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Tetralogy of Fallot

What is Tetralogy of Fallot?

Tetralogy of Fallot (TOF) is a congenital heart defect that is a combination of four heart differences.

  • Ventricle septal defect (VSD) – There is a hole between the ventricles (two chambers on the bottom of the heart).

  • Overriding aorta - The blood vessel (aorta) that carries oxygenated (red) blood out of the heart is aligned over the VSD instead of the left ventricle.

  • Pulmonary stenosis - The blood vessel that carries the deoxygenated (blue) blood out of the heart is smaller.

  • Right ventricular hypertrophy – Due to the narrowing of the pulmonary artery, the heart muscle of the bottom chamber on the right side of the heart is thicker than normal.

Tetralogy of Fallot causes

Tetralogy of Fallot occurs in about 1 in every 2,500 births. The cause is unknown, though it is more common in babies who also have Down syndrome or DiGeorge syndrome.

How to diagnose Tetralogy of Fallot

Tetralogy of Fallot may be diagnosed before your baby is born. Your doctor may notice a concern during your 20-week ultrasound and order a follow-up test called a fetal echocardiogram. The Fetal Health Center at Children’s Mercy can assist in diagnosing TOF and caring for you and your baby during delivery and after birth.

Often, TOF is diagnosed shortly after birth, before your newborn leaves the hospital, or at an early checkup in the first few weeks of life.

Signs and symptoms of Tetralogy of Fallot

Your doctor may notice the following signs of TOF in your baby:

  • Heart murmur

  • Blue tint to the skin (cyanosis)

  • Newborn pulse oximetry screening

Testing for TOF

These tests can help your care team diagnose TOF and create a treatment plan for your baby:

Basic Testing:

  • Pulse oximetry: a way to monitor the oxygen content of the blood via a light probe placed on your baby’s hand or foot. This test is not painful.

  • Electrocardiogram (ECG): a visual representation of the heart's electrical activity captured via monitors placed on the skin. This test is not painful.

  • Echocardiogram (echo): an ultrasound of the heart that evaluates the structure and the function of the heart by using sound waves. Still and moving pictures of the heart structures, heart valves, and heart function are recorded for review by a cardiologist. This test is not painful.

  • Chest X-ray: a test that uses a small amount of radiation to create an image (or picture) within the chest to include the heart, lungs, blood vessels and bones. This test is not painful.

Advanced Testing—These studies may require sedation for completion:

  • Cardiac MRI: a test that produces images (or pictures) of the body with the use of x-rays. The MRI uses a large magnet, radio waves, and a computer program to produce three-dimensional image of your chest that can show heart abnormalities. This test is not painful.

  • Cardiac catheterization: a procedure where a catheter (small tube) is inserted into your baby’s heart through a large vein or artery in the leg to take pictures and pressure measurements. There may be some soreness at the insertion site following this procedure.

Tetralogy of Fallot Treatment

Treatment for Tetralogy of Fallot can vary from one child to another, but all will require surgical repair. The timing of the operation varies but is usually within the first few months of life. The surgery consists of a patch to cover the hole (VSD) and widening of the pulmonary valve or artery.

If the pulmonary stenosis is very severe, your baby may require a temporary repair such as a shunt or stent to get blood to the lungs. Then, the surgery for the complete repair takes place at a later time.

Children’s Mercy has many skilled cardiology providers to care for your baby. If your baby requires an intervention, such as a shunt or stent, before the full repair, they might participate in our Cardiac High Acuity Monitoring Program (CHAMP®)

What to expect when your baby has TOF

If your baby is diagnosed before birth with TOF, you may choose to deliver in the Fetal Health Center, where our specialists can provide any care your baby needs immediately after delivery, all while you stay close by.

Some families choose to deliver with their primary obstetrician and then come to Children’s Mercy for consultations and surgery after birth. You and your care team can decide which option is best for you.

Babies who are born with TOF are usually transferred to the neonatal intensive care unit (NICU) for monitoring. Children’s Mercy has the only Level IV (highest level) NICU in the region. Depending on your baby's individual condition, they may be able to go home before surgery or they may stay in the hospital for some type of surgical treatment before going home.

If your baby needs heart surgery, they will go to our cardiac intensive care unit following surgery. After your baby heals from surgery, they will continue to receive care on our cardiology floor.

Healthy Heart

Sometimes, it’s easier to understand how your child’s heart is different if you have a clearer picture of how a healthy heart works. Experts at the Heart Center have provided the basics to help you learn about the heart’s structure and function.

Choosing the best home for your child’s care


USNWR Cardiology

The Heart Center at Children’s Mercy provides comprehensive care for your child as they grow. In addition to top-ranked medical care, we will support your entire family through our Thrive program, which gives you resources and care throughout your journey.

When you’re choosing a care team for your child, it can be helpful to see how often our doctors perform certain procedures and how well children do after the surgery is over. Our surgical team performs hundreds of pediatric heart surgeries each year, often with outcomes that are better than the national average.

The information on our Cardiovascular Surgery Outcomes page help you see the number of cases we complete each year, organized by procedure, along with a numerical score that represents our outcomes—how the children did after surgery.  The Society of Thoracic Surgeons (STS) score is calculated from a database of surgical outcomes from congenital heart surgery centers across North America. By comparing our numbers to the STS score, you can see how we perform compared to other surgical centers who complete the same types of surgeries.

Learn more about our Heart Center

Care for your growing child

Following your baby’s surgery, they will need close follow-up care with a cardiology provider. These visits will be spaced out as your baby grows. Even though most children lead healthy, active lives, your child will need cardiology care for their whole life.

Your child’s cardiology provider will continue to monitor via echocardiogram (heart ultrasound) and electrocardiogram (heart electrical activity) for heart valve problems or for problems with the heart’s electrical system (arrhythmia, abnormal heart beat). Since most babies born with Tetralogy of Fallot will live full lives into adulthood, as they reach an appropriate age, we will help your child transition to an adult congenital heart specialist.