Blood Velocity Research Articles

Close Correlations Between Carotid Arterial Mean Blood Flow Velocity, Body Mass Index, and Temperature in Normal Individuals

Objective: Assessing carotid and radial pulses is an essential sphygmology method in traditional Chinese medicine (TCM). It is believed in TCM and by doctors that pulse force is markedly linked with the physiological state of a human, including body mass index (BMI) and temperature. However, comprehensive analysis elucidating these potential correlations remains undetermined. Therefore, this investigation aimed to assess the association of pulse strength with human metabolism. Materials and Methods: The mean blood flow velocity (MBFV) of the carotid artery and pulse force of 122 healthy adults included in this investigation were assessed using ultrasound and manual palpation. Their thermal texture map was also acquired. Results: No substantial variation was observed in the carotid arterial MBFV among normal individuals (P > 0.05) regardless of body side and gender. However, young individuals had higher blood velocity than middle-aged individuals (P < 0.05). Furthermore, it was identified that MBFV was negatively associated with BMI and torso temperature; however, it was positively linked with hand temperature. Conclusions: This investigation revealed that carotid arterial MBFV could indicate the physical state of humans, including BMI and temperature, and therefore, is valuable for elucidating the effect of TCM on yin–yang. The data validated some TCM beliefs and supported the implementation of sphygmology in TCM.

Cerebrovascular pulsatility index is higher in chronic kidney disease.

Patients with chronic kidney disease (CKD) are more likely to die of cardiovascular diseases, including cerebrovascular disease, than to progress to end-stage kidney disease. Cerebrovascular dysfunction, characterized by reduced cerebrovascular reactivity, cerebral hypoperfusion, and increased pulsatile flow within the brain, precedes the onset of dementia and is linked to cognitive dysfunction. However, whether impaired cerebrovascular function is present in non-dialysis dependent CKD is largely unknown. Using transcranial Doppler, we compared middle cerebral artery (MCA) blood velocity response to hypercapnia (normalized for blood pressure and end-tidal CO2 ; a measure of cerebrovascular reactivity) and MCA pulsatility index (PI; a measure of cerebrovascular stiffness) in patients with stage 3-4 CKD vs. age-matched healthy controls. We also administered the NIH cognitive toolbox (cognitive function), measured carotid-femoral pulse-wave velocity (PWV; aortic stiffness), and assessed ex vivo nitric oxide (NO) and reactive oxygen species (ROS) production from human brain endothelial cells incubated with serum obtained from study participants. MCA PI was higher in patients with CKD vs. controls; however, normalized MCA blood velocity response to hypercapnia did not differ between groups. Similar results were observed in a validation cohort of midlife and older adults divided by the median estimated glomerular filtration rate (eGFR). MCA PI was associated with greater large-elastic artery stiffness (carotid-femoral PWV), worse executive function (trails B time), lower eGFR, and higher ex vivo ROS production. These data suggest that impaired kidney function is associated with greater cerebrovascular stiffness, which may contribute to the known increased risk for cognitive impairment in patients with CKD.

Colour Doppler and Adverse Perinatal Outcomes in Pregnancies with Foetal Growth Restriction: A Prospective Longitudinal Study

