In Vitro Investigation of a New Thin Film Nitinol-Based Neurovascular Flow Diverter

Autor: Breigh N. Roszelle, W. Hafner, L. F. Gonzalez, Youngjae Chun, Colin Kealey, David H. Frakes, Felipe C. Albuquerque, Daniel S. Levi, H. Y. Farsani, Gregory P. Carman, M. H. Babiker
Rok vydání: 2016
Předmět:
Zdroj: Journal of Medical Devices. 10
ISSN: 1932-619X
1932-6181
DOI: 10.1115/1.4033015
Popis: Fusiform and wide-neck cerebral aneurysms can be challenging to treat with conventional endovascular or surgical procedures. Recently, flow diverters have been developed that treat such aneurysms by diverting flow away from the sac rather than direct occlusion. The Pipeline Embolization Device (PED), which embodies a single-layer braided design, is best known among available flow diverters. While the device has demonstrated success in recent trials, late aneurysmal rupture after PED treatment has been a concern. More recently, a new generation of dual-layer devices has emerged that includes a novel Hyperelastic Thin Film Nitinol (HE-TFN)-covered design. In this study, we compare fluid dynamic performance between the PED and HE-TFN devices using particle image velocimetry (PIV). The PED has a pore density of 12.5-20 pores/mm2 and a porosity of 65-70%. The two HE-TFN flow diverters have pore densities of 14.75 pores/mm2 and 40 pores/mm2, and porosities of 82% and 77%, respectively. Conventional wisdom suggests that the lower porosity PED would decrease intraaneurysmal flow to the greatest degree. However, under physiologically realistic pulsatile flow conditions, average drops in root-mean-square velocity (VRMS) within the aneurysm of an idealized physical flow model were 42.8-73.7% for the PED and 68.9-82.7% for the HE-TFN device with the highest pore density. Interestingly, examination of collateral vessel flows in the same model also showed that the HE-TFN design allowed for greater collateral perfusion than the PED. Similar trends were observed under steady flow conditions in the idealized model. In a more clinically realistic scenario wherein an anatomical aneurysm model was investigated, the PED affected intraaneurysmal VRMS reductions of 64.3% and 56.3% under steady and pulsatile flow conditions, respectively. In comparison, the high pore density HE-TFN device reduced intraaneurysmal VRMS by 88% and 71.3% under steady and pulsatile flow conditions, respectively. The HE-TFN device also led to greater reductions in cross-neck flow than the PED. We attribute the superior performance of the HE-TFN device to higher pore density, which may play a more important role in modifying aneurysmal fluid dynamics than the conventional flow diverter design parameter of greatest general interest, absolute porosity. Lastly, the PED led to more elevated intraaneurysmal pressures after deployment, which provides insight into a potential mechanism for late rupture following treatment with the device.
Databáze: OpenAIRE
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