Blood Flow Dynamics in VSD

Steps:

• Left ventricle generates higher pressure than right ventricle due to systemic resistance.
• Hole in septum allows blood to shunt from left (high pressure) to right (low pressure) ventricle.
• This left-to-right shunt recirculates oxygenated blood to lungs, increasing pulmonary volume.
• Systemic circulation receives normally oxygenated blood, maintaining tissue delivery.

Why D is correct:

• Left-to-right shunting in VSD elevates pulmonary blood flow (statement 2) while preserving normal systemic oxygenation (statement 3), per pressure gradient principles.

Why the others are wrong:

• A, B, C all include statement 1, which reverses the shunt direction (right-to-left occurs only if pulmonary hypertension develops later).

Final answer: D