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': 'Continuous murmur is present in \nSelect and explain. \nA. cardiomyopathy, B. MS, C. PDA, D. cardiac tamponade', 'role': 'user'}, {'content': 'Answer: C \nExplanation: A continuous murmur is predicated on\xa0a pressure gradient that persists between\xa0two cardiac chambers or blood vessels\xa0across systole and diastole.The murmurs\ntypically begin in systole, envelop the\xa0second heart sound (S 2 ), and continue\xa0through some portion of diastole.\nThey\xa0can often be difficult to distinguish from\xa0individual systolic and diastolic murmurs\xa0in patients with mixed valvular heart disease.\xa0\nThe classic example of a continuous\xa0murmur is that associated with a patent\xa0ductus arteriosus, which usually is heard\xa0in the second or third interspace at a slight\xa0distance from the sternal border. Other\xa0causes of a continuous murmur include\xa0a ruptured sinus of Valsalva aneurysm\xa0with creation of an aortic–right atrial\xa0or right ventricular fistula, a coronary\xa0or great vessel arteriovenous fistula, and\xa0an arteriovenous fistula constructed to\xa0provide dialysis access.', 'role': 'assistant'}]