Non-Invasive Assessment of Endothelial Function

Molecular Insights into the Relationship Between Platelet Activation and Endothelial Dysfunction: Molecular Approaches and Clinical Practice

Platelets are one of the coagulation cells. When platelet activation occurs, many mediators are released and affect endothelial cells (ECs) and lead to endothelial dysfunction (ED). ED plays an important role in the pathogenesis of many diseases, including cardiovascular disease (CVD). Platelet are of important factors in ED. The release of mediators by platelets causes the stimulation of inflammatory pathways, oxidative stress, and apoptosis, which ultimately result in ED.On the other hand, platelet activation in CVD patients can be associated with a bad prognosis. Platelet activation can increase the level of markers such as p-selectin in the serum. Also, in this study, we have discussed the role of platelet as a diagnostic factor, as well as its use as a treatment option. In addition, we discussed some of the molecular pathways that are used to target platelet activation.

Assessment of power spectral density of microvascular hemodynamics in skeletal muscles at very low and low-frequency via near-infrared diffuse optical spectroscopies

In this work, we used a hybrid time domain near-infrared spectroscopy (TD-NIRS) and diffuse correlation spectroscopy (DCS) device to retrieve hemoglobin and blood flow oscillations of skeletal muscle microvasculature. We focused on very low (VLF) and low-frequency (LF) oscillations (i.e., frequency lower than 0.145 Hz), that are related to myogenic, neurogenic and endothelial activities. We measured power spectral density (PSD) of blood flow and hemoglobin concentration in four muscles (thenar eminence, plantar fascia, sternocleidomastoid and forearm) of 14 healthy volunteers to highlight possible differences in microvascular hemodynamic oscillations. We observed larger PSDs for blood flow compared to hemoglobin concentration, in particular in case of distal muscles (i.e., thenar eminence and plantar fascia). Finally, we compared the PSDs measured on the thenar eminence of healthy subjects with the ones measured on a septic patient in the intensive care unit: lower power in the endothelial-dependent frequency band, and larger power in the myogenic ones were observed in the septic patient, in accordance with previous works based on laser doppler flowmetry.

Ultrasound evaluation of endothelial dysfunction in immunoglobulin-resistant children with acute Kawasaki disease

INTRODUCTION

Given the evidence that brachial artery flow-mediated dilation (FMD) is declined in children later after the onset of Kawasaki disease (KD), we hypothesized that indicators that detect the situation of the endothelium are useful parameters that can accurately reflect subclinical dysfunction in resistant patients and assist in differentiating patients with KD at a higher risk of IVIG resistance, which may be valuable in better understanding how to protect patients from endothelial and thrombotic complications.

METHODS

Fifty IVIG-resistant KD children, 120 IVIG-responsive KD children, 35 febrile children with acute upper respiratory infection, and 50 healthy controls were recruited, and indicators reflecting endothelial inflammation, including flow-mediated dilation (FMD), were measured. Receiver operating characteristic (ROC) curve analysis was utilized to determine the threshold values of these indicators of IVIG resistance. Multiple logistic regression analysis was performed to determine whether FMD was an independent predictor of IVIG-resistant patients.

RESULTS

In comparison with the lab data, PCT, Na + , and FMD exhibited AUCs of 0.727, 0.653, and 0.698 (P < 0.05), respectively, in predicting IVIG resistance in KD through ROC analysis. PCT > 1.69 ng/ml, Na +  < 133.2 mmol/l, and FMD < 5.79% were independent predictors of IVIG resistance in KD (OR 4.257, 3.516, 3.563, 95% CI 1.549 ~ 11.700, 1.277 ~ 9.680, 1.299 ~ 9.772, P < 0.05).

CONCLUSION

More severe endothelial dysfunction, especially lower FMD, was present in IVIG-resistant patients than in IVIG-responsive patients. It is a helpful diagnostic tool that provides supportive criteria to detect KD patients at a higher risk of IVIG resistance when FMD < 5.79% in children. Key Points • IVIG-resistant KD patients have more severe endothelial dysfunction than IVIG-sensitive patients. • FMD < 5.79% may indicate an increased risk of IVIG resistance in children with Kawasaki disease.

Endothelial Function Assessment by Flow-Mediated Dilation Method: A Valuable Tool in the Evaluation of the Cardiovascular System

Cardiovascular diseases (CVDs) in the course of atherosclerosis are one of the most critical public health problems in the world. Endothelial cells synthesize numerous biologically active substances involved in regulating the functions of the cardiovascular system. Endothelial dysfunction is an essential element in the pathogenesis of atherosclerosis. Thus, the assessment of endothelial function in people without overt CVD allows for a more accurate estimate of the risk of developing CVD and cardiovascular events. The assessment of endothelial function is primarily used in scientific research, and to a lesser extent in clinical practice. Among the tools for assessing endothelial function, we can distinguish biochemical and physical methods, while physical methods can be divided into invasive and non-invasive methods. Flow-mediated dilation (FMD) is based on the ultrasound assessment of changes in the diameter of the brachial artery as a result of increased blood flow. FMD is a non-invasive, safe, and repeatable test, but it must be performed by qualified and experienced medical staff. The purpose of this paper is to present the literature review results on the assessment of endothelial function using the FMD method, including its methodology, applications in clinical practice and research, limitations, and future perspectives.

Endothelial function and its determinants in children born after maternal bariatric surgery

BACKGROUND

Children born from mothers who underwent bariatric surgery were found to have an improved lipid profile and lower CRP levels compared to siblings born before surgery. We hypothesized that surgery before pregnancy might also influence endothelial function in the offspring.

METHODS

Blood sample analysis, blood pressure (BP) measurement, and peripheral arterial tonometry (PAT) were performed in 142 children (median age 10.5 years), either born from mothers who underwent bariatric surgery (BS) before pregnancy (n = 36) from mothers with overweight/obesity (OW/OB) (n = 71) or from normal weight (NW) mothers (n = 35), allowing the determination of the Reactive Hyperemia Index (RHI) in 111 children.

RESULTS

Children of the BS group had a higher diastolic blood pressure SDS and a lower RHI compared to the children of the OW/OB and NW group (1.32 versus 1.37 in OW/OB and 1.70 in NW; p = 0.004). After log transformation and correction for age, weight SDS, BMI SDS, body fat percentage, and diastolic BP SDS, RHI was comparable between the groups.

CONCLUSIONS

Children of mothers who underwent bariatric surgery before pregnancy do not have a disturbed endothelial function before puberty, when their increased diastolic BP and degree of adiposity is taken into account.

IMPACT

Children born after maternal bariatric surgery have a higher diastolic blood pressure without impaired endothelial function. To our knowledge, this is the first study that investigates the vascular function of children based on maternal characteristics during pregnancy. Adult offspring of mothers with obesity during pregnancy have an increased cardiovascular mortality. Since we cannot demonstrate a childhood-onset primary vascular dysfunction, this cardiovascular vulnerability might be more related to the hypertension and body adiposity. Thus, more emphasis should be made on the prevention of obesity and hypertension in the offspring at risk for development of obesity.

Metabolic and sympathovagal effects of bolus insulin glulisine versus basal insulin glargine therapy in people with type 2 diabetes: A randomized controlled study

AIMS/INTRODUCTION

This study compares the effects of two different insulin regimens - basal versus bolus insulin - on metabolic and cardiovascular autonomic function in Japanese participants with type 2 diabetes.

MATERIALS AND METHODS

Participants were randomly assigned to groups for therapy with insulin glulisine (IGlu) or insulin glargine (IGla). The primary efficacy end-point was glycemic variability, including M-values, mean of glucose levels, and a blood glucose profile of seven time points before and after the intervention. The secondary end-points included pleiotropic effects, including endothelial and cardiac autonomic nerve functions.

RESULTS

Blood glucose levels at all time points significantly decreased in both groups. Post-lunch, post-dinner, and bedtime blood glucose levels were significantly lower in the IGlu group than in the IGla group. Nadir fasting blood glucose levels at the end-point were significantly lower in the IGla group than in the IGlu group. The M-value and mean blood glucose levels were significantly decreased from baseline in both groups, although the former was significantly lower in the IGlu group than in the IGla group. IGla, but not IGlu, was found to elevate 24-h parasympathetic tone, especially during night-time, and it decreased 24-h sympathetic nerve activity, especially at dawn.

