Assessment Of Vascular Health Research Articles

Novel theory and potential applications of central diastolic pressure decay time constant

Central aortic diastolic pressure decay time constant (τ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\uptau }$$\\end{document}) is according to the two-element Windkessel model equal to the product of total peripheral resistance (R\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$R$$\\end{document}) times total arterial compliance (C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C$$\\end{document}). As such, it is related to arterial stiffness, which has considerable pathophysiological relevance in the assessment of vascular health. This study aimed to investigate the relationship of the constant τ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\uptau }$$\\end{document} with the product TMBPcPP\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$T\\frac{MBP}{{cPP}}$$\\end{document}, given by heart period (T\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$T$$\\end{document}) times the ratio of mean blood pressure (MBP) to central pulse pressure (cPP\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$cPP$$\\end{document}). The relationship was derived by performing linear fitting on an in silico population of n1 = 3818 virtual subjects, and was subsequently evaluated on in vivo data (n2 = 2263) from the large Asklepios study. The resulted expression was found to be τ=k′TMBPcPP,\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\uptau } = k^{\\prime}T\\frac{MBP}{{cPP}},$$\\end{document} with k′=0.7\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$k^{\\prime} = 0.7$$\\end{document} (R2 = 0.9). The evaluation of the equation on the in vivo human data reported high agreement between the estimated and reference τ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\uptau }$$\\end{document} values, with a correlation coefficient equal to 0.94 and a normalized RMSE equal to 5.5%. Moreover, the analysis provided evidence that the coefficient k′\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$k^{\\prime}$$\\end{document} is age- and gender-independent. The proposed formula provides novel theoretical insights in the relationship between τ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\uptau }$$\\end{document} and central blood pressure features. In addition, it may allow for the evaluation of τ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\uptau }$$\\end{document} without the need for acquiring the entire central blood pressure wave, especially when an approximation of the cPP\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$cPP$$\\end{document} is feasible. This study adds to the current literature by contributing to the accessibility of an additional biomarker, such as the central diastolic pressure decay time constant, for the improved assessment of vascular ageing.

On the similarity between aortic and carotid pressure diastolic decay: a mathematical modelling study

Aortic diastolic pressure decay (DPD) has been shown to have considerable pathophysiological relevance in the assessment of vascular health, as it is significantly affected by arterial stiffening. Nonetheless, the aortic pressure waveform is rarely available and hence the utility of the aortic DPD is limited. On the other hand, carotid blood pressure is often used as a surrogate of central (aortic) blood pressure in cardiovascular monitoring. Although the two waveforms are inherently different, it is unknown whether the aortic DPD shares a common pattern with the carotid DPD. In this study, we compared the DPD time constant of the aorta (aortic RC) and the DPD time constant of the carotid artery (carotid RC) using an in-silico-generated healthy population from a previously validated one-dimensional numerical model of the arterial tree. Our results demonstrated that there is near-absolute agreement between the aortic RC and the carotid RC. In particular, a correlation of ~ 1 was reported for a distribution of aortic/carotid RC values equal to 1.76 ± 0.94 s/1.74 ± 0.87 s. To the best of our knowledge, this is the first study to compare the DPD of the aortic and the carotid pressure waveform. The findings indicate a strong correlation between carotid DPD and aortic DPD, supported by the examination of curve shape and the diastolic decay time constant across a wide range of simulated cardiovascular conditions. Additional investigation is required to validate these results in human subjects and assess their applicability in vivo.

Is There a Role for Imaging Youth at Risk of Atherosclerosis?

Cardiovascular (CV) risk factors such as dyslipidemia, hypertension, diabetes, and obesity are associated with an increased risk for CV events in adults. Noninvasive measures of vascular health are associated with these CV events and can potentially help risk stratify children with CV risk factors. The purpose of this review is to summarize recent literature regarding vascular health in children with cardiovascular risk factors. Adverse changes in pulse wave velocity, pulse wave analysis, arterial distensibility, and carotid intima-media thickness are seen in children with CV risk factors supporting potential utility in risk stratification. Assessing vascular health in children can be challenging due to growth-related changes in vasculature, multiple assessment modalities, and differences in normative data. Vascular health assessment in children with cardiovascular risk factors can be a valuable tool for risk stratification and help identify opportunities for early intervention. Future areas of research include increasing normative data, improving conversion of data between different modalities, and increasing longitudinal studies in children linking childhood risk factors to adult CV outcomes.

