title: Contractile properties of the right atrial myofilaments in patients with myxomatous mitral valve degeneration.
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.
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, Medical Centre of the Johannes Gutenberg University Mainz, Langenbeckstr,1, 55131 Mainz, Germany. constanze.bening@googlemail.com.
authors.forename: Constanze
authors.initials: C
authors.lastname: Bening
authors.forename: Uwe
authors.initials: U
authors.lastname: Mehlhorn
authors.forename: Lars Oliver
authors.initials: LO
authors.lastname: Conzelmann
authors.forename: Nicole
authors.initials: N
authors.lastname: Stumpf
authors.forename: Anjuli
authors.initials: A
authors.lastname: Sikand
authors.forename: Christian-Friedrich
authors.initials: CF
authors.lastname: Vahl
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016280:Atrial Function, Right; D002118:Calcium / Q000378:metabolism; D005260:Female; D006325:Heart Atria / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D008944:Mitral Valve Insufficiency / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology* / Q000601:surgery; D008946:Mitral Valve Stenosis / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology* / Q000601:surgery; D053580:Muscle Strength; D009200:Myocardial Contraction; D009210:Myofibrils / Q000378:metabolism / Q000473:pathology; D018497:Ventricular Dysfunction, Right / Q000503:physiopathology; D016278:Ventricular Function, Right
chemical_list: D002118:Calcium