title: Numerical model of the aortic root and valve: optimization of graft size and sinotubular junction to annulus ratio.
abstract: OBJECTIVE
  The aim of this study was to determine the influence of aortic annulus (AA) diameter and the ratio of the sinotubular junction (STJ) diameter to the AA diameter on aortic valve hemodynamics and tissue mechanics and to suggest optimal values.
  
  
  METHODS
  Sixteen cases of aortic roots with AA diameters between 22 and 28 mm and an STJ/AA diameter ratio between 0.8 and 1.4 were numerically modeled. Average coaptation height and mechanical stresses were calculated from 3-dimensional finite element analysis of the aortic valve and root. Five additional fluid structure interaction (FSI) models with an AA diameter of 24 mm and an STJ/AA ratio between 0.6 and 1.4 were also constructed. The material properties of the tissues were from porcine valves and boundary conditions were physiologic and normal blood pressures.
  
  
  RESULTS
  In most cases, average coaptation height decreased with an increase in the STJ/AA ratio. Those cases with AA diameters between 24 and 26 mm and an STJ/AA ratio between 0.8 and 1.0 had a relatively large average coaptation height (>3 mm) and similar stress distribution during diastole. The flow shear stress values on the cusps at peak systole increased at the same time as the STJ/AA ratio decreased, similar to the opening area.
  
  
  CONCLUSIONS
  Relatively large coaptation, low stress in the tissues during diastole, and low flow shear stress during systole is the best combination for cases of AA diameter between 24 and 26 mm with identical STJ diameter. Valve-sparing procedures that prevent AA expansion are preferable.
authors: School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel.
authors: Gil
authors: G
authors: Marom
authors: Rotem
authors: R
authors: Halevi
authors: Rami
authors: R
authors: Haj-Ali
authors: Moshe
authors: M
authors: Rosenfeld
authors: Hans-Joachim
authors: HJ
authors: Schäfers
authors: Ehud
authors: E
authors: Raanani
mesh_terms: D000818:Animals; D001011:Aorta / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D001021:Aortic Valve / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D001696:Biomechanical Phenomena; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000295:instrumentation*; D003198:Computer Simulation; D017076:Computer-Aided Design; D020342:Finite Element Analysis; D006439:Hemodynamics; D006801:Humans; D008955:Models, Cardiovascular; D009716:Numerical Analysis, Computer-Assisted; D011474:Prosthesis Design; D013314:Stress, Mechanical; D013552:Swine
keywords: 35.1; AA; FSI; STJ; aortic annulus; aortic annulus diameter; average coaptation height; d(AA); d(STJ); fluid–structure interaction; sinotubular junction; sinotubular junction diameter