Call attention to the role of Beijing Vascular Health Stratification in clinical practice of intellectualized and digital heart and vascular health management medical model in China

Early comprehensive assessment and early intervention of vascular disease, and the life-time maintenance of vascular health are the key to effectively preventing death and disability in end-stage of heart, brain, kidney and peripheral vascular events. Based on this concept, it is necessary to establish a professional clinical discipline of "vascular medicine" which is based on the systemic vascular bed, with measures on prevention, treatment, rehabilitation and intellectualized and digital vascular health management throughout the life cycle for different vascular lesions and different degree of vascular injury. The aim of the establishment of Beijing Vascular Health Stratification (BVHS) is to give a comprehensive and dynamic assessment of vascular health based on the concept of vascular medicine, to conduct individualized analysis of the results, to classify the degree of injury on vascular structure and function, to carry out individualized intervention, and eventually achieve targeted precise prevention and management, establish newly intellectualized and digital vascular health management medical model in China, for effectively reducing the incidence of cardiovascular events.

Arterial pressure pulse wave separation analysis using a multi-Gaussian decomposition model

Objective. Methods for separating the forward–backward components from blood pulse waves rely on simultaneously measured pressure and flow velocity from a target artery site. Modelling approaches for flow velocity simplify the wave separation analysis (WSA), providing a methodological and instrumentational advantage over the former; however, current methods are limited to the aortic site. In this work, a multi-Gaussian decomposition (MGD) modelled WSA (MGDWSA) is developed for a non-aortic site such as the carotid artery. While the model is an adaptation of the existing wave separation theory, it does not rely on the information of measured or modelled flow velocity. Approach. The proposed model decomposes the arterial pressure waveform using weighted and shifted multi-Gaussians, which are then uniquely combined to yield the forward (P F(t)) and backward (P B(t)) pressure wave. A study using the database of healthy (virtual) subjects was used to evaluate the performance of MGDWSA at the carotid artery and was compared against reference flow-based WSA methods. Main results. The MGD modelled pressure waveform yielded a root-mean-square error (RMSE) < 0.35 mmHg. Reliable forward–backward components with a group average RMSE <2.5 mmHg for P F(t) and P B(t) were obtained. When compared with the reference counterparts, the pulse pressures (ΔP F and ΔP B), as well as reflection quantification indices, showed a statistically significant strong correlation (r > 0.96, p < 0.0001) and (r > 0.83, p < 0.0001) respectively, with an insignificant (p > 0.05) bias. Significance. This study reports WSA for carotid pressure waveforms without assumptions on flow conditions. The proposed method has the potential to adapt and widen the vascular health assessment techniques incorporating pulse wave dynamics.

Adiposity-Related Predictors of Vascular Aging From a Life Course Perspective-Findings From the Helsinki Birth Cohort Study.

The main objective of this study was to study predictors of vascular health with focus on adiposity-related factors. Glucose metabolism, blood lipids, inflammatory markers and body composition were assessed 15 years before assessment of vascular health which was assessed with pulse wave velocity (PWV) in 660 subjects born 1934–44. In a univariate analysis in women the strongest association with PWV was seen for age, systolic blood pressure, dysglycemia, dyslipidemia, inflammatory markers and body fat percentage measured in late midlife and PWV measured 15 years later. In men age, body mass index (BMI), systolic blood pressure, dysglycemia, and body fat percentage in late midlife were associated with PWV. One novel finding was that adiposity-related factors were strong predictors of vascular health, something not fully encapsulated in BMI, lean body mass or body fat percentage alone. A higher fat mass index was associated with worse vascular health, which was not ameliorated by a higher lean mass index. Our findings stress the importance to study body composition and fat and lean body mass simultaneously because of their close interaction with each other also in relation to vascular health.

