The aging of elastic and muscular arteries: a comparison of diabetic and nondiabetic subjects

Structural and Mechanical Properties of Human Superficial Femoral and Popliteal Arteries

The femoropopliteal artery (FPA) is the main artery in the lower limb. It supplies blood to the leg muscles and undergoes complex deformations during limb flexion. Atherosclerotic disease of the FPA (peripheral arterial disease, PAD) is a major public health burden, and despite advances in surgical and interventional therapies, the clinical outcomes of PAD repairs continue to be suboptimal, particularly in challenging calcified lesions and biomechanically active locations. A better understanding of human FPA mechanical and structural characteristics in relation to age, risk factors, and the severity of vascular disease can help develop more effective and longer-lasting treatments through computational modeling and device optimization. This review aims to summarize recent research on the main biomechanical and structural properties of human superficial femoral and popliteal arteries that comprise the FPA and describe their anatomy, composition, and mechanical behavior under different conditions.

Mechanical, structural, and physiologic differences between above and below-knee human arteries

Peripheral Artery Disease (PAD) affects the lower extremities and frequently results in poor clinical outcomes, especially in the vessels below the knee. Understanding the biomechanical and structural characteristics of these arteries is important for improving treatment efficacy, but mechanical and structural data on tibial vessels remain limited. We compared the superficial femoral (SFA) and popliteal (PA) arteries that comprise the above-knee femoropopliteal (FPA) segment to the infrapopliteal (IPA) anterior tibial (AT), posterior tibial (PT), and fibular (FA) arteries from the same 15 human subjects (average age 52, range 42-67 years, 87 % male). Vessels were imaged using μCT, evaluated with biaxial mechanical testing and constitutive modeling, and assessed for elastin, collagen, smooth muscle cells (SMCs), and glycosaminoglycans (GAGs). IPAs were more often diseased or calcified compared to the FPAs. They were also twice smaller, 53 % thinner, and significantly stiffer than the FPA longitudinally, but not circumferentially. IPAs experienced 48 % higher physiologic longitudinal stresses (62 kPa) but 27 % lower circumferential stresses (24 kPa) and similar cardiac cycle stretch of <1.02 compared to the FPA. IPAs had lower longitudinal pre-stretch (1.12) than the FPAs (1.29), but there were no differences in the stored elastic energy during pulsation. The physiologic circumferential stiffness was similar in the above and below-knee arteries (718 kPa vs 754 kPa). Structurally, IPAs had less elastin, collagen, and GAGs than the FPA, but maintained similar SMC content. Our findings contribute to a better understanding of segment-specific human lower extremity artery biomechanics and may inform the development of better medical devices for PAD treatment. STATEMENT OF SIGNIFICANCE: Peripheral Artery Disease (PAD) in the lower extremity arteries exhibits distinct characteristics and results in different clinical outcomes when treating arteries above and below the knee. However, their mechanical, structural, and physiologic differences are poorly understood. Our study compared above- and below-knee arteries from the same middle-aged human subjects and demonstrated distinct differences in size, structure, and mechanical properties, leading to variations in their physiological behavior. These insights could pave the way for creating location-specific medical devices and treatments for PAD, offering a more effective approach to its management. Our findings provide new, important perspectives for clinicians, researchers, and medical device developers interested in treating PAD in both above- and below-knee locations.

Arterial Stiffness and Obesity as Predictors of Diabetes: Longitudinal Cohort Study

BACKGROUND

Previous studies have confirmed the separate effect of arterial stiffness and obesity on type 2 diabetes; however, the joint effect of arterial stiffness and obesity on diabetes onset remains unclear.

OBJECTIVE

This study aimed to propose the concept of arterial stiffness obesity phenotype and explore the risk stratification capacity for diabetes.

METHODS

This longitudinal cohort study used baseline data of 12,298 participants from Beijing Xiaotangshan Examination Center between 2008 and 2013 and then annually followed them until incident diabetes or 2019. BMI (waist circumference) and brachial-ankle pulse wave velocity were measured to define arterial stiffness abdominal obesity phenotype. The Cox proportional hazard model was used to estimate the hazard ratio (HR) and 95% CI.

RESULTS

Of the 12,298 participants, the mean baseline age was 51.2 (SD 13.6) years, and 8448 (68.7%) were male. After a median follow-up of 5.0 (IQR 2.0-8.0) years, 1240 (10.1%) participants developed diabetes. Compared with the ideal vascular function and nonobese group, the highest risk of diabetes was observed in the elevated arterial stiffness and obese group (HR 1.94, 95% CI 1.60-2.35). Those with exclusive arterial stiffness or obesity exhibited a similar risk of diabetes, and the adjusted HRs were 1.63 (95% CI 1.37-1.94) and 1.64 (95% CI 1.32-2.04), respectively. Consistent results were observed in multiple sensitivity analyses, among subgroups of age and fasting glucose level, and alternatively using arterial stiffness abdominal obesity phenotype.

CONCLUSIONS

This study proposed the concept of arterial stiffness abdominal obesity phenotype, which could improve the risk stratification and management of diabetes. The clinical significance of arterial stiffness abdominal obesity phenotype needs further validation for other cardiometabolic disorders.

Vascular Aging: Assessment and Intervention

Vascular aging represents a collection of structural and functional changes in a blood vessel with advancing age, including increased stiffness, vascular wall remodeling, loss of angiogenic ability, and endothelium-dependent vasodilation dysfunction. These age-related alterations may occur earlier in those who are at risk for or have cardiovascular diseases, therefore, are defined as early or premature vascular aging. Vascular aging contributes independently to cardio-cerebral vascular diseases (CCVDs). Thus, early diagnosis and interventions targeting vascular aging are of paramount importance in the delay or prevention of CCVDs. Here, we review the direct assessment of vascular aging by examining parameters that reflect changes in structure, function, or their compliance with age including arterial wall thickness and lumen diameter, endothelium-dependent vasodilation, arterial stiffness as well as indirect assessment through pathological studies of biomarkers including endothelial progenitor cell, lymphocytic telomeres, advanced glycation end-products, and C-reactive protein. Further, we evaluate how different types of interventions including lifestyle mediation, such as caloric restriction and salt intake, and treatments for hypertension, diabetes, and hyperlipidemia affect age-related vascular changes. As a single parameter or intervention targets only a certain vascular physiological change, it is recommended to use multiple parameters to evaluate and design intervention approaches accordingly to prevent systemic vascular aging in clinical practices or population-based studies.

Decreased Diastolic Blood Pressure and Average Grip Strength in Adults With Type 1 Diabetes Compared With Controls: An Analysis of Data From the Canadian Longitudinal Study on Aging

OBJECTIVES

Our aim in this study was to determine whether aging individuals with type 1 diabetes (T1D) have differences in cardiovascular health, assessed by blood pressure, and skeletal muscle function, assessed by grip strength, compared with matched nondiabetic controls (CON).

METHODS

This investigation was a retrospective cohort analysis using baseline and 3-year follow-up data from the Canadian Longitudinal Study on Aging. Bivariate and multivariate regression analyses were used to examine the association between sociodemographic, health, behavioural and T1D-specific variables on blood pressure and grip strength in T1D and CON groups. Generalized estimating equations were used to model the average population changes in blood pressure and grip strength from baseline to follow up.

RESULTS

The sample included 126 individuals (63 T1D and 63 CON). Systolic blood pressure was not significantly different between groups at baseline or follow up (p>0.05). However, compared with CON, diastolic blood pressure was significantly lower at both time-points in the T1D group (p<0.001). Grip strength was consistently lower among persons with T1D (p=0.03). In the multivariate regression model, body mass index, age and sex were significantly associated with diastolic blood pressure and grip strength in both groups. In the T1D group, disease duration accounted for a large proportion of the variance in diastolic blood pressure and grip strength (17% and 9%, respectively). The rate of decline in diastolic blood pressure and grip strength did not differ between groups (p>0.05).

CONCLUSIONS

Diastolic blood pressure and grip strength appear to be consistently lower and differentially regulated in individuals with T1D vs CON. Aging individuals with T1D may be at risk of premature morbidity and mortality.

Measurement of wave propagation through a tube using dual transducers for elastography in arteries

Objective.Measuring waves induced with acoustic radiation force (ARF) in arteries has been studied over the last decade. To date, it remains a challenge to quantitatively assess the local arterial biomechanical properties. The cylindrical shape and waveguide behavior of waves propagating in the arterial wall pose complexities to determining the mechanical properties of the artery.Approach. In this paper, an artery-mimicking tube in water is examined utilizing three-dimensional measurements. The cross-section of the tube is measured while a transducer is translated over 41 different positions along the length of the tube. Motion in the radial direction is calculated using two components of motion which are measured from the two orthogonal views of the cross-section. This enables more accurate estimation of motion along the circumference of tube.Main results. The results provide more information to categorize the motion in tube wall into two types of responses: a transient response and a steady state response. The transient response is caused by ARF application and the waves travel along the length of the tube for a relatively short period of time. This corresponds to the axial and circumferential propagating waves. The two circumferential waves travel along the circumference of tube in CW (clockwise) and CCW (counter-clockwise) direction and result in a standing wave. By using a directional filter, the two waves were successfully separated, and their propagation was more clearly visualized. As a steady state response, a circumferential mode is generated showing a symmetric motion (i.e. the proximal and distal walls move in the opposite direction) following the transient response.Significance.This study provides a more comprehensive understanding of the waves produced in an artery-mimicking tube with ARF application, which will provide opportunities for improving measurement of arterial mechanical properties.

