title: Progressive atrioventricular block after total correction of Fallot's tetralogy, documented by repeat electrophysiological studies.
abstract: A case of progressive trifascicular block late after correction of Fallot's tetralogy is reported. Progressive damage to the His bundle and/or its branches over 18 months after surgery was suggested by sequential ECGs and confirmed by repeat electrophysiological studies done 3 and 18 months postoperatively: the H-V interval increased from 55 to 80 ms over this period. With atrial pacing at increasing rates, supra-His 2:1 atrioventricular (AV) block occurred at a rate of 158/min at the first study; at the second study, infra-His block occurred at an atrial pacing rate of only 128/min. A permanent pacemaker was implanted prophylactically. 5 years after surgery, complete heart block occurred without symptoms, the pacemaker having taken over ventricular stimulation.
mesh_terms: D002036:Bundle of His / Q000503:physiopathology; D002037:Bundle-Branch Block / Q000503:physiopathology; D002648:Child; D004562:Electrocardiography; D006327:Heart Block / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial; D011183:Postoperative Complications / Q000503:physiopathology*; D013771:Tetralogy of Fallot / Q000601:surgery*