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Long-term exposure to risk factors will lead to coronary atherosclerosis, which will lead to the formation and progression of coronary plaque. Early identification of high-risk plaque characteristics will help prevent plaque rupture or erosion, thus avoiding the occurrence of acute cardiovascular events. Biomechanical stress plays an important role in progression and rupture of atherosclerotic plaques. In recent years, non-invasive coronary computed tomography angiography (CCTA) computational fluid dynamics (CFD) modeling has made it possible to acquire the corresponding biomechanical stress parameters. These coronary biomechanical stress parameters, especially wall shear stress (WSS), will aid in the development of a more accurate clinical model for predicting plaque progression and major adverse cardiovascular events ( MACE ). In this review, the biomechanical stress and the role of WSS from CCTA in atherosclerosis were introduced, and the researches on the relationship between biomechanical stress from CCTA and coronary artery diseases were discussed.
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Objective To propose a two-way fluid-structure interaction (FSI) method based on real patients with carotid artery stenosis, and analyze the hemodynamic parameters of carotid plaques with different types at the lesion as well as deformation and stress changes of the plaque itself. Methods Three-dimensional ( 3D) modeling was performed based on computed tomography angiography ( CTA) data of patients with moderate carotid artery stenosis. The carotid artery wall model and plaque model were separated, and transient fluid structure coupling calculation was performed. The situation from early stage of carotid atherosclerosis to formation of the plaque was simulated. The plaque types were divided into thickened plaques, lipid plaques, mixed plaques and calcified plaques, among which thickened plaques were regarded as non-plaque conditions for representing the thickening of vascular intima-media. The stenotic carotid arteries with different plaque types were compared and analyzed. Results The plaques with different types had little effect on the overall blood flow, but the wall shear stress of lipid plaques at the lesion was lower than that of other plaques. With thickened plaques as a control, concurrence of the plaque would inhibit artery expansion, and lipid plaques were the most obvious. Calcified plaques had the highest average plaque structure stress, while lipid plaques had the lowest average plaque structure stress. Conclusions The method proposed in this study can analyze fluid area and solid area at the same time. The results can contribute to better understanding the influence of different plaque types on carotid artery diseases.
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@#This study aimed to investigate the irrigation dynamics of the positive pressure side-vented (SV) needle, EndoVac (micropores) needle and modified apical negative pressure (mANP) open-ended needle using computational fluid dynamics (CFD). A simulation of a prepared root canal (conical frustum) of 15 mm length with an apical diameter of 0.40 mm following Protaper F4 apical preparation was created using three-dimensional (3D) CAD software. The 3D simulated needle of SV 30G needle, EndoVac with micropores needle and mANP, 30G flat open-ended needle were also created. The irrigation dynamics were evaluated through transient CFD simulations. In addition, the irrigation dynamics of mANP at 0.2 mm, 0.5 mm, and 1.0 mm short from the working length were also assessed. The EndoVac and mANP showed negative apical static pressure and streamline patterns able to reach the apical region, thus indicating negligible extrusion. Meanwhile, SV showed positive apical static pressure and almost nonexistent streamlines beyond the needle tip. The SV showed the highest wall shear stress (WSS) magnitude of 1030Pa whereas Endovac (161 Pa) and mANP1 (258 Pa). However, SV revealed lower average WSS (10 Pa) compared to mANP1 (13 Pa) and mANP2 (11 Pa). This is due to SV developed a localised maximum WSS opposite the open vent area only therefore, uneven distribution of WSS. The EndoVac system developed a localised maximum WSS in the pair of micropores furthest away from the apical. CFD analysis of the EndoVac, mANP and SV showed different technique approach, needle design and needle depths insertion affect the irrigation dynamics pattern and magnitude.
