Design optimization for thin film based flow diverter stents for the treatment of intracranial aneurysms
Prasanth Velvaluri1, Mariya Pravdivtseva2, Rodrigo Lima de Miranda3, Olav Jansen2, Eckhard Quandt1
1Chair for Inorganic Functional Materials, Faculty of engineering, Kiel University, Germany.
2Department of Radiology and Neuroradiology, Kiel University Hospital, Germany.
3AQUANDAS GmbH, Kiel, Germany.
Currently, Flow Diverter Stents (FDS) are one of the most often used devices in the treatment of intracranial aneurysms. The function of such a stent is to steer the blood flow away from an aneurysm and to promote endothelialization at the neck of an aneurysm. Sputtered thin film based FDS have a lot of potential because of their possible complex design structures, miniaturization  and an added ability to tailor the mechanical properties including fatigue  compared to their commercial (conventional) counter parts.
However, certain criteria like stress evolution during crimping and radial force on vessel wall after deployment, as it plays a key role in FDS functionality. Design of the stent is an important factor for these criteria and it is not practical to test all the combinations; a better way of evaluating is the optimization of design parameters by using finite element method (FEM). In the present study, we have used Abaqus for understanding the crimping of the stent by considering a non - linear material model.
Furthermore, the produced stent has be evaluated for flow diversion using 4D flow MRI (3T, Philips) by deploying them in 3D printed patient specific aneurysm models. We present the 3D material model validation along with a routine to investigate the crimpability to evaluate an optimal stent design parameters. We also discuss the experimental characterization of the produced stents through mechanical and flow testing.