A child presenting to the clinic is showing features of Down’s syndrome. Which is the MOST common cardiac lesion in a child with Down’s syndrome?
**Core Concept**
Down's syndrome, a genetic disorder caused by an extra copy of chromosome 21, is associated with various congenital anomalies, including cardiac abnormalities. The most common cardiac lesions in children with Down's syndrome are typically congenital heart defects.
**Why the Correct Answer is Right**
The most common cardiac lesion in children with Down's syndrome is the atrioventricular septal defect (AVSD), also known as atrioventricular canal defect. AVSD is characterized by a defect in the septum between the atria and ventricles, leading to abnormal connections between the atria and ventricles. This can cause blood to flow between the left and right sides of the heart, resulting in oxygenated blood mixing with deoxygenated blood. The pathophysiology of AVSD is related to the abnormal development of the endocardial cushions during embryogenesis, which are crucial for the formation of the atrioventricular septum.
**Why Each Wrong Option is Incorrect**
**Option A:** Ventricular septal defect (VSD) is a common congenital heart defect, but it is not the most common cardiac lesion in children with Down's syndrome.
**Option B:** Tetralogy of Fallot (TOF) is a cyanotic congenital heart defect characterized by four components, including VSD, pulmonary stenosis, right ventricular hypertrophy, and an overriding aorta. While TOF can occur in children with Down's syndrome, it is not the most common cardiac lesion.
**Option C:** Coarctation of the aorta is a narrowing of the aorta, typically occurring in the region of the ductus arteriosus. While it can be associated with Down's syndrome, it is not the most common cardiac lesion.
**Option D:** Patent ductus arteriosus (PDA) is a congenital heart defect characterized by the failure of the ductus arteriosus to close after birth. While PDA can occur in children with Down's syndrome, it is not the most common cardiac lesion.
**Clinical Pearl / High-Yield Fact**
Children with Down's syndrome are at increased risk of developing cardiac anomalies, particularly AVSD. Early detection and management of cardiac lesions are crucial to prevent long-term complications and improve outcomes.
**Correct Answer:** A. Atrioventricular septal defect (AVSD)