Angular remodeling in single stent-assisted coiling displaces and attenuates the flow impingement zone at the neck of intracranial bifurcation aneurysms.

BACKGROUND Self-expanding intracranial stent-assisted coiling of bifurcation aneurysms has recently been shown to straighten target cerebral vessels, a phenomenon with unknown hemodynamic effect. OBJECTIVE To investigate the impact of angular remodeling in aneurysms treated with single stent-assisted coiling with the use of computational fluid dynamic techniques. METHODS Fourteen patients (7 women, mean age 55) who underwent stent coiling of 14 wide-necked bifurcation aneurysms were included based on the availability of high-resolution 3-dimensional rotational angiography. Pretreatment data sets underwent virtual aneurysm removal to isolate the effect of stenting. Wall shear stress and pressure profiles obtained from constant flow input computational fluid dynamic analysis were analyzed for apical hemodynamic changes. RESULTS Stenting increased the bifurcation angle with significant straightening immediately after treatment and at follow-up (107.3° vs. 144.9°, P < .001). The increased stented angle at follow-up led to decreased pressure drop at the bifurcation apex (12.2 vs. 9.9 Pa, P < .003) and migration of the flow impingement zone (FIZ) toward the contralateral nonstented daughter branch by a mean of 1.48 ± 0.2 mm. Stent-induced angular remodeling decreased FIZ width separating peak apical wall shear stress (3.4 vs. 2.5 mm, P < .004). Analysis of FIZ distance measured from the parent vessel centerline showed it to be linearly (r = .58, P < .002) and FIZ width inversely correlated (r = .46, P < .02) to vessel bifurcation angle. CONCLUSION Stent-induced angular remodeling significantly altered bifurcation apex hemodynamics in a favorable direction by blunting apical pressure and inducing the narrowing and migration of the FIZ, a novel response to intracranial stenting that should be added to intimal hyperplasia and flow diversion.