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@#Objective To discuss the feasibility of establishment of animal model of "functional" bicuspid aortic valve with swine and observe its effect on the wall shear stress inside the aorta. Methods Four common Shanghai White Swine with body weight between 50 kg to 55 kg were selected. Under general anesthesia and cardiopulmonary bypass, the aortic transverse incision approach was used, continuous suture with 6-0 polypropylene to align the left and right coronary valve leaflets to create a bicuspid valve morphology. After the operation, echocardiography was used to observe the aortic valve morphology and the hemodynamic changes of the aortic valve orifice. The effect on the wall shear stress inside the aorta was studied with 4D-Flow magnetic resonance imaging (MRI). Results A total of 4 swine "functional" bicuspid aortic valve models were established, with a success rate of 100.0%. Echocardiography showed that the blood flow velocity of the aortic valve orifice was faster than that before the operation (0.96 m/s vs. 1.80 m/s). 4D-Flow MRI showed abnormally increased wall shear stress and blood flow velocity in the aorta of the animal models. After the surgery, in model animals, the maximal wall shear stress inside the ascending aorta was greater than 1.36 Pa, and the maximum blood flow velocity was greater than 1.4 m/s. Conclusion Establishment of the animal model of "functional" bicuspid aortic valve in swine is feasible, scientific and reliable. It can be used in researches on evaluating the pathophysiological changes.
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Objective:To investigate the relationship between wall shear stress (WSS) and the degree of lumen stenosis and plaque characteristics in patients with atherosclerotic stenosis in the middle brain.Methods:Thirty-four patients with moderate to severe unilateral middle cerebral artery stenosis in Nanjing First Hospital from June 2020 to June 2021 were analyzed retrospectively. All patients underwent routine magnetic resonance imaging and vascular wall imaging to obtain plaque parameters such as plaque area, remodeling mode and remodeling index. Based on magnetic resonance angiography, a computational fluid dynamics model was established to simulate the local hemodynamics near the lesion and quantify WSS. The patients were divided into high WSS group and low WSS group according to the median WSS. The differences of clinical baseline data, degree of lumen stenosis and plaque characteristics between the two groups were compared. Pearson correlation analysis was used to calculate the correlation between WSS and lumen stenosis and plaque characteristics.Results:A total of 34 patients were included in this study, 17 in the high WSS group and 17 in the low WSS group. Compared with the low WSS group, the plasma homocysteine level in the high WSS group was lower [(11.10±4.96) μmol/L vs (16.97±6.98) μmol/L, t=-2.83, P=0.010], the degree of stenosis was lower (0.56±0.05 vs 0.66±0.08, t=-4.54, P<0.001), and the proportion of positive lumen remodeling was higher (12/17 vs 4/17, P=0.015). Pearson correlation analysis showed that the degree of lumen stenosis was negatively correlated with WSS ( r=-0.44, P=0.011), and the plaque area was not correlated with WSS. Conclusions:WSS in middle cerebral artery stenosis is related to the degree of lumen stenosis and the mode of vascular remodeling. Higher WSS has poor stability, but lower WSS is more likely to cause lumen stenosis.
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To explore the influence of bionic texture coronary stents on hemodynamics, a type of bioabsorbable polylactic acid coronary stents was designed, for which a finite element analysis method was used to carry out simulation analysis on blood flow field after the implantation of bionic texture stents with three different shapes (rectangle, triangle and trapezoid), thus revealing the influence of groove shape and size on hemodynamics, and identifying the optimal solution of bionic texture groove. The results showed that the influence of bionic texture grooves of different shapes and sizes on the lower wall shear stress region had a certain regularity. Specifically, the improvement effect of grooves above 0.06 mm on blood flow characteristics was poor, and the effect of grooves below 0.06 mm was good. Furthermore, the smaller the size is, the better the improvement effect is, and the 0.02 mm triangular groove had the best improvement effect. Based on the results of this study, it is expected that bionic texture stents have provided a new method for reducing in-stent restenosis.
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Bionics , Computer Simulation , Coronary Vessels , Hemodynamics/physiology , Models, Cardiovascular , Stents , Stress, MechanicalABSTRACT
Objective:To observe the effect of modified Tongqiao Huoxuetang on circulating blood flow and wall shear stress of vertebrobasilar dolichoectasia (VBD) due to blood stasis and channel blockage. Method:A total of 97 patients admitted in our department from October 2017 to August 2019 were collected. The traditional Chinese medicine (TCM) syndromes were consistent with blood stasis and channel blockage, and diagnosed as VBD by magnetic resonance angiography (MRA). The patients were divided into experimental group (48 cases) and control group (49 cases). Control group was given basic therapy and placebo of TCM, while treatment group was given basic therapy and modified Tongqiao Huoxuetang for 30 days. The degree of relief of vertigo symptoms, vertigo symptom scale (VSS), activity balance confidence (ABC), transcranial doppler (TCD) bilateral vertebral artery and basilar artery blood flow velocity [systolic blood flow velocity (Vs), mean blood flow velocity (Vm), diastolic blood flow velocity (Vd)], mean blood flow differences between (MFV), pulsatility index, resistance index (RI), and wall shear force (WSS) were observed before and after treatment. Result:Compared with control group before treatment, the score of ABC scale in control group after treatment was markedly higher, while the score of VSS was significantly lower (P<0.05). However, there was no statistical significance in the score of vertigo symptom. Compared with treatment group before treatment, the symptom grade of vertigo degree and the score of VSS in treatment group after treatment were substantially lower, while the score of ABC scale was significantly higher (P<0.05). Compared with control group, the score of vertigo degree symptoms and VSS in treatment group were markedly lower, while the score of ABC scale was significantly higher (P<0.05). Compared with control group before treatment, Vm, MFV and WSS of bilateral vertebral artery in control group after treatment were substantially higher, while RI was significantly lower (P<0.05). However, there were no statistical significances in Vs, Vd and PI in control group before and after treatment. Compared with treatment group, Vs, Vd, Vm, MFV and WSS of bilateral vertebral artery in treatment group after treatment were markedly higher, while RI was significantly lower (P<0.05). However, there was no statistical significance in PI of experimental group before and after treatment. Compared with control group after treatment, Vs, Vd, Vm, MFV and WSS of bilateral vertebral artery in treatment group after treatment were substantially higher, while there was no statistical significance in PI and RI. Before and after treatment, there were similar changes in blood flow parameters of the basilar artery and bilateral vertebral artery. Conclusion:Modified Tongqiao Huoxuetang could improve the clinical symptoms of dizziness or vertigo in patients of VBD due to blood stasis and channel blockage, and the mechanism might be related to the improvement of post-circulation hemodynamics by Tongqiao Huoxuetang.
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BACKGROUND: Sand therapy has been shown to exhibit a positive effect on reducing femoral atherosclerosis and inhibiting thrombosis. OBJECTIVE: To investigate the effects of sand therapy on hemodynamic parameters of different stenosis models of femoral bifurcation through comparing the hemodynamic parameters and wall shear stress in four stenosis models before and after sand therapy. METHODS: The study protocol was performed in strict accordance with the relevant ethical requirements of School of Mechanical Engineering of Xinjiang University. Each participant provided written informed consent. Medical software Mimics10.01, reverse engineering software Geomagic Studio 2012 and three-dimensional CAD software UG8.5 were used to separate and optimize the CT data of a subject’s lower extremities and the geometric model of the femoral artery bifurcation was obtained. According to the classification criteria of vascular stenosis caused by femoral atherosclerotic plaque in the lower extremity, the degree of plaque stenosis on the side wall of the femoral bifurcation tube was set as 0% (normal), 15% (normal), 30% (mild) and 50% (moderate). Computational fluid dynamics method was used for numerical simulation. The Laminar flow model was selected for blood flow before sand therapy, and the standard turbulence model κ-ε was selected for blood flow after sand therapy. Blood flow velocity and wall shear stress were analyzed before and after sand therapy. RESULTS AND CONCLUSION: The maximum blood flow velocity after sand therapy was 0.35-0.45 m/s higher than that before sand therapy. After sand therapy, the wall shear stress at the stenosis was increased by 5-11 Pa compared with that before sand therapy, and the wall shear stress at 50% vascular stenosis rate model reached 41 Pa. These results suggest that the trend of atherosclerotic plaque enlargement is decreased after sand therapy, but patients with 50% (moderate) vascular stenosis have the risk of plaque rupture.
