Blood Flow Characteristics In Arteries Research Articles

Advancing Blood Flow in Stenotic Arteries through Magnetohydrodynamic Peristaltic Motion of Hybrid Nanoparticles

This research aims to investigate the efficacy of hybrid nanoparticles in improving magnetohydrodynamic (MHD) peristaltic blood flow in stenotic arteries. Hybrid nanoparticles combining MHD processes and peristaltic motion show promise for increasing blood flow through constricted arteries. To evaluate the impact of nanoparticles on blood flow parameters, researchers use theoretical modelling and analytical solutions. Incorporating copper and aluminium oxide nanoparticles (Cu-Al2O3) into blood, leading to the formation of an ionic solution, is a crucial step in creating a homogeneous hybrid blood suspension. The mathematical model uses approximations of the stenosis and non-dimensional parameters for a mild stenosis scenario to simplify the underlying coupled nonlinear partial differential equations. Analytical solutions for various blood flow parameters such as velocity, temperature, stream function, wall shear stress, Nusselt number, and flow resistance impedance are obtained using the perturbation technique. This study visually analyzes how different physiological variables affect arterial blood flow characteristics. The heat conductivity of blood is an essential aspect of preserving one's sustenance, which is largely determined by the concentration of hybrid nanoparticles. A streamlined pattern depicts the direction of blood flow within an artery. This research demonstrates that the adverse effects of vascular stenosis can be mitigated by using hybrid nanoparticles. In order to aid narrowed arteries, these nanoparticles lessen wall shear stress, boost axial flow speed, and enhance the velocity profile.

Quantile Loss Function Empowered Machine Learning Models for Predicting Carotid Arterial Blood Flow Characteristics

This research presents a novel approach using machine learning models with the quantile loss function to predict blood flow characteristics, specifically the wall shear stress, in the common carotid artery and its bifurcated segments, the internal and external carotid arteries. The dataset for training these models was generated through a numerical model developed for the idealized artery. This model represented blood as an incompressible Newtonian fluid and the artery as an elastic pipe with varying material properties, simulating different flow conditions. The findings of this study revealed that the quantile linear regression model is the most reliable in predicting the target variable, i.e., wall shear stress in the common carotid artery. On the other hand, the quantile gradient boosting algorithm demonstrated exceptional performance in predicting wall shear stress in the bifurcated segments. Through this study, the blood velocity and the wall shear stress in the common carotid artery are identified as the most important features affecting the wall shear stress in the internal carotid artery, while the blood velocity and the blood pressure affected the same in the external carotid artery the most. Furthermore, for a given record of the feature dataset, the study revealed the efficacy of the quantile linear-regression model in capturing a possible prevalence of atherosclerotic conditions in the internal carotid artery. But then, it was not very successful in identifying the same in the external carotid artery. However, due to the use of idealized conditions in the study, these findings need comprehensive clinical verification.

Flow of blood mixed with copper nanoparticles in an inclined overlapping stenosed artery with magnetic field

A literature survey related to nanoparticles reveals that nanofluids are getting more popularity in hematological treatment. Development in this direction motivated us to write a theoretical study on the flow of blood mixed with suspended copper nanoparticles with water as a base fluid in an inclined overlapping stenosed artery under the influence of a magnetic field. The geometry of an overlapping stenosed arterial section is being written mathematically by an appropriate geometric expression. The rheology of the blood is formulated mathematically by coupled partial differential equations. The coupled partial differential equations governing the problem are simplified and solved analytically under mild stenosis assumptions. The expressions for velocity, temperature, pressure droplet, flow resistance, and wall shear stress distribution are obtained in the present analysis. Effects of some emerging physical parameters on arterial blood flow characteristics are shown graphically and discussed briefly for copper nanoparticles.

