Endovascular treatment of fusiform aneurysms with stents and coils: technical feasibility in a swine model.

PURPOSE

To assess the biomechanical feasibility of treating experimental fusiform aneurysms endovascularly with a combination of stents and coils.

METHODS

An experimental model was surgically constructed in the necks of nine swine to simulate intracranial fusiform aneurysms possessing important "perforators" or side branches. Balloon-expandable metal stents were positioned across the aneurysms in eight swine. In five of these, additional treatment was intraaneurysmal placement of detachable microcoils. Attempts were made to deposit these coils strategically away from the origin of the side branch.

RESULTS

Stent placement was successful in seven swine but failed in one swine because of stent-aneurysm size mismatch. Two swine treated with only stents showed no significant alterations in blood filling of the aneurysm or side branch. Satisfactory coil placement (outside the stent, within the aneurysm sac, and away from the orifice of the side branch) was achieved in four of the five swine treated with stents and coils. Careful fluoroscopic monitoring and controlled coil delivery were necessary to avoid covering the sidebranch origin. These aneurysms could not be packed densely after detachment of the first coil because of the resultant radiographic overlap of multiple coil loops on the stent and its lumen in all projections. In one swine there was inadvertent untoward reentry of the coil tip into the expanded stent lumen during its delivery.

CONCLUSION

Endovascular treatment of experimental fusiforms aneurysms using stents and coils is technically feasible. The stent maintains patency of the parent artery while allowing strategic coil placement in the aneurysm sac away from the origin of side branches. This technique may prove useful in the future treatment of intracranial fusiform aneurysms. However, potential sources of technical difficulties have been identified, and further longterm studies using an appropriate intracranial stent will be necessary before human application.