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Tetralogy of Fallot refers to a type of congenital heart defect. Congenital means present at birth.
Tetralogy of Fallot is classified as a cyanotic heart defect because the condition causes low oxygen levels in the blood. This leads to cyanosis (a bluish-purple color to the skin).
The classic form of tetralogy includes four related defects of the heart and its major blood vessels:
At birth, infants may not show signs of cyanosis. However, later they may develop sudden episodes (called "Tet spells") of bluish skin from crying or feeding.
Tetralogy of Fallot is rare, but it is the most common form of cyanotic congenital heart disease. Patients with tetraology of Fallot have a higher incidence of major non-heart congenital defects.
The cause of most congenital heart defects is unknown. Many factors seem to be involved.
Factors that increase the risk for this condition during pregnancy include:
There is a high incidence of chromosomal disorders in children with tetralogy of Fallot, such as Down syndrome and DiGeorge syndrome (a condition that causes heart defects, low calcium levels, and immune deficiency).
Zipes DP, Libby P, Bonow RO, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 8th ed. St. Louis, Mo; WB Saunders; 2007.
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