Characterization of the vascular system using overnight wearable-based pulse arrival time and ambulatory blood pressure: A pilot study

Pulse arrival time (PAT) has been broadly investigated for its potential for cuffless blood pressure (BP) estimation and ease of measurement by wearable devices. It is also of great significance to explore whether PAT conveys complementary information to BP for vascular health assessment. In this paper, the differences between the 24-h ambulatory BP and wearable-based PAT were compared among 12 young normotensives and 15 elderly hypertensives in terms of the mean and coefficients of variation (CoVs). The correlations of the nocturnal normalized PAT (n-PAT) and BP with two arterial stiffness-related parameters (i.e., the intrinsic elastic modulus E0 and the vascular modulation factor α) estimated by a proposed model-based method were also compared. The results showed that the inter-subject variances of the nocturnal average n-PAT were significantly different between the hypertensives and the normotensives (P < 0.001), and the intra-subject CoVs of the nocturnal n-PAT were also significantly different between the two groups (P < 0.05). However, these findings were not shown in the nocturnal BP. The correlation coefficient between the nocturnal average n-PAT and ln(E0) is larger than that with the nocturnal BP, i.e., 0.91 vs. 0.56. Furthermore, the result also revealed that all the hypertensives receiving antihypertensive medications did not achieve the optimal control of the nocturnal BP while presented diverse arterial stiffness indicated by the nocturnal average n-PAT and ln(E0). It is concluded that wearable-based PAT contains complementary information about the vascular system to the ambulatory BP, which may be useful for designing effective antihypertensive treatments.

Determinants and Outcomes of Asymptomatic Intracranial Atherosclerotic Stenosis

BackgroundIntracranial atherosclerotic stenosis (ICAS) is one of the most common causes of stroke worldwide and confers a high risk of stroke recurrence, despite aggressive management of risk factors. ObjectivesThis study identified the role of risk factors and risk of vascular events in subjects with asymptomatic ICAS for improved risk stratification. MethodsStroke-free participants in the NOMAS (Northern Manhattan Study), prospectively followed since 1993, underwent a brain magnetic resonance angiogram from 2003 to 2008. The study rated stenosis in 11 brain arteries as: 0: no stenosis; 1: <50% or luminal irregularities; 2: 50%-69%; and 3: ≥70% stenosis or flow gap. The study ascertained vascular events during the post-magnetic resonance imaging (MRI) period. Proportional odds regression quantified the association of pre-MRI exposures, and proportional hazard adjusted models were built to identify the risk of events in the post-MRI period. ResultsThe included sample included 1,211 participants from NOMAS (mean age: 71 ± 9 years; 59% women; 65% Hispanic; 45% had any stenosis). Older age (OR: 1.02 per year; 95% CI: 1.01 to 1.04), hypertension duration (OR: 1.01 per year; 95% CI: 1.00 to 1.02), higher number of glucose-lowering drugs (OR: 1.64 per each medication; 95% CI: 1.24 to 2.15), and high-density lipoprotein (OR: 0.96 per mg/dL; 95% CI: 0.92 to 0.99) were associated with ICAS. The highest event risk was noted among participants with ICAS ≥70% (5.5% annual risk of vascular events; HR: 2.1; 95% CI:1.4 to 3.2; compared with those with no ICAS). ConclusionsICAS is an imaging marker of established atherosclerotic disease in stroke-free subjects, and incidental diagnosis of ICAS should trigger a thorough assessment of vascular health.

Vascular health assessment with flow-mediated dilatation and retinal image analysis: a pilot study in an adult population from Cape Town.

Flow-mediated dilatation (FMD) and retinal vascular analysis (RVA) may assist in predicting cardiovascular disease (CVD) but are poorly characterised in South Africa. We recorded baseline FMD and retinal vascular widths in healthy participants, and investigated associations with cardiovascular risk factors. Endothelial function (measured with FMD), microvascular structure (evaluated via fundus image analysis) and major CVD risk factors were assessed in 66 participants from Cape Town. Median FMD% was 9.6%, with higher values in females. Mean retinal arteriolar and venular widths were ˜156 and ˜250 µm, respectively. FMD was not associated with CVD risk factors. Hypertension was associated with narrower retinal arterioles and venules. We report novel baseline FMD data in healthy South African adults from the Western Cape, and show that retinal microvascular calibres are associated with blood pressure. Our baseline FMD and RVA data could serve as a reference for future studies in South Africa.

