Assessment of endothelial function using digital pulse amplitude tonometry

Endothelial dysfunction in chronic kidney disease: Mechanisms, biomarkers, diagnostics, and therapeutic strategies

Endothelial cells regulate vascular tone, blood flow, coagulation, and inflammation, with heterogeneous populations serving specific roles throughout the body. In the kidney, endothelial cells maintain vascular integrity and function, contribute to filtration, and support other renal structures. Nitric oxide (NO) is a key signaling molecule that maintains vascular tone and endothelial function. It is synthesized by nitric oxide synthase (NOS) isoforms, with endothelial NOS playing a central role in vascular health. Chronic kidney disease (CKD) is characterized by reduced NO bioavailability, driven by the accumulation of endogenous NOS inhibitors such as asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA). Uremic toxins, oxidative stress, and proinflammatory cytokines contribute to a prothrombotic and proinflammatory state, contributing to endothelial dysfunction and exacerbating cardiovascular (CV) risks in CKD. Biomarkers such as ADMA, SDMA, endothelial microparticles, and soluble adhesion molecules offer insights into vascular health, while invasive or noninvasive diagnostic techniques can assess endothelial function in CKD. Effective management strategies focus on enhancing NO bioavailability, controlling oxidative stress, reducing inflammation, and optimizing dialysis to minimize uremic toxin levels. Emerging therapeutic approaches, including antioxidant therapies and endothelial progenitor cell-based interventions, show promise in preserving vascular function. A multifaceted approach to managing endothelial dysfunction is critical for mitigating CV complications and improving patient outcomes in CKD.

Benefits of Dietary Supplementation with Specific Silicon-Enriched Spirulina on Arterial Function in Healthy Elderly Individuals: A Randomized, Placebo-Controlled Trial

Background/Objectives: Vascular aging is associated with increased arterial stiffness and changes in the wall structure, leading to a loss of elasticity. Silicon is abundant in arteries and plays a key role in the synthesis and stabilization of elastin fibers. In animal models of accelerated cardiovascular aging, a specific nutritional supplement based on silicon-enriched spirulina (SpSi) has been shown to have beneficial effects on vascular function. The present study, designed as a randomized, double-blind, placebo-controlled trial, aimed to evaluate the effectiveness of this SpSi supplement on aging-related changes in vascular function among healthy older adults. Methods: Here, 120 healthy volunteers aged 60-75 years were enrolled and randomly assigned to either the SpSi group (n = 60) or placebo group (n = 60). Over 6 months, the participants received either 3.5 g of specific 1% silicon-enriched spirulina (SpSi group) or placebo tablets daily. The primary outcome was the assessment of arterial wall pressure waveforms, which included blood pressure (BP) readings and the determination of the aortic pulse wave velocity (aPWV). Secondary outcomes included the vasomotor endothelial function through post-ischemic vasorelaxation, measured using the reactive hyperemia index (RHI), and carotid intima-media thickness. Results: When considering the entire sample, none of the studied parameters differed between the placebo and SpSi groups. However, when focusing on individuals with high-normal blood pressure (i.e., systolic BP between 130 and 150 mmHg) and aPWV levels above cutoff values (>10 m/s), the BP decreased by 8% (p < 0.001) and aPWV decreased by 13.5% (p < 0.0001) in subjects receiving SpSi. In individuals with BP and aPWV levels below the cutoff values, no effect was observed. Conclusions: In healthy elderly individuals, SpSi supplementation improved high-normal blood pressure and aortic pulse wave velocity, suggesting an enhanced vascular function.

The impact of prediabetes and diabetes on endothelial function in a large population-based cohort

BACKGROUND

Diabetes and prediabetes are well-recognized risk factors for cardiovascular disease (CVD) and are marked by vascular endothelial dysfunction (ED). However, there is a scarcity of thorough population-based studies examining ED in individuals with diabetes/prediabetes free from manifest CVD. Here, we examined the association between ED assessed by reactive hyperaemia index (RHI) in the finger and diabetes/prediabetes in a large middle-aged population cohort.

METHODS

Within the Malmö Offspring Study, following the exclusion of participants <30 years and participants with prevalent CVD, 1384 participants had complete data on all covariates. The RHI was calculated using pulse amplitude tonometry. ED was defined as RHI < 1.67. Multivariable logistic and linear regression models were conducted to investigate associations between ED and RHI with diabetes and prediabetes.

RESULTS

The study population had a mean age of 53.6 ± 7.6 years (53% women). In study participants with manifest diabetes (n = 121) and prediabetes (n = 514), ED was present in 42% and 25% respectively, compared to 23% in those with normal glucometabolic status. In multivariable logistic regression analyses, prevalent diabetes was significantly associated with ED (OR 1.95; 95%CI 1.57-3.39; p = 0.002), as well as with lower RHI (β-coeff. -0.087; p = 0.002). However, prediabetes showed no association with neither ED nor RHI.

CONCLUSION

In a population free from CVD, vascular endothelial dysfunction was primarily associated with manifest diabetes, but not with prediabetes, implying that finger ED may develop when diabetes is established, rather than being an early sign of glucose intolerance. Further research is needed to explore whether addressing glucose intolerance could potentially delay or prevent vascular ED onset.

Clinical Implications of COVID-19-Related Endothelial Dysfunction

Endothelial dysfunction represents a measurable and early manifestation of vascular disease. Emerging evidence suggests cardiovascular risk remains elevated after COVID-19 infection for at least 12 months, regardless of cardiovascular disease status prior to infection. We review the relationship between the severity of endothelial dysfunction and the severity of acute COVID-19 illness, the degree of impairment following recovery in both those with and without postacute sequalae SARS-CoV-2 infection, and current therapeutic efforts targeting endothelial function in patients following COVID-19 infection. We identify gaps in the literature to highlight specific areas where clinical research efforts hold promise for progress in understanding the connections between endothelial function, COVID-19, and clinical outcomes that will lead to beneficial therapeutics.

Pilot Assessment of Piezoelectric Transducers as a Cost-Effective Alternative to EndoPAT

INTRODUCTION

Current microvascular assessments may not be practical or accessible requiring experienced personnel and/or ongoing equipment costs. Piezoelectric transducers can reliably obtain finger blood pressure waves, similar to peripheral arterial tonometry devices; thus, they could be used to estimate microvascular function. We aimed to validate piezoelectric transducers as an alternative measure of microvascular function compared to EndoPAT.

METHODS

Twenty-five adults (aged 20-64 years) completed reactive hyperemia (5 min forearm circulatory occlusion and 3 min recovery) with piezoelectric transducers on the middle fingers and EndoPAT probes on the index fingers. Average area under the curve (AUC) of the pulse wave signal for the occluded and control arms was determined at baseline, every 30 s post-occlusion, and 10 s around the peak response. Microvascular function index (MFI) was calculated as the ratio of AUC post-occlusion to AUC baseline in the test arm, then normalized to the same ratio in the control arm. MFI at each time point was correlated with the reactive hyperemia index (RHI) from the EndoPAT.

RESULTS

The greatest significance was found between RHI and MFI at 10 s around the peak response (Spearman's r = 0.67, p = 0.0002; Pearson's r = 0.76, p = 0.00001).

CONCLUSION

MFI is a reusable and user-friendly microvascular function assessment that could provide better access to vascular health screening.

Endothelial Dysfunction and Pre-Existing Cognitive Disorders in Stroke Patients

BACKGROUND

The origin of pre-existing cognitive impairment in stroke patients remains controversial, with a vascular or a degenerative hypothesis.

OBJECTIVE

To determine whether endothelial dysfunction is associated with pre-existing cognitive problems, lesion load and biological anomalies in stroke patients.

METHODS

Patients originated from the prospective STROKDEM study. The baseline cognitive state, assessed using the IQ-CODE, and risk factors for stroke were recorded at inclusion. Patients with an IQ-CODE score >64 were excluded. Endothelial function was determined 72 h after stroke symptom onset by non-invasive digital measurement of endothelium-dependent flow-mediated dilation and calculation of the reactive hyperemia index (RHI). RHI ≤ 1.67 indicated endothelial dysfunction. Different biomarkers of endothelial dysfunction were analysed in blood or plasma. All patients underwent MRI 72 h after stroke symptom onset.

RESULTS

A total of 86 patients were included (52 males; mean age 63.5 ± 11.5 years). Patients with abnormal RHI have hypertension or antihypertensive treatment more often. The baseline IQ-CODE was abnormal in 33 (38.4%) patients, indicating a pre-existing cognitive problem. Baseline IQ-CODE > 48 was observed in 15 patients (28.3%) with normal RHI and in 18 patients (54.6%) with abnormal RHI (p = 0.016). The RHI median was significantly lower in patients with abnormal IQ-CODE. Abnormal RHI was associated with a significantly higher median FAZEKAS score (2.5 vs. 2; p = 0.008), a significantly higher frequency of periventricular lesions (p = 0.015), more white matter lesions (p = 0.007) and a significantly higher cerebral atrophy score (p < 0.001) on MRI. Vascular biomarkers significantly associated with abnormal RHI were MCP-1 (p = 0.009), MIP_1a (p = 0.042), and homocysteinemia (p < 0.05).

CONCLUSIONS

A vascular mechanism may be responsible for cognitive problems pre-existing stroke. The measurement of endothelial dysfunction after stroke could become an important element of follow-up, providing an indication of the functional and cognitive prognosis of stroke patients.

