title: Intra-aneurysmal pressure and flow changes induced by flow diverters: relation to aneurysm size and shape.
abstract: OBJECTIVE
  Effects of blood flow modification by flow diverters are observed to lead often to aneurysm thrombosis and reverse remodeling. For this process, to further understand the potential roles of intra-aneurysmal blood pressure changes and aneurysm morphologies, 23 patients were studied by numeric simulation.
  
  
  METHODS
  3D imaging of aneurysms of different sizes and shapes, all located at the supraclinoid segment of the ICA (n=23), was prepared for CFD simulations. Hemodynamic variables were calculated for conditions before and after virtual FD implantation, reconstituting a vessel wall scaffold across the aneurysm neck. WSS, velocity, residence time, turnover time, and intra-aneurysmal pressure were assessed statistically.
  
  
  RESULTS
  After placement of FDs, significant reductions inside the aneurysm were observed for most hemodynamic variables (P<.01) except mean intra-aneurysmal pressures. For minimum/maximum intra-aneurysmal pressure values, small but significant changes were found; however, they were considered too small to be of relevance.
  
  
  CONCLUSIONS
  Calculations in 23 cases did not reveal significant intra-aneurysmal mean or peak pressure changes, indicating a minor role of pressure changes in the rare event of secondary ruptures after FD use. Other hemodynamic variables (WSS and velocity) exhibited more significant changes, indicating their role in intra-aneurysmal thrombus formation. Size-dependent, significantly higher reduction in WSS (P=.069) and velocity (P=.013) was observed in small aneurysms compared with larger ones. When it came to shape, there were significantly higher reductions in WSS (P=.055) and velocity (P=.065) and a significantly higher increase in turnover time in fusiform aneurysms compared with saccular aneurysms.
authors.affiliation: Networking Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine, Barcelona, Spain. ignacio.larrabide@upf.edu
authors.forename: I
authors.initials: I
authors.lastname: Larrabide
authors.forename: M L
authors.initials: ML
authors.lastname: Aguilar
authors.forename: H G
authors.initials: HG
authors.lastname: Morales
authors.forename: A J
authors.initials: AJ
authors.lastname: Geers
authors.forename: Z
authors.initials: Z
authors.lastname: Kulcsár
authors.forename: D
authors.initials: D
authors.lastname: Rüfenacht
authors.forename: A F
authors.initials: AF
authors.lastname: Frangi
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003198:Computer Simulation; D016208:Databases, Factual; D057510:Endovascular Procedures; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D002532:Intracranial Aneurysm / Q000145:classification / Q000503:physiopathology* / Q000628:therapy; D008955:Models, Cardiovascular; D013927:Thrombosis / Q000503:physiopathology; D014655:Vascular Resistance / Q000502:physiology