title: Role of the bloodstream impacting force and the local pressure elevation in the rupture of cerebral aneurysms.
abstract: OBJECTIVE
  Inertial force of the bloodstream results in the local elevation of intravascular pressure secondary to flow impact. Previous studies suggest that this "impacting force" and the local pressure elevation at the aneurysm may have a large contribution to the development of cerebral aneurysms. The goal of the present study is to evaluate how the bloodstream impacting force and the local pressure elevation at the aneurysm influences the rupture of cerebral aneurysms.
  
  
  METHODS
  A total of 29 aneurysms were created in 26 patient-specific vessel models, and computer simulations were used to calculate pressure distributions around the vessel branching points and the aneurysms.
  
  
  RESULTS
  Direct impact of the parent artery bloodstream resulted in local elevation in pressure at branch points, and bends in arteries (231.2+/-198.1 Pa; 100 Pa=0.75 mm Hg). The bloodstream entered into the aneurysm with a decreased velocity after it impacted on the branching points or bends. Thus, the flow impact at the aneurysm occurred usually weakly. At the top or the rupture point of the aneurysm, the flow velocity was always delayed. The local pressure elevation at the aneurysm was 119.3+/-91.2 Pa.
  
  
  CONCLUSIONS
  The pressure elevation at the area of flow impact and at the aneurysm constituted only 1% to 2% of the peak intravascular pressure. The results suggest that the bloodstream impacting force and the local pressure elevation at the aneurysm may have less contribution to the rupture of cerebral aneurysms than was expected previously.
authors.affiliation: Department of Neurosurgery, Faculty of Medicine, University of Tokyo, Japan. mshoji-tky@umin.ac.jp
authors.forename: Masaaki
authors.initials: M
authors.lastname: Shojima
authors.forename: Marie
authors.initials: M
authors.lastname: Oshima
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Takagi
authors.forename: Ryo
authors.initials: R
authors.lastname: Torii
authors.forename: Kazuya
authors.initials: K
authors.lastname: Nagata
authors.forename: Ichiro
authors.initials: I
authors.lastname: Shirouzu
authors.forename: Akio
authors.initials: A
authors.lastname: Morita
authors.forename: Takaaki
authors.initials: T
authors.lastname: Kirino
mesh_terms: D000368:Aged; D017542:Aneurysm, Ruptured / Q000473:pathology / Q000503:physiopathology*; D015901:Angiography, Digital Subtraction; D001775:Blood Circulation; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation; D003198:Computer Simulation; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007091:Image Processing, Computer-Assisted; D002532:Intracranial Aneurysm / Q000175:diagnosis* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D008962:Models, Theoretical; D011312:Pressure; D013314:Stress, Mechanical