Role of Aortic Geometry on Stroke Propensity based on Simulations of Patient-Specific Models

Abstract

Stroke is a life threatening event that is expected to more than double over the next 40 years. Atrial fibrillation (AF) has been reported as a strong independent risk factor for stroke. We have previously shown that a hemodynamic perturbation by AF or reduced cardiac output and cycle length may have a significant impact on clot trajectory and thus embolic stroke propensity through the left common carotid artery using an idealized aortic arch model. Here, we show the dependence of flow patterns and hence stroke propensity on geometry of patient-specific aortas. We performed computational fluid dynamics (CFD) simulations to determine the variations of AF-induced stroke propensity over various image-based patient-dependent aorta models. The results demonstrated that curvature pattern of aorta can play a determinant role in AF-induced stroke propensity alteration. Specifically, it was shown that the hemodynamic perturbation by AF considered led to substantial increase in stroke propensity (i.e., 2.5~3.8 fold elevation) for lower curvature angle <90° while the changes in stroke propensity by AF are negligible for higher curvature angle >90°. The present simulations suggest that aortic arch curvature is an important risk factor for embolic stroke which should be tested in future clinical trials.

Distribution of Artificial Thrombi Candidates Through Patient-Specific Aortic-Arch Phantoms under Pulsatile Flow Conditions

“…In contrast to other emboli repartition studies, where AF and N owrates are used to make a distinction between stroke propensity [2], [3], our results indicate that in the presence of clots, even under normal cardiac conditions, emboli are still able to easily exit from arteries leading to the brain, in proportion to the owrate. For the Circle of Willis, Chung 6 concludes that smaller emboli are carried proportionally to the ow volume which seems to be con rmed by the present study.…”

“…The arteries discussed are the brachio-cephalic artery (BCA), the left-common-carotid artery (LCCA) and the left subclavian artery (LSA), out of which only one division branch of the BCA (the right common carotid artery) and the LCCA lead to the brain. The stroke propensity is shown to be directly linked to the diameter of the arteries in Choi's study [3] but only with the atrial brillation ow. The purpose of this study is to explore, in-vitro, such assumptions, at rst with the normal ow.…”

“…According to Malone et al [2], the embolus size is not the only responsible factor for stroke propensity as the owrate may also impact the number of emboli which can be recovered in arteries. Some computational studies of emboli dynamics are available [3], [4], [5]. Choi's study focused on the comparison between atrial brillation and normal heart ow with emboli in the size range of 2 to 6 millimeters.…”

Numerical Study of Atrial Fibrillation Effects on Flow Distribution in Aortic Circulation

“…Unlike 2D/3D CFD methods, lumped and one-dimensional approach cannot examine local variations of flow structure and associated haemodynamic metrics during AF. Therefore, employing 3D CFD approach, Choi et al 12 examined different aorta morphologies during AF-resulted strokes. The main outcome of their study emphasised that in cases with mild aortic arch (AoA) curvature, the possibility of stroke occurrence during AF increases up to three-fold comparing with the normal cardiac rhythm.…”

Class imbalance in gradient boosting classification algorithms: Application to experimental stroke data

“…Numeric simulations suggest that aortic arch curvature is an important risk factor for embolic stroke. 20 The swirling helical flow associated with vascular curvature has been shown to play a substantial role in embolus transport within the carotid artery. 21 However, our data show that, clot geometry is more important than arch geometry when analysing the hemodynamics that influence stroke occurrence.…”