CONCLUSIONS

Both IGlu and IGla regimens reduced glucose variability, with IGlu bringing a greater reduction in M-value. IGla, but not IGlu, increased parasympathetic tone during night-time and decreased sympathetic nerve activity at dawn. These findings shed light on the previously unrecognized role of night-time basal insulin supplementation on sympathovagal activity in type 2 diabetes patients.

Feasibility and Tolerance of Fingertip Peripheral Arterial Tonometry Measurements in School-Aged Children

Background: Assessment of the endothelial function of the microvasculature by peripheral arterial tonometry (PAT) has gained increasing popularity in pediatrics. Discomfort or experienced pain during fingertip PAT has only been studied in adolescents and adults. Methods: In 142 children (aged 4-11 years old), a fingertip PAT with a commercial device (EndoPAT 2000®) as well as a caliper and ultrasound examination of peripheral skinfolds were performed as part of a cross-sectional cohort study. In 110 children, Faces Pain Scale (FPS-R) data were collected after PAT and skinfold measurements by caliper and ultrasound. Results: In 111 out of the 142 PAT measurements (78.2%), a reactive hyperemia index (RHI) could be obtained. The most frequent error messages by the software was a "too noisy" and/or a "poor quality" signal. The success rate was higher in children aged older than 6 years (83.1 vs. 44.4%; p < 0.001). Median (range) FPS-R after PAT was 0 (range 0-6) but was significantly higher than the median pain experienced after caliper measurements of peripheral skinfolds (p < 0.001). No pain was experienced by 59 of the 110 children (54.1%). Conclusion: PAT testing is feasible in the great majority of school-aged children, and the procedure is well-tolerated.

Endothelial function improvement in patients with familial hypercholesterolemia receiving PCSK-9 inhibitors on top of maximally tolerated lipid lowering therapy

BACKGROUND

Treatment with protein convertase subtilisin kexin type 9 inhibitors (PCSK-9i) reduced cholesterol levels and cardiovascular events in patients with hypercholesterolemia. We assessed changes in lipid profile, oxidation markers and endothelial function in patients with familial hypercholesterolemia (FH) after a 12-week treatment with a PCSK-9i.

METHODS

Patients with FH starting a treatment with PCSK-9i were included. Total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), lipoprotein(a) (Lp(a)), small dense LDL (assessed by LDL score), 11-dehydro-thromboxane (11-TXB2), 8-isoprostaglandin-2alpha (8-iso-PGF2α), flow-mediated dilation (FMD) and reactive hyperaemia index (RHI) were evaluated before starting PCSK-9i treatment and after a 12-week treatment.

RESULTS

Twenty-five subjects were enrolled (52% males, mean age 51.5 years). At the 12-week assessment, we observed a 38% median reduction in TC, 52% in LDL-C, 7% in Lp(a) and 46% in LDL score. In parallel, 11-TXB2 and 8-iso-PGF2α showed a reduction of 18% and 17%, respectively. FMD changed from 4.78% ± 2.27 at baseline to 10.6% ± 5.89 at 12 weeks (p < 0.001), with RHI changing from 2.37 ± 1.23 to 3.76 ± 1.36 (p < 0.001). A multivariate analysis showed that, after adjusting for potential confounders, change in LDL score was an independent predictor of changes in FMD (β = -0.846, p = 0.015) and in 8-iso-PGF2α (β = 0.778, p = 0.012).

CONCLUSIONS

Small dense LDL reduction (assessed by LDL score) is related to changes in oxidation markers and endothelial function in patients with FH treated with PCSK-9i.

Endothelial dysfunction in nonalcoholic steatohepatitis with low cardiac disease risk

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide. We prospectively evaluated endothelial function by assessing flow-mediated dilatation (FMD) of the brachial artery in patients with biopsy-proven NAFLD. This prospective study included 139 patients (50 healthy controls, 47 patients with steatosis and 42 patients with steatohepatitis), all of whom were nondiabetic. Patients with long-standing or uncontrolled hypertension, smokers, and morbidly obese patients were excluded. The medians (ranges) for vascular FMD in the steatohepatitis, steatosis, and control groups were 6% (0–37.5%), 10.8% (0–40%) and 13.6% (0–50%), respectively. The control group had a higher average FMD than the NAFLD group (15.13% vs 10.46%), and statistical significance was reached when the control and steatohepatitis groups were compared (13.6% vs 6%, p = 0.027). Average alanine aminotransferase was significantly higher in the steatohepatitis group than in the steatosis and control groups (54 (U/L) vs 31 (U/L), p = 0.008). Cholesterol levels were similar between all groups. In the multivariate analysis, FMD (OR = 0.85, p = 0.035) and high triglycerides (OR = 76.4, p = 0.009) were significant predictors of steatohepatitis. In the absence of major cardiac risk factors, we demonstrated better endothelial function in healthy controls, evidenced by a higher FMD of the brachial artery than that of patients with steatohepatitis.

Direct-acting antivirals improve endothelial function in patients with chronic hepatitis: a prospective cohort study

Hepatitis C virus (HCV) infection is associated with increased cardiovascular risk. We evaluated effects of direct-acting antiviral agents (DAAs) on flow-mediated dilation (FMD), a recognized marker of cardiovascular risk. We evaluated FMD and post-ischemic hyperemia (PIH) in consecutive HCV out-patients before starting DAAs, at the end of treatment (T_eot) and 12 weeks thereafter. In 22 HCV subjects (age 64.0 years), baseline FMD was 4.52% ± 1.90 and PIH of 5814.4 (IQR 3786.9-7861.9). At (T_eot), all patients showed undetectable levels of HCV-RNA and FMD changed from 4.52% ± 1.90 to 9.39% ± 4.06 (p < 0.001), with a direct correlation between changes in FMD and baseline HCV-RNA levels (r = 0.494, p = 0.020). In parallel, PIH increased from 5814.4 (IQR 3786.9-7861.9) to 7277.6 (IQR 4579.8-10388.8) (p = 0.019). Twelve weeks after T_eot, all patients had persistently negative HCV-RNA, FMD was 10.9% ± 4.65 and PIH was 10930.3 (IQR 6254.6-18248.2) suggesting a further significant improvement in these parameters. Results remained significant regardless of the presence of cardiovascular risk factors, whereas FMD changes were not statistically significant in subjects with cirrhosis. A persistent and significant improvement in endothelial function is observed in HCV patients obtaining viral eradication with DAAs treatment. This might suggest a beneficial effect of DAAs treatment on cardiovascular risk profile of HCV patients.

Physiological Association between Limb Ballistocardiogram and Arterial Blood Pressure Waveforms: A Mathematical Model-Based Analysis

By virtue of its direct association with the cardiovascular (CV) functions and compatibility to unobtrusive measurement during daily activities, the limb ballistocardiogram (BCG) is receiving an increasing interest as a viable means for ultra-convenient CV health and disease monitoring. However, limited insights on its physical implications have hampered disciplined interpretation of the BCG and systematic development of the BCG-based approaches for CV health monitoring. In this study, a mathematical model that can predict the limb BCG in responses to the arterial blood pressure (BP) waves in the aorta was developed and experimentally validated. The validated mathematical model suggests that (i) the limb BCG waveform reveals the timings and amplitudes associated with the aortic BP waves; (ii) mechanical filtering exerted by the musculoskeletal properties of the body can obscure the manifestation of the arterial BP waves in the limb BCG; and (iii) the limb BCG exhibits meaningful morphological changes in response to the alterations in the CV risk predictors. The physical insights garnered by the analysis of the mathematical model may open up new opportunities toward next generation of the BCG-based CV healthcare techniques embedded with transparency, interpretability, and robustness against the external variability.

Continuous Simultaneous Recording of Brachial Artery Distension and Wall Shear Rate: A New Boost for Flow-Mediated Vasodilation

Vascular ultrasound has been extensively applied in the clinical setting to noninvasively assess the endothelial function by means of the so-called brachial artery flow mediated dilation (FMD). Despite the usefulness in large-scale epidemiological studies, this approach has revealed some pitfalls for assessing vascular physiology and health in individual subjects. Mainly, a reliable FMD examination should be based on the simultaneous and reliable measurement of both the stimulus, i.e., the wall shear rate (WSR), and the response, i.e., the diameter change. However, multiple technical, practical, and methodological challenges must be faced to meet this goal. In this work, we present the technical developments needed to implement a system to enable the extensive and reliable clinical ultrasound FMD examination. It integrates both a hardware part, i.e., an upgraded version of the ultrasound advanced open platform (ULA-OP), and a software part, i.e., a signal processing and data analysis platform. The system was applied for a two-center pilot clinical study on 35 young and healthy volunteers. Therefore, we present here the results of a statistical analysis on magnitude, time-course, and kinetic parameters of WSR and diameter trends that allowed us to accurately explore the vasodilatory response to the dynamic WSR changes. Our observations demonstrate that a direct and accurate estimation of WSR stimulus by multigate spectral Doppler allows understanding brachial artery vasodilatory response to reactive hyperemia. Drawing inferences on WSR stimulus from the diameter response along with an inaccurate estimation of WSR may cause further uncertainties for the accurate interpretation of the FMD response.

