title: Geometric distortions of the mitral valvular-ventricular complex in chronic ischemic mitral regurgitation.
abstract: BACKGROUND
  Better understanding of the precise 3-dimensional geometric changes of the mitral valvular-ventricular complex in chronic ischemic mitral regurgitation (CIMR) is needed in order to devise better surgical repair techniques. We hypothesized that changes after inferior myocardial infarction would be different in hearts that developed CIMR compared with those that did not.
  
  
  RESULTS
  Twenty-four sheep underwent coronary snare and marker placement (annulus, papillary muscles, and anterior and posterior leaflets). After 8 days, cinefluoroscopy provided 3-dimensional marker data, and snare occlusion of obtuse marginal branches created inferior myocardial infarction, including the posterior papillary muscle. After 7 weeks, the 16 surviving animals were studied again and grouped by mitral regurgitation grade (>or= 2+, n=10 versus <or= 1+, n=6). End-systolic mitral annulus dimensions, components of papillary muscle and leaflet displacement, were calculated. After inferior myocardial infarction, total displacement of the posterior papillary muscle from the midseptal annulus ("saddle horn") was greater in CIMR(+) animals: 6.5+/-3.2 versus 3.1+/-2.7 (P=0.02), with the posterior papillary muscle moving more laterally (6.8+/-3.4 versus 2.5+/-3.5 mm, P=0.01). Increase in mitral annular septal-lateral diameter was greater in animals with CIMR (4.9+/-2.7 versus 2.3+/-2.0, P=0.02), and apical displacement of the posterior leaflet (PL) margin was also greater in the CIMR(+) group (1.7+/-1.0 versus 0.3+/-0.5, P=0.01).
  
  
  CONCLUSIONS
  The CIMR(+) group had greater septal-lateral annular dilatation, lateral posterior papillary muscle displacement, and apical PL restriction, indicating that these associated geometric alterations may be important in the pathogenesis of CIMR. Treatment of CIMR should address both annular septal-lateral dilatation and lateral displacement of the posterior papillary muscle.
authors.affiliation: Department of Cardiovascular and Thoracic Surgery, Stanford University School of Medicine, Stanford, CA 94305-5247, USA.
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Tibayan
authors.forename: Filiberto
authors.initials: F
authors.lastname: Rodriguez
authors.forename: Mary K
authors.initials: MK
authors.lastname: Zasio
authors.forename: Lynn
authors.initials: L
authors.lastname: Bailey
authors.forename: David
authors.initials: D
authors.lastname: Liang
authors.forename: George T
authors.initials: GT
authors.lastname: Daughters
authors.forename: Frank
authors.initials: F
authors.lastname: Langer
authors.forename: Neil B
authors.initials: NB
authors.lastname: Ingels
authors.forename: D Craig
authors.initials: DC
authors.lastname: Miller
mesh_terms: D000818:Animals; D002908:Chronic Disease; D006352:Heart Ventricles / Q000473:pathology*; D006439:Hemodynamics; D008943:Mitral Valve / Q000473:pathology*; D008944:Mitral Valve Insufficiency / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D009203:Myocardial Infarction / Q000150:complications; D010210:Papillary Muscles / Q000473:pathology; D012756:Sheep