title: Aortic compliance following EVAR and the influence of different endografts: determination using dynamic MRA.
abstract: OBJECTIVE
  To utilize dynamic magnetic resonance angiography (MRA) to characterize aortic stiffness (beta) and elastic modulus (Ep) as indexes of wall compliance during the cardiac cycle and determine any influence of different endograft designs or the presence of endoleaks on these indexes.
  
  
  METHODS
  Eleven consecutive patients (11 men; median age 74 years, range 63-78) with abdominal aortic aneurysm (AAA) selected for endovascular repair were scanned pre- and postoperatively. Aortic area and diameter changes during the cardiac cycle were determined using dynamic MRA at 4 levels: 3 cm above the renal arteries, between the renal arteries, 1 cm below the renal arteries, and at the level of maximum aneurysm sac diameter. Ep and beta were calculated. Data are presented as median (range); p<0.05 was considered significant.
  
  
  RESULTS
  Preoperatively, Ep and beta were significantly higher at the level of the aneurysm sac compared to all other levels (p<0.05). Following EVAR, stiffness increased at this level (p<0.05). After implantation, patients with an Excluder endograft demonstrated Ep and beta measurements at the aneurysm neck that were 94% and 60% higher, respectively, compared to those with a Talent (p<0.05) endograft. The presence of an endoleak had no effect on Ep or beta.
  
  
  CONCLUSIONS
  This study introduces the feasibility of dynamic MRA imaging-based calculations of aortic elastic modulus and stiffness. AAA patients demonstrate increased Ep and beta at the level of the aneurysm sac. EVAR results in increased aneurysm sac Ep and beta. Stent-graft design seems to alter Ep and beta within the aneurysm neck, which may have consequences for endograft durability. The presence of an endoleak does not seem to have an effect on Ep or beta.
authors.affiliation: Department of Vascular Surgery, University Medical Center, Utrecht, The Netherlands. H.Verhagen@umcutrecht.nl
authors.forename: Joost A
authors.initials: JA
authors.lastname: van Herwaarden
authors.forename: Bart E
authors.initials: BE
authors.lastname: Muhs
authors.forename: Koen L
authors.initials: KL
authors.lastname: Vincken
authors.forename: Joffrey
authors.initials: J
authors.lastname: van Prehn
authors.forename: Arno
authors.initials: A
authors.lastname: Teutelink
authors.forename: Lambertus W
authors.initials: LW
authors.lastname: Bartels
authors.forename: Frans L
authors.initials: FL
authors.lastname: Moll
authors.forename: Hence J M
authors.initials: HJ
authors.lastname: Verhagen
mesh_terms: D000368:Aged; D017130:Angioplasty; D001011:Aorta / Q000503:physiopathology* / Q000601:surgery; D017544:Aortic Aneurysm, Abdominal / Q000503:physiopathology / Q000601:surgery*; D001807:Blood Vessel Prosthesis; D003187:Compliance; D005240:Feasibility Studies; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D011475:Prosthesis Failure; D011673:Pulsatile Flow; D015607:Stents