Introduction: Foetal Growth Restriction (FGR) accounts for a significant proportion of perinatal morbidity and mortality. The study was done to diagnose the foetuses “at risk”, so that timely intervention could prevent perinatal morbidity and mortality, as FGR foetuses with deranged velocimetry of Uterine Artery (UA), Umbilical Artery (UMA), Middle Cerebral Arteries (MCA) are associated with high perinatal morbidity and mortality. Aim: To evaluate the usefulness of blood flow velocimetry of UA, UMA, and MCA as well as a Cerebroplacental Ratio (CPR) on colour doppler and their prediction of adverse perinatal outcome. Materials and Methods: This was a prospective longitudinal study done in the Department of Obstetrics and Gynaecology, Government Medical College and Rajindra Hospital, Patiala, Punjab, India from October 2021 to March 2022. The study was conducted among 200 antenatal patients, who had a singleton pregnancy, irrespective of age and parity and had FGR foetuses. Blood flow velocities in the UA, UMA, MCA, and CPR were measured. Patients were divided into four groups with 50 patients in each group. Group I included FGR foetuses with normal blood velocities, group II included FGR foetuses with abnormal UA velocimetry, group III included FGR foetuses with abnormal UMA and MCA velocimetry and group IV included FGR foetuses with abnormal CPR. Adverse perinatal outcomes in the form of Respiratory Distress Syndrome (RDS), prematurity, Appearance, Pulse, Grimace, Activity and Respiration (APGAR) <7 at 5 minutes, admission to Neonatal Intensive Care Unit (NICU), and perinatal mortality were assessed in relation to these doppler blood flow patterns. Categorical variables were analysed with the help of Chi-square test and Fisher-exact Test. Continuous variables were analysed with ANOVA when data were normally distributed otherwise Kruskal Wallis H test was used. Results: The mean birth weight was 2432±423, 2209±329, 2100±223 and 1329±403 grams in Groups-I, II, III, and IV (p-value of <0.001.) The mean gestational age was 38.1±2.3, 37.3±3.2, 36±3.6 and 33.1±3.1 weeks in groups I, II, III, and IV (p-value of <0.001). Perinatal morbidity in the form of RDS and prematurity were compared among four groups with 0, 3 (6%), 17 (34%), and 39 (78%) in Groups I, II, III, and IV (p-value of <0.001). APGAR score <7 at 5 minutes was 0, 2 (4%), 9 (18%), and 13 (26%) in groups 1, II, III, and IV (p-value of <0.001). A total of 6 (12%), 16 (32%), 37 (74%) and 46 (92%) C-sections were performed in group I, II, III and IV, respectively, p-value of <0.001. Maternal mortality of 1 (2%) in group III and 2 (4%) was observed in group IV. But no maternal death was there in group I and II. Conclusion: The adverse perinatal outcomes were seen with changes in Pulsatility Index (PI) value of UA, UMA, MCA. But the patients with a deranged CPR ratio had got worse perinatal outcomes than either deranged MCA, PI or UMA PI alone. Hence, doppler ultrasound especially CPR ratio should be an integral component of routine evaluation of FGR pregnancies, as it helps in obstetrical surveillance and management, and thereby improving adverse perinatal outcomes.

Altered Right Portal and Umbilical Vein Doppler Parameters in Fetal Macrosomia Resulting from Pregestational andGestational Diabetic Mothers: A Prospective Case-Control Study

Objective: To evaluate the blood flow of the umbilical vein and right portal vein in macrosomic fetuses of diabetic mothers and investigate the effect of maternal insulin treatment on these blood flows. Material and Methods: This prospective case-control study was conducted between March 2019 and December 2019. Fetuses of the 49 pregestational and gestational diabetic mothers who had an abdominal circumference percentile above 97% were evaluated as macrosomic and formed the study group. The study group was divided into two subgroups: patients treated with insulin and those who did not. In the control group, 48 non-diabetic pregnant women with matched gestational weeks whose fetuses are at the 10-90% percentile were included. Time-averaged maximum blood velocity (TAMXV) values of the right portal vein and the free loop of the umbilical vein were measured. Results: The median right portal vein TAMXV value and umbilical vein TAMXV value were found to be significantly higher in diabetic pregnancies (16.25 cm/s, and 15.28 cm/s, respectively) than in the control group (12.76 cm/s, and 13.38 cm/s, respectively, p<0.001). Umbilical and right portal vein flows were similar in macrosomic fetuses of diabetic mothers who were treated with insulin or those who did not. While umbilical vein flow in macrosomic fetuses increased as the gestational age progressed (p=0.028), it was observed steadily in normally growing fetuses. Conclusion: The umbilical and right portal vein flows are higher in macrosomic fetuses of diabetic mothers than in appropriately grown fetuses. Maternal insulin treatment does not affect fetal umbilical vein and right portal vein blood flow in macrosomic fetuses.