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Objective To analyze the hemodynamic parameters of anomalous origin of the right coronary artery from the left coronary artery sinus (AORL) based on computational fluid dynamics (CFD), so as to make an evaluation of the disease. Methods A normal right coronary artery (RCA) case and an AORL case were selected. Two models were reconstructed in Mimics software and imported into ANSYS CFX software for hemodynamics simulation. The hemodynamics of normal RCA model and AORL model were compared. Results AORL model had a smaller volume flow (9.35 cm3/s), which might lead to insufficient blood supply downstream of the RCA; the pressure at the acute corner of AORL model (13.78 kPa) was lower than normal RCA model (14.9 kPa); the wall shear stress (WSS) of AORL model (12.83 Pa) was larger than that of normal RCA model (9.74 Pa); the total deformation of AORL model was relatively large. Conclusions The entrance velocity and pressure of AORL were lower than those of normal RCA, which might lead to ischemic symptoms. The research findings are of theoretical significance for the effective evaluation of ischemia and other diseases in clinic.
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Objective Hemodynamic disorder of the pulmonary artery (PA) is the main cause of pulmonary arterial hypertension related to congenital heart disease (PAH-CHD). To study the hemodynamic characteristics of PA, so as to understand biomechanical factors in the occurrence and development of PAH-CHD. Methods Clinical and imaging data were collected in five PAH-CHD patients and five matched controls (Non-PAH) to reconstruct subject-specific three-dimensional (3D) PA models. Computational fluid dynamics (CFD) was performed to compare the hemodynamic difference of flow patterns, wall shear stress (WSS) and normalized energy loss (E·) in the two groups. Results Hemodynamics-related parameters showed that the velocity and WSS were higher in the left and right PA branches of PAH-CHD patients, with significantly lower WSS in the main PA. The E· significantly increased in PAH-CHD patients and positively correlated with normalized PA diameter and inflow. Conclusions Compared with Non-PAH subjects, PAH-CHD patients have obviously higher velocity and WSS in PA branches, lower WSS in main PA and greater E·, indicating these hemodynamic parameters are related with the PAH-CHD, which can be used as potential biomechanical factors for the clinical evaluation of PAH-CHD.
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Objective To investigate the effects of fluid shear stress on rolling adhesion of neutrophils on immobilized platelets under flows. Methods Experiments were performed at the parallel plate flow chamber. Platelets were adhered to the functionalized flow chamber bottom which were coated with vWF-A1 first, and then washed with PBS under wall shear stress (WSS) of 1 Pa for different time (0 min, 2.5 min, 7.5 min). A high-speed camera was used to observe and record the rolling adhesion events of neutrophils on immobilized platelets under 50 mPa WSS, and the adhesion parameters such as the number of adhesion events, the tether lifetime of cells and rolling velocity. Results Neutrophils could specifically bind to the immobilized platelets on vWF-A1-coated bottom of the flow chamber. Mechanical stimulation on immobilized platelets had no effects on the tether lifetime of neutrophils on the platelets, but up-regulated the adhesive ratio of neutrophils on the platelets and slowed down the rolling of neutrophils on the platelets. Conclusions Mechanical stimulation on the immobilized platelets will significantly make the circulating neutrophils to be captured easily and promote the rolling adhesion of neutrophils on platelets.
