title: Papillary muscle-left ventricular wall "complex".
abstract: OBJECTIVE
  Mitral valve homografts, despite theoretical advantages, are not widely used, in part because of lack of basic information about the three-dimensional geometry of the mitral apparatus.
  
  
  METHODS
  Radiopaque markers were used in the study of eight closed-chest dogs under four conditions: (1) baseline, (2) caval occlusion, (3) tachycardia (atrial pacing), and (4) nitroprusside infusion. Using a cylindrical coordinate system. defined with the origin at the midpoint between the anterior and posterior commissures, and the left ventricular long axis (z-axis), defined by the origin and the left ventricular apex, DTIP-MA (the z-coordinate [millimeters] of the papillary muscle tip), was measured at 10 time points throughout the entire cardiac cycle. DBASE-MA (the z-coordinate of the papillary muscle base) and LPM (the length of the papillary muscle [millimeters]) were also measured.
  
  
  RESULTS
  DTIP-MA varied slightly with time (p < 0.001 by analysis of variance), but the magnitude of change was negligible (< 0.9 mm) (e.g., DTIP-MA of the anterior papillary muscle was 20.7 +/- 2.7/20.8 +/- 2.8 [end-diastolic/end-systolic, mean +/- 1 standard deviation]; DTIP-MA of the posterior papillary muscle was 25.8 +/- 4.8/25.5 +/- 4.5). DTIP-MA was minimally influenced by the above perturbations. DBASE-MA and LPM of each papillary muscle, however, changed throughout the cardiac cycle (p < 0.001 by analysis of variance) by about 4 mm, and both parameters were dependent on loading conditions.
  
  
  CONCLUSIONS
  Papillary muscle length changed to keep the DTIP-MA distance constant such that the papillary muscle and left ventricular wall functioned together as a unit ("J-shaped complex"). These results provide a physiologic rationale for measuring DTIP-MA, define its potential surgical usefulness, and imply that using the entire length of the donor's papillary muscle (i.e., maintaining the entire J-shaped complex) is important in operations in which homograft or stentless xenograft mitral valves are used.
authors.affiliation: Department of Cardiovascular and Thoracic Surgery, Stanford University School of Medicine, Calif, USA.
authors.forename: M
authors.initials: M
authors.lastname: Komeda
authors.forename: J R
authors.initials: JR
authors.lastname: Glasson
authors.forename: A F
authors.initials: AF
authors.lastname: Bolger
authors.forename: G T
authors.initials: GT
authors.lastname: Daughters
authors.forename: N B
authors.initials: NB
authors.lastname: Ingels
authors.forename: D C
authors.initials: DC
authors.lastname: Miller
mesh_terms: D000818:Animals; D004285:Dogs; D006352:Heart Ventricles / Q000033:anatomy & histology*; D006439:Hemodynamics; D008943:Mitral Valve / Q000033:anatomy & histology*; D009200:Myocardial Contraction; D010210:Papillary Muscles / Q000033:anatomy & histology*