Endothelial and inflammatory pathophysiology in dengue shock: New insights from a prospective cohort study in Vietnam

Dengue shock (DS) is the most severe complication of dengue infection; endothelial hyperpermeability leads to profound plasma leakage, hypovolaemia and extravascular fluid accumulation. At present, the only treatment is supportive with intravenous fluid, but targeted endothelial stabilising therapies and host immune modulators are needed. With the aim of prioritising potential therapeutics, we conducted a prospective observational study of adults (≥16 years) with DS in Vietnam from 2019-2022, comparing the pathophysiology underlying circulatory failure with patients with septic shock (SS), and investigating the association of biomarkers with clinical severity (SOFA score, ICU admission, mortality) and pulmonary vascular leak (daily lung ultrasound for interstitial and pleural fluid). Plasma was collected at enrolment, 48 hours later and hospital discharge. We measured biomarkers of inflammation (IL-6, ferritin), endothelial activation (Ang-1, Ang-2, sTie-2, VCAM-1) and endothelial glycocalyx breakdown (hyaluronan, heparan sulfate, endocan, syndecan-1). We enrolled 135 patients with DS (median age 26, median SOFA score 7, 34 required ICU admission, 5 deaths), together with 37 patients with SS and 25 healthy controls. Within the DS group, IL-6 and ferritin were associated with admission SOFA score (IL-6: βeta0.70, p<0.001 & ferritin: βeta0.45, p<0.001), ICU admission (IL-6: OR 2.6, p<0.001 & ferritin: OR 1.55, p<0.001) and mortality (IL-6: OR 4.49, p = 0.005 & ferritin: OR 13.8, p = 0.02); both biomarkers discriminated survivors and non-survivors at 48 hours and all patients who died from DS had pre-mortem ferritin ≥100,000ng/ml. IL-6 most strongly correlated with severity of pulmonary vascular leakage (R = 0.41, p<0.001). Ang-2 correlated with pulmonary vascular leak (R = 0.33, p<0.001) and associated with SOFA score (β 0.81, p<0.001) and mortality (OR 8.06, p = 0.002). Ang-1 was associated with ICU admission (OR 1.6, p = 0.005) and mortality (OR 3.62, p = 0.006). All 4 glycocalyx biomarkers were positively associated with SOFA score, but only syndecan-1 was associated with ICU admission (OR 2.02, p<0.001) and mortality (OR 6.51, p<0.001). This study highlights the central role of hyperinflammation in determining outcomes from DS; the data suggest that anti-IL-1 and anti-IL-6 immune modulators and Tie2 agonists may be considered as candidates for therapeutic trials in severe dengue.

Correlation between the Capillary Blood Flow Characteristics and Endothelium Function in Healthy Volunteers and Patients Suffering from Coronary Heart Disease and Atrial Fibrillation: A Pilot Study

Coronary heart disease (CHD) and atrial fibrillation (AF) pose significant health risks and require accurate diagnostic tools to assess the severity and progression of the diseases. Traditional diagnostic methods have limitations in providing detailed information about blood flow characteristics, particularly in the microcirculation. This study's objective was to examine and compare the microcirculation in both healthy volunteers and patient groups with CHD and AF. Furthermore, this study aimed to identify a relationship between blood microcirculation parameters and endothelial function. Digital capillaroscopy was employed to assess the microcirculation parameters, for example, such as capillary blood flow velocity, the size of red blood cell aggregates, and the number of aggregates per min and per running mm. The results indicate significant alterations in blood flow characteristics among patients with CHD and AF compared to healthy volunteers. For example, capillary blood flow velocity is statistically significantly decreased in the case of CHD and AF compared to the healthy volunteers (p < 0.001). Additionally, the correlation between the measured parameters is different for the studied groups of patients and healthy volunteers. These findings highlight the potential of digital capillaroscopy as a non-invasive tool for evaluating blood flow abnormalities (red blood cell aggregates and decreased capillary blood flow velocity) in cardiovascular diseases, aiding in early diagnosis and disease management.

Effect of Remote Ischaemic Preconditioning on Perioperative Endothelial Dysfunction in Non-Cardiac Surgery: A Randomised Clinical Trial

Endothelial dysfunction result from inflammation and excessive production of reactive oxygen species as part of the surgical stress response. Remote ischemic preconditioning (RIPC) potentially exerts anti-oxidative and anti-inflammatory properties, which might stabilise the endothelial function after non-cardiac surgery. This was a single centre randomised clinical trial including 60 patients undergoing sub-acute laparoscopic cholecystectomy due to acute cholecystitis. Patients were randomised to RIPC or control. The RIPC procedure consisted of four cycles of five minutes of ischaemia and reperfusion of one upper extremity. Endothelial function was assessed as the reactive hyperaemia index (RHI) and circulating biomarkers of nitric oxide (NO) bioavailability (L-arginine, asymmetric dimethylarginine (ADMA), L-arginine/ADMA ratio, tetra- and dihydrobiopterin (BH4 and BH2), and total plasma biopterin) preoperative, 2–4 h after surgery and 24 h after surgery. RHI did not differ between the groups (p = 0.07). Neither did levels of circulating biomarkers of NO bioavailability change in response to RIPC. L-arginine and L-arginine/ADMA ratio was suppressed preoperatively and increased 24 h after surgery (p < 0.001). The BH4/BH2-ratio had a high preoperative level, decreased 2–4 h after surgery and remained low 24 h after surgery (p = 0.01). RIPC did not influence endothelial function or markers of NO bioavailability until 24 h after sub-acute laparoscopic cholecystectomy. In response to surgery, markers of NO bioavailability increased, and oxidative stress decreased. These findings support that a minimally invasive removal of the inflamed gallbladder countereffects reduced markers of NO bioavailability and increased oxidative stress caused by acute cholecystitis.

Stress and social isolation, and its relationship to cardiovascular risk in young adults with intellectual disability

PURPOSE

Stress produces many physiological changes, some of which may contribute to the development of cardiovascular disease (CVD). Individuals with intellectual disability (ID) are exposed to multiple and stressful challenges everyday which may put them at increased cardiovascular risk. This current study aimed to establish whether adults with ID experience higher levels of subjective stress and encounter different stressors (including social isolation) than the general population, and whether there is a relationship between stress and cardiometabolic profile in this population.

METHODS

Adults with ID (n = 35) aged 18-45 years completed the Subjective Stress Survey, and underwent a physiological assessment to measure blood pressure, metabolic profile and subclinical CVD risk factors, and were compared to a control group (n = 29). Multiple regression was used to investigate whether cardiometabolic parameters were predicative of SSS scores.

RESULTS

Findings showed adults with ID have higher perceived stress levels (total score ID: 21.3 ± 11.4 vs control: 13.9 ± 9.0, p = 0.006), which is elicited by unique stressors, when compared to people without ID. Stress was strongly associated with increased social isolation (r = -0.38, p = 0.002) and with obesity in females with mild ID (r = 0.72). Regression showed that arterial stiffness was predictive of total SSS score (p = 0.038).

CONCLUSIONS

Adults with ID aged 18-45 years report higher levels of perceived stress when compared to people without ID.Implications for RehabilitationReducing stress in this young population may prevent development of arterial stiffness, and consequently lower the risk of cardiometabolic morbidity and mortality.There are unique targets for stress management in young adults with intellectual disability, including supporting decision-making and improving self-efficacy.Improving community integration and reducing social isolation may decrease perceived stress in young adults with intellectual disability.

HIV and race are independently associated with endothelial dysfunction

OBJECTIVE

Evaluating the vascular function in HIV-infected compared with HIV uninfected with assessment of body composition, inflammation, and gut integrity markers.

DESIGN

A noninvasive test that measures the endothelial function.

METHODS

We included participants at least 18 years old, with peripheral arterial tonometry testing (EndoPAT2000) between 2014 and 2022. Persons with HIV (PWH) had documented infection, a stable ART regimen, and a viral load less than 400 copies/ml. We measured the vessel's function with the reactive hyperemia index (RHI) (normal >1.67) and Augmentation Index. Lower Augmentation Index reflect better arterial elasticity. We assessed markers of systemic inflammation, immune activation, and gut integrity. We used linear mixed models to estimate endothelial dysfunction with a significant P value less than 0.05.

RESULTS

Overall, 511 participants (296 HIV-infected; 215 HIV-uninfected controls) were included. Estimated RHI among PWH was 13% lower (P = 0.01) compared with persons without HIV. In nonwhite race, the estimated RHI was 9% lower (P = 0.001) than white race. For every 1% increase in BMI, we would expect RHI to increase 0.17% (P = 0.01). At the time of EndoPAT, the estimated RHI was 8% lower (P = 0.04) among protease inhibitor users compared with PWH who were not taking protease inhibitors. The estimated odds of abnormal RHI ≤1.67) is 1.56 times greater [95% confidence interval (CI) 1.05-2.31] in nonwhite race compared with white race, independent of HIV status [OR = 1.4 (95% CI 0.94-2.13)]. There was not enough evidence to suggest that inflammation, gut, or monocyte markers, current or nadir CD4+ cell count, or duration of HIV were associated with endothelial dysfunction.

CONCLUSION

HIV, nonwhite race, and protease inhibitor use are independently associated with endothelial dysfunction.

Prognostic value of reactive hyperemia index using peripheral artery tonometry in patients with heart failure

Given the high prevalence and poor prognosis of heart failure (HF), finding prognostic factors for patients with HF is crucial. This study investigated the prognostic value of reactive hyperemia index (RHI), a measure of endothelial function, in HF. A total of 90 HF patients (mean age, 63.7 ± 13.2 years; female, 25.6%) with a history of hospitalization for HF treatment were prospectively enrolled. RHI was measured using digital arterial tonometry in a stable condition. Clinical events, including all-cause death and HF admission, were assessed. During the median follow-up of 3.66 years (interquartile range, 0.91-4.94 years), 26 clinical events (28.9%) occurred. Although there were no significant differences in risk factors and laboratory findings according to the occurrence of clinical events, the RHI value was significantly lower in patients with clinical events than in those without (1.21 ± 0.34 vs. 1.68 ± 0.48; P < 0.001). Kaplan-Meier survival analysis showed that a lower RHI value (< 1.48) was associated with a significantly higher incidence rate of clinical events (log-rank P < 0.001). In multivariable cox regression analysis, a low RHI value (< 1.48) was associated with an increased risk of clinical events (hazard ratio, 14.09; 95% confidence interval, 3.61-54.99; P < 0.001) even after controlling for potential confounders. Our study showed that reduced RHI was associated with an increased risk of adverse clinical outcomes in HF. This suggests that endothelial dysfunction may be an important prognostic marker in patients with HF.

