Brachial Artery Flow-mediated Dilation Research Articles

A study of the relationship between brachial artery vasodilation and platelet/lymphocyte ratio in diabetic patients with coronary atherosclerosis.

To investigate the correlation between brachial artery flow-mediated endothelium-dependent dilation (FMD) and platelet-lymphocyte ratio (PLR) in peripheral blood and coronary atherosclerosis in diabetic patients. Seventy-five diabetic patients aged 62 ± 9 years, 68% male and 32% female, who underwent brachial artery endothelial function test and coronary CT scan were collected. Coronary artery calcification (CAC) was observed to assess the presence of coronary atherosclerosis, and high-resolution extravascular ultrasound was used to detect FMD. Platelet count and lymphocyte count were recorded by routine blood tests, and PLR was calculated for each study subject. Statistical methods were used to verify the association of FMD and PLR with CAC assessed by CT, respectively. Patients with coronary atherosclerosis had decreased FMD and increased PLR compared with patients with normal coronary arteries. Univariate logistic regression analysis showed that CAC score was significantly associated with both FMD (odds ratio: 0.167; 95% confidence interval: 0.049-0.565; p = 0.002) and PLR (odds ratio: 0.127; 95% confidence interval: 0.033-0.484; p = 0.001) at FMD < 5.1% or PLR > 130. The area under the ROC curve of FMD and PLR alone was 0.760 and 0.763, respectively. In addition, combined diagnosis of FMD and PLR showed the highest area under the ROC curve (0.830). FMD combined with PLR is expected to be a precise diagnostic modality for coronary artery calcification in diabetic patients.

A nomogram based on endothelial function and conventional risk factors predicts coronary artery disease in hypertensives

BackgroundThere is currently a lack of a precise, concise, and practical clinical prediction model for predicting coronary artery disease (CAD) in patients with essential hypertension (EH). This study aimed to construct a nomogram to predict CAD in patients with EH based on flow-mediated dilation (FMD) of brachial artery and traditional risk factors.MethodsClinical data of 1752 patients with EH were retrospectively collected. High-resolution vascular ultrasound was used to detect FMD in all patients at the Fujian Hypertension Research Institute, China. Patients were divided into two groups, i.e. training group (n = 1204, from August 2000 to December 2013) and validation group (n = 548, from January 2014 to May 2016) according to the time of enrollment. Independent predictors of CAD were analyzed by multivariable logistic regression in the training group, and a nomogram was constructed accordingly. Finally, we evaluated the discrimination, calibration, and clinical applicability of the model using the area under curve (AUC) of receiver operating characteristic analysis, calibration curve combined with Hosmer-Lemeshow test, and decision curve, respectively.ResultsThere were 263 (21.8%) cases of EH combined with CAD in the training group. Multivariate logistic regression showed that FMD, age, duration of EH, waist circumference, and diabetes mellitus were independent influencing factors for CAD in EH patients. Smoking which was close to statistical significance (P = 0.062) was also included in the regression model to increase the accuracy. Ultimately, the nomogram for predicting CAD in EH patients was constructed according to above predictors after proper transformation. The AUC values of the training group and the validation group were 0.799 (95%CI 0.770–0.829) and 0.836 (95%CI 0.787–0.886), respectively. Calibration curve and Hosmer-Lemeshow test showed that the model had good calibration (training group: χ2 = 0.55, P = 0.759; validation group: χ2 = 1.62, P = 0.446). The decision curve also verified the clinical applicability of the nomogram.ConclusionThe nomogram based on FMD and traditional risk factors (age, duration of EH disease, smoking, waist circumference and diabetes mellitus) can predict CAD high-risk group among patients with EH.

Effectiveness of high intensity interval training on cardiorespiratory fitness and endothelial function in type 2 diabetes: A systematic review

