Fallot - tetralogy

As the name suggests, ‘Tetralogy of Fallot’ is a heart defect caused by a combination of four problems. It is a rare condition which is present at the time of birth of the child (i.e. congenital condition). In this condition, the heart structure is affected, and it cannot function properly. Therefore, the oxygen supply to the body parts is inadequate. If it is not treated immediately, it can become fatal.

The clinical features of Tetralogy of Fallot depend on the severity of the defects.

Most often the following symptoms and signs are displayed in infants:

  • Difficulty in feeding
  • Failure to thrive
  • Exertional dyspnea which usually worsens with age
  • Bluish-pale skin while crying or feeding which occurs in episodes (‘tet spells’)

Physical findings of the infant include:

  • Smaller size of the infant than the age due to poor development
  • Poor weight gain
  • Cyanosis of lips and nails usually more prominent at childbirth
  • After 3-6 months of birth, clubbing of fingers and toes occurs

The exact cause of the congenital diseases is not known.

The four defects which affect the structure and function of the heart are:

  • Thickening of the muscles surrounding the lower right chamber
  • Obstruction of the blood vessel connecting heart to the lungs
  • The aorta (blood vessel) lies above the hole in the lower chambers (misplaced)
  • A hole in the wall separating the lower chambers

Certain factors which may increase the risk of the child getting Tetralogy of Fallot are:

  • Poor nutrition during pregnancy
  • Alcohol consumption by the mother
  • Mother who has crossed 40 years of age
  • Diabetes in the mother
  • Viral infections such as rubella in the mother

If Tetralogy of Fallot is not treated, it can cause the below complications

  • Problems with the heart rhythm
  • A delay in the development of the baby
  • Seizures (fits)
  • Death (if the condition is never fixed, which is rare)

Usually, the diagnosis of Tetralogy of Fallot is made soon during infancy. However, if the symptoms are not severe, then the condition may not be detected until later stages of life. An early diagnosis can help in a better treatment to allow the child to lead a normal life with certain restrictions on exercises.

The below medical tests are performed to check if the child has Tetralogy of Fallot:

Test Purpose of the test
Hemoglobin & hematocrit To understand the degree of cyanosis Elevation of the levels due to cyanosis
Electrocardiogram Measures the electrical activity of the heart Detects the structural abnormalities in the heart
Chest X-ray Shows an abnormal aorta and a boot-shaped heart due to enlarged right lower chamber
Echocardiography Demonstrates septal defects, the degree of pulmonary stenosis, hole in the wall, etc.
Bleeding tendency Reduced clotting factors, platelet count, and total fibrinogen Prolonged prothrombin time and coagulation time.
Cardiac catheterization To obtain X-ray images through a catheter (a small tube) inserted into the blood vessel and advanced into the heart To detect ventricular septal defects, pulmonary stenosis, size of the pulmonary arteries, overriding aorta

Doctors can usually identify the Tetralogy of Fallot defect early at the child’s birth and surgically repair it. Children with a simple form of Tetralogy of Fallot can have a quality of life with good life expectancy.

Surgery is the main treatment option for correcting the defects. The corrective is performed in the younger infants to widen the pulmonary tract and improve the blood flow to the lungs. Surgery is usually performed within 2 years of birth. Sometimes more than one surgery is needed.

The child will be given oxygen through a mask to increase the oxygen levels in the blood.

To decrease the severity of tet spells, the child may be given medications such as morphine, propranolol or metoprolol, or, in severe cases, phenylephrine.

People with Tetralogy of Fallot should follow certain precautions as provided below:

  • They have to restrict doing certain exercises as suggested but the doctor
  • Take medications as prescribed by your doctor
  • Should not take any additional medications without notifying your doctor
  • Get your health checked by your doctor regularly