title: The sinus of Valsalva relieves abnormal stress on aortic valve leaflets by facilitating smooth closure.
abstract: OBJECTIVE
  Recently, various modifications have been made to aortic root replacement procedures to include the pseudosinus in the synthetic graft, but its effect on valve function still remains to be elucidated. The purpose of this study was to compare the flow dynamics and its influence on the stress/strain in the valve leaflet in two types of aortic root, either with or without the pseudosinus, with a simulation model.
  
  
  METHODS
  The proximal portions of the ascending aorta and aortic valves were modeled with blood flowing inside. Blood flow and the motion of aortic valve leaflets were studied while applying a physiologic pressure waveform using fluid-structure interaction finite element analysis. Waveforms were varied to simulate the change in cardiac contractility.
  
  
  RESULTS
  In the aorta without the sinus, the time during which the valve was open was longer and the rapid valve closing velocity was faster under all conditions studied. In the pseudosinus model, we could clearly observe vortex formation from the early phase of ejection, which seemed to facilitate the gradual but smooth closure of the valve. Valve leaflets without the sinus were subject to greater stress and underwent bending deformation in the longitudinal direction.
  
  
  CONCLUSIONS
  Sinuses of Valsalva facilitate the smooth closure of the aortic valve, thereby avoiding the building up of abnormal stress in the leaflet. Such an effect may assure the durability of valve leaflets in aortic grafts with a pseudosinus.
authors.affiliation: Department of Human and Engineered Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa-shi, Chiba, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Katayama
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Umetani
authors.forename: Seiryo
authors.initials: S
authors.lastname: Sugiura
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Hisada
mesh_terms: D001011:Aorta / Q000502:physiology*; D001021:Aortic Valve / Q000502:physiology*; D001775:Blood Circulation / Q000502:physiology; D020342:Finite Element Analysis; D006801:Humans; D008955:Models, Cardiovascular; D012039:Regional Blood Flow; D012850:Sinus of Valsalva / Q000502:physiology*; D013312:Stress, Physiological