Tetralogy of Fallot (TOF or “TET”) is a combination of several heart defects that are present at birth (congenital). These occur when the fetal heart doesn’t develop properly during the first two months of pregnancy. Tetralogy of Fallot decreases oxygen in the bloodstream, often causing babies to appear blue (cyanotic) or become fussy or lethargic.

The combination of congenital heart defects that impact children with Tetralogy of Fallot include:

1. Ventricular septal defect (VSD): A VSD is a hole between the left and right side of the heart (known as ventricles). This allows large amounts of oxygen-poor blood from the right ventricle to pass into the left ventricle without going to the lungs. The body is then supplied with blood that does not have enough oxygen.
2. Narrowing of the pulmonary valve: The pulmonary valve is the entrance to the pulmonary artery found in the right ventricle. Because of the narrowing of the valve, the right ventricle needs to work harder to get blood into the lungs.
3. Overriding aorta: The aorta is shifted toward the right side of the heart so that it sits over the ventricular septal defect. Because of this placement, it will pick up more oxygen-poor blood that is normally found in the right ventricle.
4. Right ventricle enlargement: The size of the right ventricle is bigger than normal. This is because of the increased effort required to get blood through the narrowed pulmonary valve.

In Tetralogy of Fallot, blood flow within the heart varies. It is also largely dependent on the size of the ventricular septal defect and how severe the block in the right ventricle is.

Specific treatment for tetralogy of Fallot will be determined by your child's physician based on:

• Your child's age, overall health and medical history
• Extent of the condition
• Your child's tolerance for specific medications, procedures or therapies
• Expectations for the course of the condition
• Your opinion or preference

Tetralogy of Fallot is treated by surgical repair. A team of cardiac surgeons performs the surgery, usually before an infant is 1 year old. In many cases, the repair is made at around 6 months of age or earlier. Repairing the heart defects will allow oxygen-poor (blue) blood to travel its normal route through the pulmonary artery to receive oxygen.

The operation is performed under general anesthesia and involves the following:

• The ventricular septal defect is closed with a patch.
• The obstructed pathway between the right ventricle and the pulmonary artery is opened and enlarged with a patch.
• If the pulmonary valve is small, it may be opened as well.