Tetralogy of Fallot (ToF, Tet)

  • Surgery for tetralogy of Fallot even 30 years ago was very good, but we continue to improve our medical and surgical management of this condition. Recent advances at Children's and elsewhere have made the surgery safer and more effective, and promise to improve upon already excellent long-term results

    ––Thomas Kulik, MD, cardiac intensivist, Boston Children's Hospital

    If your infant or child has been diagnosed with tetralogy of Fallot (ToF), an understanding of the condition will help you to cope with this combination of congenital (present at birth) heart defects. While serious, ToF is treatable surgically, and the long-term outlook for the vast majority of children is excellent.

    Tetraology of Fallot

    ToF is a combination of four cardiac anatomic characteristics:
    • ventricular septal defect (VSD): This is a hole between the right and left pumping chambers (ventricles) of the heart.
    • right ventricular outflow tract obstruction: The connection between the heart and the artery that goes to the lungs (pulmonary artery) is narrowed and blood flow to the lungs is reduced.
    • overriding aorta: The major blood vessel from the heart to the body connects to the heart a bit further to the right than normally.
    • hypertrophy of the right ventricle: The right-sided pumping chamber (ventricle) is thicker than normal because it’s pumping blood at a higher-than-normal pressure.
    • Some babies have a severe degree of obstruction to blood flow to the lung, while others have less narrowing and therefore only mild obstruction. The degree of obstruction generally becomes worse with time.
    • Babies usually show the symptom of cyanosis (bluish tinge to skin). This can become apparent shortly after birth, or weeks to months later.
    • Repair is surgical, usually in the first 3 to 6 months of life. Some babies may be candidates for treatment by cardiac catheterization as a temporizing measure, but all will eventually need open heart surgery.
    • ToF is always present at birth (congenital).
    • ToF affects about 2 in 10,000 children and is the most common cyanotic heart defect.
    • ToF occurs equally in boys and girls.
    • ToF can be associated with cleft lip and palate and other craniofacial abnormalities; children with Down syndrome have a higher incidence of ToF.

    How Boston Children' Hospital approaches tetralogy of Fallot

    Our team in Boston Children’s Heart Center understands how distressing a diagnosis of tetralogy of Fallot can be for parents. You can have peace of mind knowing that our surgeons treat some of the most complex pediatric heart conditions in the world, with excellent results.

    Our outcomes for repair of ToF, measured over the last two years, is greater than 92 percent survival for neonates in the first 30 days of life, and greater than 99 percent survival for patients beyond 30 days of age.

    We have found that the following elements provide the best possible outcomes for patients with ToF:

    • accurate diagnosis and assessment: We utilize the most advanced techniques available for determining the baby’s cardiac anatomy, with interpretation by highly experienced cardiologists.
    • close, expert medical follow-up before and after surgical repair. If you live in the Boston area, a Boston Children’s cardiologist will follow your child; if you live in another part of the country, a Boston Children’s cardiologist will work closely with your local cardiologist. Adult patients with tetralogy are followed in our BACH program by Boston Children’s cardiologists who have special training for adults with congenital heart problems.
    • the availability of a variety of therapies, depending upon the exact needs of each child. Boston Children’s surgeons have extensive experience performing the complex procedures required by this condition. Boston Children’s brings together cutting-edge imaging techniques and highly experienced pediatric heart specialists to create therapies for even the most complex forms of this defect.
    • a highly experienced, skilled team to bring together the many pieces of the therapeutic puzzle: Boston Children’s cardiac surgeons work with highly experienced nurses and doctors who are focused on providing expert care before and after surgery. Boston Children’s Cardiac Intensive Care Unit (CICU) is one of the first such units to be developed anywhere, and professionals from many countries visit the CICU to learn advanced techniques of postoperative care.

    Our specialized training in pediatric cardiology and cardiac surgery means that we understand the unique challenges, circumstances and intricacies of working with young people who have heart conditions. In addition to our medical expertise, we provide patient-centered care that always recognizes your child as an individual—and we offer resources to meet the needs of your entire family.

