Abnormalities in elastic fibers and other connective-tissue components of floppy mitral valve

• Published in: The American heart journal Vol. 129; no. 6; pp. 1149 - 1158
• Main Authors: Tamura, Koichi, Fukuda, Yuh, Ishizaki, Masamichi, Masuda, Yukinari, Yamanaka, Nobuaki, Ferrans, Victor J.
• Format: Journal Article
• Language: English
• Published: New York, NY Mosby, Inc 01-06-1995; Elsevier
• Subjects: Actin Cytoskeleton - metabolism; Actin Cytoskeleton - ultrastructure; Adult; Aged; Aged, 80 and over; Biological and medical sciences; Cardiology. Vascular system; Chordae Tendineae - metabolism; Chordae Tendineae - pathology; Chordae Tendineae - ultrastructure; Collagen - metabolism; Connective Tissue - abnormalities; Connective Tissue - metabolism; Connective Tissue - pathology; Connective Tissue - ultrastructure; Cytoplasmic Granules - metabolism; Cytoplasmic Granules - ultrastructure; Dilatation, Pathologic - metabolism; Dilatation, Pathologic - pathology; Elastic Tissue - abnormalities; Elastic Tissue - metabolism; Elastic Tissue - pathology; Elastic Tissue - ultrastructure; Elastin - metabolism; Endocardial and cardiac valvular diseases; Endothelium - anatomy & histology; Endothelium - metabolism; Endothelium - ultrastructure; Female; Heart; Heart Valve Diseases - metabolism; Heart Valve Diseases - pathology; Humans; Immunohistochemistry; Male; Medical sciences; Microscopy, Electron; Middle Aged; Mitral Valve - anatomy & histology; Mitral Valve - metabolism; Mitral Valve - ultrastructure; Mitral Valve Prolapse - metabolism; Mitral Valve Prolapse - pathology; Proteoglycans - metabolism; Stress, Mechanical; Human; Prolapsus; Pathology; Connective tissue; Mitral valve; Cardiac valvular disease; Cardiovascular disease; Elastic fiber
• ISSN: 0002-8703; 1097-6744
• DOI: 10.1016/0002-8703(95)90397-6

Histologic, immunohistochemical, and ultrastructural studies were performed on 12 floppy mitral valves, 4 mitral valves showing focal myxomatous changes without prolapse, and 3 normal mitral valves. All floppy mitral valves were thickened by deposits of proteoglycans and also showed diverse structural abnormalities in collagen and elastic fibers. From these observations we conclude that (1) the structure of all major components of connective tissue in floppy mitral valves is abnormal; (2) alterations in collagen and accumulations of proteoglycans are nonspecific changes that may be caused by the abnormal mechanical forces to which floppy mitral valves are subjected because of their excessively large surface area; (3) the presence of excessive amounts of proteoglycans may interfere with the normal assembly of collagen and elastic fibers; (4) abnormalities of elastic fibers resemble those in other conditions characterized by structural dilatation or tissue expansion; and (5) alterations in elastin could result from defective formation, increased degradation, or both.