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ABSTRACT: Bicuspid aortic valve (BAV) disease is generally associated with thoracic aortic dilatation (TAD). Related factors include; genetical, morphological (valvular phenotype) and most recently, hemodynamic profiles associated with flow pattern and wall shear stress. Cardiac magnetic resonance 4D Flow (4DF) can give an integral evaluation of these later flow variables. Remarkable, different spectrums of flow and vortex direction exist in BAV that are related to the site of TAD (proximal or distal). Therefore, we present a 57 years old patient with BAV (Sievers 0) with anteroposterior leaflets distribution in which 4DF depicted an anteriorly and righthand oriented jet that correlated with the zone of grater AD; also, vortex rotation was counterclockwise, corresponding to the most frequent vortex type in BAV. In conclusion, 4DF is a powerful and ground-breaking tool that enhances our knowledge of BAV related aortopathy.
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Magnetic Resonance Imaging, Cine/methods , Bicuspid Aortic Valve Disease , Aortic Aneurysm , Aortic Diseases/physiopathology , Image Interpretation, Computer-Assisted , Cardiovascular Diseases/diagnostic imaging , Imaging, Three-Dimensional , Cardiac-Gated Imaging Techniques/methodsABSTRACT
Objectives To evaluate the parameter changes of posterior circulation blood flow and wall shear stress in patients with vertebral artery hypoplasia (VAH) and to understand the possible mechanisms of VAH-induced posterior circulation infarction (PCI). Methods A total of 261 consecutive patients with suspected vascular vertigo admitted to the Department of Neurology, People's Hospital of Zhengzhou from October 2014 to January 2016 were enrolled. The vertigo symptom scale (VSS) was used to evaluate the severity of vertigo. All patients completed TCD and high field strength MR examination within 3 d of admission (Tl ,T2 weighted imaging,fluid attenuation inversion recovery [FLAIR] ,diffusion-weighted imaging [DWI],MR angiography [MRA], contrast-enhanced MRA [CEMRA]),and according to the diameter of the vertebral artery combined with the diagnostic criteria of VAH, they were divided into VAH group and non-VAH group, Posterior circulation blood flow velocity (systolic velocity [V,], diastolic velocity [Vd] , mean velocity [V]) , pulsatility index (PI) , resistance index (RI) , mean flow velocity (MFV) ,and wall shear stress (WSS) between the two group were analyzed. The paired or independent sample t test, Mann-Whitney U test and the 2 test were conducted with SPSS19.0 for intra-group or inter-group comparisons. Results Of 261 patients,78 (29.9%) had VAH,26 were complicated with basilar artery hypoplasia,37 were complicated with fetal type posterior circle of Willis,and posterior circulation infarction occurred in 48 (18. 4%). Compared with the non-VAH group, the degree of vertigo of patients was more severe in the VAH group(3[2,4] vs. 3[1,3] ,Z = 2. 29) ,and the incidence of posterior circulation infarction was significantly increased (25. 6% [20/78] vs. 13. 5% (28/183) ,x =5- 34)- The differences were statistically significant (all P 0. 05). Conclusions The incidence of VAH was higher in patients with vertigo and vascular risk factors. VAH affected the posterior circulation hemodynamics, which might be associated with the occurrence of PCI.
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Objective To study the effects of abnormal blood flow on the secretion of ET-1/NO and the expression of the mRNA and the protein of ET-1, eNOS, VCAM-1, ICAM-1 and MCP-1 in human umbilical vein endothelial cells (HUVECs), so as to explore the mechanism of atherosclerosis （AS） caused by abnormal hemodynamics. MethodsThe HUVECs were divided into stress group, wall pressure group and normal group according to the different stress. The HUVECs were cultured under the corresponding stress for 24 hours and then collected. The secretion levels of NO and ET-1 were detected by enzyme method and radioimmunoassay method. The mRNA expression levels of eNOS and ET-1 were detected by qPCR. The expression levels of the mRNA and the protein of VCAM-1, ICAM-1, MCP-1 were detected by qPCR and Western blot. Results Compared with normal group, the secretion level and the mRNA expression level of ET-1 in wall pressure group increased significantly (P＜0.01), and the secretion level of NO and the mRNA expression level of eNOS in stress group also increased significantly (P＜0.01), The expressions level of the mRNA and the protein of VCAM-1, ICAM-1 and MCP-1 obviously increased in stress group and wall pressure group (P＜0.01). Conclusions Stress or wall pressure acting on HUVECs alone could lead to its dysfunction of the secretion and the expression of gene and protein. The mechanism of AS caused by abnormal blood flow was related to these dysfunction of HUVEC.
