Tetralogy of Fallot

A congenital cyanotic heart defect is a congenital heart disorder in which deoxygenated blood bypasses the lungs and enters the circulatory system, or where there is a mixture of oxygenated and deoxygenated blood entering the system. It is caused by structural defects in the heart such as bidirectional shunting, or the incorrect position of the pulmonary artery or the aorta, or any condition that increases pulmonary vascular resistance. The result is the development of collateral circulation.

Description

Symptoms

Children with this heart condition will have the following symptoms:

A tendency towards desaturation (80% to 90%), depending on the presence of patent ductus arteriosus or the degree of obstruction in the lung.
Severe stenosis, close to pulmonary atresia
Cyanotic episodes which correspond with infundibular spasms that decrease lung flow, and which are relieved if the sufferer assumes a squatting position.

Who is affected by Tetralogy of Fallot?

Tetralogy of Fallot makes up 10% of all congenital heart disorders and is considered the most common cyanotic heart disease. There are around 400 cases for every million births.

Diagnosis

Diagnosis is confirmed via 2D echocardiogram.

Typical treatment

Repair is carried out around six months old. If the baby suffers a episode before the defect has been corrected, treatment is started in the form of beta blockers to reduce lung spasms.

If very severe cyanotic episodes persist in babies under six months despite this treatment, then palliative surgery needs to be performed to take blood to the lungs. This surgery consists of making a connection between a systemic artery and the pulmonary arteries (a systemic-pulmonary fistula).

The definitive corrective surgery involves closing the ventricular septal defect with a patch and widening the outlet from the right ventricle.

In cases of severe pulmonary insufficiency there is progressive dilatation of the right ventricle in the long term. If this becomes excessive, it is necessary to replace the valve. Risk of lung valve replacement is around 20% after 25 years.