Mitral Valve Regurgitation: Cause

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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

The most common cause of chronic mitral valve regurgitation is mitral valve disease that damages the mitral valve flaps over time. The flaps then allow blood to leak backward (regurgitate) into the left atrium.

Other causes include:

• Hardening, or calcification, of 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, it is not uncommon for calcium to deposit inside the annulus. MR may occur when the calcified mitral valve cannot close completely and blood leaks backward into the left atrium.
• Heart defects or abnormalities present at birth (congenital).
• An infection of the lining of the heart and heart valves (endocarditis), which can cause scarring on the mitral valve.
• Injury to the heart or the chordae tendineae, which are strong, flexible cords that control the opening and closing of the mitral valve.
• Rheumatic fever, which can scar the heart valves and prevent them from closing completely.
• Previous use of the weight-loss medication Fen-Phen (phentermine and fenfluramine/dexfenfluramine), which appears to increase the risk of heart valve disease.
• Autoimmune diseases that can damage the mitral valves, such as rheumatoid arthritis, lupus, and Marfan's syndrome.
• Dilation of the left ventricle, or heart failure. This can be caused by years of high blood pressure, coronary artery disease, or heart muscle disease (cardiomyopathy).

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. Unlike in chronic MR, your heart doesn't have time to adjust to the increased volume and pressure of blood. Causes of the sudden rupture include:

• Injury to the chordae tendineae. This is most common in middle-aged and older men. 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.

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Last updated:	April 03, 2006
Author:	Cynthia Tank
Reviewed By:	Kathleen Romito, MD - Family Medicine, Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology
Editors:	Kathleen M. Ariss, MS, Terrina Vail