Mathematical Analysis of Hemodynamic Parameters of Blood Flow in an Artery

In blood rheology we study volume flow rate, blood pressure, velocity, viscosity and shear stress of blood. Cross-sectional area plays an important role for smooth flow of the blood. But some other parameter like composition of blood, length of vessel also affects in the flow rate and pressure of blood. Velocity and volume flow rate are derived by using Poiseuille’s equation.This work presents a mathematical model of blood flow that was created using the N-S equations and computer simulation. Graphs are used to analyze the results.

Cerebrovascular Function in Migraine Patients during, their Interictal Period, Compared to Normal Healthy Controls

Background: Migraine is a debilitating neurovascular disorder which primarily impacts the working age population. The aim of the study was to determine if transient hemodynamic alterations during each migraine attack translates into cerebrovascular alterations, during migraineurs interictal period. A secondary hypothesis was to determine if there was any relationship between vascular hemodynamics and either the severity or frequency of migraine attacks.Methods: We recruited 29 volunteers: 13 migraineurs (mean age 28±8.8 years; 12 female and 1 male) and 16 age-matched controls (mean age 26.6±6.9; 9 female and 7 male). Volunteers were classified as migraine sufferer or not (control group). All individuals underwent a detailed ophthalmic examination by a qualified optometrist and a Migraine Disability Assessment. Cerebral blood velocity measurements for the Middle Cerebral Artery (MCA) and Vertebral Artery (VA) were obtained using Colour Doppler Imaging using the Hitachi Aloka Noblus ultrasound system. The investigators were blind to the migraine diagnosis.Results: During their interictal period migraineurs appear to have no significant difference in any hemodynamic parameter, for either their MCA and VA, when compared to normal healthy controls. Neither was a significant relationship between Migraine Disability Assessment Scores and any vascular parameter reported.Conclusion: This study found nil cerebrovascular alterations which could be measured in migraineurs compared to normal healthy controls, during their interictal period.

Convective Flow of Blood through a Constricted Cylinder and the Effect of Cholesterol Growth Rate on the Motion in the Presence of a Magnetic Field

An inflammatory disease resulting in the pathological constriction of the intima and media of the arterial system, such as the aorta, causes symptoms like stroke, heart attack, or angina; This research investigates the convective flow of blood through a constricted cylinder and the effect of cholesterol growth rate on the motion in the presence of a magnetic field by transforming the problem into a system of time-dependent partial differential equations. The governing partial differential equations (PDEs) were transformed into dimensionless ordinary differential equations (ODEs) and solved using the Laplace method. After obtaining the analytical solution, Wolfram Mathematica was used to perform the numerical computation where the various physical parameters such as Soret number, radiation number, solutal Grashof number, Schmidt number, and Prandtl number were varied to their impact studied. The study discovered that increasing the Soret number causes an increase in blood velocity, whereas decreasing the Solutal Grashof number decreases blood velocity. Furthermore, an increase in radiation parameter increases the blood velocity, but a Soret number increase results in a decrease in the concentration of cholesterol in the fluid, a Schmidt number, and oscillatory frequency increase, causing the temperature to decrease. This research is useful for clinicians and mathematical modellers who are trying to understand the flow of cholesterol saturated fluid in the human vascular system and how best to proffer analytical and numerical solutions in synergy with laboratory investigation.

COVID-19 hemodynamic and thrombotic effect on the eye microcirculation after hospitalization: A quantitative case-control study.

To quantify the hemodynamic and thrombotic effect of COVID-19 on the eye microcirculation of patients with thromboprophylaxis, shortly after hospital discharge. This case-control study included 17 COVID-19 survivors (named "COVID-19 Group") and 17 healthy volunteers (named "Control Group"). Axial blood velocity (Vax) and percentage of occluded vessels (POV) were quantified by Conjunctival Video Capillaroscopy (CVC). Microvessels were identified and classified as "capillaries" (CAP), "postcapillary venules of size 1" (PC1), and "postcapillary venules of size 2" (PC2). The COVID-19 Group did not differ significantly in basic demographics from the Control Group. In the COVID-19 Group, there was a statistically significant (p < 0.001) reduction of Vax (39%, 49% and 47%, for CAP, PC1, and PC2, respectively) in comparison to the Control Group and a sizeable (p < 0.001) increase of POV (600%) in comparison to the Control Group. COVID-19 not only reduces significantly axial blood velocity in the capillaries and postcapillary venules of the eye but has also a devastating effect on microthrombosis (POV) despite thromboprophylaxis treatment. This gives a possible explanation for long COVID and a hint about the existence of a possibly unknown coagulation factor.

