Measurement of flow diverter hydraulic resistance to model flow modification in and around intracranial aneurysms

Flow diverters (FDs) have been successfully applied in the recent decade to the treatment of intracranial aneurysms by impairing the communication between the flows in the parent artery and the aneurysm and, thus, the blood within the aneurysm sac. It would be desirable to have a simple and accurate computational method to follow the changes in the peri- and intraaneurysmal flow caused by the presence of FDs. The detailed flow simulation around the intricate wire structure of the FDs has three disadvantages: need for high amount of computational resources and highly skilled professionals to prepare the computational grid, and also the lack of validation that makes the invested effort questionable. In this paper, we propose a porous layer method to model the hydraulic resistance (HR) of one or several layers of the FDs. The basis of this proposal is twofold: first, from an application point of view, the only interesting parameter regarding the function of the FD is its HR; second, we have developed a method to measure the HR with a simple apparatus. We present the results of these measurements and demonstrate their utility in numerical simulations of patient-specific aneurysm simulations

Computation of the change in length of a braided device when deployed in realistic vessel models

Purpose An important issue in the deployment of braided stents, such as flow diverters, is the change in length, also known as foreshortening, underwent by the device when is released from the catheter into a blood vessel. The position of the distal end is controlled by the interventionist, but know- ing a priori the position of the proximal end of the device is not trivial. In this work, we assess and validate a novel computer method to predict the length that a braided stent will adopt inside a silicon model of an anatomically accurate vessel. Methods Three-dimensional rotational angiography images of aneurysmatic patients were used to generate surface mod- els of the vessels(3Dmeshes) and then create accurate silicon models from them. A braided stent was deployed into each silicon model to measure its length.Thesamestents deployed on the silicon models were virtually deployed on the 3D meshes using the method being evaluated. Results The method was applied to five stent placements on three different silicon models. The length adopted by the real braided device in the silicon models varies between 15 and 30%from the stent length specified by the manufacturer. The final length predicted by themethodwaswithin the esti- mated error of the measured real stent length.Conclusions The method provides, in a few seconds, the length of a braided stent deployed inside a vessel, showing an accurate estimation of the final length for the cases studied. This technique could provide useful information for plan- ning the intervention and improve endovascular treatment of intracranial aneurysms in the future.Fil: Fernandez, Hector. Galgo Medical S.L.; EspañaFil: Macho, Juan M.. Hospital Clinic Provincial de Barcelona; EspañaFil: Blasco, Jordi. Hospital Clinic Provincial de Barcelona; EspañaFil: San Roman, Luis. Hospital Clinic Provincial de Barcelona; EspañaFil: Mailaender, Werner. Acandis GmbH; AlemaniaFil: Serra, Luis. Galgo Medical S.L.; EspañaFil: Larrabide, Ignacio. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Grupo de Plasmas Densos Magnetizados. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Grupo de Plasmas Densos Magnetizados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; Argentin