This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'Electric altemans is seen in: \nSelect and explain. \nA. Cardiac tamponade, B. Restrictive cardiomyopathy, C. Constructive pericarditis, D. Right Ventricular MI (RVMI)', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer is A (Cardiac tamponade) Electrical alternans refers to a beat-to-beat alteration in one or more components of the ECG signal. Total electrical alternans (P-QRS-T) with sinus tachycardia is a relatively specific sign for pericardial effusion, often with cardiac tamponade. Feature Cardiac Tamponade Constrictive Pericarditis Restrictive Cardiomyopathy RVMI Electrical Alternans May be present Absent Absent Absent', 'role': 'assistant'}]