Vascular Geometry Change Because of Endovascular Stent Placement for Anterior Communicating Artery Aneurysms

BACKGROUND AND PURPOSE: Hemodynamics have been shown to play an important role in the initiation and progress of intracranial aneurysms, and are considered well-related to vascular configuration. The purpose of this study was to quantify the vascular geometry change due to intracranial stent placement and to discuss its potential effects on hemodynamics. MATERIALS AND METHODS: Imaging data of patients with wide-neck AcomA aneurysms, treated with stent-assisted coiling between January 2005 and January 2010, were retrospectively analyzed. The angle between the afferent vessels (A1 segment) and the efferent vessels (ipsilateral or contralateral A2 segment) was calculated to determine the exact change in the angle after stent placement. RESULTS: In all 20 patients, the stent caused a distinct change in the geometry of the parent vessel. Stent-related vascular angle change ranged from 7.60 to 74.88 degrees, with an average of 29.95 degrees. In 10 cases, the angle changed by >30 degrees. In the 12 patients with the distal segment of the stent placed in the ipsilateral A2 segment, the mean postoperative A1-A2 angle increased by 27.71 +/- 13.17 (from 7.60 degrees to 48.29 degrees). In the other 8 patients with the distal segment of the stent placed in the contralateral A2 segment, the mean postoperative A1-AcomA-A2 angle increased by 33.29 +/- 21.89 degrees (from 15.49 degrees to 74.88 degrees). CONCLUSIONS: In addition to serving as a scaffold to contain coils, stent placement for AcomA aneurysms has a substantial effect on the vascular geometry, which may result in local hemodynamic changes.