title: The William Nelson ECG quiz.
mesh_terms: D000368:Aged; D018880:Atrial Premature Complexes / Q000175:diagnosis; D002037:Bundle-Branch Block / Q000175:diagnosis*; D004562:Electrocardiography; D006801:Humans; D008297:Male; D018879:Ventricular Premature Complexes / Q000175:diagnosis