What is tetralogy of Fallot and which heart abnormalities occur in the condition?

Tetralogy of Fallot is a congenital heart defect characterized by a specific combination of four structural abnormalities that disrupt normal blood flow, often leading to cyanosis, or "blue baby" syndrome.1

The condition involves the following four heart abnormalities:

• Ventricular septal defect: A hole in the partition that separates the heart's lower chambers.1
• Pulmonary stenosis: A narrowing of the opening to the pulmonary artery, which restricts blood flow to the lungs.1
• Overriding aorta: The aorta is displaced and dilated, positioned over the ventricular septal defect rather than originating solely from the left ventricle.1
• Right ventricular hypertrophy: The muscle of the right ventricle becomes thickened due to the increased workload required to pump blood through the obstructed pulmonary valve.1

These defects cause deoxygenated blood to bypass the lungs and enter the systemic circulation, resulting in symptoms such as hypoxic spells and digital clubbing. Surgical intervention is the standard approach to correct these structural issues.1