Role of nitric oxide in the regulation of digital pulse volume amplitude in humans

Changes in the reactive hyperemia index after continuous and interval exercise

INTRODUCTION

High-intensity interval exercise (HIIE) is more effective than moderate-intensity interval exercise (MICE) for improving macrovascular function (e.g., flow-mediated dilation), but less is known regarding the effect of HIIE on microvascular function. We used peripheral artery tonometry to measure the reactive hyperemia index (RHI) and examine the acute effects of HIIE and MICE on microvascular function.

METHODS

Ten healthy participants (50% men, age: 26 ± 5 years, mass: 75.6 ± 15.1 kg, height: 170 ± 10 cm, body mass index: 26.0 ± 3.1 kg∙m-2) performed single bouts of HIIE and MICE cycling on separate occasions. The MICE protocol was 20 min at 60% of maximum power output. The HIIE protocol was a 12-min warm up at 50% of maximum power output immediately followed by an 8-min Tabata protocol where participants alternated between cycling at ⩾ 100% max power (20 sec) and rest (10 sec). The RHI was measured before, immediately after, and 1 h after exercise and compared by two-way repeated measures analysis of variance (condition [MICE, HIIE] and time [pre-, post-, and 1-h postexercise]).

RESULTS

Compared to baseline, RHI increased 1 h after MICE only (p = 0.02). Heart rate was higher during MICE at 5 and 10 min (p = 0.02) and higher during HIIE at min 20 (p < 0.01).

CONCLUSION

Within a sample of healthy adults, the RHI was improved 1 h after a single session of MICE but not HIIE. Future research is needed to determine the significance of the differential effects of exercise regimens on the macro- and microvasculature.

Non-invasive vascular measures as prognostic predictors for older patients with non-ST elevation acute coronary syndrome

BACKGROUND

Adverse cardiac events are common in older patients with non-ST elevation acute coronary syndrome (NSTEACS), yet prognostic predictors are still lacking. This study investigated the long-term prognostic significance of non-invasive measures including endothelial function, carotid intima-media thickness (CIMT), and vascular stiffness in older NSTEACS patients referred for invasive treatment.

METHODS

NSTEACS patients aged 75 years and older recruited to a multicentre cohort study (NCT01933581) were assessed for baseline endothelial function using endoPAT logarithm of reactive hyperemia index (LnRHI), CIMT using B-mode ultrasound, and vascular stiffness using carotid-femoral pulse wave velocity (cfPWV). Long-term outcomes included major adverse cardiovascular events (MACE), a composite of death, reinfarction, urgent revascularization, stroke/transient ischemic attack, and significant bleeding.

RESULTS

Recruitment resulted in 214 patients assessed for LnRHI, 190 patients assessed for CIMT and 245 patients assessed for cfPWV. For LnRHI group (median follow-up 4.73 years [IQR: 1.41-5.00]), Cox regression analysis revealed a trend towards increased risk of MACE (HR: 1.24 [95% CI: 0.80-1.93]; P  = 0.328) and mortality (HR: 1.49 [95% CI: 0.86-2.59]; P  = 0.157), but no significance was reached. No difference for other components of MACE was found. For CIMT group (median follow up 4.74 years [IQR: 1.55-5.00]), no statistically significant difference in MACE was found (HR: 0.92 [95% CI: 0.53-1.59]; P  = 0.754). Similarly, for cfPWV group (median follow-up 4.96 years [IQR: 1.55-5.00]), results did not support prognostic significance (for MACE, HR: 0.95 [95% CI: 0.65-1.39]; P  = 0.794).

CONCLUSION

Endothelial function, CIMT and vascular stiffness were proven unsuitable as strong prognostic predictors in older patients with NSTEACS.

CLINICAL TRIAL REGISTRATION

NCT01933581.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Association between protein arginine N-methyltransferase 1 polymorphism and overt diabetic nephropathy: Role of asymmetric dimethylarginine in vascular tone

Background

ω-NG,NG-asymmetric dimethylarginine (ADMA) regulates vascular tone and may participate in the pathogenesis of diabetic nephropathy (DN).

Objective

To investigate whether single-nucleotide polymorphisms (SNPs) around the protein arginine N-methyltransferase 1 gene (PRMT1) influence ADMA dynamics and DN incidence and severity.

Methods

This study utilized a hospital-based database containing 310 Japanese patients with type 2 diabetes mellitus (T2DM). The association of PRMT1-related tagged SNPs with DN stage distribution was examined using a dominant model of minor alleles. PRMT1 mRNA, serum ADMA, reactive hyperemia-peripheral arterial tonometry index (RHI), and brachial-ankle pulse wave velocity (baPWV) were compared between the genotype-based subgroups of causal SNP, and correlations between these variables were evaluated.

Results

The composition of DN stages significantly differed between the GG and GA + AA subgroups of rs892151 (p = 0.026). In a propensity-matching cohort of rs892151, the GA + AA subgroup had an increased incidence of overt DN (odds ratio 2.92, 95 % confidence interval 1.12-7.62, p = 0.028), along with higher PRMT1 mRNA, serum ADMA levels, and baPWV than the GG subgroup (p < 0.001, p = 0.023 and 0.047, respectively). There were correlations between PRMT1 mRNA and serum ADMA levels, between serum ADMA levels and RHI, and between baPWV and urinary albumin excretion (r = 0.335, p < 0.001, r = -0.221, p = 0.029, and r = 0.254, p = 0.004, respectively).

Conclusions

T2DM patients carrying the PRMT1-related variant rs892151 were susceptible to overt DN. ADMA-mediated endothelial dysfunction and arterial stiffness may be involved in the variant-related pathogenesis of overt DN.

Hypertensive disorders of pregnancy & vascular dysfunction

Hypertensive disorders of pregnancy (HDP) are a leading cause of maternal and fetal morbidity and mortality. One of the more severe HDP diagnoses is preeclampsia, which is recognized as a sex-specific cardiovascular risk enhancer with long-term implications for women's health, increasing lifetime risk of ischemic heart disease, stroke, and heart failure. Though the mechanisms accounting for the increased risk of cardiovascular disease following HDP are not yet well understood, vascular dysfunction has been implicated. In this perspective piece, we summarize the existing evidence for vascular dysfunction in HDP with a focus on non-invasive assessments, highlight advances in the field, and suggest future directions for improving risk stratification of women with HDP.

Translational Research of the Acute Effects of Negative Emotions on Vascular Endothelial Health: Findings From a Randomized Controlled Study

BACKGROUND

Provoked anger is associated with an increased risk of cardiovascular disease events. The underlying mechanism linking provoked anger as well as other core negative emotions including anxiety and sadness to cardiovascular disease remain unknown. The study objective was to examine the acute effects of provoked anger, and secondarily, anxiety and sadness on endothelial cell health.

METHODS AND RESULTS

Apparently healthy adult participants (n=280) were randomized to an 8-minute anger recall task, a depressed mood recall task, an anxiety recall task, or an emotionally neutral condition. Pre-/post-assessments of endothelial health including endothelium-dependent vasodilation (reactive hyperemia index), circulating endothelial cell-derived microparticles (CD62E+, CD31+/CD42-, and CD31+/Annexin V+) and circulating bone marrow-derived endothelial progenitor cells (CD34+/CD133+/kinase insert domain receptor+ endothelial progenitor cells and CD34+/kinase insert domain receptor+ endothelial progenitor cells) were measured. There was a group×time interaction for the anger versus neutral condition on the change in reactive hyperemia index score from baseline to 40 minutes (P=0.007) with a mean±SD change in reactive hyperemia index score of 0.20±0.67 and 0.50±0.60 in the anger and neutral conditions, respectively. For the change in reactive hyperemia index score, the anxiety versus neutral condition group by time interaction approached but did not reach statistical significance (P=0.054), and the sadness versus neutral condition group by time interaction was not statistically significant (P=0.160). There were no consistent statistically significant group×time interactions for the anger, anxiety, and sadness versus neutral condition on endothelial cell-derived microparticles and endothelial progenitor cells from baseline to 40 minutes.

CONCLUSIONS

In this randomized controlled experimental study, a brief provocation of anger adversely affected endothelial cell health by impairing endothelium-dependent vasodilation.

Novel use of structural equation modelling to examine diet and metabolic traits associated with microvascular endothelial dysfunction in middle-aged Chinese males: a cross-sectional study

BACKGROUND

The present study aims to use structural equation modelling (SEM) with multiple regression pathways to examine direct and indirect links from diet and metabolic traits to microvascular endothelial dysfunction (ED) among middle-aged Chinese males.

METHODS

The study was conducted in middle-aged Chinese males, who underwent a health check-up between 2018 and 2019. Data on lifestyle behaviour factors (physical activity, diet pattern, sleep quality and diet data underwent factor analysis in advance) and metabolic risk factors referring to metabolic traits were introduced into the SEM to examine inter-relationship among these factors and their association with ED, as evaluated by the reactive hyperaemia index (RHI).

RESULTS

Both exploratory factor analysis and confirmatory factor analysis identified two major dietary patterns: 'prudent pattern' and 'western pattern'. The univariate test suggested that only triglycerides (TGs) and prudent dietary pattern were directly associated with RHI. Furthermore, prudent dietary pattern had an indirect association with RHI via TG (prudent diet→TG: β=-0.15, p<0.05; TG→RHI: β=-0.17, p<0.001). As to confirming the hypothesised association between variables apart, physical activity frequency was correlated to the decrease in TG (β=-0.29, p<0.001), but had no direct correlation to RHI.

CONCLUSION

The network of direct and indirect associations among diet pattern and cardiometabolic risk factors with RHI measured ED among middle-aged males. The most significant modifiable factors identified were TG and prudent diet pattern, which needs to be targeted as preventive strategies for early microvascular impairment.

Aging and Vascular Disease: A Multidisciplinary Overview

Vascular aging, i.e., the deterioration of the structure and function of the arteries over the life course, predicts cardiovascular events and mortality. Vascular degeneration can be recognized before becoming clinically symptomatic; therefore, its assessment allows the early identification of individuals at risk. This opens the possibility of minimizing disease progression. To review these issues, a search was completed using PubMed, MEDLINE, and Google Scholar from 2000 to date. As a network of clinicians and scientists involved in vascular medicine, we here describe the structural and functional age-dependent alterations of the arteries, the clinical tools for an early diagnosis of vascular aging, and the cellular and molecular events implicated. It emerges that more studies are necessary to identify the best strategy to quantify vascular aging, and to design proper physical activity programs, nutritional and pharmacological strategies, as well as social interventions to prevent, delay, and eventually revert the disease.

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

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

Longitudinal follow-up on vascular morphology and function in children with kidney transplants

AIM

Our aim was to evaluate cardiovascular risk profile in 42 children with kidney transplants (KT) at the Queen Silvia Children's Hospital, Gothenburg Sweden.

METHODS

Forty-two children (7.1-18 years) with KT, time from transplantation 3.5 (0.9-13) years, were examined at inclusion and annually for three consecutive years. Eighteen matched controls were examined once. Cardiovascular phenotyping included ultra-high-frequency ultrasound (UHFUS), pulse wave velocity (PWV), and endothelial function.

RESULTS

Children with KT had higher body mass index (BMI) z-score and blood pressure (BP) z-score than healthy controls (BMI z-score: 0.4 ± 1.0 and - 0.2 ± 0.9, respectively, p = 0.02; SBP z-score: 0.5 ± 0.9 and - 0.8 ± 0.7; DBP z-score: 0.7 ± 0.7 and - 0.3 ± 0.5, respectively, p < 0.001). BP z-score decreased significantly over 3 years; other vascular markers remained unchanged. PWV and carotid intima thickness (IT) were higher in children with KT compared to healthy controls. Children with pre-emptive KT had lower radial IT and dorsal pedal media thickness (MT) compared to children with preceding dialysis.

CONCLUSION

Children with KT show increased cardiovascular risk parameters, not increasing over time. Children on dialysis before KT have more pronounced vascular changes than those with pre-emptive KT, suggesting pre-emptive transplantation more beneficial for cardiovascular health.

Endothelial function, arterial stiffness and Framingham risk score in chronic kidney disease: A prospective observational cohort study

The aim of this study was to assess the role of endothelial function measured by the reactive hyperemia index (RHI), arterial stiffness measured by the augmentation index (AIx), and Framingham's cardiovascular disease (CVD) risk score (FRS) in kidney function decline in patients with chronic kidney disease (CKD). The RHI and AIx@75 (adjusted for 75 heart beats per minute), both derived from peripheral arterial tonometry (EndoPAT), were measured in 428 CKD patients aged 18 years old and older during hospitalization. We evaluated kidney function and its decline (incident ≥40% decline in estimated glomerular filtration rate [eGFR] or initiation of renal replacement therapy) associated with the RHI, AIx@75, and FRS during follow-up for a median of 36 months. The mean age of the participants was 56 years old, and 63.8% were men. In Spearman correlation analysis, the FRS, AIx@75, and RHI levels inversely correlated with eGFR. Over a median follow-up of 36 months, 122 participants experienced kidney function decline. In multivariate Cox analysis, only the FRS remained independently associated with the progression of kidney function (HR, 1.37; 95% CI, 1.14 to 1.64; P = 0.001). Multivariable-adjusted spline regression models showed a positive linear relationship between the FRS and the risk of kidney function decline (P-overall = 0.001, P-nonlinear = 0.701). However, adding the FRS to a model containing kidney function markers did not improve risk prediction for kidney outcome (category-free net reclassification improvement index [cf-NRI] = 0.179, P = 0.084; integrated discrimination improvement [IDI] = 0.017, P = 0.128). Additionally, the increased risk of the outcome associated with an elevated FRS was particularly evident among CKD patients with eGFR ≥60 ml/min/1.73  m² (eGFR ≥ 60 ml/min/1.73 m² vs.< 60 ml/min/1.73 m², P for interaction =  0.022). Participants with higher FRS levels were at increased risk of kidney function decline, emphasizing the important role of traditional CVD risk factors in the progression of CKD.

Nitric oxide metabolites: associations with cardiovascular biomarkers and clinical parameters in patients with HFpEF

AIMS

Heart failure with preserved ejection fraction (HFpEF) is one of the most rapidly growing cardiovascular health burden worldwide, but there is still a lack of understanding about the HFpEF pathophysiology. The nitric oxide (NO) signalling pathway has been identified as a potential key element. The aim of our study was to investigate markers of NO metabolism [l-arginine (l-Arg), homoarginine (hArg), and asymmetric and symmetric dimethylarginine (ADMA and SDMA)], additional biomarkers [N-terminal pro-B-type natriuretic peptide (NT-proBNP), endothelin-1 (ET-1), mid-regional pro-adrenomedullin (MR-proADM), copeptin, and high-sensitivity C-reactive protein (hsCRP)], and the endothelial function in an integrated approach focusing on associations with clinical characteristics in patients with HFpEF.

METHODS AND RESULTS

Seventy-three patients, prospectively enrolled in the 'German HFpEF Registry', were analysed. Inclusion criteria were left ventricular ejection fraction (LVEF) ≥ 50%; New York Heart Association functional class ≥ II; elevated levels of NT-proBNP > 125 pg/mL; and at least one additional criterion for structural heart disease or diastolic dysfunction. All patients underwent transthoracic echocardiography, cardiopulmonary exercise testing, and pulse amplitude tonometry (EndoPAT™). Patients were categorized in two groups based on their retrospectively calculated HFA-PEFF score. Serum concentrations of l-Arg, hArg, ADMA, SDMA, NT-proBNP, ET-1, MR-proADM, copeptin, and hsCRP were determined. Patients had a median age of 74 years, 47% were female, and median LVEF was 57%. Fifty-two patients (71%) had an HFA-PEFF score ≥ 5 (definitive HFpEF), and 21 patients (29%) a score of 3 to 4 (risk for HFpEF). Overall biomarker concentrations were 126 ± 32 μmol/L for l-Arg, 1.67 ± 0.55 μmol/L for hArg, 0.74 (0.60;0.85) μmol/L for SDMA, and 0.61 ± 0.10 μmol/L for ADMA. The median reactive hyperaemia index (RHI) was 1.55 (1.38;1.87). SDMA correlated with NT-proBNP (r = 0.291; P = 0.013), ET-1 (r = 0.233; P = 0.047), and copeptin (r = 0.381; P = 0.001). ADMA correlated with ET-1 (r = 0.250; P = 0.033) and hsCRP (r = 0.303; P = 0.009). SDMA was associated with the left atrial volume index (β = 0.332; P = 0.004), also after adjustment for age, sex, and comorbidities. Biomarkers were non-associated with the RHI. A principal component analysis revealed two contrary clusters of biomarkers.

CONCLUSIONS

Our findings suggest an impaired NO metabolism as one possible key pathogenic determinant in at least a subgroup of patients with HFpEF. We argue for further evaluation of NO-based therapies. Upcoming studies should clarify whether subgroups of HFpEF patients can take more benefit from therapies that are targeting NO metabolism and pathway.

Biological Assessment of the NO-Dependent Endothelial Function

Nitric oxide (NO) is implicated in numerous physiological processes, including vascular homeostasis. Reduced NO bioavailability is a hallmark of endothelial dysfunction, a prequel to many cardiovascular diseases. Biomarkers of an early NO-dependent endothelial dysfunction obtained from routine venous blood sampling would be of great interest but are currently lacking. The direct measurement of circulating NO remains a challenge due by its high reactivity and short half-life. The current techniques measure stable products from the NO signaling pathway or metabolic end products of NO that do not accurately represent its bioavailability and, therefore, endothelial function per se. In this review, we will concentrate on an original technique of low temperature electron paramagnetic resonance spectroscopy capable to directly measure the 5-α-coordinated heme nitrosyl-hemoglobin in the T (tense) state (5-α-nitrosyl-hemoglobin or HbNO) obtained from fresh venous human erythrocytes. In humans, HbNO reflects the bioavailability of NO formed in the vasculature from vascular endothelial NOS or exogenous NO donors with minor contribution from erythrocyte NOS. The HbNO signal is directly correlated with the vascular endothelial function and inversely correlated with vascular oxidative stress. Pilot studies support the validity of HbNO measurements both for the detection of endothelial dysfunction in asymptomatic subjects and for the monitoring of such dysfunction in patients with known cardiovascular disease. The impact of therapies or the severity of diseases such as COVID-19 infection involving the endothelium could also be monitored and their incumbent risk of complications better predicted through serial measurements of HbNO.

Ventilatory Muscle Training for Early Cardiac Rehabilitation Improved Functional Capacity and Modulated Vascular Function of Individuals Undergoing Coronary Artery Bypass Grafting: Pilot Randomized Clinical Trial

Background: Cardiac rehabilitation with aerobic exercises is the first strategy for nonpharmacological treatment in the postoperative period of individuals undergoing coronary artery bypass grafting (CABG) to improve functional capacity and vascular health. However, other exercise modalities remain uncertain regarding the same benefits. Objectives: Evaluation of the effect of different modalities of exercise, such as early cardiac rehabilitation on subjects submitted to CABG in the six-minute walk test (6-MWT) and on the percentage of flow-mediated dilatation (FMD) of the brachial artery. Methods: A randomized clinical trial in which 15 patients (62.7 ± 6.7 years) who underwent CABG were randomly assigned to the following groups: isometric (IG, Handgrip Jamar®), ventilatory muscle training (VG, PowerBreathe®) and control (CG, conventional respiratory and motor physiotherapy). All patients were attended to physically twice a day (20 min/session) for a consecutive week after the CABG (hospital admission). Functional capacity was assessed by 6-MWT and endothelial function was assessed through the technique of FMD, before and after (~7 days) admission to CABG. The doppler ultrasound videos were analyzed by Cardiovascular Suite® software (Quipu, Pisa, Italy) to measure %FMD. Statistics: Generalized estimation equation, followed by Bonferroni post hoc (p < 0.05). Results: Systolic, diastolic and mean arterial pressure (SBP/DBP/MAP, respectively) were 133, 76 and 95 mmHg. The groups presented walking meters (m) distance before and after intervention of: IGbasal 357.80 ± 47.15 m vs. IGpost 306.20 ± 61.63 m, p = 0.401 (+51 m); VGbasal 261.50 ± 19.91 m vs. VGpost 300.75 ± 26.29 m, p = 0.052 (+39 m); CG basal 487.83 ± 83.23 m vs. CGpost 318.00 ± 31.08, p = 0.006 (−169 m). %FMD before and after intervention was IGbasal 10.4 ± 4.8% vs. IGpost 2.8 ± 2.5%, p = 0.152; VGbasal 9.8 ± 5.1% vs. VGpost 11.0 ± 6.1%, p = 0.825; CGbasal 9.2 ± 15.8% vs. CGpost 2.7 ± 2.6%, p = 0.710 and resting mean basal blood flow was IGbasal 162.0 ± 55.0 mL/min vs. IGpost 129.9 ± 63.7 mL/min, p = 0.662; VGbasal 83.74 ± 12.4 mL/min vs. VGpost 58.7 ± 17.1 mL/min, p = 0.041; CGbasal 375.6 ± 183.7 mL/min vs. CGpost 192.8 ± 115.0 mL/min, p = 0.459. Conclusions: Ventilatory muscle training for early cardiac rehabilitation improved acute functional capacity and modulated mean flow of individuals undergoing CABG.

Early Signs of Microvascular Endothelial Dysfunction in Adolescents with Newly Diagnosed Essential Hypertension

Endothelial dysfunction represents one of the key pathomechanisms in many diseases, including hypertension. Peripheral arterial tonometry (PAT) evaluates the functional status of microvascular endothelium and offers a biomarker of early, potentially reversible, vascular damage. This study aimed to assess endothelial function using conventional and novel indices of PAT in pediatric hypertensives. As such, 100 adolescents with normal blood pressure, and essential and white-coat hypertension were examined using EndoPAT 2000. Conventional reactive hyperemia index (RHI) and novel indices of hyperemic response, including the area under the curve of hyperemic response (AUC), were evaluated. AUC was the only parameter sensitive to the effect of hypertension, with significantly lower values in essential hypertensives compared to normotensives and white-coat hypertensives (p = 0.024, p = 0.032, respectively). AUC was the only parameter significantly correlating with mean ambulatory monitored blood pressure (r = −0.231, p = 0.021). AUC showed a significant negative association with age (p = 0.039), but a significant positive association with pubertal status indexed by plasma levels of dehydroepiandrosterone (p = 0.027). This is the first study reporting early signs of microvascular endothelial dysfunction evaluated using PAT in adolescents with newly diagnosed essential hypertension. Detailed analysis of hyperemic response using overall magnitude indexed by AUC provided a more robust method compared to the conventional evaluation of RHI.

Effects of Normal Reference Range of Phosphorus and Corresponding PTH on Endothelial Function in CKD Patients

Introduction

Endothelial dysfunction commonly occurs in chronic kidney disease (CKD) patients and increases the risk for cardiovascular disease. Among CKD patients, biomarkers involved in the pathogenesis of CKD-mineral bone disorder (CKD-MBD), such as phosphorus, parathyroid hormone, and fibroblast growth factor 23, are associated with endothelial dysfunction. We investigated whether these biomarkers induce endothelial dysfunction in CKD patients with normal phosphorus levels.

Methods

This cross-sectional study examined CKD patients with normal phosphorus levels; patients with an estimated glomerular filtration rate (eGFR) &lt;15 or who were under dialysis were excluded. Iontophoresis with laser doppler flowmetry (ILDF) and peripheral arterial tonometry were performed to assess endothelial function in 85 patients. Pearson's correlation coefficient, multiple regression, and mediation analyses were performed to examine the association between CKD-MBD biomarkers and endothelial dysfunction.

Results

Endothelial dysfunction was observed in all subjects with a low response to ILDF and 27% of subjects according to peripheral arterial tonometry. Acetylcholine (Ach)-induced ILDF was significantly associated with eGFR (r = 0.22, P = 0.04), intact parathyroid hormone (iPTH; r = −0.46, P &lt; 0.01), and VCAM-1 (r = −0.36, P &lt; 0.01). The reactive hyperemia index (RHI) was significantly related to phosphorus levels (r = 0.32, P &lt; 0.01) and iPTH (r = −0.39, P = 0.02). After adjusting for eGFR, iPTH and VCAM-1 remained independent factors for predicting endothelial dysfunction measured using Ach-induced ILDF. In addition, iPTH and phosphorus levels were independent predictors for endothelial dysfunction measured using RHI in the eGFR-adjusted model. Mediation analyses showed that the individual indirect effects of iPTH were significantly affected ILDF and RHI.

Conclusion

Serum levels of phosphorus and iPTH are associated with endothelial dysfunction, even in CKD patients with normal phosphorus levels.

Effect of obstructive sleep apnoea on retinal microvascular function: a randomised controlled trial

PURPOSE

Retinal microvascular endothelial dysfunction is thought to be of importance in the development of ocular vascular diseases. Obstructive sleep apnoea (OSA) causes macrovascular endothelial dysfunction, but the effect of OSA on retinal microvascular endothelial function is not known. We aimed to determine the effect of OSA on retinal microvascular function.

METHODS

We conducted a multi-centre, double-blind, randomised, parallel, controlled trial in patients with known moderate-to-severe OSA, established on continuous positive airway pressure (CPAP). Participants were randomised to 14 nights of either continued CPAP or sham CPAP to generate a return of OSA. Retinal vascular responses to flickering light were measured using dynamic vessel analysis both at baseline and after 14 nights of intervention. The primary outcome was the change from baseline to follow-up in the area under the curve of the arteriolar response to flickering light, sham CPAP versus continued CPAP.

RESULTS

Nineteen patients were randomised to sham CPAP, and 18 patients were randomised to continued CPAP. There was no significant effect of CPAP withdrawal and return of OSA on retinal responses, with a change in the area under the curve of the arteriole response to flickering light of + 3.8 arbitrary units (95% CI - 10.6 to + 18.2, p = 0.59), sham CPAP versus continued CPAP.

CONCLUSIONS

CPAP withdrawal and a return of OSA had no significant effect on retinal microvascular responses. This contrasts with the effect of CPAP withdrawal on macrovascular endothelial function and suggests that OSA has different effects on macrovascular and microvascular endothelial function. ISRCTN 78082983, 23/10/2014, Prospectively registered.

