title: Coordinate-free analysis of mitral valve dynamics in normal and ischemic hearts.
abstract: BACKGROUND
  The purpose of this investigation was to study mitral valve 3D geometry and dynamics by using a coordinate-free system in normal and ischemic hearts to gain mechanistic insight into normal valve function, valve dysfunction during ischemic mitral regurgitation (IMR), and the treatment effects of ring annuloplasty.
  
  
  RESULTS
  Radiopaque markers were implanted in sheep: 9 in the ventricle, 1 on each papillary tip, 8 around the mitral annulus, and 1 on each leaflet edge midpoint. One group served as a control (n=7); all others underwent flexible Tailor partial (n=5) or Duran complete (n=6) ring annuloplasty. After an 8+/-2-day recovery, 3D marker coordinates were measured with biplane videofluoroscopy before and during posterolateral left ventricular ischemia, and MR was assessed by color Doppler echocardiography. Papillary to annular distances remained constant throughout the cardiac cycle in normal hearts, during ischemia, and after ring annuloplasty with either type of ring. Papillary to leaflet edge distances similarly remained constant throughout ejection. During ischemia, however, the absolute distances from the papillary tips to the annulus changed in a manner consistent with leaflet tethering, and IMR was observed. In contrast, during ischemia in either ring group, those distances did not change from preischemia, and no IMR was observed.
  
  
  CONCLUSIONS
  This analysis uncovered a simple pattern of relatively constant intracardiac distances that describes the 3D geometry and dynamics of the papillary tips and leaflet edges from the dynamic mitral annulus. Ischemia perturbed the papillary-annular distances, and IMR occurred. Either type of ring annuloplasty prevented such changes, preserved papillary-annular distances, and prevented IMR.
authors.affiliation: Department of Cardiovascular and Thoracic Surgery, Stanford University School of Medicine, Stanford, CA 94305-5407, USA.
authors.forename: P
authors.initials: P
authors.lastname: Dagum
authors.forename: T A
authors.initials: TA
authors.lastname: Timek
authors.forename: G R
authors.initials: GR
authors.lastname: Green
authors.forename: D
authors.initials: D
authors.lastname: Lai
authors.forename: G T
authors.initials: GT
authors.lastname: Daughters
authors.forename: D H
authors.initials: DH
authors.lastname: Liang
authors.forename: M
authors.initials: M
authors.lastname: Hayase
authors.forename: N B
authors.initials: NB
authors.lastname: Ingels
authors.forename: D C
authors.initials: DC
authors.lastname: Miller
mesh_terms: D000818:Animals; D003287:Contrast Media; D004195:Disease Models, Animal; D018618:Echocardiography, Doppler, Color; D005471:Fluoroscopy; D019918:Heart Valve Prosthesis Implantation; D006439:Hemodynamics; D020007:Implants, Experimental; D008297:Male; D008943:Mitral Valve / Q000473:pathology / Q000503:physiopathology*; D008944:Mitral Valve Insufficiency / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology* / Q000601:surgery*; D017202:Myocardial Ischemia / Q000150:complications / Q000503:physiopathology*; D010210:Papillary Muscles / Q000000981:diagnostic imaging / Q000503:physiopathology; D012756:Sheep
chemical_list: D003287:Contrast Media