Which of the following is not a cyanotic heart anomaly?

Atrial septal defect (ASD) is considered an acyanotic heart defect rather than a cyanotic one. This distinction is based on the nature of blood flow and oxygenation within the heart. In an ASD, there is an opening between the left and right atria, allowing oxygen-rich blood from the left atrium to mix with oxygen-poor blood in the right atrium. This typically does not lead to significant amounts of deoxygenated blood flowing into the systemic circulation, so patients with an ASD usually do not exhibit the bluish discoloration (cyanosis) characteristic of cyanotic heart anomalies.

Cyanotic heart defects, on the other hand, involve abnormal blood flow that allows deoxygenated blood to enter the systemic circulation, thus leading to cyanosis. Conditions like Tetralogy of Fallot, pulmonary atresia, and hypoplastic left heart syndrome all lead to such mixing, resulting in a lack of oxygenation in the blood that can cause the characteristic cyanosis.