title: Impact of poroelasticity of intraluminal thrombus on wall stress of abdominal aortic aneurysms.
abstract: BACKGROUND
  The predictions of stress fields in Abdominal Aortic Aneurysm (AAA) depend on constitutive descriptions of the aneurysm wall and the Intra-luminal Thrombus (ILT). ILT is a porous diluted structure (biphasic solid-fluid material) and its impact on AAA biomechanics is controversially discussed in the literature. Specifically, pressure measurements showed that the ILT cannot protect the wall from the arterial pressure, while other (numerical and experimental) studies showed that at the same time it reduces the stress in the wall.
  
  
  METHODS
  To explore this phenomenon further a poroelastic description of the ILT was integrated in Finite Element (FE) Models of the AAA. The AAA model was loaded by a pressure step and a cyclic pressure wave and their transition into wall tension was investigated. To this end ILT's permeability was varied within a microstructurally motivated range.
  
  
  RESULTS
  The two-phase model verified that the ILT transmits the entire mean arterial pressure to the wall while, at the same time, it significantly reduces the stress in the wall. The predicted mean stress in the AAA wall was insensitive to the permeability of the ILT and coincided with the results of AAA models using a single-phase ILT description.
  
  
  CONCLUSIONS
  At steady state, the biphasic ILT behaves like a single-phase material in an AAA model. Consequently, computational efficient FE single-phase models, as they have been exclusively used in the past, accurately predict the wall stress in AAA models.
authors.affiliation: Department of Solid Mechanics, Brno University of Technology, Technicka 2896/2, Brno 616 69, Czech Republic. polzer@seznam.cz
authors.forename: Stanislav
authors.initials: S
authors.lastname: Polzer
authors.forename: T Christian
authors.initials: TC
authors.lastname: Gasser
authors.forename: Bernd
authors.initials: B
authors.lastname: Markert
authors.forename: Jiri
authors.initials: J
authors.lastname: Bursa
authors.forename: Pavel
authors.initials: P
authors.lastname: Skacel
mesh_terms: D017544:Aortic Aneurysm, Abdominal / Q000503:physiopathology*; D001794:Blood Pressure; D004548:Elasticity; D020342:Finite Element Analysis; D006801:Humans; D016062:Porosity; D013314:Stress, Mechanical; D013927:Thrombosis / Q000503:physiopathology*