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Cuspal dehiscence at a post and along the stent cloth in a bovine pericardium heart valve implanted for seven years
Robert Guidoin1, Taniela Marli Bes, Tomas Francisco Cianciulli
1Department of Surgery and Radiology, Laval University, Quebec, Canada. robertguidoin@hotmail.com
Insights
Structural failure of a bovine pericardium mitral valve prosthesis led to severe regurgitation. Examination revealed cusp dehiscence and impaired function due to pannus overgrowth, without calcification.
Area of Science:
- Biomaterials Science
- Cardiovascular Surgery
- Pathology
Background:
- Bovine pericardium is widely used for heart valve prostheses.
- Structural failure can lead to severe mitral regurgitation.
- Understanding failure mechanisms is crucial for improving valve design.
Purpose of the Study:
- To investigate the failure mechanism of a degenerated bovine pericardium mitral valve prosthesis.
- To characterize structural changes in the pericardium after 7 years of implantation.
Main Methods:
- Explantation of a failing mitral valve prosthesis.
- Macroscopic, scanning electron microscopy (SEM), light microscopy, and transmission electron microscopy (TEM) analysis.
- Comparison with pre-implantation control bovine pericardium tissue.
Main Results:
- Complete dehiscence of a cusp from the valve post and stent was observed.
- Significant fibrous pannus overgrowth adhered poorly and stiffened the valve cusps.
- Pericardium cusp structure showed deteriorated collagen bundles, lacking normal wavy patterns.
- No evidence of calcification was found in the explanted device.
Conclusions:
- The primary failure mode was cusp dehiscence due to structural deterioration and pannus overgrowth, not calcification.
- Degradation of collagen structure in bovine pericardium compromises valve integrity over time.
- Findings highlight the need for improved biomaterials and designs to enhance durability of pericardial heart valves.
Abstract:
A failing mitral valve prosthesis made from bovine pericardium was explanted from a 50-year-old patient. Preoperative transthoracic-echocardiography had confirmed severe mitral regurgitation due to structural failure of this HP Bio bovine pericardium heart valve prosthesis. The explanted device was examined macroscopically, by scanning electron microscopy (SEM), by light microscopy, and by transmission electron microscopy (TEM). Samples of unassembled patches of bovine pericardium were used as a pre-implantation control to better understand the changes that occurred in the structure of the pericardium following the 7 years of implantation. Examination confirmed complete dehiscence of a cusp along a valve post and the stent: This detached cusp was observed floating in the bloodstream at echocardiography. The fibrous pannus overgrowth was well developed along the stent and extended to the bottom of the cusps both on the inflow and the outflow sides. The fibrous panni were found to be poorly adhesive to the pericardium cusps and had become stiff, thus impairing the opening and closure of the valve. The structure of the pericardium cusps was severely deteriorated compared to the control bovine pericardium tissue samples. The collagen bundles were frequently broken and more stretched in the explanted device, lacking the wavy histological pattern of normal collagen fibers. However, the tissues were devoid of any calcification. In conclusion, the failure mode of this valve was the dehiscence of a cusp from a valve post and along the stent cloth in the absence calcification.
