Mitral Valve Regurgitation often abbreviated as MR is a condition that occurs if the leaflets of a patient’s mitral valve do not seal or “coapt” properly when the left ventricle contracts allowing blood to flow backwards into the left atrium. The severity of MR is scored on a gradient from zero or none to 4+ or severe based on a multitude of factors including how much blood flows backwards when the heart beats. MR forces the heart to work harder to pump the same amount of oxygenated blood through the body. This causes the left ventricle to enlarge increasing the amount of mitral valve regurgitation and creating a vicious cycle that leads to pulmonary hypertension, symptomatic congestive heart failure, atrial fibrillation, right ventricular dysfunction and eventually death. 

 

Mitral valve regurgitation is generally divided into two categories: degenerative and functional. The majority of patients referred for surgery suffer from degenerative mitral valve disease.  Degenerative disease is caused by elongated or ruptured chordae tendineae that fail to support the mitral valve leaflets. When this happens, one or both leaflets prolapse backward into the left atrium and the valve does not close properly allowing blood to flow back into the left atrium when the heart beats (as illustrated in the animation below).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Functional mitral valve disease sometimes referred to as secondary, ischemic or idiopathic MR occurs when the left ventricle dilates. As the left ventrical and mitral valve annulus expand, the leaflets are no longer able to come together to close properly and blood flows backwards into the left atrium.