Hemostatic Complications During Neonatal Extracorporeal Membrane Oxygenation: Roller Pump and Centrifugal Pump Driven Circuits.

Recently three different neonatal extracorporeal membrane oxygenation (ECMO) circuits have been employed in our clinic. These circuits were compared for clotting and bleeding complications. Initially, we used an ECMO circuit containing a roller pump and venous bladder without severe complications. Manufacturing of circuit components was discontinued, necessitating the replacement of this circuit by a circuit with a centrifugal pump with 3/8 inch inlet and outlet. Acute increase of oxygenator resistance requiring emergency changeout became unexpectedly a regularly occurring complication. The increase in resistance was suspected to be caused by oxygenator clotting, although oxygenator function was preserved. To prevent this complication, we changed to a levitating centrifugal pump with 1/4 inch inlet and outlet, after which no oxygenator malfunction has been observed. Macroscopic and electron microscopic analysis demonstrates that small clots are formed within the circuit, presumably in or near the centrifugal pump, which are transported to the oxygenator and clog up the hollow fiber layer at the inlet side, barely penetrating the oxygenator beyond this first layer. Our results suggest that low blood velocities accompanied with recirculation of blood within or near the centrifugal pump and/or heat generation within the pump could contribute to the formation of these clots.

The contribution of intracranial pressure to human dynamic cerebral autoregulation after acute brain injury.

Cerebral perfusion pressure (CPP) is normally expressed by the difference between mean arterial blood pressure (MAP) and intracranial pressure (ICP) but comparison of the separate contributions of MAP and ICP to human cerebral blood flow autoregulation has not been reported. In ABI patients, internal jugular vein compression (IJVC) was performed for 60 s. Dynamic cerebral autoregulation (dCA) was assessed in recordings of middle cerebral artery blood velocity (MCAv, transcranial Doppler), and invasive measurements of MAP and ICP. Patients were separated according to injury severity as having whole/undamaged skull, large fractures or craniotomies, or following decompressive craniectomy. Glasgow coma score was not different for the three groups. IJVC induced changes in MCAv, MAP, ICP, and CPP in all three groups. The MCAv response to step changes in MAP and ICP expressed the dCA response to these two inputs, and was quantified with the autoregulation index (ARI). In 85 patients, ARI was lower for the ICP input as compared to the MAP input (2.25 ± 2.46 vs 3.39 ± 2.28; p<0.0001), and particularly depressed in the DC group (n=24, 0.35 ± 0.62 vs 2.21 ± 1.96; p<0.0005). In patients with ABI, the dCA response to changes in ICP is less efficient than corresponding responses to MAP changes. These results should be taken into consideration in studies aimed to optimize dCA by manipulation of CPP in neurocritical patients.

The impact of rotor configurations on hemodynamic features, hemocompatibility and dynamic balance of the centrifugal blood pump: A numerical study.

