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Case report: outer sheath rupture may precede complete chordal rupture in fibrotic mitral valve disease
K J Grande-Allen1, N B Ratliff, B P Griffin
1Department of Biomedical Engineering, Lerner Research Institute, The Cleveland Clinic Foundation, Ohio 44195, USA.
Abstract:
Rupture mechanics of mitral valve chordae have been difficult to elucidate because most surgical repairs and pathological examinations are performed after the rupture. In an excised anterior leaflet from a fibrotic mitral valve, chordae were observed in an initial phase of rupture. Microscopic sections showed that thinned, nearly ruptured chordal segments were actually chordal cores, containing highly aligned collagen fibers. The outer sheath of elastic fibers, disorganized circumferentially oriented collagen fibers, and endothelial cells that normally surrounds the collagen core apparently had retracted to the extreme ends of the thinned segment, resulting in a bulbous shape, as noted in the chordal rupture literature. In conclusion, these new observations lead us to propose that the rupture of mitral valve chordae is not spontaneous, but may occur over time. The failure of the outer sheath may represent the first phase in a slow, two-part process leading to eventual chordal rupture.
Insights
Mitral valve chordae rupture is a slow, two-part process. The outer sheath failure precedes the collagen core rupture, offering new insights into chordal failure mechanics.
Area of Science:
- Cardiovascular Biology
- Biomedical Engineering
- Pathology
Background:
- Understanding mitral valve chordae rupture mechanics is challenging due to examinations occurring post-rupture.
- Previous studies lacked detailed observation of the initial stages of chordal failure.
Observation:
- Examined an excised anterior mitral valve leaflet with chordae in an early rupture phase.
- Microscopic analysis revealed thinned chordal segments as exposed collagen cores with aligned fibers.
- Observed retraction of the outer sheath (elastic fibers, collagen, endothelium) to segment ends, creating a bulbous shape.
Findings:
- Mitral valve chordae rupture is not spontaneous but a gradual, time-dependent process.
- The initial phase involves the failure and retraction of the chordal outer sheath.
- The exposed collagen core is a key feature of early-stage chordal rupture.
Implications:
- This two-phase model provides a new perspective on mitral valve chordae rupture.
- Understanding this process may inform future surgical repair strategies for mitral valve disease.
- Further research into the biomechanics of sheath failure could prevent chordal rupture.