Influence of stent-induced vessel deformation on hemodynamic feature of bloodstream inside ICA aneurysms

Modeling and evaluation of biomechanics and hemodynamic based on patient-specific small intracranial aneurysm using fluid-structure interaction

BACKGROUND AND OBJECTIVE

Rupture of small intracranial aneurysm (IA) often leads to the development of highly fatal clinical syndromes such as subarachnoid hemorrhage. Due to the patient specificity of small IA, there are many difficulties in evaluating the rupture risk of small IA such as multiple influencing factors, high clinical experience requirements and poor reusability.

METHODS

In this study, clinical methods such as transcranial doppler (TCD) and magnetic resonance imaging (MRI) are used to obtain patient-specific parameters, and the fluid-structure interaction method (FSI) is used to model and evaluate the biomechanics and hemodynamics of patient-specific small IA.

RESULTS

The results show that a spiral vortex stably exists in the patient-specific small IA. Due to the small size of the patient-specific small IA, the blood flow velocity still maintains a high value with maximum reaching 3 m/s. The inertial impact of blood flow and vortex convection have certain influence on hemodynamic and biomechanics parameters. They cause three high value areas of WSSM on the patient-specific small IA with maximum of 180 Pa, 130 Pa and 110 Pa, respectively. They also cause two types of WSS concentration points, positive normal stress peak value areas and negative normal stress peak value areas to appear.

CONCLUSION

This paper found that the factors affecting hemodynamic parameters and biomechanical parameters are different. Unlike hemodynamic parameters, biomechanical parameters are also affected by blood pressure in addition to blood flow velocity. This study reveals the relationship between the flow field distribution and changes of patient-specific small IA, biomechanics and hemodynamics.

Usage of computational method for hemodynamic analysis of intracranial aneurysm rupture risk in different geometrical aspects

The importance of the parent vessel geometrical feature on the risk of cerebral aneurysm rupture is unavoidable. This study presents inclusive details on the hemodynamics of Internal carotid artery (ICA) aneurysms with different parent vessel mean diameters. Different aspects of blood hemodynamics are compared to find a reasonable connection between parent vessel mean diameter and significant hemodynamic factors of wall shear stress (WSS), oscillatory shear index (OSI), and pressure distribution. To access hemodynamic data, computational fluid dynamics is used to model the blood stream inside the cerebral aneurysms. A hemodynamic comparison of the selected cerebral aneurysm shows that the minimum WSS is reduced by about 71% as the parent vessel's mean diameter is increased from 3.18 to 4.48 mm.

Influence of parent vessel feature on the risk of internal carotid artery aneurysm rupture via computational method

In this study, the role of sac section area and parent vessel diameter on the hemodynamic feature of the blood flow in selected internal carotid artery (ICA) aneurysms is comprehensively investigated. The changes of wall shear stress, pressure, and oscillatory shear index (OSI) of blood stream on the vessel for various aneurysms with coiling treatment. To attain hemodynamic factors, computational technique is used for the modeling of non-Newtonian transient blood flow inside the three different ICA aneurysms. Three different saccular models with various Parent vessel mean Diameter is investigated in this study. The achieved outcomes show that increasing the diameter of the parent vessel directly decreases the OSI value on the sac surface. In addition, the mean wall shear stress decreases with the increase of the parent vessel diameter.

Computational and statistical analyses of blood hemodynamic inside cerebral aneurysms for treatment evaluation of endovascular coiling

Diagnosis of aneurysm and possibility of aneurysm rupture are crucial for avoiding brain hemorrhage. In this work, blood stream inside internal carotid arteries (ICAs) are simulated in diverse working conditions to disclose the importance of hemodynamic factors on the rupture of aneurysm. The main attention of this study is to investigate the role of hemodynamic on the aneurysm rupture. Statistical and computational methods are applied to investigate coiling porosity and blood hematocrit in 9 specific real ICA geometries. Response surface model (RSM) develops 25 runs to investigate all features of selected geometrical parameters and treatment factors. Computational fluid dynamic is used for the simulation of the blood stream in the selected aneurysms. The effects of sac section area and mean radius of parent vessel on blood hemodynamics are fully investigated. Hemodynamic factors are examined and compared at the peak systolic time instant, including pressure distributions, and velocity. Achieved results indicate that the increasing sac section area (from 36.6 to 75.4 mm2) results in 20% pressure reduction on the sac wall.

