This general term refers to several different congenital conditions that cause an obstruction in the flow of blood through the heart. Obstruction defects include:
aortic stenosis: A stiffening of the aortic valve (the valve between the left ventricle and the aorta).
pulmonary stenosis: A stiffening of the pulmonary (or pulmonic) valve (the valve between the right ventricle and the pulmonary artery).
bicuspid aortic valve: A defect in the aortic valve, in which there are only two cusps (flaps) in the valve instead of the normal three.
subaortic stenosis: A narrowing of the left ventricle just below the aortic valve, usually from the septum.
coarctation of the aorta: A narrowing or constriction of the aorta, which obstructs blood flow from the heart to the rest of the body tissues.