Type 2 diabetes mellitus (T2DM) is a chronic metabolic syndrome characterized by insulin resistance and hyperglycemia that may lead to endothelial dysfunction, reduced functional capacity and exercise intolerance. Regular aerobic exercise has been promoted as the most beneficial non-pharmacological treatment of cardiovascular diseases. High intensity interval training (HIIT) seems to be superior than moderate-intensity continuous training (MICT) in cardiovascular diseases by improving brachial artery flow-mediated dilation (FMD) and cardiorespiratory fitness to a greater extent. However, the beneficial effects of HIIT in patients with T2DM still remain under investigation and number of studies is limited. To evaluate the effectiveness of high intensity interval training on cardiorespiratory fitness and endothelial function in patients with T2DM. We performed a search on PubMed, PEDro and CINAHL databases, selecting papers published between December 2012 and December 2022 and identified published randomized controlled trials (RCTs) in the English language that included community or outpatient exercise training programs in patients with T2DM. RCTs were assessed for methodological rigor and risk of bias via the Physiotherapy Evidence Database (PEDro). The primary outcome was peak VO2 and the secondary outcome was endothelial function assessed either by FMD or other indices of microcirculation. Twelve studies were included in our systematic review. The 12 RCTs resulted in 661 participants in total. HIIT was performed in 310 patients (46.8%), MICT to 271 and the rest 80 belonged to the control group. Peak VO2 increased in 10 out of 12 studies after HIIT. Ten studies compared HIIT with other exercise regimens (MICT or strength endurance) and 4 of them demonstrated additional beneficial effects of HIIT over MICT or other exercise regimens. Moreover, 4 studies explored the effects of HIIT on endothelial function and FMD in T2DM patients. In 2 of them, HIIT further improved endothelial function compared to MICT and/or the control group while in the rest 2 studies no differences between HIIT and MICT were observed. Regular aerobic exercise training has beneficial effects on cardiorespiratory fitness and endothelial function in T2DM patients. HIIT may be superior by improving these parameters to a greater extent than MICT.

Evidence of Neurovascular Water Exchange and Endothelial Vascular Dysfunction in Schizophrenia: An Exploratory Study.

Mounting evidence supports cerebrovascular contributions to schizophrenia spectrum disorder (SSD) but with unknown mechanisms. The blood-brain barrier (BBB) is at the nexus of neural-vascular exchanges, tasked with regulating cerebral homeostasis. BBB abnormalities in SSD, if any, are likely more subtle compared to typical neurological insults and imaging measures that assess large molecule BBB leakage in major neurological events may not be sensitive enough to directly examine BBB abnormalities in SSD. We tested the hypothesis that neurovascular water exchange (Kw) measured by non-invasive diffusion-prepared arterial spin label MRI (n = 27 healthy controls [HC], n = 32 SSD) is impaired in SSD and associated with clinical symptoms. Peripheral vascular endothelial health was examined by brachial artery flow-mediated dilation (n = 44 HC, n = 37 SSD) to examine whether centrally measured Kw is related to endothelial functions. Whole-brain average Kw was significantly reduced in SSD (P = .007). Exploratory analyses demonstrated neurovascular water exchange reductions in the right parietal lobe, including the supramarginal gyrus (P = .002) and postcentral gyrus (P = .008). Reduced right superior corona radiata (P = .001) and right angular gyrus Kw (P = .006) was associated with negative symptoms. Peripheral endothelial function was also significantly reduced in SSD (P = .0001). Kw in 94% of brain regions in HC positively associated with peripheral endothelial function, which was not observed in SSD, where the correlation was inversed in 52% of brain regions. This study provides initial evidence of neurovascular water exchange abnormalities, which appeared clinically associated, especially with negative symptoms, in schizophrenia.

Particulate Matter 2.5 Level Modulates Brachial Artery Flow-Mediated Dilation Response to Aerobic Exercise in Healthy Young Men

Particulate matter 2.5 (PM2.5) is an environmental pollutant linked with the risk of cardiovascular disease. Aerobic exercise performed in polluted environments may have fewer benefits because of increased PM2.5 inhalation during exercise. However, the vascular responses to aerobic exercise in high PM2.5 (HPM2.5) conditions remain unknown. This study aimed to examine the acute flow-mediated dilation (FMD) response to moderate-intensity treadmill running in HPM2.5 levels compared to low PM2.5 (LPM2.5) levels in healthy young males. Treadmill running in both HPM2.5 and LPM2.5 levels was completed by nine subjects. Brachial artery FMD was measured before and after the exercise to assess vascular endothelial function. Indoor PM2.5 concentration was significantly higher in HPM2.5 than in LPM2.5 conditions (p &lt; 0.001). Scaled FMD significantly increased after the exercise in LPM2.5 conditions but not in HPM2.5 (p = 0.03), and baseline diameter increased only in HPM2.5 conditions after the exercise (p = 0.001). Baseline diameter and peak diameter were smaller, and time to peak dilation was delayed in HPM2.5 compared to LPM2.5 in pre-exercise intervention measurements (p &lt; 0.05). Therefore, acute PM2.5 exposure can counteract the positive effect of aerobic exercise on vascular endothelial function in young males.