To investigate the effect of rotor design configuration on hemodynamic features, hemocompatibility and dynamic balance of blood pumps. Computational fluid dynamics was employed to investigate the effects of rotor type (closed impeller, semi-open impeller), clearance height and back vanes on blood pump performance. In particular, the Eulerian hemolysis model based on a power-law function and the Lagrangian thrombus model with integrated stress accumulation and residence time were applied to evaluate the hemocompatibility of the blood pump. This study shows that compared to the closed impeller, the semi-open impeller can improve hemolysis at a slight sacrifice in head pressure, but increase the risk of thrombogenic potential and disrupt rotor dynamic balance. For the semi-open impeller, the pressure head, hemolysis, and axial thrust of the blood pump decrease with increasing front clearance, and the risk of thrombosis increases first and then decreases with increasing front clearance. Variations in back clearance have little effect on pressure head, but larger on back clearance, worsens hemolysis, thrombogenic potential and rotor dynamic balance. The employment of back vanes has little effect on the pressure head. All back vanes configurations have an increased risk of hemolysis in the blood pump but are beneficial for the improvement of the rotor dynamic balance of the blood pump. Reasonable back vanes configuration (higher height, wider width, longer length and more number) decreases the flow separation, increases the velocity of blood in the back clearance, and reduces the risk of blood pooling and thrombosis. It was also found that hemolysis index (HI) was highly negatively correlated with pressure difference between the top and back clearances (r=-.87), and thrombogenic potential was positively correlated with pressure difference between the top and back clearances (r=.71). This study found that rotor type, clearance height, and back vanes significantly affect the hydraulic performance, hemocompatibility and rotor dynamic balance of centrifugal blood pumps through secondary flow. These parameters should be carefully selected when designing and optimizing centrifugal blood pumps for improving the blood pump clinical outcomes.

Cerebral vascular function following the acute consumption of caffeinated artificially- and sugar sweetened soft drinks in healthy adults.

Chronic consumption of sugar- and artificially-sweetened beverages (SSB and ASB) are associated with an increased risk of stroke but it is unclear how acute consumption influences cerebral vascular function. Purpose: We hypothesized that: (1) acute consumption of SSB and ASB would augment dynamic cerebral autoregulation (dCA) and attenuate cerebral vascular reactivity to hypercapnia (CVRCO2) compared to water; and (2) dCA and CVRCO2 would be attenuated with SSB compared to ASB and water. Methods: Twelve healthy adults (age: 23 ± 2 years, four females) completed three randomized trials where they drank 500 ml of water, SSB (Mountain Dew®), or ASB (Diet Mountain Dew®). We measured mean arterial pressure (MAP), middle and posterior cerebral artery blood velocities (MCAv and PCAv), and end-tidal CO2 tension (PETCO2). Cerebral vascular conductance was calculated as cerebral artery blood velocity/MAP (MCAc and PCAc). Twenty min after consumption, participants completed a 5 min baseline, and in a counterbalanced order, a CVRCO2 test (3%, 5%, and 7% CO2 in 3 min stages) and a dCA test (squat-stand tests at 0.10 Hz and 0.05 Hz for 5 min each) separated by 10 min. CVRCO2 was calculated as the slope of the linear regression lines of MCAv and PCAv vs. PETCO2. dCA was assessed in the MCA using transfer function analysis. Coherence, gain, and phase were determined in the low frequency (LF; 0.07-0.2 Hz) and very low frequency (VLF; 0.02-0.07 Hz). Results: MCAv and MCAc were lower after SSB (54.11 ± 12.28 cm/s, 0.58 ± 0.15 cm/s/mmHg) and ASB (51.07 ± 9.35 cm/s, 0.52 ± 1.0 cm/s/mmHg) vs. water (62.73 ± 12.96 cm/s, 0.67 ± 0.11 cm/s/mmHg; all P < 0.035), respectively. PCAc was also lower with the ASB compared to water (P = 0.007). MCA CVRCO2 was lower following ASB (1.55 ± 0.38 cm/s/mmHg) vs. water (2.00 ± 0.57 cm/s/mmHg; P = 0.011) but not after SSB (1.90 ± 0.67 cm/s/mmHg; P = 0.593). PCA CVRCO2 did not differ between beverages (P > 0.853). There were no differences between beverages for coherence (P ≥ 0.295), gain (P ≥ 0.058), or phase (P ≥ 0.084) for either frequency. Discussion: Acute consumption of caffeinated SSB and ASB resulted in lower intracranial artery blood velocity and conductance but had a minimal effect on cerebral vascular function as only MCA CVRCO2 was altered with the ASB compared to water.