Decreased endothelial function and increased subclinical heart failure in women several years after pre-eclampsia

OBJECTIVES

Pre-eclampsia (PE) is associated with both postpartum endothelial dysfunction and asymptomatic structural heart alterations consistent with heart failure Stage B (HF-B). In this study, we assessed the relationship between endothelial function, measured by flow-mediated dilation (FMD), and HF-B in women with a history of PE.

METHODS

This was an observational study in which 67 formerly pre-eclamptic women (≥ 4 years postpartum) and 37 healthy parous controls were assessed ultrasonographically for cardiac function and geometry, as well as for endothelial function by means of brachial artery FMD. HF-B was diagnosed as left ventricular hypertrophy (left ventricular mass index (LVMi) > 95 g/m² ), concentric remodeling (relative wall thickness > 0.42 and LVMi ≤ 95 g/m² ), mild systolic dysfunction (left ventricular ejection fraction > 40% and < 55%) or asymptomatic valvular disease. Cardiovascular and metabolic syndrome variables were compared between women with history of PE and controls, as well as between those in the formerly pre-eclamptic group who had HF Stage A, HF-B or no HF. Logistic regression analysis was performed to assess the associations of FMD with PE, metabolic syndrome risk factors and obstetric parameters.

RESULTS

The prevalence of HF-B amongst formerly pre-eclamptic women was three-fold higher than that observed for controls (25% vs 8%, P < 0.05), while FMD was lower in formerly pre-eclamptic women compared with controls (6.12% vs 8.22%, P < 0.01); history of PE remained associated independently with lower FMD after adjusting for metabolic syndrome risk factors and obstetric parameters (β, -1.88; 95% CI, -3.59 to -0.18). However, HF-B did not relate to low FMD in formerly pre-eclamptic women.

CONCLUSIONS

Years after pregnancy, formerly pre- eclamptic women have lower FMD and have HF-B more often compared with healthy parous controls. Nonetheless, HF-B was not related to reduced FMD. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

The effect of aspirin on circulating netrin-1 levels in humans is dependent on the inflammatory status of the vascular endothelium

In atherosclerotic animal models, the cyclo-oxygenase (COX)-inhibitor aspirin counteracts downregulation of endothelial-derived netrin-1, thus reducing arterial inflammation. We here explored the effect of aspirin on netrin-1 in healthy subjects undergoing influenza immunisation, which is an established experimental model of inflammation-related endothelial dysfunction.

Our data showed that netrin-1 undergoes reduction (-29.25% from baseline; p=0.0017) in the presence of endothelial activation (VCAM-1 rose by 9.98% 2-days post-vaccination; p=0.0022). Aspirin counteracted vaccine-induced endothelial activation and reduction of netrin-1 in a dose-dependent manner (-3.06% and -17.03% from baseline at a dose of 300mg and 75mg respectively; p=0.0465 and p>0.05 vs untreated). Clopidogrel, which was used as a comparator due to its similar anti-platelet activity, also reduced endothelial activation but, unlike aspirin, enhanced netrin-1 levels (+20.96% from baseline; p=0.0033 vs untreated). A correlation analysis incorporating cytokines, hs-CRP, VCAM-1, TXB₂ and PGE₂, showed that changes in netrin-1 were directly related to PGE₂ variations only (r=0.6103; p=0.0002). In a separate population of 40 healthy unimmunised volunteers, 28-day treatment with aspirin 300mg reduced netrin-1 (-18.76% from baseline; p=0.0012) without affecting endothelial markers or hs-CRP; as expected, aspirin suppressed TXB₂ and PGE₂. Netrin-1 and PGE₂ levels were directly related (r=0.358; p=0.0015), but other parameters including TXB₂, hs-CRP and endothelial markers, were not.

In conclusion, aspirin counteracts downregulation of netrin-1 following endothelial dysfunction due to its anti-inflammatory effect on the activated endothelium. However, inhibition of COX-dependent prostanoids negatively modulates netrin-1 synthesis in healthy subjects, and this could give rise to aspirin-dependent reduction in netrin-1 under steady state conditions.

Endothelial Function in Children and Adolescents Is Mainly Influenced by Age, Sex and Physical Activity - An Analysis of Reactive Hyperemic Peripheral Artery Tonometry

BACKGROUND

As adolescents rarely experience cardiovascular events, surrogate markers of atherosclerosis are useful to justify and monitor effects of primary prevention and therapy of risk factors. Endothelial function assessed by reactive hyperemic peripheral arterial tonometry (RH-PAT) resulting in a reactive hyperemic index (RHI) is a noninvasive method with limited data for use in children and adolescents.Methods and Results:We performed a total of 931 RHI measurements in 445 high-school students, aged 10-17 years, over a time period of 5 years. Students were randomized by class to 60 min physical exercise (PE) at school daily (intervention group), or 2 units of 45-min PE weekly (control group). To characterize the factors influencing the RHI, anthropometry, cardiopulmonary exercise testing, blood cholesterol and quality of life were assessed and used to build mixed linear models. Main influential factors were age, with an increase of RHI from 1.53±0.42 in the youngest to 1.96±0.59 in the oldest students, sex, with higher values in girls, and physical activity. This increase adjusted by age and sex was estimated as 0.11 [0.08, 0.14] per year. RHI was higher in the intervention group by 0.09 [-0.05, 0.23] in comparison with the control group.

CONCLUSIONS

If RH-PAT is used in research or as a clinical tool in adolescents, the shown age- and sex-dependence of RHI have to be taken in account.

Increased fibrinogen responses to psychophysiological stress predict future endothelial dysfunction implications for cardiovascular disease?

Stress influences the risk of cardiovascular disease. Acute mental stress can induce both low-grade inflammation and endothelial dysfunction. The relationship between inflammatory responses to stress and future endothelial function is unexplored. Knowledge on the impact of other cardiovascular risk factors, such as dyslipidaemia, on such relationships is also limited We investigated the relationship between inflammatory responses to an acute mental stress challenge and endothelial function plus the influence of dyslipidaemia on the associations. Interleukin-6 (IL-6), tumor necrosis factor α (TNFα) and fibrinogen were assessed at baseline, immediately following standardized behavioural tasks and 45 min post-task in 158 participants. Blood pressure and heart rate responses were measured. Flow-mediated dilatation (FMD) was measured 3years later. Fibrinogen and IL-6 increased post-stress (p⩽0.001 & 0.003) but TNFα was unchanged (p=0.09). An independent negative association between FMD and change in fibrinogen at 45 min (β=-0.047 p=0.016) remained after multiple adjustment (baseline fibrinogen, baseline diameter, reactive hyperaemia, age, gender and other cardiovascular risk factors). There was no association between FMD and change in IL-6 or TNFα. There were no differences in the responses to stress between those with and without dyslipidaemia. However, there was an interaction between the presence of dyslipidaemia and immediate change in fibrinogen with stress which was associated with FMD. Those participants with dyslipidaemia who had a greater change in fibrinogen had lower FMD. We conclude that elevated fibrinogen responses to stress are associated with future endothelial dysfunction which may reflect increased cardiovascular risk.

Accelerated resolution of inflammation underlies sex differences in inflammatory responses in humans

BACKGROUND

Cardiovascular disease occurs at lower incidence in premenopausal females compared with age-matched males. This variation may be linked to sex differences in inflammation. We prospectively investigated whether inflammation and components of the inflammatory response are altered in females compared with males.

METHODS

We performed 2 clinical studies in healthy volunteers. In 12 men and 12 women, we assessed systemic inflammatory markers and vascular function using brachial artery flow-mediated dilation (FMD). In a further 8 volunteers of each sex, we assessed FMD response to glyceryl trinitrate (GTN) at baseline and at 8 hours and 32 hours after typhoid vaccine. In a separate study in 16 men and 16 women, we measured inflammatory exudate mediators and cellular recruitment in cantharidin-induced skin blisters at 24 and 72 hours.