Cardiometabolic function in retired night shift workers and retired day workers

Night shift work is associated with poor cardiometabolic outcomes, even post-retirement. However, the characteristics of cardiometabolic function in retired night shift workers (RNSW) compared to retired day workers (RDW) are not well-understood. Rigorous characterization of cardiometabolic dysfunction in RNSW and RDW will inform targeted risk stratification for RNSW. This observational study evaluated whether RNSW (n = 71) had poorer cardiometabolic function than RDW (n = 83). We conducted a multimodal assessment of cardiometabolic function including metabolic syndrome prevalence, brachial artery flow-mediated dilation, and carotid intima-media thickness. Main analyses tested overall group differences. Sex-stratified follow-up analyses tested group differences separately in men and women. RNSW had 2.6-times higher odds of metabolic syndrome prevalence than RDW in unadjusted analyses (95% CI [1.1,6.3]); this association was not significant when adjusting for age, race and education. RNSW and RDW (Mage = 68.4; 55% female) did not differ in percent flow-mediated dilation or carotid intima-media thickness. In sex-stratified analyses, women RNSW had 3.3-times higher odds of having high body mass index than women RDW (95% CI [1.2,10.4]). Men RNSW had 3.9-times higher odds of having high triglycerides than men RDW (95% CI [1.1,14.2]). No other group differences were observed. We found mixed evidence that night shift work exposure was associated with cardiometabolic dysfunction in retirement, possibly in a sex-specific manner.

Brachial artery flow-mediated dilation in patients with systemic sclerosis: an experience from tertiary care center from North India.

Role of flow-mediated dilatation (FMD) testing in the assessment of the macrovascular dysfunction in systemic sclerosis (SS) and correlation of FMD values with disease severity. Twenty-five patients of SS and 25 healthy age-matched controls were recruited. Modified Rodnan skin thickness score (MRSS) was used for skin thickness assessment. FMD values were measured in the brachial artery. FMD values done at baseline before the initiation of treatment were lower in SSc patients (4.044 ± 2.742) compared to the healthy controls (11.076 ± 5.896) (P < 0.05). Comparison of FMD values between patients with limited cutaneous systemic sclerosis (LSSc) and diffuse cutaneous systemic sclerosis (DSSc) showed a trend toward lower in LSSc (3.182 ± 2.482) as compared to DSSc patients (5.111 ± 2.711); however, the difference was not statistically significant. Patients with lung manifestations on high-resolution CT chest showed lower FMD values (2.66 ± 2.23) compared to those without HRCT changes (6.45 ± 2.56) (P < 0.05). We demonstrate that FMD values in SSc patients were lower when compared to healthy controls. Patients with SS having pulmonary manifestations showed a lower value of FMD. Key Points • FMD is a simple non-invasive tool to assess the endothelial function in patients with systemic sclerosis. • Lower values of FMD in systemic sclerosis suggest that the endothelial dysfunction and values can also be correlated with other organ involvement such as lung and skin involvement. So, lower FMD values might be a useful marker for disease severity.

Effects of exercise during water immersion on arterial function in humans.

Flow-mediated dilation (FMD) provides a valid bioassay of vascular function in humans. Although water immersion induces hemodynamic effects that modify brachial artery shear stress, it is unclear whether water-based exercise modifies FMD. We hypothesized that exercise in 32°C water would decrease brachial artery shear and FMD relative to land-based exercise, whereas exercise in 38°C would increase brachial shear and FMD. Ten healthy participants (8 males; 23.9 ± 3.3 yr) completed 30 min of resistance-matched cycle exercise in three separate conditions: on land and in 32°C and 38°C water. Brachial artery shear rate area under the curve (SRAUC) was measured throughout each condition, with FMD measured pre- and postexercise. Brachial SRAUC increased during exercise in all conditions and was highest across the 38°C condition compared with Land and 32°C conditions (38°C: 27,507 ± 8,350 vs. Land: 9,908 ± 4,738 vs. 32°C: 13,840 ± 5,861 1/s, P < 0.001). Retrograde diastolic shear was greater during 32°C than both Land and 38°C conditions (32°C:-3,869 ± 2,198 vs. Land:-1,602 ± 1,334 vs. 32°C:-1,036 ± 1,754, P < 0.01). FMD increased as a result of 38°C (6.2 ± 1.9 vs. 8.5 ± 2.7%, P = 0.03), with no change in the Land exercise (6.3 ± 2.4 vs. 7.7 ± 2.4%, P = 0.10) or 32°C condition (6.4 ± 3.2 vs. 6.7 ± 3.2%, P = 0.99). Our findings indicate that cycle exercise in hot water attenuates retrograde shear, increases antegrade shear, and FMD. Exercise in 32°C water induces central hemodynamic changes relative to land-based exercise, but these do not translate to increases in FMD in either condition, likely due to the impact of increased retrograde shear. Our findings indicate that modification of shear has direct acute impacts on endothelial function in humans.