THE EFFECT OF SHORT DURATION BED REST AND TYPE 2 DIABETES MELLITUS ON ARTERIAL STRUCTURE AND FUNCTION IN OLDER ADULTS

Abstract Type 2 diabetes mellitus (T2DM) and inactivity individually accelerate changes related to vascular aging. These changes increase cardiovascular risk and contribute to morbidity and mortality in the elderly. It is unknown if T2DM and bed rest have an additive, deleterious effect on vascular structure and function in older adults. The objective of this study is to determine the magnitude of the effect of bed rest on vascular structure in older adults with T2DM compared to healthy controls and determine if resistance exercise is protective of this effect. So far, we have recruited T2DM (n=9) and healthy control (n=17) subjects (age: 67.0 ± 6.7 years) to undergo five days of bed rest. During bed rest, subjects were randomized to receive intensive bedside resistance exercise physical therapy or standard of care in-bed passive physical therapy. On bed rest days 1 and 5, popliteal artery diameter, area, blood velocity, and blood flow were measured using Doppler ultrasonography. Our preliminary data show that the T2DM, non-exercise group had significantly greater decreases in popliteal artery diameter (-0.59 mm ± 0.18) than the control, non-exercise group (-0.17 mm ± 0.11). Resistance exercise did not prevent artery size changes in either controls or T2DM. Resistance exercise showed a trend in preventing blood velocity and flow reduction in both T2DM and control groups. These preliminary data suggest that older adults with T2DM had greater structural popliteal artery changes compared to controls. Resistance exercise appears to help maintain blood flow by maintaining/increasing popliteal artery blood velocity, but not size.

TILT TEST TOLERANCE AFTER TWO-WEEKS BED REST IN OLDER ADULTS IS NOT PROTECTED BY DAILY AEROBIC AND RESISTANCE EXERCISE

Abstract Bed rest is associated with increased risk of orthostatic intolerance on return to upright posture and, at least in young adults, regular exercise during bed rest is proposed as protective. 22 older adults (55-65 years, half women) participated in a randomized trial with 14-days of continuous 6-degree head-down bed rest. Half completed 60 min/day of aerobic and high-intensity interval cycling plus resistance exercises (Ex) while the other half were control (Con). A passive 80-degree head-up tilt (HUT) to a maximum of 15-min assessed orthostatic tolerance while cardio- and cerebrovascular responses were monitored to a pre-syncopal level of systolic blood pressure &amp;lt; 90 mmHg. In pre-bed rest baseline, all but 3 women (Ex) completed 15-min HUT. After 14-days bed rest, only 3 men (1 Ex) and 1 woman (Ex) completed 15-min with no differences in tolerance between men and women or Ex and Con. Vasovagal syncope presented in 5 participants (2 M-Con, 1 M-Ex, 1 F-Con, 1 F-Ex), most other non-finishers had progressive reduction in stroke volume without adequate vasoconstriction. Reductions in cerebral blood velocity measured during HUT by Doppler ultrasound revealed strong linear relationships to both end-tidal PCO2 and mean arterial pressure across all participants. These data indicate that neither older men nor older women were protected from orthostatic intolerance by 60-min per day exercise including high-intensity interval training. These data contrast with previous findings in younger adults in controlled trials of bed rest pointing to the need for greater understanding of mechanisms regulating blood pressure and brain blood flow.

Imaging Cerebral Arteries Tortuosity and Velocities by Transcranial Doppler Ultrasound Is a Reliable Assessment of Brain Aneurysm in Mouse Models.

During the past few decades, several pathophysiological processes contributing to intracranial aneurysm (IA) rupture have been identified, including irregular IA shape, altered hemodynamic stress within the IA, and vessel wall inflammation. The use of preclinical models of IA and imaging tools is paramount to better understand the underlying disease mechanisms. We used 2 established mouse models of IA, and we analyzed the progression of the IA by magnetic resonance imaging, transcranial Doppler, and histology. In both models of IA, we observed, by transcranial Doppler, a significant decrease of the blood velocities and wall shear stress of the internal carotid arteries. We also observed the formation of tortuous arteries in both models that were correlated with the presence of an aneurysm as confirmed by magnetic resonance imaging and histology. A high grade of tortuosity is associated with a significant decrease of the mean blood flow velocities and a greater artery dilation. Transcranial Doppler is a robust and convenient imaging method to evaluate the progression of IA. Detection of decreased blood flow velocities and increased tortuosity can be used as reliable indicators of IA.

