Is Inflammation the Culprit Mechanism in Mitral valve Prolapse?
Bastian Schneider, Johannes Holfeld, Cenk Özpeker, Can Tepeköylü, Michael Grabher, Günther Klima, Michael Grimm, Ludwig Müller.
Medical University of Innsbruck, Innsbruck, Austria.
OBJECTIVE: Mitral valve regurgitation due to a prolapse of leaflets is strongly associated with chordal rupture. Degeneration, inflammation or genetic pre-disposition are thought to be the underlying mechanism of action. However, knowledge on the etiology of mitral valve regurgitation is limited. This pilot study aims to elucidate the pathological process in order to achieve the ideal surgical strategy.
METHODS: We performed histopathological and immunhistochemical analysis of the chordae tendineae of 6 patients, who underwent mitral valve surgery due to mitral valve regurgitation. 2 samples of ruptured chordae, 2 samples of elongated fibrotic chordae and 2 samples of macroscopically normal secondary restrictive chordae were collected during cardiac surgery. Tissue was prepared in frozen sections and stained with hematoxylin eosin staining and electron microscope imaging. Immunofluorescence staining with DAPI and a cytokine profiler was performed to reveal a possible inflammatory process.
RESULTS: Hematoxylin eosin staining showed fibrotic thickening of elongated chordae and destruction of the chordal tissue of ruptured chordae. Electron micrograph imaging revealed desorganisation of collagen fibers in ruptured chordae. Levels of CD40, IL-23 und IFN-y inflammatory cytokines were significantly increased in ruptured chordae compared to healthy controls. Cell counting in DAPI staining showed cell infiltration in elongated chordae.
CONCLUSIONS: The detected increase of inflammatory cytokines in chordal tissue proves that an inflammatory process is present in chordal rupture. Cell infiltration in elongated non-ruptured chordae may give an indication for inflammation as a cause for chordal rupture. Further investigation will show, whether inflammation is the cause or the consequence of chordal rupture.
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