Flow diverters failing to occlude experimental bifurcation or curved sidewall aneurysms: an in vivo study in canines

Laboratory investigation

Restricted access


Flow diverters (FDs) are increasingly used to treat complex intracranial aneurysms, but preclinical studies that could guide clinical applications are lacking. The authors designed a modular aneurysm model in canines to address this problem.


Three variants of one modular aneurysm model were constructed in 21 animals. Sidewall (n = 5), curved sidewall (n = 5), and end-wall bifurcation (n = 7) aneurysms were treated with prototype 36-wire FDs. Four more end-wall bifurcation aneurysms were treated with prototype 48-wire lower-porosity FDs. Angiographic results postimplantation and at 3 months were scored with an ordinal scale. Animals were euthanized at 3 (n = 17) or 6 (n = 3) months, and the FD covering the aneurysm ostium was photographed to analyze metallic porosity and amount of neointima formation.


Straight sidewall aneurysms were better occluded than curved sidewall and end-wall bifurcation aneurysms at the 3-month angiography follow-up (p = 0.010). Flow diverters failed to occlude curved sidewall aneurysms (n = 0/5) and all but one (n = 1/7) end-wall bifurcation aneurysm. Angiographic results were no better (n = 0/4) using a 48-wire FD (p = 0.788). Branches jailed by the FD (n = 16) remained patent in all cases. Metallic porosity was decreased (p = 0.014) and neointimal closure of the aneurysm ostium was more complete (p = 0.040) in sidewall aneurysms than in curved or bifurcation variants of the model.


Flow diverters may succeed in treating straight sidewall aneurysms, but the same device repeatedly fails to occlude curved sidewall and end-wall bifurcation aneurysms. In vivo studies can be designed to test basic principles that, once validated, may serve to guide clinical use of new devices.

Abbreviations used in this paper:ASA = acetylsalicylic acid; CFD = computational fluid dynamic; FD = flow diverter; FSS = free segment of the stent.

Article Information

Address correspondence to: Jean Raymond, M.D., Department of Radiology, Centre Hospitalier de l'Université de Montréal–Notre-Dame Hospital, 1560 Sherbrooke East, Pavilion Simard, Rm Z12909, Montreal, Quebec H2L 4M1, Canada. email: jean.raymond@umontreal.ca.

Please include this information when citing this paper: published online May 4, 2012; DOI: 10.3171/2012.4.JNS111916.

© AANS, except where prohibited by US copyright law.



  • View in gallery

    Schematic representation of the 3 experimental canine aneurysm models, which feature constant blood vessel geometry and different directions of blood flow. A: Straight sidewall aneurysm model, with an arterial outflow directly opposite the aneurysm ostium, modeling a typical posterior communicating artery aneurysm. B: Curved sidewall model, with one outflow, modeling an ophthalmic artery aneurysm. C: End-wall bifurcation aneurysm, modeling a basilar or carotid artery bifurcation aneurysm. Note the linear or curving orientation of the FD used to treat the various aneurysms.

  • View in gallery

    Results of angiographic and pathological examination. Typical angiographic and pathological results after 3 months for straight sidewall aneurysms treated with a linear FD (A), curved sidewall aneurysms treated with a curving FD (B), and end-wall bifurcation aneurysms treated with a curving FD (C). Note the significantly denser metallic coverage (decreased metallic porosity) of the linear-deployed FD across the straight sidewall aneurysm, compared with curved sidewall and bifurcation aneurysms, treated with a curving FD. Neointimal coverage of the device over the straight sidewall aneurysm (A3) is more complete than that for the curved sidewall (B3) or end-wall (C3) aneurysms.

  • View in gallery

    Neointimal coverage of devices. Microscopic photograph of straight sidewall aneurysm treated with an FD (A, arterial view) and end-wall bifurcation aneurysm treated with a curving FD (B, aneurysm view). Note the complete, mature tissue coverage of the FD struts in the straight sidewall situation. The bifurcation aneurysm is widely patent, and open pores can be seen at the level of the FD, feeding the aneurysm sac and the ostium of the branch (asterisk). Histological cross-section (C) through the thick neointima that closes the FD pores at the level of the neck of a straight sidewall aneurysm. Histological cross-section (D) of the FD at the level of the ostium of an end-wall bifurcation aneurysm, by comparison, showing opened pores only partially occluded with fibrin and red blood cells.

  • View in gallery

    Effects of curvature on porosity. Microscopic photographs of Prototype FD (upper) and Pipeline FD (lower) curved to illustrate the effects of deformation on increased device porosity on the convex, in contrast to the concave side of the curvature.


