Question

Infective Endocarditis is a very rare feature of

• A. Patent ductus arteriosus
• B. Ostium secundum atrial septal defect
• C. Tetralogy of Fallot
• D. Ventricular septal defect

Hint:

Think about which shunt has no real pressure gradient and so no jet lesion.

Answer 1

The Correct Option is B

Step 1: Recall which congenital defects carry endocarditis risk.
Infective endocarditis develops at sites of turbulent blood flow, where a jet of blood hits the endocardium and damages it. This damaged surface lets bacteria stick and grow. Conditions with a high velocity jet, such as PDA, VSD, and Tetralogy of Fallot, carry a real risk of endocarditis.

Step 2: Look at ostium secundum ASD separately.
In an isolated ostium secundum atrial septal defect, blood moves from the left atrium to the right atrium through a large, low pressure opening. The pressure gradient across this defect is small, so there is no forceful jet hitting the endocardium.

Step 3: Connect the mechanism to the outcome.
Because there is no jet lesion, the endocardium near an ostium secundum ASD stays smooth and undamaged. Bacteria have almost nothing to stick to, so infective endocarditis is a very rare complication of this defect, unlike most other congenital shunts.

Step 4: Rule out the other options.
Patent ductus arteriosus (A) has a strong, continuous jet of blood into the pulmonary artery, and this vessel wall site is well known for endarteritis. Tetralogy of Fallot (C) has a large VSD with a high velocity right to left jet, so its endocarditis risk is high. Ventricular septal defect (D) has a strong pressure gradient between the ventricles, producing a jet that damages the opposite wall and predisposes to endocarditis.

Step 5: Final answer.
Infective endocarditis is a very rare feature of an isolated ostium secundum atrial septal defect because there is no significant jet lesion at the defect.
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