Hemodynamic Investigation of the Effectiveness of a Two Overlapping Flow Diverter Configuration for Cerebral Aneurysm Treatment.

Yuya Uchiyama,Hiroyuki Takao,Soichiro Fujimura,Koji Fukudome,Yuichi Murayama,Makoto Yamamoto,Takashi Suzuki,Toshihiro Ishibashi,Motoharu Hayakawa,Kostadin Karagiozov

doi:10.3390/bioengineering8100143

Yuya Uchiyama, Hiroyuki Takao + Show 8 more

Open Access

https://doi.org/10.3390/bioengineering8100143

Copy DOI

Abstract

Flow diverters (FDs) are widely employed as endovascular treatment devices for large or wide-neck cerebral aneurysms. Occasionally, overlapped FDs are deployed to enhance the flow diversion effect. In this study, we investigated the hemodynamics of overlapping FDs via computational fluid dynamics (CFD) simulations. We reproduced the arterial geometry of a patient who had experienced the deployment of two overlapping FDs. We utilized two stent patterns, namely the patterns for one FD and two overlapping FDs. We calculated the velocity, mass flow rate, wall shear stress, and pressure loss coefficient as well as their change rates for each pattern relative to the no-FD pattern results. The CFD simulation results indicated that the characteristics of the blood flow inside the aneurysm were minimally affected by the deployment of a single FD; in contrast, the overlapping FD pattern results revealed significant changes in the flow. Further, the velocity at an inspection plane within the aneurysm sac decreased by up to 92.2% and 31.0% in the cases of the overlapping and single FD patterns, respectively, relative to the no-FD pattern. The simulations successfully reproduced the hemodynamics, and the qualitative and quantitative investigations are meaningful with regard to the clinical outcomes of overlapped FD deployment.

Highlights

Cerebral aneurysm is a common cerebrovascular condition in which part of the cerebral artery deforms
Flow diverters (FDs) are useful for treating complex aneurysms, the degree of blood flow reduction is not always sufficient to allow thrombosis formation
Because the blood flow entered the aneurysmal sac in the lateral direction and flowed along the aneurysm wall in the cases of the non-stent and the single patterns, the wall shear stress (WSS) was relatively high near the bottom of the aneurysmal sac

Summary

Introduction

Cerebral aneurysm is a common cerebrovascular condition in which part of the cerebral artery deforms. The frequency of the cerebral aneurysms has been reported to be approximately 1–10% for the total population [1,2,3]. Endovascular treatment methods are widely employed to treat cerebral aneurysms because they are minimally invasive. Flow diverters (FDs) were originally developed as endovascular treatment devices; they have been designed to treat large-, giant-, and wide-neck aneurysms because of their relatively high rupture risks and the difficulty of treatment via conventional endovascular coiling techniques [1,4]. FDs are useful for treating complex aneurysms, the degree of blood flow reduction is not always sufficient to allow thrombosis formation

Methods

Results

Discussion

Conclusion