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Detailed examination of complete bioprosthetic heart valves
J Butany1, G d'Amati, V Fornasier
1Department of Pathology, Toronto Hospital (TGH Division), Ontario, Canada.
Insights
Histological examination of explanted bioprosthetic valves revealed significant pannus deposition and cellular infiltration. Degeneration and calcification were noted, alongside changes in non-biologic components, potentially impacting function.
Area of Science:
- Cardiovascular research
- Biomaterials science
- Histopathology
Background:
- Bioprosthetic heart valves (BHVs) are widely used but can undergo structural degeneration.
- Understanding the long-term histological changes in explanted BHVs is crucial for improving valve design and patient outcomes.
Purpose of the Study:
- To perform a detailed histological analysis of explanted bioprosthetic heart valves.
- To identify and characterize tissue ingrowth, cellular infiltration, and material degradation in explanted BHVs.
Main Methods:
- Histological examination of six bioprostheses (three control, three explanted) using embedding and sectioning techniques.
- Analysis focused on cusp changes, pannus formation, cellular infiltration, and degradation of both biologic and non-biologic components.
Main Results:
- Extensive pannus deposition on inflow surfaces and biologic components was observed.
- Evidence of tissue fluid insudation, fibroblast ingrowth, collagen deposition, and mononuclear cell infiltration was found.
- Degradation and cellular changes were also noted in the non-biologic components, including synthetic covering, plastic, and metal.
Conclusions:
- Explanted bioprosthetic valves exhibit significant tissue ingrowth and cellular infiltration beyond previously reported cusp degeneration.
- Degradation of non-biologic components may contribute to impaired prosthesis function.
- Further studies with a larger sample size are needed to draw definitive conclusions.
Abstract:
Six (3 control and 3 explanted) bioprostheses were examined histologically after embedding the complete valve in "plastic" and sectioning across the valve at 90 degree to the horizontal plane, and then horizontally across a stent post, with a low speed saw. The prostheses, porcine or pericardial, had been in place 52 to 121 months. In addition to cusp changes of degeneration and calcification that have been previously reported, the authors found extensive pannus deposition on the cloth covering the inflow surface of the prostheses, with some extension onto the biologic components; evidence of insudation of tissue fluid and ingrowth of fibroblasts; deposition of collagen; and infiltration of mononuclear cells in the interstices and interfaces. Non-biologic components showed changes which may have affected prosthesis function. The synthetic material covering the metal/plastic frame showed interstitial mononuclear cells. Two of the three explanted valves showed changes in the polymeric plastic, and one in the metal components, including accentuated notching along the surfaces when compared to unimplanted prostheses. A larger number of prostheses must be examined before definite conclusions can be drawn.