Abstract
BackgroundFlow-diverting stents are increasingly used for the minimally-invasive treatment of intracranial aneurysms. However, a correct positioning of such devices can be challenging due to varying vessel diameters as well as the complex anatomy of the neurovasculature. As a consequence, unsuccessful treatment outcomes are increasingly reported requiring an improvement of the understanding of stent-induced flow modification.MethodsTo evaluate the effect of different degrees of flow diverter stent malposition on intra-aneurysmal hemodynamic changes, a controlled hemodynamic configuration was created using an idealized intracranial aneurysms model. Afterwards, four different treatment scenarios were reproduced comprising of 1) the ideal treatment, 2) an insufficient wall apposition in the region of the ostium, 3) a distorted device migrating into the aneurysm sac and 4) an inaccurately deployed stent due to wrong release location. For the assessment of the individual flow modifications, high-resolution stereoscopic particle image velocimetry (PIV) measurements were carried out.ResultsThe analysis of the precise in-vitro PIV measurements reveals that in all cases a considerable reduction of the cycle-averaged and peak-systolic velocity was obtained. Compared to the untreated aneurysm configuration, the flow reduction ranged from 63% (scenario 4) up to 89% (scenario 3). The ideal treatment reached a reduction of 78%, which is known to be sufficient for a successful therapy. However, inaccurate device positioning leads to increased oscillating flow towards the lateral directions reducing the chances of sufficient thrombus formation.ConclusionsHigh-resolution in-vitro PIV measurements enable an accurate quantification of the treatment efficacy for flow-diverting devices. Furthermore, insufficient treatment outcomes can be reproduces allowing for an assessment of intra-aneurysmal hemodynamic changes.
Highlights
Intracranial aneurysms (IAs) are permanent dilatations of the cerebral vessel wall and rupture can lead to severe consequences such as sudden death or irreversible disabilities
Compared to the untreated aneurysm configuration, the flow reduction ranged from 63% up to 89%
Insufficient treatment outcomes can be reproduces allowing for an assessment of intra-aneurysmal hemodynamic changes
Summary
Intracranial aneurysms (IAs) are permanent dilatations of the cerebral vessel wall and rupture can lead to severe consequences such as sudden death or irreversible disabilities. Due to interventional risks as well as long recovery periods, minimally-invasive treatment techniques were invented. In this regard, platinum coils were introduced into the aneurysm sac using a microcatheter [3–5]. The placement of coils can lead to insufficient coverage of complexly shaped aneurysms or even inter-procedural perforation of thin aneurysm walls. Flow-diverting (FD) devices were developed, which are densely-braided stents that dampen the flow into the aneurysm. Flow-diverting stents are increasingly used for the minimally-invasive treatment of intracranial aneurysms. Unsuccessful treatment outcomes are increasingly reported requiring an improvement of the understanding of stent-induced flow modification
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