Sex-related differences in endothelial function and blood viscosity in the elderly population

Elderly represents a growing population and cardiovascular diseases (CVD) is one of the leading causes of mortality in this population. Sex differences are involved in CVD with middle-aged males being at higher risk than females. After menopause, females are no longer protected by hormones and the role of sex on cardiovascular parameters involved in CVD, such as endothelial function and blood viscosity, is still unclear. The purpose of this study was to investigate the effect of sex on endothelial function, blood viscosity and CVD in elderly. Clinical investigation and blood analyses were performed on 182 (93 females and 89 males) elderly participants (mean age: 75.83 ± 1.22). Health status of participants were classified. Sex differences in endothelial function, blood viscosity, high density lipoprotein (HDL), hematocrit, and red blood cell (RBC) aggregation were assessed. CVD prevalence was higher in males (27.0%) than in females (5.4%) (p < 0.001). Females had higher vasoreactivity (p = 0.014) and HDL (p < 0.001) level than males. Blood viscosity was higher in males than in females at any shear rate (p < 0.001). Hematocrit was greater in males than in females (p < 0.001) while RBC aggregation did not differ between the two populations. To conclude, females have less CVD than age-matched males that might be due to their greater vascular function and lower blood viscosity.

Hyperbaric oxygen for treatment of long COVID-19 syndrome (HOT-LoCO): protocol for a randomised, placebo-controlled, double-blind, phase II clinical trial

INTRODUCTION

Long COVID-19, where symptoms persist 12 weeks after the initial SARS-CoV-2-infection, is a substantial problem for individuals and society in the surge of the pandemic. Common symptoms are fatigue, postexertional malaise and cognitive dysfunction. There is currently no effective treatment and the underlying mechanisms are unknown, although several hypotheses exist, with chronic inflammation as a common denominator. In prospective studies, hyperbaric oxygen therapy (HBOT) has been suggested to be effective for the treatment of similar syndromes such as chronic fatigue syndrome and fibromyalgia. A case series has suggested positive effects of HBOT in long COVID-19. This randomised, placebo-controlled clinical trial will explore HBOT as a potential treatment for long COVID-19. The primary objective is to evaluate if HBOT improves health-related quality of life (HRQoL) for patients with long COVID-19 compared with placebo/sham. The main secondary objective is to evaluate whether HBOT improves endothelial function, objective physical performance and short-term HRQoL.

METHODS AND ANALYSIS

A randomised, placebo-controlled, double-blind, phase II clinical trial in 80 previously healthy subjects debilitated due to long COVID-19, with low HRQoL. Clinical data, HRQoL questionnaires, blood samples, objective tests and activity metre data will be collected at baseline. Subjects will be randomised to a maximum of 10 treatments with hyperbaric oxygen or sham treatment over 6 weeks. Assessments for safety and efficacy will be performed at 6, 13, 26 and 52 weeks, with the primary endpoint (physical domains in RAND 36-Item Health Survey) and main secondary endpoints defined at 13 weeks after baseline. Data will be reviewed by an independent data safety monitoring board.

ETHICS AND DISSEMINATION

The trial is approved by the Swedish National Institutional Review Board (2021-02634) and the Swedish Medical Products Agency (5.1-2020-36673). Positive, negative and inconclusive results will be published in peer-reviewed scientific journals with open access.

TRIAL REGISTRATION NUMBER

NCT04842448.

Differential Sex-Specific Effects of Angiotensin-Converting Enzyme Inhibition and Angiotensin Receptor Blocker Therapy on Arterial Function in Hypertension: CALIBREX Trial

BACKGROUND

Increased arterial stiffness is associated with adverse cardiovascular outcomes. We studied the sex-specific impact of angiotensin antagonists on vascular function in hypertension with the hypothesis that their effects on arterial stiffness may be variable in men and women.

METHODS

In 141 hypertensive participants with mild cognitive impairment (age 65.9±7.7, 57% female), candesartan (up to 32 mg, n=77) or lisinopril (up to 40 mg, n=64) were administered to achieve blood pressure <140/90 mm Hg. Pulse wave velocity, central pulse pressure, and central augmentation index were measured using applanation tonometry (SphygmoCor, Australia). Multivariate linear regression and mixed model analyses were performed using intention-to-treat and per protocol analyses for those completing the study.

RESULTS

Blood pressure reduction was similar among candesartan and lisinopril groups. Compared with candesartan, lisinopril therapy resulted in lower pulse wave velocity (0.5±0.8 versus -0.7±0.4 m/s, respectively; P=0.003) and central pulse pressure (-1±3 versus -7±4 mm Hg; P=0.03) after 1 year. There was a significant interaction by sex whereby the improvements in pulse wave velocity and central pulse pressure with lisinopril compared with candesartan were only observed in women. In contrast, there was greater improvement in augmentation index with candesartan compared with lisinopril (-4±7% versus -1.5±8%; P=0.05), with no sex differences.

CONCLUSIONS

Despite equipotent antihypertensive effects, lisinopril was more effective than candesartan at lowering arterial stiffness in women. In contrast, candesartan was more effective than lisinopril in improving pulse wave reflections in both sexes. These findings demonstrate differential sex-specific effects of renin-angiotensin system antagonists on arterial function in hypertension that may contribute to long-term cardiovascular and neurocognitive outcomes in this population.

Effect of Upright Posture on Endothelial Function in Women and Men

Women are more prone to orthostatic intolerance compared to men and have a greater vasodilatory capacity. We investigated the hypothesis that women would have greater peripheral flow-mediated dilation (FMD) while in the upright posture compared to men, which could contribute to this phenomenon. In young healthy women (age: 20 ± 3, BMI: 27 ± 5 kg/m², n = 10) and men (age = 21 ± 2, BMI: 27 ± 8 kg/m², n = 8), we assessed FMD of the brachial artery and hemodynamics to determine endothelial function during the supine and 70° head-up tilt postures (randomized). The brachial artery was kept at heart level in both trials. We observed that FMD increased in both sexes during tilt (Women: 11.9 ± 5.3 to 15.7 ± 5.6%; Men: 8.4 ± 3.2 to 14.6 ± 3.4%, Main effect of tilt p = 0.005) which was not due to changes in blood pressure or shear stress. There were no interaction effects between sex and posture. In a second cohort of women (age: 22 ± 3, BMI: 23 ± 3 kg/m², n = 9) and men (age: 22 ± 2, BMI: 25 ± 8 kg/m², n = 8), we investigated reactive hyperemia by peripheral arterial tonometry (LnRHI) via EndoPAT. Interestingly, we found that the EndoPAT response was decreased in both sexes during tilt (LnRHI: Men: 0.70 ± 0.28 to 0.59 ± 0.40, Women: 0.52 ± 0.23 to 0.30 ± 0.32, Main effect of tilt p = 0.037). We previously found that FMD is related to coronary responses to acetylcholine and adenosine whereas EndoPAT is related to coronary responses to dobutamine. Therefore, we suggest that sympathetic mediated dilation is attenuated in the upright posture while the increased vasodilatory response as measured by FMD in the tilt posture could be attributed to increasing metabolite production from postural muscles.

Biophysical Markers of Suspected Preeclampsia, Fetal Growth Restriction and the Two Combined—How Accurate They Are?

Objectives—To conduct a secondary analysis of prediction accuracy of biophysical markers for suspected Preeclampsia (PE), Fetal Growth Restriction (FGR) and the two combined near delivery in a Slovenian cohort. Methods—This was a secondary analysis of a database of a total 125 Slovenian pregnant women attending a high-risk pregnancy clinic due to suspected PE (n = 31), FGR (n = 16) and PE + FGR (n = 42) from 28–39 weeks gestation and their corresponding term (n = 21) and preterm (PTD, n = 15) controls. Data for Mean Arterial blood Pressure (MAP) and Uterine artery pulsatility index (UtA PI) estimated by Doppler sonography were extracted from the database of patients who were tested at admission to the high-risk clinic with the suspected complications. The reactive hyperemia index (RHI), and the Augmentation Index (AIX%) were extracted from the patient database using measured values obtained with the assistance of the Endo PAT, a device set to measure the signal of the peripheral arterial tone (PAT) from the blood vessels endothelium. Linear regression coefficients, Box and Whisker plots, Area under the Curve (AUC) of receiver Operation Characteristic (ROC) curves, and multiple regression were used to assess the marker accuracy using detection rate (DR) and false-positive rate (FPR) and previously reported cut-offs for estimating the positive and negative predictive value (NPV and PPV). The SPSS non-parametric statistics (Kruskal Wallis and Mann–Whitney) and Spearman’s regression coefficient were used to assess marker accuracy; p < 0.05 was considered significant. Results—MAP values reached diagnostic accuracy (AUC = 1.00, DR = 100%) for early PE cases delivered < 34, whereas UtA Doppler PI values yielded such results for early FGR < 34 weeks and the two combined reached such accuracy for PE + FGR. To reach diagnostic accuracy for all cases of the complications, the Endo PAT markers with values for MAP and UtA Doppler PI were required for cases near delivery. Multiple regression analyses showed added value for advanced maternal age and gestational week in risk assessment for all cases of PE, FGR, and PE + FGR. Spearman’s regression coefficient yielded r > 0.6 for UtA Doppler PI over GA for PE and FGR, whereas for RHI over BMI, the regression coefficient was r > 0.5 (p < 0.001 for each). Very high correlations were also found between UtA Doppler PI and sFlt-1/PlGF or PlGF (r = −0.495, p < 0.001), especially in cases of FGR. Conclusion—The classical biophysical markers MAP and UtA Doppler PI provided diagnostic accuracy for PE and FGR < 34 wks gestation. A multiple biophysical marker analysis was required to reach diagnostic accuracy for all cases of these complications. The UtA Doppler PI and maternal serum sFlt-1/PlGF or PlGF were equally accurate for early cases to enable the choice of the markers for the clinical use according to the more accessible method.

