Effect of Proximal Parent Artery Stenosis on the Outcomes of Posterior Communicating Artery Aneurysms: A Preliminary Study Based on Case-Specific Hemodynamic Analysis

OBJECTIVE: The objective of the study was to evaluate the effect of proximal parent artery stenosis on the hemodynamics of aneurysms in the internal carotid artery- posterior communicating artery (ICA-Pcom). METHODS: A retrospective study of 74 patients with aneurysms in the ICA-Pcom who underwent treatment at the Department of Neurosurgery of Changhai Hospital was conducted between January and June 2018. Patients with proximal parent artery stenosis were included. Case-specific three-dimensional images were reconstructed, and software-based simulations of different stenosis morphologies were performed, focusing on stenosis severity and the distance from the aneurysm to the stenosis. The wall shear stress (WSS) of the aneurysms and blood flow velocity of the aneurysm neck plane were calculated. We performed simulations to evaluate the outcomes of post-balloon angioplasty by considering a virtual operation group. To further assess whether WSS after balloon angioplasty increases the risk of aneurysm rupture, a control group of ruptured ICA-Pcom aneurysms without parent artery stenosis was matched with the virtual operation group based on sex, age, history of hypertension, and aneurysm size. Thereafter, the normalized WSS of the 2 groups was calculated. RESULTS: Eight patients with parent artery stenosis were included (2 men and 6 women; average age: 64 +/- 15 years). The patients were divided into eccentric and concentric stenosis groups according to the stenotic morphologies, with 4 patients in each group. In both groups, the average WSS of the aneurysm and average blood flow velocity at the neck plane increased with the severity of parent artery stenosis, whereas the WSS did not correlate with distance. In the concentric stenosis group, the average blood flow velocity generally decreased as the distance between stenosis and aneurysm increased; however, no such trend was observed in the eccentric stenosis group. The normalized WSS of aneurysms after virtual balloon angioplasty was higher than that of the ruptured aneurysms (0.599 [0.548, 0.800] vs. 0.367 [0.324, 0.407]; P = 0.007). CONCLUSIONS: Intensified severity of proximal stenosis increases the blood flow velocity and aneurysmal WSS, which may lead to the progression of ICA-Pcom aneurysms. Treatment of the stenosis can reduce the WSS of aneurysms; however, its effect on the prognosis of ICA-Pcom aneurysms requires more concrete evidence.