Connecting Aortic Stiffness to Vascular Contraction: Does Sex Matter?

This study was designed to connect aortic stiffness to vascular contraction in young male and female Wistar rats. We hypothesized that female animals display reduced intrinsic media-layer stiffness, which associates with improved vascular function. Atomic force microscopy (AFM)-based nanoindentation analysis was used to derive stiffness (Young’s modulus) in biaxially (i.e., longitudinal and circumferential) unloaded aortic rings. Reactivity studies compatible with uniaxial loading (i.e., circumferential) were used to assess vascular responses to a selective α1 adrenergic receptor agonist in the presence or absence of extracellular calcium. Elastin and collagen levels were indirectly evaluated with fluorescence microscopy and a picrosirius red staining kit, respectively. We report that male and female Wistar rats display similar AFM-derived aortic media-layer stiffness, even though female animals withstand higher aortic intima-media thickness-to-diameter ratio than males. Female animals also present reduced phenylephrine-induced aortic force development in concentration-response and time-force curves. Specifically, we observed impaired force displacement in both parts of the contraction curve (Aphasic and Atonic) in experiments conducted with and without extracellular calcium. Additionally, collagen levels were lower in female animals without significant elastin content and fragmentation changes. In summary, sex-related functional differences in isolated aortas appear to be related to dissimilarities in the dynamics of vascular reactivity and extracellular matrix composition rather than a direct response to a shift in intrinsic media-layer stiffness.

Hypertension, Arterial Stiffness, and Diabetes: a Prospective Cohort Study

Whether the combination of different blood pressure and arterial stiffness (AS) status is independently associated with diabetes has not been fully investigated so far. This study aimed at investigating the status of hypertension and AS in determining diabetes.

Arterial Stiffness, Genetic Risk, and Type 2 Diabetes: A Prospective Cohort Study

OBJECTIVE

We aimed to investigate prospective associations of pulse wave arterial stiffness index (ASI) and pulse pressure (PP) with type 2 diabetes (T2D) and assess the modifying effect of genetics.

RESEARCH DESIGN AND METHODS

We included 152,611 participants free of diabetes and cardiovascular disease in the UK Biobank. All participants had ASI and blood pressure measurements collected at baseline visit. In total, 37 single nucleotide polymorphisms were used to calculate the genetic risk score (GRS) of T2D.

RESULTS

During a median follow-up of 9.5 years, 3,000 participants developed T2D. Per-SD increase in ASI was associated with a 3% higher T2D risk (95% CI 2-4%). The hazard ratio (HR) (95% CI) of T2D was 1.58 (1.39-1.80) in the highest quintile group compared with the lowest quintile group of ASI. However, the association between PP and T2D was nonlinear. Compared with the lowest quintile group, the risk of T2D in higher quintile groups of PP was 0.91 (0.79-1.04), 0.98 (0.86-1.11), 1.15 (1.01-1.30), and 1.24 (1.10-1.41), respectively. Furthermore, we observed an interaction between ASI and genetic susceptibility to T2D, because the elevated HR of T2D associated with high ASI was more evident among participants with higher GRS of T2D (P interaction = 0.008), whereas the interaction between PP and GRS was nonsignificant (P interaction = 0.55).

CONCLUSIONS

ASI was associated with an elevated risk of T2D in a dose-response fashion, whereas PP and T2D showed a nonlinear J-shaped association. Additionally, the association between ASI and T2D was partially strengthened by higher genetic susceptibility to T2D.

Diabetes mellitus is associated with worse baseline and less post-treatment recovery of arterial stiffness in patients with primary aldosteronism

Background:

Aldosterone excess in primary aldosteronism (PA) has been linked to insulin resistance, and diabetes mellitus has been associated with increased arterial stiffness and worse cardiovascular outcomes. However, the impact of diabetes on baseline and post-treatment arterial stiffness in patients with PA is unknown.

Methods:

This study prospectively enrolled 1071 PA patients, of whom 177 had diabetes and 894 did not. Clinical, biochemical, and brachial-ankle pulse wave velocity (baPWV) data were analyzed at baseline and 1 year after PA-specific treatment. After propensity score matching of age, sex, body mass index, systolic and diastolic blood pressure, hypertension duration, and number of antihypertensive medications, 144 patients with diabetes and 320 without diabetes were included for further analysis.

Results:

After propensity score matching, the baseline characteristics were balanced between the diabetes and nondiabetes groups except for fasting glucose, HbA1c, and lipid profiles. The patients with diabetes had significantly worse baseline baPWV compared with those without diabetes. After multivariable linear regression, the presence of diabetes mellitus remained a significant predictor of worse baseline mean baPWV (β: 46.3, 95% confidence interval: 2.9–89.7, p = 0.037). After 1 year of PA-specific treatment, only the nondiabetes group had significant recovery of mean baPWV (1661.8 ± 332.3 to 1565.0 ± 329.2 cm/s, p < 0.001; Δ = −96.8 ± 254.6 cm/s). In contrast, the diabetes group had less improvement (1771.2 ± 353.8 cm/s to 1742.0 ± 377.2 cm/s, p = 0.259; Δ = −29.2 ± 263.2 cm/s) even though the systolic and diastolic blood pressure significantly improved in both groups.

Conclusion:

The presence of diabetes mellitus in PA patients was associated with worse baseline and less post-treatment recovery of arterial stiffness.

Vascular Stiffness in Aging and Disease

The goal of this review is to provide further understanding of increased vascular stiffness with aging, and how it contributes to the adverse effects of major human diseases. Differences in stiffness down the aortic tree are discussed, a topic requiring further research, because most prior work only examined one location in the aorta. It is also important to understand the divergent effects of increased aortic stiffness between males and females, principally due to the protective role of female sex hormones prior to menopause. Another goal is to review human and non-human primate data and contrast them with data in rodents. This is particularly important for understanding sex differences in vascular stiffness with aging as well as the changes in vascular stiffness before and after menopause in females, as this is controversial. This area of research necessitates studies in humans and non-human primates, since rodents do not go through menopause. The most important mechanism studied as a cause of age-related increases in vascular stiffness is an alteration in the vascular extracellular matrix resulting from an increase in collagen and decrease in elastin. However, there are other mechanisms mediating increased vascular stiffness, such as collagen and elastin disarray, calcium deposition, endothelial dysfunction, and the number of vascular smooth muscle cells (VSMCs). Populations with increased longevity, who live in areas called “Blue Zones,” are also discussed as they provide additional insights into mechanisms that protect against age-related increases in vascular stiffness. Such increases in vascular stiffness are important in mediating the adverse effects of major cardiovascular diseases, including atherosclerosis, hypertension and diabetes, but require further research into their mechanisms and treatment.

Determination of aortic pulse transit time based on waveform decomposition of radial pressure wave

Carotid-femoral pulse transit time (cfPTT) is a widely accepted measure of central arterial stiffness. The cfPTT is commonly calculated from two synchronized pressure waves. However, measurement of synchronized pressure waves is technically challenging. In this paper, a method of decomposing the radial pressure wave is proposed for estimating cfPTT. From the radial pressure wave alone, the pressure wave can be decomposed into forward and backward waves by fitting a double triangular flow wave. The first zero point of the second derivative of the radial pressure wave and the peak of the dicrotic segment of radial pressure wave are used as the peaks of the fitted double triangular flow wave. The correlation coefficient between the measured wave and the estimated forward and backward waves based on the decomposition of the radial pressure wave was 0.98 and 0.75, respectively. Then from the backward wave, cfPTT can be estimated. Because it has been verified that the time lag estimation based on of backward wave has strong correlation with the measured cfPTT. The corresponding regression function between the time lag estimation of backward wave and measured cfPTT is y = 0.96x + 5.50 (r = 0.77; p < 0.001). The estimated cfPTT using radial pressure wave decomposition based on the proposed double triangular flow wave is more accurate and convenient than the decomposition of the aortic pressure wave based on the triangular flow wave. The significance of this study is that arterial stiffness can be directly estimated from a noninvasively measured radial pressure wave.

Diabetes, metabolic disease, and telomere length

Telomeres are regions of repetitive nucleotide sequences at the ends of chromosomes. Telomere length is a marker of DNA damage, which is often considered a biomarker for biological ageing, and has also been linked with cardiovascular disease, diabetes, and cancer. Emerging studies have highlighted the role of genetic and environmental factors, and explored the effect of modulating telomere length. We provide an overview of studies to date on diabetes and telomere length, and compare different methods and assays for evaluating telomere length and telomerase activity. We highlight the limitations of current studies and areas that warrant further research to unravel the link between diabetes and telomere length. The value of adding telomere length to clinical risk factors to improve risk prediction of diabetes and related complications also merits further investigation.

Role of arterial stiffness in the association between hand grip strength and cardiovascular events: the Korean Genome and Epidemiology Study

BACKGROUND

Hand grip strength (HGS) has been associated with cardiovascular events. However, the exact mechanism responsible for the inverse association between HGS and cardiovascular events has not been established. The aim of this study was to assess whether arterial stiffness mediates this association.

