In vitro studies for stent-assisted coiling of terminus aneurysms by straight-on intra-aneurysmal stent deployment

Deployment of a Neuroform microstent (NFM; Boston Scientific/Target, Freemont, California, USA) within acutely angled geometry may result in substantial deformations. This in vitro study was conducted to validate a novel alternative technique, consisting of intentional deployment of a NFM straight on into a terminus aneurysm, by assessing the mechanics, feasibility, and stability of the coils.

Silicon models of wide-neck terminus aneurysms were constructed. Straight-on deployment of a NFM from the afferent vessel into the aneurysm was compared with conventional cross-neck deployment at a right angle position followed by Guglielmi detachable coil embolization simulation. The supporting forces of the two different methods of deployment were compared by the use of side-wall eccentric and en-face compression tests.

Straight-on deployment of a NFM at a wide-neck terminus aneurysm was a relatively simple technique compared with cross-neck right angle deployment. Good stability of the coil mass was consistently achieved with adequate preservation of the parent vessel lumen. A larger residual neck space at the side without the stent and much coil mass protruding into the parent vessel were observed in cross-neck stent deployment. Compression tests revealed a larger supporting force of the NFM with straight-on deployment compared with the side-wall radial force (P < 0.05). A potential problem with this technique is the possible inability or difficulty in retrieving a partially deployed coil.

Stent-assisted coiling of wide-neck terminus aneurysms with straight-on deployment of NFM consistently achieved a stable NFM-coil complex. The NFM also had a better supporting force in a straight position. Some technical difficulties may be encountered during subsequent coiling. This alternative technique to conventional cross-neck bridging appears to be another strategy for wide-neck terminus aneurysm coiling.