What is Tetralogy of Fallot (TOF)?

Tetralogy of Fallot (TOF) (pronounced te-tral-uh-jee of Fal-oh), one of the most common congenital heart disorders, comprises right ventricular (RV) outflow tract obstruction (RVOTO) (infundibular stenosis), ventricular septal defect (VSD), aorta dextroposition (overriding aorta), and RV hypertrophy. The mortality rate in untreated patients reaches 50% by age 6 years, but in the present era of cardiac surgery, children with simple forms of tetralogy of Fallot enjoy good long-term survival with an excellent quality of life

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

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’s the most common cyanotic congenital heart disease.

Symptoms of Tetralogy of Fallot (TOF)

The symptoms of TOF may be present at birth or shortly afterward. They include:

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

Causes and Risk factor of Tetralogy of Fallot (TOF)

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

  • maternal alcoholism
  • diabetes
  • maternal age that’s over 40
  • poor prenatal diet

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

Diagnosis of Tetralogy of Fallot (TOF)

Sometimes, a doctor will diagnose TOF while the baby is still in the mother’s uterus when a fetal ultrasound displays a heart abnormality. Your doctor can also diagnose it shortly after birth if they hear a murmur during a heart exam or if the baby’s skin color is bluish.


People most often receive a diagnosis in infancy, but if the defects aren’t severe, the symptoms may be minimal. This can delay diagnosis. Other times, the diagnosis comes later, such as when a parent notices something abnormal or during a regular visit to the pediatrician.

Tests that can aid in the diagnosis of TOF are:

  • a chest X-ray to check for structural abnormalities
  • an echocardiogram to check for disruptions in heartbeats
  • a heart MRI to check for structural problems
  • a pulse oximetry test to measure the oxygen level in the blood
  • a cardiac catheterization

Treatment of Tetralogy of Fallot (TOF)

Treatment of TOF requires surgery. This usually occurs within the first few months of life. The surgery includes closing the VSD and enlarging the pulmonary valve. According to the Children’s Hospital of Philadelphia, if doctors can’t perform a complete repair, they’ll perform a temporary repair until a complete surgery is possible.

If TOF is left untreated, it 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, a doctor will notice the condition early on and perform surgery to correct the problem.

After having surgery for TOF, a person will need to see a cardiologist for the rest of their 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.