Impact of Oxygen Supplementation on Brachial Artery Hemodynamics and Vascular Function During Ascent to 5,050 m

Vizcardo-Galindo, Gustavo A., Connor A. Howe, Ryan L. Hoiland, Howard H. Carter, Christopher K. Willie, Philip N. Ainslie, and Joshua C. Tremblay. Impact of oxygen supplementation on brachial artery hemodynamics and vascular function during ascent to 5,050 m. High Alt Med Biol. 24:27-36, 2023.-High-altitude trekking alters upper limb hemodynamics and reduces brachial artery vascular function in lowlanders. Whether these changes are reversible with the removal of hypoxia is unknown. We investigated the impact of 20 minutes of oxygen supplementation (O2) on brachial artery hemodynamics, reactive hyperemia (RH; microvascular function), and flow-mediated dilation (FMD; endothelial function). Participants (aged 21-42 years) were examined before and with O2 at 3,440 m (n = 7), 4,371 m (n = 7), and 5,050 m (n = 12) using Duplex ultrasound (days 4, 7, and 10 respectively). At 3,440 m, O2 decreased brachial artery diameter (-5% ± 5%; p = 0.04), baseline blood flow (-44% ± 15%; p < 0.001), oxygen delivery (-39 ± 16; p < 0.001), and peak RH (-8% ± 8%; p = 0.02), but not RH normalized for baseline blood flow. Elevated FMD (p = 0.04) with O2 at 3,440 m was attributed to the reduction in baseline diameter. At 5,050 m, a reduction in brachial artery blood flow (-17% ± 22%; p = 0.03), but not oxygen delivery, diameter, RH, or FMD occurred with O2. These findings suggest that during early trekking at high altitude, O2 causes vasoconstriction in the upper limb along the arterial tree (conduit and resistance arteries). With incremental high-altitude exposure, O2 reduces blood flow without compromising oxygen delivery, RH, or FMD, suggesting a differential impact on vascular function modulated by the duration and severity of high-altitude exposure.

Role of Altered Metabolism of Triglyceride-Rich Lipoprotein Particles in the Development of Vascular Dysfunction in Systemic Lupus Erythematosus

Impaired lipid metabolism contributes to accelerated inflammatory responses in addition to promoting the formation of atherosclerosis in systemic lupus erythematosus (SLE). We aimed to evaluate the lipid profile, inflammatory markers, and vascular diagnostic tests in active SLE patients to clarify the association between dyslipidemia and early vascular damage. 51 clinically active SLE patients and 41 age- and gender-matched control subjects were enrolled in the study. Lipoprotein subfractions were detected by Lipoprint. Brachial artery flow-mediated dilation and common carotid intima-media thickness were detected by ultrasonography. Arterial stiffness indicated by augmentation index (Aix) and pulse wave velocity was measured by arteriography. We found significantly higher Aix, higher VLDL ratio, plasma triglyceride, ApoB100, and small HDL, as well as lower HDL-C, large HDL, and ApoA1 in patients with SLE. There was a significant positive correlation of Aix with triglyceride, VLDL, IDL-C, IDL-B, and LDL1. A backward stepwise multiple regression analysis showed IDL-C subfraction to be the best predictor of Aix. Our results indicate that in young patients with SLE, triglyceride-rich lipoproteins influence vascular function detected by Aix. These parameters may be assessed and integrated into the management plan for screening cardiovascular risk in patients with SLE.

Elevated Fibroblast Growth Factor 23 Impairs Endothelial Function through the NF-κB Signaling Pathway.

Roles of fibroblast growth factor 23 (FGF23) in endothelial dysfunction remain controversial, and evidence from population-based studies is lacking. The present study aimed to explore the effects of FGF23 on endothelial dysfunction on the basis of both clinical data of patients with coronary artery disease (CAD) and the in vitro research in human umbilical vein endothelial cells (HUVECs). A total of 321 CAD patients were enrolled after coronary angiography, brachial artery flow-mediated dilation (FMD) was assessed using ultrasound equipment. Serum FGF23, nitric oxide (NO), and endothelin-1 (ET-1) were detected via enzyme-linked immunosorbent assay. Apoptosis was determined using the annexin V-fluorescein isothiocyanate/propidium lodide apoptosis detection kit. Cell migration was evaluated by wound healing and transwell migration assays. Reactive oxide species levels were determined using fluorescent probes, and NF-κB p65 nuclear translocation was assessed via immunofluorescence. Serum FGF23 was significantly increased in CAD patients combined with severe endothelial dysfunction (FMD ＜2%) compared to those with FMD ≥ 2% (P＜0.001). Furthermore, the levels of FGF23 were negatively correlated with NO, whereas positively correlated with ET-1 both in unadjusted analysis and multivariate-adjusted analysis. In HUVECs, FGF23 interfered with the bioavailability of NO via increased oxidative stress. Moreover, FGF23 directly impaired the endothelium by promoting HUVECs apoptosis and attenuating the migration of HUVECs. Additional experiments showed that FGF23 induced endothelial injury through activation of the NF-κB signaling pathway. Elevated FGF23 is clinically associated with endothelial dysfunction in CAD patients, and FGF23 impairs endothelial function through activation of the NF-κB signaling pathway.

