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Tetralogy of Fallot (cont.)

Tetralogy of Fallot Causes

Tetralogy of Fallot occurs during development of the fetus, before birth, and is therefore termed a congenital birth defect. An error occurs as the fetal heart separates into the chambers, valves, and other structures that make up the normal human heart. No one is really sure why this error occurs.

Tetralogy of Fallot Symptoms

Most infants with tetralogy of Fallot develop cyanosis in the first year of life.

  • The skin, lips, and mucous membranes inside the mouth and nose take on a noticeably dusky blue color.
  • Only some infants with very severe obstruction of the right ventricle outflow turn blue at birth.
  • A small number of children with tetralogy of Fallot never turn blue at all, especially if the pulmonary stenosis is mild, the ventricular septal defect is small, or both.
  • In some children, the cyanosis is quite subtle and may go undetected for some time.

The following symptoms suggest tetralogy of Fallot:

  • Growth and development are slower, especially if the pulmonary stenosis is severe. Puberty may be delayed if the tetralogy is untreated.
  • The child usually tires easily and begins panting with any form of exertion. He or she may play for only a short time before sitting or lying down.
  • Once able to walk, the child often assumes a squatting position to catch his or her breath and then resumes physical activity. Squatting increases the pressure transiently in the aorta and left ventricle, causing less blood to move into the left ventricle, more out the pulmonary artery to the lungs.

Episodes of extreme blue coloring (called hypercyanosis or simply "tet spells") occur in many children, usually in the first 2-3 years of life.

  • The child suddenly becomes blue, has difficulty breathing, and may become extremely irritable or even faint.
  • Many children with tetralogy of Fallot experience these spells.
  • The spells often happen during feeding, crying, straining, or on awakening in the morning.
  • Spells can last from a few minutes to a few hours.
Medically Reviewed by a Doctor on 1/8/2016
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