RESULTS

Typhoid vaccine induced mild systemic inflammation at 8 hours, reflected by increased white cell count in both sexes. Although neutrophil numbers at baseline and 8 hours were greater in females, the neutrophils were less activated. Systemic inflammation caused a decrease in FMD in males, but an increase in females, at 8 hours. In contrast, GTN response was not altered in either sex after vaccine. At 24 hours, cantharidin formed blisters of similar volume in both sexes; however, at 72 hours, blisters had only resolved in females. Monocyte and leukocyte counts were reduced, and the activation state of all major leukocytes was lower, in blisters of females. This was associated with enhanced levels of the resolving lipids, particularly D-resolvin.

CONCLUSIONS

Our findings suggest that female sex protects against systemic inflammation-induced endothelial dysfunction. This effect is likely due to accelerated resolution of inflammation compared with males, specifically via neutrophils, mediated by an elevation of the D-resolvin pathway.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01582321 and NRES: City Road and Hampstead Ethics Committee: 11/LO/2038.

FUNDING

The authors were funded by multiple sources, including the National Institute for Health Research, the British Heart Foundation, and the European Research Council.

Randomized clinical trial on the efficacy of hesperidin 2S on validated cardiovascular biomarkers in healthy overweight individuals

BACKGROUND

Endothelial dysfunction (ED) is involved in the development of atherosclerosis. Hesperidin, a citrus flavonoid with antioxidant and other biological properties, potentially exerts beneficial effects on endothelial function (EF).

OBJECTIVE

We investigated the effect of hesperidin 2S supplementation on EF in overweight individuals.

DESIGN

This was a randomized, double-blind, placebo-controlled study in which 68 individuals were randomly assigned to receive hesperidin 2S (450 mg/d) or a placebo for 6 wk. At baseline and after 6 wk of intervention, flow-mediated dilation (FMD), soluble vascular adhesion molecule-1 (sVCAM-1), soluble intracellular adhesion molecule-1 (sICAM-1), soluble P-selectin (sP-selectin), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were assessed. Acute, reversible ED was induced by intake of a high-fat meal (HFM). A second FMD scan was performed 2 h postprandially, and adhesion molecules were assessed 2 and 4 h postprandially. An additional exploratory analysis was performed in subjects with baseline FMD ≥3%.

RESULTS

No significant change in fasting or postprandial FMD was observed after 6 wk of hesperidin intake compared with placebo intake. However, there was a trend for a reduction of sVCAM-1, sICAM-1, sP-selectin, SBP, and DBP after 6 wk of hesperidin treatment. In the FMD ≥3% group, hesperidin protected individuals from postprandial ED (P = 0.050) and significantly downregulated sVCAM-1 and sICAM-1 (all P ≤ 0.030). The results reported in the current article were not adjusted for multiplicity.

CONCLUSIONS

Six weeks of consumption of hesperidin 2S did not improve basal or postprandial FMD in our total study population. There was a tendency toward a reduction of adhesion molecules and a decrease in SBP and DBP. Further exploratory analyses revealed that, in subjects with baseline FMD ≥3%, hesperidin 2S improved ED after an HFM and reduced adhesion molecules. These results indicate the cardiovascular health benefits of hesperidin 2S in overweight and obese individuals with a relatively healthy endothelium. This trial was registered at clinicaltrials.gov as NCT02228291.

Associations between measures of vascular structure and function and systemic circulating blood markers in humans

Examination of relationships between systemic markers and functional measures of arterial structure and function may assist in determining alternative indices of vascular regulation and designing and evaluating interventions to improve arterial structure and function. Twenty young healthy individuals, 20 older healthy men, and 26 individuals with coronary artery disease (CAD), comprising a spectrum of vascular health, participated. Systemic markers of vascular structure and function included: pro‐collagen type I C‐peptide (PIP) – marker of collagen synthesis, C‐telopeptide of type I collagen (CTX) – marker of collagen degradation, endothelin‐1 (ET‐1) ‐ vasoconstrictor, and interleukin‐6 (IL‐6) – inflammatory marker. Functional measures of arterial structure and function included carotid artery distensibility and brachial artery flow‐mediated dilation (FMD). Moderate positive relationships were observed between carotid distensibility and CTX and PIP (r = 0.57, P < 0.0001 and r = 0.47, P < 0.0001). A negative correlation exists between ET‐1 and FMD (r = −0.44, P = 0.0004); however, no relationship was observed between IL‐6 and FMD (P = 0.25). Over a broad range of vascular health, relationships were observed between markers of type I collagen turnover and arterial stiffness and between a marker of vasoconstriction and endothelial function. These results indicate that regulatory links, between the indices examined, exist. Therefore, monitoring systemic markers rather than functional vascular measures, may provide sufficient information about vascular health and should be considered in the design and evaluation of vascular interventions.

Inflammatory Cytokines, Endothelial Function, and Chronic Allograft Vasculopathy in Children: An Investigation of the Donor and Recipient Vasculature After Heart Transplantation

Chronic allograft vasculopathy (CAV) limits the lifespan of pediatric heart transplant recipients. We investigated blood markers of inflammation, endothelial dysfunction, and damage to both the native and transplanted vasculature in children after heart transplantation. Serum samples were taken from pediatric heart transplant recipients for markers of inflammation and endothelial activation. The systemic vasculature was investigated using brachial artery flow-mediated dilatation and carotid artery intima-medial hyperplasia. CAV was investigated using intravascular ultrasound. Mean intima-media thickness (mIMT) > 0.5 mm was used to define significant CAV. Forty-eight children (25 male) aged 8-18 years were enrolled in the study. Patients were a median (interquartile range) 4.1 (2.2-8.7) years after transplant. Patients had increased levels of circulating IL6 (3.86 [2.84-4.95] vs. 1.66 [1.22-2.63] p < 0.0001), vascular cell adhesion molecule 1 (539 [451-621] vs. 402 [342-487] p < 0.001), intracellular adhesion molecule 1 305 (247-346) vs. 256 (224-294) p = 0.002 and thrombomodulin (7.1 [5.5-8.1] vs. 3.57 [3.03-4.71] p < 0.0001) and decreased levels of tumor necrosis factor-α, E selectin, and P selectin, compared with controls. The systemic vasculature was unaffected. Patients with severe CAV had raised serum von Willebrand factor and decreased serum thrombomodulin. Posttransplant thrombomodulin levels are elevated after transplant but significantly lower in those with mIMT > 0.5 mm. This suggests that subclinical inflammation is present and that natural anticoagulant/thrombomodulin activity is important after transplant.

Anti-platelet drugs attenuate the expansion of circulating CD14highCD16+ monocytes under pro-inflammatory conditions

Aims

Levels of circulating CD14^highCD16⁺ monocytes increase in atherosclerotic patients and are predictive of future cardiovascular events. Platelet activation has been identified as a crucial determinant in the acquisition of a CD16⁺ phenotype by classical CD14^highCD16⁻ cells. We tested the hypothesis that anti-platelet drugs modulate the phenotype of circulating monocytes.

Methods and results

Sixty healthy subjects undergoing influenza immunization were randomly assigned to either no treatment or anti-platelet therapy, namely aspirin 300 mg or 75 mg daily, or clopidogrel (300 mg loading dose followed by 75 mg), for 48 h post-immunization (n = 15/group). Monocyte subsets, high-sensitivity C-reactive protein, pro-inflammatory cytokines, and P-selectin were measured at baseline and post-immunization. The CD14^highCD16⁺ monocyte cell count rose by 67.3% [interquartile range (IQR): 35.7/169.2; P = 0.0002 vs. baseline] in untreated participants. All anti-platelet regimes counteracted expansion of this monocytic subpopulation. Although no statistical differences were noted among the three treatments, aspirin 300 mg was the most efficacious compared with the untreated group (−12.5% change from baseline; IQR: −28.7/18.31; P = 0.001 vs. untreated). Similarly, the rise in P-selectin (17%; IQR: −5.0/39.7; P = 0.03 vs. baseline) observed in untreated participants was abolished by all treatments, with aspirin 300 mg exerting the strongest effect (−30.7%; IQR: −58.4/−0.03; P = 0.007 vs. untreated). Changes in P-selectin levels directly correlated with changes in CD14^highCD16⁺ cell count (r = 0.5; P = 0.0002). There was a similar increase among groups in high-sensitivity C-reactive protein (P < 0.03 vs. baseline levels).

