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?
**Core Concept**
The question is testing the understanding of aortic regurgitation, a condition where the aortic valve fails to close properly, allowing blood to flow back from the aorta into the left ventricle. This can lead to volume overload and eventual left ventricular dilation.
**Why the Correct Answer is Right**
The most likely cause of aortic regurgitation in a 5-year-old boy is a congenital defect, specifically a bicuspid aortic valve. This condition occurs when the aortic valve develops with only two cusps instead of the normal three, leading to incomplete closure and regurgitation. The bicuspid aortic valve is a common congenital heart defect, often associated with other cardiovascular abnormalities.
**Why Each Wrong Option is Incorrect**
**Option A:** **Infective Endocarditis** - While infective endocarditis can cause aortic regurgitation, it is more common in adults and would typically present with fever, heart failure symptoms, and embolic phenomena.
**Option B:** **Rheumatic Heart Disease** - Although rheumatic heart disease can cause aortic regurgitation, it is rare in children under 5 years old and would typically present with a history of rheumatic fever.
**Option C:** **Aortic Dissection** - Aortic dissection is a medical emergency that can cause aortic regurgitation, but it is extremely rare in children and would typically present with severe chest pain and hemodynamic instability.
**Clinical Pearl / High-Yield Fact**
The bicuspid aortic valve is a common congenital heart defect that can be asymptomatic for many years, making regular echocardiographic monitoring essential in children with this condition.
**Correct Answer:** C. A congenital bicuspid aortic valve is the most likely cause of aortic regurgitation in a 5-year-old boy.