A 6-month-old infant with a known large VSD develops increasing tachypnoea, poor feeding, and growth failure. The harsh pansystolic murmur is now softer. A new soft, mid-diastolic murmur appears at the apex. Chest X-ray shows cardiomegaly with increased pulmonary vascularity. What does the decrease in VSD murmur indicate?
- A Spontaneous closure of the VSD
- B Increasing pulmonary artery pressure equalising with systemic pressure, reducing left-to-right gradient ✓
- C Development of Eisenmenger syndrome with reversal of shunt
- D Infundibular spasm causing temporary reduction in shunting
Explanation
In a large, unrestrictive VSD, as pulmonary hypertension develops over months, the pressure gradient between the left and right ventricles decreases. As pulmonary artery pressure rises towards systemic pressure, the turbulent left-to-right shunt velocity decreases — the harsh pansystolic murmur becomes softer. This is a sign of worsening, not improvement, indicating progressive pulmonary hypertension. The apical mid-diastolic (Carey-Coombs) murmur reflects increased flow across the mitral valve due to large left-to-right shunt. Eisenmenger syndrome is a later irreversible stage when pulmonary resistance exceeds systemic, reversing the shunt to produce cyanosis. Infundibular spasm occurs in Fallot's tetralogy.
Reference: Ghai Essential Pediatrics, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.