METHODS

We studied 1508 participants (age; 60 ± 5, men; 47.5%) from the Ansan cohort of the Korean Genome Epidemiology Study. Participants were assessed for various parameters of arterial stiffness as well as HGS. The augmentation index (AIx) and brachial-ankle pulse wave velocity (baPWV) were evaluated by using an applanation tonometer and automated waveform analyzer, respectively. Carotid intima medial thickness (IMT) was measured by B-mode ultrasonogram with a 7.5-MHz linear array transducer. HGS was evaluated using a Jamar dynamometer.

RESULTS

With increased grip strength, AIx decreased (r = 0.437, P < 0.001). baPWV (r = 0.044, P = 0.107) and carotid IMT (r = 0.005, P = 0.856) had no significant correlation with grip strength. This trend was consistently observed regardless of hypertension, but was more pronounced in participants with hypertension.

CONCLUSION

HGS was significantly correlated with AIx, but not with baPWV and carotid IMT. Our findings suggest that central arterial stiffness could mediate the association between HGS and cardiovascular events.

Mechanical, structural, and physiologic differences in human elastic and muscular arteries of different ages: Comparison of the descending thoracic aorta to the superficial femoral artery

Elastic and muscular arteries differ in structure, function, and mechanical properties, and may adapt differently to aging. We compared the descending thoracic aortas (TA) and the superficial femoral arteries (SFA) of 27 tissue donors (average 41±18 years, range 13-73 years) using planar biaxial testing, constitutive modeling, and bidirectional histology. Both TAs and SFAs increased in size with age, with the outer radius increasing more than the inner radius, but the TAs thickened 6-fold and widened 3-fold faster than the SFAs. The circumferential opening angle did not change in the TA, but increased 2.4-fold in the SFA. Young TAs were relatively isotropic, but the anisotropy increased with age due to longitudinal stiffening. SFAs were 51% more compliant longitudinally irrespective of age. Older TAs and SFAs were stiffer, but the SFA stiffened 5.6-fold faster circumferentially than the TA. Physiologic stresses decreased with age in both arteries, with greater changes occurring longitudinally. TAs had larger circumferential, but smaller longitudinal stresses than the SFAs, larger cardiac cycle stretch, 36% lower circumferential stiffness, and 8-fold more elastic energy available for pulsation. TAs contained elastin sheets separated by smooth muscle cells (SMCs), collagen, and glycosaminoglycans, while the SFAs had SMCs, collagen, and longitudinal elastic fibers. With age, densities of elastin and SMCs decreased, collagen remained constant due to medial thickening, and the glycosaminoglycans increased. Elastic and muscular arteries demonstrate different morphological, mechanical, physiologic, and structural characteristics and adapt differently to aging. While the aortas remodel to preserve the Windkessel function, the SFAs maintain higher longitudinal compliance.

Effect of Glycation on Interlamellar Bonding of Arterial Elastin

BACKGROUND

Interlamellar bonding in the arterial wall is often compromised by cardiovascular diseases. However, several recent nationwide and hospital-based studies have uniformly reported reduced risk of thoracic aortic dissection in patients with diabetes. As one of the primary structural constituents in the arterial wall, elastin plays an important role in providing its interlamellar structural integrity.

OBJECTIVE

The purpose of this study is to examine the effects of glycation on the interlamellar bonding properties of arterial elastin.

METHODS

Purified elastin network was isolated from porcine descending thoracic aorta and incubated in 2 M glucose solution for 7, 14 or 21 days at 37 °C. Peeling and direct tension tests were performed to provide complimentary information on understanding the interlamellar layer separation properties of elastin network with glycation effect. Peeling tests were simulated using a cohesive zone model (CZM). Multiphoton imaging was used to visualize the interlamellar elastin fibers in samples subjected to peeling and direct tension.

RESULTS

Peeling and direct tension tests show that interlamellar energy release rate and strength both increases with the duration of glucose treatment. The traction at damage initiation estimated for the CZM agrees well with the interlamellar strength measurements from direct tension tests. Glycation was also found to increase the interlamellar failure strain of arterial elastin. Multiphoton imaging confirmed the contribution of radially running elastin fibers to resisting dissection.

CONCLUSIONS

Nonenzymatic glycation reduces the propensity of arterial elastin to dissection. This study also suggests that the CZM effectively describes the interlamellar bonding properties of arterial elastin.

New Insight into the Mechanisms of Ginkgo Biloba Extract in Vascular Aging Prevention

BACKGROUND

Aging-associated vascular dysfunction promotes cardiovascular diseases. Recently, Ginkgo biloba extract (GBE) has attracted considerable attention in the prevention of aged vasculature.

METHODS

This review discusses the pathophysiological alterations in aged vasculature and the underlying mechanisms of GBE in vascular aging suppression.

RESULTS

Both arterial stiffening and endothelial dysfunction are critical aging-related vascular phenotypes that result in the progression of cardiovascular diseases in the general population. Consistent oxidative stress and inflammatory reaction lead to vascular dysfunction. GBE ameliorates aging-related vascular dysfunction, due to its antioxidant and anti-inflammatory properties. The main effects of GBE in aged vasculature might be associated with the longevity signaling pathways. GBE also attenuates the progression of vascular aging in diabetes mellitus via regulation of glucose and lipid metabolism.

CONCLUSION

GBE plays an important role in the prevention of vascular aging process. It is a promising therapeutic approach to ameliorate aging-related vascular dysfunction and cardiovascular diseases.

Arterial Stiffness Preceding Diabetes: A Longitudinal Study

RATIONALE

Previous studies on the relationship between diabetes and arterial stiffness were mostly cross-sectional. A few longitudinal studies focused on one single direction. Whether the association between arterial stiffness and diabetes is bidirectional remains unclear to date.

OBJECTIVE

To explore the temporal relationship between arterial stiffness and fasting blood glucose (FBG) status.

METHODS AND RESULTS

Included were 14 159 participants of the Kailuan study with assessment of brachial-ankle pulse wave velocity (baPWV) from 2010 to 2015, and free of diabetes, cardiovascular and cerebrovascular diseases, and chronic kidney disease at baseline. FBG and baPWV were repeatedly measured at baseline and follow-ups. Cox proportional hazard regression model was used to estimate hazard ratios and 95% confidence intervals (CIs) of incident diabetes across baseline baPWV groups: <1400 cm/s (ref), 1400≤ baPWV <1800 cm/s, and ≥1800 cm/s. Path analysis was used to analyze the possible temporal causal relationship between baPWV and FBG, among 8956 participants with repeated assessment of baPWV and FBG twice in 2010 to 2017. The mean baseline age of the observed population was 48.3±12.0 years. During mean 3.72 years of follow-up, 979 incident diabetes cases were identified. After adjusting for potential confounders, the hazard ratio (95% CI) for risk of diabetes was 1.59 (1.34-1.88) for the borderline arterial stiffness group and 2.11 (1.71-2.61) for the elevated arterial stiffness group, compared with the normal ideal arterial stiffness group. In the path analysis, baseline baPWV was associated with follow-up FBG (the standard regression coefficient was 0.09 [95% CI, 0.05-0.10]). In contrast, the standard regression coefficient of baseline FBG for follow-up baPWV (β=0.00 [95% CI, -0.02 to 0.02]) was not significant.

CONCLUSIONS

Arterial stiffness, as measured by baPWV, was associated with risk of developing diabetes. Arterial stiffness appeared to precede the increase in FBG.

Common carotid pulsatility is deteriorated by autoimmune thyroiditis in children with type 1 diabetes mellitus - A pilot study

Autoimmune thyroiditis (AIT) frequently coexists with type 1 diabetes (DM1) and additionally increases the extent of microcirculatory complications due to DM1. We hypothesized that in pediatric patients with DM1, impairment of macrocirculation could be further augmented by a coexisting autoimmune process. Therefore, we investigated the influence of AIT on large arteries in DM1 pediatric patients. Our group consisted of 19 DM1, 19 DM1 + AIT patients and 29 control subjects. The groups were comparable regarding age and gender. The DM1 and DM1 + AIT patients were matched for age at onset of DM1 and diabetes duration. Macrocirculation was described using pulsatility indices (PIs) determined for common carotid (CCA) and peripheral arteries of upper and lower limbs. CCA resistance index (RI) and ABI were also assessed. Children with DM1 + AIT had only significantly lower CCA_PI and CCA_RI in comparison with controls whereas in the absence of AIT such difference was not found. The diabetes duration and age of onset did not correlate with carotid indices. Total cholesterol level was higher both in DM1 + AIT and DM1 groups than in the control group. For low density lipoproteins cholesterol, a significant difference was found between DM1 + AIT and control groups. Age-independent impact of AIT on CCA_PI was confirmed by multivariate analysis. Common carotid pulsatility is deteriorated by autoimmune thyroiditis independently of age in children with type 1 diabetes mellitus.

