title: Pacemaker-mediated tachycardias: a new modality of treatment.
abstract: Three patients with pacemaker interactive drug resistant tachycardia underwent invasive electrophysiological studies. In the first patient, the retrograde conduction of the artificial reciprocating tachycardia was provided by two right-sided accessory pathways and the antegrade conduction by an atrial synchronous pulse generator. In addition, AV-nodal tachycardia occurred alternately. In the second patient with intermittent atrial flutter, the AV node and, coincidentally, an AV sequential pulse generator provided high-rate antegrade conduction to the ventricles. In the third patient with surgical complete heart block, intermittent AV-nodal tachycardia induced retrograde atrial activation while an atrial synchronous pacemaker provided the antegrade conduction. Electrode catheter exploration of the heart allowed localization and closed-chest ablation of the accessory pathways or AV node by delivering two to seven 200-joule direct-current shocks through the appropriate electrode of the exploring catheter. Thereby, pacemaker-mediated arrhythmias could be controlled in these patients in the follow-up of 6 to 8 months.
mesh_terms: D000328:Adult; D001283:Atrioventricular Node / Q000503:physiopathology; D006328:Cardiac Catheterization / Q000379:methods; D002648:Child; D004562:Electrocardiography; D004567:Electrodes, Implanted; D004594:Electrophysiology; D006327:Heart Block / Q000503:physiopathology; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial / Q000009:adverse effects*; D013610:Tachycardia / Q000209:etiology* / Q000503:physiopathology / Q000628:therapy