    Tetralogy of Fallot: Reviewed by Thomas Kulik, MD
    © Boston Children's Hospital, 2011

    Boston Children’s history of heart care innovation

    In 1938, Boston Children’s cardiac surgeon Robert Gross, MD, performed the world’s first successful surgery to correct a child’s heart defect. Since that time, we have gained recognition around the globe for our leadership in pediatric cardiology, and continue to make critical advances in the field.

  • Tetralogy of Fallot

    What is Tetralogy of Fallot (ToF)?

    In a normal heart, oxygen-poor (blue) blood returns to the right atrium from the body and travels to the right ventricle. Then, it is pumped through the pulmonary artery into the lungs, where it receives oxygen. Oxygen-rich (red) blood returns to the left atrium from the lungs, passes into the left ventricle and then is pumped through the aorta out to the body.

    But in ToF, the abnormal features prevent enough oxygen-poor (blue) blood from flowing to the lungs as it should. As a result, a person with ToF has a lower-than-normal amount of oxygen in the blood. Surgical intervention is needed.

    In ToF, there are four cardiac anatomic characteristics:

    • Right ventricular outflow tract obstruction: The connection between the heart and the artery that goes to the lungs (pulmonary artery) is narrowed and blood flow to the lungs is reduced.
    • Overriding aorta: The major blood vessel from the heart to the body connects to the heart a bit further to the right than it normally does.
    • Hypertrophy of the right ventricle: The right-sided pumping chamber (ventricle) is thicker than normal because it’s pumping blood at a higher-than-normal pressure.

    What is tetralogy of Fallot with pulmonary atresia (ToF/PA)?

    ToF/PA is a more severe variant of ToF.

    • Babies with ToF/PA often show cyanosis (bluish tinge to skin) after birth, but in some cases this condition becomes apparent only at an older age. 
    • Surgery to repair or partially correct the defects is usually done within in the first six months of a baby’s life. Often, more than one operation is needed.

    ToF/PA is a combination of cardiac anatomic characteristics:

    • Overriding aorta: moves toward right side of heart; located just over the ventricular septal defect
    • Hypertrophy of the right ventricle: becomes abnormally enlarged because it’s attempting to compensate for the pulmonary obstruction
    • No connection between the right ventricle and the pulmonary arteries: blood flow into the lungs is through blood vessels running from the aorta to the pulmonary arteries
    • Abnormal pulmonary arteries: The number, size and arrangement of pulmonary arteries are extremely variable in this disease. This often constitutes the biggest challenge for therapy since it may be necessary to connect multiple pulmonary arteries together and then to the right ventricle.

    What are the symptoms of ToF?

    • Cyanosis is sometimes the first sign to be recognized. Cyanosis is marked by a blue color of the skin and mucus membranes due to a lower-than-normal amount of oxygen in the blood.
    • In many cases, a heart murmur—perhaps detected at a well-child visit—is the first sign of ToF. (Note: The overwhelming majority of murmurs in babies and older children are not associated with any cardiac abnormality.)
    • Congenital heart defects like ToF usually occur by chance, with no clear reason for their development. So, it’s difficult to predict who’s at risk. But in ToF, familial cases have been reported, and a genetic link has been confirmed in some cases.
    • Parents who have a child with a ToF (or another congenital heart defect) have a somewhat greater chance of having a second child with a heart defect.
    • Even after it’s apparent that a baby has ToF, there may be few symptoms for weeks or even months. A few babies will have signs of cardiac overwork—becoming tired with feeding, poor weight gain—if the amount of pulmonary obstruction is mild.
    • More commonly, the baby has few symptoms at first. But, over time, the cyanosis increases. Eventually, the cyanosis becomes so severe that it interferes with normal growth, development and activities.
    • “Tet spells,” also known as “hypercyanotic episodes,” are also a concern. During these episodes—which often occur after feeding, warm baths or stress—the baby has a sudden decrease in the amount of oxygen in his blood. He becomes deep blue, breathes faster than normal and may appear to be very irritable or crying. During these episodes, the oxygen level may become so low that the baby’s life is threatened. Babies having a tet spell need urgent medical attention.

