The cellular composition of explanted bioprosthetic heart valves in infective endocarditis

Mukhamadiyarov, R. А.; Rutkovskaya, N. V.; Milto, I. V.; Sidorova, O D; Ls, Barbarash

doi:10.17116/patol20198106116

Cited by 2 publications

(1 citation statement)

References 15 publications

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“…Появление гладких миоцитов в фибриновом слое может рассматриваться в качестве еще одного элемента адаптивной реакции. Кроме изоляции зон некроза они, возможно, берут на себя выполнение механической функции взамен разрушенного внеклеточного матрикса [11]. Обращает на себя внимание высокая жизнестойкость этих клеток в экстремальных условиях.…”

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Ultrastructural mitral valve abnormalities in infective endocarditis

Мухамадияров

Kutikhin

2021

Cardiovasc Ther Prev

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Aim. Using an original method based on backscattered scanning electron microscopy, to study the structural features of the mitral valve leaflets in infective endocarditis.Material and methods. We examined 9 mitral valves extracted during surgical interventions due to structural malfunction in patients with infective endocarditis (IE). The samples were fixed in buffered paraformaldehyde with osmium tetraoxide postfixation. After dehydration by increasing alcohol concentration and acetone, the samples were placed in epoxy resin. After the resin has polymerized, the samples were ground and then polished to the desired depth. To increase the electronic contrast, the samples were treated with a uranyl acetate alcohol solution during dehydration and with Reynolds' lead citrate after polishing the epoxy blocks. The samples were visualized by backscattered scanning electron microscopy at an accelerating 15-kV voltage.Results. Structural leaflet injuries caused by IE were most pronounced in the central part and the base. Necrotic areas were extensive electron-dense formations located in the central leaflet layers, or displaced towards the ventricular surface. The electron-dense material in the necrotic area was poorly structured and contained individual cells and bacteria. Bacteria were also present outside the necrotic area. Necrotic areas were surrounded by a layer of a modified extracellular matrix, usually covered with a fibrin layer. Among the extracellular matrix fibers, the macrophages, smooth myocytes and fibroblasts was noted. The fibrin layer, in addition to these cells, contained a large number of blood vessels and was often covered with endothelium.Conclusion. Infection of the mitral valve leaflets causes a simultaneous inflammatory response and regeneration activation. Without adequate regulatory factors, the processes of inflammation and connective tissue creation lead to structural and functional leaflet failure. Specific causes may be overgrowth of necrotic and inflammatory areas, edema and fiber orientation disorder, as well as leaflet rupture.

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Section: Discussionunclassified

Ultrastructural mitral valve abnormalities in infective endocarditis

Мухамадияров

Kutikhin

2021

Cardiovasc Ther Prev

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Ultrastructural pathology of bioprosthetic heart valves with infectious endocarditis

Mukhamadiyarov

Milto

Kutikhin

2021

Fundamentalʹnaâ i kliničeskaâ medicina

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Aim. To study the ultrastructure of mitral bioprosthetic heart valves (BHVs) which failed due to infective endocarditis.Materials and Methods. Here we examined 7 ethylene glycol diglycidyl ether-treated xenopericardial BHVs excised during repeated BHV replacement because of prosthetic endocarditis. After being fixed in formalin and postfixed in osmium tetroxide, BHVs were dehydrated and stained in uranyl acetate with the subsequent embedding into epoxy resin, grinding, polishing, and lead citrate counterstaining. Upon the sputter coating with carbon, we visualised the BHV microanatomy by means of backscattered scanning electron microscopy at 15 kV voltage.Results. The extracellular matrix underwent degradation and disintegration resulting in loosening, fragmentation, and reduction in the electron density of collagen and elastin fibers. We observed a number of recipient cells (macrophages, multinucleated giant cells, neutrophils, endothelial cells and smooth muscle cells) within the BHVs. The highest number of cells was localized on the valve surfaces. The localization of the recipient cells on the ventricular and atrial surfaces was different. The central part of the valves was abundantly populated by macrophages.Conclusion. Prosthetic endocarditis is accompanied by the migration of recipient cells into the BHV structure, which is the consequence of surface and extracellular matrix disintegration.

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The cellular composition of explanted bioprosthetic heart valves in infective endocarditis

Cited by 2 publications

References 15 publications

Ultrastructural mitral valve abnormalities in infective endocarditis

Ultrastructural mitral valve abnormalities in infective endocarditis

Ultrastructural pathology of bioprosthetic heart valves with infectious endocarditis

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