scholarly journals Statistical wall shear stress maps of ruptured and unruptured middle cerebral artery aneurysms

2011 ◽  
Vol 9 (69) ◽  
pp. 677-688 ◽  
Author(s):  
L. Goubergrits ◽  
J. Schaller ◽  
U. Kertzscher ◽  
N. van den Bruck ◽  
K. Poethkow ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Dimensional Space ◽  
Neck Region ◽  
Spherical Shape ◽  
Unruptured Aneurysms ◽  
Ruptured Aneurysms ◽  
Wall Shear

Haemodynamics and morphology play an important role in the genesis, growth and rupture of cerebral aneurysms. The goal of this study was to generate and analyse statistical wall shear stress (WSS) distributions and shapes in middle cerebral artery (MCA) saccular aneurysms. Unsteady flow was simulated in seven ruptured and 15 unruptured MCA aneurysms. In order to compare these results, all geometries must be brought in a uniform coordinate system. For this, aneurysms with corresponding WSS data were transformed into a uniform spherical shape; then, all geometries were uniformly aligned in three-dimensional space. Subsequently, we compared statistical WSS maps and surfaces of ruptured and unruptured aneurysms. No significant ( p > 0.05) differences exist between ruptured and unruptured aneurysms regarding radius and mean WSS. In unruptured aneurysms, statistical WSS map relates regions with high (greater than 3 Pa) WSS to the neck region. In ruptured aneurysms, additional areas with high WSS contiguous to regions of low (less than 1 Pa) WSS are found in the dome region. In ruptured aneurysms, we found significantly lower WSS. The averaged aneurysm surface of unruptured aneurysms is round shaped, whereas the averaged surface of ruptured cases is multi-lobular. Our results confirm the hypothesis of low WSS and irregular shape as the essential rupture risk parameters.

scholarly journals Wall shear stress gradient is independently associated with middle cerebral artery aneurysm development: a case-control CFD patient-specific study based on 77 patients

BMC Neurology ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Mikołaj Zimny ◽  
Edyta Kawlewska ◽  
Anna Hebda ◽  
Wojciech Wolański ◽  
Piotr Ładziński ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Case Control ◽  
Independent Effect ◽  
Patient Specific ◽  
Aneurysm Formation ◽  
Wall Shear ◽  
Mca Aneurysm

Abstract Background Previously published computational fluid dynamics (CFD) studies regarding intracranial aneurysm (IA) formation present conflicting results. Our study analysed the involvement of the combination of high wall shear stress (WSS) and a positive WSS gradient (WSSG) in IA formation. Methods We designed a case-control study with a selection of 38 patients with an unruptured middle cerebral artery (MCA) aneurysm and 39 non-aneurysmal controls to determine the involvement of WSS, oscillatory shear index (OSI), the WSSG and its absolute value (absWSSG) in aneurysm formation based on patient-specific CFD simulations using velocity profiles obtained from transcranial colour-coded sonography. Results Among the analysed parameters, only the WSSG had significantly higher values compared to the controls (11.05 vs − 14.76 [Pa/mm], P = 0.020). The WSS, absWSSG and OSI values were not significantly different between the analysed groups. Logistic regression analysis identified WSS and WSSG as significant co-predictors for MCA aneurysm formation, but only the WSSG turned out to be a significant independent prognosticator (OR: 1.009; 95% CI: 1.001–1.017; P = 0.025). Significantly more patients (23/38) in the case group had haemodynamic regions of high WSS combined with a positive WSSG near the bifurcation apex, while in the control group, high WSS was usually accompanied by a negative WSSG (14/39). From the analysis of the ROC curve for WSSG, the area under the curve (AUC) was 0.654, with the optimal cut-off value −0.37 Pa/mm. The largest AUC was recognised for combined WSS and WSSG (AUC = 0.671). Our data confirmed that aneurysms tend to form near the bifurcation apices in regions of high WSS values accompanied by positive WSSG. Conclusions The development of IAs is determined by an independent effect of haemodynamic factors. High WSS impacts MCA aneurysm formation, while a positive WSSG mainly promotes this process.

scholarly journals Low Wall Shear Stress Is Independently Associated With the Rupture Status of Middle Cerebral Artery Aneurysms

Stroke ◽  
2013 ◽  
Vol 44 (2) ◽  
pp. 519-521 ◽  
Author(s):  
Yoichi Miura ◽  
Fujimaro Ishida ◽  
Yasuyuki Umeda ◽  
Hiroshi Tanemura ◽  
Hidenori Suzuki ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Wall Shear ◽  
Middle Cerebral Artery Aneurysms

scholarly journals Impact of blood rheology on wall shear stress in a model of the middle cerebral artery

2013 ◽  
Vol 3 (2) ◽  
pp. 20120094 ◽  
Author(s):  
Miguel O. Bernabeu ◽  
Rupert W. Nash ◽  
Derek Groen ◽  
Hywel B. Carver ◽  
James Hetherington ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Decomposition Analysis ◽  
Blood Rheology ◽  
Vascular Pathology ◽  
Newtonian Model ◽  
Wall Shear ◽  
The Impact

Perturbations to the homeostatic distribution of mechanical forces exerted by blood on the endothelial layer have been correlated with vascular pathologies, including intracranial aneurysms and atherosclerosis. Recent computational work suggests that, in order to correctly characterize such forces, the shear-thinning properties of blood must be taken into account. To the best of our knowledge, these findings have never been compared against experimentally observed pathological thresholds. In this work, we apply the three-band diagram (TBD) analysis due to Gizzi et al. (Gizzi et al. 2011 Three-band decomposition analysis of wall shear stress in pulsatile flows. Phys. Rev. E 83 , 031902. ( doi:10.1103/PhysRevE.83.031902 )) to assess the impact of the choice of blood rheology model on a computational model of the right middle cerebral artery. Our results show that, in the model under study, the differences between the wall shear stress predicted by a Newtonian model and the well-known Carreau–Yasuda generalized Newtonian model are only significant if the vascular pathology under study is associated with a pathological threshold in the range 0.94–1.56 Pa, where the results of the TBD analysis of the rheology models considered differs. Otherwise, we observe no significant differences.

