What Is Tetralogy of Fallot?

Formerly known as Blue Baby Syndrome

<p>BSIP / Getty Images</p>

BSIP / Getty Images

Medically reviewed by Rafle Fernandez, MD

Tetralogy of Fallot (TOF) is a birth defect of the heart in which four conditions are happening. One, there is a hole between the heart’s pumping chambers, or the ventricles. This is called a ventricular septal defect. Two, there is some obstruction or blockage of the pulmonary valve and the pulmonary artery, which connects the heart to the lungs. This is called pulmonary stenosis. Three, the aortic valve is larger than usual, and opens from both of the heart’s ventricles instead of the left ventricle only. Four, the muscle surrounding the lower right ventricle thickens more than usual. This is called ventricular hypertrophy.

In someone without TOF, the right side of the heart pumps oxygen-poor blood to the lungs, where the lungs absorb oxygen and remove carbon dioxide. This creates oxygen-rich blood that can be sent to the left side of the heart, which sends it to arteries and the rest of the body.

In TOF, blood moves across the hole in the ventricles. The blood can then move through the aorta, sending oxygen-poor blood through the body.

Tetralogy of Fallot Symptoms

The most common symptom for people with TOF is that they often turn blue, which is called cyanosis. The areas of the body most likely to turn blue are the fingers, toes, and lips. This is such a prominent symptom that tetralogy of Fallot was referred to as Blue Baby Syndrome many years ago.

Some parts of the body may not get as much oxygen as they should. This can result in shortness of breath.

For some people with TOF, symptoms do not occur right after birth. In some cases, cyanosis can occur months after the baby is born. Research suggests the severity of cyanosis depends on how obstructed the pulmonary artery is.

Other symptoms can include clubbing of the fingers, difficulty feeding, inability to gain weight, passing out, poor development, and squatting during episodes of shortness of breath. Squatting can lead to an increase in blood flow to the lungs, allowing the body to get more oxygen.

People with TOF can live with no symptoms, but some may have problems that occur over and over. This can include a leaky heart valve, an obstruction (blockage of blood leaving the right ventricle), and heart rhythm problems.

What Causes TOF?

The cause of TOF in most children is unknown. It is the most common heart defect in children that is present at birth, and is more commonly seen in children with Down syndrome and DiGeorge syndrome. DiGeorge syndrome is a condition where a piece of a specific chromosome (chromosome 22) is deleted. This condition causes heart defects, low calcium levels, and poor immune function.

Some heart defects may be related to a person’s genes or chromosomes, while others could be related to the environment. Factors which may increase risk of TOF include excessive alcohol consumption in the birthing parent, untreated diabetes of the birthing parent, a person who gives birth over the age of 40, poor nutrition during pregnancy, and Rubella or other viral illnesses during pregnancy.


Diagnosis of TOF can occur either during pregnancy at a prenatal visit or right after a baby is born.

During Pregnancy

Tetralogy of Fallot may be diagnosed during a routine prenatal ultrasound (a tool used to view the developing embryo or fetus in utero). If the health care provider suspects TOF from the images of the ultrasound, they may order an echocardiogram to confirm the results from the ultrasound. The echocardiogram will help the healthcare provider examine blood flow and the heart’s structure.

After Birth

Tetralogy of Fallot can be diagnosed after the baby is born if no tests are done during pregnancy. This is usually done if the baby turns blue when crying or feeding. This is called a “tet spell.” The healthcare provider may also suspect TOF during a physical exam if they notice the skin has a bluish color or if they hear a heart murmur.

Tetralogy of Fallot in Adults

Most people are diagnosed with TOF as an infant or young child. Tetralogy of Fallot that is left untreated can be seen in adults, as they may experience certain areas of the body turning blue. Treatment options can look similar for children and adults.

Treatments for Tetralogy of Fallot

In TOF, the goal for treatment is to minimize symptoms and live as normal a life as possible. The most important part about living with a heart defect is to see a cardiologist (a medical doctor who specializes in the heart) regularly and seek treatment options as necessary.

Treatment options for TOF include two types of surgery: a shunt operation or a complete repair.

  • The shunt operation provides temporary improvement for the problem. A shunt is sewn between the aorta or a body artery and the pulmonary artery to aid in more blood flow to the lungs. The shunt is oftentimes done first until a complete repair of the heart can be done, in which case the shunt will be removed.

  • In a complete repair, the defect in the ventricles is closed with a patch. This should relieve the obstruction of blood flow going to the lungs. Sometimes a tube with a valve in it is surgically placed between the right ventricle and the pulmonary artery, called a Rastelli repair. In some cases, patients may have both of these surgeries in their lifetime.


Because there is no proven research explaining what causes TOF, there is no known way to prevent the condition. Some risk factors for TOF are related to the birthing parent’s dietary habits. It is important to see a healthcare provider during pregnancy to discuss any potential risk factors.

For those who do have heart surgery, physical activity exercise should be limited if shortness of breath is a recurring issue. Check with a cardiologist about physical limitations and recommendations for strenuous activities.

Related Conditions

Children diagnosed with TOF are at higher risk for endocarditis (inflammation of the lining around the heart’s chamber and valves). Some children may also need to take antibiotics before certain dental procedures. This can help to prevent endocarditis.

Surgery to open up the pulmonary valve can lead to complications, including a leaky pulmonary valve. Your healthcare provider may suggest another surgery to resolve this problem. Obstructed pathways can also be a problem as the person with TOF grows. Another surgery to replace the pulmonary valve may be needed later if these conditions occur.

In addition to these conditions, people with TOF may experience weakened function of the right-side of the heart or an abnormal heart rhythm. Pregnant people who have had a repair for TOF should be monitored by a cardiologist for treatment options in case there are complications during pregnancy or while giving birth.

Living With TOF

Tetralogy of Fallot is rare, but it is also the most common type of heart disease at birth. If you or your child have been diagnosed with TOF you will need to consult with your doctor following surgical repair for guidelines.

Even if surgical repair of the heart goes well, regular follow up with a cardiologist is recommended. The cardiologist should be someone who specializes in congenital heart defects. Even after your child becomes an adult, they will still need to follow up with a cardiologist regularly. In addition to regular follow up with a cardiologist, you may need medications and more surgeries if any complications from TOF occur.

Frequently Asked Questions

Can kids with TOF play sports?

Children who have had surgery to fix the defect that causes TOF can usually participate in any activity as a child without TOF can. Children who haven't had the surgery will likely have worsening cyanosis over time and should generally avoid over-exerting themselves with physical activity.

What is the life expectancy of someone with tetralogy of Fallot?

Life expectancy of people with TOF following complete repair is very good. A prominent 2019 study found the following survival rates:

  • 1-year: 98.6%

  • 5-year: 97.8%

  • 10-year: 97.1%

  • 20-year: 95.5%

  • 25-year: 94.5%

Who is the oldest person with the tetralogy of Fallot?

One of the oldest reported people with unoperated tetralogy of Fallot was documented to be 87-years-old in 2009.

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