Tetralogy of Fallot

Tetralogy of Fallot (TOF) is a complex but rare type of heart defect you are born with. A baby born with TOF has four different heart problems.

If you or a loved one has recently been diagnosed with TOF, Banner Health is here to help. We’ll explain more about this heart defect and how it affects daily life.

What is tetralogy of Fallot?

Tetralogy of Fallot (TOF) is a congenital heart defect that some children are born with. It is a group of four related symptoms or problems that change how blood flows to the lungs and the heart.

These defects are:

• Ventricular septal defect (VSD): A hole in the wall (septum) between the heart’s lower chambers (ventricles).
• Pulmonary stenosis: A narrowing of the pulmonary valve or artery, which reduces blood flow from the heart to the lungs.
• Overriding aorta: The aorta (the major artery that carries blood to the body) is shifted and lies over a hole (VSD) in the lower chambers. 
• Right ventricular hypertrophy: The muscular wall of the heart's right ventricle is thicker than normal. 

Normally, blood travels a specific path through the heart with every heartbeat. In a child with TOF, some blood that doesn’t have enough oxygen in it (oxygen-poor or low-oxygen blood) can go into the aorta and out to the body. This low-oxygen blood then goes to the rest of the body and not enough oxygen reaches the body tissues.

Babies born with TOF often have blue or gray skin color (cyanosis) due to low oxygen levels.

Causes of tetralogy of Fallot

Children are born with TOFs. They happen when the baby’s heart grows during pregnancy.

While the exact cause isn’t always clear, some heart defects may be passed down in families (genetic/inherited). Some things may increase the risk of a baby having TOF. Other risk factors include: 

• Drinking alcohol or smoking during pregnancy
• Eating poorly during pregnancy
• Having a virus during pregnancy, like German measles (rubella)
• Baby has another genetic condition, like Down syndrome or DiGeorge syndrome

Learn more about the causes and risk factors of congenital heart defects (CHDs). 

Symptoms of tetralogy of Fallot

Babies born with TOF may have a bluish tint to their skin, lips and fingernails because their blood lacks oxygen. Without treatment, they may develop tetralogy spells or “tet spells” when their oxygen levels drop without warning. This can occur during or after feeding, crying or pooping. These tet spells may last a few minutes to a few hours.

Other TOF symptoms may include

• Heart murmur: A swooshing noise heard with a stethoscope
• Tiredness during place or exercise
• Rapid or heavy breathing, especially during feeding 
• Slow growth and weight gain
• Dizziness, fainting or seizures
• Irregular heartbeat (arrhythmia)
• Abnormal shape of the fingertips (clubbing) in older children

Some children with severe forms of TOF may also develop pulmonary atresia. This condition occurs when the heart valve that controls blood flow doesn’t form at all. This means that no blood can pass through to the lungs. 

Diagnosing tetralogy of Fallot

TOF may be diagnosed during pregnancy or after your baby is born.

Tests before birth

During prenatal tests, your health care provider may see something that looks like TOF on an ultrasound. The diagnosis can be confirmed with a fetal echocardiogram (ultrasound) of the baby’s heart to see if the structure is normal.   

Tests after birth

Your child’s health care provider may hear a heart murmur while listening to your child’s heart with a stethoscope. The murmur is from the abnormal flow of blood through the heart. They may also check your baby’s oxygen levels with pulse oximetry.

Your child may need to see a pediatric cardiologist for a diagnosis. This specialist will listen to your child’s heart and lungs and may order one more of these tests:

• Chest X-ray: This test looks at the shape and condition of the heart, lungs and surrounding organs.
• Electrocardiogram (ECG or EKG): This test records the heart’s electrical activity.
• Echocardiogram (echo or ultrasound): This test uses sound waves to create a moving picture of the heart and heart valves.
• Cardiac MRI or CT scan: These tests provide detailed images of the heart.
• Cardiac catheterization: This test uses a thin, flexible tube (catheter) to look at the heart from the inside. 

Diagnosing CHDs like TOF early is very important for your child’s health. Learn more about how heart defects are diagnosed.

Treatment options for tetralogy of Fallot

All babies born with TOF will need surgery to fix the heart and improve blood flow. A cardiovascular (heart) surgeon does the surgery. 

Some babies and children are given medicine while waiting for surgery to help reduce symptoms and help the heart work better. The timing and type of surgery depends on your child’s overall health, age and specific heart problems. 

Two surgical options are:

Complete repair 

Babies born with TOF need open-heart surgery to fix the heart completely. Open-heart surgery involves making a cut (incision) through the chest wall to access the heart. This surgery is usually done within the first year of life. 

A complete repair of TOF is done in several steps. The surgeon closes or patches the hole and repairs or replaces the pulmonary valve. They may also widen the pulmonary valve and reposition the aorta. This helps improve blood flow and oxygen levels.

Recovery may take a few weeks and usually includes a hospital stay, follow-up appointments and imaging tests.

Temporary (palliative) surgery

Some babies need temporary surgery before the complete repair. This surgery increases blood flow to the lungs until the baby is strong enough for a complete repair.

A surgeon may use one of two procedures: 

• Place a tube (surgical shunt) between the large artery that comes off from the aorta and the lung artery.   
• Place a stent (small mesh tube) in the patent ductus arteriosus (a fetal opening between the aorta and the lung artery) or the right ventricular outflow tract (the part of the heart that carries blood from the right ventricle to the lungs). 

In either case, the tube creates a new path for blood to flow to the lungs. The shunt or stent is later removed during open-heart surgery.

Your child’s provider will work with you to determine the best approach for your child. Learn more about treatment options for CHDs.

What happens if tetralogy of Fallot isn’t treated?

Without treatment, TOF can lead to severe health problems, including heart failure, arrhythmias, disability and death. A child with untreated TOF is also at greater risk for endocarditis, an infection of the inner lining of the heart or heart valves. 

Living with tetralogy of Fallot

With proper care and treatment, most children with TOF lead active, healthy lives. Regular follow-up with a cardiologist is important to monitor heart health. Your child may need additional surgeries or treatments as they grow.

Why choose Banner Health

Our Banner Health heart specialists are leading the way in diagnosing and treating a wide range of congenital heart defects, from the most common to the very rare. We treat every patient individually to determine the best treatment.

Schedule an appointment today with one of our specialists.