Methods to evaluate vascular function: a crucial approach towards predictive, preventive, and personalised medicine

Endothelium, the gatekeeper of our blood vessels, is highly heterogeneous and a crucial physical barrier with the ability to produce vasoactive and protective mediators under physiological conditions. It regulates vascular tone, haemostasis, vascular inflammation, remodelling, and angiogenesis. Several cardio-, reno-, and cerebrovascular diseases begin with the dysfunction of endothelial cells, and more recently, COVID-19 was also associated with endothelial disease highlighting the need to monitor its function towards prevention and reduction of vascular dysfunction. Endothelial cells are an important therapeutic target in predictive, preventive, and personalised (3P) medicine with upmost importance in vascular diseases. The development of novel non-invasive techniques to access endothelial dysfunction for use in combination with existing clinical imaging modalities provides a feasible opportunity to reduce the burden of vascular disease.

This review summarises recent advances in the principles of endothelial function measurements. This article presents an overview of invasive and non-invasive techniques to determine vascular function and their major advantages and disadvantages. In addition, the article describes mechanisms underlying the regulation of vascular function and dysfunction and potential new biomarkers of endothelial damage. Recognising these biomarkers is fundamental towards a shift from reactive to 3P medicine in the vascular field. Identifying vascular dysfunction earlier with non-invasive or minimally invasive techniques adds value to predictive diagnostics and targeted prevention (primary, secondary, tertiary care). In addition, vascular dysfunction is a potential target for treatments tailored to the person.

New Noninvasive Methods to Evaluate Microvascular Structure and Function

The structural and functional alterations of microvessels are detected because of physiological aging and in several cardiometabolic diseases, including hypertension, diabetes, and obesity. The small resistance arteries of these patients show an increase in the media or total wall thickness to internal lumen diameter ratio (MLR or WLR), often accompanied by endothelial dysfunction. For decades, micromyography has been considered as a gold standard method for evaluating microvascular structural alterations through the measurement of MLR or WLR of subcutaneous small vessels dissected from tissue biopsies. Micromyography is the most common and reliable method for assessing microcirculatory endothelial function ex vivo, while strain-gauge venous plethysmography is considered the reference technique for in vivo studies. Recently, several noninvasive methods have been proposed to extend the microvasculature evaluation to a broader range of patients and clinical settings. Scanning laser Doppler flowmetry and adaptive optics are increasingly used to estimate the WLR of retinal arterioles. Microvascular endothelial function may be evaluated in the retina by flicker light stimulus, in the finger by tonometric approaches, or in the cutaneous or sublingual tissues by laser Doppler flowmetry or intravital microscopy. The main limitation of these techniques is the lack of robust evidence on their prognostic value, which currently reduces their widespread use in daily clinical practice. Ongoing and future studies will overcome this issue, hopefully moving the noninvasive assessment of the microvascular function and structure from bench to bedside.

Vasodilatation Measurement Using Finger Vascular Images by Near-Infrared Light and Comparison with RH-PAT

Examination of vascular endothelial function can help infer atherosclerosis progression. This study investigated whether vascular visualization by near-infrared (NIR) light can detect vasodilatation after cuff pressure release of the upper arm and what the correlation is between the brightness decrease ratio (R1) corresponding to vasodilation and the reactive hyperemia index (RHI). We obtained finger vascular images of 53 male subjects by photographing NIR light (wavelength 850 nm) transmitted through the middle phalanx of the middle finger with a charge-coupled device camera. The upper arm was compressed for 10 min using a cuff (200 mmHg), and vascular images before and after cuff compression release were obtained. We analyzed the finger vascular images by NIR light and digital pulse volume using endothelial peripheral arterial tonometry (Endo-PAT). We also calculated the average brightness of each vascular image. Using only the data of the ischemic finger, R1 was defined using the average brightness just before cuff release and the minimum average brightness after cuff release. The brightness of vascular images of the ischemic finger decreased after cuff release probably because of vasodilation. We found significant correlation between R1 and the RHI (r = 0.52; P < 0.001). R1 in the lowest RHI quartile was significantly smaller compared to the highest and second-highest RHI quartiles (P < 0.05). Vascular visualization by NIR light can detect vasodilation after cuff release. This is significantly correlated with the RHI on Endo-PAT.

Noninvasive Investigation of the Presence and Extent of Coronary Artery Disease by the Evaluation of Fingertip-Reactive Hyperemia

OBJECTIVE

Fingertip-reactive hyperemia-peripheral artery tonometry (RH-PAT) is an emerging novel noninvasive method for evaluating endothelial function. We aimed to evaluate endothelial function with fingertip-reactive hyperemia by RH-PAT in symptomatic patients undergoing elective coronary angiography and to assess the relationship between the degree of endothelial dysfunction (ED) and the presence and the severity of coronary artery disease (CAD).

SUBJECTS AND METHODS

We assessed 92 patients. Before coronary angiography, endothelial function was measured by RH-PAT and reactive hyperemia index (RHI) was obtained. For each patient, the Gensini score was calculated according to the coronary angiographic findings to evaluate the severity of CAD.

RESULTS

In CAD (+) group, RHI (1.35 ± 0.57 vs. 1.74 ± 0.46, p = 0.001) mean values were lower than CAD (-) group. In multivariate logistic regression analysis, age, high-density lipoprotein, and RHI were found to be independent parameters predicting the presence of CAD. In multivariate linear regression analysis, RHI was found to be an independent predictor associated with the severity of CAD. In receiver operating characteristic curve analysis, RHI achieved an area under the curve of 0.763 (95% confidence interval 0.663-0.846, p = 0.001) for the ability to predict the presence of CAD. A cut-off value of 1.49 for an RHI predicted the presence of CAD with a sensitivity of 75% and a specificity of 72.9%.

CONCLUSION

RH-PAT is an objective and highly reproducible test with superior diagnostic accuracy for the evaluation of ED. We found significant correlations between ED and the presence and the severity of CAD.

Peripheral arterial tonometry-PAT technology

PAT Technology is a plethysmographic based measurement method which facilitates the accurate recording of the pulsatile volume changes of the arteries of peripheral vascular beds at the distal end of the fingers over sustained periods of time. It represents a departure from previously available plethysmographic methods, in so far as it applies a uniform pressure field which completely envelopes the measured part of a digit, including its distal-most tip. Applying near diastolic blood pressure levels of pressure within the PAT probe optimizes the dynamic range of the signal, prevents confounding veno-arteriolar reflex vasoconstriction at the measurement site, reduces respiratory and movement artifacts and thus facilitates accurate long term measurement. The vascular bed of the distal phalanx of the finger is a major site of sympathetic nervous system mediated vasoconstrictor activity, and the PAT response to sympathetic changes provides a platform for accurate and robust measurement in a number of sleep and sleep related clinical areas, foremost as a patient friendly and extensively validated home sleep testing device.

Endothelial Function and Arterial Stiffness Should Be Measured to Comprehensively Assess Obstructive Sleep Apnea in Clinical Practice

Objective: An effective clinical tool to assess endothelial function and arterial stiffness in patients with obstructive sleep apnea (OSA) is lacking. This study evaluated the clinical significance of subclinical markers for OSA management in males without serious complications.

Patients/Methods: Males without serious complications were consecutively recruited. Clinical data, biomarker tests, reactive hyperemia index (RHI), and augmentation index at 75 beats/min (AIx75) measured by peripheral arterial tonometry were collected. An apnea hypopnea index (AHI) cutoff of ≥15 events/h divided the patients into two groups.

Results: Of the 75 subjects, 42 had an AHI ≥15 events/h. Patients with an AHI ≥15 events/h had higher high-sensitivity C-reactive protein, tumor necrosis factor-alpha (TNF-α), vascular endothelial growth factor, and AIx75 values than the control group but no statistical difference in RHI was observed. After controlling for confounders, TNF-α was negatively correlated with the average oxygen saturation (r = −0.258, P = 0.043). RHI was correlated with the rapid eye movement (REM) stage percentage (r = 0.306, P = 0.016) but not with AHI (P > 0.05). AIx75 was positively correlated with the arousal index (r = 0.289, P = 0.023) but not with AHI (r = 0.248, P = 0.052).

Conclusions: In males with OSA without severe complications, TNF-α and AIx75 are independently related to OSA. The role of RHI in OSA management requires further elucidation. These markers combined can comprehensively evaluate OSA patients to provide more evidence for the primary prevention of coronary heart disease and treatment response assessment.

Acute effects of moderate-intensity cycling exercise on endothelial function in young healthy men: An investigation using the reactive hyperemia index

BACKGROUND

Endothelial cells play an important role in the prevention of cardiovascular disease.

OBJECTIVE

In this study, we examined the effects of transient aerobic exercise on peripheral endothelial function.

METHODS

Twenty-seven healthy male college students were selected as subjects and randomly divided into two groups: 13 in the control group and 14 in the exercise group. The subjects in the exercise group had a 15-minute supine rest, followed by 30 minutes of cycling exercise at moderate intensity, while measuring the reactive hyperemia index (RHI), an indicator of endothelial function, before and after exercise. The subjects in the control group had a 40-minute rest, during which RHI was measured with the same timing as in the exercise group.

