An irregular pacemaker.
D004562:Electrocardiography; D006327:Heart Block / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial / Q000009:adverse effects*; D010494:Pericarditis, Constrictive / Q000601:surgery; D011183:Postoperative Complications