Advances in the Role of Endothelial Cells in Cerebral Small Vessel Disease

Cerebral small vessel disease (CSVD) poses a serious socio-economic burden due to its high prevalence and severe impact on the quality of life of elderly patients. Pathological changes in CSVD mainly influence small cerebral arteries, microarteries, capillaries, and small veins, which are usually caused by multiple vascular risk factors. CSVD is often identified on brain magnetic resonance imaging (MRI) by recent small subcortical infarcts, white matter hyperintensities, lacune, cerebral microbleeds (CMBs), enlarged perivascular spaces (ePVSs), and brain atrophy. Endothelial cell (EC) dysfunction is earlier than clinical symptoms. Immune activation, inflammation, and oxidative stress may be potential mechanisms of EC injury. ECs of the blood–brain–barrier (BBB) are the most important part of the neurovascular unit (NVU) that ensures constant blood flow to the brain. Impaired cerebral vascular autoregulation and disrupted BBB cause cumulative brain damage. This review will focus on the role of EC injury in CSVD. Furthermore, several specific biomarkers will be discussed, which may be useful for us to assess the endothelial dysfunction and explore new therapeutic directions.

Theoretical and Experimental Study on Assessment of Flow-Mediated Dilatation Using the Cuff Method in Brachial Arteries

Endothelial dysfunction has been shown to be an important risk factor in the pathogenesis of atherosclerosis, hypertension, and heart failure. The flow-mediated vasodilation (FMD) of the peripheral arteries is an endothelium-dependent function, which is assessed by measuring the diameter change in the brachial artery before and after ischemic stress. Brachial-artery ultrasound scanning (BAUS) is the gold standard for assessing the FMD in clinical practice. However, ultrasonography requires an operator or physician with a professional training to perform accurate measurement of the diameter of the brachial artery. Thus, some studies have used the cuff method to measure the FMD in percentage, the value of which is significantly larger than that using BAUS. The goal of this study was to explore this phenomenon. We explain the interaction between the volume changes (oscillation magnitudes in volume due to cardiac pulsations) of the artery and cuff bladder under different transmural pressures when a sphygmomanometer is wrapped around an upper arm. The compliance of the cuff bladder would be of a fixed value when the cuff pressure is low. The cuff-volume change could be replaced with a cuff-pressure change (oscillation magnitude in cuff pressure due to cardiac pulsation). With the cuff method, the FMDc could be assessed with pressure changes. Then, an inequality formula regarding FMD values by both BAUS (FMDu) and the cuff method (FMDc) was derived; FMDc > 2*FMDu + FMDu2. In order to experimentally verify this inequality formula, fifty-one subjects, including thirty-eight healthy adults and thirteen patients with hypertension, participated in this study. The systolic and diastolic diameters of their brachial arteries and cuff-pressure changes due to cardiac pulsations were separately measured by BAUS and a pressure sensor before and after an ischemic stress. The results showed that FMDu and FMDc were 8.1 ± 4.3% and 121.6 ± 48.6% in the healthy group and 4.5 ± 1.1% and 55.2 ± 22.8% in the patient group, respectively. Thus, the experimental findings comply with the theoretically derived inequality formula.

The Beneficial Effects of Astaxanthin on Glucose Metabolism and Modified Low-Density Lipoprotein in Healthy Volunteers and Subjects with Prediabetes

Astaxanthin (ASTX) is an antioxidant agent. Recently, its use has been focused on the prevention of diabetes and atherosclerosis. We examined the effects of astaxanthin supplementation for 12 weeks on glucose metabolism, glycemic control, insulin sensitivity, lipid profiles and anthropometric indices in healthy volunteers including subjects with prediabetes with a randomized, placebo-controlled trial. Methods: We enrolled 53 subjects who met our inclusion criteria and administered them with 12 mg astaxanthin or a placebo once daily for 12 weeks. Subsequently, their HbA1c levels, lipid profiles and biochemical parameters were determined. The participants also underwent a 75 g oral glucose tolerance test (OGTT), vascular endothelial function test and measurement of the visceral fat area. Results: After astaxanthin supplementation for 12 weeks, glucose levels after 120 min in a 75 g OGTT significantly decreased compared to those before supplementation. Furthermore, the levels of HbA1c (5.64 ± 0.33 vs. 5.57 ± 0.39%, p < 0.05), apo E (4.43 ± 1.29 vs. 4.13 ± 1.24 mg/dL, p < 0.05) and malondialdehyde-modified low-density lipoprotein (87.3 ± 28.6 vs. 76.3 ± 24.6 U/L, p < 0.05) were also reduced, whereas total cholesterol (TC), triglyceride (TG) and high-density lipoprotein-C (HDL-C) levels were unaltered. The Matuda index, which is one of the parameters of insulin resistance, was improved in the ASTX group compared to that before supplementation. Conclusions: our results suggest that ASTX may have preventive effects against diabetes and atherosclerosis and may be a novel complementary treatment option for the prevention of diabetes in healthy volunteers, including subjects with prediabetes, without adverse effects.

Clinical assessment of endothelial function in heart failure with preserved ejection fraction: A meta-analysis with meta-regressions

BACKGROUND

Endothelial dysfunction is a key mechanism in the development of cardiac remodelling and diastolic dysfunction in heart failure with preserved ejection fraction (HFpEF). Flow-mediated (FMD) and nitrate-mediated dilation (NMD) are noninvasive methods to assess endothelial function. We performed a meta-analysis evaluating the impact of HFpEF on FMD and NMD.

METHODS

PubMed, Web of Science, Scopus and EMBASE databases were systematically searched according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Differences were expressed as mean difference (MD) with 95% confidence intervals (95%CI). The random effects method was used.

RESULTS

A total of seven studies were included in the final analysis, 7 with data on FMD (326 HFpEF patients and 417 controls) and 3 on NMD (185 HFpEF patients and 271 controls). Compared to controls, HFpEF patients showed significantly lower FMD (MD: -1.929; 95%CI: -2.770, -1.088; P < .0001) and NMD values (MD: -2.795; 95%CI: -3.876, -1.715; P < .0001). Sensitivity analyses substantially confirmed results. Meta-regression models showed that increasing differences in E/A ratio (Z-score: -2.002; P = .045), E/E' ratio (Z-score: -2.181; P = .029) and left atrial diameter (Z-score: -1.951; P = .050) were linked to higher differences in FMD values between cases and controls.

CONCLUSIONS

Impaired endothelial function can be documented in HFpEF, with the possibility of a direct association between the severity of diastolic and endothelial dysfunction. Targeting endothelial dysfunction through pharmacological and rehabilitation strategies may represent an attractive therapeutic option.

Ten things to know about ten imaging studies: A preventive cardiology perspective ("ASPC top ten imaging")

Knowing the patient's current cardiovascular disease (CVD) status, as well as the patient's current and future CVD risk, helps the clinician make more informed patient-centered management recommendations towards the goal of preventing future CVD events. Imaging tests that can assist the clinician with the diagnosis and prognosis of CVD include imaging studies of the heart and vascular system, as well as imaging studies of other body organs applicable to CVD risk. The American Society for Preventive Cardiology (ASPC) has published "Ten Things to Know About Ten Cardiovascular Disease Risk Factors." Similarly, this "ASPC Top Ten Imaging" summarizes ten things to know about ten imaging studies related to assessing CVD and CVD risk, listed in tabular form. The ten imaging studies herein include: (1) coronary artery calcium imaging (CAC), (2) coronary computed tomography angiography (CCTA), (3) cardiac ultrasound (echocardiography), (4) nuclear myocardial perfusion imaging (MPI), (5) cardiac magnetic resonance (CMR), (6) cardiac catheterization [with or without intravascular ultrasound (IVUS) or coronary optical coherence tomography (OCT)], (7) dual x-ray absorptiometry (DXA) body composition, (8) hepatic imaging [ultrasound of liver, vibration-controlled transient elastography (VCTE), CT, MRI proton density fat fraction (PDFF), magnetic resonance spectroscopy (MRS)], (9) peripheral artery / endothelial function imaging (e.g., carotid ultrasound, peripheral doppler imaging, ultrasound flow-mediated dilation, other tests of endothelial function and peripheral vascular imaging) and (10) images of other body organs applicable to preventive cardiology (brain, kidney, ovary). Many cardiologists perform cardiovascular-related imaging. Many non-cardiologists perform applicable non-cardiovascular imaging. Cardiologists and non-cardiologists alike may benefit from a working knowledge of imaging studies applicable to the diagnosis and prognosis of CVD and CVD risk - both important in preventive cardiology.