Impacts of morphology parameters on the risk of rupture in intracranial aneurysms: statistical and computational analyses

The hemodynamic analysis of the blood stream inside the cerebral aneurysms reveals the risk of the aneurysm rupture. In addition, the high risk region prone to rupture would be determined by the hemodynamic analysis of the blood. In present article, computational fluid dynamic is used for the investigation of the hemodynamic effects on the aneurysm wall and risk of rupture. This study tries to find the connection between the risk of rupture with three geometrical features of aneurysm i.e., Ellipsoid Max semi-axis, Size ratio and Tortuosity. Statistical analysis is done over 30 different ruptured /unruptured ICA aneurysms to find meaningful relation between selected geometrical factors and rupture risk. The hemodynamic analysis is done over four distinct aneurysm models to attain more details on effects of chosen geometrical factors. The results of simulations indicate that the Ellipsoid Max semi-axis have meaningful impacts on the risk of rupture.

The influence of sac centreline on saccular aneurysm rupture: computational study

The geometric characteristics of a saccular aneurysm play a crucial role in its rupturing. This article thoroughly investigates the impact of the sac centerline on aneurysm rupture, with a focus on identifying significant factors related to rupture at different time intervals. The study employs comprehensive computational simulations of six models of the ICA with varying coiling porosities and blood HCTs, using CFD analysis to examine WSS, OSI, pressure, and velocity within the saccular aneurysm for different sac centerlines. The results indicate that higher blood HCT levels lead to increased WSS and pressure values on the aneurysm wall, while OSI and mean velocity decrease. The study also reveals that coiling techniques can significantly reduce the risk of rupture, as decreasing coil porosity (increasing coil permeability) increases OSI and pressure while decreasing WSS and blood velocity within the aneurysm sac.

Computational fluid dynamics simulation of two-phase flow patterns in a serpentine microfluidic device

In the current research work, the flow behavior of a liquid-liquid extraction (LLE) process in a serpentine microchannel was analyzed. The simulation was performed using a 3D model and the results were found to be consistent with experimental data. The impact of the flow of chloroform and water on the flow model was also examined. The data indicate that once the aqua and organic phases flow rates are low and similar, a slug flow pattern is observed. However, as the overall flow rate raises, the slug flow transforms into parallel plug flow or droplet flow. An increment in the aqua flows while maintaining a constant organic phase flow rate results in a transition from slug flow to either droplet flow or plug flow. Finally, the patterns of flow rate in the serpentine micro-channel were characterized and depicted. The results of this study will provide valuable insights into the behavior of two-phase flow patterns in serpentine microfluidic devices. This information can be used to optimize the design of microfluidic devices for various applications. Furthermore, the study will demonstrate the applicability of CFD simulation in investigating the behavior of fluids in microfluidic devices, which can be a cost-effective and efficient alternative to experimental studies.

Reduction of rupture risk in ICA aneurysms by endovascular techniques of coiling and stent: numerical study

The initiation, growth, and rupture of cerebral aneurysms are directly associated with Hemodynamic factors. This report tries to disclose effects of endovascular technique (coiling and stenting) on the quantitative intra-aneurysmal hemodynamic and the rupture of cerebral aneurysms. In this paper, Computational Fluid Dynamic are done to investigate and compare blood hemodynamic inside aneurysm under effects of deformation (due to stent) and coiling of aneurysm. The blood stream inside the sac of aneurysm as well as pressure and OSI distribution on the aneurysm wall are compared in nine cases and results of two distinctive cases are compared and reported. Obtained results specifies that the mean WSS is reduced up to 20% via coiling of the aneurysm while the deformation of the aneurysm (applying stent) could reduce the mean WSS up to 71%. In addition, comparison of the blood hemodynamic shows that the blood bifurcation occurs in the dome of aneurysm when endovascular technique for the treatment is not applied. It is found that the bifurcation occurs at ostium section when ICA aneurysm is deformed by the application of stent. The impacts of coiling are mainly limited since the blood flow entrance is not limited in this technique and WSS is not reduced substantial. However, usage of stent deforms the aneurysm angle with the orientation of parent vessel and this reduces blood velocity at entrance of the ostium and consequently, WSS is decreased when deformation of the aneurysm fully occurs. These qualitative procedures provide a preliminary idea for more profound quantitative examination intended for assigning aneurysm risk of upcoming rupture.

Computational study of blood flow inside MCA aneurysm with/without endovascular coiling

The simulation of blood hemodynamics inside the MCA aneurysm is done to investigate the potential region for rupture and hemorrhage. The main focus of this work is to disclose the impacts of endovascular coiling on blood hemodynamics and the risk of aneurysm rupture. Navier-stokes equations are solved for the computational study of blood flow while it is assumed that flow remains laminar, unsteady, and non-Newtonian. Influences of blood hematocrits and coiling porosity are also examined in this work. Obtained results show that impacts of blood hematocrit on the maximum OSI are limited in the MCA case.