STUDY ON THE RELATIONSHIP BETWEEN WALL SHEAR STRESS AND ASPECT RATIO OF CEREBRAL ANEURYSMS WITH DIFFERENT PRESSURE DIFFERENCES USING CFD SIMULATIONS

2018 ◽  
Vol 18 (05) ◽  
pp. 1850055
Author(s):  
ALFREDO ARANDA ◽  
ALVARO VALENCIA
Keyword(s):  
Shear Stress ◽  
Aspect Ratio ◽  
Wall Shear Stress ◽  
Cerebral Aneurysms ◽  
Cfd Simulations ◽  
Unruptured Aneurysms ◽  
Ruptured Aneurysms ◽  
Sphericity Index ◽  
Wall Shear ◽  
The Relationship

CFD simulations were performed for 60 human cerebral aneurysms (30 previously ruptured and 30 previously unruptured) to study the behavior of the time-averaged wall shear stress (TAWSS) with respect to the aspect ratio (AR), implementing a set of low, normal, and high-pressure differences between the inlet and the outlets of each artery. It is well known that there exists a direct relationship between TAWSS and the rupture. In this investigation, we presented an important result because the condition of the pressure among the branches and the AR may be measured in any patient, then a slope may be associated, and finally a TAWSS may be estimated. We found that when the pressure difference increased, the absolute slopes between TAWSS and AR increased as well. Also, the magnitude of the slope in the previously unruptured aneurysms was 4.7 times the slope in the previously ruptured aneurysms. On the other hand, TAWSS was higher in the previously unruptured aneurysm than previously ruptured aneurysms due to the unruptured aneurysms that have a smaller surface area. Furthermore, we analyzed the relationship between TAWSS and other geometric parameters of the aneurysm, such as bottleneck and non-sphericity index; however, no correlation was found for either cases.

Effect of elasticity on wall shear stress inside cerebral aneurysm at anterior cerebral artery

2016 ◽  
Vol 24 (3) ◽  
pp. 349-357 ◽  
Author(s):  
Lijian Xu ◽  
Michiko Sugawara ◽  
Gaku Tanaka ◽  
Makoto Ohta ◽  
Hao Liu ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Cerebral Aneurysm ◽  
Cerebral Artery ◽  
Anterior Cerebral Artery ◽  
Wall Shear

scholarly journals Numerical Simulation of Dispersed Particle-Blood Flow in the Stenosed Coronary Arteries

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Mongkol Kaewbumrung ◽  
Somsak Orankitjaroen ◽  
Pichit Boonkrong ◽  
Buraskorn Nuntadilok ◽  
Benchawan Wiwatanapataphee
Keyword(s):  
Numerical Simulation ◽  
Blood Flow ◽  
Shear Stress ◽  
Coronary Artery ◽  
Pressure Drop ◽  
Wall Shear Stress ◽  
Stokes Equations ◽  
Spherical Shape ◽  
Shear Stresses ◽  
Wall Shear

A mathematical model of dispersed bioparticle-blood flow through the stenosed coronary artery under the pulsatile boundary conditions is proposed. Blood is assumed to be an incompressible non-Newtonian fluid and its flow is considered as turbulence described by the Reynolds-averaged Navier-Stokes equations. Bioparticles are assumed to be spherical shape with the same density as blood, and their translation and rotational motions are governed by Newtonian equations. Impact of particle movement on the blood velocity, the pressure distribution, and the wall shear stress distribution in three different severity degrees of stenosis including 25%, 50%, and 75% are investigated through the numerical simulation using ANSYS 18.2. Increasing degree of stenosis severity results in higher values of the pressure drop and wall shear stresses. The higher level of bioparticle motion directly varies with the pressure drop and wall shear stress. The area of coronary artery with higher density of bioparticles also presents the higher wall shear stress.

G0200101 Evaluation of Wall Shear Stress on Cerebral Artery Using CFD

2015 ◽  
Vol 2015 (0) ◽  
pp. _G0200101--_G0200101-
Author(s):  
Ayumi MITOH ◽  
Eitarou KOYABU ◽  
Eiji SOBU ◽  
Tadashi KASHIMA ◽  
Sinichi IKEDA ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Cerebral Artery ◽  
Wall Shear

Wall Shear Stress and Gradient at Anterior Communicating Artery in Pulsating Flow

2000 ◽  
Author(s):  
Ryuhei Yamaguchi ◽  
Susumu Kudo ◽  
Hiroyuki Yamanobe ◽  
Mikio Nakajima ◽  
Hiroshi Ujiie
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Cerebral Artery ◽  
Major Part ◽  
Cerebral Arteries ◽  
Circle Of Willis ◽  
Pulsating Flow ◽  
Anterior Communicating Artery ◽  
Wall Shear

Abstract The aneurysm in the cerebral artery is apt to initiate around the “Circle of Willis”. The anterior communicating artery (ACoA), which composes one of major part of the circle of Willis, is the most predilection artery of the aneurysm. This artery is characterized by a singular geometry. At this artery, two proximal anterior cerebral arteries (A1, confluence) join facing each other. Just at this artery, the flow bifurcates two distal anterior cerebral arteries (A2, bifurcation). Namely, this artery has a function as a bypass channel. Therefore, the flow around the anterior communicating artery would be very unstable. The aneurysm arises around the apex of this artery where the confluent flow collides.

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