Presentation Title

The Effects of Stent Shape on Intra-Aneurysmal Hemodynamics

Faculty Mentor

Masaru Rao

Start Date

18-11-2017 9:15 AM

End Date

18-11-2017 9:30 AM

Location

9-247

Session

Engineering/CS 3

Type of Presentation

Oral Talk

Subject Area

engineering_computer_science

Abstract

A brain aneurysm is a bulging of a portion of an intracranial artery which may rupture, leading to neurological deficit or death. Flow Diverting (FD) stents are used to treat aneurysms by altering the hemodynamics to slow intra-aneurysmal flow and reduce wall shear, thus reducing the risk of rupture by facilitating occlusion of the aneurysm by thrombosis (i.e. clotting). While current FD stents have shown excellent efficacy in the clinic, current reliance upon a wire-braiding based manufacturing process limits such devices to struts with circular cross sections. This, therefore, largely limits the opportunity for performance optimization to modulation of strut porosity alone (i.e. strut-to-strut spacing). The research presented herein aims to explore a potentially new means for optimizing FD stent performances by modulating strut cross section shape.

ANSYS-Fluent was used to conduct numerical studies on a 2-dimensional model of an idealized side wall wide-necked saccular aneurysm. Three strut cross section shapes were studied (square, triangle, and circle), and strut porosities were varied across a range of 0.72 to 0.94. Measurements of average velocity and wall shear stress were taken inside the aneurysm sac. Square cross section struts were observed to be the best at reducing velocity inside the aneurysm, followed by circular and triangular struts; this trend held across most porosities. These findings demonstrate that strut shape can have dramatic effects on intra-aneurysmal flow, particularly at high porosity values. This is clinically relevant, since this suggests potential for exploiting strut shape as a new means for optimizing FD performance.

Summary of research results to be presented

Different shapes, rectangle, circle, and triangle, of stent struts were studied in this research. The porosity, or spacing of each strut, varied over a range from 72% to 94%. It was observed that the rectangle shape was the best at reducing velocity inside the aneurysm then circle and triangle. This trend was seen to occur at most of the porosity values. Velocity reductions showed and inverse relationship to porosity; as porosity increased the velocity reductions decreased. This work showed the dramatic effects strut shape can have on intra-aneurysmal properties.

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Nov 18th, 9:15 AM Nov 18th, 9:30 AM

The Effects of Stent Shape on Intra-Aneurysmal Hemodynamics

9-247

A brain aneurysm is a bulging of a portion of an intracranial artery which may rupture, leading to neurological deficit or death. Flow Diverting (FD) stents are used to treat aneurysms by altering the hemodynamics to slow intra-aneurysmal flow and reduce wall shear, thus reducing the risk of rupture by facilitating occlusion of the aneurysm by thrombosis (i.e. clotting). While current FD stents have shown excellent efficacy in the clinic, current reliance upon a wire-braiding based manufacturing process limits such devices to struts with circular cross sections. This, therefore, largely limits the opportunity for performance optimization to modulation of strut porosity alone (i.e. strut-to-strut spacing). The research presented herein aims to explore a potentially new means for optimizing FD stent performances by modulating strut cross section shape.

ANSYS-Fluent was used to conduct numerical studies on a 2-dimensional model of an idealized side wall wide-necked saccular aneurysm. Three strut cross section shapes were studied (square, triangle, and circle), and strut porosities were varied across a range of 0.72 to 0.94. Measurements of average velocity and wall shear stress were taken inside the aneurysm sac. Square cross section struts were observed to be the best at reducing velocity inside the aneurysm, followed by circular and triangular struts; this trend held across most porosities. These findings demonstrate that strut shape can have dramatic effects on intra-aneurysmal flow, particularly at high porosity values. This is clinically relevant, since this suggests potential for exploiting strut shape as a new means for optimizing FD performance.