Arterial elasticity, endothelial function and intracranial vascular health: A multimodal MRI study

Vascular dysfunctions, including arterial stiffness and endothelial dysfunction, are prevalent in hypertensive subjects. We aimed to study their relations to subclinical intracranial vascular health in this study. A total of 200 older hypertensive males without overt cardiovascular or cerebrovascular diseases were recruited. Arterial elasticity was measured as carotid-femoral pulse wave velocity (cfPWV) and endothelial function was measured as digital reactive hyperemia index (RHI). Cerebrovascular health was evaluated using MRI in four aspects: intracranial atherosclerosis, brain perfusion as cerebral blood flow (CBF), vascular rarefaction analyzed as visible arterial branches on angiography using a custom-developed analysis technique and small vessel disease measured as white matter hyperintensity (WMH). There was a significant negative association between cfPWV and CBF, suggesting a link between arterial stiffness and CBF decline. Higher cfPWV was also associated with presence of intracranial stenotic plaque and greater WMH volume. RHI was positively related to CBF, indicating that endothelial dysfunction was associated with reduced CBF. All the associations remained significant after adjustment for confounding variables. Arterial stiffness and endothelial dysfunction are associated with reduced brain perfusion in older hypertensive males. Arterial stiffness is also associated with global cerebral vascular injury, affecting both small and medium-to-large arteries.

Exposure to household air pollutants and endothelial dysfunction in rural Bangladesh: A cross-sectional study

More than one third of world's population use biomass fuel for cooking that has been linked to an array of adverse health hazards including cardiovascular mortality and morbidity. As part of Bangladesh Global Environmental and Occupational Health (GEO Health) project, we assessed whether household air pollution (HAP) was associated with dysfunction in microvascular circulation (measured by reactive hyperemia index [RHI]).

METHODS

We measured exposure to HAP (particulate matter [PM2.5], carbon monoxide [CO], and black carbon [BC]) for 48 hours of 200 healthy nonsmoker adult females who used biomass fuel for cooking. Exposure to PM2.5 and BC were measured using personal monitor, RTI MicroPEM (RTI International, NC) with an internal filter that had been both pre- and post-weighed to capture the deposited pollutants concentration. Lascar CO logger was used to measure CO. Endothelial function was measured by forearm blood flow dilatation response to brachial artery occlusion using RHI based on peripheral artery tonometry. A low RHI score (<1.67) indicates impaired endothelial function.

RESULTS

Average 48 hours personal exposure to PM2.5 and BC were 144.15 μg/m3 (SD 61.26) and 6.35 μg/m3 (SD 2.18), respectively. Interquartile range for CO was 0.73 ppm (0.62-1.35 ppm). Mean logarithm of RHI (LnRHI) was 0.57 in current data. No statistically significant association was observed for LnRHI with PM2.5 (odds ratio [OR] = 0.97; 95% confidence interval [CI] = 0.92, 1.01; P = 0.16), BC (OR = 0.85; 95% CI = 0.72, 1.01; P = 0.07), and CO (OR = 0.89; 95% CI = 0.64, 1.25; P = 0.53) after adjusting for potential covariates.

CONCLUSIONS

In conclusion, HAP was not associated with endothelial dysfunction among nonsmoking females in rural Bangladesh who used biomass fuel for cooking for years.

High-sodium diet does not worsen endothelial function in female patients with postural tachycardia syndrome

PURPOSE

Postural tachycardia syndrome (POTS), a syndrome characterized by orthostatic symptoms and a heart rate increase of at least 30 beats per minute in the absence of hypotension upon standing, is often accompanied by increased sympathetic activity and low blood volume. A common non-pharmacologic recommendation for patients with POTS is a high-sodium (HS) diet with the goal of bolstering circulating blood volume. The objective of this study is to assess the effects of 6 days of a HS diet on endothelial function in POTS.

METHODS

A total of 14 patients with POTS and 13 age-matched healthy controls, all females, were studied following 6 days on a low-sodium (LS) diet (10 mEq/day) and 6 days on a HS diet (300 mEq/day) in a crossover design. We measured endothelial function following reactive hyperemia in the brachial artery using flow-mediated dilation (FMD), leg blood flow (LBF) using strain gauge plethysmography in the calf, and reactive hyperemic index (RHI) in the microcirculation of the hand using pulsatile arterial tonometry.

RESULTS

On the LS diet, FMD% did not differ between patients with POTS and the healthy controls although peak brachial artery diameter was lower for the patient group. RHI was higher for the patient group than for the controls, but there were no differences in post-ischemic LBF increase. On the HS diet, there were no between-group differences in FMD%, LBF increase, or RHI.

CONCLUSION

In summary, a HS diet for 6 days did not induce endothelial dysfunction. This non-pharmacologic treatment used for patients with POTS does not negatively affect endothelial function when used for a sub-acute duration.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01550315; March 9, 2012.

Comparison of biomarkers of endothelial dysfunction and microvascular endothelial function in patients with primary aldosteronism and essential hypertension

Introduction:

Studies have shown that primary aldosteronism (PA) has a higher risk of cardiovascular events than essential hypertension (EH). Endothelial dysfunction is an independent predictor of cardiovascular events. Whether PA and EH differ in the endothelial dysfunction is uncertain. Our study was designed to investigate the levels of biomarkers of endothelial dysfunction (Asymmetric dimethylarginine, ADMA; E-selectin, and Plasminogen activator inhibitor-1, PAI-1) and assess the microvascular endothelial function in patients with PA and EH, respectively.

Methods:

The biomarkers of endothelial dysfunction were measured by enzyme-linked immunosorbent assay (ELISA). Microvascular endothelial function was evaluated by Pulse amplitude tonometry (PAT).

Results:

Thirty-one subjects with EH and 36 subjects with PA including 22 with aldosterone-producing adenoma (APA) and 14 with idiopathic hyperaldosteronism (IHA) were enrolled in our study. The ADMA levels among the three groups were different (APA 47.83 (27.50, 87.74) ng/ml vs EH 25.08 (22.44, 39.79) ng/ml vs IHA 26.00 (22.23, 33.75) ng/ml; p = 0.04), however, when the APA group was compared with EH and IHA group, there was no statistical significance (47.83 (27.50, 87.74) ng/ml vs 25.08 (22.44, 39.79) ng/ml for EH, p = 0.11; 47.83 (27.50, 87.74) ng/ml vs IHA 26.00 (33.75) ng/ml, p = 0.07). The results of ADMA levels are presented as Median (p25, p75). Whereas, levels of PAI-1 and E-selectin, microvascular endothelial function were not significantly different between PA and EH subjects.

Conclusions:

Our study shows no significant differences between PA and EH in terms of biomarkers of endothelial dysfunction and microvascular endothelial function. The microvascular endothelial function of PA and EH patients is comparable.

Systemic Inflammation, Vascular Function, and Endothelial Progenitor Cells after an Exercise Training Intervention in COPD

BACKGROUND

Exercise training is a cornerstone of the treatment of chronic obstructive pulmonary disease (COPD) in all disease stages. Data about the training effects with supplemental oxygen in nonhypoxemic patients remains inconclusive. In this study we set out to investigate the training and oxygen effects on inflammatory markers, vascular function, and endothelial progenitor cells in this population of increased cardiovascular risk.

METHODS

In this prospective, randomized, double-blind, crossover study, 29 patients with nonhypoxemic COPD performed combined endurance and strength training 3 times a week while breathing medical air or supplemental oxygen for the first 6-week period, and were then reallocated to the opposite gas for the following 6 weeks. Exercise capacity, inflammatory biomarkers, endothelial function (peripheral arterial tone analysis), and endothelial progenitor cells were assessed. Data were also analyzed for a subgroup with endothelial dysfunction (reactive hyperemia index <1.67).

RESULTS

Following 12 weeks of exercise training, patients demonstrated a significant improvement of peak work rate and an associated decrease of blood fibrinogen and leptin. Eosinophils were found significantly reduced after exercise training in patients with endothelial dysfunction. In this subgroup, peripheral arterial tone analysis revealed a significant improvement of reactive hyperemia index. Generally, late endothelial progenitor cells were found significantly reduced after the exercise training intervention. Supplemental oxygen during training positively influenced the effect on exercise capacity without impact on inflammation and endothelial function.

CONCLUSIONS

This is the first randomized controlled trial in patients with COPD to show beneficial effects of exercise training not only on exercise capacity, but also on systemic/eosinophilic inflammation and endothelial dysfunction.

Endothelial Vasodilation After a High-Volume Training Load and Tapered Training in Collegiate Female Swimmers

ABSTRACT

Weihl, FM and Van Guilder, GP. Endothelial vasodilation after a high-volume training load and tapered training in collegiate female swimmers. J Strength Cond Res 35(3): 811-818, 2021-High-volume endurance training loads have been linked to adverse remodeling of the heart and large arteries; yet, data on the vascular endothelial function are unclear. Moreover, although collegiate-level endurance athletes often perform high-volumes of vigorous endurance training and resistance training as part of their strength and conditioning programs, it is unknown whether they also experience vascular abnormalities, particularly changes in endothelial function. The aim of this study was to verify the impact of a high-volume training load phase followed by low-volume tapered training on endothelial vasodilator function in National Collegiate Athletic Association (NCAA) Division I competitive female swimmers. Microvascular endothelial vasodilation was assessed by pulse arterial tonometry that provides a reactive hyperemia index in 10 female NCAA Division 1 swimmers after 4 weeks of a high-volume training load, and subsequently, after 3 weeks of low-volume tapered training as part of preparation for annual conference championships. The reactive hyperemia index was calculated as the ratio of the pulse volume amplitude after 5 minutes of left-arm brachial artery ischemia to the baseline amplitude, divided by same ratio in the contralateral arm. The high-volume training load included a 4-week block of dual-day sessions (120 minutes per practice) consisting of vigorous intensity endurance and high-intensity interval/sprint swim training, coupled with 5K running, resistance training, and Olympic weightlifting. Tapered training consisted of 3 weeks of 3-5 swims per week at ∼50% V̇o2max for 60 minutes per practice (∼4,000 minutes per practice). The reactive hyperemia index (1.73 ± 0.50) was low in athletes after the high-volume training load with 8 athletes demonstrating endothelial dysfunction. However, after tapered training, the reactive hyperemia index was ∼33% higher (2.29 ± 0.43; 95% confidence interval [CI]: 1.98-2.60, p = 0.0223 vs. the high-volume training load). Effect size, as expressed by the partial eta2 (0.46) and Cohen's dz (1.1923; 95% CI: 0.1687-2.4643) with tapered training, was large. These results demonstrate distinct differences in endothelial vasodilation after 4 weeks of a high-volume training load compared with a 3-week taper in NCAA Division I female swimmers.

