Dayton Children’s Hospital

Tetralogy of Fallot

What is tetralogy of Fallot?

Babies diagnosed with tetralogy of Fallot (TOF) are born with a rare, complex heart defect. It occurs in about 5 out of every 10,000 babies and affects boys and girls equally. The exact cause is unknown.

There are generally four heart abnormalities involved in TOF:

  1. Ventricular septal defect: a hole in the septum between the heart’s two lower chambers
  2. Pulmonary valve stenosis: narrowing of the pulmonary valve
  3. Right ventricular hypertrophy: a thickening of the muscle of the right ventricle
  4. An overriding aorta: incorrect positioning of one of the body’s main arteries
tetralogy of fallot

Blood flow with tetralogy of fallot

Normal heart blood flow

Normal heart blood flow


How is TOF diagnosed?

Babies who have TOF have low oxygen levels in the blood, which leads to cyanosis (a bluish-purple color to the skin, lips and fingernails). In addition to cyanosis, you may notice your baby having difficulty with feeding. Symptoms normally occur in the first few weeks of life.

While examining your baby, the doctor will first listen for a heart murmur with a stethoscope. If your doctor hears a murmur and your baby is showing some symptoms of TOF, any or all of the following tests may be done to confirm the diagnosis:

  • Chest X-ray: a painless test that creates pictures of the heart and lungs
  • Complete blood count: a blood test
  • Echocardiogram: a painless test that uses sound waves to create a moving picture of the heart
  • Electrocardiogram (EKG): a painless test that records the heart’s electrical activity
  • Pulse oximetry: a painless test that shows how much oxygen is in the blood
  • Cardiac catheterization: A procedure where a thin, flexible tube is inserted through a large artery and into the heart allows your doctor to see the flow of blood through your baby’s heart and blood vessels on an X-ray image.

How is TOF treated?

Babies diagnosed with TOF will require open-heart surgery to repair all four abnormalities so that the heart can work as normally as possible. The surgery is usually done soon after birth or while your baby is very young. Sometimes more than one surgery is needed. Babies who have continued, severe leakiness of the pulmonary valve may need to have doctors replace the valve.

How will TOF affect my baby during and after surgery?

During surgery, your baby will be given general anesthesia, which means the baby will be comfortable and sleeping. After surgery, your baby will need to stay in a cardiac intensive care unit (CICU) for the first few days and may be connected to several tubes and wires to allow your baby’s doctor to best monitor the baby’s condition. Pain control will be used to make sure your baby is comfortable.

Most of the tubes and wires will be disconnected before your baby leaves the CICU, after which he or she will spend several more days in the hospital in a step down unit.

Most cases of TOF can be corrected with surgery, although your baby will need regular follow-up visits with a cardiologist. More than 90 percent of babies who have surgery for TOF go on to live healthy lives.

Photo credit: Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities.