Clinical Assessment Of Endothelial Function Research Articles

SGLT2 inhibitor ameliorates endothelial dysfunction associated with the common ALDH2 alcohol flushing variant.

The common aldehyde dehydrogenase 2 (ALDH2) alcohol flushing variant known as ALDH2*2 affects ∼8% of the world's population. Even in heterozygous carriers, this missense variant leads to a severe loss of ALDH2 enzymatic activity and has been linked to an increased risk of coronary artery disease (CAD). Endothelial cell (EC) dysfunction plays a determining role in all stages of CAD pathogenesis, including early-onset CAD. However, the contribution of ALDH2*2 to EC dysfunction and its relation to CAD are not fully understood. In a large genome-wide association study (GWAS) from Biobank Japan, ALDH2*2 was found to be one of the strongest single-nucleotide polymorphisms associated with CAD. Clinical assessment of endothelial function showed that human participants carrying ALDH2*2 exhibited impaired vasodilation after light alcohol drinking. Using human induced pluripotent stem cell-derived ECs (iPSC-ECs) and CRISPR-Cas9-corrected ALDH2*2 iPSC-ECs, we modeled ALDH2*2-induced EC dysfunction in vitro, demonstrating an increase in oxidative stress and inflammatory markers and a decrease in nitric oxide (NO) production and tube formation capacity, which was further exacerbated by ethanol exposure. We subsequently found that sodium-glucose cotransporter 2 inhibitors (SGLT2i) such as empagliflozin mitigated ALDH2*2-associated EC dysfunction. Studies in ALDH2*2 knock-in mice further demonstrated that empagliflozin attenuated ALDH2*2-mediated vascular dysfunction in vivo. Mechanistically, empagliflozin inhibited Na+/H+-exchanger 1 (NHE-1) and activated AKT kinase and endothelial NO synthase (eNOS) pathways to ameliorate ALDH2*2-induced EC dysfunction. Together, our results suggest that ALDH2*2 induces EC dysfunction and that SGLT2i may potentially be used as a preventative measure against CAD for ALDH2*2 carriers.

Clinical Assessment of Endothelial Function in Convalescent COVID-19 Patients Undergoing Multidisciplinary Pulmonary Rehabilitation.

Background: Growing evidence points to a key role of endothelial dysfunction in the pathogenesis of COVID-19. In this study, we evaluated changes in endothelium-dependent flow-mediated dilation (FMD) in a cohort of convalescent COVID-19 patients undergoing pulmonary rehabilitation (PR). Methods: After swab test negativization, convalescent COVID-19 patients referring to a post-acute care facility for PR were consecutively screened for inclusion. Study procedures were performed at the time of hospitalization and discharge. Results: We enrolled 82 convalescent COVID-19 patients (85.4% males, mean age 60.4 years). After PR, a significant improvement in most pulmonary function tests and exercise capacity was documented. FMD changed from 2.48% ± 2.01 to 4.24% ± 2.81 (p < 0.001), corresponding to a 70.9% increase. Significantly higher changes in FMD were found in patients without a history of vascular events as compared to those with (+2.04% ± 2.30 vs. +0.61% ± 1.83, p = 0.013). Values of forced expiratory volume in 1 s (FEV1%), forced vital capacity (FVC%) and diffusion capacity for carbon monoxide (DLCO%) significantly and directly correlated with FMD both at baseline and after PR. Patients with normal FEV1% (≥80% predicted) during the overall study period or those normalizing FEV1% after PR showed a more significant FMD change as compared to patients with persistently impaired FEV1% (<80% predicted) (p for trend = 0.029). This finding was confirmed in a multivariate analysis. Conclusions: Clinically evaluated endothelial function improves after PR in convalescent COVID-19 patients. A direct and persistent association between the severity of pulmonary and vascular disease can be hypothesized. Endothelial function testing may be useful in the follow-up of convalescent COVID-19 patients.

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

Endothelial dysfunction is a key mechanism in the development of cardiac remodelling and diastolic dysfunction in heart failure with preserved ejection fraction (HFpEF). Flow-mediated (FMD) and nitrate-mediated dilation (NMD) are noninvasive methods to assess endothelial function. We performed a meta-analysis evaluating the impact of HFpEF on FMD and NMD. PubMed, Web of Science, Scopus and EMBASE databases were systematically searched according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Differences were expressed as mean difference (MD) with 95% confidence intervals (95%CI). The random effects method was used. A total of seven studies were included in the final analysis, 7 with data on FMD (326 HFpEF patients and 417 controls) and 3 on NMD (185 HFpEF patients and 271 controls). Compared to controls, HFpEF patients showed significantly lower FMD (MD: -1.929; 95%CI: -2.770, -1.088; P<.0001) and NMD values (MD: -2.795; 95%CI: -3.876, -1.715; P<.0001). Sensitivity analyses substantially confirmed results. Meta-regression models showed that increasing differences in E/A ratio (Z-score: -2.002; P=.045), E/E' ratio (Z-score: -2.181; P=.029) and left atrial diameter (Z-score: -1.951; P=.050) were linked to higher differences in FMD values between cases and controls. Impaired endothelial function can be documented in HFpEF, with the possibility of a direct association between the severity of diastolic and endothelial dysfunction. Targeting endothelial dysfunction through pharmacological and rehabilitation strategies may represent an attractive therapeutic option.

Deciphering Endothelial Dysfunction in the HIV-Infected Population.

Cardiovascular disease (CVD), as a possible consequence of endothelial dysfunction, is prevalent among HIV-infected patients despite successful administration of antiretroviral drugs. This warrants the routine clinical assessment of endothelial function in HIV-positive patients to circumvent potential CVD events. Several different non-invasive strategies have been employed to assess endothelial function in clinical research studies yielding inconsistencies among these reports. This review summarises the different techniques used for assessing endothelial function, with a focus on proposed blood-based biomarkers, such as endothelial leukocyte adhesion molecule-1 (E-selectin), soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), von Willebrand factor (vWF), TNF-α, interleukin 6 (IL6) and soluble thrombomodulin (sTM). The identification of suitable blood-based biomarkers, especially those that can be measured using a point-of-care device, would be more applicable in under-resourced countries where the prevalence of HIV is high.

Clinical assessment of endothelial function in patients with chronic obstructive pulmonary disease: a systematic review with meta-analysis.

Patients with chronic obstructive pulmonary disease (COPD) have an increased cardiovascular morbidity and mortality. Flow-mediated (FMD) and nitrate-mediated dilatation (NMD) are considered non-invasive methods to assess endothelial function and surrogate markers of subclinical atherosclerosis. We performed a systematic review with meta-analysis and meta-regression to evaluate the impact of COPD on FMD and NMD. Studies were systematically searched in the PubMed, Web of Science, Scopus and EMBASE databases. The random-effect method was used to take into account the variability among included studies. A total of eight studies were included in the final analysis, eight with data on FMD (334 COPD patients) and two on NMD (104 COPD patients). Compared to controls, COPD patients show a significantly lower FMD (MD -3.15%; 95% CI -4.89, -1.40; P<0.001) and NMD (MD -3.53%; 95% CI -7.04, -0.02; P=0.049). Sensitivity analyses substantially confirms the results. Meta-regression models show that a more severe degree of airway obstruction is associated with a more severe FMD impairment in COPD patients than in controls. Regression analyses confirm that the association between COPD and endothelial dysfunction is independent of baseline smoking status and most traditional cardiovascular risk factors. In conclusion, COPD is significantly and independently associated with endothelial dysfunction. These findings may be useful to plan adequate cardiovascular prevention strategies in this clinical setting, with particular regard to patients with a more severe disease.

Clinical assessment of endothelial function in patients with rheumatoid arthritis: A meta-analysis of literature studies

BackgroundSeveral studies reported an increased cardiovascular (CV) morbidity and mortality in patients with rheumatoid arthritis (RA). Flow-mediated (FMD) and nitrate-mediated dilation (NMD) are considered non-invasive methods to assess endothelial function and surrogate markers of subclinical atherosclerosis. MethodsWe performed a systematic review with meta-analysis and meta-regression of literature studies evaluating the impact of RA on FMD and NMD. Studies evaluating the relationship between RA and markers of CV risk (FMD and NMD) were systematically searched in the PubMed, Web of Science, Scopus and EMBASE databases. The random-effect method was used for analyses and results were expressed as mean difference (MD). ResultsA total of 20 studies (852 RA patients, 836 controls) were included in the final analysis. In detail, 20 studies with data on FMD (852 cases, 836 controls) and 5 studies with data on NMD (207 cases, 147 controls) were analyzed. Compared to controls, RA patients showed a significantly lower FMD (MD: −2.16%; 95% CI: −3.33, −0.98; P=0.0003), with no differences in NMD (MD: −0.41%; 95% CI: −2.89, 2.06; P=0.74). Interestingly, a lower FMD (MD: −2.00%; 95% CI: −3.20, −0.80; P=0.001) and no differences in NMD (P=0.49) were confirmed when excluding data on patients with early-RA. Meta-regression models showed that a more severe inflammatory status was associated with a more significant impairment in FMD. ConclusionsRA patients show impaired FMD, which is currently considered an independent predictor of CV events. The presence of endothelial dysfunction in RA should be taken into account to plan adequate prevention strategies and therapeutic approaches.

Hypertension and Endothelial Dysfunction: Therapeutic Approach

A large body of evidence indicates that patients with essential hypertension are characterized by endothelial dysfunction mediated by an impaired NO availability secondary to oxidative stress production. A dysfunctioning endothelium is an early marker of the development of atherosclerotic changes and can also contribute to cardiovascular events. Vascular reactivity tests represent the most widely used methods in the clinical assessment of endothelial function. In the last two decades, many studies have evaluated the endothelium in hypertensive patients, using different techniques. Several methodologies were developed to study microcirculation (resistance arteries and arterioles) and macrocirculation (conduit arteries), both in coronary and peripheral vascular districts. This review will describe the most relevant available techniques in the research on endothelial dysfunction in essential hypertension, their advantages and limitations, focusing on available data on endothelial dysfunction and on the effect of treatment. Endothelial dysfunction in the coronary and peripheral circulation of hypertensive patients are associated with hypertensive target organ damage and it is predictive of cardiovascular events. Several non-pharmacological approaches, including physical exercise and dietary interventions, can ameliorate endothelial function in hypertensive patients. Despite blood pressure reduction per se is not effective, some antihypertensive drugs can improve endothelial dysfunction, particularly calcium channel antagonist in the microcirculation, ACE-inhibitors and AT1-receptor antagonists mostly in conduit arteries. Some beneficial effects were also exerted by nebivolol and statins. Future studies are needed to confirm whether the improvement in endothelial dysfunction is associated to better cardiovascular prognosis in hypertension.

How to Evaluate Microvascular Organ Damage in Hypertension

Patients with essential hypertension are characterized by endothelial dysfunction and impaired nitric oxide availability secondary to oxidative stress production. A dysfunctioning endothelium is an early marker of the development of atherosclerotic changes and can also contribute to cardiovascular events. The autocrine/paracrine activity of endothelial cells makes it very difficult to investigate endothelial function in clinical research. Vascular reactivity tests represent the most widely used methods of clinical assessment of endothelial function. The aim of these tests is to activate or block endothelial cell function while measuring consequent changes in vascular tone in selected vascular districts. Many studies have evaluated the endothelium in hypertensive patients, using different techniques. Several methodologies were developed to study microcirculation (resistance arteries and arterioles), both in coronary and peripheral vascular districts. In particular, peripheral microcirculation can be evaluated in functionally isolated vascular districts such as the peripheral muscle (usually forearm), the subcutaneous tissue, or the skin. This article focuses on the most relevant available techniques in the research on endothelial dysfunction in essential hypertension, in particular their advantages and major limitations. The coronary microcirculation can be evaluated by measuring coronary blood flow with Doppler flow wire and quantitative angiography during the intracoronary infusion of endothelial agonists. The isolated and perfused forearm technique is the most often used approach in the assessment of endothelial function in peripheral muscle microcirculation. The subcutaneous small resistance arteries can be studied using the Mulvany myograph device, an in vitro, ex vivo technique. Finally, the use of the laser digital Doppler technique provides a non-invasive approach to the evaluation of the skin microcirculation. Each technique employed to assess endothelial function has specific limitations that hinder its applicability in large-scale screening. In addition, studies assessing the degree of correlation among measures of endothelial function, as evaluated in different vascular beds, have demonstrated a poor relationship and, while statistically significant, the findings are of no clinical relevance. Therefore, no one technique can be considered a surrogate for another. At the present time, the optimal methodology for investigating the multifaceted aspects of endothelial dysfunction is still under debate. Only the growing concordant results from different reproducible and reliable methods exploring endothelial function with different stimuli will support and strengthen experimental findings, thus providing conclusive answers in this area of research.

Non-Invasive Diagnostic Tools for Investigating Endothelial Dysfunction

The endothelium is not merely a barrier but it plays a key role in the maintenance of vascular homeostasis. A dysfunctional endothelium is an early marker of the development of atherosclerotic changes and can also contribute to cardiovascular events. Vascular reactivity tests represent the most widely used methods in the clinical assessment of endothelial function and in the last two decades, several methodologies were developed to study it non invasively in the peripheral macrocirculation (conduit arteries) and microcirculation (resistance arteries and arterioles). This review will centre on the most relevant available non-invasive techniques in the research on endothelial function, their advantages and limitations. Flow mediated dilation (FMD) of the brachial artery by ultrasounds is the most widely used vascular test to assess endothelium-dependent vasodilation. Other approaches include measurement of microcirculatory reactive hyperaemia by forearm venous pletysmography or digital pulse amplitude tonometry, response to beta2 agonist by applanation tonometry or digital photoplethysmography and several test by skin laser doppler. It appears that FMD is the most reproducible test when an appropriate and accurate methodology is applied. Recently, post-ischemic vasodilation in the cavernous arteries was also suggested to study endothelial function in patients with erectile dysfunction. Systemic markers proposed as measures of NO biology, inflammatory cytokines, adhesion molecules, or markers of endothelial damage and repair have only a very limited role as a result of biological and assay availability and variability, these factors currently have a limited role in the assessment of individual patients. The optimal methodology for investigating the multifaceted aspects of endothelial dysfunction is still under debate. Therefore, no available test to assess endothelial function has sufficient sensitivity and specificity to be used yet in clinical practice. Only the growing concordant results from different reproducible and reliable non-invasive methods exploring endothelial function with different stimuli will support and strengthen experimental findings, thus providing conclusive answers in this area of research.

Endothelial Function Assessment in Complicated Hypertension

A large body of evidence indicates that patients with essential hypertension, and even more those with complicated hypertension, are characterized by endothelial dysfunction characterized by impaired NO availability secondary to oxidative stress production. A dysfunctioning endothelium is an early marker of the development of atherosclerotic changes and can also contribute to cardiovascular events. Vascular reactivity tests represent the most widely used methods in the clinical assessment of endothelial function. In the last two decades, many studies have evaluated the endothelium in hypertensive patients, using different techniques. Several methodologies were developed to study microcirculation (resistance arteries and arterioles) and macrocirculation (conduit arteries), both in coronary and peripheral vascular districts. This review will centre on the most relevant available techniques in the research on endothelial dysfunction in essential hypertension, their advantages and limitations, focusing on available data on endothelial dysfunction which characterizes patients with complicated hypertension. No available test to assess endothelial function has sufficient sensitivity and specificity to be used in clinical practice. Therefore, the optimal methodology for investigating the multifaceted aspects of endothelial dysfunction is still under debate. Only the growing concordant results from different reproducible and reliable methods exploring endothelial function with different stimuli will support and strengthen experimental findings, thus providing conclusive answers in this area of research.

Clinical Assessment of Endothelial Function

The endothelium is crucial in the maintenance of normal vascular function and disturbance of this balance is a key early event in the development of vascular disease. A wide range of techniques currently exists for assessment of endothelial function in both the coronary and the peripheral vasculature. Many of these in vivo tests have concentrated on measuring nitric oxide bioavailability, however more recently methods for measuring other vascular parameters, such as tissue-plasminogen activator release, have been used. Furthermore indirect systemic measurements of endothelial function and endothelial progenitor cells have been investigated. These methods have given great insights into the pathophysiology of atherosclerosis and have aided in the development of a number of antiatherosclerotic therapies. Importantly the methods used to date for assessing endothelial function in vivo are accurate, reproducible and correlate with the future risk of cardiovascular events. The development of new techniques and the constant refinement of established techniques suggest that many more insights are to be gained from clinical assessment of endothelial function.

Review: Clinical assessment of endothelial function — an update

Endothelial dysfunction precedes clinically detectable vascular disease, suggesting its early detection may allow the targeting of treatment to improve endothelial function and thus inhibit progression of disease.1,2Although the evidence for a preventive strategy remains circumstantial, there is worldwide interest in the measurement of endothelial function in relation to risk factors and treatment of atherosclerotic vascular disease. Unfortunately, a widely applicable clinical measurement of endothelial function does not yet exist; those that are available remain tools for research. The ideal clinical test of endothelial function should be specific, sensitive and reproducible, as well as simple to perform, painless, and inexpensive. In this review we outline the relative merits and disadvantages of the techniques that are available.

Nitric oxide, atherosclerosis and the clinical relevance of endothelial dysfunction.

The endothelium plays a key role in vascular homeostasis through the release of a variety of autocrine and paracrine substances, the best characterized being nitric oxide. A healthy endothelium acts to prevent atherosclerosis development and its complications through a complex and favorable effect on vasomotion, platelet and leukocyte adhesion and plaque stabilization. The assessment of endothelial function in humans has generally involved the description of vasomotor responses, but more widely includes physiological, biochemical and genetic markers that characterize the interaction of the endothelium with platelets, leukocytes and the coagulation system. Stable markers of inflammation such as high sensitivity C-reactive protein are indirect and potentially useful measures of endothelial function for example. Attenuation of the effect of nitric oxide accounts for the majority of what is described as endothelial dysfunction. This occurs in response to atherosclerosis or its risk factors. Much remains to be learned about the molecular and genetic pathophysiological mechanisms of endothelial cell abnormalities. However, pharmacological intervention with a growing list of medications can favorably modify endothelial function, paralleling beneficial effects on cardiovascular morbidity and mortality. In addition, several small studies have provided tantalizing evidence that measures of endothelial health might provide prognostic information about an individual patient's risk of subsequent events. As such, the sum of this evidence makes the clinical assessment of endothelial function an attractive surrogate marker of atherosclerosis disease activity. The review will focus on the role of nitric oxide in atherosclerosis and the clinical relevance of these findings.

Elimination of Electrically Induced Iontophoretic Artefacts: Implications for Non-Invasive Assessment of Peripheral Microvascular Function

Iontophoretic assessment of skin microvascular function is complicated by the occurrence of electrically induced hyperaemia, especially at the cathode. Studies were performed to identify means of reducing such effects. Skin vasodilator responses were measured using a laser Doppler imager that controlled iontophoretic current delivery. A novel feature involved monitoring voltage across the iontophoresis chambers. Comparison between responses to vehicle (distilled H₂O), acetylcholine (ACh) and sodium nitroprusside (SNP) showed electrically induced hyperaemia at the cathode associated with the vehicle, whose time course overlapped with that of the SNP response. Voltage across the chambers containing drugs dissolved in H₂O was significantly (p = 0.018, n = 7) lower than the voltage profile of H₂O alone. H₂O iontophoresis was associated with cathodal hyperaemic responses in most subjects, whereas a 0.5% NaCl vehicle produced lower voltages and eliminated this artefact. Voltage·time integral rather than charge was the prime determinant of electrically induced hyperaemic responses. No significant correlation was found between skin fold thickness and either calculated skin resistance (r² = 0.0002) or vascular response to ACh (r² = 0.13). Smaller chamber size led to higher voltages and greater electrically induced hyperaemic responses. These appear to be prostaglandin dependent as they were ablated by cyclooxygenase inhibition. Use of a low-resistance vehicle combined with larger chamber sizes and lower currents can prevent such artefacts, thereby increasing the robustness of this methodology for clinical assessment of endothelial function.