What is aortic stenosis?

Aortic stenosis is a heart defect that may be congenital (present at birth) or acquired (develop later in life). If the problem is congenital, then something occurred during the first 8 weeks of pregnancy to affect the development of the aortic valve. The aortic valve is found between the left ventricle and the aorta. It has three leaflets that function like a one-way door, allowing blood to flow forward into the aorta, but not backward into the left ventricle.

Aortic stenosis is the inability of the aortic valve to open completely. With aortic stenosis, problems with the aortic valve make it harder for the leaflets to open and permit blood to flow forward from the left ventricle to the aorta. In children, these problems can include a valve that:

  • Only has two leaflets instead of three (bicuspid aortic valve).
  • Has leaflets that are partially fused together.
  • Has thick leaflets that do not open all the way.
  • Becomes damaged by rheumatic fever or bacterial endocarditis.
  • Area above or below the valve is narrowed (supravalvar or subvalvar).
  • Aortic stenosis may be present in varying degrees, classified according to how much obstruction to blood flow is present.

A child with severe aortic stenosis will be quite ill, with major symptoms noted early in life. A child with mild aortic stenosis may have few symptoms, or perhaps none until later in adulthood. The degree of obstruction can become worse with time. Congenital aortic stenosis occurs in 4 to 6 percent of all children with congenital heart disease. Relatively few children are symptomatic in infancy, but the incidence of problems increases sharply in adulthood. Congenital aortic stenosis occurs three times more often in boys than in girls.