title: Aortic hemodynamics after thoracic endovascular aortic repair, with particular attention to the bird-beak configuration.
abstract: OBJECTIVE
  To quantitatively evaluate the impact of thoracic endovascular aortic repair (TEVAR) on aortic hemodynamics, focusing on the implications of a bird-beak configuration.
  
  
  METHODS
  Pre- and postoperative CTA images from a patient treated with TEVAR for post-dissecting thoracic aortic aneurysm were used to evaluate the anatomical changes induced by the stent-graft and to generate the computational network essential for computational fluid dynamics (CFD) analysis. These analyses focused on the bird-beak configuration, flow distribution into the supra-aortic branches, and narrowing of the distal descending thoracic aorta. Three different CFD analyses (A: preoperative lumen, B: postoperative lumen, and C: postoperative lumen computed without stenosis) were compared at 3 time points during the cardiac cycle (maximum acceleration of blood flow, systolic peak, and maximum deceleration of blood flow).
  
  
  RESULTS
  Postoperatively, disturbance of flow was reduced at the bird-beak location due to boundary conditions and change of geometry after TEVAR. Stent-graft protrusion with partial coverage of the origin of the left subclavian artery produced a disturbance of flow in this vessel. Strong velocity increase and flow disturbance were found at the aortic narrowing in the descending thoracic aorta when comparing B and C, while no effect was seen on aortic arch hemodynamics.
  
  
  CONCLUSIONS
  CFD may help physicians to understand aortic hemodynamic changes after TEVAR, including the change in aortic arch geometry, the effects of a bird-beak configuration, the supra-aortic flow distribution, and the aortic true lumen dynamics. This study is the first step in establishing a computational framework that, when completed with patient-specific data, will allow us to study thoracic aortic pathologies and their endovascular management.
authors.affiliation: 1 Policlinico San Donato IRCCS, Thoracic Aortic Research Center, University of Milan, Italy.
authors.forename: Guido H W
authors.initials: GH
authors.lastname: van Bogerijen
authors.forename: Ferdinando
authors.initials: F
authors.lastname: Auricchio
authors.forename: Michele
authors.initials: M
authors.lastname: Conti
authors.forename: Adrien
authors.initials: A
authors.lastname: Lefieux
authors.forename: Alessandro
authors.initials: A
authors.lastname: Reali
authors.forename: Alessandro
authors.initials: A
authors.lastname: Veneziani
authors.forename: Jip L
authors.initials: JL
authors.lastname: Tolenaar
authors.forename: Frans L
authors.initials: FL
authors.lastname: Moll
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Rampoldi
authors.forename: Santi
authors.initials: S
authors.lastname: Trimarchi
mesh_terms: D001013:Aorta, Thoracic / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D017545:Aortic Aneurysm, Thoracic / Q000175:diagnosis / 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; D057510:Endovascular Procedures / Q000009:adverse effects / Q000295:instrumentation; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D009716:Numerical Analysis, Computer-Assisted; D011237:Predictive Value of Tests; D011474:Prosthesis Design; D011857:Radiographic Image Interpretation, Computer-Assisted; D015607:Stents; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
keywords: aorta; biomechanics; bird-beak; computational fluid dynamics; flow disturbance; stent-graft; thoracic endovascular aortic repair; true lumen narrowing