Tetralogy of Fallot (teh-TRAL-uh-jee of fuh-LOW) is a rare condition caused by a combination of four heart defects that are present at birth.

These defects, which affect the structure of the heart, cause oxygen-poor blood to flow out of the heart and to the rest of the body. Infants and children with tetralogy of Fallot usually have blue-tinged skin because their blood doesn't carry enough oxygen.

Tetralogy of Fallot is often diagnosed during infancy or soon after. However, tetralogy of Fallot might not be detected until later in life, depending on the severity of the defects and symptoms.

With early diagnosis followed by appropriate surgical treatment, most children who have tetralogy of Fallot live relatively normal lives, though they'll need regular medical care and might have restrictions on exercise.

Tetralogy of Fallot symptoms vary, depending on the extent of obstruction of blood flow out of the right ventricle and into the lungs. Signs and symptoms may include:

  • A bluish coloration of the skin caused by blood low in oxygen (cyanosis)
  • Shortness of breath and rapid breathing, especially during feeding or exercise
  • Loss of consciousness (fainting)
  • Clubbing of fingers and toes — an abnormal, rounded shape of the nail bed
  • Poor weight gain
  • Tiring easily during play or exercise
  • Irritability
  • Prolonged crying
  • A heart murmur

Tet spells

Sometimes, babies who have tetralogy of Fallot will suddenly develop deep blue skin, nails and lips after crying or feeding, or when agitated.

These episodes are called tet spells and are caused by a rapid drop in the amount of oxygen in the blood. Tet spells are most common in young infants, around 2 to 4 months old. Toddlers or older children might instinctively squat when they're short of breath. Squatting increases blood flow to the lungs.

When to see a doctor

Seek medical help if you notice that your baby has the following symptoms:

  • Difficulty breathing
  • Bluish discoloration of the skin
  • Passing out or seizures
  • Weakness
  • Unusual irritability

If your baby becomes blue (cyanotic), place your baby on his or her side and pull your baby's knees up to his or her chest. This helps increase blood flow to the lungs. Call 911 or your local emergency number immediately.

Tetralogy of Fallot occurs during fetal growth, when the baby's heart is developing. While factors such as poor maternal nutrition, viral illness or genetic disorders might increase the risk of this condition, in most cases the cause of tetralogy of Fallot is unknown.

The four abnormalities that make up the tetralogy of Fallot include:

  • Pulmonary valve stenosis. Pulmonary valve stenosis is a narrowing of the pulmonary valve — the valve that separates the lower right chamber of the heart (right ventricle) from the main blood vessel leading to the lungs (pulmonary artery).

    Narrowing (constriction) of the pulmonary valve reduces blood flow to the lungs. The narrowing might also affect the muscle beneath the pulmonary valve.

  • Ventricular septal defect. A ventricular septal defect is a hole in the wall that separates the two lower chambers of the heart — the left and right ventricle. The hole allows deoxygenated blood in the right ventricle — blood that has circulated through the body and is returning to the lungs to replenish its oxygen supply — to flow into the left ventricle and mix with oxygenated blood fresh from the lungs.

    Blood from the left ventricle also flows back to the right ventricle in an inefficient manner. This ability for blood to flow through the ventricular septal defect reduces the supply of oxygenated blood to the body and eventually can weaken the heart.

  • Overriding aorta. Normally the aorta — the main artery leading out to the body — branches off the left ventricle. In tetralogy of Fallot, the aorta is shifted slightly to the right and lies directly above the ventricular septal defect.

    In this position the aorta receives blood from both the right and left ventricles, mixing the oxygen-poor blood from the right ventricle with the oxygen-rich blood from the left ventricle.

  • Right ventricular hypertrophy. When the heart's pumping action is overworked, it causes the muscular wall of the right ventricle to thicken. Over time this might cause the heart to stiffen, become weak and eventually fail.

Some babies who have tetralogy of Fallot may have other heart defects, such as a hole between their heart's upper chambers (atrial septal defect).

While the exact cause of tetralogy of Fallot is unknown, various factors might increase the risk of a baby being born with this condition. These risk factors include:

  • A viral illness during pregnancy, such as rubella (German measles)
  • Alcoholism during pregnancy
  • Poor nutrition during pregnancy
  • A mother older than age 40
  • A parent who has tetralogy of Fallot
  • The presence of Down syndrome or DiGeorge syndrome

All babies who have tetralogy of Fallot need corrective surgery. Without treatment, your baby might not grow and develop properly.

Your baby may also be at an increased risk of serious complications, such as infective endocarditis — an infection of the inner lining of the heart or heart valve caused by a bacterial infection.

Untreated cases of tetralogy of Fallot usually develop severe complications over time, which might result in death or disability by early adulthood.