Comparison of peripheral and cerebral vascular function between premenopausal, early and late postmenopausal females.

What is the central question of this study? We sought to investigate whether peripheral and cerebrovascular function are impaired in early and late postmenopausal females compared with premenopausal females, while also accounting for nitric oxide and estradiol levels. What is the main finding and its importance? We observed no differences in peripheral vascular and cerebrovascular function between healthy and physically active premenopausal females and early and late postmenopausal females. Our findings contradict previous cross-sectional observations of vascular and cerebrovascular dysfunction across menopause. Longitudinal studies assessing vascular and cerebrovascular outcomes across the menopausal transition are warranted. The risk of cardiovascular and cerebrovascular disease increases in ageing females, coinciding with the onset of menopause. Differences in peripheral and cerebrovascular function across menopausal stages, however, are poorly characterized. The aim of this study was to compare peripheral and cerebrovascular function between healthy premenopausal (PRE), early (1-6 years after final menstrual period; E-POST) and late (>6 years after final menstrual period; L-POST) postmenopausal females. We also explored the association between reproductive hormones, NO bioavailability and cerebrovascular function. In 39 females (40-65 years of age), we measured arterial stiffness, brachial artery flow-mediated dilatation, and cerebrovascular reactivity (CVR) to hypercapnia in the middle (MCAv) and internal (ICA) carotid arteries. Follicle-stimulating hormone, estradiol, progesterone and plasma nitrate and nitrite concentrations were also measured. Years since final menstrual period (PRE, 0±0 years; E-POST, 3±1 years; L-POST, 11±4 years; P<0.001) and estradiol levels (PRE, 145.5±65.6 pgml-1 ; E-POSTm 30.2±81.2 pgml-1 ; L-POST, 7.7±11.3 pgml-1 ; P<0.001) were different between groups. All groups exceeded the guidelines for recommended physical activity. There were no group differences in blood pressure (P=0.382), arterial stiffness (P=0.129), flow-mediated dilatation (P=0.696) or MCAv CVR (P=0.442). The ICA CVR blood flow response was lower in PRE compared with L-POST (26.5±19.2vs. 47.8±12.6%; P=0.010), but after adjusting for age these differences were no longer present. Flow-mediated dilatation (r=0.313, P=0.105) and ICA CVR (r=-0.154, P=0.495) were not associated with the estradiol concentration. There were no associations between the estradiol concentration and NO bioavailability. These results suggest that in healthy, physically active early and late postmenopausal females, vascular and cerebrovascular function is generally well preserved.

PS-C05-10: INDIVIDUALS WITH PRE-IMPAIRED GLUCOSE TOLERANCE (PRE-IGT) HAVE ALREADY ENDOTHELIAL DYSFUNCTION BUT WITH NO SIGNIFICANT IDENTIFIABLE CARDIOVASCULAR RISK FACTORS

Objective: Pre-impaired glucose tolerance (pre-IGT), characterized as normoglycemia with hyperinsulinemia, is the earliest stage of dysmetabolism in type 2 diabetes mellitus (DM). C-peptide, which is equimolar to insulin, has been shown to cause intima-media thickening when present in increased amounts. This study aims to determine the prevalence of endothelial dysfunction among individuals with pre-IGT and to determine the cardiovascular risk factors for developing endothelial dysfunction. Design and method: We employed a cross-sectional analytical study of adult patients with risk factors for developing diabetes [first-degree relative with type 2 DM, obesity, history of gestational diabetes (GDM), and polycystic ovary syndrome (PCOS)]. Brachial artery flow-mediated dilatation (FMD) was performed on pre-IGT patients to test for the presence of endothelial dysfunction. Cardiovascular risk factors evaluated were age, 2-hr insulin and glucose level after 75 gms OGTT, BMI, lipids, and systolic and diastolic blood pressure. Binary logistic regression was used to determine the significant risk factors affecting endothelial dysfunction, Results: Of the 67 subjects, 41 had pre-IGT with a prevalence of 61%. Among the pre-IGT who had FMD studies (31/41), seven had FMD (+) with a prevalence of 22.58%. Although statistically not significant, FMD (+) vs. FMD (-) subjects were respectively, older (mean 28.86 (SD 4.34) vs. 25.96 years (SD 25.96), p = 0.112), more obese (mean (SD) 26.87 (4.36) vs. 25.18 kg/m2 (4.83), p = 0.257), had higher 2nd hr glucose and HbA1c (mean (SD) 2-hr glucose; 106.34 (13.36) vs. 105 mg/dL (17.55), p = 0.620, mean (SD) HbA1c; 5.30 (0.37) vs. 5.23% (0.37), p = 0.669), and higher total cholesterol and LDL (mean (SD) cholesterol; 182.13 (21.51) vs.177.07 mg/dL (20.70), p = 0.620, mean (SD) LDL; 105.68 (3.77) vs. 98.58 mg/dL (19.25), p = 0.357). Conversely, FMD (+) vs. FMD (-) subjects had respectively, lower values of the following; 2nd hour insulin levels (mean (SD) 101.32 (76.10) vs. 122.44 uIU/mL (101.83), p = 0.450), mean (SD) systolic BP (109.71 (11.40) vs.110.67 mmHg (13.10), p = 0.886), and mean (SD) diastolic BP (71 (9.11) vs. 74.13 mmHg (10.60), p = 0.683). Similarly, the difference was not statistically significant. Comparative analyses also yielded no significant difference in the demographics (family history, GDM, PCOS) of the two groups. Conclusion: Endothelial dysfunction is already present among individuals with pre-IGT. The study did not demonstrate any significant difference in the previously reported cardiovascular risk factors contributing to endothelial function abnormality.

