This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Medicine
[{'content': 'Pulsus paradoxus is characteristic feature of \nSelect and explain. \nA. Constrictive pericarditis, B. Cardiac tamponade, C. Hyperophic obstructive cardiomyopathy, D. Restrictive cardiomyopathy', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref Harrison 19 th ed pg 1574 Paradoxical Pulse This impoant clue to the presence of cardiac tamponade consists of a greater than normal (10 mmHg) inspiratory decline in systolic aerial pressure. When severe, it may be detected by palpating weakness or disappearance of the aerial pulse during inspiration, but usually sphygmomanometric measurement of systolic pressure during slow respiration is required.', 'role': 'assistant'}]