Tetralogy of Fallot (fuh-LOE) is an uncommon condition involving defects within the heart structures of infants and young children. Together these defects result in oxygen-poor blood flowing out of the heart and into the body. Consequently, infants and children with tetralogy of Fallot usually have blue-tinged skin.

Tetralogy of Fallot is present at birth and usually diagnosed during infancy. However, it may not be detected until later in life, depending on the severity of the defects and symptoms. Tetralogy of Fallot occurs in about five out of every 10,000 babies. With early diagnosis followed by appropriate treatment, the majority of children with tetralogy of Fallot live into adulthood.

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

• A bluish coloration of the skin caused by blood low in oxygen (cyanosis)
• Shortness of breath and rapid breathing
• Loss of consciousness (fainting)
• Clubbing of fingers and toes (an abnormal, rounded shape of the nail bed)
• Lack of appetite
• Poor weight gain
• Tiring easily during play
• Irritability

Tet spells
Infrequently, babies with tetralogy of Fallot will suddenly develop deep blue skin, nails and lips after crying, feeding or upon awakening. These episodes are called "Tet spells" and result from a rapid drop in the amount of oxygen in the blood. Toddlers or older children may instinctively squat when they are short of breath. Squatting increases blood flow to the lungs.

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Tetralogy of Fallot

Tetralogy of Fallot involves four ("tetra") defects within the heart structures of infants and young children. Together these defects cause reduced blood flow to the lungs and mixing of blood from both sides of the heart. This results in oxygen-poor blood flowing out of the heart and into the body — usually resulting in blue-tinged skin (cyanosis) in infants and children with tetralogy of Fallot.

A problem during fetal growth
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 may increase the risk of this condition, in the majority of cases the cause of tetralogy of Fallot is unknown.

Tetralogy of Fallot is named after a doctor who described four heart abnormalities common to several of his patients in 1888. This group of abnormalities includes:

• Pulmonary valve stenosis. This is a narrowing of the pulmonary valve, the flap that separates the right ventricle of the heart from the pulmonary artery, the main blood vessel leading to the lungs. Constriction of the pulmonary valve reduces blood flow to the lungs.
• Ventricular septal defect. This is a hole in the wall that separates the two lower chambers (ventricles) of the heart. The hole allows deoxygenated blood in the right ventricle — blood that has circulated through the body and is en route 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 dilutes 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 enlarge and thicken. Over time this may cause the heart to stiffen, become weak and eventually fail.

The combined result of these abnormalities is that less blood reaches the lungs to pick up oxygen, more oxygen-poor blood is diverted into the left ventricle and the body fails to receive enough oxygenated blood.

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

• A viral illness in the mother, such as rubella (measles), during pregnancy
• Maternal alcoholism
• Poor nutrition
• A mother older than 40
• A parent who had tetralogy of Fallot

Children born with Down syndrome, a genetic condition resulting from an extra 21st chromosome, also are at increased risk of having tetralogy of Fallot.

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), immediately place your child on his or her side and pull the knees up to the chest. This helps increase blood flow to the lungs. Call 911 or your local emergency number immediately.

After your baby is born, your baby's doctor may suspect tetralogy of Fallot if the baby has blue-tinged skin or if a heart murmur — an abnormal whooshing sound caused by turbulent blood flow — is heard in your child's chest. By using several tests, your doctor can confirm the diagnosis.

• Chest X-ray. A typical sign of tetralogy of Fallot on an X-ray is a "boot-shaped" heart, because the right ventricle is enlarged.
• Complete blood count. This is a test to measure the number of each type of cell in the blood. In tetralogy of Fallot, the number of red blood cells may be abnormally high (erythrocytosis) as the body attempts to increase the oxygen level in the blood.
• Echocardiography. Echocardiograms use high-pitched sound waves, inaudible to the human ear, 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 used to diagnose tetralogy of Fallot by assessing whether a ventricular septal defect is present, the structure of the pulmonary valve, the function of the right ventricle and the position of the aorta.
• 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 (ventricular hypertrophy) and if the heart rhythm is regular.
• Cardiac catheterization. During this procedure, your doctor inserts a thin flexible tube (catheter) into an artery or vein in your baby's groin and threads it up to his or her heart. A dye is injected through the catheter to make your baby's heart structures visible on X-ray pictures. The catheter also measures pressure in the chambers of the heart and in the blood vessels.