    How is ToF diagnosed?


    A diagnosis of ToF is usually made by echocardiogram (cardiac ultrasound). Other tests may be used to provide additional information.

    How is ToF treated?

    • Surgery. Babies with ToF must have open heart surgery for repair. Surgery is usually performed in the first 3 to 6 months of life, although it can be performed earlier, if needed. This surgery consists of closing the VSD (usually using Dacron cloth) and relieving the narrowing between the right ventricle and pulmonary artery. 
    • Catheterization. Some babies may require catheterization to obtain information not available from echocardiography. Occasionally, a baby may benefit from interventional catheterization to widen the connection between the right ventricle and the pulmonary artery. This procedure can serve as a temporary way to increase the oxygen level in the blood.

    What are the long-term effects of ToF?

    Your child may need additional operation(s) or catheterization(s) as he grows older. Although the goal of the operation is to repair the defect, some patients will develop leakage from the pulmonary valve that requires replacement. This usually occurs in adolescence or later adulthood, although it can occur sooner.

    Teenagers with congenital heart defects will have to deal with medical appointments and procedures and possible restrictions on physical activities.

    Adults who were treated for congenital heart disease as a child will need to be followed by a cardiologist because complications from early heart disease can arise in adulthood. ToF patients may be at some risk for arrhythmias, leaky valves and other heart problems.
    Non-cardiac surgeries may pose risks for some patients and will require evaluation and discussion with a cardiologist. For female patients, pregnancy may also present risks.

    Boston Children's helps adults with congenital heart defects, too.

    Boston Children’s Heart Center is the largest pediatric heart program in the United States. Our staff of more than 80 pediatric cardiac specialists cares for thousands of children and adults with congenital and acquired heart defects each year, from simple to complex cases. We have experience treating rare heart problems—with results that are among the best in the world.

  • At Boston Children's Hospital, we know that the first step in treating your child is forming an accurate, complete and timely diagnosis.

    The exam

    This pediatric cardiologist will listen to your baby’s heart and lungs, feel the baby’s pulses, measure the oxygen level in the blood (non-invasively) and make other observations that help to determine the diagnosis.

    The tests

    Your child’s doctor will also use some combination (not necessarily all) of the following medical tests to diagnose ToF:

    • echocardiogram (cardiac ultrasound): An echocardiogram evaluates the structure and function of your child’s heart using electronically recorded sound waves that produce a moving picture of the heart and heart valves. No discomfort is involved. It takes 30-60 minutes. Many younger (less than 3 yrs old) children may need to be sedated. An ultrasound can also detect ToF prenatally.
    • electrocardiogram (EKG): An EKG is used to evaluate the electrical activity of your child’s heart. An EKG is often the initial test for evaluating the causes of symptoms and detecting heart abnormalities. It is performed by placing electrodes on the arms, legs and chest to record the electrical activity. The test takes five minutes or less and involves no pain or discomfort.
    • cardiac magnetic resonance imaging (MRI): A cardiac MRI is a non-invasive test using 3-D imaging technology to accurately determine the shape, size, and function of your child’s heart. No pain is involved, although an IV may be needed. It takes about an hour. Children under 10 years usually need anesthesia.
    • chest x-ray: A conventional chest x-ray will evaluate the size and spatial relationships of the heart within the child’s chest. It takes a few moments. There’s no pain or discomfort.
    • cardiac catheterization: This invasive procedure (a procedure that penetrates the body) performed under sedation or anesthesia provides detailed information and measurements about the structures inside the heart. Blood pressure and oxygen measurements are taken in the four chambers of the heart, as well as the pulmonary artery and aorta. Moving pictures are taken of the heart and blood vessels using x-ray dye to further observe their structure.
    • pulse oximetry: a non-invasive test (a test that doesn’t require penetrating the body) to measure the amount of oxygen in the blood
  • Initial approaches

    Some newborns with a severe form of ToF and markedly reduced oxygen in the blood will need to be admitted to the cardiac intensive care unit (CICU). In these cases, the baby will usually be placed on oxygen, and sometimes on a ventilator (a machine which breathes for the baby). 