Respiratory training in older women: Unravelling central and peripheral hemodynamic slow oscillatory patterns

We hypothesized that inspiratory muscle training (IMT) increases the respiratory-induced low-frequency oscillations of mean blood pressure (MBP) and middle cerebral artery blood velocity (MCAv), upregulating cerebrovascular function in older women. Firstly, participants were recorded with free-breathing (FB) and then breathed at a slow-paced frequency (0.1 Hz; DB test) supported by sonorous metronome feedback. Blood pressure was recorded using finger photoplethysmography method, ECG, and respiration using a thoracic belt. To obtain the MCAv a transcranial ultrasound Doppler device was used. Spectral analysis of MBP, R-R intervals, and mean MCAv time series was obtained by an autoregressive model. The transfer function analysis (TFA) was employed to calculate the coherence, gain, and phase. After that, older women were enrolled in a randomized controlled protocol, the IMT-group (n = 8; 64 ± 3 years-old) performed IMT at 50 % of maximal inspiratory pressure (MIP), and Sham-group, a placebo training at 5 % MIP (Sham-group; n = 6; 66 ± 3 years-old). Participants breathed against an inspiratory resistance twice a day for 4-weeks. DB test is repeated post IMT and Sham interventions. IMT-group, compared to Sham-group, augmented tidal volume responses to DB (Sham-group 1.03 ± 0.41 vs. IMT-group 1.61 ± 0.56 L; p = 0.04), increased respiratory-induced MBP (Sham-group 26.37 ± 4.46 vs. IMT-group 48.21 ± 3.15 mmHg2; p = 0.04) and MCAv (Sham-group 14.16 ± 31.26 vs. IMT-group 79.90 ± 21.76 cm2s−2; p = 0.03) slow oscillations, and reduced TFA gain (Sham-group 2.46 ± 1.32 vs. IMT-group 1.78 ± 1.30 cm·s−1.mmHg−1; p = 0.01). Our findings suggest that IMT increases the respiratory-induced oscillations in MBP and MCAv signals and reduces TFA gain. It seems compatible with an improved dynamic cerebrovascular regulation following IMT in older women.

Analytical Procedure for the Flow of a Carreau-Yasuda Fluid Through the Diseased Tapered Inclined Artery Subject to Heat Transfer and Chemical Reactions

This paper demonstrates the implications of heat transfer and chemical reactions by considering the flow of a Carreau-Yasuda fluid through the diseased tapered inclined artery. The analysis has performed on the artery with mild stenosis. The analytical solution has been obtained using the perturbation method due to its low Weissenberg number to get the blood velocity, the wall shear stress distribution, the temperature, the concentration, the resistance impedance and the stream function. The critical results in this study have depicted that the blood velocity for dilatant fluid is higher than that in viscous and pseudoplastic fluids in the core region of the artery. The value of blood velocity through a Newtonian fluid is extraordinarily lower than that through a Carreau-Yasuda fluid at the core region of the artery. The magnitude of blood velocity across the vertical artery is higher than those in the inclined and horizontal arteries inside the core region of the artery. The wall shear stress distributions are higher in the case of stenosis (diseased artery) than in no stenosis (healthy artery). The temperature transmission for the Carreau fluid is higher than that for the Carreau-Yasuda fluid. The flow resistance progressively increases as the depth of the stenosis increases. The size of the trapping bolus gradually increases, shifting toward the right at the diverging tapering artery, and it gradually increases, moving toward the left at the converging tapering artery. Finally, the streamlines are noticeably more comprehensive along the vertical artery and are higher than those in the inclined and horizontal arteries.

