title: Evidence of a vicious cycle in mitral regurgitation with prolapse: secondary tethering attributed to primary prolapse demonstrated by three-dimensional echocardiography exacerbates regurgitation.
abstract: BACKGROUND
  In patients with mitral valve prolapse, nonprolapsed leaflets are often apically tented. We hypothesized that secondary left ventricular dilatation attributed to primary mitral regurgitation (MR) causes papillary muscle (PM) displacement, resulting in this leaflet tenting/tethering, and that secondary tethering further exacerbates malcoaptation and contributes to MR severity.
  
  
  RESULTS
  Three-dimensional transesophageal echocardiography was performed in 25 patients with posterior mitral leaflet prolapse with an intact anterior mitral leaflet (AML) and 20 controls. From 3D zoom data sets, 11 equidistant antero-posterior cut planes of the mitral valve at midsystole were obtained. In each plane, tenting area of nonprolapsed leaflet and prolapse area of prolapsed leaflet were measured. Prolapse/tenting volume of each region was obtained as the product of interslice distance and the prolapse/tenting area. AML tenting volume and whole leaflet prolapse/tenting volume were then obtained. The PM tethering distance between PM tips and anterior mitral annulus was measured from 3D full-volume data sets. The severity of MR was quantified by vena contracta area extracted from color 3D transesophageal echocardiography data sets. AML tenting volume was significantly larger in patients with posterior mitral leaflet prolapse compared with that in controls (1.2 ± 0.5 versus 0.6 ± 0.2 mL/m(2); P<0.001). Multivariate regression analysis identified independent contribution to AML tenting volume from an increase in PM tethering distance. Multivariate regression analysis identified independent contributions to MR severity (vena contracta area) from both whole leaflet tenting volume (r=0.44; P<0.05) and prolapse volume (r=0.44; P<0.05). AML tenting volume decreased along with left ventricular volume and PM tethering distance postrepair (n=8; P<0.01).
  
  
  CONCLUSIONS
  These results suggest that primary mitral valve prolapse with MR causes secondary mitral leaflet tethering with PM displacement by left ventricular dilatation, which further exacerbates valve leakage, constituting a vicious cycle that would suggest a pathophysiologic rationale for early surgical repair.
authors.affiliation: Second Department of Internal Medicine, University of Occupational and Environmental Health, School of Medicine, Kitakyushu, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Otani
authors.forename: Masaaki
authors.initials: M
authors.lastname: Takeuchi
authors.forename: Kyoko
authors.initials: K
authors.lastname: Kaku
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Haruki
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Yoshitani
authors.forename: Masataka
authors.initials: M
authors.lastname: Eto
authors.forename: Masahito
authors.initials: M
authors.lastname: Tamura
authors.forename: Masahiro
authors.initials: M
authors.lastname: Okazaki
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Abe
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Fujino
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Nishimura
authors.forename: Robert A
authors.initials: RA
authors.lastname: Levine
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Otsuji
mesh_terms: D000368:Aged; D000886:Anthropometry; D004108:Dilatation, Pathologic / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D018450:Disease Progression; D019560:Echocardiography, Three-Dimensional; D017548:Echocardiography, Transesophageal; D005260:Female; D006352:Heart Ventricles / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000000981:diagnostic imaging*; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008945:Mitral Valve Prolapse / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology; D008955:Models, Cardiovascular; D009038:Motion; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology