Stenosis means constriction or narrowing. Subaortic means below the aorta. Subaortic stenosis refers to a narrowing of the left ventricle just below the aortic valve, which blood passes through to go into the aorta. This stenosis limits the flow of blood out of the left ventricle. This condition may be congenital or may be due to a particular form of cardiomyopathy known as "idiopathic hypertrophic subaortic stenosis" (I.H.S.S.). Treatment depends on the cause and the severity of the narrowing. It can include drugs or surgery. Check with your pediatric cardiologist about limiting some kinds of exercise.
People with subaortic stenosis, before and after treatment, are at risk for getting an infection within the aorta or the heart valves (endocarditis). To help prevent this, they'll need to take antibiotics before certain dental and surgical procedures.