Ultrastructural changes of cardiac valves in bacterial endocarditis

The principal objective of this study was to document morphological changes in valves with acute endocarditis in order to gain further knowledge of the pathogenesis of these diseases.

Scanning and transmission electron microscopic investigations were carried out on explanted human heart valves to reveal ultrastructural changes due to bacterial endocarditis.

Bacterial inflammation endocarditis initially induced metaplasia of the endothelial cells which then lose contact with each other. In the 2nd phase of the disease, the collagen fibres are systematically removed whereby large cavities appear. In the 3rd phase, localised hyperplasia of collagen fibres was observed often resulting in the development of vegetation. The ultrastructural changes are uniform and independent of the bacterial species.

Bacterial endocarditis is therefore a set of complex interactions between endothelial cells and bacteria which should be taken into consideration for the development of new therapeutic approaches.