In vitro evaluation of the influence of flow divertors on intra-aneurysmal flow

The objective of endovascular treatment of cerebral aneurysm is to exclude them from the circulation. Flow divertors, which are stent-like devices, can serve as adjunct to coils or stand alone bioimplants for treatment of cerebral aneurysms. Currently only few stents are available for treatment in the cerebrovasculature, however these have been designed as scaffolds for coiling. Thus, to successfully exclude an aneurysm from the circulation, the design parameters of the flow diverter, such as porosity and pore density (or filament diameter), have to be tailored to the local hemodynamics for long term success of the treatment.This study investigates the influence of flow divertor implantation on intra-aneurysmal flow. The divertors were placed in the parent artery traversing the neck of the aneurysm. The experimental in vitro aneurysm was molded of a compliant silicone elastomer and is a replica of an elastase-induced saccular aneurysm model in rabbit. The elastase-induced saccular aneurysm in the rabbit right common carotid artery was developed as a model of a human cerebrovascular aneurysm. It is currently used for testing various endovascular devices and therapies because the morphology of the experimental in vivo aneurysm is similar to that of the human ophthalmic artery aneurysm in brain.The results show that flow divertors significantly reduce flow activity inside the aneurysm. After flow divertors were implanted in the silicone model, the mean hydrodynamic circulation inside the aneurysm was reduced to about 14% of its pre-divertor value, and wall shear oscillation was also reduced inside the aneurysm. Therefore, flow divertors can induce sufficient flow stasis inside the aneurysm and possibly trigger spontaneous thrombosis