Tetralogy of Fallot


Tetralogy of Fallot is a rare condition resulting from a combination of four congenital heart defects that lead to the flow out of oxygenpoor blood from the heart to the rest of the body. This causes infants and children with the condition to have a bluish tinge to their skin due to insufficient oxygen levels in their blood

The condition is typically diagnosed shortly after birth or in early childhood, although in some cases it may not be detected until adulthood depending on the severity of symptoms.

Surgery is necessary for all babies with tetralogy of Fallot, and patients may face activity restrictions and require ongoing medical care throughout their lives.


The degree of blood flow obstruction determines the specific symptoms of tetralogy of Fallot. Some warning signs and symptoms include:

  • Cyanosis, a bluish discoloration of the skin brought on by insufficient blood oxygen levels
  • Rapid breathing and shortness of breath, especially when eating or exercising
  • Clubbing, an abnormally rounded nail bed in the fingers and toes
  • Slow weight gain
  • Gets tired easily while playing or working out
  • Irritability
  • Crying for a long time
  • Heart murmur
  • Fainting

Tet spells

Tetralogy of Fallot kids can experience abrupt development of vivid blue skin, lips, and nails after crying, eating, or becoming disturbed.

Episodes of decreased blood oxygen levels in individuals with tetralogy of Fallot are commonly referred to as Tet spells“. These episodes usually occur in infants between the ages of 2 and 4 months, and are characterized by a sudden drop in blood oxygen levels. Toddlers or older children may instinctively squat during a Tet spell, as this can increase blood flow to the lungs.

If your infant exhibits any of the following signs or symptoms, get medical attention right away:

  • The skin has a blue color
  • Breathing problem
  • Weakness
  • Being irritable
  • Seizures
  • Fainting

Place your infant on his or her side and draw the knees up to the chest if he or she becomes blue (cyanotic). The lungs receive more blood as a result of this. Dial your local emergency number right away.


During pregnancy, as the baby’s heart develops, tetralogy of Fallot occurs. The cause is frequently unknown.

There are four types of defects in Tetralogy of Fallot, such as:

  • Pulmonary valve stenosis. Blood flow to the lungs is decreased when the valve separating the right ventricle, the lower right chamber of the heart, from the pulmonary artery, narrows. The muscle below the pulmonary valve may also be impacted by the constriction. Pulmonary atresia is a condition in which the pulmonary valve does not develop normally.
  • Ventricular septal defect. A hole in the septum, which divides the left and right ventricles of the heart, is referred to as a ventricular septal defect. The hole causes the right ventricle’s oxygenpoor blood to mix with the left ventricle’s oxygenrich blood. Due to this, the body receives less blood that is oxygenrich and has an inefficient blood flow. Over time, the defect may cause the heart to weaken.
  • Shifting of the aorta. In a normal heart, the aorta typically originates from the left ventricle. However, in the case of tetralogy of Fallot, there is a misplacement of the aorta. It becomes shifted towards the right side and positioned directly above the ventricular septal defect, which is a hole in the wall separating the ventricles. Consequently, the aorta receives a combination of oxygenrich and oxygenpoor blood from both the right and left ventricles.
  • Right ventricular hypertrophy. The right ventricle’s muscular wall thickens when the pumping motion of the heart is strained. This may eventually result in the heart stiffening, weakening, and failing.

In some cases, tetralogy of Fallot may occur alongside other heart conditions in both children and adults. These may include an atrial septal defect, a right aortic arch, or problems with the coronary arteries.

Risk factors

Eventhough the precise cause of tetralogy of Fallot is unknown, there are some factors that could raise the likelihood that a baby will be born with this condition. The following are risk factors for tetralogy of Fallot:

  • A viral infection like rubella (German measles), which can occur during pregnancy
  • Consuming alcohol while pregnant
  • Insufficient nutrition when pregnant
  • An elderly mother (over 40)
  • A parent suffering from tetralogy of Fallot
  • If the baby has DiGeorge syndrome or Down syndrome