Relationship between haemodynamic changes and outcomes of intracranial aneurysms after implantation of the pipeline embolisation device: a single centre study

Abstract

<jats:sec><jats:title>Background</jats:title><jats:p> Intracranial aneurysms are increasingly being treated by the placement of flow diverters; however, the factors affecting the outcome of aneurysms treated using flow diverters remain unclarified. </jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p> The present study investigated 94 aneurysms treated with pipeline embolisation device placement, and used a computational fluid dynamics method to explore the factors influencing the outcome of aneurysms. </jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p> Seventy-six completely occluded aneurysms and 18 incompletely occluded aneurysms were analysed. Before treatment, inflow jets were found in 13 (72.2%) aneurysms in the incompletely occluded group and 34 (44.7%) in the completely occluded group ( P = 0.292). After deployment of the pipeline embolisation device, inflow jets remained in nine (50%) aneurysms in the incompletely occluded group and nine (11.8%) in the completely occluded group ( P = 0.001). In the incompletely occluded group, regions with inflow jets after treatment corresponded with the patent areas shown on follow-up digital subtraction angiography. The mean reduction ratios of velocity in the whole aneurysm and on the neck plane were lower in the incompletely occluded than in the completely occluded group ( P = 0.003; P = 0.017). Multivariate analysis revealed that the only independent risk factors for incomplete aneurysm occlusion were the reduction ratios of velocity (in the whole aneurysm, threshold 0.362, P = 0.005; on the neck plane, threshold 0.273, P = 0.015). </jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p> After pipeline embolisation device placement, reduction ratios of velocity in the whole aneurysm of less than 0.362 and on the neck plane of less than 0.273 are significantly associated with a greater risk of aneurysm incomplete occlusion. In addition, the persistence of inflow jets in aneurysms is associated with incomplete occlusion in the inflow jet area. </jats:p></jats:sec>

The effect of Dean, Reynolds and Womersley numbers on the flow in a spherical cavity on a curved round pipe. Part 2. The haemodynamics of intracranial aneurysms treated with flow-diverting stents

“…Image-based computational studies have linked the post-treatment haemodynamics environment to treatment outcomes, suggesting that a threshold of reduction of stresses or flow velocities inside the aneurysm exists and must be surpassed for successful aneurysm embolization to occur (Kulcsár et al 2012;Mut et al 2015;Paliwal et al 2017). Most recently an in vivo study using four-dimensional magnetic resonance imaging (Su et al 2020) and an image-based computational fluid dynamics study (Chen et al 2019) separately linked FDS treatment failure with the existence of a strong inflow jet into the aneurysm sac.…”

“…Since then, a number of studies (Cantón et al 2005a,b;Babiker et al 2012;Rayepalli et al 2013;Damiano et al 2015) have investigated the influence of the stent properties on aneurysmal flow reduction, attempting to determine the ideal porosity, placement location and number of stents for aneurysm flow reduction. Additionally, in recent years, much research has been focused on developing a causal relationship between reduction in aneurysm haemodynamics following FDS deployment and treatment outcome (Kulcsár et al 2012;McAuliffe et al 2012;Paliwal et al 2017;Chen et al 2019;Su et al 2020). These studies have all compared changes in pre-and post-treatment aneurysm haemodynamics in patient-specific computational fluid dynamics simulations with a patient's treatment outcome and suggested candidate thresholds in fluid mechanics variables, such as intra-aneurysmal velocity reduction, that could be predictive of successful treatment.…”

The effect of Dean, Reynolds and Womersley numbers on the flow in a spherical cavity on a curved round pipe. Part 1. Fluid mechanics in the cavity as a canonical flow representing intracranial aneurysms

“…an increased flow impingement). This important impinging jet entering the cavity, which becomes more important with the curvature of the parent vessel, has been found to impact the outcomes of treatment with flow diverters (Chen et al 2019;Su et al 2020). Hence, aneurysms attached to a vessel with high curvature may be more likely to fail when being treated with diverters.…”

“…Understanding the fluid dynamics at the neck and inside the sac of intracranial aneurysms, and its dependence on anatomical and physiological parameters that change from case to case, is essential to quantify the changes in haemodynamics introduced by endovascular treatment, and in particular by flow diverting stents (Fukuda et al 2019;Texakalidis et al 2019;Wan et al 2019). Flow patterns such as strong inflow jets in the aneurysmal sac have been found to be detrimental to treatment with flow diverters (Chen et al 2019;Su et al 2020), whose goal is the formation of a stable thrombus for successful treatment (Rajah, Narayanan & Rangel-Castilla 2017). These studies provide evidence that the haemodynamics has a controlling effect on thrombosis through the Lagrangian residence time of platelets and the Eulerian wall shear stress (WSS) on endothelial cells (Ngoepe et al 2018).…”

“…Flow patterns such as strong inflow jets in the aneurysmal sac have been found to be detrimental to treatment with flow diverters (Chen et al. 2019; Su et al. 2020), whose goal is the formation of a stable thrombus for successful treatment (Rajah, Narayanan & Rangel-Castilla 2017).…”