Conclusions

Anti-platelet drugs exert an immunomodulatory action by counteracting CD14^highCD16⁺ monocyte increase under pro-inflammatory conditions, with this effect being dependent on the amplitude of P-selectin reduction.

Adherence to guidelines strongly improves reproducibility of brachial artery flow-mediated dilation

BACKGROUND

Brachial artery FMD is widely used as a non-invasive measure of endothelial function. Adherence to expert guidelines is believed to be of vital importance to obtain reproducible measurements. We conducted a systematic review of studies reporting on the reproducibility of the FMD in order to determine the relation between adherence to current expert guidelines for FMD measurement and its reproducibility.

METHODS

Medline-database was searched through July 2015 and 458 records were screened for FMD reproducibility studies reporting the mean difference and variance of repeated FMD measurements. An adherence score was assigned to each of the included studies based on reported adherence to published guidelines on the assessment of brachial artery FMD. A Typical Error Estimate (TEE) of the FMD was calculated for each included study. The relation between the FMD TEE and the adherence score was investigated by means of Pearson correlation coefficients and multiple linear regression analysis.

RESULTS

Twenty-seven studies involving 48 study groups and 1537 subjects were included in the analyses. The adherence score ranged from 2.4 to 9.2 (out of a maximum of 10) and was strongly and inversely correlated with FMD TEE (adjusted R(2) = 0.36, P < 0.01). Use of automated edge-detection software, continuous diameter measurement, true peak diameter for %FMD calculation, a stereostatic probe holder, and higher age emerged as factors associated with a lower FMD TEE.

CONCLUSIONS

These data demonstrate that adherence to current expert consensus guidelines and applying contemporary techniques for measuring brachial artery FMD decreases its measurement error.

Casein Compared with Whey Proteins Affects the Organization of Dietary Fat during Digestion and Attenuates the Postprandial Triglyceride Response to a Mixed High-Fat Meal in Healthy, Overweight Men

BACKGROUND

Postprandial lipemia is a risk factor for cardiovascular disease. The potential impacts of the type/nature of dietary protein on postprandial lipemia and associated dysregulations have been insufficiently investigated.

OBJECTIVE

We investigated the postprandial effect of including in a high-fat meal some milk protein fractions that markedly differ in their physicochemical properties and composition [either casein (CAS), whey protein (WHE), or α-lactalbumin-enriched whey protein (LAC)].

METHODS

The protein fractions were incorporated as 15% energy in a high-fat meal in a 3-period, crossover postprandial study of 10 healthy overweight men with an elevated waist circumference (>94 cm). We measured postprandial changes in plasma lipids, amino acids, glucose, and oxidative stress markers, vascular function (using pulse contour analysis), and low-grade inflammation (using plasma markers). We also characterized in vitro the meal structures, including the size of the fat globule, and possible changes during digestion.

RESULTS

The type of protein did not affect postprandial plasma glucose, amino acids, insulin, or nonesterified fatty acids, but, compared with WHE and LAC, which did not differ, CAS markedly reduced postprandial triglycerides (TGs), achieving a 22 ± 10% reduction in the 6-h area under the curve (P < 0.05). Similar trends were shown for plasma chylomicrons [apolipoprotein (apo)B-48; P < 0.05]. However, there were no significant differences between the meals regarding postprandial oxidative stress (plasma hydroperoxides and malondialdehyde), endothelial dysfunction (salbutamol-induced changes in pulse contour analysis), or low-grade inflammation. In vitro studies showed that when the pH of the meal decreased to stomach pH values, the reduction in the solubility of casein resulted in a phase separation between fat and protein, whereas the proteins in the other meals remained suspended with fat globules.

CONCLUSION

In healthy overweight men, casein has specific physical interactions with fat that affect postprandial TGs, leading to the formation of fewer chylomicrons or an increase in chylomicron clearance. This trial was registered at clinicaltrials.gov as NCT00931151.

Brachial Low-Flow-Mediated Constriction is Associated with Delayed Brachial Flow-Mediated Dilation

AIM

Flow-mediated vasodilation (FMD) of the brachial artery measures the ability of the artery to dilate after a forearm ischemia lasting for 5 min. During ischemia, and therefore in conditions of low flow, constriction of the brachial artery (L-FMC) has sometimes been reported. The meaning of L-FMC is still unclear. The aims of our study were to establish the prevalence of subjects with L-FMC, to determine whether the magnitude of L-FMC correlates with magnitude of FMD, and to determine whether L-FMC can be used to predict FMD timing.

METHODS

A total of 179 outpatients were studied, and the brachial artery diameter was measured every minute during the 5 min forearm ischemia. Subjects who had at least one measurement showing a constriction of ＞ 1% during ischemia were defined as constrictors. FMD was evaluated at 50 s, 2 min, and 3 min after cuff release. On the basis of time, the subjects in whom maximal dilation had occurred were divided into Early, Late, or No dilators.

RESULTS

The brachial artery diameter of 70 subjects (39%) constricted during ischemia. Higher the constriction during ischemia, lower was the dilation after ischemia. Constrictors were more likely to have Late (OR 2.6; ICs 95% 1.19-5.81, p=0.02) or No dilation (OR 4.8; ICs 95% 1.90-12-16, p=0.02) compared with no constrictors.

CONCLUSIONS

The present study reveals that almost 40% of the subjects had brachial artery L-FMC and a more pronounced constriction during ischemia correlated with a lower dilation after ischemia. Finally, the prevalence of subjects showing L-FMC was significantly higher among subjects with delayed or no vasodilation, suggesting that L-FMC may be a marker of endothelial dysfunction.

Peripheral microcirculatory hemodynamic changes in patients with myocardial ischemia

BACKGROUND

Patients with coronary heart disease demonstrate changes in skin microcirculation and a decrease in cutaneous blood mass.

OBJECTIVE

The goal of this study was to assess the feasibility of diagnosing myocardial ischemia based on peripheral microcirculatory variables.

METHODS

The skin microcirculatory measurements were monitored using an LPT system comprising a Laser Doppler Flowmeter (LDF), a photoplethysmograph (PPG) and a transcutaneous oxygen tension device (tc-PO2). Concurrently, heart rate and blood pressure were monitored. Measurements were performed before and after exercise stress test. Subjects were divided into ischemic (20) and nonischemic (27) patients based on myocardial perfusion imaging (MPI).

RESULTS

The results indicate differences in LPT variables between ischemic and nonischemic patients following exercise, while no differences in the central variable values were observed between the two groups.

CONCLUSIONS

Peripheral microcirculatory variables may be useful for non-invasive assessment of myocardial ischemia. The system has clinical potential for sensitive and noninvasive monitoring of vital variables during medical procedures in clinics, as well as in home care for patients who suffer from ischemic cardiac diseases.

Microvascular dysfunction in schizophrenia: a case-control study

Background:

Schizophrenia is a mental illness associated with cardiovascular disease at a younger age than in the general population. Endothelial dysfunction has predictive value for future cardiovascular events; however, the impact of a diagnosis of schizophrenia on this marker is unknown.

Aims:

We tested the hypothesis that subjects with schizophrenia have impaired endothelial function.

Methods:

A total of 102 subjects (34.5±7.5 years) participated in this study. This sample consisted of 51 subjects with a diagnosis of schizophrenia and 51 healthy subjects, who were matched for age (P=0.442), sex (P>0.999), and smoking status (P=0.842). Peripheral artery microvascular and conduit vessel endothelial function was measured using hyperemic velocity time integral (VTI), pulse arterial tonometry (PAT), and flow-mediated dilation (FMD).

Results:

Significantly lower values of VTI were noted in subjects with schizophrenia (104.9±33.0 vs. 129.1±33.8 cm, P<0.001), whereas FMD (P=0.933) and PAT (P=0.862) did not differ between the two groups. A multivariable-linear-regression analysis, built on data from univariate and partial correlations, showed that only schizophrenia, sex, lipid-lowering medications, antihypertensive medications, and low-density lipoprotein (LDL)-cholesterol were predictive of attenuated VTI, whereas age, ethnicity, family history of cardiovascular disease, smoking status, systolic blood pressure, waist circumference, HDL-cholesterol, triglycerides, C-reactive protein, and homeostatic model assessment-insulin resistance (HOMA-IR), antidiabetic medications, antidepressant medications, mood stabilizers, benzodiazepines, and anticholinergic medications did not predict VTI in this model (adjusted R²=0.248).

