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': 'A 34-year-old man presents with dyspnea and increasing peripheral edema. He recently had a "flu-like" illness with intermittent sharp left-sided chest pain. On examination, his jugular venous pressure (JVP) is elevated at 8 cm, heart sounds are soft, and the blood pressure (BP) is 104/76 mm Hg with a 20 mm Hg decrease in systolic arterial pressure during slow inspiration. Which of the following is the most likely diagnosis? \nSelect and explain. \nA. cardiac tamponade, B. pulmonary hypertension, C. ventricular septal defect, D. coarctation of the aorta', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The drop in systolic pressure with inspiration is an important clue to cardiac tamponade, called pulsus paradoxus. When severe, the arterial pulse may weaken on palpation during inspiration. Pulsus paradoxus is uncommon in constrictive pericarditis and rare in restrictive cardiomyopathy. It is commonly found in severe asthma as well.', 'role': 'assistant'}]