Femoral Blood Flow During Blood Flow Restriction In Males And Females

Use of blood flow restriction (BFR) during strength training results in an increase in muscle strength and mass when using light loads (20-30% of 1 RM). Only a few studies have reported actual arterial blood flow characteristics during BFR. In addition, research reporting blood flow characteristics in the dominant and non-dominant limb in both males and females is lacking. PURPOSE: This study compared femoral artery occlusion pressure (AOP) and femoral artery blood flow characteristics at different percentages of AOP between both legs in males and females. METHODS: Participants in this study included 31 physically active and healthy males (n=18) and females (n=13) years of age. Blood flow in the superficial femoral artery (SFA) was measured using Doppler ultrasound and BFR was controlled using a Hokanson E20 Rapid Cuff Inflator with a 10 cm cuff placed on the upper thigh. After measuring the AOP of the SFA, blood flow was measured in a random order at 0%, 20%, 40%, 60%, 80%, and 100% of AOP. This was repeated in the opposite leg. Blood flow was recorded in absolute (mL/min) and relative terms (% unoccluded bloodflow). RESULTS: There was significant difference (p<0.008) in the AOP in the dominant leg (234 vs 188 mmHg) and nondominant leg (206 vs 177 mmHg) between males and females, respectively. After accounting for differences in leg circumference (p<0.001), sex remained a significant (p=0.0001) factor in accounting for differences in AOP. The difference in AOP between the dominant and nondominant leg in males (234 vs 206 mmHg) and females (188 vs 177) were not significant (p=0.123). At each of the occlusion pressures (0%, 20%, 40%, 60%, 80%, 100% of AOP), there were no differences in absolute or relative blood flow between males and females. The relationship between SFA blood flow at occlusion pressures between 0 and 100% of the AOP was curvilinear in both males and females. Blood flow at occlusion pressures between 40% and 80% of AOP was relatively constant. CONCLUSIONS: Significant differences in AOP in males and females can be attributed, in part to differences in leg circumference and sex. The curvilinear relationship between blood flow and occlusion pressure indicates that BFR during exercise can be equally effective a lower pressures (40% AOP) as at higher pressures (80% AOP).

Sonographic Association of Uterine Artery Pulsatility Index with Hypertension During Third Trimester of Pregnancy

Background: Hypertension (HTN) in pregnancy is the second most basic reason for maternal death and cause obstetric complications in 5-10% of all pregnancies. HTN directly affects the blood flow of uterine artery. Doppler screening test is a valuable method to do safe and non-invasive detection and has high reliability in the detection of uterine artery blood flow characteristics. Objective: The purpose of the present study is to find association between predictive value of uterine artery pulsatility index in normal and hypertensive pregnancy during third trimester. Methods: A descriptive cross-sectional study was conducted with the sample size of 138 patients by selecting the convenient sampling from Ghurki Trust Teaching Hospital, Lahore. The pulsatility index of uterine artery of all the women with normal singleton pregnancy and hypertensive during third trimester of pregnancy were obtained using Doppler ultrasound. Data was analyzed with the help of Anova .The results were derived by mean, frequency and standard deviation . Results: The significance between groups was 0.002. The mean values of right and left uterine artery pulsatility index of 36 hypertensive patients were 1.40 and 1.41 and standard deviation 0.4 and 0.5 respectively whereas the mean values of right and left uterine artery pulsatility index of 102 normal patients were 0.739 and 0.77 and standard deviation 0.23 and 0.5 respectively Conclusion: Our study concluded that there was an association between uterine atery pulsatility index and hypertension during pregnancy. The uterine artery pulsatiltiy index has increased with hypertension in third trimester of pregnancy. Keywords: Hypertension, Pulsatility Index, Doppler Ultrasound DOI: 10.7176/JHMN/72-07 Publication date: March 31 st 2020

30 Study on blood dynamic viscosity in arteries via CFD

Objectives Blood is a typical non-Newtonian fluid, and poor fluidity of blood is key to the pathogenesis of thrombus. The dynamic viscosity (high blood viscosity) of blood is a key factor in blood vessel embolization, especially cardiovascular and cerebrovascular embolisms. Computational fluid dynamics (CFD) is an efficient method for Newtonian or non-Newtonian fluid flow simulation. The finite volume method (FVM) is also an efficient numerical method for fluid dynamics simulation. This study aimed to investigate blood flow characteristics in arteries, and the dynamic viscosity is taken into account via the non-Newtonian fluids and CFD theory. Methods A series of numerical computations are presented to reproduce the process of blood flowing in arteries using the FVM code CFX. Blood flow simulation will be accelerated using the GPU parallel computation scheme with the CUDA-enabled GPU coprocessor. Results The dynamic viscosity and flow field of blood will be computed and shown by the contours. The velocity, shear strain rate and dynamic viscosity of blood can be calculated and monitored for different ages of people. Conclusions The dynamic viscosity and flow characteristics of blood in arteries can be reproduced using CFD and FVM. The mechanism of blood vessel embolization can be analyzed via the non-Newtonian fluids and CFD theory. Thrombus occurs when the rheology of blood is enhanced. Acknowledgements This research was financially supported by Shaanxi Hundred People Plan Foundation (Grant No. 302-253051601).

