The impact of stent strut porosity on reducing flow in cerebral aneurysms.

BACKGROUND AND PURPOSE

Flow diversion techniques are increasingly used to treat cerebral aneurysms. The optimal stent porosity to achieve aneurysm obliteration would allow clinicians to treat aneurysms more effectively. We sought to determine the optimal porosity threshold in an in vitro flow model that would lead to stagnation of flow in an aneurysm.

METHODS

Using a 3-dimensional (3-D) sidewall aneurysm glass model and a 2-dimensional (2-D) cavity model, we measured the total kinetic energy (TKE) in the cavity and aneurysm using digital particle image velocimetry by adjusting for the surface area of a metal mesh across the cavity. Additionally, we assessed how a gap between the mesh and 2-D cavity impacted circulatory patterns within a cavity.

RESULTS

In the 3-D aneurysm model, we noted a 90.4% reduction in TKE after placement of a stent. In the 2-D cavity model, we adjusted the porosity between 39.1% and 64.8% and noted a reduction in the TKE by 99.75% and 93.9%, respectively. When there was a gap between the mesh and entry into the cavity, unfavorable circulatory conditions occurred with the development of counterclockwise flow that had increased TKE within the cavity.

CONCLUSIONS

The current model demonstrates a method to evaluate the optimal porosity threshold to achieve thrombosis of an aneurysm as a primary modality. Moreover, a gap may occur between the stent and the aneurysm that may create unfavorable circulatory conditions by increasing flow into the aneurysm.