Tetralogy of Fallot (TOF)


This heart problem is present at birth. It's a combination of four heart defects that change the way blood flows through the heart and to the lungs. As a result, blood can't get all the oxygen it needs to supply the body's cells.

The Four Defects

The first of four problems is a ventricular septal defect. We call it a "VSD." It's a hole in the wall that divides the heart's two lower chambers (the ventricles). The second is called "pulmonary stenosis." It's a narrowing of the valve and the vessel that carries blood from the right ventricle to the lungs. The third is called "right ventricular hypertrophy." That's a thickening of the muscle of the right ventricle. The fourth defect is called an "overriding aorta." With this, the aorta (the main vessel that carries blood from the heart to the body) is slightly out of place.

Causes and Risk Factors

We don't know why this condition develops. Genes may play a role. It may be linked to certain viruses that can affect a baby who is still in the womb. Expectant mothers who are older than 40, who have diabetes, who drink alcohol or don't eat a proper diet while pregnant have a higher risk for having a baby with this condition.


A baby with TOF has a low level of oxygen in the blood. This causes the skin, lips and fingernails to have a bluish tint. The baby may tire easily when it feeds, and may have a heart murmur.


Tetralogy of Fallot is treated with surgery. The repair can be done soon after birth, or your doctor may recommend waiting until the baby is stronger. If it's done later, a temporary surgery can be performed to improve oxygen levels in the blood. Medications may help, too. Your healthcare provider can create a plan that's right for you.