    Intravenous (IV) medication may be given to help your baby’s heart and lungs function more efficiently. An IV medication called prostaglandin E1 is sometimes given to keep the baby’s ductus arteriosus from closing. (The ductus arteriosus is the prenatal connection between the aorta and the pulmonary artery, which usually closes shortly after birth, but which is now important as a temporary alternative opening for blood flow.)

    Cardiac catheterization

    Most babies with ToF do not need catheterization, but this procedure is occasionally needed for diagnostic reasons. A few babies may benefit from a procedure performed in the catheterization laboratory to enlarge the connection between the right ventricle and the pulmonary artery, as a temporary way to increase oxygen in the blood.


    Babies with ToF are usually treated with surgery between about 3 and 6 months of age. If needed, they can have the operation sooner. For most babies, corrective surgery (as described below) is performed as the initial operation. A few babies may require palliative surgery before correction, usually in the form of a modified Blalock-Taussig “shunt” (a small Gore-Tex tube surgically placed between the aorta and the pulmonary artery) to increase the quantity of blood going to the lungs.

    Surgical correction of ToF consists of the following:

    • Relieving the narrowing between the right ventricle and pulmonary artery: This entails removing excess muscle tissue, and sometimes placing a small patch of pericardium or other material between the right ventricle and pulmonary artery to further open this area up.  Sometimes it is necessary to place a tube (conduit) between the right ventricle and the pulmonary artery to provide a pathway for blood flow.

    The operation is performed while the patient is on the pump-oxygenator (heart-lung machine), which takes over for the heart and lungs while the surgeon is working on the heart.

    Surgical correction of ToF/PA consists of the following:

    • connecting all, or as many as possible, of the pulmonary arteries together, so that they can be connected to the right ventricle, usually by attaching a tube (conduit) from the pulmonary arteries to the right ventricle
    • in many cases, more than one operation will be required to bring the pulmonary arteries together. In some cases, the VSD may not be closed, or may only be partially closed. 

    Post-operative care. After the operation, the baby is taken to the cardiac intensive care unit (CICU), where his vital signs and other factors are very closely monitored. In most cases, the baby’s CICU stay will be one or two days (often longer for ToF/PA), followed by a few days of recovery on “8E,” the unit where patients with cardiac conditions are followed. After your child’s hospital discharge, his cardiologist and pediatrician will provide follow-up monitoring and care.

    Coping and support

    On our For Patients and Families site, you can read all you need to know about:

    • getting to Boston Children’s
    • finding accommodations
    • navigating the hospital experience
    • taking advantage of resources that are available for your family
  • In 1938, Boston Children’s Hospital’s cardiac surgeon Robert Gross, MD, performed the world’s first successful surgery to correct a child’s heart defect. Since then, we’ve been recognized around the globe for our leadership in pediatric cardiology, and we continue to make critical advances in the field.

    Examples of our innovative approach to ToF, are given below.

    Repairing pulmonary valves in ToF patients:

    Children with ToF often have small pulmonary valves, which do not open properly, in need of repair. The standard treatment is to enlarge the valve by placing a patch across it, which can often leave a child with a leaky valve. To tackle this problem, doctors at Boston Children’s began a program aimed at trying to preserve the function of the pulmonary valve by using a balloon to enlarge and open it in the operating room. It is hoped that this technique will reduce the tendency for leakage from the pulmonary artery into the right ventricle, which can cause overwork and weakness of the ventricle over time.

    A new prosthetic valve to treat congenital heart disease patients:

    Boston Children’s was one of a small number of centers to test and first use the Medtronic Melody Transcatheter Pulmonary Valve, a prosthetic valve developed to treat patients with congenital heart disease affecting the function of the pulmonary valve. This valve is very useful for some older patients who’ve developed significant pulmonary leakage (regurgitation) after repair of ToF. The valve is implanted through a catheter procedure, rather than a more invasive open-heart surgical procedure. This makes the child's recovery much easier and far less intensive.