Standard exercise stress testing attenuates peripheral microvascular function in patients with suspected coronary microvascular dysfunction

BACKGROUND

The effect of exercise on the microvasculature of patients with suspected coronary microvascular dysfunction (CMD), assessed by reactive hyperemia peripheral arterial tonometry (RH-PAT; EndoPAT), is unknown. The present study aimed to determine if standard clinical exercise stress testing (GXT) affected peripheral microvascular function, as determined by the reactive hyperemia index (RHI and LnRHI), in patients with suspected CMD.

METHODS

In a cross-sectional study, patients (n = 76) were grouped based on whether the GXT was performed; 1) prior to (exercisers; n = 30), or 2) after the vascular assessment (non-exercisers; n = 46). Patients with an adenosine index of microvascular resistance > 25, adenosine coronary flow reserve (CFR) < 2.0, and/or acetylcholine CFR < 1.5 were considered to have CMD (n = 42). RHI and LnRHI quantified finger pulse amplitude hyperemia following 5 min of forearm ischemia.

RESULTS

LnRHI was lower in patients with CMD compared to patients without CMD, while LnRHI was also lower in exercisers compared to non-exercisers (LnRHI: CMD Non-Exercisers: 0.63 ± 0.25; CMD Exercisers: 0.54 ± 0.19; No CMD Non-Exercisers: 0.85 ± 0.23; No CMD Exercisers: 0.63 ± 0.26; Condition and Exercise Main Effects: Both P < 0.01). In patients who did not exercise prior to the vascular assessment, the receiver operating characteristic curve (ROC) for LnRHI to predict CMD was 0.76 (95% CI: 0.62-0.91; P < 0.01). However, in patients who performed exercise prior to the vascular assessment, the ROC for LnRHI to predict CMD was 0.60 (95% CI: 0.40-0.81; P = 0.34).

CONCLUSIONS

CMD is associated with impaired peripheral microvascular function and preceding acute exercise is associated with further reductions of LnRHI. Further, acute exercise abolished the capacity for RH-PAT to predict the presence of CMD in patients with chest pain and non-obstructive coronary arteries. RH-PAT measurements in patients with suspected CMD should not be conducted after exercise has been performed.

The effect of remote ischaemic preconditioning on endothelial function after hip fracture surgery

BACKGROUND

Endothelial dysfunction seems to play a role in the pathophysiology of myocardial injury after surgery. The aim of this randomised clinical trial was to examine whether remote ischaemic preconditioning in relation to hip fracture surgery ameliorates post-operative systemic endothelial dysfunction.

METHODS

This was a planned single-centre pilot sub-study of a multicentre, randomised clinical trial. Patients ≥45 years with a cardiovascular risk factor were randomised to remote ischaemic preconditioning (RIPC) or control (standard treatment) performed in relation with their hip fracture operation. RIPC consisted of four cycles of 5 minutes forearm ischaemia and reperfusion. The procedure was performed non-invasively with a tourniquet. The endothelial function was assessed with non-invasive digital pulse amplitude tonometry on post-operative day 1 and expressed as the reactive hyperaemia index (RHI). Endothelial dysfunction was defined as RHI < 1.22.

RESULTS

Between February 2015 and December 2016, 18 patients were allocated to the RIPC group and 20 patients to the control group. The endothelial function was impaired in both groups on post-operative day 1. RHI did not differ between the groups, 1.47 (95% CI 1.20-1.75) in the RIPC group vs. 1.54 (95% CI 1.17-1.91) in the control group, P = .76. Endothelial dysfunction was present in 3/18 patients (16.7%) in the RIPC group and 8/20 patients (40%) in the control group, P = .11.

CONCLUSION

No beneficial effect of remote ischaemic preconditioning on the systemic endothelial dysfunction, assessed at a single time point on post-operative day one, was detected after hip fracture surgery.

Impaired Endothelial Function in Patients With Postural Tachycardia Syndrome

The purpose of this study is to evaluate endothelial function in postural tachycardia syndrome (PoTS), a poorly understood chronic condition characterized by a state of consistent orthostatic tachycardia (delta heart rate ≥30 beats per minute) upon standing without orthostatic hypotension. Nineteen patients with PoTS and 9 healthy controls were studied after 3 days of a fixed, caffeine-free, normal sodium (150 milliequivalents/day) diet. All participants underwent autonomic function testing, including sinus arrhythmia, valsalva maneuver, hyperventilation, cold pressor, handgrip, and a standing test with catecholamine measurements, followed by endothelial function testing. We analyzed 3 measures of endothelial function: percent brachial flow-mediated dilation, digital pulsatile arterial tonometry, and postischemic percent leg blood flow. Flow-mediated dilation was significantly lower in patients with PoTS (6.23±3.54% for PoTS) than in healthy controls (10.6±4.37% for controls versus, P=0.014). PoTS and controls had similar digital pulsatile arterial tonometry (1.93±0.40 arbitrary units for controls versus 2.13±0.63 arbitrary units for PoTS). PoTS had similar but suggestive percent leg blood flow to controls (313±158% for PoTS versus 468±236% for controls, P=0.098). Patients with PoTS have significantly reduced flow-mediated dilation compared with healthy controls, suggesting that PoTS is characterized by endothelial dysfunction in conduit arteries. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01308099.

Reduced effect of ischemic preconditioning against endothelial ischemia-reperfusion injury with cardiovascular risk factors in humans

The extent that clustered CVD risk factors interfere with ischemic preconditioning (IPC) to protect against microvascular endothelial dysfunction with ischemia-reperfusion (I/R) injury in humans is unclear. We hypothesized that adults with a clustered burden of ≥3 CVD risk factors would demonstrate a reduced capacity of IPC to protect endothelial function with I/R injury. Twenty-two (age: 45 ± 14 year) adults [12 healthy controls; 10 raised risk (10-year FRS risk score ~3%)] were studied using a 2 × 2 randomized cross-over design. Pulse arterial tonometry was used to assess microvascular endothelium-dependent vasodilation during reactive hyperemia in response to endothelial I/R injury (20 min brachial artery occlusion/45 min reperfusion) that was preceded by remote IPC (3 × 5 min ischemia/reperfusion) or mock IPC. In both groups, microvascular reactive hyperemia was reduced ~20% (both P < 0.01) after endothelial I/R injury without remote IPC. However, in control subjects remote IPC prevented endothelial I/R injury (from baseline reactive hyperemic ratio: 2.1 ± 0.4 AU to post I/R injury: 2.5 ± 0.5 AU; P = 0.09). In contrast, the reactive hyperemia ratio in raised risk subjects was significantly reduced from 2.2 ± 0.6 AU to 1.9 ± 0.5 AU (P = 0.0087) despite attempts to induce protection by remote IPC, with the magnitude of reduction similar to their mock IPC trial. The magnitude of remote IPC-mediated endothelial protection against I/R injury was inversely related to the number of risk factors. CVD risk factors diminish the effect of IPC to protect the microvasculature from I/R injury in humans. Translating IPC to clinical practice for vasculoprotection will continue to be challenging in patients with increased CVD risk.

Effect of skin optical absorption on speckleplethysmographic (SPG) signals

Recent advances in optical technology have emerged for measuring blood flow in the extremities using speckleplethysmography (SPG), which may address needs in vascular medicine and other fields. SPG has demonstrated a highly linear response with flow rate, but the susceptibility to differences in skin tone is unclear. Two validation studies using skin-simulating phantoms and a simple clinical protocol were conducted to determine the impact of absorbing skin layers on SPG measurements. Benchtop results demonstrated that the coefficient of determination between known flow rate and SPG was highly linear (R² = 0.990) and was unaffected by the addition of skin-phantom layers with variable absorption (R² = 0.996-0.999). Additionally, no significant trend was found between the fit residuals of SPG and flow rate with increasing skin-phantom absorption (R²=0.025, p = 0.29). In clinical testing, no significant difference was found using both a 4-way ANOVA between demographic classifications (F = 0.89, p = 0.45), and a 2-way ANOVA test between lower- and higher-melanin subclassifications (F = 0.4, p = 0.52).

Association of endothelial dysfunction with incident prediabetes, type 2 diabetes and related traits: the KORA F4/FF4 study

INTRODUCTION

Peripheral arterial tonometry (PAT) is an operator-independent and non-invasive measurement method to assess microvascular endothelial function in the fingertips. PAT-derived measures of endothelial function were associated with type 2 diabetes in cross-sectional studies. However, longitudinal studies are lacking. The study aims to investigate the association of two PAT-derived endothelial function parameters reactive hyperemia index (RHI) and mean baseline amplitude (MBA) with follow-up glucose and insulin parameters and the development of (pre)diabetes and type 2 diabetes.

RESEARCH DESIGN AND METHODS

The study included 673 participants initially without diabetes (328 men and 345 women) aged 52-71 years from the prospective population-based Cooperative Health Research in the Region of Augsburg F4/FF4 cohort study conducted in Southern Germany (baseline examination F4: 2006-2008; follow-up FF4: 2013-2014). An oral glucose tolerance test was performed at baseline and follow-up to define type 2 diabetes, prediabetes, fasting glucose, fasting insulin, 2-hour glucose, homeostasis model assessment of insulin resistance (HOMA-IR), homeostasis model assessment of beta-cell function and hemoglobin A1c.

