Question

What could be the cause of improvement in the condition of a child having a perimembranous VSD and heart failure?

• A. Reduction in size of the VSD
• B. Pulmonary vascular changes
• C. Infective endocarditis
• D. Aortic regurgitation

Hint:

Rising pulmonary vascular resistance from chronic high flow reduces the left to right shunt through the VSD.

Answer 1

The Correct Option is B

This question is about why a child with a large VSD and heart failure may seem to get better over time without any treatment.

1. Reduction in size of the VSD: spontaneous partial closure of a perimembranous VSD does occur in some children and can ease symptoms, but it is not the classic mechanism tested here for a child whose defect stays open.
2. Pulmonary vascular changes: long standing high flow and high pressure in the lung vessels thickens their walls. This raises pulmonary vascular resistance, which opposes and reduces the left to right shunt through the VSD, so the lungs get less extra blood and the failure symptoms lessen.
3. Infective endocarditis: an infection of the heart lining or valves that can complicate a VSD. It makes the child sicker, with fever and new murmurs, it never explains an improvement.
4. Aortic regurgitation: a perimembranous VSD can pull an aortic cusp down into the defect over time, causing valve leakage. This adds more work for the heart and worsens failure, it does not cause improvement.

The correct explanation is that the pulmonary arteries thicken and resist flow, quietly cutting down the shunt and easing the symptoms, a sign that is worrying rather than reassuring because it can progress toward irreversible pulmonary hypertension.

Let's summarize:

• Rising pulmonary vascular resistance reduces the left to right shunt through a VSD.
• This can look like clinical improvement, but it marks the start of pulmonary vascular disease.

So the cause of the apparent improvement is pulmonary vascular changes.