METALLIC NANOPARTICLES INFLUENCE ON BLOOD FLOW THROUGH A STENOTIC ARTERY

A model of magnetohydrodynamic blood flow through an artery with a mild stenosis under the influence of metallic nanoparticles is presented. The coupled nonlinear partial differential equations governing the problem are simplified by subject to reasonable modeling and stenosis approximations to obtain analytic expressions for the flow character- istics. The expressions for velocity, temperature, stream function, flow resistance and wall shear stress distribution are obtained in the present analysis. Effects of some emerging phys- ical parameters on arterial blood flow characteristics are shown graphically and discussed briefly under the influence of metallic nano particles (nanofluid model). Finally, stream line patterns illustrating size and number of trapping boluses are introduced and discussed for various imbedded parameters.

Uterine artery blood flow characteristics assessed during oestrus and the early luteal phase of pregnant and non-pregnant bitches

The aim of this study was to measure uterine artery blood velocity daily using Doppler ultrasonography in 10 young and 10 older clinically normal bitches throughout oestrus.Typical arterial waveforms identified in young bitches were characterised by a systolic peak and subsequent flow throughout diastole, whereas in older bitches, flow was sometimes absent in diastole. For 3days immediately prior to ovulation, at the time of declining plasma oestrogen and increasing progesterone concentrations, resistance index (RI) increased, principally associated with decreased diastolic velocity; in some bitches there was absent late diastolic flow during this time. In older bitches, the waveform appearance was more variable, with absent late and early diastolic flow observed in some cases. Mean RI was higher throughout oestrus for older bitches compared with young bitches, although both groups had a similar 3-day duration increase before ovulation. Nine of the young bitches and five of the older bitches became pregnant; litter size was smaller for the older bitches. Non-pregnant bitches: (1) were significantly older; (2) had fewer waveforms with continuous diastolic flow 2days before ovulation; (3) had lower end diastolic velocity, higher RI and fewer waveforms with continuous diastolic flow 2days after ovulation, and (4) had lower plasma progesterone concentrations 5days after ovulation. These are the first detailed observations of uterine artery blood velocity and waveform appearance throughout oestrus in bitches, and this is the first description of a link between impaired diastolic flow and reduced fertility. Assessment of uterine artery velocity could be useful to promote understanding of physiological mechanisms and could also become an important tool to assess potential infertility.

The double‐edged sword of fibronectin in atherosclerosis

Atherosclerosis, the leading cause of death in Westernized countries, derives from a non‐resolving inflammation of the large arteries. A critical step in the initiation of an atherosclerotic plaque is the expansion of intimal space (the area between the endothelial cell (EC) lining and the medial smooth muscle cell layer) in susceptible regions of arteries (Tabas et al, 2007). The disease‐prone locations are largely determined by arterial blood flow characteristics, with branch points and the lesser curvatures of arteries, where the flow is turbulent, being particularly disposed to plaque formation. At these sites, the normally thin intimal space expands with the deposition of extracellular matrix (ECM), which then serves as a sticky surface to trap LDL particles that are constantly crossing the endothelial layer to enter the artery. One reason for this retention is that the apoB100 molecule on the LDL particle has a specific domain that binds tightly to the ECM, and genetic causation studies in a mouse model of atherosclerosis have shown that when this domain is deleted, plaque burden is significantly reduced despite equivalent hyperlipidemia (Skalen et al, 2002). As implied by the ‘Response to Retention’ hypothesis (Tabas et al, 2007), the retained lipoprotein particles set in motion the invasion of the arterial wall by monocytes that quickly become macrophages that engorge themselves on cholesterol and the other lipids to form foam cells. Foam cells not only physically expand the plaque, but by secreting a variety of chemokines and cytokines, they also create and amplify an inflammatory state (Fig 1). Figure 1. Plasma derived FN promotes atherogenesis in mouse models of atherosclerosis. pFN, synthesized in the liver, is deposited in susceptible regions of the arteries and contributes to early atherosclerotic lesion formation and the recruitment of smooth muscle cells that shape the fibrous cap of advanced lesions (upper panel). …