RESULTS

In multivariable adjusted logistic/linear regression models, a 1 SD increase in baseline RHI was inversely associated with incident type 2 diabetes (OR 0.69 (95% CI 0.48 to 0.97)) as well as with fasting insulin (β -0.069 (95% CI -0.131 to -0.007)) and HOMA-IR (β -0.072 (95% CI -0.133 to -0.010)) at follow-up in participants with initial normoglycemia. A 1 SD increase in baseline MBA was positively associated with incident (pre)diabetes (OR 1.62 (95% CI 1.25 to 2.11)) and fasting glucose (β 0.096 (95% CI 0.047 to 0.146)) at follow-up in participants with initial normoglycemia.

CONCLUSIONS

Microvascular endothelial dysfunction seems to be involved in the development of early derangements in glucose metabolism and insulin resistance and could thereby trigger the development of prediabetes and type 2 diabetes.

Role of Gender and Physical Activity Level on Cardiovascular Risk Factors and Biomarkers of Oxidative Stress in the Elderly

Background

Cardiovascular diseases remain as the leading cause of morbidity and mortality in industrialized countries. Ageing and gender strongly modulate the risk to develop cardiovascular diseases but very few studies have investigated the impact of gender on cardiovascular diseases in the elderly, which represents a growing population. The purpose of this study was to test the impact of gender and physical activity level on several biochemical and clinical markers of cardiovascular risk in elderly individuals.

Methods

Elderly individuals (318 women (75.8 ± 1.2 years-old) and 227 men (75.8 ± 1.1 years-old)) were recruited. Physical activity was measured by a questionnaire. Metabolic syndrome was defined using the National Cholesterol Education Program Expert Panel's definition. Polysomnography and digital tonometry were used to detect obstructive sleep apnea and assess vascular reactivity, respectively. Blood was sampled to measure several oxidative stress markers and adhesion molecules.

Results

The frequency of cardiovascular diseases was significantly higher in men (16.4%) than in women (6.1%) (p < 0.001). Body mass index (25.0 ± 4.3 vs. 25.8 ± 3.13 kg.m⁻²) and glycaemia (94.9 ± 16.5 vs. 101.5 ± 22.6 mg.dL⁻¹) were lower, and High Density Lipoprotein (HDL) (74.6 ± 17.8 vs. 65.0 ± 17.2 mg.dL⁻¹) was higher in women compared to men (p < 0.05). Oxidative stress was lower in women than in men (uric acid: 52.05 ± 13.78 vs. 59.84 ± 13.58, advanced oxidation protein products: 223 ± 94 vs. 246 ± 101 μmol.L⁻¹, malondialdehyde: 22.44 ± 6.81 vs. 23.88 ± 9.74 nmol.L⁻¹). Physical activity was not associated with lower cardiovascular risk factors in both genders. Multivariate analyses showed an independent effect of gender on acid uric (β = 0.182; p = 0.020), advanced oxidation protein products (β = 0.257; p < 0.001), and HDL concentration (β = −0.182; p = 0.026).

Conclusion

These findings suggest that biochemical cardiovascular risk factors are lower in women than men which could explain the lower cardiovascular disease proportion observed in women in the elderly.

Novel Biomarkers for Evaluation of Endothelial Dysfunction

Endothelial dysfunction is one of the earliest indicators of cardiovascular (CV) dysfunction, and its evaluation would be of considerable importance to stratify CV risk of many diseases and to assess the efficacy of atheroprotective treatments. Flow-mediated dilation is the most widely used method to study endothelial function. However, it is operator-dependent and can be influenced by physiological variations. Circulating biomarkers are a promising alternative. Due to the complexity of endothelial function, many of the biomarkers studied do not provide consistent information about the endothelium when measured alone. New circulating markers are being explored and some of them are thought to be suitable for the clinical setting. In this review, we focus on novel biomarkers of endothelial dysfunction, particularly endothelial microparticles, endocan, and endoglin, and discuss whether they fulfill the criteria to be applied in clinical practice.

Reactive hyperemia: a review of methods, mechanisms, and considerations

Reactive hyperemia is a well-established technique for noninvasive assessment of peripheral microvascular function and a predictor of all-cause and cardiovascular morbidity and mortality. In its simplest form, reactive hyperemia represents the magnitude of limb reperfusion following a brief period of ischemia induced by arterial occlusion. Over the past two decades, investigators have employed a variety of methods, including brachial artery velocity by Doppler ultrasound, tissue reperfusion by near-infrared spectroscopy, limb distension by venous occlusion plethysmography, and peripheral artery tonometry, to measure reactive hyperemia. Regardless of the technique used to measure reactive hyperemia, blunted reactive hyperemia is believed to reflect impaired microvascular function. With the advent of several technological advancements, together with an increased interest in the microcirculation, reactive hyperemia is becoming more common as a research tool and is widely used across multiple disciplines. With this in mind, we sought to review the various methodologies commonly used to assess reactive hyperemia and current mechanistic pathways believed to contribute to reactive hyperemia and reflect on several methodological considerations.

Endothelial dysfunction and arterial stiffness in patients with systemic lupus erythematosus: A systematic review and meta-analysis

BACKGROUND AND AIMS

Non-invasive surrogates of cardiovascular (CV) disease such as endothelial dysfunction (ED) and peripheral arterial stiffness (AS) have been evaluated in systemic lupus erythematosus (SLE) patients. The aim of this study was to systematically review and meta-analyze reports of cardiovascular disease (CVD) in SLE patients, as measured by ED and AS.

METHODS

Studies analyzing the relationship of SLE with ED (flow-mediated dilatation [FMD], nitroglycerin-mediated dilatation [NMD] and peripheral arterial tonometry [PAT]) and AS (augmentation index [AIx], pulse wave velocity [PWV]) were systematically searched for in PubMed, Cochrane library, EMBASE, VHL, SciELO and Web of Science databases. Inclusion criteria included peer-review and English language. Mean differences (MD) and 95% confidence intervals (CIs) were estimated using the random effect model. The study was registered with PROSPERO, number CRD42019121068.

RESULTS

The meta-analysis included 49 studies. FMD data from 18 studies including 943 SLE subjects (mean age = 38.71 [95%CI 36.21, 41.21] years) and 644 unaffected controls (mean age = 38.63 [95%CI 36.11, 41.15] years) were included. When compared with unaffected controls, FMD in SLE subjects was decreased by 4.3% (95%CI: -6.13%, -2.47%): p < 0.001). However, NMD did not significantly differ between SLE patients and controls (MD = - 2.68%; 95% CI -6.00, 0.62; p = 0.11). A significantly increased AS between SLE patients and controls according to overall PWV (MD = 1.12 m/s; 95% CI 0.72-1.52; p < 0.001) was observed, but not for the brachial-ankle PWV. AIx was also increased in SLE patients compared with healthy controls (MD = 4.55%; 95% CI 1.48-7.63; p = 0.003).

CONCLUSIONS

Overall, SLE patients showed impaired FMD, an independent predictor of CV events. There was a higher degree of AS in SLE patients compared with controls. ED and AS in SLE should be considered when planning preventive strategies and therapies.

Establishing a Differential Marker Profile for Pregnancy Complications Near Delivery

OBJECTIVE

The aim of this work was to define a differential marker profile for pregnancy complications near delivery.

METHODS

We enrolled pregnant women who were referred to the outpatient pregnancy clinic of the University Medical Center, Ljubljana, Slovenia, due to symptoms of pregnancy complications and women with a history of pregnancy complications attending the high-risk hospital clinic for close surveillance. They were evaluated for prior risk and were tested for biophysical and biochemical markers at the time of enrolment. Biochemical markers included the pro- and anti-angiogenic markers, along with additional previously reported markers of potential value, all tested by various formats of immuno-diagnostics. Biophysical markers included blood pressure, sonographic markers, and EndoPAT. Statistical differences were determined with Kruskal-Wallis and Mann-Whitney tests for continuous parameters, and Pearson χ2 for categorical values. p < 0.05 was considered significant.

RESULTS

The cohort included 125 pregnant patients, 31 developed preeclampsia (PE) alone (13 were <34 weeks' gestation), 16 had intrauterine growth restriction (IUGR) alone (12 were <34 weeks), 42 had both IUGR and PE (22 were <34 weeks), and 15 had an iatrogenic preterm delivery (PTD; 6 were <34 weeks). Twenty-one were unaffected and delivered a healthy baby at term. Mean arterial blood pressure and proteinuria were significantly higher in PE and PE+IUGR but not in pure IUGR or PTD. In PE, IUGR, and PE+IUGR, the levels of soluble fms-like tyrosine kinase 1 (sFlt-1) and soluble endoglin (sEng) were significantly higher, while placental growth factor (PlGF) was very low compared to unaffected controls and PTD. PE, IUGR, and PE+IUGR also had a high anti-angiogenic ratio (sFlt-1/PlGF) and a low proangiogenic ratio of PlGF/(sFlt-1+Eng). Levels of inhibin A were significantly higher in pure PE across subgroups but had many extreme values, which made it a poor differentiator. Higher uterine artery Doppler pulsatility indexes were detected in PE, IUGR, and PE+IUGR, with similar resistance indexes and peaks of systolic velocity. A significantly different marker level between PE and IUGR was found using arterial stiffness that was 10 times higher in PE; concurrently with an increase of the reactive hyperemia index, both were accompanied by a slight increase in placental protein 13. Higher tumor necrosis factor alpha (TNFα) differentially identified iatrogenic very early PTD (<34 weeks).

