Tetralogy of Fallot

1. There is a hole between the 2 lower chambers (the "ventricles").
2. The main blood vessel that brings blood to the body (the "aorta") lies over the hole between the ventricles.
3. The main blood vessel that goes to the lungs (the "pulmonary artery") is narrowed.
4. The muscle of the lower right ventricle is thickened.

These problems cause babies with this condition to have less oxygen in their blood than normal. This can make their skin, lips, fingernails, and toenails look blue.