Characteristics of Harmonic Indexes of the Arterial Blood Pressure Waveform in Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is an important public health issue worldwide. T2DM correlates with cardiovascular disease. Arterial stiffness is also a key factor that can be thought of as a surrogate marker. Nevertheless, it was unclear which harmonic indexes of blood pressure waveforms (BPWs) from subjects' radial artery pulses would be affected by T2DM. Therefore, the objective of this study was to investigate whether and how harmonic indexes can be used to discriminate hemodynamic differences between patients with T2DM and non-T2DM. This helps us to build objective results no matter who conducts the examination instead of pulse diagnosis in traditional way. We enrolled T2DM and non-T2DM patients as experimental and control groups, respectively, from the Department of Family Medicine in the National Taiwan University Hospital and the Department of Internal Medicine in Taipei's Veterans General Hospital from December 2017 to January 2019. ANSWatch® Model TS-0411 was used to capture the BPWs. Amplitude proportions (C_n values) were calculated from harmonics 1-10 of the BPW using fast Fourier transform. Thirty-two T2DM and 15 non-T2DM patients were enrolled. T2DM patients had significant differences in C₁ (p = 0.031) and C₅ (p = 0.041). The study suggests that analyzing the harmonic characteristics of non-invasively measured BPW of radial artery may be a potential and easy-to-perform approach to discriminate T2DM-induced hemodynamic changes.

High pulse wave velocity is associated with the severity of diabetic retinopathy in patients with type 2 diabetes

Pulse wave velocity (PWV) is a non-invasive test for assessing arterial stiffness, and brachial-ankle PWV has been used as an index of peripheral arterial stiffness. This study aimed to investigate the association between the PWV value and severity of diabetic retinopathy (DR). 846 patients with type 2 diabetes (T2DM) consecutively underwent brachial-ankle PWV, and the degree of PWV was defined by tertile. The severity of DR was categorized as no diabetic retinopathy (NDR), non-proliferative diabetic retinopathy (NPDR) or proliferative diabetic retinopathy (PDR) based on the Early Treatment Diabetic Retinopathy Study Scale. Multinomial logistic regression analyses were utilized not only to explore the association between the degree of PWV and severity of DR but also to examine the association of a high-tertile PWV with PDR. PWV levels, diabetes duration and blood pressure were all significantly higher in subjects with NPDR or PDR as compared with individuals with NDR. In the univariate analysis, the highest tertile of PWV (>19.6 m/s) was significantly associated with both NPDR (p<0.001) and PDR (p<0.001) as compared with NDR. After adjusting for confounding factors, the highest tertile of PWV remained significantly associated with PDR (p=0.005), but not with NPDR (p=0.107). Furthermore, the highest tertile of PWV was more significantly associated with PDR (OR=6.15, 95%CI 1.38 to 27.38) as compared with the lowest tertile. In our study, an increasing degree of PWV was positively associated with the severity of DR. High PWV was strongly associated with the risk of severe DR, especially PDR.

Endothelial dysfunction and impaired arterial wall properties in patients with retinal vein occlusion

Retinal vein occlusion (RVO) is a common retinal vascular lesion, and a leading cause of visual impairment. Patients with RVO have an increased risk for cardiovascular disease and share multiple common risk factors. In this study, we investigated the endothelial function and arterial stiffness of patients with RVO compared to healthy-control (CL) subjects. We enrolled 40 consecutive patients with RVO and 40 CL subjects. RVO was diagnosed by an ophthalmologist, endothelial function was evaluated by flow mediated dilation (FMD) in the brachial artery, and carotid-femoral pulse wave velocity (PWV) and augmentation index (AIx) of the radial artery were measured to evaluate arterial stiffness and reflected waves, respectively. No significant differences were detected between the studied groups in sex, age, presence of hypertension or dyslipidemia, body mass index, systolic and diastolic blood pressure levels, total cholesterol levels, and smoking habits (p > 0.05 for all). However, patients with RVO had impaired FMD (p = 0.002) and increased PWV (p = 0.004), even after adjustment for several confounders. Both FMD and PWV were also significantly and independently associated with the development of RVO. Furthermore, a significant and positive correlation between PWV and systolic blood pressure existed only in the CL group. Therefore, we have shown that RVO is associated with significant endothelial dysfunction and increased arterial stiffness. Our results strengthen the vascular theory, according to which, systemic endothelial dysfunction and arteriosclerosis play a significant role in the pathogenesis of RVO.

Stiffening and ventricular-arterial interaction in the ascending aorta using MRI: ageing effects in healthy humans

Supplemental Digital Content is available in the text

Objectives:

The aim of this study was to investigate the effect of age and sex on _nPWV and _ndI in the ascending aorta of healthy humans.

Background:

Local pulse wave velocity (_nPWV) and wave intensity (_ndI) in the human ascending aorta have not been studied adequately, because of the need for invasive pressure measurements. However, a recently developed technique made the noninvasive determination of _nPWV and _ndI possible using measurements of flow velocity and arterial diameter.

Methods:

Diameter and flow velocity were measured at the level of the ascending aorta in 144 healthy participants (aged 20–77 years, 66 men), using MRI. _nPWV, _ndI parameters; forward (FCW); backward (BCW) compression waves, forward decompression wave (FDW), local aortic distensibility (_nD_s) and reflection index (_nRI) were calculated.

Results:

_nPWV increased significantly with age from 4.7 ± 0.3 m/s for those 20–30 years to 6.4 ± 0.2 m/s for those 70–80 years (P < 0.001) and did not differ between sexes. _nD_s decreased with age (5.3 ± 0.5 vs. 2.6 ± 0.2 10⁻⁵ 1/Pa, P < 0.001) and _nRI increased with age (0.17 ± 0.03 vs. 0.39 ± 0.06, P < 0.01) for those 20–30 and 70–80 years, respectively. FCW, BCW and FDW decreased significantly with age by 86.3, 71.3 and 74.2%, respectively (P < 0.001), all compared to the lowest age-band.

Conclusion:

In healthy humans, ageing results in stiffer ascending aorta, with increase in _nPWV and decrease in _nD_s. A decrease in FCW and FDW indicates decline in left ventricular early and late systolic functions with age in healthy humans with no differences between sexes. _nRI is more sensitive than BCW in establishing the effects of ageing on reflected waves measured in the ascending aorta.

Normal tolerance limits for side-to-side differences in diameters of major lower limbs arteries of 228 healthy subjects

PURPOSE

To determine reference values and tolerance limits of between-side differences for the calibers of the common femoral artery (CFA), superficial femoral artery (SFA), popliteal artery (PA), dorsalis pedis artery (DPA), and posterior tibial artery (PTA).

MATERIALS AND METHODS

Calibers of arteries, defined as the largest distance between internal hyperechogenic lines of the intima-media complex of the arterial wall, were measured during the diastole phase determined from echo-tracking B mode ultrasound scanning and grey-scale ultrasound in 228 healthy volunteers aged 18-81 years (43.1 ± 16.7).

RESULTS

The mean, 95% confidence and tolerance limits covering 90% of population for left and right side of each artery were: CFA: 8.1 mm, 7.9-8.3 mm, 6.0-10.3 mm; 8.1 mm, 7.9-8.5 mm, 5.9-10.2 mm; SFA: 6.2 mm, 6.0-6.3 mm, 4.7-7.6 mm; 6.1 mm, 6.0-6.3 mm, 4.7-7.6 mm; PA: 6.1 mm, 6.0-6.2 mm, 4.6-7.6 mm; 6.1 mm, 5.9-6.2 mm, 4.5-7.6 mm; DPA: 2.0 mm, 1.9-2.0 mm, 1.2-2.7 mm; 2.0 mm, 1.9-2.0 mm, 1.2-2.8 mm; PTA: 2.1 mm, 2.0-2.1 mm, 1.4-2.8 mm; 2.1 mm, 2.1-2.2 mm, 1.4-2.8 mm, respectively. Tolerance limits for between-side differences and ratios were: CFA - 0.5-0.7 mm, 0.9-1.1; SFA - 0.5-0.6 mm, 0.9-1.1; PA - 0.5-0.5 mm, 0.9-1.1; DPA -0.4-0.4 mm, 0.8-1.2; PTA - 0.4-0.4 mm, 0.8-1.2. Regression analysis showed weight and age dependency of vessels diameters. There are no differences between men and woman in vessels size, except in DPA's, when body weight and age are taken into account in a regression analysis.

CONCLUSIONS

We estimated normal reference tolerance limits of side-to-side differences in diameters of lower limb arteries. The limits can inform an investigator what differences in diameters occur in healthy individuals, and hence can serve as cut-offs in diagnostic and screening strategies.

Cardiometabolic Health and Carotid-Femoral Pulse Wave Velocity in Children: A Systematic Review and Meta-Regression

OBJECTIVE

To identify, in children the normal rate of carotid-femoral pulse wave velocity (cfPWV) progression, and whether presence of cardiometabolic risk factors is associated with cfPWV.

STUDY DESIGN

Electronic databases (PubMed, Google Scholar) were searched from inception to May 2018, for all studies which reported cfPWV in children (<19 years of age). Random effects meta-regression quantified the association between time (years) and cfPWV, and a systematic review was performed to determine whether cardiometabolic risk factors are associated with cfPWV.

