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01.12.2014 | Research article | Ausgabe 1/2014 Open Access

BMC Cardiovascular Disorders 1/2014

Contractile properties of the right atrial myofilaments in patients with myxomatous mitral valve degeneration

Zeitschrift:
BMC Cardiovascular Disorders > Ausgabe 1/2014
Autoren:
Constanze Bening, Uwe Mehlhorn, Lars Oliver Conzelmann, Nicole Stumpf, Anjuli Sikand, Christian-Friedrich Vahl
Wichtige Hinweise

Electronic supplementary material

The online version of this article (doi:10.​1186/​1471-2261-14-119) contains supplementary material, which is available to authorized users.

Competing interests

The authors declare that they have no competing interests.

Authors’ contributions

CB collected the tissue samples, performed the experiments, analyzed the results and wrote the manuscript. UM and LOC participated in the study design and proofread the manuscript. NS carried out the preparation of the solutions and collected the tissue samples. CV revised the manuscript. All authors read and approved the final manuscript.

Abstract

Background

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. 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.

Methods

Right 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.

Results

Patients 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).

Conclusions

Patients 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.
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