TETRALOGY OF FALLOT
Tetralogy of Fallot (fah-LO) is a combination of four birth defects that together affect the structure of the heart and how blood flows through it.
Each year, 4 out of every 10,000 babies born in the United States have the condition, which was named after the French doctor who first described it in the late 1800s, Étienne Fallot. About 10% of all babies born with a heart problem have tetralogy of Fallot (TOF).
The four defects that together make up tetralogy of Fallot are:
- Ventricular septal defect (VSD), which is a hole in the septum, or wall, separating the two lower chambers, or ventricles, of the heart. The septum acts as a barrier that prevents blood from both sides of the heart from mixing together. But when there is a VSD, blood high in oxygen from the left ventricle can mix with blood low in oxygen from the right ventricle.
- Pulmonary stenosis, a narrowing or thickening of the valve that connects the right ventricle to the pulmonary artery, a blood vessel that carries low-oxygen blood from the heart to the lungs, where the blood receives more oxygen and then returns to the heart. With pulmonary stenosis, the heart has to work harder than normal to pump blood to the lungs. Often, the amount of blood reaching the lungs is below normal.
- Right ventricular hypertrophy (hi-PER-truh-fee), which is a thickening of the muscular wall of the right ventricle.
- An “overriding aorta,” which means the artery that carries high-oxygen blood to the body is out of place and arises above both ventricles, instead of just the left ventricle, as in a healthy heart. This allows some blood that is low in oxygen to flow into the aorta and out to the body, instead of to the pulmonary artery, which would normally take it to the lungs to pick up oxygen.
The combined effect of these defects is an inadequate supply of blood to the lungs, which causes blood low in oxygen to circulate to the rest of the body. This lower oxygen level causes cyanosis, which is a blue or purple tint to the skin, lips, and fingernails.
Children with tetralogy of Fallot:
- might experience dizziness, fainting, or seizures
- are at a higher risk of developing an infection of the inner layer of the heart called endocarditis
- can have an irregular heartbeat, called an arrhythmia, which with TOF is caused by elevated pressure in the right side of the heart
A child whose TOF is not repaired might need to limit his or her participation in competitive sports and other physical activities. Many infants who have surgery to correct the defect do very well, participate in normal kid activities, and live to adulthood.