    Like other prosthetic valves, the Melody valve is likely to need replacement several times over the course of a patient's life due to wear and tear. However, since the Melody can be implanted through a catheter, there is minimal risk to the patient compared to valves that can only be implanted surgically.

    Learn more about Boston Children’s cardiac surgery research initiatives and current projects in cardiology research.

  • From Iceland to Boston

    I'm from Iceland.  I am the mother of a boy, Ásgeir Valur, who  was born with a heart defect called Tetralogy of Fallot. During the pregnancy we also found out he only had one kidney. But luckily, the kidney has never Asgeir Valurbeen a problem. It works fine, as it should.  We found about the heart defect when I was 7 months into the pregnancy and it was quite a coincidence that it was discovered then, because it was not seen in 20 weeks sonar, nor 25th week sonar (which I had because of the doctor wanted to be sure there was only one kidney there). But I‘m glad it was discovered during the pregnancy because then we had two months to prepare for what was coming. Most parents get the news after their baby is born.

    He was taken with c-section (after his heart rate dropped during birth) the 11th of February and he was taken immediately to the newborn ICU. But I knew that would happen.  His father went with him but I saw him 2 hours later.  He was christened  the day after his birth. When he was two days old he got  a Blaloc-Taussig shunt in Landspitalinn (The hospital of Reykjavik, Iceland) and he spent his first three weeks there. The shunt was successful and we could take him home.  For the next 7 months he got home-nurse vising us three times a week and in July-August (2004) we had a very difficult 6 weeks as he refused to drink anything. He did not want his milk and the feeding was really a struggle.  But we survived.  I‘m lucky he was my first child as I did not have any comparison of how it was to have a healthy child.

    In September his cardiologist decided it was time to prepare for the big operation and we had one month to make the passport and everything else ready.  The 29th of September me, my husband and son met the doctor on the airport and took of to Boston. We were lucky as my mother and my mother-in-law had decided to buy their own tickets to Boston to be with us for support. It was good to have their support when we was abroad.  We did not have to have any financial concerns as the government paid the flight for me, my husband and son, the stay at the hotel and the hospital bill. I don‘t think a can complain about high taxes again!

    Ásgeir ValurThe flight took about 6 hours, and my sons sO2 dropped to 62% during the flight. I was a bit worried but then I decided to look more on my child than the machine, because he was happy playing with the oxygen mask!  The trip from the airport to the hospital was the fastest one through airport I have ever had.  We had our passport checked inside the airplane, then a few guards took us the shortest way through the airport straight into an ambulance. We were at the hospital with our son in his hospital bed 45 minutes after the plane landed.  That was fast! We did not have to wait for our luggage  because we had been told, only to take handbags with us.  I thought it was crazy to go to another country for 2 ½ weeks with only clothes in our handbags, and a lot of the luggage was our son‘s! Toys, clothes, bottles, diapers (for the flight) and all the stuff that baby needs! The most problem was finding the right milk formula he would drink because the one he was used to drink did not exist in Boston. The painkillers were also different. He had Tylenol at the hospital for painkillers, but we were used to give him Parasupp. There was lot of other little things, like that. Nurses in Iceland tell us not to microwave the milk for babies, but it was the only option to heat the milk at the hospital. But those little things did not bother us too much, we just learnt new ways, and the staff at the hospital was very nice and helpful. We felt like our son was in the best hands.

    We stayed at the hotel across the street so it only took us 2 minutes to get to the hospital. We switch places in spending the night at the hospital with our son. And the whole time he was sleeping by the Icelandic clock, which meant that he thought it was morning at 4:30 a.m.