RESULTS

Data from 28 articles were eligible for inclusion, including 9 reference value (n = 13 100), 5 cardiovascular risk (n = 5257), 10 metabolic risk (n = 2999), and 8 obesity-focused (n = 8760) studies. Meta-regression findings (9 studies) showed that the increase in cfPWV per year (age) was 0.12 m/second (95% CI, 0.07-0.16 m/second) per year, and when stratified by sex the CIs overlapped. Systematic review findings showed that cardiometabolic risk factors were positively associated with cfPWV, including positive associations with blood pressure, impaired glucose metabolism, and metabolic syndrome. However, obesity was not consistently associated with cfPWV.

CONCLUSIONS

Arterial stiffness in children progresses with age and is associated with cardiometabolic risk factors. Although further longitudinal studies are warranted, the presented reference data will be valuable to epidemiologists tracking children, and to scientists and clinicians prescribing therapies to mitigate risk in a population that is increasingly more vulnerable to cardiovascular disease.

MUSCLE MITOCHONDRIAL CAPACITY AND ENDURANCE IN ADULTS WITH TYPE 1 DIABETES

The impact of type 1 diabetes (T1D) on muscle endurance and oxidative capacity is currently unknown.

Purpose

Measure muscle endurance and oxidative capacity of adults with T1D compared to controls.

Methods

A cross-sectional study design with a control group was used. Subjects (19-37 years old) with T1D (n=17) and controls (n=17) were assessed with hemoglobin A1c (HbA1c) and casual glucose. Muscle endurance was measured with an accelerometer at stimulation frequencies of 2, 4, and 6 Hz for a total of nine minutes. Mitochondrial capacity was measured using near-infrared spectroscopy after exercise as the rate constant of the rate of recovery of oxygen consumption.

Results

T1D and control groups were similar in age, sex, height, and race. The T1D group had slightly higher BMI values and adipose tissue thickness over the forearm muscles. Casual glucose was 150±70 mg/dL for T1D and 98±16 mg/dL for controls (P=0.006). HbA1c of T1D subjects was 7.1±0.9% and 5.0±0.4% for controls (P<0.01). Endurance indexes at 2, 4, and 6 Hz were 94.5±5.2%, 81.8±8.4%, and 68.6±13.5% for T1D and 94.6±4.1%, 85.9±6.3%, and 68.7±15.4% for controls (p = 0.97, 0.12, 0.99, respectively). There were no differences between groups in mitochondrial capacity (T1D= 1.9±0.5 min^-1 and control=1.8±0.4 min^-1, P=0.29) or reperfusion rate (T1D= 8.8±2.8s and control=10.3±3.0s, P=0.88). There were no significant correlations between HbA1c and either muscle endurance, mitochondrial capacity or reperfusion rate.

Conclusions

Adults with T1D did not have reduced oxidative capacity, muscle endurance or muscle reperfusion rates compared to controls. HbA1c also did not correlate with muscle endurance, mitochondrial capacity or reperfusion rates. Future studies should extend these measurements to older people or people with poorly-controlled T1D.

Serum osteoprotegerin is an independent marker of central arterial stiffness as assessed using carotid-femoral pulse wave velocity in hemodialysis patients: a cross sectional study

Background

Cardiovascular morbidity and mortality are highly prevalent in patients with end-stage renal disease, and osteoprotegerin (OPG) may be an important link between bone loss and vascular calcification. This study was conducted to evaluate the relationship between central arterial stiffness and serum OPG levels in hemodialysis (HD) patients.

Methods

Blood samples were collected from 120 HD patients, and the carotid–femoral pulse wave velocity (cfPWV) value was measured using a validated tonometry system. The cfPWV value of > 10 m/s was used to define the high artery stiffness group. Serum OPG levels were analyzed categorically into tertiles.

Results

Of the 120 HD patients, 53 (44.2%) were defined as the high arterial stiffness group, who had higher values of systolic blood pressure (p = 0.038), serum calcium (p = 0.007), and OPG (p <  0.001) levels and a higher prevalence of diabetes mellitus (DM, p = 0.001). Increasing tertiles of serum OPG levels were significantly associated with greater height (p = 0.011), male gender (p = 0.008), higher cfPWV values (p = 0.020), and lower intact parathyroid hormone (iPTH, p = 0.049) levels. Multivariable linear regression analysis showed that cfPWV value was independently associated with DM (β = 1.83, p = 0.008) and increasing tertiles of serum OPG levels (β = 0.89 and 1.63 for tertile 2 and tertile 3, respectively, p for trend = 0.035) in HD patients. Multivariable logistic regression analysis revealed that, in addition to age, DM, low iPTH levels, and high serum calcium levels, increasing tertiles of serum OPG levels (OR = 5.34 for tertile 2; OR = 7.06 for tertile 3; p for trend = 0.002) were an independent predictor of high arterial stiffness in HD patients. Serum calcium levels positively correlated with cfPWV value only in the highest OPG tertile group (r = 0.408, p = 0.009).

Conclusion

A positive association was detected between serum OPG levels and central arterial stiffness in HD patients, and patients with high serum OPG levels may have greater influence of calcium load on central arterial stiffening.

Treatment of Diabetes in Older Adults: An Endocrine Society* Clinical Practice Guideline

OBJECTIVE

The objective is to formulate clinical practice guidelines for the treatment of diabetes in older adults.

CONCLUSIONS

Diabetes, particularly type 2, is becoming more prevalent in the general population, especially in individuals over the age of 65 years. The underlying pathophysiology of the disease in these patients is exacerbated by the direct effects of aging on metabolic regulation. Similarly, aging effects interact with diabetes to accelerate the progression of many common diabetes complications. Each section in this guideline covers all aspects of the etiology and available evidence, primarily from controlled trials, on therapeutic options and outcomes in this population. The goal is to give guidance to practicing health care providers that will benefit patients with diabetes (both type 1 and type 2), paying particular attention to avoiding unnecessary and/or harmful adverse effects.

A cross-section study of main determinants of arterial stiffness in Hefei area, China

BACKGROUND

Arterial stiffness has emerged as an independent risk factor for adverse cardiovascular disease events and is the consequence of multiple risk factors. The aim of the present study is to explore the main determinants of arterial stiffness in a Chinese population and to study how the arterial stiffness levels affected by different number of risk factors.

METHODS

This study included 358 subjects in Hefei area of China. Anthropometric indexes, biochemical indexes, cardiovascular function indexes and lifestyle were achieved. Brachial-ankle pulse wave velocity (baPWV) was used to assess arterial stiffness. Multivariate linear regression model was performed to identify the main determinants of arterial stiffness levels.

RESULTS

baPWV was correlated with age, sex, hypertension, various blood pressure components (systolic blood pressure [SPB], diastolic blood pressure, pulse pressure, and central arterial pressure), serum lipids, fasting blood-glucose and body mass index, subendocardial viability ratio (SEVR) and ejection duration (ED) in bivariate correlation analysis. Moreover, baPWV was only positively correlated with age, hypertension and SBP and inversely correlated with SEVR and ED in multivariable regression model. These five variables explained about 74.8% variances of baPWV and age was the strongest determinant of arterial stiffness. In addition, the levels of arterial stiffness increased with the augmented number of risk factors when the total number of factors was no more than 4.

CONCLUSIONS

The main determinants of arterial stiffness were age, hypertension, SBP, SEVR and ED. Furthermore, the number of risk factors had an independent influence on arterial stiffness, it is of great importance to consider the number of risk factors when it comes to cardiovascular risk assessment.

Should we calculate arterial stiffness gradient in middle-aged women with increased cardiovascular risk?

PURPOSE

The study was designed to evaluate clinical and laboratory determinants pulse wave velocity (PWV) ratio in women at the age of 50-65 years without overt cardiovascular disease but having elevated cardiovascular risk, such as hypertension, obesity, diabetes and hypercholesterolemia.

MATERIALS AND METHODS

We analyzed data from 1170 women enrolled in the national-wide primary prevention program. Univariate and multivariate linear regression analysis was used to establish independent risk factors in groups based on clinical data, laboratory values, and comorbidities. Arterial stiffness was evaluated using applanation tonometry technique (SphygmoCor). The PWV ratio was calculated by dividing cfPWV to crPWV.

RESULTS

In multivariate logistic regression analysis, age (OR = 1.109, p < .001), waist circumference (OR = 1.021, p = .001) and mean arterial pressure (OR = 1.031, p < .001) were found as independent clinical determinants of PWV ratio, while independent laboratory determinants were urine albumin to creatinine ratio (OR = 1.189, p = .010), triglycerides (OR = 1.161, p = .034), glucose (OR = 1.28, p = .001) and eGFR (OR = 0.998, p = .007). Diabetes (OR = 1.811, p = .029), hypertension (OR = 2.784, p = .042) and menopause (OR = 1.054, p = .018) were established as independent factors in comorbidities group. The analysis confirmed that PWV ratio (R² = 0.0667, p < .001), as well as carotid radial (R² = 0.0341, p < .001) and carotid femoral PWV (R² = 0.1752, p < .001) is affected by mean arterial blood pressure.

CONCLUSIONS

Age, abdominal obesity, blood pressure, triglycerides, glucose, kidney function parameters and menopause all are associated with PWV ratio. More importance to women with high cardiovascular risk should be given whilst screening and stratifying further progression of the disease.