Endothelial function assessment by flow-mediated dilation of the brachial artery in acute kidney injury and chronic kidney disease.

Endothelial dysfunction has a significant role in the pathogenesis of cardiovascular events in patients with kidney dysfunction. The present study aimed to compare the level of endothelial dysfunction in patients with chronic kidney disease (CKD) and acute kidney injury (AKI) by brachial artery flow-mediated dilation (FMD) technique. Also, we sought to find whether this non-invasive technique may assist in accurately distinguishing the acute or chronic nature of kidney failure in patients presenting with uremia for the first time. Demographic and medical characteristics, and laboratory and renal ultrasonography data of the patients with AKI and CKD were collected and compared with a control group. Brachial artery FMD was measured using a Toshiba aplio 300 device with a 7.5 MHz linear probe. In a total of 175 patients with a mean (SD) age of 55.96(15.54) years, FMD% was significantly lower in the CKD and AKI patients compared to the control group (Mean±SD: 16.28%±10.52%), 16.28 %±4.35%, and 24.24±5.71, respectively, p<0.001). Among the different causes of AKI, contrast-induced nephropathy (10.78%±1.75%), volume depletion (14.87%±1.22%), and post-renal AKI (15.96%±1.54%) had the lowest levels of FMD. Also, a significant correlation between FMD and eGFR (r=0.26, P<0.001), serum Hb (r=0.18, P=0.013), Na (r=0.19, P=0.011), BUN (r=-0.21, P=0.005) and Cr (r=- 0.13, P=0.084) was reported. Compared to the control group, CKD and AKI patients showed greater levels of endothelial dysfunction as evidenced by lower brachial artery FMD. However, the FMD technique did not appear to be a practical method in differentiating CKD and AKI in patients presenting with uremia for the first time.

Impact of handgrip exercise and ischemic preconditioning on local and remote protection against endothelial reperfusion injury in young men.

Ischemic preconditioning (IPC), cyclical bouts of nonlethal ischemia, provides immediate protection against ischemic injury, which is evident both locally and remotely. Given the similarities in protective effects of exercise with ischemic preconditioning, we examined whether handgrip exercise also offers protection against endothelial ischemia-reperfusion (IR) injury and whether this protection is equally present in the local (exercised) and remote (contralateral, nonexercised) arm. Fifteen healthy males (age, 24 ± 3 yr; body mass index, 25 ± 2 kg/m2) attended the laboratory on three occasions. Bilateral brachial artery flow-mediated dilation (FMD) was examined at rest and after a temporary IR injury in the upper arm. Before the IR injury, in the dominant (local) arm, participants performed (randomized, counterbalanced): 1) 4 × 5 min unilateral handgrip exercise (50% maximal voluntary contraction), 2) 4 × 5 min unilateral IPC (220 mmHg), or 3) 4 × 5 min rest (control). Data were analyzed using repeated-measures general linear models. Allometrically scaled FMD declined after IR in the control condition (4.6 ± 1.3% to 2.2 ± 1.7%, P < 0.001), as well as following handgrip exercise (4.6 ± 1.6% to 3.4 ± 1.9%, P = 0.01), however, was significantly attenuated with IPC (4.5 ± 1.4% to 3.8 ± 3.5%, P = 0.14). There were no differences between the local and remote arm. Our findings reinforce the established protective effects of IPC in young, healthy males and also highlight a novel strategy to protect against IR injury with handgrip exercise, which warrants further study.

