Understanding Tetralogy of Fallot


Tetralogy of Fallot is birth defect that changes normal blood flow through a baby’s heart.

A healthy heart has four chambers: the right atrium and right ventricle, and the left atrium and left ventricle.

After delivering oxygen to the body, oxygen-poor blood flows into the right atrium.

When the right atrium contracts, it loads blood into the relaxed right ventricle.

Then, the right ventricle contracts, sending blood to the lungs through the pulmonary artery.

The blood picks up oxygen in the lungs, then returns to the left atrium.

The left atrium contracts, filling the relaxed left ventricle with blood.

And, the left ventricle contracts to pump and deliver oxygen-rich blood to the body through the aorta.

Tetralogy of Fallot is a birth defect made up of four problems with the heart and its blood vessels.

A ventricular septal defect, or VSD, is a hole in the wall between the two ventricles.

The hole allows oxygen-rich blood to mix with oxygen-poor blood.

An overriding aorta means the aorta is shifted slightly from its usual location on the heart. It sits right over the ventricular septal defect.

This allows blood from both ventricles to flow through the aorta. As a result, some oxygen-poor blood may flow to the body.

Pulmonary stenosis means that the main pulmonary artery is narrowed. And, the pulmonary valve doesn’t open all the way.

As a result of the narrowing, less blood reaches the lungs.

Right ventricular hypertrophy means the wall of the right ventricle is thicker than normal.

This is thought to happen in response to blood flow through the ventricular septal defect, and from having to work harder to pump blood through the narrowed pulmonary artery which results in increased blood pressure.

Together, these four problems may prevent enough oxygen from reaching the baby’s body.

This may result in episodes of a condition called cyanosis, or “blue baby.” In this condition, the baby’s skin, lips, and fingernails may have a bluish tint.

To find out more about more about tetralogy of Fallot, talk to your healthcare provider.