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Tetralogy of Fallot

Tetralogy of Fallot: What it is, Symptoms, Causes and Risk Factors, Diagnosis, Treatments | National Heart Centre Singapore

Tetralogy of Fallot - What it is

Tetralogy of Fallot (TOF) consists of four defects. 
  1. A hole (ventricular septal defect) between the two lower heart chambers (ventricles).
  2. There is an obstruction from the right ventricle to the lung caused by thick muscle (infundibular stenosis) and/or narrowing of the pulmonary valve (pulmonary stenosis).
  3. The aorta, which is the major artery that supplies oxygen-rich blood to the body, lies over the ventricular septal defect (overriding aorta).
  4. The muscle of the right ventricle becomes thick (right ventricular hypertrophy).

Less oxygenated ‘blue’ blood returning to the right side of the heart is mixed with the oxygenated ‘red’ blood from the left side of the heart through the hole and into the overriding aorta. Babies with unrepaired TOF are often blue. Sometimes, the pulmonary valve is also completely obstructed (pulmonary atresia).

Associated problems can include an atrial septal defect (hole between the two upper heart chambers) and abnormalities of the coronary arteries.

Common problems which can remain after repair can include:
  1. Residual pulmonary valve narrowing or leaking (Pulmonary stenosis or regurgitation)
  2. Branch pulmonary artery narrowing (Pulmonary artery stenosis)
  3. Abnormal heart rhythms (Arrhythmias)
  4. Aortic valve leaking (Aortic regurgitation

Tetralogy of Fallot - Symptoms

​You will need to come back earlier to see your doctor if you develop breathlessness, palpitations (abnormal sensation of the heart beating), lower limb swelling, syncope (fainting), giddiness or chest pain.

Tetralogy of Fallot - How to prevent?

Tetralogy of Fallot - Causes and Risk Factors

Risk factors

Activity
You may need to restrict your activity especially if your heart function is weak or there is presence of abnormal heart rhythm. Your cardiologist will determine the limitations.

Prevention of endocarditis
You will need antibiotics to prevent endocarditis (infection of the inner layer of the heart) before any dental procedures if there are residual problems after operation. Antibiotics may also be required if you should go for body piercing or tattooing. Please consult your cardiologist.

Family planning and pregnancy 
There are some associated risks with pregnancy even after TOF repair is done. Please consult your cardiologist for advice.

Additional Information
In the long term, your heart muscle function may be weakened and you may need medications. After the TOF repair, you may develop abnormal heart rhythm that can cause giddiness or fainting. Occasionally, you may need to go for another procedure to eliminate the abnormal heart rhythm if the symptoms are not well controlled with medications.

Tetralogy of Fallot - Diagnosis

Diagnosis normally starts with a physical examination by a doctor, assessing your medical history and routine tests. Other tests recommended may include:

Tetralogy of Fallot - Treatments

In early infancy, babies with TOF may need a procedure to temporarily increase blood flow to the lung (Blalock-Taussig shunt). Total surgical repair will be done later when the baby is older. In adulthood, there may be residual obstruction from the thick muscle in the right heart chambers or from the narrowed pulmonary valve. Sometimes, the pulmonary valve may become leaky (does not close properly) after the initial childhood repair. Thus, further intervention (pulmonary valve replacement) may be necessary during adulthood.

You may need to take medicine after your operation to strengthen your heart muscle contraction and to control any abnormal heart rhythm. There are various tests that may be required during follow-up appointment before decisions can be made on the need and the timing of further procedures or operations.

Tetralogy of Fallot - Preparing for surgery

Tetralogy of Fallot - Post-surgery care

Tetralogy of Fallot - Other Information

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