title: The bird beak configuration has no adverse effect in a magnetic resonance functional analysis of thoracic stent grafts after traumatic aortic transection.
abstract: BACKGROUND
  This study used magnetic resonance imaging (MRI) to analyze functional long-term outcome after endovascular repair of blunt aortic injury.
  
  
  METHODS
  This prospective study enrolled 27 of 53 patients who were treated between 1999 and 2008. Patients underwent functional multidimensional contrast-enhanced MRI with flow analysis or compliance measurements of the aorta, or both. Ten patients were treated with the Medtronic Valiant (Medtronic World Medical, Sunrise, Fla), 14 patients received a Gore TAG (W. L. Gore & Associates, Flagstaff, Ariz), and two received a C (conformable)-TAG (W. L. Gore & Associates) stent graft. For several patients, repetitive measurements over time could be done. Median follow-up was 3.92 ± 2.7 years. The MRI parameters were: three-dimensional flow: echo time/repetition time = 3.1/5.3 ms, Δx(pixel density) = 2.5 × 2.5 × 3 mm(3); respiratory navigator, α = 15°, venc(encoding velocity) = 200 cm/s along anterior-posterior, right-left, and foot-head direction, 40 cardiac phases. Cine: echo time/repetition time = 1.7/3.4 ms, Δx(pixel density) = 1.2 × 1.2 × 6 mm(3), breathhold, α = 60°, 40 cardiac phases.
  
  
  RESULTS
  The flow analysis showed flow acceleration at the proximal end of the stent graft, with higher values in patients with a nonoptimal alignment of the stent graft. No differences were found between different devices (median acceleration was 75.99 ± 37.98 cm/s for Gore and 71.59 ± 17.22 cm/s for Medtronic). The values were stable during follow-up. In the compliance analysis, the part of the aorta covered with the stent graft showed nearly no expansion, whereas the ascending and descending aorta showed normal expansion. This behavior did not change over the time. At the proximal end of the stent graft, a slight compression could be noted (-0.5 ± 0.14 mm), except in those patients with a C-TAG device from Gore.
  
  
  CONCLUSIONS
  Functional analysis showed no adverse long-term outcome of the bird beak configuration of stent grafts in the aortic arch after endovascular repair after blunt aortic injury.
authors.affiliation: Department of Vascular and Endovascular Surgery, University of Düsseldorf, Düsseldorf, Germany. Electronic address: alexander.oberhuber@corones.it.
authors.forename: Alexander
authors.initials: A
authors.lastname: Oberhuber
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, University of Ulm, Ulm, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Schabhasian
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, University of Ulm, Ulm, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Kohlschmitt
authors.affiliation: Department of Internal Medicine II, University of Ulm, Ulm, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Rottbauer
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, University of Ulm, Ulm, Germany.
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Orend
authors.affiliation: Department of Internal Medicine II, University of Ulm, Ulm, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Rasche
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001013:Aorta, Thoracic / Q000293:injuries / Q000503:physiopathology / Q000601:surgery*; D001783:Blood Flow Velocity; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation*; D002648:Child; D057510:Endovascular Procedures / Q000009:adverse effects / Q000295:instrumentation*; D005260:Female; D006439:Hemodynamics; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011474:Prosthesis Design; D012039:Regional Blood Flow; D015607:Stents; D013898:Thoracic Injuries / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome; D057772:Vascular System Injuries / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D014949:Wounds, Nonpenetrating / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D055815:Young Adult