What are the four defects associated with Tetralogy of Fallot?

Tetralogy of Fallot is a congenital heart defect characterized by a combination of four specific structural abnormalities of the heart, which lead to inadequate oxygenation of blood and various clinical symptoms. The correct set of four defects includes a ventricular septal defect, pulmonary (or pulmonic) stenosis, an overriding aorta, and right ventricular hypertrophy.

The ventricular septal defect is a hole in the wall that separates the two lower chambers of the heart (ventricles), allowing oxygen-poor blood to mix with oxygen-rich blood. Pulmonary stenosis refers to the narrowing of the outflow pathway from the right ventricle to the pulmonary artery, making it difficult for the heart to pump blood to the lungs. An overriding aorta means that the aorta is positioned directly over the ventricular septal defect, straddling both ventricles instead of rising solely from the left ventricle. Lastly, right ventricular hypertrophy occurs as a compensatory response to the increased workload on the right ventricle caused by the pulmonary stenosis.

This understanding of the defects is critical for recognizing the implications on blood flow and oxygenation in patients with Tetralogy of Fallot, as well as for guiding management and treatment strategies.