title: Endovascular treatment with flow diverters may fail to occlude experimental bifurcation aneurysms.
abstract: BACKGROUND
  Animal models may explain how stents and flow diverters (FDs) may succeed or fail to treat bifurcation aneurysms.
  
  
  METHODS
  In vitro studies were designed to anticipate device deformations in bifurcations. Large, wide-necked bifurcation aneurysms were constructed in 21 animals and treated 4-8 weeks later using stents and FDs in various combinations, forming four main groups: parent artery to right branch flow diversion (RBFD, n = 6), parent artery to left branch flow diversion (LBFD, n = 6), Y flow diversion (YFD, n = 4), and compared with high-porosity Y-stenting (YHPS, n = 4). The results include immediate and follow-up angiography at 3 months, followed by grading of the extent of neointimal coverage of devices at pathology.
  
  
  RESULTS
  In vitro, all braided devices showed varying porosities according to characteristic zones. FDs can be compacted to decrease porosities, but a limiting factor is the constant presence of a more porous transition zone. In vivo, 3/6 RBFD, 4/6 LBFD, and 2/4 YFD treated aneurysms had decreased in size by 3 months, while those treated with YHPS increased in size (P = 0.15). There was a significant correlation between device porosities and extent of neointimal coverage (r = 0.639, P = 0.002), and between porosities and angiographic evolution (r = -0.655, P = 0.002), but not between neointima formation and angiographic evolution (r = -0.278, P = 0.235). Failures could be explained in all cases by the presence of leaks or holes in the neointima at the level of the transition zones.
  
  
  CONCLUSIONS
  FDs did not successfully treat most bifurcation aneurysms, at least in this animal model.
authors.affiliation: Department of Radiology, Notre-Dame Hospital, Centre Hospitalier de l'Université de Montréal, 1560 Sherbrooke East, Montreal, QC, H2L 4M1, Canada, jean.raymond@umontreal.ca.
authors.forename: Jean
authors.initials: J
authors.lastname: Raymond
authors.forename: Tim E
authors.initials: TE
authors.lastname: Darsaut
authors.forename: Alina
authors.initials: A
authors.lastname: Makoyeva
authors.forename: Fabrice
authors.initials: F
authors.lastname: Bing
authors.forename: Igor
authors.initials: I
authors.lastname: Salazkin
mesh_terms: D000818:Animals; D001807:Blood Vessel Prosthesis; D002548:Cerebral Revascularization / Q000295:instrumentation* / Q000379:methods*; D004285:Dogs; D057510:Endovascular Procedures / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D002532:Intracranial Aneurysm / Q000175:diagnosis / Q000601:surgery*; D017211:Treatment Failure