Uterine Vascular Function in a Transgenic Preeclampsia Rat Model

We investigated intrauterine growth restriction, endothelial function, and uterine artery blood flow characteristics in a transgenic preeclampsia rat model with an activated renin-angiotensin system. We compared preeclamptic Sprague-Dawley (SD-PE) rats with normal pregnant Sprague-Dawley and nonpregnant Sprague-Dawley rats. We used transabdominal ultrasound and found that SD-PE rat embryos developed intrauterine growth restriction. Isolated uterine arteries from SD-PE rats incubated with phenylephrine exhibited an increased contractile response, whereas a single high dose of acetylcholine resulted in an impaired vasorelaxation compared with controls. Incremental acetylcholine doses increased relaxation of SD-PE vessels at low acetylcholine doses but caused a paradoxical contraction at higher acetylcholine doses. Indomethacin and a thromboxane-receptor antagonist (SQ 29,548) blocked this effect, suggesting maternal prostanoid-dependent endothelial dysfunction. SD-PE rats had a decreased prostacyclin (6-keto-prostaglandin F1alpha):thromboxane ratio in the serum compared with normal pregnant Sprague-Dawley rats or nonpregnant Sprague-Dawley. Surprisingly, the Doppler resistance index decreased during pregnancy in SD-PE compared with normal pregnant Sprague-Dawley rats, suggesting unimpaired uteroplacental flow in the uterine artery. Umbilical flow was unchanged with absent end-diastolic flow in all of the groups. Renin-angiotensin system activation-induced preeclampsia is associated with altered placentation, modified resistance index, and endothelial dysfunction. A disturbed prostacyclin:thromboxane ratio could be an important mediator.

Proximal pulmonary artery blood flow characteristics in healthy subjects measured in an upright posture using MRI: The effects of exercise and age

To use MRI to quantify blood flow conditions in the proximal pulmonary arteries of healthy children and adults at rest and during exercise in an upright posture. Cine phase-contrast MRI was used to calculate mean flow and reverse flow index (RFI) in the main (MPA), right (RPA), and left (LPA) pulmonary arteries in healthy children and adults in an open-MRI magnet equipped with an upright MRI-compatible ergometer. From rest to exercise (150% resting heart rate), blood flow (liters/minute/m2) increased in the RPA (1.4+/-0.3 vs. 2.5+/-0.4; P<0.001), LPA (1.1+/-0.3 vs. 2.2+/-0.6; P<0.001), and MPA (2.7+/-0.5 vs. 4.9+/-0.5; P<0.001). RFI decreased in the LPA (0.040+/-0.030 vs. 0.017+/-0.018; P<0.02) and MPA (0.025+/-0.024 vs. 0.008+/-0.007; P<0.03). Adults experienced greater retrograde flow in the MPA than the children (0.042+/-0.029 vs. 0.014+/-0.012; P<0.02). It appears that at both rest and during exercise, in children and adults alike, RPA/LPA mean blood flow distribution is predominantly determined by distal vascular resistance, while retrograde flow is affected by proximal pulmonary bifurcation geometry.

