What Is Mitral Regurgitation (MR)? The mitral valve lies between the left atrium and the left ventricle. The valve’s two leaflike structures open when the atrium contracts, forcing blood from the left atrium into the left ventricle in only one direction. A healthy MV closes completely when the left ventricle contracts, preventing blood from leaking backward into the left atrium.

MR is the most common type of heart valve disease. It occurs when the mitral valve’s leaflets are not sealed tightly, and blood leaks backward from the left ventricle into the left atrium instead of flowing forward into the aorta.

MR affects the heart’s pumping efficiency, causing it to work harder to clear the regurgitated blood. MR can lead to congestive heart failure.

Current Treatment Options for MR. Over 4 million Americans suffer from MR. Depending on the severity of the symptoms, MR treatment ranges from medication to open heart surgery to repair or replace the valve. Due to their health state, some 1.6 million acute MR patients in the United States cannot undergo the open heart surgery required for treatment.