RESULTS

Two-factor analysis of variance revealed a statistically significant interaction effect. In the exercise group, RHI increased significantly after exercise. However, no significant change was observed in the control group. When RHI before exercise was compared between the two groups, no significant difference was found. However, RHI after exercise was significantly higher in the exercise group.

CONCLUSIONS

The results of this study suggest that 30 minutes of moderate-intensity exercise may have a favorable impact on peripheral endothelial function.

Cerebrovascular alterations in NAFLD: Is it increasing our risk of Alzheimer's disease?

Non-alcoholic fatty liver disease (NAFLD) is a multisystem disease, which has been classified as an emerging epidemic not only confined to liver-related morbidity and mortality. It is also becoming apparent that NAFLD is associated with moderate cerebral dysfunction and cognitive decline. A possible link between NAFLD and Alzheimer's disease (AD) has only recently been proposed due to the multiple shared genes and pathological mechanisms contributing to the development of these conditions. Although AD is a progressive neurodegenerative disease, the exact pathophysiological mechanism remains ambiguous and similarly to NAFLD, currently available pharmacological therapies have mostly failed in clinical trials. In addition to the usual suspects (inflammation, oxidative stress, blood-brain barrier alterations and ageing) that could contribute to the NAFLD-induced development and progression of AD, changes in the vasculature, cerebral perfusion and waste clearance could be the missing link between these two diseases. Here, we review the most recent literature linking NAFLD and AD, focusing on cerebrovascular alterations and the brain's clearance system as risk factors involved in the development and progression of AD, with the aim of promoting further research using neuroimaging techniques and new mechanism-based therapeutic interventions.

Assessment and pathophysiology of microvascular disease: recent progress and clinical implications

The development of novel, non-invasive techniques and standardization of protocols to assess microvascular dysfunction have elucidated the key role of microvascular changes in the evolution of cardiovascular (CV) damage, and their capacity to predict an increased risk of adverse events. These technical advances parallel with the development of novel biological assays that enabled the ex vivo identification of pathways promoting microvascular dysfunction, providing novel potential treatment targets for preventing cerebral-CV disease. In this article, we provide an update of diagnostic testing strategies to detect and characterize microvascular dysfunction and suggestions on how to standardize and maximize the information obtained from each microvascular assay. We examine emerging data highlighting the significance of microvascular dysfunction in the development CV disease manifestations. Finally, we summarize the pathophysiology of microvascular dysfunction emphasizing the role of oxidative stress and its regulation by epigenetic mechanisms, which might represent potential targets for novel interventions beyond conventional approaches, representing a new frontier in CV disease reduction.

Reactive hyperemia correlates with the presence of sepsis and glycocalyx degradation in the intensive care unit: a prospective cohort study

Objective

To investigate whether reactive hyperemia measured by peripheral arterial tonometry correlates with markers of endothelial dysfunction and may be used to identify sepsis in critical illness.

Methods

A prospective study was performed using a cohort of critically ill patients. Endothelial dysfunction was assessed on admission by quantifying reactive hyperemia-peripheral arterial tonometry and plasma levels of endothelin-1, soluble E-selectin, endocan and syndecan-1. Septic patients were compared to patients without evidence of infection.

Results

Fifty-eight septic patients were compared to 28 controls. The natural logarithm of reactive hyperemia-peripheral arterial tonometry was negatively correlated with cardiovascular comorbidities, disease severity and plasma levels of soluble E-selectin (p = 0.024) and syndecan-1 (p < 0.001). The natural logarithm of reactive hyperemia-peripheral arterial tonometry was lower in septic patients than in controls (0.53 ± 0.48 versus 0.69 ± 0.42, respectively). When adjusted for age, the multivariable model predicted that each 0.1-unit decrease in natural logarithm of reactive hyperemia-peripheral arterial tonometry increased the odds for infection by 14.6%. m.

Conclusion

Reactive hyperemia-peripheral arterial tonometry is closely related to soluble E-selectin and syndecan-1, suggesting an association between endothelial activation, glycocalyx degradation and vascular reactivity. Reactive hyperemia-peripheral arterial tonometry appears to be compromised in critically ill patients, especially those with sepsis.

Digital Peripheral Arterial Tonometry and Cardiovascular Disease Events: The Framingham Heart Study

Background and Purpose

Novel noninvasive measures of vascular function are emerging as subclinical markers for cardiovascular disease (CVD) and may be useful to predict CVD events. The purpose of our prospective study was to assess associations between digital peripheral arterial tonometry (PAT) measures and first-onset major CVD events in a sample of FHS (Framingham Heart Study) participants.

Methods

Using a fingertip PAT device, we assessed pulse amplitude in Framingham Offspring and Third Generation participants (n=3865; mean age, 55±14 years; 52% women) at baseline and in 30-second intervals for 4 minutes during reactive hyperemia. The PAT ratio (relative hyperemia index) was calculated as the post-to-pre occlusion pulse signal ratio in the occluded arm, relative to the same ratio in the control (nonoccluded) arm, and corrected for baseline vascular tone. Baseline pulse amplitude and PAT ratio during hyperemia are measures of pressure pulsatility and microvascular function in the finger, respectively. We used Cox proportional hazards regression to relate PAT measures in the fingertip to incident CVD events.

Results

During follow-up (median, 9.2 years; range, 0.04–10.0 years), 270 participants (7%) experienced new-onset CVD events (n=270). In multivariable models adjusted for cardiovascular risk factors, baseline pulse amplitude (hazard ratio [HR] per 1 SD, 1.04 [95% CI, 0.90–1.21]; P=0.57) and PAT ratio (HR, 0.95 [95% CI, 0.84–1.08]; P=0.43) were not significantly related to incident composite CVD events, including myocardial infarction or heart failure. However, higher PAT ratio (HR, 0.76 [95% CI, 0.61–0.94]; P=0.013), but not baseline pulse amplitude (HR, 1.15 [95% CI, 0.89–1.49]; P=0.29), was related to lower risk for incident stroke. In a sensitivity analysis by stroke subtype, higher PAT ratio was related to lower risk of incident ischemic stroke events (HR, 0.68 [95% CI, 0.53–0.86]; P=0.001).

Conclusions

Novel digital PAT measures may represent a marker of stroke risk in the community.

Use of peripheral arterial tonometry in detection of abnormal coronary flow reserve

BACKGROUND

We assessed the utility of EndoPAT, a device that measures reactive hyperemia index (RHI) as a clinical screening tool for identifying low coronary flow reserve (CFR). Distinguishing normal from low CFR aids assessment for coronary microvascular dysfunction (CMD) or large vessel coronary artery disease (CAD).

METHODS

From June 2014-May 2019, in a convenience sample, we measured RHI in adults undergoing clinically indicated cardiac Rubidium-82 positron emission tomography/computed tomography (PET/CT) at a single center. Exclusion criteria were inability to consent, lack of English proficiency, and physical limitation. We defined low RHI as <1.67 and low CFR as <2.5. Distribution of RHI was skewed so we used its natural logarithm (LnRHI) to calculate Pearson correlation and area under the curve (AUC).

RESULTS

Of 265 patients with PET/CT, we enrolled 131, and 100 had adequate data. Patients had a mean age of 61 years (SD = 12), 46% were female, 29% non-white. Thirty-six patients had low RHI, and 60 had depressed CFR. LnRHI did not distinguish patients with low from normal CFR (AUC = 0.53; 95% Cl, 0.41-0.64) and did not correlate with CFR (r = -0.021, p = 0.83). Low RHI did not distinguish patients with traditional CAD risk factors, presence of calcification, or perfusion defect (p > 0.05). Conversely, mean augmentation index, a measure of arterial stiffness, was higher with low RHI (p = 0.005) but not CFR (p = 0.625). RHI was lower in patients we identified as CMD (low CFR, no perfusion defect and calcium score of 0) (1.88 versus 2.21, p = 0.35) although we were underpowered (n = 12) to meet statistical significance.

CONCLUSIONS

Peripheral RHI is insufficient as a clinical screening tool for low CFR as measured by cardiac PET/CT. Differences in vascular pathology assessed by each method may explain this finding.

Inflammatory Mechanisms Contributing to Endothelial Dysfunction

Maintenance of endothelial cell integrity is an important component of human health and disease since the endothelium can perform various functions including regulation of vascular tone, control of hemostasis and thrombosis, cellular adhesion, smooth muscle cell proliferation, and vascular inflammation. Endothelial dysfunction is encompassed by complex pathophysiology that is based on endothelial nitric oxide synthase uncoupling and endothelial activation following stimulation from various inflammatory mediators (molecular patterns, oxidized lipoproteins, cytokines). The downstream signaling via nuclear factor-κB leads to overexpression of adhesion molecules, selectins, and chemokines that facilitate leukocyte adhesion, rolling, and transmigration to the subendothelial space. Moreover, oscillatory shear stress leads to pro-inflammatory endothelial activation with increased monocyte adhesion and endothelial cell apoptosis, an effect that is dependent on multiple pathways and flow-sensitive microRNA regulation. Moreover, the role of neutrophil extracellular traps and NLRP3 inflammasome as inflammatory mechanisms contributing to endothelial dysfunction has recently been unveiled and is under further investigation. Consequently, and following their activation, injured endothelial cells release inflammatory mediators and enter a pro-thrombotic state through activation of coagulation pathways, downregulation of thrombomodulin, and an increase in platelet adhesion and aggregation owing to the action of von-Willebrand factor, ultimately promoting atherosclerosis progression.

Impaired Peripheral Microvascular Function and Risk of Major Adverse Cardiovascular Events in Patients With Coronary Artery Disease

[Figure: see text].

Sedentary Work and Physiological Markers of Health

The purpose of this study is to examine associations between objectively measured workplace sedentary behavior and physiological markers of health. We hypothesize that increased sedentary time and more frequent bouts of uninterrupted sitting are associated with increased hemoglobin A1c, increased blood pressure, and impaired endothelial function. Call center employees (N = 241) were enrolled from four worksites in the United States. Participants completed a survey and a physical health assessment. Sedentary behavior and sitting/standing time at work were quantified using an accelerometer. Hemoglobin A1c was measured using a finger-prick and portable analyzer. Blood pressure was measured with an automated cuff, and vascular endothelial function was assessed in a subsample of participants (n = 56) using EndoPAT. We analyzed data with two series of ordinary least squares regressions, first to examine relationships between bouts of uninterrupted sitting and physiological outcomes, and second to examine relationships between physical activity and sitting/standing time at work and physiological outcomes. The sample was primarily female, and on average was obese, prehypertensive, and prediabetic. There were no significant relationships between bouts of uninterrupted sitting or physical activity/sitting/standing time at work and physiological outcomes. In a sample that is predominantly sedentary, at risk for cardiovascular disease, and prediabetic, there are no significant associations between workplace sedentary behavior and physiological markers. The lack of associations could be related to either physiological adaptations or ceiling effects in this sample.

Noninvasive peripheral vascular function, incident cardiovascular disease, and mortality in the general population

Aims 

Evidence suggests that peripheral vascular function is related to cardiovascular disease (CVD) and mortality. We evaluated the associations of non-invasive measures of flow-mediated dilatation and peripheral arterial tonometry with incident CVD and mortality.

Methods and results 

In a post-hoc analysis of the community-based Gutenberg Health Study, median age 55 years (25th/75th percentile 46/65) and 49.5% women, we measured brachial artery flow-mediated dilatation (N=12 599) and fingertip peripheral arterial tonometry (N=11 125). After a follow-up of up to 11.7 years, we observed 595 incident CVD events, 106 cardiac deaths, and 860 deaths in total. Survival curves showed decreased event-free survival with higher mean brachial artery diameter and baseline pulse amplitude and better survival with higher mean flow-mediated dilatation and peripheral arterial tonometry ratio (all P_{log rank} <0.05). In multivariable-adjusted Cox regression analyses only baseline pulse amplitude was inversely related to mortality [hazard ratio (HR) per standard deviation increase, 0.86, 95% confidence interval (95% CI), 0.79–0.94; P=0.0009]. After exclusion of individuals with prevalent CVD the association was no longer statistically significant in multivariable-adjusted models (HR 0.91, 95% CI 0.81–1.02; P=0.11). None of the vascular variables substantially increased the C-index of a model comprising clinical risk factors.

Conclusions 

In our cohort, non-invasive measures of peripheral vascular structure and function did not reveal clinically relevant associations with incident CVD or mortality. Whether determination of pulse amplitude by peripheral arterial tonometry improves clinical decision-making in primary prevention needs to be demonstrated.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

TRIAL REGISTRATION

ClinicalTrials.gov NCT01550315; March 9, 2012.

Relationship between peripheral arterial reactive hyperemia and the index of myocardial resistance in patients undergoing invasive coronary angiography

BACKGROUND

Coronary microvascular dysfunction is a powerful prognostic factor in patients with coronary artery disease. We investigated the role of reactive digital hyperemia peripheral arterial tonometry (RH-PAT) as a non-invasive tool to identify patients with impaired coronary microvasculature.

METHODS

Patients undergoing elective coronary angiography were consecutively assessed for peripheral microvascular endothelial function before coronary angiography: both the Reactive Hyperemic Index (RHI) and the Framingham reactive hyperemic index (Endoscore) were measured. During coronary angiography, the Index of microvascular resistance (IMR) was measured in all patients, and an IMR value > 25 identified patients with coronary microvascular impairment.

RESULTS

A total of 47 patients with chronic coronary syndromes candidate to coronary angiography were included. Those with coronary microvascular impairment (n = 18 [38%]) presented with significantly lower RHI (1.68 ± 0.38 vs. 1.94 ± 0.93, p = 0.04) and Endoscore 0.50 ± 0.23 vs. 0.64 ± 0.23, p = 0.04) values as compared with patients with preserved coronary microvasculature. A significant relationship was observed between IMR with both RHI (r = 0.35, p = 0.02) and Endoscore (r = 0.34, p = 0.02). At the multivariable analysis, RHI and Endoscore were the only independent predictors of an IMR > 25.

CONCLUSIONS

Our study demonstrates that digital reactive hyperemia indexes are lower in patients with high IMR values, suggesting a role for RH-PAT as non-invasive tool for identifying patients with coronary microvascular impairment.

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

ABSTRACT

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

Endothelial Dysfunction Is Associated with Cerebrovascular Events in Pre-Dialysis CKD Patients: A Prospective Study

Background: Patients with chronic kidney disease (CKD) have markedly increased rates of end stage renal disease, major adverse cardiovascular/cerebrovascular events (MACCEs), and mortality. Endothelial dysfunction (ED) is an early marker of atherosclerosis that is emerging as an increasingly important non-traditional cardiovascular risk factor in CKD. There is a lack of clinical studies examining the association between ED and both cardiovascular and renal endpoints in patients with CKD. Aims: We examined the association between reactive hyperemia index (RHI), a validated measure of endothelial function measured by peripheral arterial tonometry (PAT), with traditional cardiovascular risk factors in pre-dialysis CKD patients and prospectively evaluated the role of RHI as predictor of renal and cardiovascular outcomes in this population. Methods: One hundred and twenty pre-dialysis patients with CKD stages 1 to 5 (CKD group) and 18 healthy kidney donor candidates (control group) were recruited and had a successful RHI measurement by PAT. General demographic and clinical information including traditional cardiovascular risk factors were registered from all participants. Thereafter, patients were prospectively followed-up for a median time of 47 (IQR 19–66) months to determine associations of RHI with renal outcomes, MACCEs, hospitalizations or mortality. Results: In the CKD patient population, the mean age was 57.7 ± 15.5 years, the mean eGFR was 54.9 ± 36.7 mL/min/1.73 m² (CKD-EPI) and 57 were males (47.5%). At baseline, in univariate analysis, RHI in the CKD group correlated positively with eGFR (r = 0.332, p < 0.0001) and correlated negatively with age (r = −0.469, p < 0.0001), Charlson index (r = −0.399, p < 0.0001), systolic blood pressure (r = −0.256, p = 0.005), and proteinuria (r = 0.211, p = 0.027). Reactive hyperemia index in the control group did not significantly differ from RHI observed in patients with CKD stages 1 to 5 (2.09 ± 0.40 vs. 2.01 ± 0.06, p = 0.493). In adjusted analysis, only age (β = −0.014, p = 0.003) remained independently associated with RHI at baseline. During follow-up, 8 patients suffered a MACCEs, 33 patients experienced renal function deterioration, 17 patients were hospitalized for medical reasons and 6 patients died. RHI at baseline was not significantly associated with CKD progression (1.94 vs. 2.02, p = 0.584), hospitalizations (1.90 vs. 2.04, p = 0.334), and all-cause mortality (1.65 vs. 2.01, p = 0.208) or MACCEs (1.77 vs. 2.01, p = 0.356), but was significantly associated with cerebrovascular events (1.27 vs. 2.02, p = 0.004) and with a composite cardiovascular outcome (MACCEs, hospital admissions and death; 1.73 vs. 2.07, p = 0.035). Conclusion: Our results suggest that RHI may be a predictor for the development of cerebrovascular events in pre-dialysis CKD patients who may benefit from more aggressive preventive measures.

