title: Mitral valve mechanics following posterior leaflet patch augmentation.
abstract: OBJECTIVE
  Attention towards the optimization of mitral valve repair methods is increasing. Patch augmentation is one strategy used to treat functional ischemic mitral regurgitation (FIMR). The study aim was to investigate the force balance changes in specific chordae tendineae emanating from the posterior papillary muscle in a FIMR-simulated valve, following posterior leaflet patch augmentation.
  
  
  METHODS
  Mitral valves were obtained from 12 pigs (body weight 80 kg). An in vitro test set-up simulating the left ventricle was used to hold the valves. The left ventricular pressure was regulated with water to simulate different static pressures during valve closure. A standardized oval pericardial patch (17 x 29 mm) was introduced into the posterior leaflet from mid P2 to the end of the P3 scallop. Dedicated miniature transducers were used to record the forces exerted on the chordae tendineae. Data were acquired before and after 12 mm posterior and 5 mm apical posterior papillary muscle displacement to simulate the effect from one of the main contributors of FIMR, before and after patch augmentation.
  
  
  RESULTS
  The effect of displacing the posterior papillary muscle induced tethering on the intermediate chordae tendineae to the posterior leaflet, and resulted in a 39.8% force increase (p = 0.014). Posterior leaflet patch augmentation of the FIMR valve induced a 31.1% force decrease (p = 0.007). There was no difference in force between the healthy and the repaired valve simulations (p = 0.773).
  
  
  CONCLUSIONS
  Posterior leaflet patch augmentation significantly reduced the forces exerted on the intermediate chordae tendineae from the posterior papillary muscle following FIMR simulation. As changes in chordal tension lead to a redistribution of the total stress exerted on the valve, patch augmentation may have an adverse long-term influence on mitral valve function and remodeling.
authors.affiliation: Department of Engineering, University of Aarhus, Aarhus, Denmark.
authors.forename: Azadeh
authors.initials: A
authors.lastname: Rahmani
authors.forename: Ann Q
authors.initials: AQ
authors.lastname: Rasmussen
authors.forename: Jesper L
authors.initials: JL
authors.lastname: Honge
authors.forename: Bjorn
authors.initials: B
authors.lastname: Ostli
authors.forename: Robert A
authors.initials: RA
authors.lastname: Levine
authors.forename: Albert
authors.initials: A
authors.lastname: Hagège
authors.forename: Hans
authors.initials: H
authors.lastname: Nygaard
authors.forename: Sten L
authors.initials: SL
authors.lastname: Nielsen
authors.forename: Morten O
authors.initials: MO
authors.lastname: Jensen
mesh_terms: D000818:Animals; D002815:Chordae Tendineae / Q000502:physiology; D008943:Mitral Valve / Q000502:physiology / Q000601:surgery*; D008944:Mitral Valve Insufficiency / Q000601:surgery*; D010210:Papillary Muscles / Q000502:physiology / Q000601:surgery*; D013552:Swine