Abstract
BackgroundMyxomatous degeneration of the mitral valve is a common pathological finding in mitral valve surgery and the most common reason for severe mitral valve regurgitation. Considering the importance of right ventricular remodeling and global function after mitral valve surgery we tried to elucidate a possible association of myxomatous mitral valve and impairment of right atrial and ventricular function, which might have an impact on global ventricular performance after mitral valve surgery.MethodsRight atrial tissue was harvested from 47 patients undergoing mitral valve surgery. We took the trabeculae from the right auricle, which was resected at the right auricle for implementation of extracorporal circulation. The tissue was skinned and prepared in a 24 h-lasting procedure to create small fibers for hinging them in the "muscle machine", an experimental set-up, created for pCa-force measurements.ResultsPatients without myxomatous mitral valve developed significantly more force (4.0 mN ± 0.8 mN) at the highest step of calcium concentration compared to 2.7 mN ± 0.4 mN in group of patients with myxomatous valve degeneration (p 0.03). Calcium sensitivity in the myxomatous valve group was at pCa 6.0 and in the non-myxomatous group at pCa 5. Furthermore we observed a significant difference in ejection fraction (EF) among the groups: 49% in the non-myxomatous group versus 57% in the myxomatous group (p 0.03). In the non-myxomatous group 5 patients had diastolic dysfunction grade I-II (22,7%), in group I 10 patients (40%). This was also significant (p 0.04).ConclusionsPatients with myxomatous mitral valve degeneration seem to have reduced force capacities. Calcium sensitivity is higher compared to the non-myxomatous group, which might be a compensatory mechanism to cover the physiological demand. Furthermore we suggest a higher incidence of diastolic dysfunction in patients with myxomatous mitral valve degeneration, which might have an impact on ventricular remodeling after mitral valve surgery.
Highlights
Myxomatous degeneration of the mitral valve is a common pathological finding in mitral valve surgery and the most common reason for severe mitral valve regurgitation
The assumption of being a sign of ageing comes from examinations with canines: a wide range of examinations were performed in dogs, because the myxomatous mitral valve degeneration (MMVD) is the most common cardiac disease in dogs and there are strong evidences for a close dependency of age and this disease [6]
Comparing the clinical features we observed in these two groups, we find some noticeable results: We observe a significant difference in ejection fraction (EF) among the groups: 49% in the non-myxomatous group versus 57% in the myxomatous group (p 0.03)
Summary
Myxomatous degeneration of the mitral valve is a common pathological finding in mitral valve surgery and the most common reason for severe mitral valve regurgitation. Chordae are longer and leaflets are enlarged, failing deficiency syndrome and other connective tissue disorders but can be found in the elderly [5] which might allow the assumption of MMVD to be a symptom of ageing of the valve. This finding is not new: The first description of myxomatous mitral valves can already be found in 1910 (Dewitzky, Felsenreich and von Weisner 1915). Some analogies absolutely exist between humans and dogs [7]
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