Functional mitral valve regurgitation occurs when the left atrium or left ventricle dilates, causing the mitral valve annulus to also dilate and prevent the mitral valve leaflets from properly coapting. There are many causes of left atrial and left ventricular dilation, and the treatment of this type of mitral regurgitation is directed at the primary cause. For example, if a patient develops systolic heart failure with a dilated left ventricle resulting in functional mitral regurgitation, treatment would be directed at the improvement of the heart failure.
The causes of mitral regurgitation are diverse since the mitral valve apparatus is complex. Mitral regurgitation can occur when the mitral valve apparatus is itself diseased (organic mitral regurgitation) or in the absence of any abnormality of the mitral valve apparatus (functional mitral regurgitation). The causes of functional and organic mitral regurgitation are listed in the table below.
Myxomatous changes (MVP)
Rheumatic heart disease (RHD)
Collagen vascular disease
Papillary muscle dysfunction
Mitral annular calcification (MAC)
Spontaneous chordal rupture
Left atrial dilation
Organic mitral regurgitation is caused by actual disease of the mitral valve apparatus. The mitral valve leaflets, annulus, papillary muscles and chordae tendinae must interact properly for the mitral valve to function properly. Thus, disruption of any of these structures can result in organic mitral regurgitation.