Effects of Pulsatile Flow Rate and Shunt Ratio in Bifurcated Distal Arteries on Hemodynamic Characteristics Involved in Two Patient-Specific Internal Carotid Artery Sidewall Aneurysms: A Numerical Study

Abstract

The pulsatile flow rate (PFR) in the cerebral artery system and shunt ratios in bifurcated arteries are two patient-specific parameters that may affect the hemodynamic characteristics in the pathobiology of cerebral aneurysms, which needs to be identified comprehensively. Accordingly, a systematic study was employed to study the effects of pulsatile flow rate (i.e., PFR−I, PFR−II, and PFR−III) and shunt ratio (i.e., 75:25 and 64:36) in bifurcated distal arteries, and transient cardiac pulsatile waveform on hemodynamic patterns in two internal carotid artery sidewall aneurysm models using computational fluid dynamics (CFD) modeling. Numerical results indicate that larger PFRs can cause higher wall shear stress (WSS) in some local regions of the aneurysmal dome that may increase the probability of small/secondary aneurysm generation than under smaller PFRs. The low WSS and relatively high oscillatory shear index (OSI) could appear under a smaller PFR, increasing the potential risk of aneurysmal sac growth and rupture. However, the variances in PFRs and bifurcated shunt ratios have rare impacts on the time-average pressure (TAP) distributions on the aneurysmal sac, although a higher PFR can contribute more to the pressure increase in the ICASA−1 dome due to the relatively stronger impingement by the redirected bloodstream than in ICASA−2. CFD simulations also show that the variances of shunt ratios in bifurcated distal arteries have rare impacts on the hemodynamic characteristics in the sacs, mainly because the bifurcated location is not close enough to the sac in present models. Furthermore, it has been found that the vortex location plays a major role in the temporal and spatial distribution of the WSS on the luminal wall, varying significantly with the cardiac period.

Developing an in vitro validated 3D in silico internal carotid artery sidewall aneurysm model

“…In the ICASA model, the blood flows in through the ICA and flows out from the bifurcated distal arteries, i.e., ICA distal and posterior communicating artery (PComA). Poly-hexcore meshing strategies were adopted to generate meshes for the ICASA model using ANSYS Fluent Meshing 2021 R2 (Ansys Inc., Canonsburg, PA, United States), and the mesh independence sensitivity was investigated and reported in the previous publication ( Yi et al, 2022a ). The final mesh has 2,741,603 elements with 25 prism layers, 3 peel layers, and size growth rate 1.05.…”

“…Over past decades, many review publications summarized the efforts in studying hemodynamic factors on the pathophysiology of CAs, including varying risks associated with aneurysmal sac locations, high risk aneurysm morphologies, pre- and post-treatment states, and arterial blood flow conditions in vivo , in vitro , and in silico ( Sforza et al, 2009b ; Nieuwkamp et al, 2009 ; Nixon et al, 2010 ; Aoki and Nishimura, 2011 ; Jeong and Rhee, 2012 ; Fennell et al, 2016 ; Sheikh et al, 2020 ; Yu et al, 2021 ; Yi et al, 2022a ). Although transcranial Doppler velocimetry (TDV), as a non-invasive in vivo manner, can be used to assess cerebral mean blood flow velocity in the cerebral arteries ( Aaslid et al, 1982 ; Hart and Haluszkiewicz, 2000 ; Conde-Agudelo et al, 2015 ), this approach can only obtain values in limited local regions of the cerebral arteries rather than a thorough blood flow distribution in the arteries.…”

Evaluation of hemodynamic effects of different inferior vena cava filter heads using computational fluid dynamics

“…The main purpose of grid verification is to reduce the discrete error as much as possible on the premise of saving computing resources. Therefore, the present grid verification mainly consists of two parts: 1) qualitatively analyze the influence of the total number of grids on the calculation results; 2) use the grid convergence index (GCI) to quantitatively evaluate the numerical precision of the target parameters ( Yi et al, 2022 ). A total of six meshes list in Table 2 are used to simulate the Denali filter case for grid verification.…”

“…Therefore, the structural optimization of IVCF is always a matter of concern. Recently, computational fluid dynamics (CFD) has become a useful and effective tool to study the effect of the filter structure on hemodynamic characteristics while both in vivo test and in vitro experiment have considerable difficulties of patient volunteers, setup incapability and high cost ( Wang et al, 2019 ; Shar et al, 2020 ; Uchiyama et al, 2021 ; Yi et al, 2022 ).…”

Machine Learning for Aiding Blood Flow Velocity Estimation Based on Angiography

“…According to the statistical data from the World Health Organization, cardiovascular associated diseases have become the topmost cause of death [ 1 , 2 ], and it has been identified that hemodynamic factors play a significant role in the development and progression of such diseases [ 3 , 4 , 5 , 6 ]. For example, the development of atherosclerosis is based on the observation that vascular inflammation and plaques are distributed near side branches or arterials stenosis, where blood flow is non-uniform, and at the lesser curvature of bends where the blood flow rate is relatively low [ 7 , 8 ].…”