title: Significance of first degree heart block (prolonged P--R interval) in bifascicular block.
mesh_terms: D002037:Bundle-Branch Block / Q000503:physiopathology; D004562:Electrocardiography; D006327:Heart Block / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans