Microvascular function predicts cardiovascular events in primary prevention: long-term results from the Firefighters and Their Endothelium (FATE) study

Effects of high-intensity aerobic interval training on cardiovascular disease risk in testicular cancer survivors: A phase 2 randomized controlled trial

BACKGROUND

Testicular cancer survivors (TCS) have an increased risk of treatment-related cardiovascular disease (CVD), which may limit their overall survival. We evaluated the effects of high-intensity aerobic interval training (HIIT) on traditional and novel CVD risk factors and surrogate markers of mortality in a population-based sample of TCS.

METHODS

This phase 2 trial (ClinicalTrials.gov identifier NCT02459132) randomly assigned 63 TCS to usual care (UC) or 12 weeks of supervised HIIT (ie, alternating periods of vigorous-intensity and light-intensity aerobic exercise). The primary outcome was peak aerobic fitness (VO_2peak ) assessed via a treadmill-based maximal cardiorespiratory exercise test. Secondary endpoints included CVD risk (eg, Framingham Risk Score), arterial health, parasympathetic nervous system function, and blood-based biomarkers.

RESULTS

Postintervention VO_2peak data were obtained for 61 participants (97%). HIIT participants attended 99% of the exercise sessions and achieved 98% of the target exercise intensity. Analysis of covariance demonstrated that HIIT was superior to UC for improving VO_2peak (adjusted between-group mean difference, 3.7 mL O₂ /kg/min; 95% confidence interval, 2.4-5.1 [P<.001]) and multiple secondary outcomes including CVD risk (P = .011), arterial thickness (P<.001), arterial stiffness (P<.001), postexercise parasympathetic reactivation (P = .001), inflammation (P = .045), and low-density lipoprotein (P = .014). Overall, HIIT reduced the prevalence of modifiable CVD risk factors by 20% compared with UC.

CONCLUSIONS

This randomized trial provides the first evidence that HIIT improves cardiorespiratory fitness, multiple pathways of CVD risk, and surrogate markers of mortality in TCS. These findings have important implications for the management of TCS. Further research concerning the long-term effects of HIIT on CVD morbidity and mortality in TCS is warranted. Cancer 2017;123:4057-65. © 2017 American Cancer Society.

The potential role of endothelial dysfunction and platelet activation in the development of thrombotic risk in COPD patients

INTRODUCTION

Despite lack of knowledge in the field, several studies have underlined the role of endothelium dysfunction and platelet activation as significant players in the development and progression of chronic obstructive pulmonary disease (COPD). Indeed, endothelium plays a crucial role in vascular homeostasis and impairment, due to the inflammation process enhanced by smoking. Chronic inflammation and endothelial dysfunction have been proved to drive platelet activity. Consequently, thrombotic risk is enhanced in COPD, and might explain the higher percentage of cardiovascular death in such patients. Areas covered: This review aims to clarify the role of endothelium function and platelet hyper-activity as the pathophysiological mechanisms of the increased thrombotic risk in COPD. Expert commentary: In COPD patients, chronic inflammation does not impact only on lung parenchyma, but potentially involves all systems, including the endothelium of blood vessels. Impaired endothelium has several consequences, such as reduced vasodilatation capacity, enhanced blood coagulation, and increased platelet activation resulting in higher risk of thrombosis in COPD patients. Endothelium dysfunction and platelet activation are potential targets of therapy in patients with COPD aiming to reduce their risk of cardiovascular events.

Targeting vascular (endothelial) dysfunction

Cardiovascular diseases are major contributors to global deaths and disability-adjusted life years, with hypertension a significant risk factor for all causes of death. The endothelium that lines the inner wall of the vasculature regulates essential haemostatic functions, such as vascular tone, circulation of blood cells, inflammation and platelet activity. Endothelial dysfunction is an early predictor of atherosclerosis and future cardiovascular events. We review the prognostic value of obtaining measurements of endothelial function, the clinical techniques for its determination, the mechanisms leading to endothelial dysfunction and the therapeutic treatment of endothelial dysfunction. Since vascular oxidative stress and inflammation are major determinants of endothelial function, we have also addressed current antioxidant and anti-inflammatory therapies. In the light of recent data that dispute the prognostic value of endothelial function in healthy human cohorts, we also discuss alternative diagnostic parameters such as vascular stiffness index and intima/media thickness ratio. We also suggest that assessing vascular function, including that of smooth muscle and even perivascular adipose tissue, may be an appropriate parameter for clinical investigations.

LINKED ARTICLES

This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.

Microvascular Function Contributes to the Relation Between Aortic Stiffness and Cardiovascular Events: The Framingham Heart Study

BACKGROUND

Arterial dysfunction contributes to cardiovascular disease (CVD) progression and clinical events. Inter-relations of aortic stiffness and vasodilator function with incident CVD remain incompletely studied.

METHODS AND RESULTS

We used proportional hazards models to relate individual measures of vascular function to incident CVD in 4547 participants (mean age, 51±11 years; 54% women) in 2 generations of Framingham Heart Study participants. During follow-up (0.02-13.83 years), 232 participants (5%) experienced new-onset CVD events. In multivariable models adjusted for cardiovascular risk factors, both higher carotid-femoral pulse wave velocity (hazard ratio [HR], 1.32; 95% confidence interval [CI], 1.07-1.63; P=0.01) and lower hyperemic mean flow velocity (HR, 0.84; 95% CI, 0.71-0.99; P=0.04) were associated significantly with incident CVD, whereas primary pressure wave amplitude (HR, 1.12; 95% CI, 0.99-1.27; P=0.06), baseline brachial diameter (HR, 1.09; 95% CI, 0.90-1.31; P=0.39), and flow-mediated vasodilation (HR, 0.85; 95% CI, 0.69-1.04; P=0.12) were not. In mediation analyses, 8% to 13% of the relation between aortic stiffness and CVD events was mediated by hyperemic mean flow velocity.

CONCLUSIONS

Our results suggest that associations between aortic stiffness and CVD events are mediated by pathways that include microvascular damage and remodeling.

Clustering of cardiovascular risk factors and carotid intima-media thickness: The USE-IMT study

Background

The relation of a single risk factor with atherosclerosis is established. Clinically we know of risk factor clustering within individuals. Yet, studies into the magnitude of the relation of risk factor clusters with atherosclerosis are limited. Here, we assessed that relation.

Methods

Individual participant data from 14 cohorts, involving 59,025 individuals were used in this cross-sectional analysis. We made 15 clusters of four risk factors (current smoking, overweight, elevated blood pressure, elevated total cholesterol). Multilevel age and sex adjusted linear regression models were applied to estimate mean differences in common carotid intima-media thickness (CIMT) between clusters using those without any of the four risk factors as reference group.

Results

Compared to the reference, those with 1, 2, 3 or 4 risk factors had a significantly higher common CIMT: mean difference of 0.026 mm, 0.052 mm, 0.074 mm and 0.114 mm, respectively. These findings were the same in men and in women, and across ethnic groups. Within each risk factor cluster (1, 2, 3 risk factors), groups with elevated blood pressure had the largest CIMT and those with elevated cholesterol the lowest CIMT, a pattern similar for men and women.

Conclusion

Clusters of risk factors relate to increased common CIMT in a graded manner, similar in men, women and across race-ethnic groups. Some clusters seemed more atherogenic than others. Our findings support the notion that cardiovascular prevention should focus on sets of risk factors rather than individual levels alone, but may prioritize within clusters.

Effect of gender and adiposity on in vivo vascular function in young African Americans

The relationship between obesity and high blood pressure is not as strong among African Americans (AA) as compared to Caucasians. We designed the current study to determine the effect of adiposity on vascular endothelial function (a harbinger of hypertension) among young healthy AA without additional cardiovascular disease risk factors. A total of 108 AA subjects (46 women) between the ages of 18 and 45 years were recruited. All the subjects were normotensive, nonsmokers, and normoglycemic. Anthropometric and cardiovascular disease risk factor measurements (lipid, insulin resistance, and inflammatory markers) were obtained. Vascular endothelial function was measured by brachial artery flow-mediated dilation (FMD). Adiposity distribution was measured by using magnetic resonance imaging scan. There were no gender differences in age and levels of blood pressure, lipids, insulin resistance, and inflammatory markers. Women had higher total body fat percentage and higher peripheral adiposity compared to men. We observed that total and central adiposity did not correlate significantly with brachial artery FMD in women (r = -0.12 and r = 0.23, respectively; P = NS). However, in men, waist circumference was positively associated with FMD (r = 0.3, P ≤ .05). Hyperemic flow was negatively correlated significantly with total and central adiposity in men (r = -0.34 and r = -0.48, respectively; P < .05), but not in women (r = -0.26 and r = 0.03, respectively; P = NS). Our study suggests that increased adiposity may pose greater risk to AA men compared to AA women by adversely affecting resistance vessel function (as measured by hyperemic flow). Larger studies are necessary to validate these findings.

Sex differences in vascular dysfunction and cardiovascular outcomes: The cardiac, endothelial function, and arterial stiffness in ESRD (CERES) study

INTRODUCTION

Recent studies suggest that women with end-stage renal disease (ESRD) may have higher rates of mortality than men, but it is unknown whether sex differences in vascular function explain this disparity. The cardiac, endothelial function, and arterial stiffness in ESRD (CERES) study is an ongoing, prospective observational study designed to investigate vascular function, myocardial injury, and cardiovascular outcomes in ESRD.

METHODS

Among 200 CERES participants (34% women), we evaluated arterial wave reflections as augmentation index normalized to a heart rate of 75 (AIx75), arterial stiffness as pulse wave velocity, and macro- and microvascular endothelial dysfunction as flow-mediated dilation and velocity time integral (VTI). Over a median of 14 months, participants were followed for the composite outcome of cardiovascular hospitalization or all-cause death.

FINDINGS

Women had higher arterial wave reflection (Mean, SD AIx75 30% ± 9% for women vs. 21% ± 10% for men; P < 0.001) and worse microvascular function (VTI 55 ± 30 cm for women vs. 70 ± 27 cm for men; P = 0.007). After multivariable adjustment, female sex remained associated with a 0.5-SD higher AIx75 (95% CI [0.01, 0.9]) and 0.3-SD lower VTI (95%CI [0.1, 0.7]). Women experienced higher adjusted rates of the composite outcome (HR 2.5; 95%CI [1.1, 5.6]; P = 0.03), and further adjustment for arterial wave reflection attenuated this risk.

DISCUSSION

Vascular dysfunction may partly explain the association of female sex with higher cardiovascular risk and mortality in patients with ESRD. Further studies are needed to explore whether sex differences in vascular function predict long-term outcomes, and whether hormonal or inflammatory factors explain these associations.

Cardiovascular Consequences of Binge Drinking: An Integrative Review with Implications for Advocacy, Policy, and Research

Worldwide, binge drinking is a major public health problem. The popularized health risks associated with binge drinking include physical injury and motor vehicle crashes; less attention has been given to the negative effects on the cardiovascular (CV) system. The primary aims of this review were to provide a summary of the adverse effects of binge drinking on the risk and development of CV disease and to review potential pathophysiologic mechanisms. Using specific inclusion criteria, an integrative review was conducted that included data from human experimental, prospective cross-sectional, and cohort epidemiological studies that examined the association between binge drinking and CV conditions such as hypertension (HTN), myocardial infarction (MI), stroke, and arrhythmias. Studies were identified that examined the relationship between binge drinking and CV outcomes. Collectively, findings support that binge drinking is associated with a higher risk of pre-HTN, HTN, MI, and stroke in middle-aged and older adults. Binge drinking may also have adverse CV effects in young adults (aged 18 to 30). Mechanisms remain incompletely understood; however, available evidence suggests that binge drinking may induce oxidative stress and vascular injury and be proatherogenic. Public health messages regarding binge drinking need to include the effects of binge drinking on the CV system.

Imaging Subclinical Atherosclerosis: Where Do We Stand?

The age of initiation and the rate of progression of atherosclerosis vary markedly among individuals and have been difficult to predict with traditional cardiovascular risk assessment models. Although these risk models provide good discrimination and calibration in certain populations, cardiovascular disease (CVD) risk may not be accurately estimated in low- and intermediate risk individuals. Therefore, imaging techniques such as Ankle-Brachial Index (ABI), Coronary Artery Calcium score (CAC), carotid Intima-Media Thickness (cIMT), flow mediated dilation (FMD) and Positron Emission Tomography (PET) have been developed and used to reclassify these individuals. In the present article we review the role of the most commonly used imaging techniques for CVD risk assessment.

Influence of sex on microvascular and macrovascular responses to prolonged sitting

Increased daily sitting time is associated with greater cardiovascular risk, and, on average, women are more sedentary than men. Recent reports have demonstrated that prolonged sitting reduces lower leg microvascular (reactive hyperemia) and macrovascular [flow-mediated dilation (FMD)] vasodilator function. However, these studies have predominately included men, and the effects of sitting in young women are largely unexplored. This becomes important given known sex differences in vascular function. Thus, herein, we assessed popliteal artery reactive hyperemia and FMD before and after a 3-h sitting period in healthy young women (n = 12) and men (n = 8). In addition, resting popliteal artery hemodynamics (duplex Doppler ultrasound) and calf circumference were measured before, during, and after sitting. Resting popliteal artery shear rate was reduced to a similar extent in both groups during the sitting period (women: -48.5 ± 8.4 s^-1 and men: -52.9 ± 12.3 s^-1, P = 0.45). This was accompanied by comparable increases in calf circumference in men and women (P = 0.37). After the sitting period, popliteal artery FMD was significantly reduced in men (PreSit: 5.5 ± 0.9% and PostSit: 1.6 ± 0.4%, P < 0.001) but not women (PreSit: 4.4 ± 0.6% and PostSit: 3.6 ± 0.6%, P = 0.29). In contrast, both groups demonstrated similar reductions in hyperemic blood flow area under the curve (women: -28,860 ± 5,742 arbitrary units and men: -28,691 ± 9,685 arbitrary units, P = 0.99), indicating impaired microvascular reactivity after sitting. These findings indicate that despite comparable reductions in shear rate during 3 h of uninterrupted sitting, macrovascular function appears protected in some young women but the response was variable, whereas men exhibited more consistent reductions in FMD. In contrast, the leg microvasculature is susceptible to similar sitting-induced impairments in men and women.NEW & NOTEWORTHY We demonstrate that leg macrovascular function was consistently reduced in young men but not young women after prolonged sitting. In contrast, both men and women exhibited similar reductions in leg microvascular reactivity after sitting. These data demonstrate, for the first time, sex differences in vascular responses to prolonged sitting.

Delivery of small-for-gestational-age neonate and association with early-onset impaired maternal endothelial function

OBJECTIVE

Women who have delivered a small-for-gestational-age (SGA) infant are at an increased risk of developing cardiovascular disease (CVD) in later life. Endothelial dysfunction is a subclinical sign of early CVD. It is unknown whether women who have recently had a pregnancy complicated by SGA, in the absence of other maternal and fetal diseases, have subclinical endothelial dysfunction. Our aim was to assess maternal endothelial function 6 months after a pregnancy complicated by SGA.

METHODS

This was a case-control study conducted in a tertiary referral hospital in London, UK, over a 15-month period. Flow-mediated dilatation (FMD) of the brachial artery was measured in women 6.9 ± 2.5 months after childbirth. Forty-four women were included in the study, of whom 15 had a SGA neonate (mean ± SD customized birth centile of 1.9 ± 2.3) and 29 delivered an appropriately grown baby (mean ± SD customized birth centile of 47.5 ± 26.3). The primary continuous variable, FMD, was assessed in each group and compared using unpaired t-test.

RESULTS

Women who had a SGA neonate had lower postpartum FMD (6.79 ± 0.95%) than did those who had an appropriately grown offspring (10.26 ± 2.44% (95% CI for difference between groups, -5.37 to -1.57); P = 0.0007). There were no differences in postnatal maternal blood pressure, abdominal circumference, weight and glucose, insulin and lipid profiles between the two groups.

CONCLUSIONS

Women who had a pregnancy affected by SGA, probably due to placental failure in the absence of pre-eclampsia, have evidence of subclinical endothelial dysfunction within 6 months of childbirth. These women may benefit from lifestyle measures focused on the primary prevention of CVD. Further research in larger populations is needed to ascertain if such postpartum maternal endothelial dysfunction is a pregnancy-induced phenomenon or if it is related to the pre-existing maternal phenotype, and whether it persists long term. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Vascular hyperpolarization in human physiology and cardiovascular risk conditions and disease

Hyperpolarization causing smooth muscle relaxation contributes to the maintenance of vascular homeostasis, particularly in small-calibre arteries and arterioles. It may also become a compensatory vasodilator mechanism upregulated in states with impaired nitric oxide (NO) availability. Bioassay of vascular hyperpolarization in the human circulation has been hampered by the complexity of mechanisms involved and the limited availability of investigational tools. Firm evidence, however, supports the notion that hyperpolarization participates in the regulation of resting vasodilator tone and vascular reactivity in healthy subjects. In addition, an enhanced endothelium-derived hyperpolarization contributes to both resting and agonist-stimulated vasodilation in a variety of cardiovascular risk conditions and disease. Thus, hyperpolarization mediated by epoxyeicosatrienoic acids (EETs) and H₂ O₂ has been observed in coronary arterioles of patients with coronary artery disease. Similarly, ouabain-sensitive and EETs-mediated hyperpolarization has been observed to compensate for NO deficiency in patients with essential hypertension. Moreover, in non-hypertensive patients with multiple cardiovascular risk factors and in hypercholesterolaemia, K_Ca channel-mediated vasodilation appears to be activated. A novel paradigm establishes that perivascular adipose tissue (PVAT) is an additional regulator of vascular tone/function and endothelium is not the only agent in vascular hyperpolarization. Indeed, some PVAT-derived relaxing substances, such as adiponectin and angiotensin 1-7, may exert anticontractile and vasodilator actions by the opening of K_Ca channels in smooth muscle cells. Conversely, PVAT-derived factors impair coronary vasodilation via differential inhibition of some K⁺ channels. In view of adipose tissue abnormalities occurring in human obesity, changes in PVAT-dependent hyperpolarization may be relevant for vascular dysfunction also in this condition.

Role of T-Cell Dysfunction, Inflammation, and Coagulation in Microvascular Disease in HIV

BACKGROUND

Compared to uninfected adults, HIV-infected adults on antiretroviral therapy are at increased risk of cardiovascular disease. Given the increase in T-cell dysfunction, inflammation, and coagulation in HIV infection, microvascular dysfunction is thought to contribute to this excess cardiovascular risk. However, the relationships between these variables remain undefined.

METHODS AND RESULTS

This was a cross-sectional study of 358 HIV-infected adults from the SCOPE cohort. Macrovascular endothelial function was assessed using flow-mediated dilation of the brachial artery and microvascular function by reactive hyperemia. T-cell phenotype was determined by flow cytometry. Plasma markers of inflammation (tumor necrosis factor-α, interleukin-6, high-sensitivity C-reactive protein, sCD14) and coagulation (fibrinogen, D-dimer) were also measured. In all HIV+ subjects, markers of inflammation (tumor necrosis factor-α, high-sensitivity C-reactive protein), coagulation (D-dimer) and T-cell activation (CD8+PD1+, CD4+interferon+cytomegalovirus-specific) were associated with worse reactive hyperemia after adjusting for traditional cardiovascular risk factors and co-infections. In treated and suppressed subjects, tumor necrosis factor-α and CD8+PD1+ cells remained associated with worse reactive hyperemia after adjustment. Compared to the untreated subjects, CD8+PD1+ cells were increased in the virally suppressed group. Reactive hyperemia was predictive of flow-mediated dilation.

CONCLUSIONS

CD8+PD1+ cells and tumor necrosis factor-α were associated with microvascular dysfunction in all HIV+ subjects and the treated and suppressed group. Additionally, D-dimer, high-sensitivity C-reactive protein, sCD-14, and interleukin-6 were associated with microvascular dysfunction in all HIV+ subjects. Although T-cell dysfunction, inflammation, and microvascular dysfunction are thought to play a role in cardiovascular disease in HIV, this study is the first to look at which T-cell and inflammatory markers are associated with microvascular dysfunction in HIV-infected individuals.

Exercise-induced heat stress disrupts the shear-dilatory relationship

NEW FINDINGS

What is the central question of this study? Although heat stress is known to increase cardiovascular strain, no study, to date, had explored the potential impact of exercise-induced heat stress on vascular function. What is the main finding and its importance? We found that acute exercise tended to reduce flow-mediated dilatation (FMD), owing in part to reduced reactive hyperaemia/shear stimulus; thus, when FMD is normalized to shear no postexercise deficit exists. Exercise-induced heat stress increased reactive hyperaemia, shear rate, coupled with a sustained FMD postexercise, suggests that exercise-induced heat stress increases the amount of shear stimulus to elicit a similar response, indicating reduced vascular responsiveness, or reserve, which might increase cardiovascular susceptibility. Heat stress increases cardiovascular strain and is of particular concern in occupations, such as firefighting, in which individuals are required to perform strenuous work while wearing personal protective equipment. Sudden cardiac events are associated with strenuous activity and are the leading cause of duty-related death among firefighters, accounting for ∼50% of duty-related fatalities per year. Understanding the acute effects of exercise-induced heat stress (EIHS) on vascular endothelial function may provide insight into the mechanisms precipitating acute coronary events in firefighters. The purpose of this study, therefore, was to determine the effects of EIHS on vascular endothelial function. Using a balanced crossover design, 12 healthy men performed 100 min of moderate-intensity, intermittent exercise with and without EIHS (personal protective equipment or cooling vest, respectively). Measurements of flow-mediated dilatation (FMD), reactive hyperaemia and shear rate area under the curve (SR_AUC ) were performed pre- and postexercise. During EIHS, core temperature was significantly higher (38 ± 0.1 versus 37 ± 0.1°C). Postexercise FMD tended to be suppressed in both conditions, but was not different from pre-exercise. Reactive hyperaemia was reduced after no-EIHS but increased after EIHS. Thus, normalizing FMD to the shear stimulus (FMD/SR_AUC ) revealed a significant reduction in FMD after EIHS only (pre-exercise 0.15 ± 0.04 and 0.13 ± 0.02 s^-1 versus postexercise, 0.13 ± 0.02 and 0.06 ± 0.02 s^-1 , no-EIHS and EIHS, respectively). We conclude that moderate heat stress superimposed on moderate-intensity exercise resulted in reduced vascular endothelial function. This heat stress-induced alteration in the shear-dilatory relationship may relate to the increased risk of acute coronary events associated with activities that combine physical exertion and heat stress (i.e. firefighting).

Effect of exercise-induced muscle damage on vascular function and skeletal muscle microvascular deoxygenation

This paper investigated the effects of unaccustomed eccentric exercise‐induced muscle damage (EIMD) on macro‐ and microvascular function. We tested the hypotheses that resting local and systemic endothelial‐dependent flow‐mediated dilation (FMD) and microvascular reactivity would decrease, V˙O2max would be altered, and that during ramp exercise, peripheral O₂ extraction, evaluated via near‐infrared‐derived spectroscopy (NIRS) derived deoxygenated hemoglobin + myoglobin ([HHb]), would be distorted following EIMD. In 13 participants, measurements were performed prior to (Pre) and 48 h after a bout of knee extensor eccentric exercise designed to elicit localized muscle damage (Post). Flow‐mediated dilation and postocclusive reactive hyperemic responses measured in the superficial femoral artery served as a measurement of local vascular function relative to the damaged tissue, while the brachial artery served as an index of nonlocal, systemic, vascular function. During ramp‐incremental exercise on a cycle ergometer, [HHb] and tissue saturation (TSI%) in the m. vastus lateralis were measured. Superficial femoral artery FMD significantly decreased following EIMD (pre 6.75 ± 3.89%; post 4.01 ± 2.90%; P < 0.05), while brachial artery FMD showed no change. The [HHb] and TSI% amplitudes were not different following EIMD ([HHb]: pre, 16.9 ± 4.7; post 17.7 ± 4.9; TSI%: pre, 71.0 ± 19.7; post 71.0 ± 19.7; all P > 0.05). At each progressive increase in workload (i.e., 0–100% peak), the [HHb] and TOI% responses were similar pre‐ and 48 h post‐EIMD (P > 0.05). Additionally, V˙O2max was similar at pre‐ (3.0 ± 0.67 L min⁻¹) to 48 h post (2.96 ± 0.60 L min⁻¹)‐EIMD (P > 0.05). Results suggest that moderate eccentric muscle damage leads to impaired local, but not systemic, macrovascular dysfunction.

Acute limb heating improves macro- and microvascular dilator function in the leg of aged humans

Local heating of an extremity increases blood flow and vascular shear stress throughout the arterial tree. Local heating acutely improves macrovascular dilator function in the upper limbs of young healthy adults through a shear stress-dependent mechanism but has no such effect in the lower limbs of this age group. The effect of acute limb heating on dilator function within the atherosclerotic prone vasculature of the lower limbs of aged adults is unknown. Therefore, the purpose of this study was to test the hypothesis that acute lower limb heating improves macro- and microvascular dilator function within the leg vasculature of aged adults. Nine young and nine aged adults immersed their lower limbs at a depth of ~33 cm into a heated (~42°C) circulated water bath for 45 min. Before and 30 min after heating, macro (flow-mediated dilation)- and microvascular (reactive hyperemia) dilator functions were assessed in the lower limb, following 5 min of arterial occlusion, via Doppler ultrasound. Compared with preheat, macrovascular dilator function was unchanged following heating in young adults (P = 0.6) but was improved in aged adults (P = 0.04). Similarly, microvascular dilator function, as assessed by peak reactive hyperemia, was unchanged following heating in young adults (P = 0.1) but was improved in aged adults (P < 0.01). Taken together, these data suggest that acute lower limb heating improves both macro- and microvascular dilator function in an age dependent manner.

NEW & NOTEWORTHY

We demonstrate that lower limb heating acutely improves macro- and microvascular dilator function within the atherosclerotic prone vasculature of the leg in aged adults. These findings provide evidence for a potential therapeutic use of chronic lower limb heating to improve vascular health in primary aging and various disease conditions.

Clopidogrel Improves Skin Microcirculatory Endothelial Function in Persons With Heightened Platelet Aggregation

Background

Platelet activation can lead to enhanced oxidative stress, inflammatory response, and endothelial dysfunction. To quantify the effects of platelet inhibition on endothelial function, we assessed platelet activity of healthy persons before and after clopidogrel administration and evaluated its effects on endothelial function. We hypothesized that clopidogrel, by attenuating platelet activity, would result in enhanced endothelial function.

Methods and Results

Microcirculatory endothelial function was quantified by laser Doppler flowmetry (LDF) mediated by thermal hyperemia (TH) and postocclusive reactive hyperemia, respectively, in 287 and 241 relatively healthy and homogenous Old Order Amish persons. LDF and platelet aggregation measures were obtained at baseline and after 7 days of clopidogrel administration. Our primary outcome was percentage change in post‐ versus preclopidogrel LDF measures. Preclopidogrel TH‐LDF and platelet aggregation were higher in women than in men (P<0.001). Clopidogrel administration was associated with ≈2‐fold higher percentage change in TH‐LDF in participants with high versus low baseline platelet aggregation (39.4±10.1% versus 17.4±5.6%, P=0.03). Clopidogrel also increased absolute TH‐LDF measures in persons with high platelet aggregation (1757±766 to 2154±1055, P=0.03), with a more prominent effect in women (1909±846 to 2518±1048, P=0.001). There was no evidence that clopidogrel influenced postocclusive reactive hyperemia LDF measures.

Conclusions

The administration of clopidogrel in healthy persons with high baseline platelet aggregation results in improved TH‐induced microcirculatory endothelial function. These data suggest that clopidogrel may have a beneficial effect on microcirculatory endothelial function, presumably through antiplatelet activity, and may confer additional vascular benefits.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov. Unique identifier: NCT00799396.

Cross-Sectional Associations of Flow Reversal, Vascular Function, and Arterial Stiffness in the Framingham Heart Study

OBJECTIVE

Experimental studies link oscillatory flow accompanied by flow reversal to impaired endothelial cell function. The relation of flow reversal with vascular function and arterial stiffness remains incompletely defined.

APPROACH AND RESULTS

We measured brachial diastolic flow patterns along with vasodilator function in addition to tonometry-based central and peripheral arterial stiffness in 5708 participants (age 47±13 years, 53% women) in the Framingham Heart Study Offspring and Third Generation cohorts. Brachial artery diastolic flow reversal was present in 35% of the participants. In multivariable regression models, the presence of flow reversal was associated with lower flow-mediated dilation (3.9±0.2 versus 5.0±0.2%; P<0.0001) and reactive hyperemic flow velocity (50±0.99 versus 57±0.93 cm/s; P<0.0001). The presence of flow reversal (compared with absence) was associated with higher central aortic stiffness (carotid-femoral pulse wave velocity 9.3±0.1 versus 8.9±0.1 m/s), lower muscular artery stiffness (carotid-radial pulse wave velocity 9.6±0.1 versus 9.8±0.1 m/s), and higher forearm vascular resistance (5.32±0.03 versus 4.66±0.02 log dyne/s/cm⁵; P<0.0001). The relations of diastolic flow velocity with flow-mediated dilation, aortic stiffness, and forearm vascular resistance were nonlinear, with a steeper decline in vascular function associated with increasing magnitude of flow reversal.

CONCLUSIONS

In our large, community-based sample, brachial artery flow reversal was common and associated with impaired vasodilator function and higher aortic stiffness. Our findings are consistent with the concept that flow reversal may contribute to vascular dysfunction.

Short-term high salt intake reduces brachial artery and microvascular function in the absence of changes in blood pressure

OBJECTIVES

The aims of this study were to test the hypothesis that short-term high salt intake reduces macrovascular and microvascular endothelial function in the absence of changes in blood pressure and to determine whether acute exercise restores endothelial function after high salt in women.

MATERIALS AND METHODS

Twelve women were administered high salt (11 g of sodium chloride for 7 days) and then underwent a weightlifting session. Brachial artery flow-mediated dilation and nitroglycerin dilation were measured with ultrasound at baseline, after high salt, and after weightlifting. Subcutaneous fat tissue biopsies were obtained at baseline, after high salt, and after weightlifting. Resistance arteries from biopsies were cannulated for vascular reactivity measurements in response to flow [flow-induced dilation (FID)] and acetylcholine.

RESULTS

Blood pressure was similar before and after high salt diet. Brachial flow-mediated dilation was reduced after high salt diet but was not affected by acute weightlifting. Brachial nitroglycerin dilations were similar before and after high salt. FID and acetylcholine-induced dilation of resistance arteries were similar to that of before and after high salt diet. FID and acetylcholine-induced dilation was not altered by weightlifting after high salt diet. However, N-nitro-L-arginine methyl ester significantly reduced FID at baseline and after exercise but had no effect dilator reactivity after high salt diet alone.

CONCLUSION

These data suggest that high salt intake reduces brachial artery endothelial function and switches the mediator of vasodilation in the microcirculation to a non-nitric oxide-dependent mechanism in healthy adults and acute exercise may switch the dilator mechanism back to nitric oxide during high salt diet.

Microvascular dysfunction affects the development and prognosis of sudden idiopathic hearing loss

OBJECTIVE

The aim of our study is to investigate whether systemic microvascular function affects the development and prognosis of sudden idiopathic hearing loss (SHL).

TYPE OF STUDY

A prospective case-control study.

MATERIALS AND METHODS

Fifty patients diagnosed with SHL at our hospital between September 2015 and May 2016 were included as the SHL group, and 50 healthy volunteers who came to the hospital for medical screening were included in the control group. Thirty-one patients from the SHL group who responded to treatment and 19 patients who did not respond to treatment were identified according to the Siegel criteria and were grouped. Patients with comorbid disorders were excluded from the study. To determine microvascular function, the videocapillaroscopic examination was conducted from the nailfold, measuring the capillary density (CD) and post-occlusive reactive hyperaemia (PORH) values and statistical analysis was performed between the groups.

RESULT

While CD was an average of 83.1 ± 6 in the SHL group, it was measured as 96.2 ± 10 in the control group. The CD value was significantly lower in the SHL group than the control group (P < 0.05). While the average PORH value in the SHL group was 80.5 ± 7.7, it was measured as 97.5 ± 10 in the control group. The PORH value was significantly lower in the SHL group than the control group (P < 0.05). The CD value did not differ significantly (P > 0.05) between the group that responded to treatment (83.4 ± 5.5) and the group that did not respond to treatment (82.7 ± 6.9). The PORH value was significantly lower (P < 0.05) in the group that did not respond to treatment (75.2 ± 7.9) than the group that did (83.8 ± 5.6).

CONCLUSION

To our best knowledge, our study is the first study in the literature. Although the role of specific mechanisms in SHL is not entirely understood, the capillaroscopic examination can show the importance of microvascular function in SHL. CD and PORH values were found to be low in SHL patients, and a low PORH value was found to be a factor of poor prognosis.

Reactivity to low-flow as a potential determinant for brachial artery flow-mediated vasodilatation

Previous studies have reported a vasoconstrictor response in the radial artery during a cuff-induced low-flow condition, but a similar low-flow condition in the brachial artery results in nonuniform reactivity. This variable reactivity to low-flow influences the subsequent flow-mediated dilatation (FMD) response following cuff-release. However, it is uncertain whether reactivity to low-flow is important in data interpretation in clinical populations and older adults. This study aimed to determine the influence of reactivity to low-flow on the magnitude of brachial artery FMD response in middle-aged and older individuals with diverse cardiovascular risk profiles. Data were analyzed from 165 individuals, divided into increased cardiovascular risk (CVR: n = 115, 85M, 67.0 ± 8.8 years) and healthy control (CTRL: n = 50, 30M, 63.2 ± 7.2 years) groups. Brachial artery diameter and blood velocity data obtained from Doppler ultrasound were used to calculate FMD, reactivity to low-flow and estimated shear rate (SR) using semiautomated edge-detection software. There was a significant association between reactivity to low-flow and FMD in overall (r = 0.261), CTRL (r = 0.410) and CVR (r = 0.189, all P < 0.05) groups. Multivariate regression analysis found that reactivity to low-flow, peak SR, and baseline diameter independently contributed to FMD along with sex, the presence of diabetes, and smoking (total R(2) = 0.450). There was a significant association between reactivity to low-flow and the subsequent FMD response in the overall dataset, and reactivity to low-flow independently contributed to FMD These findings suggest that reactivity to low-flow plays a key role in the subsequent brachial artery FMD response and is important in the interpretation of FMD data.

Vascular function assessed by passive leg movement and flow-mediated dilation: initial evidence of construct validity

The vasodilatory response to passive leg movement (PLM) appears to provide a novel, noninvasive assessment of vascular function. However, PLM has yet to be compared with the established noninvasive assessment of vascular health, flow-mediated dilation (FMD). Therefore, as an initial evaluation of the construct validity of PLM and upright seated and supine PLM as well as brachial (BA) and superficial femoral (SFA) artery FMDs were performed in 10 young (22 ± 1) and 30 old (73 ± 2) subjects. During upright seated PLM, the peak change in leg blood flow (ΔLBF) and leg vascular conductance (ΔLVC) was significantly correlated with BA (r = 0.57 and r = 0.66) and SFA (r = 0.44 and r = 0.41, ΔLBF and ΔLVC, respectively) FMD. Furthermore, although the relationships were not as strong, the supine PLM response was also significantly correlated with BA (r = 0.38 and r = 0.35) and SFA (r = 0.39 and r = 0.35, ΔLBF and ΔLVC, respectively) FMD. Examination of the young and old separately, however, revealed that significant relationships persisted in both groups only for the upright seated PLM response and BA FMD (young: r = 0.73 and r = 0.77; old: r = 0.35 and r = 0.45, ΔLBF and ΔLVC, respectively). Normalizing FMD for shear rate during PLM abrogated all significant relationships between the PLM and FMD response, suggesting a role for nitric oxide (NO) in these associations. Collectively, these data indicate that PLM, particularly upright seated PLM, likely provides an index of vascular health analogous to the traditional FMD test. Given the relative ease of PLM implementation, these data have important positive implications for PLM as a clinical vascular health assessment.

Reactive hyperemia is associated with adverse clinical outcomes in heart failure

INTRODUCTION

Impaired endothelial function, as assessed by brachial artery flow-mediated dilation (FMD), is an established risk factor for cardiovascular events. FMD is impaired in heart failure (HF) patients, but less is known about hyperemic brachial artery flow. We investigated the relationship between FMD and hyperemic flow with adverse clinical outcomes in HF patients.

METHODS

Brachial artery FMD and hyperemic flow were assessed in 156 patients (70.5 % Male; 45.5% Caucasian; mean age (± SD) = 56.2 (±12.4) years) with HF and reduced left ventricular ejection fraction (LVEF). Cox proportional hazard models were used to assess the potential explanatory association of FMD and hyperemic flow with the composite outcome of death or cardiovascular hospitalization over a median 5-year follow-up period.

RESULTS

Both FMD and hyperemic flow were negatively correlated with age, but unrelated to sex, race, body mass index, LVEF or N-terminal pro-B-Type natriuretic peptide (NT-ProBNP). Reduced hyperemic flow, but not FMD, was associated with an increased risk of death or cardiac hospitalization after controlling for traditional risk factors.

CONCLUSION

The association of reduced hyperemic flow with increased risk of adverse clinical outcomes suggests that micro-vascular function may be an important prognostic marker in patients with HF.

Intermittent hypoxia and arterial blood pressure control in humans: role of the peripheral vasculature and carotid baroreflex

Intermittent hypoxia (IH) occurs in association with obstructive sleep apnea and likely contributes to the pathogenesis of hypertension. The purpose of this study was to examine the putative early adaptations at the level of the peripheral vasculature and carotid baroreflex (CBR) that may promote the development of hypertension. Ten healthy male participants (26 ± 1 yr, BMI = 24 ± 1 kg/m(2)) were exposed to 6 h of IH (1-min cycles of normoxia and hypoxia) and SHAM in a single-blinded, counterbalanced crossover study design. Ambulatory blood pressure was measured during each condition and the following night. Vascular strain of the carotid and femoral artery, a measure of localized arterial stiffness, and hemodynamic shear patterns in the brachial and femoral arteries were measured during each condition. Brachial artery reactive hyperemia flow-mediated vasodilation was assessed before and after each condition as a measure of endothelial function. CBR function and its control over leg vascular conductance (LVC) were measured after each condition with a variable-pressure neck chamber. Intermittent hypoxia 1) increased nighttime pulse pressure by 3.2 ± 1.3 mmHg, 2) altered femoral but not brachial artery hemodynamics, 3) did not affect brachial artery endothelial function, 4) reduced vascular strain in the carotid and possibly femoral artery, and 5) shifted CBR mean arterial pressure (MAP) to higher MAP while blunting LVC responses to CBR loading. These results suggest limb-specific vascular impairments, reduced vascular strain, and CBR resetting combined with blunted LVC responses are factors in the early pathogenesis of IH-induced development of hypertension.

Passive heat therapy improves endothelial function, arterial stiffness and blood pressure in sedentary humans

KEY POINTS

A recent 30 year prospective study showed that lifelong sauna use reduces cardiovascular-related and all-cause mortality; however, the specific cardiovascular adaptations that cause this chronic protection are currently unknown. We investigated the effects of 8 weeks of repeated hot water immersion ('heat therapy') on various biomarkers of cardiovascular health in young, sedentary humans. We showed that, relative to a sham group which participated in thermoneutral water immersion, heat therapy increased flow-mediated dilatation, reduced arterial stiffness, reduced mean arterial and diastolic blood pressure, and reduced carotid intima media thickness, with changes all on par or greater than what is typically observed in sedentary subjects with exercise training. Our results show for the first time that heat therapy has widespread and robust effects on vascular function, and as such, could be a viable treatment option for improving cardiovascular health in a variety of patient populations, particularly those with limited exercise tolerance and/or capabilities.

ABSTRACT

The majority of cardiovascular diseases are characterized by disorders of the arteries, predominantly caused by endothelial dysfunction and arterial stiffening. Intermittent hot water immersion ('heat therapy') results in elevations in core temperature and changes in cardiovascular haemodynamics, such as cardiac output and vascular shear stress, that are similar to exercise, and thus may provide an alternative means of improving health which could be utilized by patients with low exercise tolerance and/or capabilities. We sought to comprehensively assess the effects of 8 weeks of heat therapy on biomarkers of vascular function in young, sedentary subjects. Twenty young, sedentary subjects were assigned to participate in 8 weeks (4-5 times per week) of heat therapy (n = 10; immersion in a 40.5°C bath sufficient to maintain rectal temperature ≥ 38.5°C for 60 min per session) or thermoneutral water immersion (n = 10; sham). Eight weeks of heat therapy increased flow-mediated dilatation from 5.6 ± 0.3 to 10.9 ± 1.0% (P < 0.01) and superficial femoral dynamic arterial compliance from 0.06 ± 0.01 to 0.09 ±0.01 mm(2)  mmHg(-1) (P = 0.03), and reduced (i.e. improved) aortic pulse wave velocity from 7.1 ± 0.3 to 6.1 ± 0.3 m s(-1) (P = 0.03), carotid intima media thickness from 0.43 ± 0.01 to 0.37 ± 0.01 mm (P < 0.001), and mean arterial blood pressure from 83 ± 1 to 78 ± 2 mmHg (P = 0.02). No changes were observed in the sham group or for carotid arterial compliance, superficial femoral intima media thickness or endothelium-independent dilatation. Heat therapy improved endothelium-dependent dilatation, arterial stiffness, intima media thickness and blood pressure, indicating improved cardiovascular health. These data suggest heat therapy may provide a simple and effective tool for improving cardiovascular health in various populations.

Rapid Aspirin Challenge in Patients with Aspirin Allergy and Acute Coronary Syndromes

Aspirin allergy in a patient with acute coronary syndrome represents one of the more urgent challenges an allergist may face. Adverse reactions to aspirin are reported in 1.5% of patients with coronary artery disease. A history of adverse reaction to aspirin often leads to unnecessary withholding of this medication or use of alternative antiplatelet therapy which may be inferior or more costly. Aspirin therapy has been shown to reduce morbidity and mortality in patients with coronary artery disease. Rapid aspirin challenge/desensitization in the aspirin allergic patient has been consistently shown to be both safe and successful in patients with acute coronary syndromes.

Impact of Disease Duration on Vascular Surrogates of Early Atherosclerosis in Childhood-Onset Systemic Lupus Erythematosus

OBJECTIVE

To determine whether longer disease duration negatively impacts carotid intima-media thickness (CIMT), flow-mediated dilation (FMD), and pulse wave velocity (PWV) in a cohort of patients with childhood-onset systemic lupus erythematosus (SLE), and to compare CIMT, FMD, and PWV in patients with childhood-onset SLE with those in healthy children and explore determinants of vascular test results in childhood-onset SLE.

METHODS

Cross-sectional analysis was performed in a prospective longitudinal cohort of patients with childhood-onset SLE at the latest followup visit. Clinical and laboratory data were collected for patients with childhood-onset SLE. CIMT, FMD, and PWV were measured using standardized protocols in patients with childhood-onset SLE and healthy children. Correlations between disease duration and results of the 3 vascular tests were performed. Vascular data in patients with childhood-onset SLE were compared with those in healthy children. Multivariable linear regression was used to identify determinants of CIMT, FMD, and PWV in childhood-onset SLE.

RESULTS

Patients with childhood-onset SLE (n = 149) and healthy controls (n = 178) were enrolled. The median age of the patients was 17.2 years (interquartile range [IQR] 15.7-17.9 years), and their median disease duration was 3.2 years (IQR 1.8-4.9 years). The median age of the healthy children was 14.7 years (IQR 13.1-15.9 years). Longer disease duration correlated with worse FMD (r = -0.2, P = 0.031) in patients with childhood-onset SLE. Patients with childhood-onset SLE had smaller (better) CIMT, higher (better) FMD, and similar PWV compared with healthy controls. Linear regression analysis explained <24% of the variation in vascular test results in patients with childhood-onset SLE, suggesting that other variables should be explored as important determinants of CIMT, FMD, and PWV.

CONCLUSION

In this cohort of 149 patients with childhood-onset SLE, patients did not have worse CIMT, FMD, or PWV than did healthy controls. Longer disease duration was associated with worse FMD, suggesting progressive endothelial dysfunction over time.

Physiological levels of thrombospondin-1 decrease NO-dependent vasodilation in coronary microvessels from aged rats

Aging and cardiovascular disease are associated with the loss of nitric oxide (NO) signaling and a decline in the ability to increase coronary blood flow reserve (CFR). Thrombospondin-1 (Thbs-1), through binding of CD47, has been shown to limit NO-dependent vasodilation in peripheral vascular beds via formation of superoxide (O2 (-)). The present study tests the hypothesis that, similar to the peripheral vasculature, blocking CD47 will improve NO-mediated vasoreactivity in coronary arterioles from aged individuals, resulting in improved CFR. Isolated coronary arterioles from young (4 mo) or old (24 mo) female Fischer 344 rats were challenged with the NO donor, DEA-NONO-ate (1 × 10(-7) to 1 × 10(-4) M), and vessel relaxation and O2 (-) production was measured before and after Thbs-1, αCD47, and/or Tempol and catalase exposure. In vivo CFR was determined in anesthetized rats (1-3% isoflurane-balance O2) via injected microspheres following control IgG or αCD47 treatment (45 min). Isolated coronary arterioles from young and old rats relax similarly to exogenous NO, but addition of 2.2 nM Thbs-1 inhibited NO-mediated vasodilation by 24% in old rats, whereas young vessels were unaffected. Thbs-1 increased O2 (-) production in coronary arterioles from rats of both ages, but this was exaggerated in old rats. The addition of CD47 blocking antibody completely restored NO-dependent vasodilation in isolated arterioles from aged rats and attenuated O2 (-) production. Furthermore, αCD47 treatment increased CFR from 9.6 ± 9.3 (IgG) to 84.0 ± 23% in the left ventricle in intact, aged animals. These findings suggest that the influence of Thbs-1 and CD47 on coronary perfusion increases with aging and may be therapeutically targeted to reverse coronary microvascular dysfunction.

Large high-density lipoprotein particle number is independently associated with microvascular function in patients with well-controlled low-density lipoprotein concentration: A vasodilator stress magnetic resonance perfusion study

BACKGROUND

Abnormalities in total cholesterol, high-density lipoprotein, low-density lipoprotein, and triglycerides are associated with microvascular dysfunction. Recent studies suggest that lipid subfractions better predict atherogenic burden than a routine lipid panel. We sought to determine, whether lipid subfractions are more strongly associated with microvascular function and subclinical atherosclerosis, than conventional lipid measurements using vasodilator stress cardiovascular magnetic resonance (CMR).

METHODS

Twenty-four adults referred for risk stratification from a lipid clinic with low-density lipoprotein cholesterol (LDL-C) <100 mg/dL underwent vasodilator CMR. Time-intensity curves generated from stress and rest perfusion images were used to determine the area under the curve (AUC) for the mid-ventricular slice myocardium and the left ventricular (LV) cavity. Myocardial perfusion reserve index (MPRi) was defined as stress to rest ratio of mid-ventricular myocardium AUC, normalized to LV cavity AUC. Lipid panels that included subfractions of LDL and high-density lipoprotein (HDL) were measured using nuclear magnetic resonance testing. The association between MPRi and lipid parameters was examined using univariate linear regression; lipid components statistically correlated with MPRi (P < .05) were then subjected to multivariate analysis.

RESULTS

Univariate regression analysis showed MPRi was associated with HDL-C, triglycerides, large HDL-P, and small LDL-P; no association was found between MPRi and total cholesterol, LDL-C, total LDL-P, or total HDL-P. Using multivariate analysis, large HDL-P was independently associated with MPRi.

CONCLUSIONS

In patients with LDL-C <100 mg/dL, large HDL-P is independently associated with CMR-derived myocardial perfusion reserve, a surrogate for microvascular function and subclinical atherosclerosis. Further studies using lipid subfractions to better understand cardiovascular risks are warranted.

Abnormal phosphorylation of Tie2/Akt/eNOS signaling pathway and decreased number or function of circulating endothelial progenitor cells in prehypertensive premenopausal women with diabetes mellitus

BACKGROUNDS

The number and activity of circulating endothelial progenitor cells (EPCs) in prehypertension is preserved in premenopausal women. However, whether this favorable effect still exists in prehypertensive premenopausal women with diabetes is not clear.

METHODS

This study compared the number and functional activity of circulating EPCs in normotensive or prehypertensive premenopausal women without diabetes mellitus and normotensive or prehypertensive premenopausal women with diabetes mellitus, evaluated the vascular endothelial function in each groups, and investigated the possible underlying mechanism.

RESULTS

We found that compared with normotensive premenopausal women, the number and function of circulating EPCs, as well as endothelial function evaluated by flow-mediated dilatation (FMD) in prehypertensive premenopausal women were preserved. In parallel, the Tie2/Akt/eNOS signaling pathway and the plasma NO level or NO secretion of circulating EPCs in prehypertensive premenopausal women was also retained. However, in presence of normotension or prehypertension with diabetes mellitus, the number or function of circulating EPCs and FMD in premenopausal women decreased. Similarly, the phosphorylation of Tie2/Akt/eNOS signaling pathway and the plasma NO level or NO secretion of circulating EPCs was reduced in prehypertension premenopausal with diabetes mellitus.

CONCLUSION

The present findings firstly demonstrate that the unfavorable effects of diabetes mellitus on number and activity of circulating EPCs in prehypertension premenopausal women, which is at least partially related to the abnormal phosphorylation of Tie2/Akt/eNOS signaling pathway and subsequently reduced nitric oxide bioavailability. The Tie2/Akt/eNOS signaling pathway may be a potential target of vascular protection in prehypertensive premenopausal women with diabetes mellitus.

Microvascular Dilator Function in Athletes: A Systematic Review and Meta-analysis

PURPOSE

Despite the growing research interest in vascular adaptations to exercise training over the last few decades, it remains unclear whether microvascular function in healthy subjects can be further improved by regular training. Herein, we sought to systematically review the literature and determine whether microvascular dilator function is greater in athletes compared to age-matched healthy untrained subjects.

METHODS

We conducted a systematic search of MEDLINE, Cochrane, EMBASE, and Web of Science since their inceptions until October 2013 for articles evaluating indices of primarily microvascular endothelium-dependent or endothelium-independent dilation (MVEDD and MVEID, respectively) in athletes. A meta-analysis was performed to determine the standardized mean difference (SMD) in MVEDD and MVEID between athletes and age-matched controls. Subgroup analyses were used to study potential moderating factors.

RESULTS

Thirty-six studies were selected after systematic review, comprising 521 athletes (506 endurance-trained and 15 endurance- and strength-trained) and 496 age-matched control subjects. After data pooling, athletes presented higher MVEDD (31 studies; SMD, 0.47; P < 0.00001) and MVEID (14 studies; SMD, 0.51; P < 0.00001) compared with the control subjects. Similar results were observed in young (younger than 40 yr) and master (older than 55 yr) athletes when analyzed separately.

CONCLUSION

Both young and master athletes present enhanced microvascular function compared with age-matched untrained but otherwise healthy subjects. These data provide evidence of a positive association between exercise training and microvascular function in the absence of known underlying cardiovascular disease.

Intravenous Lipid Infusion Induces Endoplasmic Reticulum Stress in Endothelial Cells and Blood Mononuclear Cells of Healthy Adults

BACKGROUND

Endoplasmic reticulum (ER) stress and the subsequent unfolded protein response may initially be protective, but when prolonged, have been implicated in atherogenesis in diabetic conditions. Triglycerides and free fatty acids (FFAs) are elevated in patients with diabetes and may contribute to ER stress. We sought to evaluate the effect of acute FFA elevation on ER stress in endothelial and circulating white cells.

METHODS AND RESULTS

Twenty-one healthy subjects were treated with intralipid (20%; 45 mL/h) plus heparin (12 U/kg/h) infusion for 5 hours. Along with increased triglyceride and FFA levels, intralipid/heparin infusion reduced the calf reactive hyperemic response without a change in conduit artery flow-mediated dilation consistent with microvascular dysfunction. To investigate the short-term effects of elevated triglycerides and FFA, we measured markers of ER stress in peripheral blood mononuclear cells (PBMCs) and vascular endothelial cells (VECs). In VECs, activating transcription factor 6 (ATF6) and phospho-inositol requiring kinase 1 (pIRE1) proteins were elevated after infusion (both P<0.05). In PBMCs, ATF6 and spliced X-box-binding protein 1 (XBP-1) gene expression increased by 2.0- and 2.5-fold, respectively (both P<0.05), whereas CHOP and GADD34 decreased by ≈67% and 74%, respectively (both P<0.01). ATF6 and pIRE1 protein levels also increased (both P<0.05), and confocal microscopy revealed the nuclear localization of ATF6 after infusion, suggesting activation.

CONCLUSIONS

Along with microvascular dysfunction, intralipid infusion induced an early protective ER stress response evidenced by activation of ATF6 and IRE1 in both leukocytes and endothelial cells. Our results suggest a potential link between metabolic disturbances and ER stress that may be relevant to vascular disease.

Endothelial dysfunction and coronary artery disease: a state of the art review

Atherosclerotic coronary artery disease (CAD) is a major cause of morbidity and mortality in the developed world. Endothelial dysfunction plays an important role in the development of atherosclerosis and predicts cardiovascular (CV) outcomes independent of conventional CV risk factors. In recent years, there have been tremendous improvements in the pharmacological prevention and management of CAD. In this review, the pathophysiology of endothelial dysfunction in relation to CAD is discussed and various techniques of invasive and noninvasive assessments of peripheral and coronary endothelial function described. In addition, evidence for the association of endothelial dysfunction and CV outcomes has been examined and finally the role of therapeutic interventions in endothelial dysfunction has been discussed.

Coronary endothelial dysfunction in non-obstructive coronary artery disease: Risk, pathogenesis, diagnosis and therapy

Up to half of patients with signs and symptoms of stable ischemic heart disease have non-obstructive coronary artery disease (NoCAD). Recent evidence demonstrates that two-thirds of patients with NoCAD have demonstrable coronary endothelial dysfunction represented by microvascular or diffuse epicardial spasm following acetylcholine challenge. Patients with coronary endothelial dysfunction are recognized to have significant health services use and morbidity as well as increased risk of developing flow-limiting coronary artery disease and myocardial events, including death. Currently, there are few centers that test for this etiology owing to lack of knowledge, limited evidence for treatment options and invasive diagnostic strategies. This article reviews the pathophysiology, epidemiology, diagnosis and treatment of coronary endothelial dysfunction as a subgroup of NoCAD.

Subclinical atherosclerotic risk in endurance-trained premenopausal amenorrheic women

PURPOSE

In premenopausal women, amenorrhea contributes to endothelial dysfunction. It is unknown whether this vascular functional change is associated with vascular structural change.

METHODS

This study examined regional and systemic vascular structure and function to gain insight into subclinical atherosclerotic risk in 10 amenorrheic athletes, 18 eumenorrheic athletes, and 15 recreationally active controls. Brachial flow-mediated dilation (FMD) and low flow mediated constriction (L-FMC) were used to measure global endothelial function. Carotid-femoral pulse wave velocity (PWV) was used to measure aortic stiffness. Doppler-ultrasound of the superficial femoral artery (SFA) was used to assess intima-media thickness (IMT) and vessel diameter as indicators of vascular remodeling.

RESULTS

Amenorrheic athletes had significantly lower brachial FMD adjusted for shear stimulus (6.9 ± 1.3%) compared with eumenorrheic athletes (11.0 ± 1.0%) and controls (11.0 ± 1.1%, p = 0.05). Brachial L-FMC (-1.8 ± 4.3%) and aortic PWV (5.0 ± 1.0 m/s) of amenorrheic athletes were similar to those of eumenorrheic athletes (L-FMC, -1.6 ± 4.6%; PWV, 4.6 ± 0.5 m/s) and controls (L-FMC, -1.5 ± 2.8%, p = 0.98; PWV, 5.4 ± 0.7 m/s, p = 0.15). SFA diameters were similar in amenorrheic athletes (5.7 ± 0.7 mm) and eumenorrheic athletes (5.7 ± 0.7 mm), but amenorrheic athletes had larger SFA diameters compared with controls (5.1 ± 0.6 mm, p = 0.04). In amenorrheic athletes, SFA IMT (0.31 ± 0.03 mm) was similar to that of eumenorrheic athletes (0.35 ± 0.07 mm) but significantly thinner compared to that of controls (0.38 ± 0.06, p = 0.01).

CONCLUSION

Vascular dysfunction in female amenorrheic athletes is not systemic. Parenthetically, amenorrhea may not prevent favorable peripheral vascular structural adaptations to habitual exercise training.

Prognostic Value of Flow-Mediated Vasodilation in Brachial Artery and Fingertip Artery for Cardiovascular Events: A Systematic Review and Meta-Analysis

BACKGROUND

Endothelial dysfunction plays a pivotal role in cardiovascular disease progression, and is associated with adverse events. The purpose of this systematic review and meta-analysis was to investigate the prognostic magnitude of noninvasive peripheral endothelial function tests, brachial artery flow-mediated dilation (FMD), and reactive hyperemia--peripheral arterial tonometry (RH-PAT) for future cardiovascular events.

METHODS AND RESULTS

Databases of MEDLINE, EMBASE, and the Cochrane Library were systematically searched. Clinical studies reporting the predictive value of FMD or RH-PAT for cardiovascular events were identified. Two authors selected studies and extracted data independently. Pooled effects were calculated as risk ratio (RR) for continuous value of FMD and natural logarithm of RH-PAT index (Ln_RHI) using random-effects models. Thirty-five FMD studies of 17 280 participants and 6 RH-PAT studies of 1602 participants were included in the meta-analysis. Both endothelial function tests significantly predicted cardiovascular events (adjusted relative risk [95% CI]: 1% increase in FMD 0.88 [0.84-0.91], P<0.001, 0.1 increase in Ln_RHI 0.79 [0.71-0.87], P<0.001). There was significant heterogeneity in the magnitude of the association across studies. The magnitude of the prognostic value in cardiovascular disease subjects was comparable between these 2 methods; a 1 SD worsening in endothelial function was associated with doubled cardiovascular risk.

CONCLUSIONS

Noninvasive peripheral endothelial function tests, FMD and RH-PAT, significantly predicted cardiovascular events, with similar prognostic magnitude. Further research is required to determine whether the prognostic values of these 2 methods are independent of each other and whether an endothelial function-guided strategy can provide benefit in improving cardiovascular outcomes.

Visceral adiposopathy: a vascular perspective

Obesity has emerged as one of the most critical health care problems globally that is associated with the development of insulin resistance, type 2 diabetes mellitus, metabolic dysfunction and cardiovascular disease. Central adiposity with intra-abdominal deposition of visceral fat, in particular, has been closely linked to cardiometabolic consequences of obesity. Increasing epidemiological, clinical and experimental data suggest that both adipose tissue quantity and perturbations in its quality termed "adiposopathy" contribute to mechanisms of cardiometabolic disease. The current review discusses regional differences in adipose tissue characteristics and highlights profound abnormalities in vascular endothelial function and angiogenesis that are manifest within the visceral adipose tissue milieu of obese individuals. Clinical data demonstrate up-regulation of pro-inflammatory and pro-atherosclerotic mediators in dysfunctional adipose tissue that may support pathological vascular changes not only locally in fat but also in multiple organ systems, including coronary and peripheral circulations, potentially contributing to mechanisms of obesity-related cardiovascular disease.

Carotid Intima-Media Thickness for Atherosclerosis

The carotid intima-media thickness (IMT) is a widely used surrogate marker for atherosclerosis worldwide. The carotid IMT can be simply, noninvasively, and reproducibly measured through B-mode carotid ultrasound. The carotid IMT is also a strong predictor of future cerebral and cardiovascular events. In addition, regressions of increased carotid IMT by lipid-lowering and antihypertensive drugs have been reported. Despite the strong association between increased carotid IMT and cardiovascular disease, it remains unclear whether routine carotid IMT measurement is useful for the detection of subclinical atherosclerosis in clinical practice. Researches should consider other methodological aspects, such as the definition of carotid plaques, the choice of measurement sites on the common or internal carotid artery, and the assessment of maximum or minimum IMT. The detailed guidelines for measuring carotid IMT vary by county. Thus, the usefulness of the carotid IMT may be assessed in different countries taking racial differences into account. Other important parameters revealed by carotid ultrasound, such as artery stenosis and the characteristics and size of plaques, should also be considered. Physicians should comprehensively interpret the results of carotid ultrasonography. Therefore, carotid ultrasonography is an essential tool for assessing cardiovascular risk in clinical settings.

Association of Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) With Cardiovascular Risk in Primary Prevention

OBJECTIVE

Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays an important role in the modulation of low-density lipoprotein metabolism. This study was conducted to evaluate the relationship between serum PCSK9 concentrations and measures of vascular health, subclinical atherosclerosis, and adverse cardiovascular events. The relationship between traditional risk factors and PCSK9 concentrations was also examined.

APPROACH AND RESULTS

The cohort consisted of 1527 middle-aged men enrolled in the Firefighters and Their Endothelium (FATE) study, who were free of vascular disease and followed up over a mean period of 7.2±1.7 years. Baseline evaluation included assessment of traditional cardiovascular risk factors and measurements of flow-mediated dilation, reactive hyperemic velocity time integral, and carotid intima-media thickness. Biochemical parameters, including serum PCSK9 concentrations, were analyzed to determine predictors of vascular measures and to evaluate the role of PCSK9 in the occurrence of adverse cardiovascular events. Multivariate linear regression analyses indicated that body mass index, insulin, low-density lipoprotein-cholesterol, and triglycerides were independent predictors of PCSK9. Further modeling revealed no correlation between PCSK9 concentration and carotid intima media thickness, flow-mediated dilation, or reactive hyperemic velocity time integral. Analyses indicated no significant association between PCSK9 concentrations and cardiovascular event occurrences.

CONCLUSIONS

Although correlated with low-density lipoprotein-cholesterol, insulin, and triglycerides, PCSK9 was not associated with measures of vascular function or structure. There was also no significant relationship between PCSK9 concentrations and cardiovascular events. Thus, although PCSK9 is an important therapeutic target to reduce circulating low-density lipoprotein-cholesterol concentrations, it is unlikely to be a biomarker of atherosclerotic risk or vascular health.

Cardiovascular Imaging for the Primary Prevention of Atherosclerotic Cardiovascular Disease Events

Traditional cardiovascular risk factors have well-known limitations for the accurate assessment of individual cardiovascular risk. Unlike risk factor-based scores which rely on probabilistic calculations derived from population-based studies, coronary artery calcium (CAC) scoring, and carotid ultrasound allow for the direct visualization and quantification of subclinical atherosclerosis with the potential for a more accurate, personalized risk assessment and treatment approach. Among strategies used to guide preventive management, CAC scoring has consistently and convincingly outperformed traditional risk factors for the prediction of adverse cardiovascular events. Moreover, several studies have demonstrated the potential of CAC testing to improve precision for the use of more intensive pharmacologic therapies, such as aspirin and statins, in patients most likely to derive benefit, as compared to atherosclerotic cardiovascular disease risk calculators. By comparison to CAC, the role of carotid ultrasound for the measurement of carotid intima-media thickness (CIMT) remains less well-elucidated but may be significantly improved with the inclusion of plaque screening and novel three-dimensional measurements of plaque volume and morphology. Despite significant evidence supporting the ability of non-invasive atherosclerosis imaging (particularly CAC) to guide preventive management, imaging remains an under-utilized strategy among current guidelines and clinical practice. Herein, we review evidence regarding CAC and carotid ultrasound for patient risk classification, with a comparison of these techniques to currently advocated traditional risk factor-based scores.

Race/Ethnic Differences in the Associations of the Framingham Risk Factors with Carotid IMT and Cardiovascular Events

Background

Clinical manifestations and outcomes of atherosclerotic disease differ between ethnic groups. In addition, the prevalence of risk factors is substantially different. Primary prevention programs are based on data derived from almost exclusively White people. We investigated how race/ethnic differences modify the associations of established risk factors with atherosclerosis and cardiovascular events.

Methods

We used data from an ongoing individual participant meta-analysis involving 17 population-based cohorts worldwide. We selected 60,211 participants without cardiovascular disease at baseline with available data on ethnicity (White, Black, Asian or Hispanic). We generated a multivariable linear regression model containing risk factors and ethnicity predicting mean common carotid intima-media thickness (CIMT) and a multivariable Cox regression model predicting myocardial infarction or stroke. For each risk factor we assessed how the association with the preclinical and clinical measures of cardiovascular atherosclerotic disease was affected by ethnicity.

Results

Ethnicity appeared to significantly modify the associations between risk factors and CIMT and cardiovascular events. The association between age and CIMT was weaker in Blacks and Hispanics. Systolic blood pressure associated more strongly with CIMT in Asians. HDL cholesterol and smoking associated less with CIMT in Blacks. Furthermore, the association of age and total cholesterol levels with the occurrence of cardiovascular events differed between Blacks and Whites.

Conclusion

The magnitude of associations between risk factors and the presence of atherosclerotic disease differs between race/ethnic groups. These subtle, yet significant differences provide insight in the etiology of cardiovascular disease among race/ethnic groups. These insights aid the race/ethnic-specific implementation of primary prevention.

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.

Impact of prolonged sitting on lower and upper limb micro- and macrovascular dilator function

NEW FINDINGS

What is the central question of this study? The prevalence of sedentary behaviour in the workplace and increased daily sitting time have been associated with the development of cardiovascular disease; however, studies investigating the impact of sitting on vascular function remain limited. What is the main finding and its importance? We demonstrate that there is a marked vulnerability of the vasculature in the lower and upper limbs to prolonged sitting and highlight the importance of physical activity in restoring vascular function in a limb-specific manner. Sedentary behaviour in the workplace and increased daily sitting time are on the rise; however, studies investigating the impact of sitting on vascular function remain limited. Herein, we hypothesized that 6 h of uninterrupted sitting would impair limb micro- and macrovascular dilator function and that this impairment could be improved with a bout of walking. Resting blood flow, reactive hyperaemia to 5 min cuff occlusion (microvascular reactivity) and associated flow-mediated dilatation (FMD; macrovascular reactivity) were assessed in popliteal and brachial arteries of young men at baseline (Pre Sit) and after 6 h of uninterrupted sitting (Post Sit). Measures were then repeated after a 10 min walk (~1000 steps). Sitting resulted in a marked reduction of resting popliteal artery mean blood flow and mean shear rate (6 h mean shear rate, -52 ± 8 s(-1) versus Pre Sit, P < 0.05). Interestingly, reductions were also found in the brachial artery (6 h mean shear rate, -169 ± 41 s(-1) versus Pre Sit, P < 0.05). Likewise, after 6 h of sitting, cuff-induced reactive hyperaemia was reduced in both the lower leg (-43 ± 7% versus Pre Sit, P < 0.05) and forearm (-31 ± 11% versus Pre Sit, P < 0.05). In contrast, popliteal but not brachial artery FMD was blunted with sitting. Notably, lower leg reactive hyperaemia and FMD were restored after walking. Collectively, these data suggest that prolonged sitting markedly reduces lower leg micro- and macrovascular dilator function, but these impairments can be fully normalized with a short bout of walking. In contrast, upper arm microvascular reactivity is selectively impaired with prolonged sitting, and walking does not influence this effect.