Introduction/purpose

Flow-diverting Pipeline stents are commonly used for endovascular treatment of cerebral aneurysms but can be associated with delayed ipsilateral intracerebral hemorrhage. Although intra-aneurysmal hemodynamic changes have been studied, parent vessel and intracranial hemodynamics after Pipeline stenting are unknown. Here, we examine the impact of Pipeline stenting on parent artery and distal intracranial hemodynamics.

Materials and methods

Records of patients with internal carotid cerebral aneurysms treated with Pipeline stenting at our institution were retrospectively reviewed. Patients were included if flows were obtained after stenting using quantitative magnetic resonance angiography. Flow volume rate and mean, systolic, and diastolic flow velocities were measured in the internal carotid artery (ICA, cervical segment) and middle cerebral artery (MCA, M1 segment). Pulsatility index [(systolic - diastolic flow velocity)/mean flow velocity], resistance index [(systolic - diastolic flow velocity)/systolic flow velocity], and wall shear stress (WSS) were calculated for each vessel. Means were compared between ipsilateral and contralateral ICA and MCA using two-tailed Wilcoxon signed-rank tests.

Results

Nine patients were included, mean age 51 years. All aneurysms were located in the cavernous or paraclinoid segments of the ICA. Within the parent vessel, mean flow velocity (18.1 vs. 23.4 cm/s, P = 0.04) and diastolic velocity (15.4 vs. 20.2 cm/s, P = 0.04) were significantly lower than in the contralateral ICA, and systolic velocity was also lower (20.8 vs. 26.9 cm/s, P = 0.06) but not as significantly (Figure 1A). These lower flow velocities were accompanied by higher, although non-significant, pulsatility (0.31 vs. 0.29, P = 0.93) and resistance indices (0.26 vs. 0.25, P = 0.87) and slightly lower flow (248.1 vs. 277.6 mL/min, P = 0.61) in the parent vessel. In the ipsilateral MCA, however, pulsatility (0.19 vs. 0.30, P = 0.06) and resistance indices (0.17 vs. 0.25, P = 0.04) were significantly lower, and flow higher (152.1 vs. 135.6 mL/min, P = 0.17), than in the contralateral MCA (Figure 1B). These lower resistances were accompanied by a higher trend in ipsilateral versus contralateral MCA mean flow velocity (29.9 vs. 26.8 cm/s, P = 0.37), systolic velocity (32.9 vs. 31.3 cm/s, P = 0.86), diastolic velocity (27.3 vs. 23.5 cm/s, P = 0.17), and WSS (26.8 vs. 23.9 dynes/cm², P = 0.44).

Conclusion

After Pipeline stenting, there appears to be alteration in the elasticity of the stented ICA segment, with significantly lower flow velocities in the ipsilateral versus contralateral ICA. Conversely, there was an increase in flow velocities and WSS and significantly lower resistance in the ipsilateral MCA, suggesting the possible role of altered distal hemodynamics in delayed ipsilateral hemorrhages.

Disclosures

S. Shakur: None. V. Aletich: None. S. Amin-Hanjani: None. F. Charbel: None. A. Alaraj: None.

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