Tetralogy of Fallot

What is Tetralogy of Fallot?

Tetralogy of Fallot (teh-tral-uh-jee of fah-low) is a rare congenital heart defect where four specific heart defects occur together and impact the flow of blood through the heart.

What are the four defects of Tetralogy of Fallot?

The four heart defects of Tetralogy of Fallot are:

• ventricular septal defect, or ‘hole in the heart’
• pulmonary stenosis, which causes narrowing of the pulmonary valve between the heart and the lungs
• right ventricular hypertrophy, where the wall of the right ventricle is thicker than normal
• overriding aorta, where the biggest artery in the body, the aorta, is positioned over the ventricular septal defect instead of the left ventricle

What are the symptoms of Tetralogy of Fallot?

Symptoms of Tetralogy of Fallot can vary in severity and often get worse over time if not treated.

One of the most common symptoms of Tetralogy of Fallot is cyanosis, bluish or greyish skin, nails or lips that begins very soon after birth and which is caused by a lack of oxygen in the blood. Sudden and rapid drops in oxygen during feeding or crying can also cause ‘tet spells’.

Other symptoms of Tetralogy of Fallot include:

• a heart murmur
• trouble breathing
• weakness
• fatigue
• irritability
• fainting
• seizures

What causes Tetralogy of Fallot?

Tetralogy of Fallot and its associated defects occur during pregnancy when the baby’s heart is developing.

The causes of these defects are mostly unknown, but may include genetic causes or environmental factors during pregnancy.

How is Tetralogy of Fallot diagnosed?

Tetralogy of Fallot is mostly diagnosed either during pregnancy or soon after birth.

Tests to diagnose Tetralogy of Fallot may include:

• pulse oximeter, which measures how much oxygen is in the blood
• echocardiogram (echo)
• electrocardiogram (ECG)
• chest x-ray
• cardiac catheterisation

How is Tetralogy of Fallot treated?

Treatment for Tetralogy of Fallot involves surgery to fix the defects and improve blood flow through the heart.

The surgical options are:

• temporary repair – when a baby is too weak or small for open heart surgery, a shunt, or tube, may be used to create a new temporary path for blood to travel from the heart to the lungs
• open heart surgery or complete repair – this involves improving blood flow to the lungs by patching the ventricular septal defect, the ‘hole in the heart’, and widening or replacing the pulmonary valve

How can Tetralogy of Fallot be prevented?

As the causes of Tetralogy of Fallot are mostly unknown, prevention may not be possible.

It is however advisable to reduce the risk of Tetralogy of Fallot by taking the following steps:

• not drinking alcohol or smoking during pregnancy
• ensuring diabetes is well managed during pregnancy
• being vaccinated against rubella more than 28 days before pregnancy
• talking to your doctor about what medications may not be appropriate during pregnancy
• ensuring adequate nutrition during pregnancy