title: Is a cleft in the anterior leaflet of an otherwise normal mitral valve an atrioventricular canal malformation?
abstract: OBJECTIVE
  This study sought to ascertain the surgical anatomy of a cleft in the left atrioventricular (AV) valve.
  
  
  BACKGROUND
  Important morphologic differences exist between hearts with a cleft in the anterior leaflet of an otherwise normal mitral valve and those with a so-called cleft in the left AV valve when there is an AV septal defect, but it has been customary to link the lesions together on developmental grounds.
  
  
  METHODS
  Eight autopsied specimens with a cleft in the aortic (or anterior) leaflet of the mitral valve were studied in detail, and echocardiograms from 21 patients with such a cleft were compared with the specimens and with findings typical of the so-called partial AV canal and other forms of AV septal defect.
  
  
  RESULTS
  The structure and direction of the cleft, location of the papillary muscles within the left ventricle and AV junctional morphology of hearts with an otherwise normally structured mitral valve were significantly different from typical findings in hearts with AV septal defects.
  
  
  CONCLUSIONS
  It is necessary to distinguish morphologically a cleft in an otherwise normally structured mitral valve in hearts with separate right and left AV junctions from the trifoliate left component of a common AV valve in hearts with an AV septal defect and a common AV junction because the disposition of the AV conduction tissues varies markedly between the lesions.
authors.affiliation: Division of Cardiology, Children's Hospital of Pittsburgh, Pennsylvania, USA.
authors.forename: G
authors.initials: G
authors.lastname: Sigfússon
authors.forename: J A
authors.initials: JA
authors.lastname: Ettedgui
authors.forename: N H
authors.initials: NH
authors.lastname: Silverman
authors.forename: R H
authors.initials: RH
authors.lastname: Anderson
mesh_terms: D001344:Autopsy; D002648:Child; D002675:Child, Preschool; D004452:Echocardiography; D004694:Endocardial Cushion Defects / Q000196:embryology*; D006801:Humans; D008943:Mitral Valve / Q000002:abnormalities* / Q000000981:diagnostic imaging; D012720:Severity of Illness Index