  • 1

    Appanaboyina SMut FLöhner RPutman CCebral J: Simulation of intracranial aneurysm stenting: techniques and challenges. Comput Methods Appl Mech Eng 198:356735822009

  • 2

    Appanaboyina SMut FLöhner RPutman CMCebral JR: Computational fluid dynamics of stented intracranial aneurysms using adaptive embedded unstructured grids. Int J Numer Methods Fluids 57:4754932008

  • 3

    Aurboonyawat TBlanc RSchmidt PPiotin MSpelle LNakib A: An in vitro study of silk stent morphology. Neuroradiology 53:6596672011

  • 4

    Byrne JVBeltechi RYarnold JABirks JKamran M: Early experience in the treatment of intra-cranial aneurysms by endovascular flow diversion: a multicentre prospective study. PLoS ONE 5:piie124922010

  • 5

    Cebral JRCastro MAAppanaboyina SPutman CMMillan DFrangi AF: Efficient pipeline for image-based patient-specific analysis of cerebral aneurysm hemodynamics: technique and sensitivity. IEEE Trans Med Imaging 24:4574672005

  • 6

    Darsaut TEBing FGevry GSalazkin IRaymond J: Flow diverters can occlude aneurysms and preserve arterial branches: a new experimental model. AJNR Am J Neuroradiol [in press]2012

  • 7

    Darsaut TEBing FSalazkin IGevry GRaymond J: Testing flow diverters in giant fusiform aneurysms: a new experimental model can show leaks responsible for failures. AJNR Am J Neuroradiol 32:217521792011

  • 8

    Fiorella DAlbuquerque FCDeshmukh VRWoo HHRasmussen PAMasaryk TJ: Endovascular reconstruction with the Neuroform stent as monotherapy for the treatment of uncoilable intradural pseudoaneurysms. Neurosurgery 59:2913002006

  • 9

    Fiorella DAlbuquerque FCWoo HRasmussen PAMasaryk TJMcDougall CG: Neuroform in-stent stenosis: incidence, natural history, and treatment strategies. Neurosurgery 59:34422006

  • 10

    Fiorella DHsu DWoo HHTarr RWNelson PK: Very late thrombosis of a pipeline embolization device construct: case report. Neurosurgery 67:onsE313onsE3142010

  • 11

    Fiorella DSadasivan CWoo HHLieber B: Regarding “Aneurysm rupture following treatment with flow-diverting stents: computational hemodynamics analysis of treatment”. AJNR Am J Neuroradiol 32:E95E1002011

  • 12

    Ford MDLee SWLownie SPHoldsworth DWSteinman DA: On the effect of parent-aneurysm angle on flow patterns in basilar tip aneurysms: towards a surrogate geometric marker of intra-aneurismal hemodynamics. J Biomech 41:2412482008

  • 13

    Hassan TAhmed YMHassan AA: The adverse effects of flow-diverter stent-like devices on the flow pattern of saccular intracranial aneurysm models: computational fluid dynamics study. Acta Neurochir (Wien) 153:163316402011

  • 14

    Kallmes DFDing YHDai DKadirvel RLewis DACloft HJ: A new endoluminal, flow-disrupting device for treatment of saccular aneurysms. Stroke 38:234623522007

  • 15

    Kallmes DFDing YHDai DKadirvel RLewis DACloft HJ: A second-generation, endoluminal, flow-disrupting device for treatment of saccular aneurysms. AJNR Am J Neuroradiol 30:115311582009

  • 16

    Kim MTaulbee DBTremmel MMeng H: Comparison of two stents in modifying cerebral aneurysm hemodynamics. Ann Biomed Eng 36:7267412008

  • 17

    Kim YHKim JEIto YShih AMBrott BAnayiotos A: Hemodynamic analysis of a compliant femoral artery bifurcation model using a fluid structure interaction framework. Ann Biomed Eng 36:175317632008

  • 18

    Kulcsár ZErnemann UWetzel SGBock AGoericke SPanagiotopoulos V: High-profile flow diverter (silk) implantation in the basilar artery: efficacy in the treatment of aneurysms and the role of the perforators. Stroke 41:169016962010

  • 19

    Lieber BBGounis MJ: The physics of endoluminal stenting in the treatment of cerebrovascular aneurysms. Neurol Res 24:Suppl 1S33S422002

  • 20

    Lylyk PMiranda CCeratto RFerrario AScrivano ELuna HR: Curative endovascular reconstruction of cerebral aneurysms with the pipeline embolization device: the Buenos Aires experience. Neurosurgery 64:6326432009

  • 21

    Meng HWang ZKim MEcker RDHopkins LN: Saccular aneurysms on straight and curved vessels are subject to different hemodynamics: implications of intravascular stenting. AJNR Am J Neuroradiol 27:186118652006

  • 22

    Mut FAppanaboyina SCebral JR: Simulation of stent deployment in patient-specific cerebral aneurysm models for their hemodynamics analysis. Proceedings of the Summer Bioengineering Conference of the American Society of Mechanical EngineersMarco Island, Florida2008

  • 23

    Naggara ODarsaut TESalazkin ISoulez GGuilbert FRoy D: A new canine carotid artery bifurcation aneurysm model for the evaluation of neurovascular devices. AJNR Am J Neuroradiol 31:9679712010

  • 24

    Sadasivan CCesar LSeong JRakian AHao QTio FO: An original flow diversion device for the treatment of intracranial aneurysms: evaluation in the rabbit elastase-induced model. Stroke 40:9529582009

  • 25

    Szikora IBerentei ZKulcsar ZMarosfoi MVajda ZSLee W: Treatment of intracranial aneurysms by functional reconstruction of the parent artery: the Budapest experience with the pipeline embolization device. AJNR Am J Neuroradiol 31:113911472010


Cited By



All Time Past Year Past 30 Days
Abstract Views 124 124 18
Full Text Views 137 137 1
PDF Downloads 126 126 1
EPUB Downloads 0 0 0


Google Scholar