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Objective To study the effect of sand therapy on the hemodynamics of flexural femoral artery, and further reveal the therapeutic mechanism of sand therapy from the perspective of hemodynamics. Methods The three-dimensional finite element model of the curved femoral artery was established based on CT images of human aorta, and the data of heart rate, peak blood flow velocity and inner diameter of femoral artery measured by the experiment were used as initial conditions and boundary conditions to carry out finite element numerical simulation. The blood flow velocity, pressure and wall shear stress before and after sand therapy were analyzed and compared under fluid-solid coupling condition. Results Compared with treatment before sand therapy, the longitudinal velocity of the flexural segment of blood vessel increased significantly, with an increase of 22.76%. The secondary reflux velocity decreased significantly, with a relative decrease of 18.26%. The wall shear stress decreased by 2.01% after sand therapy. Conclusions Sand therapy had a significant effect on blood fluidity, by improving blood flow of femoral arteries, and preventing deposition of arterial platelets. The transverse flow phenomenon was obviously weakened after sand therapy, which could avoid the deposition of substances in blood and had a positive effect on the prevention of atherosclerosis, thrombosis and other vascular diseases.
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Objective To investigate the in vivo stress distribution of the atherosclerotic plaque at carotid bifurcation, so as to provide references for the mechanical mechanisms of plaque rupture at carotid bifurcation and the design for further medical treatment. Methods The three-dimensional geometric model of carotid bifurcation and plaque were established according to average geometric parameters of human carotid bifurcation. Residual stress of the carotid bifurcation and plague was reestablished with “thermal-structure” coupling method, and in vivo stresses of vessels with the plaque at carotid bifurcation under blood pressure and blood flow were calculated. Results Both the maximum principal stress and elastic shear stress concentrated on the shoulder of the plaque. Elastic shear stress increased with the increase of stenosis ratio and blood pressure. Wall shear stress in the upstream of the plaque was considerably higher than that of the downstream. The distribution of oscillatory shear index(OSI) was quite the opposite. The changing patterns of the elastic shear stress and flow shear stress were quite different with the change of stenosis ratios. Conclusions Tension grew gradually from the centrality to shoulder surface of the plaque. The centrality of the plaque might bear compression when the stenosis was very severe. The periodic variation of the structural stress might cause structural fatigue of the plaque, thus increasing the rupture risk. Distinction of the component and vulnerability of the plaque between upstream and downstream might be caused by differences in hemodynamic parameters of the plaque between upstream and downstream.
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Objective To reduce the thrombosis probability and hemolysis risk of the meglev left ventricular assist device (LVAD), so as to increase the efficiency of blood supply. Methods The influences of the pump outlet diameter, exit angle, fillet size between the outlet and the inner wall of the pump, as well as gap between the rotor and the shell on internal flow field of the pump were studied by using the computational fluid dynamics (CFD) method, so as to optimize the internal structure and improve the hydrodynamic performance of the pump. Results Compared with pump of the previous generation, the maximum wall shear stress (WSS) of the pump inner wall, the maximum WSS of the pump rotor, the area with WSS >200 Pa were reduced by 23.6%, 47.4%, 76.2%, respectively, while the outlet flow was increased by 14.4%. Conclusions For the meglev LVAD of the new generation, its internal blood flow tended to be smooth, and the hemodynamic performance of blood flow was improved comprehensively. The research findings provide references for optimization design of the meglev LVAD and related experimental researches in the future.
