Tetralogy of Fallot (also called "TOF") is a heart condition made up of 4 related heart problems:
- There is a hole between the 2 lower chambers (the "ventricles").
- The main blood vessel that brings blood to the body (the "aorta") lies over the hole between the ventricles.
- The main blood vessel that goes to the lungs (the "pulmonary artery") is narrowed.
- The muscle of the lower right ventricle is thickened.