title: Horizontal and longitudinal dissociation of the A-V node during atrial tachycardia.
abstract: The co-existence of horizontal and longitudinal dissociation of the atrioventricular (A-V) node has not previously been reported. Analysis of ECG tracings from 4 patients with supraventricular tachycardias showing an irregular ventricular rate suggest that such a mechanism was responsible for the irregular A-V conduction pattern. His bundle recording was obtained in one patient and revealed the site of block to be located in the A-V node. Multi-level block and longitudinal dissociation of the A-V node is probably not rare and should be included in the discussion of supraventricular arrhythmias displaying irregular ventricular rates.
mesh_terms: D000328:Adult; D001283:Atrioventricular Node / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D006325:Heart Atria / Q000503:physiopathology; D006327:Heart Block / Q000503:physiopathology; D006329:Heart Conduction System / Q000503:physiopathology*; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D013610:Tachycardia / Q000503:physiopathology*