High sodium intake differentially impacts brachial artery dilation when evaluated with reactive versus active hyperemia in salt resistant individuals.

This study sought to determine if high sodium (HS) intake in salt resistant (SR) individuals attenuates upper limb arterial dilation in response to reactive (occlusion) and active (exercise) hyperemia, two stimuli with varying vasodilatory mechanisms, and the role of oxidative stress in this response. Ten young, SR participants (9 males, 1 female) consumed a 7-day HS (6,900 mg/day) and a 7-day recommended sodium intake (RI: 2,300 mg/day) diet in a randomized order. On the last day of each diet, brachial artery (BA) function was evaluated via reactive (RH-FMD: 5 min of cuff occlusion) and active [handgrip (HG) exercise] hyperemia after consumption of both placebo (PL) and antioxidants (AO). The HS diet significantly elevated sodium excretion (P < 0.05), but mean arterial blood pressure was unchanged. During the PL condition, the HS diet significantly reduced RH-FMD when compared with RI diet (P = 0.01), but this reduction was significantly restored (P = 0.01) when supplemented with AO (HS + PL: 5.9 ± 3.4; HS + AO: 8.2 ± 2.7; RI + PL: 8.9 ± 4.7; RI + AO: 7.0 ± 2.1%). BA shear-to-dilation slopes, evaluated across all HG exercise workloads, were not significantly different across sodium intervention or AO supplementation. In SR individuals, HS intake impaired BA function when assessed via RH-FMD, but was restored with acute AO consumption suggesting oxidative stress as a contributor to this dysfunction. However, exercise-induced BA dilation was unaltered, potentially implicating an inability of HS intake to influence the mechanisms responsible for effectively maintaining skeletal muscle perfusion during exercise.NEW & NOTEWORTHY This study examined if high sodium (HS) intake in salt resistant (SR) individuals attenuates brachial artery (BA) flow-mediated dilation in response to reactive (occlusion) and active (exercise) hyperemia. In SR individuals, HS intake impaired reactive hyperemia-induced BA dilation, but not exercise-induced BA dilation. This finding suggests that although brachial artery nitric oxide bioavailability may be reduced following HS intake, the redundant mechanisms associated with adequate upper limb blood flow regulation during exercise are maintained.

The acute effect of heat exposure on forearm macro- and microvascular function: Impact of measurement timing, heating modality and biological sex.

What is the central question of this study? Do measurement timing, heating modality and biological sex modulate the acute effect of heat exposure on brachial artery flow-mediated dilatation and postocclusion reactive hyperaemia? What is the main finding and its importance? The acute effect of heat exposure on brachial artery flow-mediated dilatation and postocclusion reactive hyperaemia is: (1) transient and short lasting; (2) different between forearm and whole-body heating; (3) unaffected by forearm heating during whole-body heating; and (4) not different but not always equivalent between males and females. These findings provide a useful basis for future studies to investigate the acute effect of heat exposure on vascular function. The aim of this study was to gain a better understanding of the acute effect of heat exposure on brachial artery flow-mediated dilatation (FMD) and postocclusion reactive hyperaemia (PORH) by: characterizing the time course of changes post-heating; comparing forearm and whole-body heating; determining the impact of forearm heating during whole-body heating; and comparing males and females. Twenty adults (11 males and nine females; 28±6years of age) underwent two forearm [10min electric blanket (EB) or 30min hot water immersion (WI)] and two whole-body [60min water-perfused suit with forearm covered (WBH-C) or uncovered (WBH-U)] heating modalities. The FMD and PORH were measured before and after (≤5, 30, 60, 90 and 120min) heating. The FMD increased from baseline 30min after EB, and 30 and 90min after WI. In contrast, FMD decreased from baseline immediately after both WBH modalities. Peak PORH increased immediately after WI and both WBH modalities. Total PORH did not differ after WI, whereas it decreased immediately after both WBH modalities. Covering the forearm during WBH did not alter acute changes in FMD or PORH. Changes in FMD and PORH did not differ statistically between males and females during each heating modality, although the observed differences could not always be considered equivalent. These results demonstrate that the acute effect of heat exposure on brachial artery FMD and PORH is: (1) transient and short lasting; (2) different between forearm heating and WBH; (3) unaffected by direct forearm heating during WBH; and (4) not different but not always equivalent between males and females.

Clinical value of flow-mediated dilatation of brachial artery in hypertensive disorders complicating pregnancy.