Endothelial function in cardiovascular medicine: a consensus paper of the European Society of Cardiology Working Groups on Atherosclerosis and Vascular Biology, Aorta and Peripheral Vascular Diseases, Coronary Pathophysiology and Microcirculation, and Thrombosis

Endothelial cells (ECs) are sentinels of cardiovascular health. Their function is reduced by the presence of cardiovascular risk factors, and is regained once pathological stimuli are removed. In this European Society for Cardiology Position Paper, we describe endothelial dysfunction as a spectrum of phenotypic states and advocate further studies to determine the role of EC subtypes in cardiovascular disease. We conclude that there is no single ideal method for measurement of endothelial function. Techniques to measure coronary epicardial and micro-vascular function are well established but they are invasive, time-consuming, and expensive. Flow-mediated dilatation (FMD) of the brachial arteries provides a non-invasive alternative but is technically challenging and requires extensive training and standardization. We, therefore, propose that a consensus methodology for FMD is universally adopted to minimize technical variation between studies, and that reference FMD values are established for different populations of healthy individuals and patient groups. Newer techniques to measure endothelial function that are relatively easy to perform, such as finger plethysmography and the retinal flicker test, have the potential for increased clinical use provided a consensus is achieved on the measurement protocol used. We recommend further clinical studies to establish reference values for these techniques and to assess their ability to improve cardiovascular risk stratification. We advocate future studies to determine whether integration of endothelial function measurements with patient-specific epigenetic data and other biomarkers can enhance the stratification of patients for differential diagnosis, disease progression, and responses to therapy.

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

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

Assessment of macrovascular and microvascular function in aging males

Aging is associated with reductions in endothelial function, observations primarily reported using brachial artery ultrasound. There is growing interest in the use of peripheral artery tonometry (PAT) of microvessels in the fingertip to assess endothelial function because it is less technically demanding and has a high sensitivity and specificity for assessing coronary endothelial function. Moreover, similar to brachial artery flow-mediated dilation (FMD), PAT predicts cardiovascular disease outcomes. However, the relationship between PAT and FMD have yet to be examined in the context of aging. To address this question, reactive hyperemic index (RHI) using EndoPAT and FMD using brachial artery ultrasound were assessed after 5 min of forearm ischemia in 20 younger (18-40 yr old; 29 ± 4 yr) and 20 older (60-75 yr old; 65 ± 4 yr) healthy adult men. Higher values of both FMD and RHI indicate better endothelial function. Endothelial function assessed via brachial artery FMD was lower in older (4.8 ± 2.1%), compared with younger (7.5 ± 1.6%) men (P < 0.001). In contrast, the RHI assessed via PAT was greater in older (2.2 ± 0.6), compared with younger (1.8 ± 0.5) men (P = 0.014). FMD and RHI were not correlated (r = -0.15; P = 0.35). We conclude that PAT may not be an appropriate measure to evaluate age-associated changes in endothelial function.NEW & NOTEWORTHY Microvessel endothelial function assessed via finger plethysmography may not reflect age-associated reductions in large artery endothelial function assessed via brachial artery flow-mediated dilation.

Acute effects of oral triglyceride load on dynamic changes in peripheral endothelial function in heart failure patients with reduced ejection fraction and healthy controls

BACHGROUND

Postprandial hyperlipaemia impairs endothelial function, possibly via oxidative-stress-mediated mechanisms. The aim of this study was to evaluate the acute effects of an oral triglyceride load (OTGL) on peripheral endothelial function in heart failure patients with reduced ejection fraction (HFrEF) compared to healthy controls.

DESIGN

Prospective cross-sectional.

METHODS

We enrolled 47 patients with HFrEF and 20 healthy controls. Peripheral endothelial function was assessed with EndoPAT2000 technology using a reactive hyperaemia index (RHI) and pulse wave amplitude (PWA) at baseline (after 8-h overnight fasting) as well as 1, 2, 3 and 4-h post-OTGL consumption (250-ml cream drink). Pulse wave amplitude index (PWAI) was calculated as a ratio of PWA at each time point to the baseline PWA.

RESULTS

RHI at baseline was lower in HFrEF patients compared to controls (1.7 ± 0.3 and 2.3 ± 0.6, respectively; P = 0.001). The OTGL accounted for a physiologic increase in PWA in healthy controls (p = 0.01), but this change was not observed in HFrEF patients. After 4 h, vasodilator response was significantly increased in healthy controls but not patients with HFrEF (2.3 ± 1.3 vs. 1.3 ± 0.8 respectively, P < 0.05).

CONCLUSIONS

The main finding of this study was the impaired postprandial dynamic changes in peripheral endothelial function in patients with HFrEF compared to healthy controls. A high-fat load that caused acute hypertriglyceridaemia significantly increased resting blood flow and peak flow at reactive hyperaemia in healthy subjects. By contrast, patients with HFrEF exhibited impaired dynamic changes in peripheral endothelial function after oral triglyceride load.

A Whole-Diet Approach Affects Not Only Fasting but Also Postprandial Cardiometabolic Risk Markers in Overweight and Obese Adults: A Randomized Controlled Trial

BACKGROUND

Current dietary recommendations for cardiovascular disease (CVD) prevention focus more on dietary patterns than on single nutrients. However, randomized controlled trials using whole-diet approaches to study effects on both fasting and postprandial CVD risk markers are limited.

OBJECTIVE

This randomized parallel trial compared the effects of a healthy diet (HD) with those of a typical Western diet (WD) on fasting and postprandial CVD risk markers in overweight and obese adults.

METHODS

After a 2-wk run-in period, 40 men and women (50-70 y; BMI: 25-35 kg/m2) consumed the HD (high in fruit and vegetables, pulses, fibers, nuts, fatty fish, polyunsaturated fatty acids; low in salt and high-glycemic carbohydrates; n = 19) or the WD (less fruit, vegetables, and fibers; no nuts and fatty fish; and more saturated fatty acids and simple carbohydrates; n = 21) for 6 wk. Fasting and postprandial cardiometabolic risk markers were assessed as secondary outcome parameters during a 5-h mixed-meal challenge, and a per protocol analysis was performed using 1-factor ANCOVA or linear mixed models.

RESULTS

Differences in diet-induced changes are expressed relative to the HD group. Changes in fasting plasma total cholesterol (-0.57 ± 0.12 mmol/L, P < 0.001), LDL cholesterol (-0.41 ± 0.12 mmol/L, P < 0.01), apolipoprotein B100 (-0.09 ± 0.03 g/L, P < 0.01), and apolipoprotein A1 (-0.06 ± 0.03 g/L, P = 0.05) were significantly different between the diet groups. Changes in postprandial plasma triacylglycerol (diet × time, P < 0.001) and apolipoprotein B48 (P < 0.01) differed significantly between the groups with clear improvements on the HD, although fasting triacylglycerols (-0.24 ± 0.13 mmol/L, P = 0.06) and apolipoprotein B48 (1.04 ± 0.67 mg/L, P = 0.40) did not. Significant differences between the diets were also detected in fasting systolic (-6.9 ± 3.1 mmHg, P < 0.05) and 24-h systolic (-5.0 ± 1.7 mmHg, P < 0.01) and diastolic (-3.3 ± 1.1 mmHg, P < 0.01) blood pressure.

CONCLUSION

A whole-diet approach targeted multiple fasting and postprandial CVD risk markers in overweight and obese adults. In fact, the postprandial measurements provided important additional information to estimate CVD risk. This trial is registered at clinicaltrials.gov as NCT02519127.

The effect of dietary nitrate and vitamin C on endothelial function, oxidative stress and blood lipids in untreated hypercholesterolemic subjects: A randomized double-blind crossover study

BACKGROUND

Vitamin C may enhance nitric oxide (NO) production through stepwise reduction of dietary nitrate (NO₃) to nitrite (NO₂) to NO. The combined effect of vitamin C and NO₃ supplementation is relatively unexplored in untreated hypercholesterolemia.

AIMS

We aimed to examine whether co-administration of vitamin C and nitrate for 4-weeks would improve endothelial function (primary outcome), plasma NO metabolites, oxidative stress, and blood lipids (secondary outcomes).

METHODS

Subjects 50-70 years of age with low density lipoprotein (LDL) > 130 mg/dL and RHI ≤2 were enrolled in this randomized double-blind crossover study. Subjects were assigned to two 4-week supplementation treatments starting with 70 ml of concentrated beetroot juice (CBJ) with 1000 mg of vitamin C (NC) or CBJ with matched placebo (N), then switched to alternate treatment following 2-week washout. The change in reactive hyperemia index (RHI), sum of plasma NO metabolites (NO₂ + NO₃ (NOx)), oxidized LDL (oxLDL), and serum lipids were assessed at baseline and at 4-weeks of each treatment period.