Aortic-to-brachial artery stiffness gradient is not blood pressure independent

Aortic stiffness predicts cardiovascular mortality but is limited as a risk marker because it is dependent on blood pressure (BP). A potential solution is provided from the ratio of aortic-to-brachial artery stiffness (ab-ratio), which has been shown to be a BP-independent risk marker among patients with renal dysfunction (RD). We sought to determine the BP independence of the ab-ratio in patients with disease, including RD, and healthy populations. The ab-ratio (aortic/brachial pulse wave velocity) and mean arterial pressure (MAP) were recorded in patients with RD (n = 119, aged 65 ± 7 years), hypertension (n = 140, aged 62 ± 9 years), type 2 diabetes mellitus (n = 77, aged 60 ± 9 years) and healthy subjects (n = 99, aged 51 ± 8 years). Multiple-regression analysis was performed to test the independent association of MAP with the ab-ratio adjusted for age, sex, body mass index, glucose and heart rate. There was no significant relationship between the ab-ratio and MAP in patients with RD (β = 0.08, p = 0.34), hypertension (β = 0.04, p = 0.62) or diabetes (β = 0.22, p = 0.11). However, among healthy subjects the ab-ratio was significantly and independently associated with MAP (β = 0.31, p = 0.003). There was a significant difference in the strength of association between the ab-ratio and MAP between patients with disease and healthy subjects (z > 2.2, p < 0.05 all). Although ab-ratio is purported to be a risk marker that is independent of BP, this was observed only among patient populations, and not among healthy subjects. As a result, the ab-ratio has limited potential as a screening tool for the clinical assessment of arterial stiffness in otherwise healthy individuals.

Effect of 12-month intervention with low-dose atorvastatin on pulse wave velocity in subjects with type 2 diabetes and dyslipidaemia

Cardiovascular disease is the leading cause of morbidity and mortality in subjects with type 2 diabetes mellitus. Increased aortic stiffness, assessed with the carotid-femoral pulse wave velocity, is an independent risk factor for cardiovascular disease. Statins reduce effectively cardiovascular disease and mortality in high-risk patients. The aim of this prospective non-randomized, observational study was to examine the impact of treatment with either 10 mg atorvastatin plus diet or diet alone on carotid-femoral pulse wave velocity in subjects with type 2 diabetes mellitus and dyslipidaemia. A total of 79 subjects with type 2 diabetes mellitus and dyslipidaemia were included; 46 subjects were treated with atorvastatin 10 mg daily plus diet and 33 were managed by diet alone for 12 months. Carotid-femoral pulse wave velocity and carotid-radial pulse wave velocity were measured using applanation tonometry. In the atorvastatin-treated group, carotid-femoral pulse wave velocity reduced significantly during the study and there was a trend for reduction in the carotid-radial pulse wave velocity. Total cholesterol, low-density lipoprotein cholesterol, triglycerides and C-reactive protein were reduced only in the atorvastatin-treated participants. No significant changes were found in body mass index, blood pressure, heart rate, diabetes control and high-density lipoprotein cholesterol in either study group. Treatment with low-dose atorvastatin for 12 months improves carotid-femoral pulse wave velocity in subjects with type 2 diabetes mellitus and dyslipidaemia.

Determinants of Vascular Age: An Epidemiological Perspective

BACKGROUND

Vascular age is an emerging health indicator and predictor of end-organ damage to the heart, brain, and kidney. Although there have been many review publications concerning risk factors for vascular aging, most include cross-sectional epidemiological studies, limiting inferences about temporality. There is a need for a review of longitudinal epidemiological studies with repeated measures of vascular structure and function to allow for a systematic examination of determinants of vascular age and the association of vascular aging with outcomes.

CONTENT

Arterial stiffness is the most frequently used measure of vascular aging. We report here results of an extensive literature review of longitudinal cohort studies with repeated measures of arterial stiffness to characterize determinants of vascular age. Additionally, we summarize population-based studies that have focused on the association of arterial stiffness with end-organ damage and adverse cardiovascular outcomes.

SUMMARY

Changes in arterial stiffness are evident in early childhood. In adults, arterial stiffness has been observed to progress at the average rate of 0.2 to 0.7 m/s for every 5 years of life. The state of the science is limited by the small number of studies with repeated measures of arterial stiffness and determinants of arterial stiffness progression, as well as limited studies in children and diverse race/ethnic groups. Several extant studies suggest that beyond age, cardiometabolic risk factors and adverse lifestyle behaviors contribute to arterial stiffening. Therefore, arterial stiffness is important in the assessment of healthy vascular aging and a possible target for the prevention of subclinical and clinical disease.

Associations between Type 2 Diabetes Mellitus and Arterial Stiffness: A Prospective Analysis Based on the Maine-Syracuse Study

BACKGROUND

The aim of this study was to investigate prospective associations between type 2 diabetes mellitus status and the gold standard non-invasive method for ascertaining arterial stiffness, carotid femoral pulse wave velocity.

METHODS

The prospective analysis employed 508 community-dwelling participants (mean age 61 years, 60% women) from the Maine-Syracuse Longitudinal Study. Pulse wave velocity at wave 7 (2006-2010) was compared between those with type 2 diabetes mellitus at wave 6 (2001-2006) (n = 52) and non-diabetics at wave 6 (n = 456), with adjustment for demographic factors, cardiovascular risk factors and lifestyle- and pulse wave velocity-related factors.

RESULTS

Type 2 diabetes mellitus status was associated with a significantly higher pulse wave velocity (12.5 ± 0.36 vs. 10.4 ± 0.12 m/s). Multivariate adjustment for other cardiovascular risk factors and lifestyle- and pulse wave velocity-related variables did not attenuate the findings. The risk of an elevated pulse wave velocity (≥12 m/s) was over 9 times higher for those with uncontrolled type 2 diabetes mellitus than for those without diabetes (OR 9.14, 95% CI 3.23-25.9, p < 0.001).

CONCLUSIONS

Type 2 diabetes mellitus, particularly if uncontrolled, is significantly associated with risk of arterial stiffness later in life. Effective management of diabetes mellitus is an important element of protection from arterial stiffness.

Aortic-Brachial Pulse Wave Velocity Ratio: A Measure of Arterial Stiffness Gradient Not Affected by Mean Arterial Pressure

Background

Aortic stiffness, measured by carotid-femoral pulse wave velocity (cf-PWV), is used for the prediction of cardiovascular risk. This mini-review describes the nonlinear relationship between cf-PWV and operational blood pressure, presents the proposed methods to adjust for this relationship, and discusses a potential place for aortic-brachial PWV ratio (a measure of arterial stiffness gradient) as a blood pressure-independent measure of vascular aging.

Summary

PWV is inherently dependent on the operational blood pressure. In cross-sectional studies, PWV adjustment for mean arterial pressure (MAP) is preferred, but still remains a nonoptimal approach, as the relationship between PWV and blood pressure is nonlinear and varies considerably among individuals due to heterogeneity in genetic background, vascular tone, and vascular remodeling. Extrapolations from the blood pressure-independent stiffness parameter β (β₀) have led to the creation of stiffness index β, which can be used for local stiffness. A similar approach has been used for cardio-ankle PWV to generate a blood pressure-independent cardio-ankle vascular index (CAVI). It was recently demonstrated that stiffness index β and CAVI remain slightly blood pressure-dependent, and a more appropriate formula has been proposed to make the proper adjustments. On the other hand, the negative impact of aortic stiffness on clinical outcomes is thought to be mediated through attenuation or reversal of the arterial stiffness gradient, which can also be influenced by a reduction in peripheral medium-sized muscular arteries in conditions that predispose to accelerate vascular aging. Arterial stiffness gradient, assessed by aortic-brachial PWV ratio, is emerging to be at least as good as cf-PWV for risk prediction, but has the advantage of not being affected by operating MAP.

Key Messages

The negative impacts of aortic stiffness on clinical outcomes are proposed to be mediated through attenuation or reversal of arterial stiffness gradient. Aortic-brachial PWV ratio, a measure of arterial stiffness gradient, is independent of MAP.

Exercise individualized by TRIMPi method reduces arterial stiffness in early onset type 2 diabetic patients: A randomized controlled trial with aerobic interval training

BACKGROUND

Arterial stiffness (AS) and baroreflex sensitivity (BRS) are subclinical markers of vascular diseases in type 2 diabetes (T2D). We evaluated the effects of aerobic interval training (AIT), with loads prescribed according to individual heart rate and lactate profiling obtained during a baseline treadmill test (TRIMPi method), on AS and BRS in patients with early-onset T2D without cardiovascular complications.

POPULATION STUDY AND METHODS

Twenty-two sedentary overweight T2D patients (aged 57±7years) were randomized to 12-weeks open-label of supervised AIT by TRIMPi (n=8) or unsupervised physical activity as per usual care (SOC) (n=11). Following parameters were evaluated (pre- and post-): anthropometrics; six-minute walking test (6MWT); fasting glucose, insulin, HbA1c; Pulse Wave Velocity (PWV) and Augmentation Index (AIxHR75) using radial approach (SphigmoCor System); BRS using Finapress method.

