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Implantation of Pipeline Flow-Diverting Stents Reduces Aneurysm Inflow Without Relevantly Affecting Static Intra-aneurysmal Pressure

Kerl, Hans U. MD*; Boll, Hanne DVM*; Fiebig, Teresa DVM*; Figueiredo, Giovanna MD*; Förster, Alex MD*; Nölte, Ingo S. MD*; Nonn, Andrea DVM; Groden, Christoph MD*; Brockmann, Marc A. MD*,‡

doi: 10.1227/NEU.0000000000000253

BACKGROUND: Flow-diverting stent (FDS) implantation is an endovascular treatment option for intracranial aneurysms. However, little is known about the hemodynamic effects.

OBJECTIVE: To assess the effect of stent compression on FDS porosity, to evaluate the influence of single and overlapping implantation of FDS on intra-aneurysmal flow profiles, and to correlate stent porosity with changes in static mean intra-aneurysmal pressure.

METHODS: Intra-aneurysmal time-density curves were recorded in a pulsatile in vitro flow model before and after implantation of FDSs (Pipeline Embolization Device; ev3) in 7 different types of aneurysm models. Reductions in the maximum contrast inflow and time to maximum intra-aneurysmal contrast were calculated. Micro--computed tomography was performed, and compression-related FDS porosity was measured. The influence of FDS placement on mean static intra-aneurysmal pressure was measured.

RESULTS: FDS compression resulted in an almost linear reduction in stent porosity. Stent porosity (struts per 1 mm) correlated significantly with the reduction of aneurysm contrast inflow (R2 = 0.81, P < .001) and delay until maximum contrast (R2 = 0.34, P = .001). Circulating intra-aneurysmal high-velocity flow was terminated in all sidewall models after implantation of a single stent. Superimposition of 2 stents reduced maximum intra-aneurysmal contrast by 69.1 ± 3.1% (mean ± SD) in narrow-necked sidewall aneurysm models, whereas no substantial reduction in maximum intra-aneurysmal contrast was observed in wide-necked sidewall aneurysm models. Intra-aneurysmal mean static pressure did not correlate with FDS porosity or number of implanted stents.

CONCLUSION: Implantation of FDS effectively reduces aneurysm inflow in a porosity-dependent way without relevantly affecting static mean intra-aneurysmal pressure.

ABBREVIATIONS: FDS, flow-diverting stent

MAP, mean arterial pressure

PED, Pipeline Embolization Device

*University of Heidelberg, Medical Faculty Mannheim, Department of Neuroradiology, Mannheim, Germany;

University Hospital of the RWTH Aachen, Department of Diagnostic and Interventional Neuroradiology, Aachen, Germany

Correspondence: Marc A. Brockmann, MD, University Hospital of the RWTH Aachen, Department of Diagnostic and Interventional Neuroradiology, Pauwelsstrasse 30, 52074 Aachen, Germany. E-mail:

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Received February 07, 2013

Accepted November 12, 2013

Copyright © by the Congress of Neurological Surgeons