Document resource
Introduction Flow diverters (FDs) are frequently deployed across branches of the circle of Willis (CW) during treatment of complex intracranial aneurysms, covering the anterior cerebral artery (ACA), posterior cerebral artery (PCA), or communicating arteries while collateral pathways maintain distal perfusion. Clinical studies show that FD branch coverage can lead to vascular remodeling in both covered and non-target branches on follow-up, but the mechanisms underlying these global hemodynamic adjustments remain unclear. To examine immediate flow redistribution following branch coverage, CW models representing standard and hypoplastic anatomies were developed, and outlet flow was measured across ACA, middle cerebral artery (MCA), and PCA branches before and after FD placement. This study aimed to characterize network-wide flow redistribution and determine how baseline anatomy influences these patterns.Methods Four mechanically matched 3D-printed CW models were developed: one standard configuration and three hypoplastic variants involving the A1, PComA, and P1 segments. Each model was integrated into a pulsatile benchtop flow loop using a shear-thinning blood analog fluid. Physiologic flow distribution was established across six distal branches (ACAs, MCAs, and PCAs; total 564 mL/min). Four experimental conditions were tested in both standard and hypoplastic anatomies, involving deployment of three concentric Pipeline Embolization Devices (PEDs) with Shield Technology (Medtronic) across a branch origin (ACA, PCA, AComA, or PComA), with flow measured after each deployment ( figure 1A). Linear mixed-effects models evaluated branch-specific flow changes relative to baseline and differences between anatomies.Results FD deployment produced significant flow redistribution in both covered and non-target CW vessels. Covered vessels showed progressive flow reductions up to 14% after three FDs, particularly in hypoplastic anatomies ( figure 1B). Contralateral and collateral pathways also demonstrated measurable redistribution: contralateral ACA flow decreased by up to 4.7%, MCA flow increased by 2-5%, and PCA flow shifted by 3-8% depending on FD location. Several of these changes were statistically significant despite occurring in non-covered branches, highlighting the CW’s sensitivity to localized resistance changes.Conclusion FD placement across major CW branch origins produced immediate, anatomy-dependent alterations in cerebral hemodynamics. While flow predictably decreased in the covered vessel, substantial redistribution occurred in non-target branches, including contralateral and collateral pathways, and was often amplified or altered in hypoplastic variants. These findings provide a mechanical framework for clinically observed vascular remodeling, suggesting diameter changes may arise from network-wide redistribution rather than solely local flow reduction. Understanding anatomy-dependent redistribution has implications for procedural planning, including collateral reserve assessment and device deployment strategy.Disclosures S. Robertson: 5; C; Aneuvas Technologies, Inc.. F. Ramirez-Velandia: None. E. Mensah: None. J. Wells: 5; C; Aneuvas Technologies, Inc. W.E. Clark: 5; C; Aneuvas Technologies, Inc.. S. Schwartz: None. K. Lewis: 5; C; Aneuvas Technologies, Inc. H. Berns: 5; C; Aneuvas Technologies, Inc.. K. Hakes: None. C. Rapoport: None. M. Alnajrani: None. J. Granstein: None. T. Becker: 4; C; Aneuvas Technologies, Inc.. 5; C; Aneuvas Technologies, Inc.. C. Ogilvy: None.Abstract O-061 Figure 1Representative testing scenario showing flow diverter (FD) deployment across the anterior communicating artery (AComA) origin in (A) the standard circle of Willis (CW) model and (B) a variant with a hypoplastic left A1. Left: computer-aided design (CAD) rendering of the 3D-printed model illustrating FD placement. Right: corresponding percent change in terminal branch flow relative to baseline following sequential FD deployment. Error bars represent 95% confidence intervals of percent change relative to the pre-FD baseline