Exercise training reduces arterial stiffness in adults with hypertension: a systematic review and meta-analysis.

Arterial stiffness, namely pulse wave velocity (PWV), is an emerging biomarker in the assessment of vascular health. This meta-analysis aims to determine the effects of exercise training on PWV in patients with hypertension, and to identify the possible moderator variables (e.g. type of exercise) of the effect of exercise on PWV. MEDLINE, EMBASE, Cochrane and Web of Science were searched up until July 2019 for randomized controlled trials assessing the effect of exercise interventions lasting 4 or more weeks on PWV in adults with hypertension. Random-effects modelling was used to compare changes from pre to postintervention in PWV between exercise and control groups. Data were reported as weighted mean difference (WMD) and 95% confidence interval (95% CI). Protocol registration: PROSPERO registration number CRD42019138658. We included 14 trials (15 interventions), involving five aerobic, two dynamic resistance, six combined and two isometric resistance groups, totalling 642 participants with hypertension. PWV was significantly reduced by exercise training [(WMD (95% CI) = -0.76 m/s (-1.05 to -0.47)]. Analysis of moderator variables showed that aerobic exercise [WMD (95% CI) = -0.70 m/s (-1.20 to -0.19)], combined exercise [WMD (95% CI) = -0.74 m/s (-1.41 to -0.08)] and isometric resistance exercise [WMD (95% CI) = -0.98 m/s (-1.24 to -0.73)] reduced PWV. There was no significant reduction in PWV in participants undertaking dynamic resistance training [WMD (95% CI) = -0.58 (-1.58 to 0.42)]. This meta-analysis supports that exercise interventions based on aerobic, combined or isometric exercise are suitable to improve PWV in adults with hypertension.

Variable association of 24-h peripheral and central hemodynamics and stiffness with hypertension-mediated organ damage: the VASOTENS Registry.

In this analysis of the telehealth-based Vascular health ASsessment Of The hypertENSive patients Registry, we checked how 24-h central and peripheral hemodynamics compare with hypertension-mediated organ damage (HMOD). In 646 hypertensive patients (mean age 52 ± 16 years, 54% males, 65% treated) we obtained ambulatory brachial and central SBP and pulse pressure (PP), SBP, and PP variability, pulse wave velocity and augmentation index with a validated cuff-based technology. HMOD was defined by an increased left ventricular mass index (cardiac damage, evaluated in 482 patients), an increased intima-media thickness (vascular damage, n = 368), or a decreased estimated glomerular filtration rate or increased urine albumin excretion (renal damage, n = 388). Ambulatory SBP and PPs were significantly associated with cardiac damage: the largest odds ratio was observed for 24-h central SBP [1.032 (1.012, 1.051), P = 0.001] and PP [1.042 (1.015, 1.069), P = 0.002], the weakest for brachial estimates. The association was less strong for vascular damage with a trend to the superiority of 24-h central [1.036 (0.997, 1.076), P = 0.070] over brachial PP [1.031 (1.000, 1.062), P = 0.052]. No statistically significant association was observed for renal damage. SBP and PP variabilities, pulse wave velocity and augmentation index were not associated with any form of HMOD. In the multivariate analysis, age was associated with any type of HMOD, whereas central SBP and PP were predictive of an increased risk of cardiac damage. In hypertensive patients a variable association exists between peripheral and central hemodynamics and various types of HMOD, with the most predictive power being observed for central SBP and PP for cardiac damage.