Conclusions:

Our findings suggest that a diagnosis of schizophrenia is associated with impaired microvascular function as indicated by lower values of VTI, irrespective of many other clinical characteristics. It might be an early indicator of cardiovascular risk in schizophrenia, and might help to identify high-risk individuals.

Comprehensive assessment of vascular health in patients; towards endothelium-guided therapy

Endothelial function has diagnostic, prognostic and therapeutic significance. A number of non-invasive techniques were introduced for its assessment, including flow-mediated dilation (FMD), finger plethysmography (RH-PAT) and digital thermal monitoring (DTM). All these methods can be performed simultaneously. In addition, various methods for measuring arterial wall stiffness are available such as: pulse wave analysis (PWA), pulse wave velocity (PWV), pulse contour analysis (PCA) and carotid wall distensibility coefficient (DC). Finally, carotid intima-media thickness (cIMT) and ankle brachial index (ABI) are used as surrogate read-outs of atherosclerosis. Here, we briefly describe the advantages, limitations and interrelationships of various methods used for the assessment of endothelial function, arterial stiffness, and present the concept of an integrated evaluation of vascular health based on multiple methods. This strategy may be useful to stratify cardiovascular risk and represents a step towards multiparametric assessment of endothelium for effective endothelium-guided therapy in patients with cardiovascular diseases.

Effects of acute and chronic exercise in patients with essential hypertension: benefits and risks

The importance of regular physical activity in essential hypertension has been extensively investigated over the last decades and has emerged as a major modifiable factor contributing to optimal blood pressure control. Aerobic exercise exerts its beneficial effects on the cardiovascular system by promoting traditional cardiovascular risk factor regulation, as well as by favorably regulating sympathetic nervous system (SNS) activity, molecular effects, cardiac, and vascular function. Benefits of resistance exercise need further validation. On the other hand, acute exercise is now an established trigger of acute cardiac events. A number of possible pathophysiological links have been proposed, including SNS, vascular function, coagulation, fibrinolysis, and platelet function. In order to fully interpret this knowledge into clinical practice, we need to better understand the role of exercise intensity and duration in this pathophysiological cascade and in special populations. Further studies in hypertensive patients are also warranted in order to clarify the possibly favorable effect of antihypertensive treatment on exercise-induced effects.

Weight loss improves fasting flow-mediated vasodilation in adults: a meta-analysis of intervention studies

BACKGROUND

Obesity is associated with vascular endothelial dysfunction. Effects of weight loss on endothelial function are however not clear. Therefore, we performed a meta-analysis to quantify effects of weight loss on flow-mediated vasodilation (FMD) of the brachial artery, a measurement of endothelial function.

METHODS

Studies with experimental (RCTs) and quasi-experimental designs published before June 2014 were identified by a systematic search. Changes in FMD were defined as the difference between measurements before and after the study. For RCTs, changes were corrected for those in the no-weight loss control group. Summary estimates of weighted mean differences (WMDs) in FMD and 95% confidence intervals (CIs) were calculated using random-effect meta-analyses. The impact of subject characteristics, type of weight-loss treatment, and dietary composition on changes in FMD was also investigated.

RESULTS

Four RCTs involving 265 subjects were included. Weight loss increased FMD vs. control by 3.29% (95% CI: 0.98-5.59%; P = 0.005; mean weight loss: 8.6 kg). A total of 1517 subjects participated in 33 studies with 49 relevant study arms. It was estimated that each 10 kg decrease in body weight increased fasting FMD by 1.11% (95% CI: 0.47-1.76%; P = 0.001). Effects were more pronounced when participants had coexisting obesity-related morbidities. Also, effects may be larger when subjects received low-fat diets or weight-reduction regimens including exercise therapy or weight-loss medication.

CONCLUSION

Weight loss significantly improves fasting FMD in adults, which is a risk marker for cardiovascular disease. Effects may depend on subject characteristics, type of weight-loss treatment, and dietary composition.

Superficial femoral artery endothelial responses to a short-term altered shear rate intervention in healthy men

In animal and in-vitro models, increased oscillatory shear stress characterized by increased retrograde shear-rate (SR) is associated with acutely decreased endothelial cell function. While previous research suggests a possible detrimental role of elevated retrograde SR on endothelial-function in the brachial artery in humans, little research has been conducted examining arteries in the leg. Examinations of altered shear pattern in the superficial femoral artery (SFA) are important, as this vessel is both prone to atherosclerosis and leg exercise is a common form of activity in humans. Seven healthy men participated; bilateral endothelial-function was assessed via flow-mediated-dilation (FMD) before and after 30-minute unilateral inflations of a thigh blood pressure cuff to either 75 mmHg or 100 mmHg on two separate visits. Inflation of the cuff induced increases in maximum anterograde (p<0.05), maximum retrograde (p<0.01), and oscillatory shear index (OSI) (p<0.001) in the cuffed leg at both inflation pressures. At 100 mmHg the increases in SR were larger in the retrograde than the anterograde direction evidenced by a decrease in mean SR (p<0.01). There was an acute decrease in relative FMD in the cuffed leg alone following inflation to both pressures. These results indicate that in the SFA, altered SR profiles incorporating increased retrograde and OSI influence the attenuation in FMD after a 30-minute unilateral thigh-cuff inflation intervention. Novel information highlighting the importance of OSI calculations and assessments of flow profiles add to current body of knowledge regarding the influence of changes in SR patterns on FMD. Findings from the current study may provide additional insight when designing strategies to combat impaired vascular function in the lower extremity where blood vessels are more prone to atherosclerosis in comparison to the upper extremity.

Type 2 Diabetes: Endothelial dysfunction and Exercise

PURPOSE

Vascular endothelial dysfunction is an early marker of atherosclerosis characterized by decreased nitric oxide bioavailability in the vascular endothelium and smooth muscle cells. Recently, some animal models and in vitro trials demonstrated that excessive superoxide production from mitochondria within vascular endothelial cells played a role in the pathogenesis of atherosclerosis in type 2 diabetes. This review provides a systematic assessment of the effectiveness of exercise to identify effective approaches to recognize diabetes risk and prevent progression to heart disease.

METHODS

A systematic literature search was conducted to retrieve articles from 1979 to 2013 using the following databases: the MEDLINE, PubMed. Articles had to describe an intervention that physical activity and exercise to identify effective approaches to heart and vascular endothelium.

RESULTS

Currently, physical activity and exercise guidelines aimed to improve cardiovascular health in patients with type 2 diabetes are nonspecific. Benefit of aerobic exercise training on vascular endothelial function in type 2 diabetic patients is still controversial.

CONCLUSION

it is necessary to demonstrate the mechanism of endothelial dysfunction from live human tissues so that we can provide more specific exercise training regimens to enhance cardiovascular health in type 2 diabetic patients.

Vegan diet, subnormal vitamin B-12 status and cardiovascular health

Vegetarian diets have been associated with atherosclerosis protection, with healthier atherosclerosis risk profiles, as well as lower prevalence of, and mortality from, ischemic heart disease and stroke. However, there are few data concerning the possible cardiovascular effects of a vegan diet (with no meat, dairy or egg products). Vitamin B-12 deficiency is highly prevalent in vegetarians; this can be partially alleviated by taking dairy/egg products in lact-ovo-vegetarians. However, metabolic vitamin B-12 deficiency is highly prevalent in vegetarians in Australia, Germany, Italy and Austria, and in vegans (80%) in Hong Kong and India, where vegans rarely take vitamin B-12 fortified food or vitamin B-12 supplements. Similar deficiencies exist in northern Chinese rural communities consuming inadequate meat, egg or dairy products due to poverty or dietary habits. Vascular studies have demonstrated impaired arterial endothelial function and increased carotid intima-media thickness as atherosclerosis surrogates in such metabolic vitamin B-12 deficient populations, but not in lactovegetarians in China. Vitamin B-12 supplementation has a favourable impact on these vascular surrogates in Hong Kong vegans and in underprivileged communities in northern rural China. Regular monitoring of vitamin B-12 status is thus potentially beneficial for early detection and treatment of metabolic vitamin B-12 deficiency in vegans, and possibly for prevention of atherosclerosis-related diseases.

