Tetralogy of Fallot

The Cohen Children’s Heart Center is dedicated to diagnosing and treating congenital heart disease of newborns, children, teens and adults with congenital heart disease, as well as in utero. Our team of nationally recognized surgeons, cardiologists and other health care professionals has the expertise to diagnose and treat both simple and complex heart conditions, including tetralogy of Fallot (ToF).

ToF is a complex form of congenital heart disease that changes the normal flow of blood through the heart. It is the most common cyanotic condition in childhood. This is usually detected early in life when a baby’s oxygen levels are noticed to be a bit low, or by a doctor hearing a heart murmur. Because not enough blood is pumped to the lungs to be oxygenated, oxygen-poor blood flows to the body. Four main heart defects are associated with this disease:

• Ventricular septal defect (VSD), a hole in the wall (septum) between the right and left lower chambers (ventricles) of the heart.
• Override of the aorta over the VSD, a defect in which the blood vessel to the body (aorta) is positioned over the VSD, rather than over the left ventricle.
• Right ventricular outflow tract obstruction (pulmonary stenosis), a defect in which there is blockage to flow leaving the right sided pumping chamber and going to the lungs.
• Right ventricular hypertrophy, a condition in which the heart muscle is thickened due to the pressures in the right sided pumping chamber being high.

The cause of tetralogy of Fallot is not always known, although heredity may play a role. It is commonly seen in genetic disorders such as Down syndrome or DiGeorge syndrome (22q11 gene deletion).

The amount of blood flow blocked from the right ventricle varies in each case of tetralogy of Fallot. This can cause:

• Heart murmurs
• Cyanosis (bluish discoloration of the skin caused by lack of oxygen in the bloodstream)
• “Tet spells," which occur when there is more blockage to the blood that goes to the lungs, and the oxygen level in the blood suddenly drops. The infant may show signs such as:
  • Difficulty breathing (hard or deep breathing)
  • Becoming very tired and limp
  • Not responding to a parent's voice or touch
  • Tiring easily
  • Becoming very fussy
  • Fainting

When examining your baby for tetralogy of Fallot, a pediatric cardiologist will perform a physical exam that includes listening to the heart with a stethoscope. The following tests may also be used to diagnose the defect:

• Pulse oximetry (using a sensor attached to a finger or toe to measure blood oxygen)
• EKG (electrocardiogram)
• Chest X-ray
• Echocardiography (echo)
• Cardiac catheterization and interventions such as balloon valvuloplasty

Treatment of tetralogy of Fallot usually requires at least one open-heart surgery before the first year of life. Most children after repair of tetralogy of Fallot should do very well, but they will need lifelong surveillance by a cardiologist to monitor for problems such as heart rhythm problems (arrhythmia), valve leakage, exercise intolerance and reduced right ventricular function.

After surgery, patients often have residual issues, including:

• Pulmonary valve regurgitation or leakage
• Reduced right ventricular function
• Exercise intolerance
• Arrhythmia

Periodic assessment is necessary to assess the health of the right ventricle. Later on in life, some patients may require a pulmonary valve replacement. While usually performed surgically, pulmonary valve placement is becoming available in the cardiac catheterization laboratory by deployment of stent that has a valve within it.