The electrocardiograph and its interpretation.
D001145:Arrhythmias, Cardiac / Q000175:diagnosis; D006332:Cardiomegaly / Q000175:diagnosis; D003327:Coronary Disease / Q000175:diagnosis; D004562:Electrocardiography; D006801:Humans; D006947:Hyperkalemia / Q000175:diagnosis; D007008:Hypokalemia / Q000175:diagnosis; D010493:Pericarditis / Q000175:diagnosis