Introduction: Flow diversion via Pipeline Embolization Device (PED) represents the most recent advancement in endovascular therapy of intracranial aneurysms. However, the exact mechanism by which flow diversion leads to aneurysm thrombosis remains unclear. This study explores the intra-aneurysmal hemodynamic changes after PED placement and their relationship with aneurysm occlusion.
Methods: In this proof of concept study, a digital PED stent, along with its mechanical deployment process in silico, was recapitulated using our recently developed high fidelity virtual stenting algorithm. The virtual PEDs were applied to aneurysm models constructed from rotational angiography of 3 patients who were treated in real-life with PEDs. Pre- and post-treatment aneurysmal hemodynamics were analyzed using computational fluid dynamics (CFD) simulation. Flow-stasis parameters were correlated with the clinical outcome of aneurysm occlusion.
Results: Virtual PED stents were successfully generated for 3 patients with complex intracranial aneurysms who were treated with PEDs in real-life. The mean age at time of surgery was 58.7 years and 2 were female. The average aneurysm size was 10.7 mm, including a vertebral artery dissecting aneurysm, a giant supraclinoid internal carotid artery (ICA) aneurysm, and two tandem aneurysms at ICA ophthalmic segment. Two patients were treated with 1 PED and the other with giant ICA aneurysm had 2 PEDs. CFD simulation with virtual stent demonstrated that each PED placement resulted in 54.3% reduction of average wall shear stress (WSS) and 40.5% reduction of aneurysm inflow rate. Hemodynamic changes from each PED is highly variable, with decrease in WSS ranging between 27.3% and 84.4% among different aneurysms. Three aneurysms were completely occluded after 6 months, all of which had greater than 50% and 30% reduction in WSS and inflow rate, respectively.
Conclusions: In this proof of concept study, we demonstrated that a virtual PED stent can be combined with CFD analyses in patient-specific aneurysm models to estimate intra-aneurysmal hemodynamic changes after each PED deployment. Reduction in wall shear stress and inflow rate can be correlated with aneurysm occlusion.
Patient Care: Understanding the hemodynamic changes induced by PED can help decipher the mechanism by which PED leads to aneurysm thrombosis, and further clarify the indication of flow diversion for the treatment of intracranial aneurysms.
Learning Objectives: To understand hemodynamic alternations after PED deployment contributes significantly to aneurysm thrombosis in long-term.