title: The concept of aortic replacement based on computational fluid dynamic analysis: patient-directed aortic replacement.
abstract: OBJECTIVE
  Aortic replacement is based on the aortic diameter in the absence of dissection or connective tissue diseases. Frequently, a number of different aortic-to-prosthetic anastomotic positions are possible depending on patient factors and surgeon preferences. High stress on residual aortic tissue may result in aneurysm formation or aneurysmal dilatation. Utilizing a computational fluid dynamic evaluation, we aimed to define possible optimal operative interventions with regard to the extent of aortic replacement.
  
  
  METHODS
  For proof of principle, a computational fluid dynamic (CFD) analysis, using Fluent 6.2 (Ansys UK Ltd, Sheffield, UK), was performed on a simplified ascending arch and descending aortic geometry. Wall shear stress in three dimensions was assessed for the standard operations: ascending aortic replacement, arch replacement and proximal descending aortic replacement.
  
  
  RESULTS
  Hermiarch replacement is superior to isolated ascending aortic replacement with regard to residual stress analysis on tissues (up to a 10-fold reduction). Aortic arch replacement with island implantation of the supra-aortic vessels may potentially result in high stress on the residual aorta (10-fold increase). Aortic arch replacement with individual supra-aortic vessel implantation may result in areas of high stress (10-fold increase) on native vessels if an inadequate length of supra-aortic tissue is not resected, regardless of it being aneurysmal.
  
  
  CONCLUSIONS
  Computational fluid dynamic evaluation, which will have to be patient-specific, 3D anatomical and physiological, potentially has enormous implications for operative strategy in aortic replacement surgery. CFD analysis may direct the replacement of normal-diameter aortas in the future.
authors: School of Engineering, University of Liverpool, UK.
authors: Laurant
authors: L
authors: Heim
authors: Robert J
authors: RJ
authors: Poole
authors: Richard
authors: R
authors: Warwick
authors: Michael
authors: M
authors: Poullis
mesh_terms: D001011:Aorta / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D001013:Aorta, Thoracic / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D001018:Aortic Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D001027:Aortography / Q000379:methods; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation; D003198:Computer Simulation; D006439:Hemodynamics; D006801:Humans; D021621:Imaging, Three-Dimensional; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D011857:Radiographic Image Interpretation, Computer-Assisted; D013314:Stress, Mechanical; D025321:Surgery, Computer-Assisted / Q000009:adverse effects / Q000295:instrumentation; D014057:Tomography, X-Ray Computed