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Objective To study the effects of abnormal blood flow on the secretion of ET-1/NO and the expression of the mRNA and the protein of ET-1, eNOS, VCAM-1, ICAM-1 and MCP-1 in human umbilical vein endothelial cells (HUVECs), so as to explore the mechanism of atherosclerosis （AS） caused by abnormal hemodynamics. MethodsThe HUVECs were divided into stress group, wall pressure group and normal group according to the different stress. The HUVECs were cultured under the corresponding stress for 24 hours and then collected. The secretion levels of NO and ET-1 were detected by enzyme method and radioimmunoassay method. The mRNA expression levels of eNOS and ET-1 were detected by qPCR. The expression levels of the mRNA and the protein of VCAM-1, ICAM-1, MCP-1 were detected by qPCR and Western blot. Results Compared with normal group, the secretion level and the mRNA expression level of ET-1 in wall pressure group increased significantly (P＜0.01), and the secretion level of NO and the mRNA expression level of eNOS in stress group also increased significantly (P＜0.01), The expressions level of the mRNA and the protein of VCAM-1, ICAM-1 and MCP-1 obviously increased in stress group and wall pressure group (P＜0.01). Conclusions Stress or wall pressure acting on HUVECs alone could lead to its dysfunction of the secretion and the expression of gene and protein. The mechanism of AS caused by abnormal blood flow was related to these dysfunction of HUVEC.
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Objective To study the effect of sand therapy on the hemodynamics of flexural femoral artery, and further reveal the therapeutic mechanism of sand therapy from the perspective of hemodynamics. Methods The three-dimensional finite element model of the curved femoral artery was established based on CT images of human aorta, and the data of heart rate, peak blood flow velocity and inner diameter of femoral artery measured by the experiment were used as initial conditions and boundary conditions to carry out finite element numerical simulation. The blood flow velocity, pressure and wall shear stress before and after sand therapy were analyzed and compared under fluid-solid coupling condition. Results Compared with treatment before sand therapy, the longitudinal velocity of the flexural segment of blood vessel increased significantly, with an increase of 22.76%. The secondary reflux velocity decreased significantly, with a relative decrease of 18.26%. The wall shear stress decreased by 2.01% after sand therapy. Conclusions Sand therapy had a significant effect on blood fluidity, by improving blood flow of femoral arteries, and preventing deposition of arterial platelets. The transverse flow phenomenon was obviously weakened after sand therapy, which could avoid the deposition of substances in blood and had a positive effect on the prevention of atherosclerosis, thrombosis and other vascular diseases.
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OBJECTIVE: The objective of this study was to analyze patient-specific blood flow in ruptured aneurysms using obtained non-Newtonian viscosity and to observe associated hemodynamic features and morphological effects.METHODS: Five patients with acute subarachnoid hemorrhage caused by ruptured posterior communicating artery aneurysms were included in the study. Patients’ blood samples were measured immediately after enrollment. Computational fluid dynamics (CFD) was conducted to evaluate viscosity distributions and wall shear stress (WSS) distributions using a patient-specific geometric model and shear-thinning viscosity properties.RESULTS: Substantial viscosity change was found at the dome of the aneurysms studied when applying non-Newtonian blood viscosity measured at peak-systole and end-diastole. The maximal WSS of the non-Newtonian model on an aneurysm at peaksystole was approximately 16% lower compared to Newtonian fluid, and most of the hemodynamic features of Newtonian flow at the aneurysms were higher, except for minimal WSS value. However, the differences between the Newtonian and non-Newtonian flow were not statistically significant. Rupture point of an aneurysm showed low WSS regardless of Newtonian or non-Newtonian CFD analyses.CONCLUSION: By using measured non-Newtonian viscosity and geometry on patient-specific CFD analysis, morphologic differences in hemodynamic features, such as changes in whole blood viscosity and WSS, were observed. Therefore, measured non-Newtonian viscosity might be possibly useful to obtain patient-specific hemodynamic and morphologic result.