RESULTS

Eighteen subjects (11M:7F) completed all study visits. No significant treatment differences were observed in RHI change (N: 0.21 ± 0.12; NC: 0.20 ± 0.17; p = 0.99). Secondary analysis revealed that a subgroup of NC subjects who started with a baseline RHI of <1.67 (threshold value for ED) had greater improvements in RHI compared to subjects with RHI >1.67 (1.23 ± 0.15 to 1.96 ± 0.19; n = 8 vs. 1.75 ± 0.11 to 1.43 ± 0.10; n = 8; p = 0.02). Compared to N, NC experienced a significant increase in plasma NOx (N: 94.2 ± 15.5 μmol/L; NC: 128.7 ± 29.1 μmol/L; p = 0.01). Although there was no significant difference in oxLDL change between treatments (N: -1.08 ± 9.8 U/L; NC: -6.07 ± 9.14 U/L; p = 0.19), NC elicited significant reductions in LDL (N: 2.2 ± 2; NC: -10.7 ± 23; p = 0.049), triglycerides (N: 14.6 ± 43; NC: -43.7 ± 45; p = 0.03), and no change in serum high density lipoprotein. Within treatment group comparisons showed that only NC reduced oxLDL significantly from baseline to 4 weeks (p = 0.01).

CONCLUSIONS

No between intervention differences were observed in RHI. RHI only improved in NC subjects with ED at intervention baseline. Four weeks of NC enriched the NO pool and promoted reduction of blood lipids and oxidative stress in subjects with hypercholesterolemia. These preliminary findings highlight a supplementation strategy that may reduce the progression of atherosclerotic disease and deserves further attention in studies using flow mediated dilation methods.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov (NCT04283630).

Effects of short-term consumption of strawberry powder on select parameters of vascular health in adolescent males

Cardiovascular disease is a leading cause of death in the United States and much of the developed world, costing billions of dollars in lost work time, lower productivity and high health care expenditures. Research on foods and bioactive food components that have cardioprotective benefits may provide new insights as to how modest changes in one's diet may result in a reduced risk of vascular disease. In intervention trials, the consumption of strawberries, either fresh or freeze-dried, has been reported to improve select markers of cardiovascular health, including improved lipid profiles, microvascular function, and platelet reactivity. Consistent with the above, epidemiological studies suggest beneficial effects of strawberries on vascular function. Preliminary studies on the effects of freeze-dried strawberry powder on vascular health are reviewed in the current paper.

Cardiovascular Outcomes in Young Adulthood in a Population-Based Very Low Birth Weight Cohort

OBJECTIVES

To assess differences in left heart structure and function, and endothelial function in a national cohort of very low birth weight (VLBW) young adults and term-born controls.

STUDY DESIGN

The New Zealand VLBW study is a prospective, population-based, longitudinal cohort study which included all infants born <1500 g in 1986. The VLBW cohort (n = 229; 71% of survivors) and term-born controls (n = 100), were assessed at age 26-30 years. Measures of left heart structure and function were evaluated by echocardiography, vascular function was assessed using blood pressure, reactive hyperemia index, and arterioventricular coupling by calculating left ventricular (LV) and arterial elastance.

RESULTS

Compared with controls, those born VLBW had smaller LVs, even when indexed for body surface area (mean LV mass, 89.7 ± 19.3 g/m² vs 95.0 ± 22.3 g/m² [P = .03]; LV end-diastolic volume, 58.3 ± 10.9 mL/m² vs 62.4 ± 12.4 mL/m² [P = .002]; and LV end-systolic volume, 20.8 ± 4.9 mL/m² vs 22.6 ± 5.8 mL/m² [P = .004]). VLBW participants had lower stroke volume (median, 37.2 mL/m² [IQR, 33-42 mL/m²] vs median, 40.1 mL/m² [IQR, 34-45 mL/m²]; P = .0059) and cardiac output (mean, 4.8 ± 1.2 L/min vs 5.1 ± 1.4 L/min; P = .03), but there was no difference in ejection fraction. The VLBW group had higher LV elastance (3.37 ± 0.88 mm Hg/mL vs 2.86 ± 0.75 mm Hg/mL; P < .0001) and arterial elastance (1.84 ± 0.4 vs 1.6 ± 0.4; P < .0001) and lower reactive hyperemia index (0.605 ± 0.28 vs 0.688 ± 0.31; P = .041). These measures were influenced by birth weight and sex, but we found limited associations with other perinatal factors.

CONCLUSIONS

Being born preterm and VLBW is associated with differences in cardiovascular structure and function in adulthood. This population may be more vulnerable to cardiovascular pathology as they age.

TRIAL REGISTRATION

Australian Clinical Trials Registry ACTRN12612000995875.

Association of coronary calcium score with endothelial dysfunction and arterial stiffness

BACKGROUND AND AIMS

The aim of the study was to determine potential associations between endothelial dysfunction and arterial stiffness, measured by peripheral arterial tonometry, and coronary artery calcium score (CACS) assessed by computed tomography (CT).

METHODS AND RESULTS

The BIG3 study is a prospective longitudinal, non-interventional, pulmonary-cardiovascular cohort study exploring the three major smoking-induced diseases: cardiovascular disease, chronic obstructive pulmonary disease, and lung cancer, in a 45-75 aged cohort (mean 62 years), enriched in smokers. Computed tomography of the chest with assessment of CACS was performed in a selected subset of the participants (n = 2080). Peripheral arterial tonometry (EndoPAT) was used to assess endothelial function and arterial stiffness measured as reactive hyperaemia index (RHI) and augmentation index (AI), respectively. We observed significant associations of CACS, endothelial dysfunction, and arterial stiffness with several risk factors for coronary heart disease including age, sex, BMI, diabetes mellitus, and blood pressure. There was significant association of CACS, classified into three levels of severity, with RHI and AI (p = 0.0005 and p = 0.0009, respectively). For groups of increasing CACS (0, 1-400 and > 400 Agatston score), RHI decreased from median 1.89 (1.58-2.39), and 1.93 (1.62-2.41) to 1.77 (1.51-2.10). AI increased from median 14.3 (5.7-25.2), and 16.4 (8.1-27.6) to 18.0 (9.1-29.2). RHI, but not AI, remained significantly associated with CACS after risk factors adjustment.

CONCLUSIONS

In this large study of coronary artery calcium and vascular function, we found an association between CACS and both endothelial dysfunction and arterial stiffness, indicating that they may reflect similar mechanisms for development of cardiovascular disease.

The importance of endothelial dysfunction in resistance artery remodelling and cardiovascular risk

AIMS

The relationship between resistance artery remodelling and endothelial function remains unknown. In this study, we assessed (i) the capacity of endothelial function and nitric oxide (NO) availability to provide more information on the severity of resistance artery remodelling than common cardiovascular risk factors in subjects at low or high cardiovascular risk; and (ii) differences between patterns of resistance artery remodelling associated with deficit of NO availability and with exposure to cardiovascular risk factors.

METHODS AND RESULTS

All analyses were conducted on the microvascular data set of the Italian Society for Arterial Hypertension (SIIA) that includes 356 patients with measures of small resistance arteries remodelling acquired with pressure or wire myography. Information on endothelial function and NO availability were also available in 116 patients. The European Heart Score (HS) was used to define the total cardiovascular risk of each patient. Endothelial function was inversely related with the severity of the resistance artery remodelling, and this association remained significant after adjustment for the HS. By contrast, the HS lost its significant association with the media-to-lumen (M/L) ratio and the media cross-sectional area after adjustment for endothelial function. The strength of these associations was similar in subjects at high and low cardiovascular risk. The addition of endothelial function and NO availability to the HS significantly improved the identification of subjects at more and less severe resistance artery remodelling. A severe deficit of NO availability was associated with hypertrophic remodelling, while a higher HS was more clearly associated with eutrophic remodelling.

CONCLUSION

Resistance artery endothelial function and NO availability might represent important factors involved in resistance artery remodelling, independently from cardiovascular risk factor exposure.

Secondary Raynaud's phenomenon is associated with microvascular peripheral endothelial dysfunction

Previous studies in patients with Raynaud's phenomenon (RP) have found an association between microvascular abnormalities assessed by nail fold capillaroscopy and macrovascular peripheral endothelial dysfunction (PED), but the association between RP and nitric oxide related (NO) microvascular PED is not yet established. We performed a retrospective cross-sectional analysis of patients who were referred to Mayo Clinic between 2006 and 2014 for routine cardiovascular evaluation and who underwent evaluation of Reactive Hyperemia Peripheral Arterial Tonometry (index <2 consistent with PED). Identification of the presence of RP was determined by retrospective chart review. Six hundred sixty six individuals were included in this study (mean age 51.9 ± 13.5 years, 411 (61.3%) women), 637 (95.1%) individuals did not have RP (control group), and 29 (4.3%) had secondary RP. Only 4 patients had primary RP and were thus excluded from the final analyses. In a multivariate analysis adjusting for age, sex, smoking status, and use of statins we found a significant association between secondary RP and microvascular PED in all patients (Odds ratio: 2.45; 95% confidence interval 1.13-5.34; P = 0.0236) that remained significant in women after stratifying by sex. Secondary RP is associated with microvascular PED, detected using a non-invasive NO-dependent method. Early detection of microvascular PED could help in identifying individuals with secondary RP who are at risk for developing connective tissue disease as well as CVD.