Which condition is listed among acyanotic conditions in the material?

Which condition is listed among acyanotic conditions in the material?

• A. Tetralogy of Fallot
• B. Transposition of the great arteries
• C. Patent ductus arteriosus
• D. Tricuspid atresia

Answer: (C)

Acyanotic conditions are those in which oxygen-rich blood still reaches the body and systemic oxygen saturation remains normal, at least early on. Patent ductus arteriosus fits this pattern because it creates a left-to-right shunt from the aorta to the pulmonary artery. This increases pulmonary blood flow but does not reduce the oxygen content of blood reaching the body's tissues, so the infant is not cyanotic. Over time, if the shunt becomes very large and pulmonary vascular resistance falls, reversal can occur (Eisenmenger syndrome), leading to cyanosis, but classically PDA is considered acyanotic. The other conditions listed are cyanotic because they either cause right-to-left shunting or parallel circulations that deliver less oxygenated blood to the body, resulting in a blue tint: Tetralogy of Fallot involves a right-to-left shunt; transposition of the great arteries creates separate, parallel circulations; tricuspid atresia leads to mixing with reduced systemic oxygenation.

Acyanotic conditions are those in which oxygen-rich blood still reaches the body and systemic oxygen saturation remains normal, at least early on. Patent ductus arteriosus fits this pattern because it creates a left-to-right shunt from the aorta to the pulmonary artery. This increases pulmonary blood flow but does not reduce the oxygen content of blood reaching the body's tissues, so the infant is not cyanotic. Over time, if the shunt becomes very large and pulmonary vascular resistance falls, reversal can occur (Eisenmenger syndrome), leading to cyanosis, but classically PDA is considered acyanotic.

The other conditions listed are cyanotic because they either cause right-to-left shunting or parallel circulations that deliver less oxygenated blood to the body, resulting in a blue tint: Tetralogy of Fallot involves a right-to-left shunt; transposition of the great arteries creates separate, parallel circulations; tricuspid atresia leads to mixing with reduced systemic oxygenation.