Assessment of gestational trophoblastic disease by Doppler ultrasonography

Objectives: To relate uterine artery blood flow characteristics to serum human chorionic gonadotropin (hCG) levels in patients with gestational trophoblastic disease (GTD). Study design: Twenty-one patients with GTD were investigated by serum hCG titers and Doppler ultrasonography of uterine arteries. The relations between the Doppler indices and the serum hCG titers were evaluated by paired- t, Mann–Whitney U tests, and Pearson’s correlation analysis. Results: Significant but weak negative correlations were observed between systole/diastole ( S/ D) ratios, resistance indices (RIs) and pulsatility indices (PIs) and the absolute values of serum hCG levels with correlation coefficients of −0.31, −0.37, and −0.33 ( P<0.05). However, the same Doppler indices had more significant and strong negative correlations with the logarithmic values of the serum hCG levels with correlation coefficients of −0.65, −0.58, and −0.63, respectively ( P<0.01). Five patients who received chemotherapy had significantly lower Doppler indices than those 16 patients with spontaneous regression ( P<0.001). Conclusions: Uterine artery Doppler indices might be used for the surveillance of the patients with GTD.

Assessment of arterial blood flow characteristics in normal and atherosclerotic vessels with the fast Fourier flow method

Assessment of arterial blood flow characteristics in normal and atherosclerotic vessels with the fast Fourier flow method

Arterial blood flow characteristics in central retinal vein occlusion and effects of panretinal photocoagulation treatment: an investigation by colour Doppler imaging

AIMSTo determine whether an increase in vascular resistance in the central retinal and ophthalmic arterial circulations contributes to the development of central retinal vein occlusion (CRVO), or haemodynamic alterations in...

Umbilical Artery Blood Flow Characteristics in Normal Pregnancies

585 pregnant women were investigated with both conventional sonographic examination and color Doppler examination. The cases with intrauterine growth retardation, preeclampsia, twin pregnancies, congenital malformations and diabetes were excluded. The remaining 550 cases (between ages 16 and 40) were investigated in the first trimester and gestational ages were compatible with the last menstrual date. In order to evaluate fetal development, biparietal diameter, femur length, abdominal circumference, and estimated fetal weight were calculated by conventional ultrasonographic method. The application of Doppler ultrasound to the study of fetal umbilical arterial blood flow velocity is a relatively new technique. The failure to obtain useful Doppler signals was about 18-22% with pulse-wave Doppler system. Recently, color Doppler technology solved this problem. We used an ALOKA 680-SSD ultrasonography device and color Doppler ultrasonography technique and recorded umbilical arterial Doppler signals from every case and calculated classical Doppler indices--systolic/diastolic (S/D) ratio, pulsatility index (PI), Pourcelot index or resistive index (RI). Statistical comparisons were made by SPSS program. Correlation coefficient and R2 values between gestational age and other indices were calculated. The aforementioned values were r:-0.79; R2:0.63 0.63; r:-0.71; R2:0.50, r:-0.64; R2:0.41, for S/D, PI, RI, respectively.

Characteristics of blood flow velocity in the hypertensive canine pulmonary artery.

Pulmonary artery blood flow velocity was measured in 15 dogs by a recently developed direct intraluminal pulsed Doppler technique. Changes in velocity characteristics under conditions of experimentally induced hypoxic pulmonary hypertension were observed. Experimental conditions (fractional inspired oxygen concentration = 0.10) produced significant increases in mean pulmonary artery pressure and pulmonary vascular resistance. Overall and maximal negative velocity increased with pulmonary hypertension. Negative velocity occurred predominantly in the posterior half of the pulmonary artery during both control and experimental conditions. With pulmonary hypertension, diastolic negative velocity increased only in the posterior half of the pulmonary artery and systolic negative velocity decreased only in the anterior half. More basic knowledge of pulmonary artery blood flow characteristics may facilitate an informed approach to noninvasive detection of pulmonary hypertension. Direct measurements by this recently developed intraluminal technique will be useful in studying various conditions with altered pulmonary blood flow.

Umbilical Artery Blood Flow Characteristics in Normal and Growth-Retarded Fetuses

Umbilical Artery Blood Flow Characteristics in Normal and Growth-Retarded Fetuses

Umbilical artery blood flow characteristics in normal and growth-retarded fetuses.

Time-velocity waveforms or sonograms obtained by pulsed Doppler ultrasound from the umbilical artery were analysed in a longitudinal study of 15 normal pregnancies. The sonograms from nine fetuses with intrauterine growth retardation were compared qualitatively and had quite different characteristics implying a high distal impedance to blood flow. Methods of analysis capable of differentiating between the normal and abnormal sonograms are described and discussed.