CONCLUSION

Arterial stiffness can serve as a major marker to differentiate PE (with/without IUGR) from pure IUGR near delivery. TNFα can differentiate iatrogenic early PTD from other complications of pregnancy and term IUGR.

Reactive hyperemia and baseline pulse amplitude among smelter workers exposed to fine and ultrafine particles

Objective

Ambient exposure to fine particles is associated with increased cardiovascular morbidity and mortality. Associations between occupational particulate matter (PM) exposure and cardiovascular disease have been studied less. The objective of this study was to examine associations between PM exposure and endothelial function among workers in Norwegian smelters.

Methods

We examined endothelial function with Endo-PAT equipment after a working day (WD) and on a day off (DO) in 59 furnace workers recruited from three metal smelters in Norway. The difference in baseline pulse amplitude (BPA) and reactive hyperemia index (RHI) between the 2 days was analysed in relation to individual exposure to PM < 250 nm (PM₂₅₀) or the respirable aerosol fraction of particles, and adjusted for relevant covariates.

Results

The exposure to PM₂₅₀ ranged from 0.004 to 5.7 mg/m³. The mean BPA was significantly higher on WD relative to DO (772 vs. 535, p = 0.001). This difference was associated with PM concentrations among participants ≥ 34 years, but not among the younger workers. Reactive hyperemia was significantly lower on workdays relative to days off (1.70 vs. 1.84, p = 0.05). This difference was observed only among participants above the age 34. No associations with PM exposure were observed.

Conclusions

PM exposure was associated with higher BPA among participants older than 34 years. BPA reflects microvessel pulsatility. Our results may indicate an age-dependent cardiovascular susceptibility to PM exposure. Endothelial function measured by RHI was reduced on WD among participants 34 years and older, but we found no associations between PM exposure and RHI.

Reactive hyperemia-peripheral arterial tonometry is useful for assessment of not only endothelial function but also stenosis of the digital artery

BACKGROUND

Although reactive hyperemia-peripheral arterial tonometry (RH-PAT) is widely used for assessment of endothelial function, RH index (RHI) cannot be measured in some cases when pulse wave amplitude (PWA) is very low. Decrease in PWA is mainly caused by proper palmar digital artery (PPDA) stenosis. The purpose of this study was to evaluate the relationship between PWA measured by RH-PAT and stenosis of the PPDA measured by digital subtraction angiography and to evaluate the limitation of assessment of endothelial function measured by RHI in patients with PPDA stenosis.

METHODS

We measured baseline PWA in 51 fingers including the first to third fingers of both hands in 10 patients who had PPDA stenosis and in 66 fingers that were the first fingers of both hands in 33 subjects who had no PPDA stenosis. Severe stenosis was defined as over 75% by lower percent diameter stenosis between two PPDAs in a finger.

RESULTS

PWA was significantly correlated with stenosis of the digital artery (r=-0.55; P<0.0001). A PWV value of 300mV was the optimal cut-off value for severe stenosis (sensitivity, 84.0%; specificity, 88.5%). Log RHI was significantly lower in patients with PPDA stenosis than in subjects without PPDA stenosis (0.33±0.27 versus 0.73±0.27, P=0.007).

CONCLUSIONS

RH-PAT may be useful for assessment of not only endothelial function but also PPDA stenosis. RHI may be underestimated in patients with PPDA stenosis. We should pay attention to low baseline PWA when measuring RHI.

CLINICAL TRIAL REGISTRATION INFORMATION

URL for clinical trial: http://UMIN; registration number for clinical trial: UMIN000003409.

Endothelial function as predictor in patients with coronary syndrome treated by percutaneous coronary intervention

We aimed at identifying the predictive role of endothelial function assessed by the RH-PAT index (RHI) for future major cardiovascular events (MACEs) in acute coronary syndrome (ACS) patients treated with percutaneous coronary intervention (PCI). We measured RHI in 308 subjects with ACS, and they were divided into the normal endothelial function (NEF) group and the endothelial dysfunction (DEF) group according to the RHI. The subjects were followed up for a mean of 16 months (interquartile range [IQR]: 14–20 months) after PCI treatment, and their MACEs were also recorded. Cumulative incidence curves were constructed for time-to-event variables with Kaplan–Meier estimates and compared using the log-rank test. The overall incidence of MACEs was 25.39% in the DEF group and 15.96% in the NEF group (P<0.05). Kaplan–Meier analysis also demonstrated a significantly higher probability of MACEs in the DEF group than in the NEF group (log-rank test: P<0.05). Multivariate Cox hazard analysis identified RHI (Model 2, adjusted by blood pressure, hazard ratio [HR]: 0.425; 95% confidence interval [CI]: 0.198–0.914; P=0.029) and SYNTAX score (HR: 1.043; 95% CI: 1.019–1.067; P<0.001) as independent predictors of future MACEs after PCI treatment in ACS patients. Endothelial function measured by reactive hyperemia-peripheral arterial tonometry (RH-PAT) is impaired in ACS subjects treated with PCI. The RHI was an independent predictor of MACEs, suggesting that RHI may be useful as a candidate biomarker in the risk stratification of patients with ACS after PCI treatment.

Arginine impairs endothelial and executive function in older subjects with cardiovascular risk

Neurovascular coupling, the relationship between cerebral blood flow and neuronal activity, is attenuated in patients with impaired executive function. We tested the hypothesis that peripheral vascular function may associate with executive function in older subjects with cardiovascular risk factors and that treatment with the antioxidant L-arginine would improve both vascular and executive function. Nineteen subjects with type 2 diabetes mellitus and/or controlled hypertension were enrolled. Subjects were treated with L-arginine or placebo for 4 days in a randomized, double-blinded, cross-over study. Brachial artery vascular function, peripheral artery tonometry, and Trail Making Test Part B testing were performed on day 1 and day 4 during each condition. L-arginine significantly reduced the digital reactive hyperemia index, and the comparison of changes against placebo was significant (P = .01). With executive function testing, we observed a significant interaction between treatment and order. Restricting the analysis to the first treatment period, subjects treated with placebo decreased their Trail Making Test Part B times by 57.3 ± 52.5 seconds from day 1 to day 4 (P = .01) while those treated with arginine had no significant change (6.4 ± 18.4 seconds worse, P = .37). In addition, L-arginine was associated with increased mean arterial pressure from 88 ± 9 mm Hg to 92 ± 11 mm Hg, which trended toward significance. L-arginine treatment worsened digital microvascular and executive function in older subjects with cardiovascular risk factors. These data further support a link between vascular and executive function.

Recombinant erythropoietin acutely decreases renal perfusion and decouples the renin-angiotensin-aldosterone system

The effect of recombinant erythropoietin (rhEPO) on renal and systemic hemodynamics was evaluated in a randomized double-blinded, cross-over study. Sixteen healthy subjects were tested with placebo, or low-dose rhEPO for 2 weeks, or high-dose rhEPO for 3 days. Subjects refrained from excessive salt intake, according to instructions from a dietitian. Renal clearance studies were done for measurements of renal plasma flow, glomerular filtration rate (GFR) and the segmentel tubular handling of sodium and water (lithium clearance). rhEPO increased arterial blood pressure, total peripheral resistance, and renal vascular resistance, and decreased renal plasma flow in the high-dose rhEPO intervention and tended to decrease GFR. In spite of the decrease in renal perfusion, rhEPO tended to decrease reabsorption of sodium and water in the proximal tubule and induced a prompt decrease in circulating levels of renin and aldosterone, independent of changes in red blood cell mass, blood volumes, and blood pressure. We also found changes in biomarkers showing evidence that rhEPO induced a prothrombotic state. Our results suggest that rhEPO causes a direct downregulation in proximal tubular reabsorption that seems to decouple the activity of the renin-angiotensin-aldosterone system from changes in renal hemodynamics. This may serve as a negative feed-back mechanism on endogenous synthesis of EPO when circulating levels of EPO are high. These results demonstrates for the first time in humans a direct effect of rhEPO on renal hemodynamics and a decoupling of the renin-angiotensin-aldosterone system.

Microvascular endothelial function and cognitive performance: The ELSA-Brasil cohort study

Impaired microvascular endothelial function may be implicated in the etiology of cognitive decline. Yet, current data on this association are inconsistent. Our objective is to investigate the relation of microvascular endothelial function to cognitive performance in the ELSA-Brasil cohort study. A total of 1521 participants from ELSA-Brasil free of dementia underwent peripheral arterial tonometry (PAT) to quantify microvascular endothelial function (PAT-ratio and mean baseline pulse amplitude (BPA)) and cognitive tests that covered the domains of memory, verbal fluency, and executive function at baseline. Cognitive tests in participants aged 55 years old and above were repeated during the second examination (mean follow-up: 3.5 (0.3) years). Linear regression and generalized linear models were used to evaluate the association between endothelial function, global cognitive performance, and performance on specific cognitive domains. In unadjusted cross-sectional analyses, we found that BPA and PAT-ratio were associated with worse global cognitive performance (mean difference for BPA: -0.07, 95% CI: -0.11; -0.03, p<0.01; mean difference for PAT-ratio: 0.11, 95% CI: 0.01; 0.20, p=0.02), worse performance on learning, recall, and word recognition tests (BPA: -0.87, 95% CI: -1.21; -0.52, p<0.01; PAT-ratio: 1.58, 95% CI: 0.80; 2.36, p<0.01), and only BPA was associated with worse performance in verbal fluency tests (-0.70, 95% CI: -1.19; -0.21, p<0.01). Adjustments for age, sex, and level of education rendered the associations statistically non-significant. Longitudinally, there was no association between microvascular endothelial and cognitive functions. The associations between microvascular endothelial function and cognition are explained by age, sex, and educational level. Measures of microvascular endothelial function may be of limited value with regard to preclinical cognitive deficits.