title: External approach to in vivo force measurement on mitral valve traction suture.
abstract: BACKGROUND
  Force measurements on the mitral valve apparatus have been reported from in vivo and in vitro studies. Recent reparative techniques for ischemic mitral valve insufficiency call for papillary muscle relocation. This study describes a device to measure forces generated on traction sutures utilized for this purpose.
  
  
  METHODS
  The transducer design was based on a modified caliper with strain gauges attached. Finite element computer simulation was employed to optimize the signal output. The system was designed to facilitate investigation of the effects of shortening GoreTex traction suture that was extended from near the fibrous trigones of the mitral valve through the papillary muscles. The suture was exteriorized out through the left ventricle in a porcine setup (n=11) and attached to the dedicated device for simultaneous papillary muscle relocation and traction suture force measurement.
  
  
  RESULTS
  The transducer demonstrated excellent signal strength, linearity, and durability. Peak force was seen at the onset of the systolic isovolumic contraction (p<0.001). Initial results indicated that this external approach can document force magnitudes comparable to previous internally measured forces in the mitral valve apparatus.
  
  
  CONCLUSIONS
  It has been proven feasible to measure forces in the mitral valve papillary muscle relocation sutures with an external device. The results from using this equipment will provide insight into the biomechanical requirements of relocation traction sutures and other devices utilized for papillary muscle relocation.
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, Institute of Clinical Medicine, Aarhus University Hospital, Skejby, Aarhus, Denmark. dr.morten.jensen@gmail.com
authors.forename: Morten O
authors.initials: MO
authors.lastname: Jensen
authors.forename: Henrik
authors.initials: H
authors.lastname: Jensen
authors.forename: Jesper Langhoff
authors.initials: JL
authors.lastname: Honge
authors.forename: Nygaard
authors.initials: N
authors.lastname: Hans
authors.forename: J Michael
authors.initials: JM
authors.lastname: Hasenkam
authors.forename: Sten L
authors.initials: SL
authors.lastname: Nielsen
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena / Q000502:physiology; D003198:Computer Simulation; D020342:Finite Element Analysis; D006352:Heart Ventricles / Q000503:physiopathology / Q000601:surgery; D008943:Mitral Valve / Q000502:physiology* / Q000601:surgery; D008944:Mitral Valve Insufficiency / Q000503:physiopathology* / Q000601:surgery; D008955:Models, Cardiovascular; D009200:Myocardial Contraction / Q000502:physiology*; D010210:Papillary Muscles / Q000502:physiology* / Q000601:surgery; D011138:Polytetrafluoroethylene / Q000627:therapeutic use; D013537:Sutures; D013552:Swine; D013599:Systole / Q000502:physiology; D014143:Traction / Q000379:methods
chemical_list: D011138:Polytetrafluoroethylene