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Tetralogy of Fallot    See images

Overview | Symptoms | Treatment | Prevention

Definition:

A congenital defect of the heart consisting of 4 abnormalities that results in insufficiently oxygenated blood pumped to the body.

Causes and Risks

The cause of most congenital heart defects is unknown. They are usually caused by multiple factors. Prenatal factors associated with higher than normal incidence of the disease include maternal rubella or other viral illnesses during pregnancy, poor prenatal nutrition, maternal alcoholism, mother over 40 years old, and diabetes. There is a higher incidence of Tetralogy of Fallot in children with Down syndrome.

Tetralogy of Fallot is classified as a cyanotic heart defect because the condition results in insufficiently oxygenated blood pumped to the body, which leads to cyanosis (a bluish-purple coloration to the skin) and shortness of breath. The classic form of Tetralogy includes 4 defects within the heart structures: ventricular septal defect (hole between the right and left ventricles); narrowing of the pulmonic valve; overriding aorta; and thickened wall of the right ventricle (right ventricular hypertrophy).

There is flow of deoxygenated blood into general circulation, and a decreased blood flow to the lungs, which compounds the cyanotic condition. At birth, infants may not show the signs of the cyanosis but later may develop episodes of bluish skin from crying or feeding (called "Tet spells"). Tetralogy of Fallot occurs in approximately 50 out of 100,000 infants. It is the 2nd most common cause of congenital cyanotic heart disease in infants.

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