Question Title: Subaortic membrane stenosis

Thanks-May the force be with you.

Subaortic stenosis, also called subvalvular aortic stenosis, is a genetic trait more common in men than in women by 2:1. It consists of a narrowing (stenosis) in the outflow area of the heart below the aortic valve. There are three types of subaortic stenosis. 1. A fibrous ring - this is a discrete fibrous membrane below the valve. It may extend onto the mitral leaflet and may attach to the aortic cusps. 2. Tunnel type - a complete circle, or tunnel below the valve that usually involves hypoplasia (small growth) of the aortic valve. 3. Muscular type - thickening of the heart muscle (also called hypertrophic cardiomyopathy or HOCM).

Subaortic stenosis may be suspected if a aortic stenosis or regurgitation (types of heart murmurs) murmur is found on physical examination. The diagnosis is confirmed by echocardiogram and/or heart catheterization demonstrating a flow pressure gradient below the aortic valve.

If left untreated subaortic stenosis results in an increased strain on the left ventricle (pumping chamber of the heart) and will lead to hypertrophy (enlargement of the heart). Ultimately this could lead to heart failure. Symptoms are shortness of breath, swelling in the legs, fatigue and difficulty lying flat.

Treatment is usually surgical. During surgery a portion of the muscle of the heart and the membrane are excised to relieve the obstruction. There are some reports of using percutaneous (non-surgical) balloon dilation of the membrane with success.

Recurrence of the obstruction can occur and may require repeat surgery. Follow-up usually consists of yearly echocardiograms. Medical treatment varies from case to case and depends on the condition of the heart muscle and associated medical problems.

Journal articles of interest that you can find at your local medical library are as follows:

Katz NM, et al. Discrete Membranous Subaortic Stenosis. Circulation. December 1977, Vol 56 No. 6 Pages 1034 - 1038.

Gewillig M, et. al. Rheologic Genesis of Discrete subvalvular Aortic Stenosis. Journal of the American College of Cardiology. March 15, 1992, Vol 19 No. 4 Pages 818 - 824.

Information provided here is for general educational purposes only. Only your doctor can provide specific diagnoses and treatments. If you would like to be seen at the Cleveland Clinic, please Call 1 - 800 - CCF - CARE for an appointment at Desk F15 with a cardiologist.