Tetralogy of Fallot

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Tetralogy of Fallot (TOF) is a defect that occurs at birth (congenital), though cases are said to be rare.  Tetralogy of Fallot occurs as a result of a combination of four defects of the heart which affects the flow of blood through the heart. Tetralogy of Fallot in children indicates the irregular shape of the […] Read More

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Tetralogy of Fallot

Tetralogy of Fallot (TOF) is a defect that occurs at birth (congenital), though cases are said to be rare.  Tetralogy of Fallot occurs as a result of a combination of four defects of the heart which affects the flow of blood through the heart. Tetralogy of Fallot in children indicates the irregular shape of the child’s heart during the maturation stage in the mother’s womb while pregnant. The structure of the baby’s heart deforms leading to poor oxygen intake needed to balance the normal flow of blood through the heart to the body tissues. Infants with TOF have blue-tinged skin due to inadequate oxygen.  Because tetralogy of Fallot is congenital, it can be detected and diagnosed early at birth, therefore, it is a critical congenital heart defect. Though, for some cases, tetralogy of Fallot may not be indicated until after a long period in the patient based on the symptoms experienced and how severe the symptoms are. Early diagnosis can result in rapid response for surgical procedures to treat the defects, therefore, extending the lifespan of the patient with proper medical care and follow instructions related by the doctor. As mentioned earlier, tetralogy occurs as a result of four defects present in the heart. These defects are explained below:
  • Presence of a hole located in between the double lower ventricles or chambers of the heart. This defect is known as the “Ventricular Septal Defect“. 
The hole permits the entrance of blood that has circulated the body exhausting its oxygen (deoxygenated blood) into the right ventricle to then flow through to the left ventricle and makes contact with the already fresh oxygenated blood originating from the lungs. Therefore, the mixture of the fresh oxygenated and deoxygenated blood moves to the right ventricle improperly. This decreases the supply of oxygenated blood through the body and will deplete the heart’s capacity to function properly.
  • Reduction in the size of both the pulmonary valve and artery. This valve is responsible for the separation of the right ventricle in the lower right chamber from the pulmonary artery i.e main blood vessel linked to the lungs. This defect is called Pulmonary Stenosis“. 
Constriction in the pulmonary valve affects the system by reducing the flow of deoxygenated blood to the lungs for replenishing the oxygen in the blood. In some cases, pulmonary stenosis can be a result of irregularities in the pulmonary valve known as pulmonary atresia which affects the flow rate of the blood to the lungs.
  • When the right ventricles in the lower chamber of the heart are affected, the muscular walls in the ventricle become thicker than usual. This condition is referred to as “Ventricular Hypertrophy“.
The thickness of these muscular walls of the right ventricle is a result of overworking the heart’s pump rate which leads to gradual stiffness of the heart, reducing the capacity and causing the heart to fail.
  1. When the valve in the aorta known as the aortic valve opens from the two ventricles for the flow of blood instead of the ventricle in the left lower chambers alone and has an irregular increase in the aortic valve. It is noted as a defect and the aortic valve will be located above the ventricular septal defect leading to a double entrance of blood from the left and right ventricles.
TETRALOGY OF FALLOT RISK FACTORS As the cause of tetralogy of Fallot is not known, risk factors involved in the tetralogy of Fallot are:
  1. Intake of alcohol for pregnant women is bad.
  2. Malnutrition during pregnancy can affect the fetus.
  3. Diseases like rubella can prompt the tetralogy of Fallot.
  4. Women aged 40 years and above are liable to have tetralogy of Fallot.
  5. History of tetralogy of Fallot in the family.
  6. History of down’s syndrome or DiGeorge syndrome.
TETRALOGY OF FALLOT COMPLICATIONS Infants with tetralogy of Fallot require surgery as staying without treatment can be detrimental to the health of the infant causing stunted growth or irregular growth. Also, infants with tetralogy of Fallot have a high risk of contracting arrhythmia due to irregularities in heartbeats or endocarditis caused by a bacterial infection. All resulting in possible death. TETRALOGY OF FALLOT DIAGNOSIS Tetralogy of Fallot diagnosis is performed both during the maturation stage of the fetus or after the child is born. In the pregnancy phase of the woman, prenatal tests are conducted usually to observe for any possible defects or conditions in the baby. Therefore, proper screening can lead to the discovery of tetralogy of Fallot if present in the baby.  These screening tests can be conducted with the aid of the ultrasound which shows clear images of the body which will surely aid the specialist in diagnosing a possible tetralogy of Fallot in the baby.  Any sign detected results in conducting further tests by utilizing a fetal echocardiogram (EKG) to screen the baby to conclude the presence of a possible tetralogy of Fallot. The echo diagram screens the heart of the fetus and examines the heart structure and the operation of the heart even with the defect. Also, tetralogy of Fallot can be diagnosed even after the baby is born as the color of the skin i.e deep blue when agitated, eating, or crying can indicate the presence of tetralogy of Fallot. Further tests are conducted on the baby and the presence of a heart murmur or bluish-looking skin is checked. This test is known as the echocardiogram and it indicates the ultrasound of the heart and monitors the health of the baby over some time. Thereafter, a screening device known as pulse oximetry can be used to observe the quantity of oxygen in the blood of the infant. A reduced level of oxygen in the blood indicates a possible  “Critical Congenital Heart Defect”. TETRALOGY OF FALLOT PREVENTION There is no knowledgeable form of preventing the tetralogy of Fallot. TETRALOGY OF FALLOT TREATMENT Due to the severity of the defect, a surgical repair procedure is required to treat the baby.  This tetralogy of Fallot surgery involves the replacement of the pulmonary valve to increase the passageway to the pulmonary artery responsible for the migration from the blood vessel to the lungs. Also, patches will be made on the holes in the muscular walls of the lower chambers of the ventricles to numb the ventricular septal defect. This will optimize the flow of blood through the whole body. TETRALOGY OF FALLOT LIFE EXPECTANCY Infants tend to live healthy lives after the surgery has been performed successfully though regular check-up is mandatory to monitor the success rate and any other complications. The mortality rate is low due to the success of the surgery, but other heart conditions may arise mainly due to complications like arrhythmia. Normally, a patient who has been treated can live for many years but the constraints of arrhythmias limit the life span to 20 to 37 years after surgery.



