title: Y-stent coiling of basilar bifurcation aneurysms induces a dynamic angular vascular remodeling with alteration of the apical wall shear stress pattern.
abstract: BACKGROUND
  Although wide-necked basilar bifurcation aneurysms are treated with Y-stent coiling, the effect of this intervention on vessel configuration and hemodynamics is unknown.
  
  
  OBJECTIVE
  To investigate the immediate and delayed effects of Y-stenting using self-expanding microstents on basilar bifurcation architecture and hemodynamics.
  
  
  METHODS
  Fifteen patients underwent basilar Y-stent coiling and imaging with rotational angiography. Vascular angles were measured between proximal P1 segments of the posterior cerebral arteries (α) and between the basilar artery and each P1 segment (β(1,2)) in the anteroposterior and γ(1,2) sagittal planes. Patient-specific computational fluid dynamic analysis was used to estimate wall shear stress (WSS) changes with treatment.
  
  
  RESULTS
  In the anteroposterior plane, Y-stenting significantly decreased angle α and increased β angles immediately after stent coiling (P < .05 and P < .01, respectively) in a continued dynamic remodeling that progressed further in later months; sagittal γ angles also decreased (P < .0001). This novel stent-induced geometric progressive remodeling resulted in effective straightening and narrowing of the basilar bifurcation angle α (150.0 degrees vs 113 degrees, P < .0001) with significant correlation (r = 0.39, P < .05) between pretreatment proximal P1 angles and maximal angular change. Computational fluid dynamic analysis showed the angular remodeling led to significant narrowing of the WSS interpeak at the apex, redirecting high WSS away from the neck transition zone with native vessel toward the inert coil mass.
  
  
  CONCLUSIONS
  Y-configuration stent coiling induced immediate and, more significantly, a previously undefined delayed cerebrovascular remodeling. This progressive stent-induced angular remodeling alters perianeurysmal hemodynamics, independent of the flow-diverting properties of stent struts, thus shifting the balance of hemodynamic forces affecting aneurysm development and evolution.
authors.affiliation: Cerebrovascular and Endovascular Division, Department of Neurosurgery, Tufts Medical Center and Tufts University School of Medicine, Boston, MA, USA.
authors.forename: Bulang
authors.initials: B
authors.lastname: Gao
authors.forename: Merih I
authors.initials: MI
authors.lastname: Baharoglu
authors.forename: Alex D
authors.initials: AD
authors.lastname: Cohen
authors.forename: Adel M
authors.initials: AM
authors.lastname: Malek
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001488:Basilar Artery / Q000000981:diagnostic imaging* / Q000502:physiology / Q000601:surgery; D004621:Embolization, Therapeutic / Q000295:instrumentation* / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011859:Radiography; D033081:Shear Strength / Q000502:physiology; D015607:Stents; D016896:Treatment Outcome