You're likely to start by seeing your family doctor or a general practitioner. However, you'll then be referred to a doctor trained in treating heart conditions (cardiologist). Your child will often be referred to a doctor trained in treating children with heart conditions (pediatric cardiologist).

Here's some information to help you get ready for your appointment, and what to expect from your child's doctor.

What you can do

  • Be aware of any pre-appointment restrictions. When you make the appointment, ask if there's anything you need to do in advance, such as restrict your child's diet.
  • Write down any symptoms your baby is experiencing, including any that might seem unrelated to the reason for which you scheduled the appointment.
  • Write down your child's family history, including details from both the maternal and paternal sides of the family.
  • Ask a family member or friend to come with you, if possible. Sometimes it can be difficult to remember all of the information provided to you during an appointment. Additionally, learning that your baby has a heart defect is upsetting news, which might make it harder for you to remember what the doctor says afterward. Someone who accompanies you might help you remember the doctor's recommendations.
  • Write down questions to ask your child's doctor.

Preparing a list of questions can help you make the most of your appointment time. For tetralogy of Fallot, some basic questions to ask your child's doctor include:

  • What's the most likely cause of my child's symptoms?
  • Are there other possible causes of these symptoms?
  • What kinds of tests does my child need? Do these tests require special preparation?
  • What treatments are available, and which do you recommend?
  • What are the possible complications of surgery?
  • What's my child's prognosis after surgery? Can he or she live a normal life?
  • My child has other health conditions. How can I best manage them together?
  • Are there any activity restrictions that my child will need to follow?
  • Will he or she be able to play sports? Participate in gym?
  • Why did this happen?
  • Will this happen again in future pregnancies, and is there any way to prevent it?
  • Are there any brochures or other printed material that I can take home with me? What websites do you recommend?

In addition to the questions that you've prepared ahead of time, don't hesitate to ask other questions during your appointment.

What to expect from your doctor

Your child's doctor is likely to ask you a number of questions, such as:

  • When did you first notice your child's symptoms?
  • Have your child's symptoms been continuous, or occasional?
  • Does anything seem to improve your child's symptoms?
  • What, if anything, appears to worsen your child's symptoms?
  • How is your child feeding and sleeping?
  • Have you noticed fainting spells or episodes when your child's lips and skin become more blue or dusky?
  • Is your child vomiting or losing weight?

What you can do in the meantime

While you're waiting for the doctor's appointment and for treatments, here are a few tips to help make your baby more comfortable:

  • Feed your baby slowly. Try smaller, more frequent meals.
  • Help your child during a tet spell. Your child's skin, nails and lips might turn blue after crying, feeding or waking up. If you can remain calm, it can help reduce your child's anxiety. Improve circulation to your child's heart and lungs by gently raising his or her knees to the chest.

After your baby is born, your baby's doctor might suspect tetralogy of Fallot if your baby has blue-tinged skin or if a heart murmur — an abnormal whooshing sound caused by turbulent blood flow — is heard in your baby's chest. Your baby's cardiologist will conduct a physical examination and use several tests to confirm the diagnosis.

Tests may include:

  • Echocardiography. Echocardiograms use high-pitched sound waves to produce an image of the heart. Sound waves bounce off your baby's heart and produce moving images that can be viewed on a video screen.

    This test is generally used to diagnose tetralogy of Fallot. It allows your baby's doctor to determine if there is a ventricular septal defect and where it's located, if the structure of the pulmonary valve and pulmonary artery is normal, if the right ventricle is functioning properly, and if the aorta is positioned properly. This test can also help your baby's doctors to plan treatment for your baby's condition.

  • Electrocardiogram. An electrocardiogram records the electrical activity in the heart each time it contracts. During this procedure, patches with wires (electrodes) are placed on your baby's chest, wrists and ankles. The electrodes measure electrical activity, which is recorded on paper.

    This test helps determine if your baby's right ventricle is enlarged (right ventricular hypertrophy), if your baby's right atrium is enlarged and if the heart rhythm is regular.

  • Chest X-ray. A chest X-ray can show the structure of your baby's heart and lungs. A common sign of tetralogy of Fallot on an X-ray is a "boot-shaped" heart, because the right ventricle is enlarged.
  • Oxygen level measurement (pulse oximetry). This test uses a small sensor that can be placed on a finger or toe to measure the amount of oxygen in your baby's blood.
  • Cardiac catheterization. Doctors may use this test to evaluate the structure of the heart and plan surgical treatment. During this procedure, your baby's doctor inserts a thin, flexible tube (catheter) into an artery or vein in your baby's arm, groin or neck and threads it up to his or her heart.

