Thorac Cardiovasc Surg 2022; 70(S 02): S67-S103
DOI: 10.1055/s-0042-1743013
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Defined Structural Features Can Favor Infective Endocarditis in Bovine Jugular Vein Valved Conduits

K. Eildermann
1   Department of Paediatrics – Paediatric Cardiology, Intensive Care Medicine and Pneumology, Universitätsmedizin Göttingen, Göttingen, Deutschland
,
M. Sigler
1   Department of Paediatrics – Paediatric Cardiology, Intensive Care Medicine and Pneumology, Universitätsmedizin Göttingen, Göttingen, Deutschland
,
R. Scheidmann
2   Pädiatrische Pneumologie und Allergologie, Altona Children's Hospital, Hamburg, Deutschland
,
B. Ditkowski
3   Giga Cardiovascular, University of Liège, Liège, Belgium
,
R. Heying
4   Pediatric Cardiology, UZ Leuven, Leuven, Belgium
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Background: In 2017, first reports described an enhanced incidence of late-onset endocarditis in biological pulmonary valved conduits made from bovine jugular veins, as compared with valves from other sources. Since then, the mechanism behind this phenomenon has been a subject of much debate. The aim of this study was to compare cellular infiltration and extracellular matrix remodeling within homografts and bovine jugular vein valves in a sheep model.

Method: Homografts and bovine jugular vein valves were implanted in pulmonary position into sheep. After 4 months, valves were explanted, fixed in formalin, and prepared for histological analysis. The Movat–Verhoeff staining was applied to differentiate extracellular components; immunohistology was performed to detect lymphocytes, macrophages, granulocytes, contracting cells, fibroblasts, endothelial cells, and platelets.

Results: In homografts, there was a general reduction of cellular content, leading to thinning of the graft wall. Infiltration of recipient immune cells was detectable mainly in the adventitia and to some extent also in the leaflets. In bovine jugular vein valves, we saw significant infiltration with macrophages from the adventitial side. These cells displaced and thereby fragmented collagen fibers and formed foreign body giant cells. The bovine grafts thickened. However, no cellular infiltrations were detected within the valve leaflets. Spontaneous bacterial infections were observed in homografts and bovine jugular vein valves. As sheep were not treated with antibiotics, this enabled us to detect the locations of bacterial proliferation and the cellular reaction to the thread. While tightly packed collagen fibers prevented infiltration of immune cells, bacteria were small enough to enter and proliferate not being offended by the cellular immune system.

Conclusion: Homografts tissue contains living donor cells and a functional extracellular matrix that is accessible for enzymatic processing. In contrast, bovine jugular veins are treated with glutaraldehyde to reduce graft rejection. This procedure leads to the fixation of cells and to an enzymatically inaccessible extracellular matrix. The combination of glutaraldehyde fixation together with tightly packed collagen fibers in the leaflet of bovine jugular vein valves creates a shelter for bacterial proliferation, favoring infective endocarditis. This project was funded by the DGPK.



Publication History

Article published online:
12 February 2022

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