Delayed vasodilation is associated with cardiovascular risk

BACKGROUND

Flow-mediated dilation (FMD) of the brachial artery is widely used to assess cardiovascular risk. In recent years, much attention has been paid to the kinetics of vasodilation in an attempt to better characterize the endothelial function. Here, we investigated whether FMD magnitude and/or latency are most related to individual cardiovascular risk.

MATERIALS AND METHODS

Four hundred subjects were recruited. Individual risk prediction was estimated by Framingham cardiovascular risk score and CUORE project calculator. Subjects were divided into Early dilators (peak FMD at 50 s), Late dilators (peak FMD over 50 s) and No dilators.

RESULTS

Cardiovascular risk was highest in No dilators and significantly higher in Late than Early dilators despite comparable peak FMD. When divided according to peak FMD quintiles, Early and Late dilators showed decreased cardiovascular risk with increasing magnitude of vasodilation. However, subjects in the first three quintiles of Late dilators had a markedly higher risk score despite a peak vasodilation similar to that of Early dilators.

CONCLUSION

These results suggest that the magnitude of the FMD and its latency are both important for identifying patients at risk of cardiovascular disease. Subjects with a delayed though significant vasodilation associated with a blunted early response exhibit the highest cardiovascular risk.

Association of digital vascular function with cardiovascular risk factors: a population study

OBJECTIVES

Vasodilation of the peripheral arteries during reactive hyperaemia depends in part on release of nitric oxide from endothelial cells. Previous studies mainly employed a fingertip tonometric device to derive pulse wave amplitude (PWA) and PWA hyperaemic changes. An alternative approach is based on photoplethysmography (PPG). We sought to evaluate the correlates of digital PPG PWA hyperaemic responses as a measure of peripheral vascular function.

DESIGN

The Flemish Study on Environment, Genes and Health Outcomes (FLEMENGHO) is a population-based cohort study.

SETTING

Respondents were examined at one centre in northern Belgium.

PARTICIPANTS

For this analysis, our sample consisted of 311 former participants (53.5% women; mean age 52.6 years; 43.1% hypertensive), who were examined from January 2010 until March 2012 (response rate 85.1%).

PRIMARY OUTCOME MEASURES

Using a fingertip PPG device, we measured digital PWA at baseline and at 30 s intervals for 4 min during reactive hyperaemia induced by a 5 min forearm cuff occlusion. We performed stepwise regression to identify correlates of the hyperaemic response ratio for each 30 s interval after cuff deflation.

RESULTS

The maximal hyperaemic response was detected in the 30-60 s interval. The explained variance for the PPG PWA ratio ranged from 9.7% at 0-30 s interval to 22.5% at 60-90 s time interval. The hyperaemic response at each 30 s interval was significantly higher in women compared with men (p≤0.001). The PPG PWA changes at 0-90 s intervals decreased with current smoking (p≤0.0007) and at 0-240 s intervals decreased with higher body mass index (p≤0.035). These associations with sex, current smoking and body mass index were mutually independent.

CONCLUSIONS

Our study is the first to implement the new PPG technique to measure digital PWA hyperaemic changes in a general population. Hyperaemic response, as measured by PPG, is inversely associated with traditional cardiovascular risk factors such as male sex, smoking and obesity.

Endothelial function increases after a 16-week diet and exercise intervention in overweight and obese young women

Weight loss improves endothelial function in overweight individuals. The effects of weight loss through combined aerobic and resistance training and caloric restriction on in vivo vascular measures and blood markers associated with the regulation of endothelial function have not been comprehensively examined. Therefore, we investigated brachial artery endothelial function and potential regulatory blood markers in twenty overweight women (30.3 ± 2.0 years) who participated in 16 weeks of aerobic (5 d/wk) and resistance training (2 d/wk) (combined: ≥250 kcal/d) and caloric restriction (−500 kcal/d versus requirement). Resting brachial artery flow mediated dilation (FMD) and circulating endothelin-1 (ET-1) and interleukin-6 (IL-6) were assessed at baseline and following the intervention. Relative and absolute FMD increased (before: 4.0 ± 0.5% versus after: 6.9 ± 0.6%, P < 0.05, and before: 0.14 ± 0.02 mm versus after: 0.23 ± 0.02 mm, P < 0.05, resp.), while body mass decreased (before: 86.9 ± 2.4 kg versus after: 81.1 ± 2.4 kg, P < 0.05) following the intervention. There were no changes in either blood marker (IL-6: before: 1.5 ± 0.2 pg/mL versus after: 1.5 ± 0.1 pg/mL, P > 0.05, and ET-1: before: 0.55 ± 0.05 pg/mL versus after: 0.59 ± 0.09 pg/mL, P > 0.05). 16 weeks of combined aerobic/resistance training and diet-induced weight loss improved endothelial function in overweight and obese young women, but this increase was not associated with changes in blood markers of vasoconstriction or inflammation.

Effect of bariatric surgery on microvascular dysfunction associated to metabolic syndrome: a 12-month prospective study

OBJECTIVE

To prospectively evaluate the effect of weight loss after bariatric surgery on microvascular function in morbidly obese patients with and without metabolic syndrome (MetS).

METHODS

A cohort of morbidly obese patients with and without MetS was studied before surgery and after 12 months of surgery. Healthy lean controls were also examined. Microvascular function was assessed by postocclusive reactive hyperemia (PORH) at forearm skin evaluated by laser Doppler flowmetry (LDF). Cutaneous vascular conductance (CVC) was calculated from laser-Doppler skin blood flow and blood pressure. Regression analysis was performed to assess the contribution of different clinical, metabolic and biochemical parameters to microvascular function.

RESULTS

Before surgery, 62 obese patients, 39 with MetS and 23 without MetS, and 30 lean control subjects were analyzed. The absolute area under the hyperemic curve (AUC(H)) CVC of PORH was significantly decreased in obese patients compared with lean control subjects. One year after surgery, AUC(H) CVC significantly increased in patients free of MetS, including patients that had MetS before surgery. In contrast, AUC(H) CVC did not significantly change in patients in whom MetS persisted after surgery. Stepwise multivariate regression analysis showed that only changes in HDL cholesterol (HDL-C) and oxidized LDL (oxLDL) independently predicted improvement of AUC(H) after surgery. These two variables together accounted for 40.9% of the variability of change in AUC(H) CVC after surgery.

CONCLUSIONS

Bariatric surgery could significantly improve microvascular dysfunction in obese patients, but only in patients free of MetS after surgery. Improvement of microvascular dysfunction is strictly associated to postoperative increase in HDL-C levels and decrease in oxLDL levels.

The effects of dietary nitrate on blood pressure and endothelial function: a review of human intervention studies

Evidence has accumulated in recent years that suggests that nitrate from the diet, particularly vegetables, is capable of producing bioactive NO in the vasculature, following bioconversion to nitrite by oral bacteria. The aim of the present review was to consider the current body of evidence for potential beneficial effects of dietary nitrate on blood pressure and endothelial function, with emphasis on evidence from acute and chronic human intervention studies. The studies to date suggest that dietary nitrate acutely lowers blood pressure in healthy humans. An inverse relationship was seen between dose of nitrate consumed and corresponding systolic blood pressure reduction, with doses of nitrate as low as 3 mmol of nitrate reducing systolic blood pressure by 3 mmHg. Moreover, the current studies provide some promising evidence on the beneficial effects of dietary nitrate on endothelial function. In vitro studies suggest a number of potential mechanisms by which dietary nitrate and its sequential reduction to NO may reduce blood pressure and improve endothelial function, such as: acting as a substrate for endothelial NO synthase; increasing vasodilation; inhibiting mitochondrial reactive oxygen species production and platelet aggregation. In conclusion, the evidence for beneficial effects of dietary nitrate on blood pressure and endothelial function is promising. Further long-term randomised controlled human intervention studies assessing the potential effects of dietary nitrate on blood pressure and endothelial function are needed, particularly in individuals with hypertension and at risk of CVD.

The prevalence of abnormal pulse wave velocity, pulse contour analysis and ankle-brachial index in patients with livedo reticularis: a controlled study

OBJECTIVE

To evaluate the prevalence of abnormal pulse wave velocity (PWV), pulse contour analysis (PCA) and abnormal ankle-brachial pressure index (ABPI) in patients with livedo reticularis (livedo) and without livedo.