Vascular Health of Children Conceived via In Vitro Fertilization

To evaluate whether invitro fertilization (IVF) has an effect on the cardiovascular health of offspring. This was a cross-sectional pilot study. We performed vascular health assessment for 17 children aged 10-14years who were conceived via IVF with autologous oocytes at Stanford University. Carotid artery ultrasound evaluated intima-media thickness and stiffness, carotid-femoral pulse wave velocity determined segmental arterial stiffness, and endothelial pulse amplitude testing assessed endothelial function. We compared IVF offspring with control adolescents assessed in the same laboratory, with all comparisons adjusted for age, sex, and race/ethnicity. All participants had normal body mass index and blood pressure. Compared with controls, IVF children had thicker common carotid artery intima-media thickness (0.44±0.03mm vs 0.38±0.03mm; P<.01), higher elastic modulus (395.29±185.33mm Hg vs 242.79±37.69mm Hg; P=.01), higher βstiffness (2.65±0.38 vs 2.28±0.23; P<.01), and higher peak velocity (142.29±31.62cm/s vs 117.71±32.69cm/s; P=.04). The mean endothelial pulse amplitude testing reactive hyperemia index was not significantly different between IVF and controls. The mean pulse wave velocity was 4.69±0.51m/s compared with the controls 4.60±0.57m/s (P=.11), with 8 (47%) having abnormal values. In an assessment of endothelial function and arterial properties of children conceived via IVF, we found that children conceived via IVF seem to have evidence of abnormal vascular health. Further studies with larger sample size and long-term follow-up are warranted.

Ambulatory blood pressure and arterial stiffness web-based telemonitoring in patients at cardiovascular risk. First results of the VASOTENS (Vascular health ASsessment Of The hypertENSive patients) Registry.

The VASOTENS Registry is an international telehealth-based repository of 24-hour ambulatory blood pressure monitorings (ABPM) obtained through an oscillometric upper-arm BP monitor allowing combined estimation of some vascular biomarkers. The present paper reports the results obtained in 1200 participants according to different categories of CV risk. Individual readings were averaged for each recording and 24-hour mean of brachial and aortic systolic (SBP) and diastolic blood pressure (DBP), pulse wave velocity (PWV), and augmentation index (AIx) obtained. Peripheral and central BP, PWVand AIx values were increased in older participants (SBP only) and in case of hypertension (SBP and DBP). BP was lower and PWVand AIx higher in females. PWV was increased and BP unchanged in case of metabolic syndrome. Our results suggest that ambulatory pulse wave analysis in a daily life setting may help evaluate vascular health of individuals at risk for CV disease.

Impact of Melatonin on Vascular Health in Humans

Melatonin, a circadian hormone released from the pineal gland, has recently been recognized to be involved in the pathophysiology of cardiovascular disease. Due to systemic localization of its receptors, melatonin is thought to play an important role in the regulation of vascular function. Data from animal models provide evidence that melatonin is protective against endothelial damage and the subsequent development of atherosclerosis. However, the effects of melatonin on vascular function in humans have yet to be determined.PurposeThe present study tested the hypotheses that, in humans 1) endogenous melatonin production is associated with vascular health and 2) supplemental melatonin improves vascular health.MethodsUpon arrival to the lab, 12 apparently healthy adult men (28±3 y) provided an overnight urine sample to measure 6‐sulfatoxymelatonin, the urine metabolite of melatonin. Subsequently, vascular endothelial function (flow‐mediated dilation; FMD) was assessed. In a follow‐up experiment, a comprehensive assessment of vascular health including brachial arterial blood pressure, FMD, and arterial stiffness (carotid‐femoral pulse wave velocity; PWV) was assessed in 4 individuals (31±6 y) at baseline and 1 hour following a single oral dose of melatonin (5 mg).ResultsFMD (%) was positively associated with total overnight melatonin production (ng; r=0.592, p=0.042) and melatonin excretion rate (ng/hour; r=0.539, p=0.071). Compared with baseline, PWV significantly decreased (5.9±1.3 to 5.7±1.3 m/s, p=0.003) and FMD increased (7.5±2.2 to 8.1±1.8 %, p=0.173) 1 hour following ingestion of supplemental melatonin. Supplemental melatonin did not change blood pressure (114±6 to 114±9 mm Hg, p=0.927).ConclusionThese novel data in humans demonstrate that higher endogenous melatonin production is associated with greater vascular endothelial function. In addition, a single dose of supplemental melatonin is capable of reducing arterial stiffness and improving endothelial function. Together, these findings suggest that melatonin may serve a beneficial role in regulating vascular function in humans. Achieving adequate overnight melatonin production may represent an important therapeutic strategy for the maintenance of optimal vascular health.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

A Dynamic Model of Brain Hemodynamics in Near-Infrared Spectroscopy.

