Mitral Valve Regurgitation - Cause
There are two forms of mitral valve regurgitation (MR): chronic and acute. Chronic mitral valve regurgitation develops slowly over several years. Acute MR develops suddenly.
Chronic mitral valve regurgitation
There are two types of chronic mitral valve regurgitation: primary and secondary.
Primary means there is a problem with the anatomy of the valve. The valve does not work well and does not close tightly.
Primary regurgitation can be caused by:
- Calcium buildup as a person ages. The mitral valve may become hard, or calcified, around the tough ring of tissue (annulus) to which the mitral valve flaps are attached. Normally the mitral annulus is soft and flexible. But as a person ages, calcium may build up inside the annulus. This hardened mitral valve cannot close completely, and blood leaks backward (regurgitates) into the upper left chamber of the heart (atrium).
- Mitral valve prolapse.
- Heart defects or abnormalities present at birth (congenital heart defects).
- Endocarditis, which is an infection of the lining of the heart and heart valves. This infection can scar the mitral valve.
- Autoimmune diseases that can damage the mitral valve, such as rheumatoid arthritis or lupus.
- Marfan's syndrome, which is a connective tissue disease.
- Rheumatic fever, which can scar the heart valves. This can prevent them from closing completely.
- Previous use of the weight-loss medicine fen-phen (phentermine and fenfluramine/dexfenfluramine), which appears to increase the risk of heart valve disease.
- Injury to the heart or the chordae tendineae, which are strong, flexible cords that control the opening and closing of the mitral valve.
Secondary means another heart problem is causing the valve to not close tightly. The anatomy of the valve is typically normal. The heart problem affects the heart muscle, and this causes regurgitation.
Secondary regurgitation can be caused by heart problems that affect the left ventricle. These problems include:
Acute mitral valve regurgitation
Acute mitral valve regurgitation occurs when the mitral valve or one of its supporting structures ruptures suddenly, creating an immediate overload of blood volume and pressure in the left side of the heart. Your heart doesn't have time to adjust to the increased volume and pressure of blood (as it does in chronic MR).
Causes of sudden rupture include:
- Injury to the chordae tendineae. Endocarditis may also cause the chordae tendineae to rupture.
- Injury to the chest.
- Heart attack, which may cause the rupture of the muscle (papillary) surrounding the valve.
- Problems with a prosthetic mitral valve.
- Perforation of the mitral valve flap (leaflet), caused by endocarditis.