title: Annulus fibrosus of the mitral valve: reality or myth.
abstract: BACKGROUND
  Surgical repair of the mitral valve is in most cases limited to the posterior leaflet of the mitral valve and to the annulus fibrosus. The term annulus fibrosus is still used in anatomical and clinical terminology and is described as a cord like structure providing the attachment of the mitral vale. However, to date no evidence exists of a ring-or cord-like structure at this area. Herein, we describe the attachment of the mitral valve by using the macroscopical and microscopical techniques.
  
  
  METHODS
  The ventricular attachment of the posterior mitral valve leaflet was investigated in 10 human hearts. In dry dissected specimens, the intraventricular illumination was used to identify the attachment of the mitral valve to the left ventricular muscle. Using the histological techniques, we verified the position of the annulus fibrosus.
  
  
  RESULTS
  The attachment of the posterior mitral valve leaflet is a band-like structure positioned between the left ventricular muscle and the left atrium. This fibrous band illustrates the morphological attachment of the mitral valve and, as thus, was interpreted as the annulus fibrosus of the mitral valve.
  
  
  CONCLUSIONS
  Based on our data, no ring-like structure was found corresponding to the anatomical description of the annulus fibrosus, instead the band-like fibrous tissue was identified positioned between the mitral valve and the left ventricle. Histologicaly, we detected that this structure is part of the greater structural system that is directly connected to the membranous septum, to the left and right fibrous trigone and the attachment aortic root to the left ventricular muscle.
authors.affiliation: University Hospital Zürich, Department of Cardiovascular Surgery, Rämistrasse, Zürich, Switzerland. denis.berdajs@usz.ch
authors.forename: Denis
authors.initials: D
authors.lastname: Berdajs
authors.forename: Gregor
authors.initials: G
authors.lastname: Zünd
authors.forename: Colette
authors.initials: C
authors.lastname: Camenisch
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schurr
authors.forename: Marko I
authors.initials: MI
authors.lastname: Turina
authors.forename: Michele
authors.initials: M
authors.lastname: Genoni
mesh_terms: D000328:Adult; D000368:Aged; D002102:Cadaver; D016326:Extracellular Matrix Proteins; D006349:Heart Valve Diseases; D006801:Humans; D008875:Middle Aged; D008943:Mitral Valve / Q000033:anatomy & histology* / Q000473:pathology; D010865:Pilot Projects