This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Valvular hea diseases, Subject name: Medicine
[{'content': 'A 5-year-old boy is referred to a pediatric cardiologist after a check-up at his GP revealed he had a murmur consistent with aoic regurgitation. What is the MOST likely cause of this defect? \nSelect and explain. \nA. Atrial septal defect, B. Rheumatic fever, C. Cardiomyopathy, D. Ventricular septal defect', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Option A: ASD= Shunt murmur absent, flow murmur is mid diastolic murmur. Option B: In Rheumatic- mc valve involved is Mitral & 2nd mc Aoic valve, but in 5 yr. old child only Aoic regurgitation is seen (rare) Option C: HOCM causes= Systolic murmur DCM=Functional MR & TR= Systolic Murmur Option D: Ventricular septal defect 3 varieties Muscular Membranous Supra-Cristal variety with associated with AR In 5 year child rheumtic hea disease involving isolated aoic valve is unlikely .most common valve involved in RHD is mitral valve.', 'role': 'assistant'}]