Anatomic and functional features of the normal and abnormal mitral valve are reviewed.
Of 1,010 personally studied necropsy patients with severe (functional class III or
IV, New York Heart Association) cardiac dysfunction from primary valvular heart disease,
434 (43%) had mitral stenosis (MS) with or without mitral regurgitation (MR): unassociated
with aortic valve stenosis or regurgitation or with tricuspid valve stenosis in 189
(44%) patients, and associated with aortic stenosis in 152 (35%), with pure (no element
of stenosis) aortic regurgitation in 65 (15%) patients, and with tricuspid valve stenosis
with or without aortic valve stenosis in 28 (6%) patients. The origin of MS was rheumatic
in all 434 patients. Of the 1,010 necropsy patients, 165 (16%) had pure MR (papillary
muscle dysfunction excluded): unassociated with aortic valve stenosis or regurgitation
or with tricuspid valve stenosis in 97 (59%) patients, and associated with pure aortic
regurgitation in 45 (27%) and with aortic valve stenosis in 23 (14%) patients. When
associated with dysfunction of the aortic valve, pure MR was usually rheumatic in
origin, but when unassociated with aortic valve dysfunction it was usually nonrheumatic
in origin. Review of operatively excised mitral valves in patients with pure MR unassociated
with aortic valve dysfunction disclosed mitral valve prolapse (most likely an inherent
congenital defect) as the most common cause of MR. Excluding the patients with MR
from coronary heart disease (papillary muscle dysfunction), mitral prolapse was the
cause of MR in 60 (88%) of the other 68 patients, and a rheumatic origin was responsible
in only 3 of the 68 patients, all 68 of whom were greater than 30 years of age. Mitral
anular calcification in persons aged greater than 65 years is usually associated with
calcific deposits in the aortic valve cusps and in the coronary arteries. Because
calcium in each of these 3 sites is common in older individuals residing in the Western
World, it is most reasonable to view mitral anular calcification in older individuals
as a manifestation of atherosclerosis. Mitral anular calcium appears to be extremely
uncommon in persons with total serum cholesterol levels less than 150 mg/dl. Mitral
anular calcium may produce mild MR and, if the deposits are heavy enough, MS.