**Question:** All of the following are true regarding Tetralogy of Fallot except –

A. Pulmonary stenosis is a component of Tetralogy of Fallot.
B. Aortopulmonary collateral arteries are present in Tetralogy of Fallot.
C. Pulmonary atresia is a feature of Tetralogy of Fallot.
D. The ventricular septal defect (VSD) in Tetralogy of Fallot is always large.

**Correct Answer:** C. Pulmonary atresia is a feature of Tetralogy of Fallot.

**Core Concept:** Tetralogy of Fallot is a congenital heart defect characterized by the presence of four primary abnormalities: pulmonary stenosis (obstruction in the pulmonary valve), VSD (ventricular septal defect), overriding aorta, and a large right ventricular outflow tract.

**Why the Correct Answer is Right:** Pulmonary atresia refers to the complete absence of the pulmonary valve and the main pulmonary artery. In Tetralogy of Fallot, there is pulmonary stenosis but not complete absence of the pulmonary valve. Therefore, pulmonary atresia is not a feature of Tetralogy of Fallot.

**Why Each Wrong Option is Incorrect:**

A. Pulmonary stenosis is a component of Tetralogy of Fallot, which is true, as mentioned earlier.
B. Aortopulmonary collateral arteries are present in Tetralogy of Fallot, but they are not a part of the four key features of the condition.
D. The ventricular septal defect (VSD) in Tetralogy of Fallot is not necessarily large. Some cases exhibit a moderate to severe VSD, while others have a smaller VSD.

**Clinical Pearl:** Tetralogy of Fallot is a congenital heart defect that requires careful clinical assessment, as some of its features (e.g., pulmonary stenosis, overriding aorta) overlap with other congenital heart defects, and the presence of pulmonary atresia is crucial for the diagnosis. A thorough understanding of the condition and its components is essential for proper diagnosis and management of the patient.