Evidence of woven bone formation in heart valve disease

The pathogenesis of acquired cardiac valve disease still remains a matter of controversy. In this work, scanning electron and polarised light microscopic investigations in addition to energy dispersive X-ray microanalyses (EDAX) were carried out on explanted human aortic and mitral valves to determine the morphology and element composition of calcified areas in valvular lesions. Biopsies were taken from aortic valves removed from 28 male patients (average age, 75+/-1 years) and 46 females (68+/-3 years) and from mitral valves obtained from 18 male patients (72+/-3 years) and 8 females (71+/-6 years). By means of scanning electron microscopy, multiple foci of calcified areas were identified. Endothelial cells in these areas appeared swollen and displayed reduced cell-cell contacts. The calcium deposits were separated from the adjacent tissue by layers of collagen fibers. Often a layer of woven bone tissue separated intravalvular inclusions from hyperplastic collagen fibers. Using EDAX analysis, calcium and phosphorus were detected in these valvular lesions. The major finding of our study is the presence of woven bone tissue in explanted cardiac valves, which may result from pathological strains or mechanical overloading of the collagen fibers.