Guide to Tetralogy of Fallot

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Tetralogy of Fallot is a rare but serious birth defect that compromises blood flow from the heart to the rest of the body. This can lead to poor oxygen levels, delayed growth, and other complications. Babies with this condition will require surgery shortly after birth.

Key Facts

Tetralogy of Fallot is composed of four separate heart defects: a hole between the left and right ventricles, a narrow pulmonary artery, a thickening of the right ventricle, and a misaligned aorta.
These defects compromise how well the heart can pump blood to the rest of the body and how well blood gets oxygenated by the lungs.
Infants are usually diagnosed shortly after birth. Corrective surgery is required to fix the four defects to ensure the heart can function normally.

Causes

Tetralogy of Fallot occurs when the heart’s structures do not form correctly during fetal development. The exact reasons for this are still unknown, though likely it is a combination of risk factors such as:

Drinking alcohol while pregnant
Poor nutrition while pregnant
Contracting a virus while pregnant
A parent with tetralogy of Fallot
Genetic conditions such as Down syndrome or DiGeorge syndrome
A mother older than 40

Tetralogy of Fallot specifically refers to when the following four defects are present at once:

Ventricular septal defect: An opening between the heart’s two lower chambers, known as the right and left ventricles. Because blood pressure is higher in the left ventricle, more blood flows into the right ventricle, leading to unequal distribution of blood flow to the body.
Pulmonary stenosis: This occurs when the heart valve that allows blood to move from the heart to the lungs is too narrow and restricts flow.
Right ventricular hypertrophy: This refers to a thickening in the muscular wall of the heart’s right ventricle; thickening of the heart chamber walls can impede the heart’s ability to pump blood.
Overriding aorta: This is a defect in which the aorta, the body’s major artery, is positioned incorrectly. As a result, oxygen-rich and oxygen-poor blood get mixed, causing the body to receive less oxygen than it should from the heart.

Symptoms

The severity of tetralogy of Fallot symptoms will depend on a number of factors, such as the amount of blood flow being blocked and the presence of any additional defects. Common symptoms include:

Blue skin, lips, or fingernails (cyanosis)
Chronic exhaustion
Fainting
Heart murmur
Irregular heartbeat
Irritability
Poor weight gain and/or development
Rapid breathing
Rounded nail beds (clubbing)
Sudden drop in oxygen levels (tet spell)

Diagnosis

Tetralogy of Fallot can be diagnosed either before birth or shortly after. During pregnancy, a diagnosis may be made using two methods:

Ultrasound: This test uses sound waves to create a picture of the fetus in the womb. A routine part of pregnancy exams, it is typically the first way tetralogy of Fallot is detected.
Fetal echocardiogram: This test provides more detailed images of the fetus’s heart. It can show doctors whether there are defects in the heart’s structure.

More frequently, tetralogy of Fallot is diagnosed shortly after birth, when a nurse or doctor notices signs of the condition, such as cyanosis (blue skin, lips, or fingernails) or a heart murmur, during a physical exam. There are a number of methods to confirm the diagnosis, including:

Cardiac catheterization: This procedure is used to gain vital information about how various parts of the heart are functioning. It involves inserting a thin, flexible tube called a catheter into a blood vessel and up into the heart so different measurements can be taken.
Chest X-ray: This test creates a detailed picture of the heart and lungs, allowing doctors to check for signs of disease.
Echocardiogram: This technique uses sound waves to produce an image of the heart. Doctors can use it to see the heart beating and pumping blood while they look for defects.
Electrocardiogram: This test measures the electrical activity of the heart. Sensors called electrodes are attached to the patient’s arms, legs, and chest to measure how well the heart is beating.
Pulse oximetry: This simple, noninvasive test measures oxygen levels in the blood. A small sensor is placed on the fingertip to track how well light waves are absorbed. This information is then used to determine how much oxygen is present.

Treatment

Corrective heart surgery is the only viable treatment option for tetralogy of Fallot, although some medications may be used alongside surgery. While the exact surgical procedures will depend on the number and severity of defects, open heart surgery is typically required within the baby’s first year. There are three surgical methods to treat the condition:

Intracardiac surgical repair: During this operation, the surgeon will patch the ventricular septal defect to close the opening between the heart’s ventricles and widen the narrowed pulmonary valve or artery.
Temporary shunt surgery: During this procedure, a shunt, a small tube usually made of synthetic material, is sewn between the aorta and the pulmonary artery so that more blood flows to the lungs. The shunt is removed later on during intracardiac surgical repair.
Patent ductus arteriosus (PDA) stent: If the heart cannot deliver blood to the lungs due to a defect in the pulmonary valve, it may be necessary to add a stent, an expandable mesh tube, to open a blood vessel called the patent ductus arteriosus, or PDA. The PDA helps deliver blood during development but closes after birth. By reopening the PDA, some blood flow is restored to the lungs. The defect is then fixed during intracardiac surgical repair at a later time.

Outlook

Advances in surgical techniques and technology mean that the vast majority of children who undergo corrective surgery for tetralogy of Fallot defects go on to lead normal, healthy lives. One study found the 10-year survival rate was 95.8% and the 30-year was 90.5%.

Possible Complications

Anyone who receives surgery for tetralogy of Fallot will need to have regular follow-ups to reduce the risk of developing additional complications, such as:

Elevated heart rhythm: Also known as junctional tachycardia, this condition will usually disappear and can be treated with medication or a temporary pacemaker.
Heart block: This condition can develop if the heart’s electrical conduction system is injured, causing the heart to slow down. It will typically improve on its own.
Insufficient pulmonary valve: In some cases, the valve that controls the flow of blood from the right ventricle to the aorta may not function correctly, making the heart work harder to pump blood. If the valve cannot be repaired, it may need to be replaced.
Narrowing of blood vessels: Some patients may redevelop narrow blood vessels, which can lead to elevated blood pressure. Surgery may be needed to reopen these blood vessels.

Next Steps

If your child has been diagnosed with tetralogy of Fallot, the Congenital Heart Center can help. Our team can offer personalized treatment plans delivered with a level of quality that could only come from one of the most experienced programs in the country.

Call us at 212-305-2688 or use our online form to schedule an appointment.