The Tetralogy of Fallot is, as its name suggests, a combination of four congenital heart defects. These defects are:
- A ventricular septal defect (VSD), or a hole in the wall between the two lower chambers―or ventricles―of the heart.
- Pulmonary stenosis, a narrowing of the pulmonary valve and the main pulmonary artery.
- An enlarged aortic valve that seems to open from both ventricles, rather than from the left ventricle only. The aortic valve sits directly on top of the VSD; this condition is sometimes referred to as an “overriding aorta.”
- Ventricular hypertrophy, where the wall of the right ventricle is thicker than normal.
Usually, the Tetralogy of Fallot is diagnosed during the first few days of life, but depending on the severity of the defects, it is sometimes not diagnosed until much later, even into adulthood. As a cyanotic heart defect, the Tetralogy of Fallot causes children to turn blue from lack of oxygen. The incidence rate in the United States is approximately 1 in every 2518 babies.
Infants and children with the Tetralogy of Fallot may develop “tet spells.” During these spells, the child becomes blue, short of breath, and may lose consciousness.
Before open-heart surgery became possible, children were treated with a palliative procedure that formed an anastomosis between the subclavian and pulmonary artery (the “Blalock–Taussig shunt.”) In 1954, C. Walt Lillhei performed the first procedure to fully correct the Tetralogy of Fallot.