**Question:** NOT a feature of Tetralogy of Fallot among the following

A. Pulmonary stenosis
B. Pulmonary atresia
C. Ventricular septal defect (VSD)
D. ASD (Atrial Septal Defect)

**Core Concept:**

Tetralogy of Fallot (ToF) is a congenital heart defect characterized by four primary abnormalities: 1) Right ventricular hypertrophy, 2) Pulmonary stenosis, 3) A large VSD, and 4) Abnormal connection of the pulmonary artery to the right ventricle (Venous-to-arterial shunting).

**Why the Correct Answer is Right:**

Option D (Atrial Septal Defect, ASD) is incorrect because ASD is a type of congenital heart defect where there is a hole in the wall (septum) separating the two upper chambers (atria) of the heart. It is not a component of Tetralogy of Fallot.

**Why Each Wrong Option is Incorrect:**

Option A (Pulmonary stenosis) is incorrect because pulmonary stenosis is a narrowing of the pulmonary valve, restricting blood flow from the right ventricle to the pulmonary artery. While it is a feature of Tetralogy of Fallot, it is not exclusive to this condition and can also be present in other congenital heart defects.

Option B (Pulmonary atresia) is incorrect because pulmonary atresia refers to the absence of the pulmonary valve and arteries. This is a separate condition from Tetralogy of Fallot, which is characterized by the presence of pulmonary stenosis and other features mentioned.

Option C (Ventricular septal defect, VSD) is incorrect because an atrial septal defect is a hole in the wall separating the two lower chambers (ventricles) of the heart. A VSD is a component of Tetralogy of Fallot, not a feature exclusive to ToF.

**Clinical Pearl:**

Tetralogy of Fallot is a complex congenital heart defect with distinct components. Understanding these features is crucial for accurate diagnosis and management of patients with this condition. ASD, VSD, and PA are not exclusive to Tetralogy of Fallot, while pulmonary stenosis is a feature of ToF but can also be present in other congenital heart defects.