification of the pacemaker's functional parameters.
authors.affiliation: 1st Department of Cardiology, St. Panteleimon General Hospital, Nikaia, Piraeus, Greece. pmargos@yahoo.gr
authors.forename: Panagiotis N
authors.initials: PN
authors.lastname: Margos
authors.forename: Alexandros S
authors.initials: AS
authors.lastname: Stefanidis
authors.forename: Evangelos G
authors.initials: EG
authors.lastname: Papasteriadis
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects*; D003937:Diagnosis, Differential; D004868:Equipment Failure; D006327:Heart Block / Q000175:diagnosis* / Q000209:etiology* / Q000628:therapy; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial / Q000009:adverse effects*