    Your baby's doctor injects a dye through the catheter to make your baby's heart structures visible on X-ray pictures. Cardiac catheterization also measures pressure and oxygen levels in the chambers of the heart and in the blood vessels.

Surgery is the only effective treatment for tetralogy of Fallot. Surgical options include intracardiac repair or a temporary procedure that uses a shunt. However, most babies and older children have intracardiac repair.

Your child's doctors will determine the most appropriate surgery and the timing of the surgery based on your child's condition.

Intracardiac repair

This open-heart surgery is usually done during the first year after birth. The surgeon places a patch over the ventricular septal defect to close the hole between the lower chambers of the heart (ventricles).

He or she also repairs or replaces the narrowed pulmonary valve and widens the pulmonary arteries to increase blood flow to the lungs. After intracardiac repair, the oxygen level in the blood increases and your child's symptoms will lessen.

Temporary surgery

Occasionally babies need to undergo a temporary surgery before having intracardiac repair.

If your baby was born prematurely or has pulmonary arteries that are underdeveloped (hypoplastic), the surgeon will create a bypass (shunt) between a large artery that branches off from the aorta and the pulmonary artery.

This bypass increases blood flow to the lungs. When your child is ready for intracardiac repair, the surgeon removes the shunt during the procedure for intracardiac repair.

After surgery

While most babies do well after intracardiac repair, complications are possible. Complications may include:

  • Chronic pulmonary regurgitation, in which blood leaks through the pulmonary valve back into the pumping chamber (right ventricle)
  • Irregular heartbeats (arrhythmias)
  • Aortic root dilation, in which the ascending aorta enlarges

Sometimes blood flow to the lungs may still be restricted after intracardiac repair. Infants, children or adults with these complications might require additional surgeries. In some cases, the pulmonary valve might need to be replaced.

Arrhythmias may be treated with medications, a procedure to treat the arrhythmias or an implantable cardioverter-defibrillator.

In addition, as with any surgery, there's a risk of infection, unexpected bleeding or blood clots.

Complications can continue throughout childhood, adolescence and adulthood for people with tetralogy of Fallot.

Ongoing care

After surgery your child will need lifelong care with a cardiologist trained in treating congenital heart disease, including routine follow-up appointments to make sure that the procedure was successful and to monitor for any new complications.

Your doctor may conduct a physical examination and order tests in regular follow-up appointments to evaluate and monitor your child's condition.

The doctor might also recommend that your child limit physical activity, particularly if there's any pulmonary valve leakage or obstruction, or arrhythmias.

Sometimes, antibiotics are recommended during dental procedures to prevent infections that might cause endocarditis — an inflammation of the lining of the heart. Antibiotics are especially important for those who have artificial valves or who've had repair with prosthetic material. Ask your child's doctor what's right for your child.

As your child grows, you might have some concerns about how best to care for him or her, including:

  • Preventing infection. A child who has severe heart defects might need to take preventive antibiotics before certain dental and surgical procedures. Your child's doctor can tell you if this is necessary. Maintaining good oral hygiene and getting regular dental checkups are excellent ways to help prevent infection.
  • Exercising and play. Parents of children who have congenital heart defects often worry about the risks of rough play and vigorous activity even after successful treatment.

    Although some children might need to limit the amount or type of exercise, many can lead normal or near-normal lives. Decisions about exercise need to be made on a case-by-case basis, so ask your child's doctor which activities are safe for your child.

If you're an adult who has congenital heart disease, you might have concerns, such as:

  • Employment. Having a congenital heart defect generally won't limit your career options. If you have serious heart rhythm problems or the potential for life-threatening complications, careers that can put others at risk — such as flying a plane or driving a bus — might be discouraged. Competitive sports are generally not suggested in people with repaired tetralogy of Fallot.
  • Pregnancy. Most women who have congenital heart disease tolerate pregnancy without any problems. However, a severe heart defect or complications such as chronic pulmonary regurgitation or arrhythmias can increase the risk of complications during pregnancy.

    If you have congenital heart disease, discuss family planning with your doctor. Your doctor may recommend that you receive care before and during your pregnancy from doctors trained in congenital heart disease, genetics and high-risk obstetric care. Some heart medications aren't safe during pregnancy and might need to be stopped or adjusted before you become pregnant.

It can be extremely frightening to learn that your child has potentially life-threatening heart defects. Although support groups aren't for everyone, talking to other parents — especially those whose children have already gone through corrective surgery — can give you hope, encouragement and support. Ask your child's doctor if there are any support groups for parents of children with heart defects in your area.

Be sure to give yourself a break at times. Ask other family members or friends to help take care of your child. When your child is in the hospital, see if you can schedule friends and family to visit with your child so that you can go home to take a shower or nap, or to spend time with your other children.