RESULTS

Both interventions significantly improved distance walked during 6MWT (AIT 52±21m; SOC 39±24m, p<0.001 for both). PWV significantly improved with AIT (p<0.001) whereas did not vary with SOC (p=0.47). Similar trend was observed for AIxHR75. Resulting percent changes from baseline were significantly better for AIT vs SOC, in both PWV (-15.8±2.1 vs +1.50±3.4%, p<0.001) and AIxHR75 (-28.9±3.2% vs +12.7±2.4%, p<0.001). BRS similarly improved in both groups (p<0.001 for both), as well as body weight, HbA1c and blood pressure.

CONCLUSION

In sedentary T2D patients, 12-weeks AIT individualized by TRIMPi method improved AS to a greater extent than usual recommendation on physical activity, whilst exerting comparable effects on exercise capacity, glycemic control and body weight. Further researches are needed to ascertain durability of these effects.

Glycemic markers and relation with arterial stiffness in Caucasian subjects of the MARK study

Background

Effect of prediabetes and normal glucose on arterial stiffness remains controversial. The primary aim of this study was to investigate the relationship of fasting plasma glucose (FPG), postprandial glucose (PG) and glycosylated haemoglobin (HbA1c) with brachial-ankle pulse wave velocity (baPWV) and cardio-ankle vascular index (CAVI) in Caucasian adults. The secondary aim was to analyse this relationship by glycaemic status.

Methods

Cross-sectional study. Setting: Primary care. Participants: 2,233 subjects, 35–74 years. Measures: FPG (mg/dL) and HbA1c (%) of all subjects were measured using standard automated enzymatic methods. PG (mg/dL) was self-measured at home two hours after meals (breakfast, lunch and dinner) for one day using an Accu-chek ^® glucometer. CAVI was measured using a VaSera VS-1500^® device (Fukuda Denshi), and baPWV was calculated using a validated equation.

Results

CAVI and baPWV values were significantly higher in subjects with diabetes mellitus than in glucose normal and prediabetes groups (p<0.001). FPG, PG and HbA1c were positively associated with CAVI and baPWV. The β regression coefficient for: HbA1c was 0.112 (CI 95% 0.068 to 0.155) with CAVI, 0.266 (CI 95% 0.172 to 0.359) with baPWV; for PG was 0.006 (CI 95% 0.004 to 0.009 and for FPG was 0.005 (CI 95% 0.002 to 0.008) with baPWV; and for PG was 0.002 (CI 95% 0.001 to 0.003) and 0.003 (CI 95% 0.002 to 0.004) with CAVI (p<0.01 in all cases). When analysing by hyperglycaemic status, FPG, PG and HbA1c were positively associated with CAVI and baPWV in subjects with type 2 diabetes mellitus.

Conclusion

FPG, PG and HbA1c show a positive association with CAVI and baPWV, in Caucasian adults with intermediate cardiovascular risk factors. When analysing by hyperglycaemic status, the association is only maintained in subjects with type 2 diabetes mellitus.

Trial registration

Clinical Trials.gov Identifier: NCT01428934. Registered 2 September 2011. Retrospectively registered. Last updated September 8, 2016.

Aortic-Brachial Arterial Stiffness Gradient and Cardiovascular Risk in the Community: The Framingham Heart Study

A recent study reported that the aortic-brachial arterial stiffness gradient, defined as carotid-radial/carotid-femoral pulse wave velocity (PWV ratio), predicts all-cause mortality better than carotid-femoral pulse wave velocity (CFPWV) alone in dialysis patients. However, the prognostic significance of PWV ratio for cardiovascular disease (CVD) in the community remains unclear. Accordingly, we assessed the correlates and prognostic value of the PWV ratio in 2114 Framingham Heart Study participants (60±10 years; 56% women) free of overt CVD. Mean PWV ratio decreased from 1.36±0.19 in participants aged <40 years to 0.73±0.21 in those aged ≥80 years. In multivariable linear regression, older age, male sex, higher body mass index, diabetes mellitus, lower high-density lipoprotein cholesterol, higher mean arterial pressure, and higher heart rate were associated with lower PWV ratio (P<0.001 for all). During a median follow-up of 12.6 years, 248 first CVD events occurred. In Cox regression models adjusted for standard CVD risk factors, 1-SD changes in CFPWV (hazard ratio, 1.33; 95% confidence interval, 1.10-1.61) and PWV ratio (hazard ratio, 1.32; 95% confidence interval, 1.09-1.59) were associated with similar CVD risks. Models that included conventional CVD risk factors plus CFPWV or PWV ratio gave the same C statistics (C=0.783). Although PWV ratio has been reported to provide incremental predictive value over CFPWV in dialysis patients, we could not replicate these findings in our community-based sample. Our findings suggest that the prognostic significance of PWV ratio may vary based on baseline CVD risk, and CFPWV should remain the criterion standard for assessing vascular stiffness in the community.

The Coupled Bio-Chemo-Electro-Mechanical Behavior of Glucose Exposed Arterial Elastin

Elastin, the principle protein component of the elastic fiber, is a critical extracellular matrix (ECM) component of the arterial wall providing structural resilience and biological signaling essential in vascular morphogenesis and maintenance of mechanical homeostasis. Pathogenesis of many cardiovascular diseases have been associated with alterations of elastin. As a long-lived ECM protein that is deposited and organized before adulthood, elastic fibers can suffer from cumulative effects of biochemical exposure encountered during aging and/or disease, which greatly compromise their mechanical function. This review article covers findings from recent studies of the mechanical and structural contribution of elastin to vascular function, and the effects of biochemical degradation. Results from diverse experimental methods including tissue-level mechanical characterization, fiber-level nonlinear optical imaging, piezoelectric force microscopy, and nuclear magnetic resonance are reviewed. The intriguing coupled bio-chemo-electro-mechanical behavior of elastin calls for a multi-scale and multi-physical understanding of ECM mechanics and mechanobiology in vascular remodeling.

Inactive Matrix Gla-Protein and Arterial Stiffness in Type 2 Diabetes Mellitus

BACKGROUND

Large artery stiffness is increased in diabetes mellitus and causes an excessive pulsatile load to the heart and to the microvasculature. The identification of pathways related to arterial stiffness may provide novel therapeutic targets to ameliorate arterial stiffness in diabetes. Matrix Gla-Protein (MGP) is an inhibitor of vascular calcification. Activation of MGP is vitamin K dependent. We hypothesized that levels of inactive MGP (dephospho-uncarboxylated MGP; dp-ucMGP) are related to arterial stiffness in type 2 diabetes.

METHODS

We enrolled a multiethnic cohort of 66 participants with type 2 diabetes. Carotid-femoral pulse wave velocity (CF-PWV) was measured with high-fidelity arterial tonometry (Sphygmocor Device). Dp-ucMGP was measured with ELISA (VitaK; The Netherlands).

RESULTS

The majority of the participants were middle-aged (62 ± 12 years), male (91%), and had a history of hypertension (82%). Average hemoglobin A1C was 7.2% (55 mmol/mol). Mean dp-ucMGP was 624 ± 638 pmol/l and mean CF-PWV was 11 ± 4 m/sec. In multivariable analyses, dp-ucMGP was independently related to African American ethnicity (β = -0.24, P = 0.005), warfarin use (β = 0.56, P < 0.001), and estimated glomerular filtration rate (eGFR, β = -0.32, P < 0.001). Dp-ucMGP predicted CF-PWV (β = 0.40, P = 0.011), even after adjustment for age, gender, ethnicity, mean arterial pressure, eGFR, and warfarin use.

CONCLUSIONS

In our cross-sectional analysis, circulating dp-ucMGP was independently associated with CF-PWV in type 2 diabetes. This suggests that deficient vitamin K-dependent activation of MGP may lead to large artery stiffening and could be targeted with vitamin K supplementation in the patients with diabetes.

Aortic–Brachial Pulse Wave Velocity Ratio

Aortic stiffness, a cardiovascular risk factor, depends on the operating mean arterial pressure (MAP). The impact of aortic stiffness on cardiovascular outcomes is proposed to be mediated by the attenuation or the reversal of the arterial stiffness gradient. We hypothesized that arterial stiffness gradient is less influenced by changes in MAP. We aimed to study the relationship between MAP and aortic stiffness, brachial stiffness, and arterial stiffness gradient. In a cross-sectional study of a dialysis cohort (group A, n=304) and a cohort of hypertensive or kidney transplant recipient with an estimated glomerular filtration rate of >45 mL/min/1.73 m 2 (group B, n=114), we assessed aortic and brachial stiffness by measuring carotid–femoral and carotid–radial pulse wave velocities (PWV). We used aortic–brachial PWV ratio as a measure of arterial stiffness gradient. Although there was a positive relationship between MAP and carotid–femoral PWV ( R 2 =0.10 and 0.08; P <0.001 and P =0.003) and MAP and carotid–radial PWV ( R 2 =0.22 and 0.12; P <0.001 and P <0.001), there was no statistically or clinically significant relationship between MAP and aortic–brachial PWV ratio ( R 2 =0.0002 and 0.0001; P =0.8 and P =0.9) in group A and B, respectively. Dialysis status and increasing age increased the slope of the relationship between MAP and cf-PWV. However, we found no modifying factor (age, sex, dialysis status, diabetes mellitus, cardiovascular disease, and class of antihypertensive drugs) that could affect the lack of relationship between MAP and aortic–brachial PWV ratio. In conclusion, these results suggest that aortic–brachial PWV ratio could be considered as a blood pressure–independent measure of vascular aging.

