title: Sonometric study of the normal tricuspid valve annulus in sheep.
abstract: OBJECTIVE
  Mitral valve dynamic changes during the cardiac cycle have been previously studied in sheep using sonomicrometry. The study aim was to analyze geometric changes of the normal tricuspid annulus in sheep using a similar methodology. This is most likely the first tricuspid valve study using high temporal resolution (200 Hz = 200 data points per second).
  
  
  METHODS
  Thirteen crystals were implanted in seven sheep along the annulus (n = 6), at the tips of papillary muscles (n = 3), at the free edge of the leaflets (n = 3), and at the apex of the left ventricle (n = 1). Recordings (10 s) of crystal distances were used to create a three-dimensional (3D) coordinate system based on the least-squares plane of the annulus, and maximum and minimum values were calculated for length, area, and position in xyz coordinates.
  
  
  RESULTS
  During the cardiac cycle, the tricuspid annulus area expanded 28.6 +/- 3.6% with similar maximum expansions of each segment along the annulus: septal (10.4 +/- 1.2%), anterior (13.0 +/- 1.5%), and posterior (14.0 +/- 1.6%). The annulus was saddle-shaped, with a circumferential expansion from elliptical at minimum area to more circular at maximum area. The time delay to maximum leaflet area and maximum papillary area occurred 83 +/- 13 ms and 279 +/- 30 ms respectively after maximum annulus area.
  
  
  CONCLUSIONS
  The tricuspid valve undergoes continual and complex geometric changes during the cardiac cycle. In addition, the annulus expands significantly due to similar increases in length of the septal and free wall segments. The annulus is not in a single plane, but is saddle-shaped. The expansion and contraction of the tricuspid valve complex is stepwise, and sequential from base to apex.
authors.affiliation: International Heart Institute of Montana Foundation, St. Patrick Hospital and Health Sciences Center, University of Montana, Missoula, Montana, USA.
authors.forename: Matthew E
authors.initials: ME
authors.lastname: Hiro
authors.forename: Jerome
authors.initials: J
authors.lastname: Jouan
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Pagel
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Lansac
authors.forename: Khee Hiang
authors.initials: KH
authors.lastname: Lim
authors.forename: Hou-Sen
authors.initials: HS
authors.lastname: Lim
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Duran
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D018618:Echocardiography, Doppler, Color; D006439:Hemodynamics; D008955:Models, Cardiovascular; D009200:Myocardial Contraction; D010210:Papillary Muscles / Q000000981:diagnostic imaging / Q000502:physiology; D012016:Reference Values; D012756:Sheep; D014261:Tricuspid Valve / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D016277:Ventricular Function, Left