Flow diversion treatment: intra-aneurismal blood flow velocity and WSS reduction are parameters to predict aneurysm thrombosis

Abstract

Background To evaluate the haemodynamic changes induced by flow diversion treatment in cerebral aneurysms, resulting in thrombosis or persisting aneurysm patency over time. Method Eight patients with aneurysms at the paraophthalmic segment of the internal carotid artery were treated by flow diversion only. The clinical follow-up ranged between 6 days and 12 months. Computational fluid dynamics (CFD) analysis of pre-and post-treatment conditions was performed in all cases. True geometric models of the flow diverter were created and placed over the neck of the aneurysms by using a virtual stent-deployment technique, and the device was simulated as a true physical barrier. Pre-and post-treatment haemodynamics were compared, including mean and maximal velocities, wall-shear stress (WSS) and intra-aneurysmal flow patterns. The CFD study results were then correlated to angiographic follow-up studies.

In vitro investigation of contrast flow jet timing in patient-specific intracranial aneurysms

“…Based on our findings, the high injection rates used previously in other studies (1.5-2 mL/s) explored only the diastolic flow for the ICA aneurysms (11,14). The systolic flow jet that contributes to elevation of wall shear stress (19) and is responsible for flow impingement has been ignored in the DSA. Flow diversion affects systolic and diastolic flows differently; the diastolic flow jet is affected by deployment of a FD, but the systolic flow jet is not amenable to FD due to its strong inertia.…”

“…Effect of flow diversion is currently assessed by presence of contrast stasis or change of flow pattern (10,11,19); however, they have not been very reliable in our clinical experience. Our study quantifies the timing of flow jet by imaging aneurysm phantom and flow pump together and shows that both contrast stasis and change of flow jet are injection rate dependent.…”

Virtual-versus-Real Implantation of Flow Diverters: Clinical Potential and Influence of Vascular Geometry

“…Finally, our method also provides crucial information such as the filament location and neck porosity for further hemodynamic evaluation with computational fluid dynamics simulations. [13][14][15][16] …”

“…Furthermore, hemodynamic simulations have shown high potential in predicting intracranial aneurysm thrombosis. [14][15][16] These hemodynamic simulations require reliable and fast virtual stentdeployment methodologies. Therefore, we have recently proposed 17 a virtual stent-deployment method able to predict the local properties of braided stents (wire location, angles, porosities) and implantation parameters (stent length, landing zone) with minimal computational cost.…”

Editorial: Flow diverters: one device does not fit all

“…This was based on data from 131 patients studied between 2007 and 2009. 1,5 The indication for use was for large or giant, wide-necked aneurysms of the internal carotid artery (ICA) in patients older than 22 years. Use has expanded widely beyond this, with spectacular results in some of these off-label indications.…”