METHODS

We recruited 74 patients, of whom 41 had livedo: 16 APS, 9 APS with SLE and 16 with livedo (negative for aPL or lupus). The other group of 33 patients without livedo consisted of 10 APS, 8 APS with SLE and 15 with SLE only. Livedo was diagnosed and confirmed by a dermatologist. PWV was assessed in fasting patients by the Micro Medical PulseTrace analyser using a 4 MHz continuous-wave directional Doppler probe and digital PCA was analysed by Micro Medical PulseTrace by the same operator. Chi-square with Yates's correction was used for comparing results.

RESULTS

The median age of the livedo patients was 46 (29-71) years and of the non-livedo patients was 45 (25-68) years. Abnormal values of PWV in 10/41 (24.40%), ABPI in 4/41 (9.8%) and PCA in 10/41 (24.40%) patients were observed in the livedo group and in the non-livedo group abnormal values of PWV in 1/33 (P ≤ 0.025), ABPI in 0/33 (P = NS) and PCA in 5/33 (P = NS) were observed.

CONCLUSION

Patients with livedo reticularis are more likely to have abnormal PWV, indicating arterial stiffness.

New methodological approach to improve reproducibility of brachial artery flow-mediated dilatation

BACKGROUND

Measurement of flow-mediated dilation (FMD) is well known as a noninvasive method for an assessment of vascular endothelial function. However, the reproducibility is a major issue of FMD measurement. The purpose of this study is to examine the reproducibility of the new FMD measurement with medial epicondyle method.

METHODS

First, to evaluate the variability of the brachial artery diameter, 23 volunteers recruited from 32 healthy volunteers were examined for a brachial artery diameter at rest using with FMD equipment. Second, to evaluate the reproducibility of the FMD measurement, all volunteers underwent the FMD measurement, which was repeated at 2-week interval using the traditional method and the medial epicondyle method. The reproducibility in both methods was evaluated by 2 independent observers who measured on the same subject to assess the inter-observer reproducibility, and 1 observer who measured the same subject twice to assess the intra-observer reproducibility regarding the baseline value of arterial diameter and FMD.

RESULTS

The variability of brachial artery diameter was 0.57 ± 0.27 mm in 23 healthy volunteers. In the study of inter- and intra-observer reproducibility, 2 parameters including intra-class correlation coefficient and Pearson's correlation coefficient by medial epicondyle method are superior to those by traditional method.

CONCLUSIONS

These results suggest that medial epicondyle methodological approach to measure FMD is superior to traditional method.

Variability and reproducibility of flow-mediated dilatation in a multicentre clinical trial

AIMS

The aim of this study was to assess the reproducibility of flow-mediated dilatation (FMD) in a multicentre setting.

METHODS AND RESULTS

This study was performed as part of the dal-VESSEL trial in which FMD was measured in 19 vascular imaging centres in six European countries. A subgroup of patients who were allocated in the placebo group and scanned twice at each trial time point (substudy) was analysed. Intra-sonographer variability was calculated from FMD measurements 48 h apart. Centre variability and short-, medium-, and long-term reproducibility of FMD were calculated at 48 h and at 3 and 9 months intervals, respectively. Intra- and inter-reader variability was assessed by re-analysing the FMD images by three certified readers at two time intervals, 7 days apart. Sixty-seven patients were included. Variability between centres was comparable at 48 h and 3 months interval but almost doubled at 9 months. The mean absolute difference in %FMD was 1.04, 0.99, and 1.45% at the three time intervals, respectively. Curves were generated to indicate the number of patients required for adequate power in crossover and parallel study designs.

CONCLUSION

This study demonstrates for the first time that in a multicentre setting reproducible FMD measurements can be achieved for short- and medium-term evaluation, which are comparable with those reported from specialized laboratories. These findings justify the use of FMD as an outcome measure for short- and medium-term assessment of pharmacological interventions.

Endothelial function in women with and without a history of glucose intolerance in pregnancy

BACKGROUND/AIMS

Gestational diabetes mellitus (GDM) and milder gestational impaired glucose tolerance (GIGT) identify women who are at risk of developing cardiovascular disease. Endothelial dysfunction, as indicated by impaired flow-mediated dilatation (FMD) on brachial artery ultrasound, is an early marker of vascular disease. Thus, we sought to evaluate endothelial function in women with and without recent glucose intolerance in pregnancy.

METHODS

One-hundred and seventeen women underwent oral glucose tolerance testing (OGTT) in pregnancy, enabling stratification into those with normal gestational glucose tolerance (n = 59) and those with GDM or GIGT (n = 58). 6 years postpartum, they underwent a repeat of OGTT and brachial artery FMD studies, enabling assessment of FMD and 4 secondary vascular measures: FMD after 60 seconds (FMD60), baseline arterial diameter, peak shear rate, and reactive hyperemia.

RESULTS

There were no differences between the normal gestational glucose tolerance and GDM/GIGT groups in FMD (mean 8.5 versus 9.3%, P = 0.61), FMD60 (4.1 versus 5.1%, P = 0.33), baseline diameter (3.4 versus 3.4 mm, P = 0.66), peak shear rate (262.6 versus 274.8 s(-1), P = 0.32), and reactive hyperemia (576.6 versus 496.7%, P = 0.07). After covariate adjustment, there were still no differences between the groups.

CONCLUSION

Despite their long-term cardiovascular risk, women with glucose intolerance in pregnancy do not display endothelial dysfunction 6 years postpartum.

Endothelial function in HIV-infected patients switching from a boosted protease inhibitor-based regimen to raltegravir: a substudy of the SPIRAL study

OBJECTIVES

Raltegravir has been demonstrated to have a favourable impact on several metabolic parameters, including a lack of changes in lipid and glucose concentrations. We aimed to assess the effect on endothelial function of switching from a ritonavir-boosted protease inhibitor (PI/r)-based regimen to raltegravir.

METHODS

This is a substudy of the SPIRAL study, a multicentre, randomized, open-label clinical trial including HIV-infected patients on a stable PI/r-based antiretroviral regimen and virologically suppressed for at least the previous 6 months. Endothelial function was prospectively evaluated through flow-mediated dilatation (FMD) of the brachial artery at baseline and at weeks 24 and 48.

RESULTS

Thirty-five HIV-infected patients were included. Sixteen patients were randomly assigned to continue their current PI/r regimen and 19 to switch the PI/r to raltegravir. Total cholesterol, low-density lipoprotein cholesterol and triglycerides decreased at weeks 16 and 32 in the raltegravir-switch arm, while no changes were observed in the PI/r arm. Triglyceride levels were significantly lower in the raltegravir arm than in the PI/r arm at weeks 16, 32 and 48. No significant changes from baseline occurred in FMD at weeks 24 and 48 within or between the raltegravir and PI/r arms. Adjustment for baseline artery diameter did not have a significant effect on the FMD differences.

CONCLUSIONS

Switching from a PI/r-based antiretroviral regimen to raltegravir in patients with virological suppression has a beneficial impact on the lipid profile, but it does not seem to have a clear impact on endothelial function after a 1 year follow-up.

Arterial structure and function in ambulatory adolescents with cerebral palsy are not different from healthy controls

Physical inactivity in youth with cerebral palsy (CP) places them at increased risk of developing cardiovascular disease. The current study assessed indices of arterial health in adolescents with CP, classified as levels I-II of the Gross Motor Function Classification System (GMFCS) (n = 11, age 13.2 ± 2.1 yr), in comparison to age- and sex-matched controls (n = 11, age 12.4 ± 2.3 yr). Groups were similar in anthropometric measurements, resting blood pressures, and heart rates. There were no group differences in brachial flow-mediated dilation (11.1 ± 7.8 versus 6.1 ± 3.6), carotid intima-media thickness (0.42 ± 0.04 versus 0.41 ± 0.03 mm), and distensibility (0.008 ± 0.002 versus 0.008 ± 0.002 mmHg) or central (4.3 ± 0.6 versus 4.1 ± 0.9 m/s) and peripheral pulse wave velocity (7.1 ± 1.7 versus 7.6 ± 1.1 m/s); CP versus healthy controls, respectively. Vigorous intensity physical activity (PA) was lower in the CP group (CP: 38 ± 80 min versus controls: 196 ± 174 min); groups were similar in light and moderate intensity PA levels. Arterial health of ambulatory youth with CP is not different from a control group despite lower vigorous PA levels. Similar studies need to examine individuals with more pronounced mobility limitations (GMFCS level III–V).