Near-infrared spectroscopy (NiRS) is a noninvasive technology used in measuring oxy- and deoxy-hemoglobin changes, neural activation, functional connectivity, and vascular health assessment. In this paper, we propose a dynamic model of the NiRS signal to facilitate a better understanding of the underlying elements of this signal and as a means of validation for existing and new NiRS signal processing algorithms. The model incorporates arterial pulsations, its possible frequency drifts and the reflected waves, the hemodynamic response function (HRF), Mayer waves, respiratory waves and other very low-frequency components of the NiRS signal. Parameter selection and model fitting have been carried out using measurements from a NiRS database. Our database includes 25 participants each with 64 channels, covering all the scalp and therefore providing realistic measures of the varying parameters. We compared synthetic resting-state and HRF-included model outputs with in vivo resting and task-included measurements. The results showed a significant equivalence of the in vivo and synthetic signals. The proposed signal model generates realistic NiRS signals. The model accepts simple physiological and physical parameters to produce realistic NiRS signals and will accelerate the growth of optical signal processing algorithms.

Effect of exercise order of combined aerobic and resistance training on arterial stiffness in older men.

Arterial stiffness increases with advancing age, and is as an emerging biomarker in the assessment of vascular health. Some studies suggest that high-intensity resistance training increases arterial stiffness, but low- to moderate-intensity resistance training does not effect on arterial stiffening. Current evidence suggests that performing aerobic exercise after resistance training improved arterial stiffness in the young men and women. However, few studies have been conducted on the effects of the order of combined training on arterial stiffness in the elderly. The purpose of this study was to examine the effects of exercise order of combined aerobic and resistance training into the same session on body composition, muscle strength and arterial stiffness in older men. Forty-five older men (aged 70.5 ± 3.5 years) were randomly assigned to 3 groups; AR: aerobic before resistance training, RA: resistance before aerobic training and CON: no training. Subjects trained 2 times per week for 10 weeks. Resistance training consisted of 3 sets of 8-12 repetitions for 5 different exercises, 70-80% of one repetition maximum (1RM). Aerobic exercise consisted of cycling at 60% of heart rate reserve (HRR). Significant interaction effects were observed in waist circumference (P < 0.01), grip strength (P < 0.01), 10-m walk speed (P < 0.05) and 1RM strength (P < 0.01). However, no significant differences were observed between AR and RA. In contrast, pulse wave velocity (PWV) significantly reduced in the RA (9.0 ± 1.6 m/s to 8.0 ± 1.6 m/s, P < 0.05), whereas, it did not change in the AR, and there was a significant group difference (P < 0.05). In conclusion, no effects of the exercise order were observed in body composition, physical fitness and muscle strength. However, aerobic exercise after high-intensity resistance training reduced arterial stiffness and difference of exercise order was observed. We suggest that the exercise order may favorably affect arterial stiffness when combined aerobic exercise and high-intensity resistance training is performed into the same session.

Retinal vascular imaging technology to monitor disease severity and complications in type 1 diabetes mellitus: Asystematic review.

Type 1 diabetes mellitus (T1DM) is a major disease affecting a large number of young patients. In the recent years, retinal vascular imaging has provided an objective assessment of vascular health in patients with T1DM. Our study aimed to review the current literature on retinal vascular parameters in young patients with T1DM in order to understand the following: (i) How retinal vessels are affected in T1DM (ii) How such vascular changes can be predictive of future diabetic microvascular complications METHODS: We performed a systematic review and extracted relevant data from 17 articles. We found significant correlations between retinal vessel changes and diabetes-related risk factors (eg, hypertension, hyperlipidemia, and obesity), diabetes-related features (eg, diabetes duration and glycemic control), and diabetes-related microvascular complications (eg, diabetic retinopathy, nephropathy, and neuropathy). Our findings suggest that retinal microvasculature is associated with both disease severity and complications in young patients with T1DM.

