There are two types of heart conditions that can affect children - congenital and acquired. Congenital heart diseases/conditions are those that are present from birth, either as a result of heredity or environmental influences. Acquired heart diseases/conditions are developed with time, and are not present at birth.

There are thousands of children born annually with congenital heart conditions. According to the American Heart Association, of the children born with congenital heart conditions,
4-10 percent have atrioventricular septic defect,
8-11 percent have coarctation of the aorta,
9-14 percent have tetralogy of Fallot, 
10-11 percent have transposition of the great arteries, 
14-16 percent have ventricular septal defects, and
4-8 percent have hypoplastic left heart syndrome.

The children that develop acquired heart conditions can have diseases including arrythmias, cardiomyopathies, Kawasaki disease, rheumatic fever, familial hypercholesterolemia, and/or AIDS with its myocarditis.