Which congenital heart defect is associated with cyanosis and oligemia?

Tetralogy of Fallot is a congenital heart defect characterized by a combination of four heart anomalies: ventricular septal defect, pulmonic stenosis, right ventricular hypertrophy, and an overriding aorta. This condition leads to decreased blood flow to the lungs (which is termed oligemia) due to the right ventricular outflow obstruction (pulmonic stenosis) and the presence of the ventricular septal defect allows deoxygenated blood to mix with oxygenated blood. As a result, this mixture causes cyanosis, a condition where there is insufficient oxygenation of the blood, leading to a bluish discoloration of the skin and mucous membranes.

In contrast, other congenital heart defects listed do not consistently present with both cyanosis and oligemia in the same way as Tetralogy of Fallot. For instance, transposition of the great arteries typically results in severe cyanosis from birth, but patients may not exhibit oligemia since there is usually adequate blood flow through the systemic and pulmonary circulations, depending on the presence of a shunt. Atrial septal defects and ventricular septal defects may lead to increased pulmonary blood flow, causing a lack of cyanosis, and do not generally exhibit oligemia. Therefore, Tetralogy of