Axial Wall Displacement at the Common Carotid Artery is Associated With the Lamb Waves

Abstract As compared with its radial wall displacement, axial wall displacement at the common carotid artery (CCA) carries independent clinical values, but its physical mechanisms are unclear. This study aims to investigate whether axial wall displacement at the CCA is solely from Young waves. A pulse wave propagation theory is utilized to identify two types of waves, Young waves, and Lamb waves, in an artery, and identifies two sources for axial wall displacement, wall shear stress and radial wall displacement gradient with a factor of the difference between axial and circumferential initial tension, which reveals the influence of axial initial tension on the waveform of axial wall displacement. Theoretical expressions are derived for calculating the waveforms of axial wall displacement and its two sources in the Young waves. With the measured pulsatile pressure and blood velocity at the CA of three healthy adults as the inputs, the waveforms of axial wall displacement in the Young waves are calculated at different values of axial initial tension and are found to greatly differ from their measured counterparts. As such, the Lamb waves may contribute to axial wall displacement at the CCA and the associated physical and physiological implications are discussed. Given the clinical values of axial wall displacement at the CCA, the Lamb waves may play a non-negligible role in determining arterial health and needs to be further studied for a comprehensive assessment of arterial wall mechanics.

Association between brachial artery peak systolic velocity and ipsilateral radio-cephalic arteriovenous fistula maturation.

To evaluate the association between brachial artery blood velocity by color Doppler flow imaging (CDFI) and primary maturation of radio-cephalic autologous arteriovenous fistula (RC-AVF). Clinical data from patients who underwent end-to-side cephalic-radial anastomosis were collected from December 2015 to December 2020. The anastomosis diameter (mm), blood velocity (cm/s), and brachial artery diameters (mm) 7 cm proximal to the elbow pre- and postoperation were measured by GE LOGIC-E9 ultrasound. The AVF was mature if it could be cannulated successfully and the blood flow was >200 ml/min during dialysis. A total of 197 patients were included in our statistical analysis. A total of 163 patients had mature AVFs, and 34 patients had poor maturity (assisted and failed maturation). There were no significant differences in the clinical characteristics, peak systolic velocity (PSV) of the brachial artery, diameter of the radial artery or cephalic vein measured by CDFI preoperatively. The diameter of the brachial artery (5.41 ± 0.77 vs 4.89 ± 0.90, p = 0.00) and the fistula anastomosis (2.79 ± 0.78 vs 2.45 ± 0.85, p = 0.02) and PSV of the brachial artery (123.58 ± 37.11 vs 89.63 ± 28.31, p = 0.00) in the mature group were higher than those in the immature group. Brachial artery PSV and increased brachial artery PSV could be used to detect RC-AVF maturation in the early stage.

Abdominal and Peripheral Tissue Oxygen Supply during Selective Lower Body Perfusion for the Surgical Repair of Congenital Heart Disease: A Pilot Study.

Lower body perfusion (LBP) may be a strategy for maintaining organ perfusion during congenital heart disease surgery. It is hypothesized that renal and lower limb oxygen supply during LBP is superior to off-pump surgery and comparable to that of a standard cardiopulmonary bypass (CPB). in this prospective single-center study, patients aged &lt;1 year were recruited if they were scheduled for a correction of aortic arch anomalies using antegrade cerebral perfusion and LBP (group 1), a repair of coarctation during aortic cross-clamping (group 2), or surgery under whole-body CPB (group 3). Renal (prefix "r") and peripheral (prefix "p") oxygen saturation (SO2), hemoglobin amount (Hb), blood velocity (Velo), and blood flow (Flow) were measured noninvasively. A total of 23 patients were included (group 1, n = 9; group 2, n = 5; group 3, n = 9). Compared to the baseline values, rSO2 and pSO2 decreased significantly in group 2 compared to groups 1 and 3. Conversely, rHB significantly increased in group 2 compared to groups 1 and 3, reflecting abdominal venous stasis. Compared to group 3, group 1 showed a significantly lower pFlow during CPB; however, rFlow, pFlow, and pVelo did not differ. according to these observations, LBP results in an improved renal oxygen supply compared to off-pump surgery and may prove to be a promising alternative to conventional CPB.