title: A study in differential trifascicular refractoriness.
mesh_terms: D002037:Bundle-Branch Block / Q000503:physiopathology*; D005117:Cardiac Complexes, Premature / Q000503:physiopathology; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008875:Middle Aged