Tetralogy of Fallot (TOF)

Tetralogy of Fallot is 4 congenital heart defects. This means that your child is born with them. These 4 problems occur together (tetralogy refers to 4). They are:
  1. Narrowing (stenosis) of the pulmonary artery. The pulmonary artery is a blood vessel. It carries blood from the heart to the lungs for oxygen.
  2. Ventricular septal defect. This is an opening in the wall between the two lower chambers of the heart (right and left ventricles). 
  3. Overriding aorta. The artery that carries oxygen-rich blood to the body (aorta) is shifted toward the right side of the heart. It should be on the left side. In this condition, the aorta sits over the ventricular septal defect.
  4. Enlarged right ventricle. The right lower chamber of the heart (ventricle) is bigger than normal.

In a healthy heart, oxygen-poor (blue) blood returns to the right chamber of the heart (atrium) from the body. Next, it travels to the right ventricle of the heart. Then it’s pumped through the pulmonary artery into the lungs for oxygen. Oxygen-rich (red) blood comes back to the left chamber of the heart from the lungs. Then it passes into the left ventricle of the heart. Finally, it’s pumped through the aorta to the body.

In a child with tetralogy of Fallot, the following can happen:

  • Some children may only have slightly lower than normal oxygen levels in their blood. These children don’t usually have bluish skin (cyanosis).
  • Some children will have low oxygen levels in their blood. These children have bluish skin. This is from the low oxygen levels in their blood.