Combined intra-Hisian block and A-V nodal bypass.
A patient with first and second degree atrio-ventricular (A-V) block and left bundle branch block was shown on electrophysiological study to have an intra and infra-His bundle branch block. In addition, this patient also had an A-V nodal bypass tract. The intra-Hisian block was concealed on the resting His bundle electrogram and became evident only during atrial pacing. The A-V nodal bypass was masked on the surface electrocardiogram (ECG) by the associated A-V conduction defect. The clinical significance of A-V bypass and combined block below the A-V node is discussed. The diagnostic value of His bundle electrocardiography in a patient with complex electrophysiological abnormalities is stressed.
D000368:Aged; D001283:Atrioventricular Node / Q000503:physiopathology*; D002036:Bundle of His / Q000503:physiopathology*; D002037:Bundle-Branch Block / Q000503:physiopathology*; D004562:Electrocardiography; D006327:Heart Block / Q000503:physiopathology* / Q000628:therapy; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial