<i>In vitro</i> hydrodynamical study on parent vessel curvature for treating intracranial aneurysms using particle imaging velocimetry

Abstract

We have developed a micro-porous covered stent (NCVC-CS1) for intracranial aneurysm (IA) treatment. Thrombus formation is locally promoted by flow diversion or isolation in the target IA after stenting, and the IA can be embolised. Despite using the same stent in clinical practice, the therapeutic effect may not be the same because the size and morphology of the IA and the parent vessel flow affect IA flow. Therefore, this study clarifies the influence of flow in a curved parent vessel on the flow diversion/isolation performance of the low-porosity stent using particle imaging velocimetry (PIV). In vitro experiments were conducted under steady flow conditions based on a flow similarity law using a two-dimensional parent vessel model with a saccular IA, a U-shaped parent vessel, and a simplified micro-porous film model. The results indicated that the area mean shear rate was well expressed by a power function using the Dean number. The cross-flow velocity component's root mean square (RMS) perpendicular to the IA neck increased with a sharply curved vessel. In particular, when the curvature-radius ratio was larger than 1/2, the RMS of the cross-flow velocity remarkably increased despite stenting, suggesting that the stenting performance in a sharper-curved vessel is significantly affected.