Tetralogy of Fallot symptoms is dependent on the severity of the obstruction of the flow of blood between the chambers in the heart and lungs. 

Signs and symptoms involved with tetralogy of Fallot include:

  1. Dizziness and fainting.
  2. Hard breaths mostly during exercises or eating.
  3. The coloration of the skin due to deoxygenated blood is known as cyanosis.
  4. Weight reduction.
  5. Irritation.
  6. Heart murmur.
  7. Fatigue
  8. Regular clubbing of the toes and fingers.
  9. Persistent crying.

For infants, the skin comes out as blue-tinged or even the nails when feeding or agitated. This occurs in infants with the age group of 2 to 4 months. These are known as the “Tet Spell”.



Tetralogy of Fallot tends to occur during the growth of the fetus. Many factors influence this defect ranging from malnutrition, consumption of the mother or medications are taken, illness, a disorder in the genes but generally, the main cause of tetralogy of Fallot can not be pinpointed.


  • What causes cyanosis in the tetralogy of Fallot?
  • Cyanosis occurs as a result of low oxygen levels in the blood which is attributed to ventricular septal defect. Therefore, when a patient has tetralogy of Fallot, a low oxygen level in the blood is imminent resulting in cyanosis.

    • What is the most common complication found in patients with tetralogy of Fallot?

    The arrhythmias are the most common complication acquainted with tetralogy of Fallot as it is responsible for the death that occurs later after a period of 20 to 37 years of survival.

    • What are the four components of tetralogy of Fallot?

    The four defects that result in the tetralogy of hearts are the ventricular septal defect, pulmonary stenosis, overriding aorta, and ventricular hypertrophy.

    • How long can you live with the Tetralogy of Fallot?

    Normally, a patient who has been treated can leave for many years but the constraints of arrhythmias limit the life span to 20 to 37 years after surgery.

    • What 3 foods cardiologists say to avoid?

    Foods like dessert, potato chips, bacon, meals with excess protein, and energy drinks should be avoided.