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 healthcare professionals has the expertise to diagnose and treat both simple and complex heart conditions, including tetralogy of Fallot (ToF).
Tetralogy of Fallot (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. 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 on the septum between the right and left ventricles (lower chambers) of the heart. These are usually detected by a doctor hearing a heart murmur.
- Override of the aorta over the VSD, a defect in which the aorta is positioned over the VSD, rather than over the left ventricle.
- Right ventricular outflow tract obstruction (pulmonary stenosis), a defect in which the right ventricular outflow tract is blocked.
- Right ventricular hypertrophy, a condition in which the heart muscle is thickened due to obstruction of blood flow to the lung.
Causes & risk factors
The cause of tetralogy of Fallot is not always known, although heredity may play a role. It is expressed 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 the oxygen level in the blood suddenly drops. These are:
- Difficulty breathing
- Becoming very tired and limp
- Not responding to a parent's voice or touch
- Tiring easily while feeding
- Slow weight gain
- Becoming very fussy
- Clubbing (skin or bone around the fingertips becomes enlarged)
Diagnosis & testing
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. Lifelong surveillance is required due to the increased incidence of arrhythmia, 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
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 the Melody™ valve.