Tetralogy of Fallot

ToF is the most common cyanotic (blue) heart defect. About 5 out of every 10,000 babies are born with ToF.

ToF develops in early pregnancy when the heart begins to form. Normally, the heart divides into two equal parts. In ToF, the heart divides unevenly, creating all four heart defects.

We do not know exactly what causes ToF. Some people have a genetic mutation (or error) that causes it, such as a small missing piece of a chromosome. Babies with specific syndromes, such as Down syndrome or DiGeorge syndrome, have a higher risk of ToF. More research is needed to understand the role of genes and the environment in causing ToF.

People born with ToF do well over time. Many are now in their 60s, 70s and even 80s.

The Blalock-Taussig-Thomas (BTT) shunt, a surgery, was first performed on babies with ToF in the 1940s. This surgery increased blood flow to the lungs and helped babies get enough oxygen to their bodies. It let them survive until open-heart surgery was developed in 1954.

A surgical repair does not mean that your heart is permanently fixed. You can develop new heart problems as you age. It is important that you stay in the care of an adult congenital heart disease (ACHD) specialist throughout your life. Talk to your doctor regularly so changes in your heart can be detected early, which helps prevent permanent damage.

The most common problem in adults with ToF is a leaking pulmonary valve, also called pulmonary regurgitation or PR. During the repair, the doctor stretches the pulmonary valve to open it. This almost always makes the valve leak. As you age, the leak can get worse.

• It makes the right side of your heart get bigger, affecting your heart’s ability to pump. When your heart does not function as well, it can eventually cause heart failure.
• It increases the chance of developing a dangerously fast heartbeat in the right ventricle, called ventricular tachycardia or VT. If not treated, VT can lead to sudden death.
• It can cause rhythm problems in the upper chambers, or atria.
• The tricuspid valve may leak, called tricuspid regurgitation. If both the tricuspid and pulmonary valves leak, the right ventricle will also grow.
• It can make your aorta just above the aortic valve too large. This may cause a leak to develop in the aortic valve, called aortic regurgitation.

Sometimes there are few or no symptoms of a leaky valve. If you notice any of these symptoms, let your ACHD cardiologist know:
• Rhythm problems, such as a fast heartbeat or feeling your heart flutter.
• Less energy.
• Shortness of breath on effort.
• Swelling in your leg and/or belly.

Your ACHD care team has tools to determine how severe the leak is. They might even hear the leak by listening to your heart.

Your doctor may use these tests to look for a leaky valve:
• Echocardiogram (ECHO)
• EKG or ECG
• Cardiac CT scan
• Exercise test
• Transesophageal echo (TEE)
• Cardiac MRI
• Cardiac catheterization

If you need a pulmonary valve replacement (PVR), talk with your doctor about whether your valve should be replaced with surgery or by catheter.

There are two kinds of surgical valves. Tissue valves come from human cadavers (called homograft valves) or from pig or cow heart tissue (called heterograft valves). Mechanical valves are rarely used for PVR because they require ongoing treatment with a blood thinner called warfarin.

Today, many people with ToF can have catheter-based PVR, avoiding the need for heart surgery. Your ACHD cardiologist can advise. Valves used in these procedures are like tissue valves that are implanted surgically.

The right time to replace a pulmonary valve varies from person to person. Your ACHD doctor will advise you based on your symptoms, the results of heart tests, and the most recent ACHD care guidelines. Because valve replacements do not last forever, your doctor might want to wait as long as possible without hurting your heart.

People with ToF can develop health problems that affect people without CHD, such as high blood pressure, high cholesterol, obesity, and sleep apnea. Your ACHD doctor can assess and treat these concerns.

Many women with ToF can safely go through pregnancy and delivery. If you are thinking about becoming pregnant, start by talking with your ACHD cardiologist. Make sure you do not need changes in your medication or need a valve replacement before becoming pregnant.

You should also talk with an obstetrician who specializes in high-risk pregnancies. Your ACHD care team and your obstetrician should work together to develop a plan to care for your heart during your pregnancy and delivery.

There is a small but increased chance of CHD in babies born to parents with any CHD, including ToF. But most people with ToF have babies without heart problems. A genetic disorder, DiGeorge syndrome (22q11.2 deletion syndrome), has been linked to ToF. If you have ToF and want to have a baby, ask to be screened for this disorder.

ToF is a moderately complex form of congenital heart disease. You should receive lifelong care from an ACHD board certified doctor, preferably at an ACHA ACHD Accredited Program. Choosing the right doctor and ACHD program to manage your adult congenital heart disease is crucial. The ACHD Clinic Directory offers information on ACHD Board Certified providers certified by the American Board of Internal Medicine (ABIM) and ACHA ACHD Accredited Centers.