title: Edge-to-edge mitral repair: tension on the approximating suture and leaflet deformation during acute ischemic mitral regurgitation in the ovine heart.
abstract: BACKGROUND
  Edge-to-edge approximation of the mitral valve leaflets (Alfieri procedure) is a novel surgical treatment for patients with ischemic mitral regurgitation (IMR). Long-term durability may be limited if abnormal mitral leaflet stresses result from this procedure. The aim of the current study was to measure Alfieri stitch tension (F(A)) and to explore its geometric determinants in an ovine model of acute IMR as a reflection of the mitral leaflet stresses imposed by the procedure.
  
  
  RESULTS
  Eight sheep were studied immediately after surgical placement of (1) a force transducer interposed between sutures approximating the central leaflet edges and (2) radiopaque markers around the mitral annulus and leaflet edges. Computer-aided analysis of videofluorograms was used to obtained 3D marker coordinates. Simultaneous measurements of F(A), septal-lateral annular dimension (L(S-L)), leaflet edge separation (L(SEP)), anterior (L(AL)) and posterior (L(PL)) leaflet length, and hemodynamic variables were obtained at baseline (CTL) and during acute IMR (circumflex artery occlusion). F(A) was significantly elevated throughout the cardiac cycle during IMR compared with CTL, with maximum F(A) in diastole (0.26+/-0.05 versus 0.46+/-0.08 N, CTL versus IMR; P<0.05). Multivariable analysis revealed L(S-L) as the single independent predictor of maximum F(A) (P<0.001). Positive linear correlations were shown between values of F(A) and L(AL) and L(PL) (dependent variables).
  
  
  CONCLUSIONS
  These experimental data demonstrate higher F(A) during IMR and cyclic changes in F(A) closely paralleling changes in L(S-L), eg, being greatest in diastole when the annulus is largest. Increased F(A) during IMR is probably indicative of successful therapeutic intent, but higher diastolic leaflet stresses resulting from persistent or progressive mitral annular dilatation may adversely affect repair durability. This indirectly implies that concomitant mitral ring annuloplasty should be added to the Alfieri repair.
authors.affiliation: Department of Cardiothoracic Surgery, Institute of Experimental Clinical Research, Aarhus University Hospital-Skejby Sygehus, Aarhus, Denmark. dcm@stanford.edu
authors.forename: S L
authors.initials: SL
authors.lastname: Nielsen
authors.forename: T A
authors.initials: TA
authors.lastname: Timek
authors.forename: D T
authors.initials: DT
authors.lastname: Lai
authors.forename: G T
authors.initials: GT
authors.lastname: Daughters
authors.forename: D
authors.initials: D
authors.lastname: Liang
authors.forename: J M
authors.initials: JM
authors.lastname: Hasenkam
authors.forename: N B
authors.initials: NB
authors.lastname: Ingels
authors.forename: D C
authors.initials: DC
authors.lastname: Miller
mesh_terms: D000208:Acute Disease; D000818:Animals; D006348:Cardiac Surgical Procedures; D003971:Diastole; D004195:Disease Models, Animal; D015150:Echocardiography, Doppler; D018618:Echocardiography, Doppler, Color; D005471:Fluoroscopy / Q000379:methods; D006439:Hemodynamics; D008943:Mitral Valve / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D008944:Mitral Valve Insufficiency / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D015999:Multivariate Analysis; D017202:Myocardial Ischemia / Q000150:complications; D012756:Sheep; D013314:Stress, Mechanical; D013536:Suture Techniques; D013599:Systole