title: First degree atrioventricular block with periodic variations in conduction time.
abstract: Periodic variations in PR interval from 0.16 sec to 0.36 sec is discussed in a patient without overt cardiac disease. The unequally blockage of slow and fast pathways within the A-V node is proposed as explanation of the phenomenon.
mesh_terms: D000328:Adult; D004562:Electrocardiography; D005260:Female; D006327:Heart Block / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D010507:Periodicity; D013997:Time Factors