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

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

Vascular Health Assessment of The Hypertensive Patients (VASOTENS) Registry: Study Protocol of an International, Web-Based Telemonitoring Registry for Ambulatory Blood Pressure and Arterial Stiffness.

BackgroundHypertension guidelines recommend ambulatory blood pressure (ABP), central aortic pressure (CAP), and pulse wave velocity (PWV) as parameters for estimating blood pressure (BP) control and vascular impairment. Recent advances in technology have enabled devices to combine non-invasive estimation of these parameters over the 24-hour ABP monitoring. However, currently there is limited evidence on the usefulness of such an approach for routine hypertension management.ObjectiveWe recently launched an investigator-initiated, international, multicenter, observational, prospective study, the Vascular health Assessment Of The Hypertensive patients (VASOTENS) Registry, aimed at (1) evaluating non-invasive 24-hour ABP and arterial stiffness estimates (through 24-hour pulse wave analysis, PWA) in hypertensive subjects undergoing ambulatory blood pressure monitoring (ABPM) for clinical reasons; (2) assessing the changes in estimates following treatment; (3) weighing the impact of 24-hour PWA on target organ damage and cardiovascular prognosis; (4) assessing the relationship between arterial stiffness, BP absolute mean level and variability, and prognosis; and (5) validating the use of a 24-hour PWA electronic health (e-health) solution for hypertension screening.MethodsApproximately 2000 subjects, referred to 20 hypertension clinics for routine diagnostic evaluation and follow-up of hypertension of any severity or stage, will be recruited. Data collection will include ABPM, performed with a device allowing simultaneous non-invasive assessment of 24-hour CAP and arterial stiffness (BPLab), and clinical data (including cardiovascular outcomes). As recommended by current guidelines, each patient will be followed-up with visits occurring at regular intervals (ideally every 6 months, and not less than once a year depending on disease severity). A Web-based telemedicine platform (THOLOMEUS) will be used for data collection. The use of the telemedicine system will allow standardized and centralized data collection, data validation by experts and counseling to remote centers, setup and maintenance of the Registry, and prompt data analysis.ResultsFirst follow-up results are expected to be available in the next 2 years.ConclusionsThe results of the VASOTENS Registry will help define the normalcy thresholds for current and future indices derived from 24-hour PWA, according to outcome data, and will also provide supporting evidence for the inclusion of this type of evaluation in hypertension management.Trial registrationClinicaltrials.gov NCT02577835; https://clinicaltrials.gov/ct2/show/NCT02577835 (Archived by WebCite at http://www.Webcitation.org/6hzZBKY2Q)

Assessment of Vascular Health With Photoplethysmographic Waveforms From the Fingertip.

Although the flow-mediated dilation (FMD) index is considered the most reliable indicator of vascular endothelial function, previous studies have proved that the dilatation index (DI) measured by the highly reproducible air pressure sensing system (APSS) is just as accurate in effectively determining endothelial function. Besides, not only is APSS cheaper than the instrument for FMD ratio measurement, but operation of the former is also simple to facilitate its domestic use. However, APSS had the pitfall of being time consuming because of the large amount of computation involved. This paper attempted to validate a new self-developed endothelial function screening (EFS) device that utilized the photoplethysmography (PPG) system for acquiring PPG waveform signals from the index finger through an infrared sensor and a pressure cuff for applying pressure on ipsilateral upper arm for eliciting reactive hyperemic response to assess vascular health. The mean peak amplitude of the signals during the hyperemic phase was divided by that of the baseline to produce an EFS ratio. About 52 volunteers of age 34.76 ± 15.23years without history of cardiovascular diseases were recruited for vascular endothelial function evaluation using the EFS device and the APSS. Bland-Altman analysis showed good consistency between the EFS ratio and DI. Besides, linear regression analysis demonstrated highly significant correlation between the two sets of data (p < 0.001, r2 = 0.6261) In conclusion, this paper, which attempted to validate a self-developed, economical, and time-efficient device that can be operated in a domestic setting, demonstrated that the EFS device yielded consistent results on vascular endothelial function comparable to those acquired through APSS.