title: Rigid, complete annuloplasty rings increase anterior mitral leaflet strains in the normal beating ovine heart.
abstract: BACKGROUND
  Annuloplasty ring or band implantation during surgical mitral valve repair perturbs mitral annular dimensions, dynamics, and shape, which have been associated with changes in anterior mitral leaflet (AML) strain patterns and suboptimal long-term repair durability. We hypothesized that rigid rings with nonphysiological three-dimensional shapes, but not saddle-shaped rigid rings or flexible bands, increase AML strains.
  
  
  RESULTS
  Sheep had 23 radiopaque markers inserted: 7 along the anterior mitral annulus and 16 equally spaced on the AML. True-sized Cosgrove-Edwards flexible, partial band (n=12), rigid, complete St Jude Medical rigid saddle-shaped (n=12), Carpentier-Edwards Physio (n=12), Edwards IMR ETlogix (n=11), and Edwards GeoForm (n=12) annuloplasty rings were implanted in a releasable fashion. Under acute open-chest conditions, 4-dimensional marker coordinates were obtained using biplane videofluoroscopy along with hemodynamic parameters with the ring inserted and after release. Marker coordinates were triangulated, and the largest maximum principal AML strains were determined during isovolumetric relaxation. No relevant changes in hemodynamics occurred. Compared with the respective control state, strains increased significantly with rigid saddle-shaped annuloplasty ring, Carpentier-Edwards Physio, Edwards IMR ETlogix, and Edwards GeoForm (0.14 ± 0.05 versus 0.16 ± 0.05, P=0.024, 0.15 ± 0.03 versus 0.18 ± 0.04, P=0.020, 0.11 ± 0.05 versus 0.14 ± 0.05, P=0.042, and 0.13 ± 0.05 versus 0.16 ± 0.05, P=0.009), but not with Cosgrove-Edwards band (0.15 ± 0.05 versus 0.15 ± 0.04, P=0.973).
  
  
  CONCLUSIONS
  Regardless of three-dimensional shape, rigid, complete annuloplasty rings, but not a flexible, partial band, increased AML strains in the normal beating ovine heart. Clinical studies are needed to determine whether annuloplasty rings affect AML strains in patients, and, if so, whether ring-induced perturbations in leaflet strain states are linked to repair failure.
authors.affiliation: Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, CA 94305-5247, USA.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Bothe
authors.forename: Ellen
authors.initials: E
authors.lastname: Kuhl
authors.forename: John-Peder Escobar
authors.initials: JP
authors.lastname: Kvitting
authors.forename: Manuel K
authors.initials: MK
authors.lastname: Rausch
authors.forename: Serdar
authors.initials: S
authors.lastname: Göktepe
authors.forename: Julia C
authors.initials: JC
authors.lastname: Swanson
authors.forename: Saideh
authors.initials: S
authors.lastname: Farahmandnia
authors.forename: Neil B
authors.initials: NB
authors.lastname: Ingels
authors.forename: D Craig
authors.initials: DC
authors.lastname: Miller
mesh_terms: D000818:Animals; D006321:Heart / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006350:Heart Valve Prosthesis / Q000145:classification*; D006439:Hemodynamics / Q000502:physiology; D008297:Male; D008943:Mitral Valve / Q000502:physiology* / Q000601:surgery*; D058386:Mitral Valve Annuloplasty / Q000295:instrumentation* / Q000379:methods; D023421:Models, Animal; D011474:Prosthesis Design; D012756:Sheep; D016277:Ventricular Function, Left / Q000502:physiology