title: The Geoform disease-specific annuloplasty system: a finite element study.
abstract: BACKGROUND
  Functional mitral regurgitation (FMR) is the inability of mitral leaflets to coapt due to a combination of functional and geometrical factors. Valve competence is commonly restored by undersized annuloplasty, reducing the native annulus anteroposterior dimension. In case of severe FMR, this solution may be inadequate. The use of rings specific for the correction of FMR may lead to better results.
  
  
  METHODS
  The performance of the Geoform ring, a recently designed FMR-specific prosthesis, was compared with that of a standard Physio annuloplasty ring. Finite element modeling was used to simulate dilated cardiomyopathy-related FMR and compare, at the systolic peak, the valve's pathologic condition with the postoperative scenario corresponding to both devices. Three degrees of the pathology were simulated by progressively displacing papillary muscles apically, up to 5 mm. Three ring sizes were modeled.
  
  
  RESULTS
  Regurgitant area, coaptation length, and stresses acting on valve structures were assessed. When the use of the Geoform was modeled, coaptation length was always longer than 7 mm. In the most unfavorable case, the regurgitant area reduction was 74% with respect to baseline, and leaflets stresses were reduced by 20% when undersizing was simulated. When Physio ring implantation was simulated, coaptation length maximum extent was equal to 4.3 mm, the maximum regurgitant area reduction was equal to 60%, and leaflet stress reduction was observed.
  
  
  CONCLUSIONS
  Disease-specific prostheses may allow for restoration of valve competence even for significant degrees of leaflets tethering and avoid the need for aggressive undersizing, thus leading to more durable results.
authors.affiliation: Politecnico di Milano, Bioengineering Department, Cardiac Surgery Division, IRCCS San Raffaele Hospital, Milan, Italy. emiliano.votta@polimi.it
authors.forename: Emiliano
authors.initials: E
authors.lastname: Votta
authors.forename: Francesco
authors.initials: F
authors.lastname: Maisano
authors.forename: Steven F
authors.initials: SF
authors.lastname: Bolling
authors.forename: Ottavio
authors.initials: O
authors.lastname: Alfieri
authors.forename: Franco M
authors.initials: FM
authors.lastname: Montevecchi
authors.forename: Alberto
authors.initials: A
authors.lastname: Redaelli
mesh_terms: D020342:Finite Element Analysis; D019918:Heart Valve Prosthesis Implantation / Q000379:methods*; D006801:Humans; D008943:Mitral Valve / Q000601:surgery*; D008944:Mitral Valve Insufficiency / Q000601:surgery*; D010210:Papillary Muscles / Q000601:surgery; D013314:Stress, Mechanical