To help coordinate your child's care, you might prepare a brief note with your child's diagnosis, medications, surgeries and their dates, and the cardiologist's name and number. This note will provide necessary information to others who might care for your child and will help any new doctor understand your child's health history.

If you change health insurance plans, be sure your new plan will cover your or your child's care. Some plans might not allow coverage for pre-existing conditions or might require a waiting period.

  • Experience. Mayo Clinic doctors trained in heart conditions (cardiologists), doctors trained in treating children with heart conditions (pediatric cardiologists) and heart surgeons (cardiovascular surgeons) have extensive experience diagnosing and treating people with tetralogy of Fallot and other congenital heart diseases. Mayo doctors evaluate and treat more than 300 people each year with tetralogy of Fallot.
  • Multidisciplinary team approach. Mayo Clinic doctors in many areas work together as a multidisciplinary team to provide coordinated, comprehensive care.
  • Individualized approach. Doctors at Mayo Clinic work with you to provide exactly the care you need.
  • Congenital heart disease treatment expertise. Each Mayo Clinic location offers care for adults with tetralogy of Fallot and other congenital heart diseases.

    Doctors trained in treating adults and children with congenital heart disease work together in the Center for Congenital Heart Disease at Mayo Clinic's campus in Minnesota to treat adults and children with tetralogy of Fallot and other congenital heart diseases.

  • Surgical expertise. Mayo cardiovascular surgeons have experience and expertise treating tetralogy of Fallot and other congenital heart diseases.

    Mayo cardiovascular surgeons have experience performing intracardiac repair surgery — a procedure that improves and redirects blood flow in the heart so that blood flows in the correct direction — to treat tetralogy of Fallot.

  • Diagnostic tests. Mayo doctors have experience diagnosing tetralogy of Fallot and other congenital heart diseases with several tests.
  • Research. Mayo Clinic doctors conduct research in new diagnostic tests and treatments for tetralogy of Fallot and conduct clinical trials.

Mayo Clinic in Rochester, Minn., is ranked among the Best Hospitals for heart and heart surgery by U.S. News & World Report. Mayo Clinic also ranks among the Best Children's Hospitals for heart and heart surgery.

Mayo Clinic works with hundreds of insurance companies and is an in-network provider for millions of people. In most cases, Mayo Clinic doesn't require a physician referral. Some insurers require referrals or may have additional requirements for certain medical care. All appointments are prioritized on the basis of medical need.

Doctors trained in cardiovascular diseases and cardiovascular and thoracic surgery treat adults with tetralogy of Fallot at Mayo Clinic's campus in Arizona.

For appointments or more information, call the Central Appointment Office at 800-446-2279 (toll-free) 8 a.m. to 5 p.m. Mountain Standard Time, Monday through Friday or complete an online appointment request form.

Doctors trained in cardiovascular diseases and cardiovascular and thoracic surgery treat adults with tetralogy of Fallot at Mayo Clinic's campus in Florida.

For appointments or more information, call the Central Appointment Office at 904-953-0853 8 a.m. to 5 p.m. Eastern time, Monday through Friday or complete an online appointment request form.

Doctors trained in pediatric cardiology, cardiovascular diseases, cardiovascular surgery and others work together in the Center for Congenital Heart Disease at Mayo Clinic's campus in Minnesota to care for adults and children with tetralogy of Fallot and other congenital heart diseases.

For appointments or more information, call the Division of Cardiovascular Diseases at 507-284-3994 8 a.m. to 5 p.m. Central time, Monday through Friday, or the Division of Cardiovascular Surgery at 866-827-8810 (toll-free) from 8 a.m. to 5 p.m. Central time, Monday through Friday, or complete an online appointment request form.

Doctors trained in treating children with heart conditions (pediatric cardiologists) cardiovascular surgery and other areas work together in the Center for Congenital Heart Disease at Mayo Clinic's campus in Minnesota to care for children with tetralogy of Fallot and other congenital heart diseases.

Children with congenital heart disease are cared for in the Mayo Clinic Children's Center at Mayo Clinic's campus in Minnesota.

For appointments or more information, call the Central Appointment Office at 507-538-3270 7 a.m. to 6 p.m. Central time, Monday through Friday or complete an online appointment request form.

See information on patient services at the three Mayo Clinic locations, including transportation options and lodging.

Researchers at Mayo Clinic study new diagnostic tests and treatments for people with tetralogy of Fallot and other cardiovascular conditions. Read more about research in the Cardiovascular Research Center.

See a list of publications by Mayo Clinic doctors on tetralogy of Fallot on PubMed, a service of the National Library of Medicine.

Oct. 08, 2015