All babies with tetralogy of Fallot need corrective surgery. Without treatment, your baby may not grow and develop properly. He or she is also at increased risk of serious complications, such as infective endocarditis, an inflammation of the inner lining of the heart caused by a bacterial infection, or stroke, caused by a blood clot in the brain.

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

Intracardiac repair
Tetralogy of Fallot treatment for most babies involves a type of surgery called intracardiac repair. This surgery is typically performed during the first year of life. During this procedure, the surgeon places a patch over the ventricular septal defect to close the hole between the ventricles. He or she also repairs 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 baby's symptoms will lessen.

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), doctors will create a bypass (shunt) between the aorta and pulmonary artery. This bypass increases blood flow to the lungs. When your baby is ready for a full repair, the shunt is removed.

After the surgery
While most babies do well after intracardiac repair, complications are possible. The most frequent are chronic pulmonary regurgitation, in which blood leaks through the pulmonary valve, and an irregular heartbeat (arrhythmia). Sometimes blood flow to the lungs is still restricted after intracardiac repair. Babies with these complications may require another surgery, and in some cases, their pulmonary valves may be replaced by artificial valves. In addition, there's a slight risk of infection, unexpected bleeding or blood clots. Arrhythmias are usually treated with medication.

Ongoing care
After surgery your baby will require continuing care. Your doctor will schedule routine checkups with your child to make sure that the procedure was successful and to monitor for any new problems.

Your doctor may also recommend that your child limit physical activity or take antibiotics during dental procedures to prevent infections that may cause endocarditis, an inflammation of the lining of the heart. Preventive antibiotics are recommended specifically for those who have artificial valves or who've had repair with prosthetic material.

While there's no known prevention for tetralogy of Fallot, it's important to follow your doctor's advice about taking care of yourself during pregnancy. Following a balanced diet and abstaining from alcohol and tobacco will increase the chances that your baby will be born healthy.

If your baby has tetralogy of Fallot, here are a few tips to help make your baby more comfortable:

• Feed your baby slowly. Also give him or her smaller, more frequent meals.
• Remain calm if your baby has a Tet spell. This will reduce your child's anxiety.
• Give yourself a break. Ask other family members or friends to help you take care of your child.

As your child grows, you may have some concerns about how best to care for your child, including:

• Preventing infection. A child with severe heart defects may need to take preventive antibiotics before certain dental and surgical procedures. Your doctor will help you learn 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 with congenital heart defects often worry about the risks of rough play and vigorous activity even after successful treatment. Although some children may need to limit the amount or type of exercise, many can lead normal or near-normal lives. Your doctor can advise you about which activities are safe for your child.

To help coordinate your child's care, you may wish to prepare a brief note with your child's diagnosis, medications, surgeries and their dates, and your cardiologist's name and number. This note will provide necessary information to others who may 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 child's care, as some plans may not allow coverage for pre-existing conditions or may require a waiting period.

If you're an adult with congenital heart disease, you may have concerns, such as:

• Employment. Having a congenital heart defect won't limit a person's career options in many cases. If an adult has serious heart rhythm problems or the potential for life-threatening complications, careers that may put others at risk may be discouraged, such as flying a plane or driving a bus.

• Pregnancy. Most women with congenital heart disease can tolerate pregnancy without any problems. However, having a severe defect or complications such as chronic pulmonary regurgitation or arrhythmias can increase your risk of complications during pregnancy.

  The risk of congenital heart disease in the general population is less than 1 percent. For children of parents with congenital heart disease, whether father or mother, this risk increases to between 2 percent and 20 percent, according to the American Heart Association. Experts recommend that anyone with congenital heart disease who is considering starting a family, carefully discuss it beforehand with his or her doctor.

  In some cases, preconception consultations with doctors who specialize in cardiology, genetics and high-risk obstetric care are needed. Some heart medications can cause serious problems for a fetus and may need to be stopped or adjusted before you become pregnant.