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When Your Child Has Tetralogy of Fallot (TOF)

Front view cross section of heart showing atria on top and ventricles on bottom showing aorta, pulmonary artery, mitral valve, aortic valve, left atrium, left ventricle, right atrium, right ventricle, tricuspid valve, pulmonary valve, superior vena cava, and inferior vena cava. Arrows on right side of heart show oxygen-poor blood pumping to lungs. Arrows on left side of heart show oxygen-rich blood pumped to body.

Front view cross section of heart showing Tetralogy of Fallot: aorta above both ventricles (overriding), pulmonary stenosis, ventricular septal defect (VSD), and thickened right ventricle (hypertrophy). Arrows show blood flowing from left and right sides of heart through VSD to mix and be pumped out of aorta. Some blood flows from right side of heart to pulmonary artery.

Your child has been diagnosed with tetralogy of Fallot (TOF). This is a complex heart defect. While TOF is a serious heart condition, it can be repaired with surgery.

The Normal Heart

  • The heart is divided into four chambers. The two upper chambers are called atria. The two lower chambers are called ventricles. The heart contains four valves. The valves open and close to keep blood flowing forward through the heart.

  • In a normal heart, oxygen-poor blood returning from the body fills the right atrium. This blood flows through the tricuspid valve into the right ventricle. The right ventricle pumps this blood through the pulmonary valve into the pulmonary artery. The pulmonary artery sends this blood to the lungs to receive oxygen. Oxygen-rich blood returning from the lungs fills the left atrium. This blood flows through the mitral valve into the left ventricle. The left ventricle pumps this blood through the aortic valve into the aorta. The aorta sends this blood to deliver oxygen to the body.

What Is Tetralogy of Fallot?

A child with TOF has the following group of structural heart problems:

  • Pulmonary stenosis (PS): Narrowing of the pulmonary valve or area below the valve. This causes an obstruction (blockage) to blood flow from the heart to the lungs.

  • Ventricular septal defect (VSD): A hole in the dividing wall (ventricular septum) between the ventricles.

  • Right ventricular hypertrophy: Thickened right ventricle.

  • Overriding aorta: Aorta that is shifted toward the right side of the heart. This causes it to sit over or “override” the ventricles above the ventricular septum.

Why Is Tetralogy of Fallot a Problem?

  • With TOF, oxygen-poor blood from the right ventricle may flow through the VSD and mix with oxygen-rich blood in the left ventricle. This is called a right-to-left shunt. The mixed blood (blood with some oxygen) is then pumped through the aorta to the body. Because this blood contains less oxygen than normal, it causes your child’s skin, lips, and nails to appear blue. This condition is called cyanosis. Cyanosis worsens if there is decreased blood flow to the lungs caused by severe PS.

  • A child with TOF may have sudden episodes (tetralogy or “tet” spells) in which there is severely decreased blood flow to the lungs. During a tet spell, your child may become irritable, cry, or turn blue. He or she may even faint or have a seizure.

What Causes Tetralogy of Fallot?

TOF is a congenital heart defect. This means it’s a problem with the heart’s structure that your child was born with. The exact cause of this problem is unknown, but children with certain genetic abnormalities are more likely to have TOF.

What Are the Symptoms of Tetralogy of Fallot?

Symptoms can include:

  • Cyanosis

  • Trouble breathing

  • Trouble feeding

  • Poor growth

  • Irritability

  • Tet spells

If Your Child Has a Tet Spell

  • To help force blood to the lungs, move your child’s knees toward his or her chest. With a baby, place the baby over your shoulder (as you would when burping your baby) with the knees curled toward the chest. With a toddler or older child, have the child lie on the side on a flat surface with knees up to chest. Do not be surprised if your toddler or older child squats instinctively when having a tet spell. This also helps force blood to the lungs.

  • Call your child’s healthcare provider or 911 immediately. You may need to take your child directly to the ER.

  • A tet spell is often a sign that it is time for your child’s heart surgery. Medications may be prescribed for your child to help manage spells until surgery can be done to repair the defect.

  • Parents should know how to perform CPR to help their child during spells in which the child may stop breathing.

How Is Tetralogy of Fallot Diagnosed?

  • TOF may be detected with fetal echocardiography (fetal ultrasound) before a child is born. This test uses sound waves to form a picture of the baby’s heart. This test can be done when the mother is at least 16 weeks pregnant.

  • If TOF isn’t detected before birth, signs of a heart problem may be found during a physical exam after the child is born.

  • If a heart problem is suspected, your child will be referred to a pediatric cardiologist (doctor who diagnoses and treats heart problems in children). To confirm a diagnosis of TOF, several tests may be done. These include:

    • Chest x-ray: X-rays are used to take a picture of the heart and lungs.

    • Electrocardiography (ECG or EKG): The electrical activity of the heart is recorded.

    • Echocardiography (echo): Sound waves are used to create a picture of the heart and look for structural defects and other problems.

    • Pulse oximeter or oxygen saturation test: The oxygen level in the blood is measured.

How Is Tetralogy of Fallot Treated?

  • A child with TOF requires heart surgery to correct the heart defects. Surgery may be done when your child is 3–5 months old. If symptoms aren’t severe, surgery may not be done until a child is 1–2 years old.

  • In rare cases, a temporary procedure may be needed to increase blood flow to the lungs until complete repair can be done. Your child may also need a cardiac catheterization procedure to gain additional information or to widen the pulmonary valve before having surgery. To widen the valve, a special balloon catheter (thin, flexible tube) is used to stretch the valve open. Your child’s cardiologist will tell you more about this, if needed.


Risks and Possible Complications of Heart Surgery for TOF Include:

  • Reaction to sedative or anesthesia

  • Valve insufficiency (leakage of blood through the pulmonary valve back into the right ventricle)

  • Arrhythmia (abnormal heart rhythm)

  • Problems in the lungs

  • Infection

  • Bleeding

  • Problems with the nervous system

  • Abnormal buildup of fluid around the heart or lungs

What Are the Long-term Concerns?

  • Regular follow-up visits with the cardiologist are needed for the rest of your child’s life. Further pulmonary valve treatment may be needed in the future. Your child may also develop heart rhythm problems that may need to be treated.

  • After repair of TOF, most children can be active. The level and extent of physical activity will vary with each child. Check with the cardiologist about what activities are appropriate for your child.

  • Your child may need to take antibiotics before having any surgery or dental work. This is to prevent infection of the inside lining of the heart and valves. This infection is called infective endocarditis. Antibiotics should be taken as directed by the cardiologist.


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