    Ásgeir ValurThe day after we arrived to Boston (the 30th of September) he had catheterization (it‘s very hard for me to remember this word!), which was performed by Dr. Armsby and it was very successful. This was on Thursday and we were lucky that he was allowed to spend the weekend at the hotel. He had a little bit fever, but nothing serious. His father took the most amazing photo of him at the hotel with the hospital band around his leg.  We call this photo "Go Red Socks" because he looks like a supporter of a team and while we were in Boston Red Socks won the World Series Championship.

    The Tuesday the 5th of October he had the big operation, which was performed by Del Nido.  The operation got delayed by few hours, but we kept in contact with our family and friends through his blog, which we tried to update currently.  However, everybody in Iceland had forgotten to tell his great grandmother that the operation got delayed and she was really really nervous for his behalf.  She though something must have gotten wrong, but that was not the case.  The operation was very successful, even more successful than anybody thought.  His cardiologist had expected that he would have had several surgeries while growing, and few catheterizations but in fact he has only had one catheterization since then and no other surgery. The original plan was to put some Gore-Tex patch inside to widen his pulmonary artery, but luckily the surgeon could use living tissue from my son‘s heart instead! 

    The first time I saw him after the operation, I really did npt notice all the tubes and stuff, what I saw, was his beautiful pink skin.  He had never been so pink before.  Most other people would probably have noticed the  tubes, but I did not. He was in the heart ICU until Friday, then he was moved into 6 East (which I believe, has moved to the 8th floor by now...  ).  We had still another culture shock on the ICU. In Iceland, you are not allowed to go into the ICU if you are wearing fleece sweater, and no shoes or other outdoor clothes.  Children (up to 16 years old) where not allowed to visit the newborn ICU in Iceland. My husband brother who was 15 years old when our son was born, was not allowed to see him until he got home from the new born ICU.  Here, we could would in the ICU in our fleece sweaters, in our outdoor shoes and everything!   We were so surprised by that. But after we got over the culture shock we found out that the staff at the ICU was really nice and they did really care. We felt like our son was in the best hands.

    On 6 East we got a one person room, with our son‘s hospital bed, lazyboy and TV. That was luxury. I don‘t recall of having a one person room in a hospital before.  Usually, you have to share the room with 2-5 persons! But it was good to have this private room, I think we got it because our son was waking up in the middle of the night thinking it was morning (he was the whole time by the Icelandic clock). The first night we had been in a two person‘s room and our son and the other baby kept each other awake.

    In 6 East, we kept getting this good service by the people, and when we noticed that he did not want to sleep in his bed, we spoke to the nurses, and they agreed with us to leave him always alone in the bed, if they needed to take his blood, or do something (he did not like), he was always taken into another room, which made the bed his safe place.  I really liked that.  He was also terrified of the X-rays so when he had had X-rays or several blood works done, we used to buy him an ice cream. It worked surprisingly well, because the ice cream seemed to make him forget the pain. (Luckily, they had ice cream in the cafeteria!). He is not afraid of doctors after this stay, in fact, he likes doctors very much.

    We stayed on the Children‘s hospital until the 15th of October (which was Friday). We left the hospital in the afternoon and got to the airport. I think the flight was in the evening, but due to time difference, we landed in Iceland early Saturday morning.  The grandmothers had left two days earlier (which was our original departure date, but the departure was delayed by two days, because our son had a little fluid around his heart, but when we left we got Lasix with our which he had to take for a week or so), so when we came home, they were waiting at our home with breakfast ready for us. That was nice.

    Ásgeir ValurIt is difficult to have ones child in a hospital and even more difficult to have the child in a hospital in another country, but the doctors, the nurses and all the other staff, made our stay as pleasant as possible.  I really want to return to Boston someday, and then go there as a tourist, and I hope I can take my son to visit Children‘s hospital, so I can show him the place, he had his life changing surgery. 

    He is now 6 years old, he is very happy boy having a totally different life, than expected.  He practices swimming three times a week, he takes dancing lessons and plays piano.  Just the things you expect a normal child to do. His scar is almost invisible, so he does not have to worry about people staring at him when he goes swimming.

    --- S. Andrea Ásgeirsdóttir

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