A fiber-progressive-engagement model to evaluate the composition, microstructure, and nonlinear pseudoelastic behavior of porcine arteries and decellularized derivatives

The theoretical fiber-progressive-engagement model was proposed to describe the pseudoelastic behavior of an artery pre- and post-decellularization treatments. Native porcine arteries were harvested and decellularized with 0.05% trypsin for 12 h. The uniaxial tensile test data were fitted to the fiber-progressive-engagement model proposed herein. The effects of decellularization on the morphology, structural characteristics, and composition of vessel walls were studied. The experimental stress-strain curve was fitted to the model in the longitudinal and circumferential direction, which demonstrated the adequacy of the proposed model (R²>0.99). The initial and turning strains were similar in the longitudinal and circumferential directions in the aorta, suggesting the occurrence of collagen conjugation in both directions. Discrepancies in the initial and turning strain and initial and stiff modulus in both directions in the coronary artery revealed the anisotropic features of this vessel. Decellularization induced a decrease in the initial and turning strains, a slight change in the initial modulus, and a substantial decrease in the stiffness modulus. The decrease in the initial and turning strain can be attributed to the loss of waviness of collagen bundles because of the considerable decrease in elastin and glycosaminoglycan contents. This simple non-linear model can be used to determine the fiber modulus and waviness degree of vascular tissue. Based on these results, this mechanical test can be used as a screening tool for the selection of an optimized decellularization protocol for arterial tissues.

STATEMENT OF SIGNIFICANCE

Decellularized vascular graft has potential in clinical application, such as coronary artery bypass surgery, peripheral artery bypass surgery or microsurgery. An ideal decellularization protocol requires balance in cell removal efficiency and extracellular matrix preserving. Both biochemical and biomechanical properties are crucial to the success of scaffold in cell seeding and animal study. A comprehensive understanding of the composition, microstructure, and mechanical behavior of the arterial wall is the key to the development of decellularized vascular grafts. For this purpose, we proposed this "Fiber-Progressive-Engagement" model to evaluate the microstructure, composition and mechanical properties of porcine coronary artery. The model provides a new perspective regarding the non-linear behavior of arterial tissue and its decellularized derivatives. It can be widely applied to different types of tissues, as demonstrated in the aorta and coronary artery. This model has several advantages; it provides an improved fit of non-linear curves (R²>0.99), can be used to elucidate the pseudoelastic properties of porcine vascular tissues using the concept of fiber engagement, and can estimate an elastic modulus with greater accuracy (compared to the graphical estimation or calculation by simple linear fittings), as well as to plot typical stress-strain curves.

Arterial Stiffness: Determinants and Relationship to the Metabolic Syndrome

This study aimed to investigate independent determinants of arterial stiffness and evaluate the association of arterial stiffness with the presence of metabolic syndrome (MS). Demographic characteristics, hemodynamic parameters, and cardiovascular (CV) risk factors were assessed in Greek food industry employees with no history of diabetes or CV disease in order to isolate multiple correlates of arterial stiffness as assessed by pulse wave velocity (PWV). Subsequently, logistic regression analysis was performed using as end point the presence of MS, defined according to the National Cholesterol Education Program. Data from 424 participants (mean age 45.3 ∓15.5 years, 298 [70.3%] males, average PWV 8.5 ∓3.6 m/s) were analyzed. PWV was higher in men (8.8 ∓3.1 m/s) compared to women (7.7 ∓2.9 m/s, p<0.01). Age, systolic blood pressure, and heart rate were isolated as multivariate determinants of PWV (adjusted R2 0.511 [p<0.0001] in men and 0.538 [p<0.0001] in women). The overall prevalence of the MS was 14.6%, being similar in both genders. Four variables were shown to be independent predictors of the presence of MS: waist circumference >102 cm (men)/88 cm (women) (OR 8.6, [95% CI 2.8, 20.6], p<0.001), insulin resistance (homeostasis model assessment >4) (6.3, [2.1, 17.6], p<0.001), total cholesterol >240 mg/dL (5.5, [1.7, 12.4], p<0.01), PWV >9 m/s (4.1, [1.5, 9.9], p<0.01). High PWV, which was found to be mostly determined by advanced age, elevated systolic BP, and accelerated heart rate, appeared to exhibit a strong independent association with the presence of MS together with adiposity and insulin resistance. This index should be considered as a useful marker for CV risk stratification.

Skin Autofluorescence and Pentosidine Are Associated With Aortic Stiffening: The Maastricht Study

Arterial stiffening, as characterized by an increase in carotid-femoral pulse-wave velocity or pulse pressure, increases the risk of cardiovascular disease, especially among individuals with type 2 diabetes mellitus. Advanced glycation end products are hypothesized to play a role in the development of arterial stiffness. Therefore, we investigated the association between skin autofluorescence, an estimate of tissue advanced glycation end products, and plasma advanced glycation end products on the one hand and arterial stiffening on the other in 862 participants of The Maastricht Study (mean age of 60 years; 45% women) with normal glucose metabolism (n=469), impaired glucose metabolism (n=140), or type 2 diabetes (n=253). Associations were analyzed with linear regression analysis and adjusted for potential confounders. We found that higher skin autofluorescence as measured by the AGE Reader and plasma pentosidine were independently associated with higher carotid-femoral pulse-wave velocity (sβ 0.10; 95% confidence interval, 0.03-0.17 and 0.10; 0.04-0.16, respectively) and central pulse pressure (sβ 0.08; 95% confidence interval 0.01-0.15 and 0.07; 0.01-0.13, respectively). The associations between skin autofluorescence and pentosidine, and carotid-femoral pulse-wave velocity were more pronounced in individuals with type 2 diabetes mellitus (P-interaction<0.10). These results support the hypothesis that accumulation of advanced glycation end products is involved in arterial stiffening and may explain part of the increased risk of cardiovascular disease in individuals with type 2 diabetes mellitus.

Triglycerides are a predictive factor for arterial stiffness: a community-based 4.8-year prospective study

BACKGROUND

Epidemiological studies have disclosed an independent effect of triglycerides on coronary heart disease despite achievement of low-density lipoprotein cholesterol goals with statin therapy. Arterial stiffness has been increasingly recognized as a strong predictor of cardiovascular disease and atherosclerotic disease. The association between triglycerides and arterial stiffness is not well characterized. We aimed to determine the relationship between triglycerides and arterial stiffness in a community-based longitudinal sample from Beijing, China.

METHODS

We related levels of plasma TGs to measures of arterial stiffness (carotid-femoral pulse wave velocity [PWV] and carotid-radial PWV) in 1447 subjects (mean age, 61.3 years) from a community-based population in Beijing, China.

RESULTS

After a median follow-up interval of 4.8 years, multiple linear regression analysis revealed that TGs were independently associated with carotid-femoral PWV (β = 0.747, P < 0.001) and carotid-radial PWV (β = 0.367, P = 0.001). In the group older than 65 years, the association between baseline TG levels and follow-up carotid-femoral PWV (β = 1.094, P = 0.001) and carotid-radial PWV (β = 0.524, P = 0.002) were strengthened. In forward stepwise multivariate logistic regression analysis, every SD increase in TGδ was associated with a 1.296-increased likelihood of the presence of carotid-femoral PWVδII (OR [per SD increase in TGδ]: 1.296; 95% CI: 1.064 ~ 1.580; P = 0.010) in Model 2, whereas the relationship between TGδ and carotid-radial PWVδII disappeared. In addition, the relationship was strengthened between TGδ and the presence of carotid-femoral PWVδII (OR 1.526, 95% CI: 1.088-2.141, P = 0.014) in the group older than 65 years but not carotid-radial PWVδII. No association was noted in subjects younger than 65 years.

CONCLUSIONS

Lower triglyceride levels were significantly associated with decreases in carotid-femoral PWV, indicating that achieving low TG levels may be an additional therapeutic consideration in subjects with atherosclerotic disease.

Growing-Related Changes in Arterial Properties of Healthy Children, Adolescents, and Young Adults Nonexposed to Cardiovascular Risk Factors: Analysis of Gender-Related Differences

The aims of our work were to determine normal aging rates for structural and functional arterial parameters in healthy children, adolescents, and young adults and to identify gender-related differences in these aging rates. Methods. 161 subjects (mean: 15 years (range: 4–28 years), 69 females) were studied. Subjects included had no congenital or chronic diseases, nor had they been previously exposed to traditional cardiovascular risk factors. Arterial parameters assessed were (1) central blood pressure (BP) and aortic pulse wave analysis, (2) arterial local (pressure-strain elastic modulus) and regional (pulse wave velocity, PWV) stiffness, and (3) arterial diameters and carotid intima-media thickness (CIMT). Simple linear regression models (age as the independent variable) were obtained for all the parameters and the resulting rates of change were compared between genders. Results. No gender-related differences were found in mean values of arterial structural and functional parameters in prepubertal ages (4–8 years), but they started to appear at ~15 years. Boys showed a greater rate of change for central systolic BP, central pulse pressure, CIMT, and carotid-femoral PWV. Conclusion. Gender-related differences in arterial characteristics of adults can be explained on the basis of different growing-related patterns between boys and girls, with no existing differences in prepubertal ages.