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
Pulsus paradoxus is a characteristic feature of: 
Select and explain. 
A. Constrictive pericarditis, B. Cardiac Tamponade, C. Hyperophic obstructive cardiomyopathy, D. Restrictive cardiomyopathy
B: Cardiac Tamponade
Answer: B: Cardiac Tamponade 
Explanation: Answer is B (Cardiac Tamponade) Pulsus Paradoxus is most characteristic of cardiac tamponade amongst the options provided. Feature Cardiac Tamponade Constrictive Pericarditis Restrictive Cardiomyopathy RVMI Pulsus paradoxus Common Usually Absent Rare Rare Pulsus Paradoxus is much more common with cardiac tamponade than with constrictive pericarditis of paradoxical pulse is considered more characterstic of cardiac tamponade than constrictive pericarditis. Presence of paradoxical pulse is however not a specific feature of cardiac tamponade