Effects of framing coil shape, orientation, and thickness on intra-aneurysmal flow

To study the effects of the geometrical characteristics of a framing coil on aneurysm thromboembolization efficacy, the hemodynamics in lateral aneurysms filled with coils having a different shape, orientation, and thickness were analyzed using computational fluid dynamics. The aneurysms packed with vortex and cage-shaped coils were modeled using three different coil orientations: transverse, parallel, and orthogonal. The orthogonal orientation of a vortex coil and parallel orientation of a cage-shaped coil showed higher inflow, vorticity, and wall shear stress in the dome region, which provide an unfavorable hemodynamic environment for thromboembolization. Thicker coils also produced unfavorable hemodynamic conditions compared to normal coils having the same shape, orientation, and total coil volume. Though the effects of coil shape and orientation on the hemodynamic parameters of interest were not consistent, the open area at the distal half of the mid-transverse plane of an aneurysm showed significant positive correlation with flow into the dome region and mean vorticity in the dome region. Therefore, blocking the distal mid-transverse plane of an aneurysm using coils would effectively reduce the intra-aneurysmal flow activity and provide a more efficient hemodynamic environment for thromboembolization.