Tetralogy of Fallot (TOF)

Written by Jaime Herndon | Published on August 7, 2012
Medically Reviewed by George Krucik, MD

What is Tetralogy of Fallot?

The main function of your heart is to pump blood through the rest of the body. This blood gives your body nutrients and oxygen. If your heart does not work properly, it may not be efficient in pumping blood to other organs, which affects the amount of oxygen getting to other bodily tissues. Sometimes there are defects or problems with the heart when a person is born; such a defect is called a congenital heart defect.

Tetralogy of Fallot is a congenital heart defect that can be fatal if left untreated. It is also known as TOF or Tet. The name of the condition comes from the four problems associated with it (tetra), and the physician for which it is named, Dr. Etienne Fallot.

The four heart defects associated with TOF are:

  • a hole between right and left ventricles, also called ventricular septal defect
  • narrow pulmonary outflow tract; this connects the heart with the lungs
  • right ventricle thickening
  • an aorta that is shifted in its orientation and lays over the ventricular septal defect

The condition causes cyanosis. This means it causes the skin to have a bluish hue due to the lack of circulating oxygen. Typically, oxygenated blood gives the skin its pinkish hue.

TOF is rare, but it is the most common cyanotic congenital heart disease.

What Causes TOF? Who Is at Risk?

The exact cause of TOF is unknown, but several risk factors have been associated with the condition. These include:

  • maternal alcoholism
  • diabetes
  • advanced maternal age (over 40)
  • poor prenatal diet

Individuals with TOF often have other congenital disorders such as Down syndrome.

What Are the Symptoms of TOF?

Symptoms of the condition are present at birth, and can include:

  • bluish skin color
  • clubbed fingers, or growths of skin and bone around the fingernails
  • problems with eating and failure to gain weight
  • developmental delays or problems
  • episodes of passing out

How Is TOF Diagnosed?

Sometimes TOF is diagnosed while the baby is still in utero, when a fetal ultrasound displays a heart abnormality. It may also be diagnosed shortly after birth, if a murmur is heard during a heart exam, warranting further tests, or if the baby’s skin color is bluish. The condition is most often diagnosed in infancy, but if the defects are not severe, symptoms may be minimal, causing diagnosis to be delayed. Other times, the diagnosis comes later, when a parent has noticed something abnormal, or during a regular pediatrician visit.

Tests that can aid in the diagnosis of TOF are:

  • chest X-ray, to show structural abnormalities
  • echocardiogram, which shows disruptions in heartbeats
  • heart MRI to check for structural problems
  • pulse oximetry, which measures oxygen in the blood
  • cardiac catheterization

How Is TOF Treated?

Treatment of TOF requires surgery. This is usually done within the first few months of life. The surgery includes closing the ventricular septal defect and enlarging the pulmonary valve. According to the Children’s Hospital of Philadelphia, if doctors cannot perform a complete repair, a temporary repair will be done until a complete surgery is possible.

More than 90 percent of children who undergo surgery for TOF will survive to be adults and lead healthy, normal lives (NIH).

Left untreated, TOF can cause problems with heart rhythms, developmental delays, and seizures. If the condition is never fixed, which is rare, it typically causes death by the age of 20 years old. Usually the condition is caught early on and surgery is performed to correct the problem.

Once surgery is performed, an individual will need to see a cardiologist for the rest of his or her life. A cardiologist will perform regular follow-up exams and consult with the person’s primary care physician on any medications or health problems that are present. Some people who have surgery for TOF develop heart problems as time goes on, which makes consistent and continuous care important.

Long-Term Outlook: Living With TOF

Sometimes individuals who have been treated for TOF will need to limit their exercise. Talk with your doctor about whether this is necessary. If you really want to be physically active, ask your doctor what would be a safe activity for you.

Take any medication your doctor prescribes as necessary. If you start to take any other medications or supplements, let your doctor know in order to avoid any adverse interactions or effects.

You can still lead a normal and productive life if you have been treated for TOF. Seeing your doctor regularly will help catch any problems before they become serious and ensure you are staying healthy.

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