Hypertensive disorders complicating pregnancy (HDCP) are common pregnancy-related disorders. In this study, we aimed to study the clinical value of flow-mediated dilation (FMD) in HDCP and its association with endothelial dysfunction and HDCP-related factors. 160 HDCP patients and 120 healthy pregnancies were enrolled in the study. The expressions of endothelial function markers and FMD were determined. In addition, their correlations in HDCP patients were also analyzed using Pearson's correlation analysis. FMD value decreased gradually from normal pregnancy to severe PE. The levels of plasma nitric oxidase (NO) were significantly lower in the HDCP group than those in the control group, while the levels of plasma endothelin-1 (ET-1) were increased dramatically in the HDCP group. Moreover, the levels of placental growth factor (PLGF) in HDCP women were significantly lower, while the soluble FMS-like tyrosine kinase 1 (sFLt-1) levels were markedly higher than those in control. In addition, the FMD value was correlated with the levels of plasma NO, ET-1, PLGF and sFlt1. It was also found that lower levels of FMD correspond to endothelial dysfunction and abnormal concentrations of PLGF and sFlt-1. The FMD value was associated with endothelial function indicators and could be a strong and non-invasive measure to predict HDCP. The association between the FMD values and endothelial function indicators in HDCP could be helpful for the prediction of pregnant hypertension more accurately.

Tracking peripheral vascular function for six months in young adults following SARS-CoV-2 infection.

SARS-CoV-2 infection is known to instigate a range of physiologic perturbations, including vascular dysfunction. However, little work has concluded how long these effects may last, especially among young adults with mild symptoms. To determine potential recovery from acute vascular dysfunction in young adults (8M/8F, 21 ± 1yr, 23.5± 3.1kg⋅m-2 ), we longitudinally tracked brachial artery flow-mediated dilation (FMD) and reactive hyperemia (RH) in the arm and hyperemic response to passive limb movement (PLM) in the leg, with Doppler ultrasound, as well as circulating biomarkers of inflammation (interleukin-6, C-reactive protein), oxidative stress (thiobarbituric acid reactive substances, protein carbonyl), antioxidant capacity (superoxide dismutase), and nitric oxide bioavailability (nitrite) monthly for a 6-month period post-SARS-CoV-2 infection. FMD, as a marker of macrovascular function, improved from month 1 (3.06 ± 1.39%) to month 6 (6.60 ± 2.07%; p< 0.001). FMD/Shear improved from month one (0.10± 0.06 AU) to month six (0.18 ± 0.70 AU; p=0.002). RH in the arm and PLM in the leg, as markers of microvascular function, did not change during the 6 months (p> 0.05). Circulating markers of inflammation, oxidative stress, antioxidant capacity, and nitric oxide bioavailability did not change during the 6 months (p> 0.05). Together, these results suggest some improvements in macrovascular, but not microvascular function, over 6 months following SARS-CoV-2 infection. The data also suggest persistent ramifications for cardiovascular health among those recovering from mild illness and among young, otherwise healthy adults with SARS-CoV-2.

Sympathetic Neural Overdrive, Aortic Stiffening, Endothelial Dysfunction, and Impaired Exercise Capacity in Severe COVID-19 Survivors: A Mid-Term Study of Cardiovascular Sequelae.

COVID-19 has become a dramatic health problem during this century. In addition to high mortality rate, COVID-19 survivors are at increased risk for cardiovascular diseases 1-year after infection. Explanations for these manifestations are still unclear but can involve a constellation of biological alterations. We hypothesized that COVID-19 survivors compared with controls exhibit sympathetic overdrive, vascular dysfunction, cardiac morpho-functional changes, impaired exercise capacity, and increased oxidative stress. Nineteen severe COVID-19 survivors and 19 well-matched controls completed the study. Muscle sympathetic nerve activity (microneurography), brachial artery flow-mediated dilation and blood flow (Doppler-Ultrasound), carotid-femoral pulse wave velocity (Complior), cardiac morpho-functional parameters (echocardiography), peak oxygen uptake (cardiopulmonary exercise testing), and oxidative stress were measured ~3 months after hospital discharge. Complementary experiments were conducted on human umbilical vein endothelial cells cultured with plasma samples from subjects. Muscle sympathetic nerve activity and carotid-femoral pulse wave velocity were greater and brachial artery flow-mediated dilation, brachial artery blood flow, E/e' ratio, and peak oxygen uptake were lower in COVID-19 survivors than in controls. COVID-19 survivors had lower circulating antioxidant markers compared with controls, but there were no differences in plasma-treated human umbilical vein endothelial cells nitric oxide production and reactive oxygen species bioactivity. Diminished peak oxygen uptake was associated with sympathetic overdrive, vascular dysfunction, and reduced diastolic function in COVID-19 survivors. Our study revealed that COVID-19 survivors have sympathetic overactivation, vascular dysfunction, cardiac morpho-functional changes, and reduced exercise capacity. These findings indicate the need for further investigation to determine whether these manifestations are persistent longer-term and their impact on the cardiovascular health of COVID-19 survivors.