title: An unusual case of second-degree A-V block--a study using His bundle electrograms.
mesh_terms: D004562:Electrocardiography; D005260:Female; D006327:Heart Block / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D008875:Middle Aged; D010138:Pacemaker, Artificial