title: Effect of curvature on displacement forces acting on aortic endografts: a 3-dimensional computational analysis.
abstract: OBJECTIVE
  To determine the effect of curvature on the magnitude and direction of displacement forces acting on aortic endografts in 3-dimensional (3D) computational models.
  
  
  METHODS
  A 3D computer model was constructed based on magnetic resonance angiography data from a patient with an infrarenal aortic aneurysm. Computational fluid dynamics tools were used to simulate realistic flow and pressure conditions of the patient. An aortic endograft was deployed in the model, and the displacement forces acting on the endograft were calculated and expressed in Newtons (N). Additional models were created to determine the effects of reducing endograft curvature, neck angulation, and iliac angulation on displacement forces.
  
  
  RESULTS
  The aortic endograft had a curved configuration as a result of the patient's anatomy, with curvature in the anterolateral direction. Total displacement force acting on the endograft was 5.0 N, with 28% of the force in a downward (caudal) direction and 72% of the force in a sideways (anterolateral) direction. Elimination of endograft curvature (planar graft configuration) reduced total displacement force to 0.8 N, with the largest component of force (70%) acting in the sideways direction. Straightening the aortic neck in the curved endograft configuration reduced the total force acting on the endograft to 4.2 N, with a reduction of the sideways component to 55% of the total force. Straightening the iliac limbs of the endograft reduced the total force acting on the endograft to 2.1 N but increased the sideways component to 91% of the total force.
  
  
  CONCLUSIONS
  The largest component of the force acting on the aortic endograft is in the sideways direction, with respect to the blood flow, rather than in the downward (caudal) direction as is commonly assumed. Increased curvature of the aortic endograft increases the magnitude of the sideways displacement force. The degree of angulation of the proximal and distal ends of the endograft influence the magnitude and direction of displacement force. These factors may have a significant influence on the propensity of endografts to migrate in vivo.
authors: Department of Bioengineering, Stanford University, Stanford, California, USA.
authors: C Alberto
authors: CA
authors: Figueroa
authors: Charles A
authors: CA
authors: Taylor
authors: Victoria
authors: V
authors: Yeh
authors: Allen J
authors: AJ
authors: Chiou
authors: Christopher K
authors: CK
authors: Zarins
mesh_terms: D001014:Aortic Aneurysm / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy*; D001807:Blood Vessel Prosthesis; D019295:Computational Biology; D019544:Equipment Failure Analysis; D018056:Hemorheology; D006801:Humans; D021621:Imaging, Three-Dimensional; D018810:Magnetic Resonance Angiography; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D011859:Radiography; D033081:Shear Strength; D013314:Stress, Mechanical