title: Reentrant tachycardia associated with atrial synchronous pacing. Report of a case with intact ventriculoatrial conduction.
abstract: Reentrant tachycardia occurred after implantation of an atrial synchronous ventricular-inhibited pacemaker in a patient with bradycardia caused by second-degree (Mobitz II) atrioventricular block. Despite the presence of antegrade atrioventricular block, intact ventriculoatrial conduction was present at a cycle length that exceeded the atrial refractory period of the pacemaker. Consequently, a reentrant or "endless-loop" tachycardia occurred. Application of a magnet terminated the tachycardia. Because the episodes were frequent and could not be prevented by medication, the pacemaker was reprogrammed to a ventricular-inhibited mode. All candidates for atrial synchronous pacing should undergo an appropriate electrophysiologic study preoperatively.
mesh_terms: D001283:Atrioventricular Node / Q000503:physiopathology; D001919:Bradycardia / Q000209:etiology; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects*; D004562:Electrocardiography; D006327:Heart Block / Q000150:complications / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013610:Tachycardia / Q000209:etiology*