Which finding would you expect in left-to-right shunts?

Which finding would you expect in left-to-right shunts?

• A. Increased pulmonary blood flow
• B. Cyanosis at birth
• C. Decreased pulmonary vascular resistance
• D. Right-to-left shunt at rest

Answer: (A)

Left-to-right shunts increase the amount of blood flowing through the lungs because oxygenated blood from the left heart is redirected back into the pulmonary circulation. This extra flow causes increased pulmonary blood flow and volume, which is the hallmark finding. Cyanosis at birth wouldn’t be expected because systemic oxygenation remains preserved unless the shunt later reverses (Eisenmenger syndrome). Decreased pulmonary vascular resistance is a normal postnatal change that helps enable left-to-right shunting but isn’t a direct result of the shunt itself. A right-to-left shunt at rest would cause hypoxemia and cyanosis, not the pattern seen with left-to-right shunts.

Left-to-right shunts increase the amount of blood flowing through the lungs because oxygenated blood from the left heart is redirected back into the pulmonary circulation. This extra flow causes increased pulmonary blood flow and volume, which is the hallmark finding. Cyanosis at birth wouldn’t be expected because systemic oxygenation remains preserved unless the shunt later reverses (Eisenmenger syndrome). Decreased pulmonary vascular resistance is a normal postnatal change that helps enable left-to-right shunting but isn’t a direct result of the shunt itself. A right-to-left shunt at rest would cause hypoxemia and cyanosis, not the pattern seen with left-to-right shunts.