A comparative analysis of mitral valve changes in different age groups by histochemical, immunohistochemical and ultrastructural study

Introduction Mitral valve prolapse (MVP) is an increasingly prevalent clinical problem posing a surgical and diagnostic challenge for cardiac surgeons and cardiologists respectively. The commonest MVP etiologies are age-related degenerative (60%), rheumatic (12%) and functional (25%). The age related changes in valve can be collagen and elastic fiber disruption, calcification and mucopolysaccharides (MPS) accumulation. Methods Tissues from 60 formalin fixed human hearts were taken for histomorphology and immunohistochemistry and for ultrastructural analysis in 15 of them. Results Among 60 mitral valves, mild fibrosis was present in 4 cases (40%) in 2nd decade, 8 cases (80%) in 3rd decade, 4 cases (40%) in 4th and 5th decades, and 6 cases (6%) in 6th decade and only 1 case (10%) in 7th decade. Majority of the mitral valves (90%) in 7th decade showed moderate fibrosis. The MPS material deposition was mild in 60%, 20% and 10% cases in 2nd, 3rd and 5th decades respectively whereas it was moderate to severe in 4th to 5th decades. Immunohistochemistry showed moderate and severe decorin positivity in 18/60 (30%) and 1/60 (1.66%) cases respectively whereas mild and moderate biglycan positivity was seen in 34/60 (56.66%) and 8/60 (13.33%) cases respectively. Ultrastructurally, collagen fibers were fragmented with numerous inclusions of MPS material, and fibroblasts with increasing age. Discussion The present study highlighted that fibrosis and MPS accumulation in MV leaflets increases with advancing age along with the increased expression of decorin and biglycan.