Arterial stiffness: a new cardiovascular risk factor?

Relationship between aortic stiffness and the left ventricular function in patients with prediabetes

OBJECTIVE

Several studies have shown that arterial stiffness and ventricular dysfunction are increased in individuals with type 2 diabetes. Aortic stiffness (AS) reflects the mechanical tension and elasticity of the aorta, and increased aortic stiffness is a risk factor for cardiovascular disease. The aim of this study was to evaluate the degree of aortic stiffness and its relationship with the left ventricular (LV) function in patients with prediabetes and healthy control subjects.

METHODS

The study groups were composed of 50 patients with prediabetes and 47 healthy adults with similar demographic characteristics. The LV systolic and diastolic functions were assessed using standard two dimensional (2D) echocardiography, M-mode echocardiography, pulsed-wave (PW) echocardiography and tissue Doppler echocardiography. The degree of aortic strain and distensibility were calculated based on the aortic diameters measured on M-mode echocardiography at a level 3 cm above the aortic valve and the blood pressure values obtained on sphygmomanometry.

RESULTS

There were significant differences between the prediabetic and control groups in the degree of aortic strain (4.7 ± 2.8% vs. 14.9 ± 4.5%; respectively, p<0.001) and distensibility (2.0 ± 1.5 vs. 6.8 ± 2.3; 10(-3) cm(2) dyn(-1), respectively, p<0.001). In addition, significant differences were observed between the patient and control groups in the parameters of the LV systolic and diastolic functions. The left atrial diameter was significantly larger in the prediabetics than in the controls (35.9 ± 3.9 vs. 33.7 ± 4.2; respectively, p=0.027).

CONCLUSION

AS is increased in patients with prediabetes. In addition, there is a significant relationship between the degree of aortic stiffness and the LV function in this patient population. Therefore, the aortic elasticity parameters calculated on 2D echocardiography are useful for predicting early cardiovascular risks in prediabetics.

Calculating cardiac risk in obese adolescents before and after onset of lifestyle intervention

Prevalence and severity of obesity in adolescents is increasing worldwide. The obesity-associated cardiovascular risk factors (CRF) determine cardiac risk as demonstrated by longitudinal studies. Fat distribution and not overall fat mass determines the cardiac risk, since intra-abdominal adipose tissue is especially related to CRFs. Besides classical CRFs such as hypertension, dyslipidemia and impaired glucose metabolism, a proinflammatory and prothrombotic state in obesity is associated with cardiac risk. Adipocytokines such as adiponectin are related to cardiac risk and may present useful predictors of cardiac mortalities in future. Measurement of the carotid intima-media thickness is a new promising noninvasive marker for early cardiovascular changes including atherosclerosis. The therapy of choice to prevent cardiac events in obesity is lifestyle intervention of obese adolescents. However, in clinical practice, the weight loss in lifestyle interventions is only moderate and drug treatment of CRFs is seldom performed.

Impact of diabetes mellitus on arterial stiffness in a representative sample of an urban Brazilian population

BACKGROUND

Independent of other cardiovascular (CV) risk factors, increased arterial stiffness has been established as a predictor of morbidity and mortality. The main aim of this study was to investigate the impact of diabetes on arterial stiffness in a representative sample of an urban Brazilian population plus Amerindians.

METHODS

A total of 1,415 individuals from the general population were randomly selected plus 588 Amerindians from a native community in Brazil. In addition, a sub-sample of 380 individuals from the general population had 5-year follow-up data. Pulse wave velocity (PWV) was measured with a non-invasive automatic device (Complior, Colson; Garges les Gonesses, France) and increased arterial stiffness was defined as PWV ≥ 12 m/s.

RESULTS

In the overall group, diabetic individuals had higher frequencies of increased arterial stiffness and hypertension. They also had higher values of PWV, body mass index, total cholesterol, triglycerides, systolic and diastolic blood pressures compared to non-diabetic individuals (p < 0.01). In an analysis stratified by hypertension, PWV values and increased arterial stiffness frequency were higher in diabetic individuals in both groups (hypertensive and non-hypertensive) (p < 0.05). Furthermore, higher risk for increased arterial stiffness was observed in the diabetic individuals from the overall group (OR = 2.27; CI = 1.47-3.52, p < 0.001) and from the hypertensive group (OR = 2.70; CI = 1.58-4.75, p < 0.001), adjusted for covariates. Regarding the ethnic stratification, diabetic individuals from Amerindian, White, and Mulatto (mixed-race) groups had higher PWV values and a greater frequency of increased arterial stiffness compared to non-diabetic individuals. Both diabetic and non-diabetic individuals had higher PWV values after 5 years. There was no significant difference in the 5-year PWV progression in diabetic compared to non-diabetic individuals.

CONCLUSIONS

These results confirm, in a sample of Brazilian population, that the presence of diabetes is associated with increased arterial stiffness and it may contribute in part to increased cardiovascular risk in diabetic patients.

The influence of gender on carotid artery compliance and distensibility in children and adults

PURPOSE

Given the role of arterial wall elasticity in the development of cardiovascular disease, carotid artery compliance and distensibility have been used commonly over the last decade as predictors of cardiovascular risk, although their gender differences remain unknown. The purpose of our study was to evaluate the impact of gender on carotid arterial elasticity in a large sample of children and adults.

METHODS

Carotid artery compliance and distensibility were measured with ultrasonography in 294 children (157 boys, 137 girls; ages 6-18 years) and 604 adults (291 men, 311 women; ages 18-49 years) previously recruited for a study investigating cardiovascular risk factors. An independent sample t test was used to compare demographic and carotid artery elasticity values by age and gender.

RESULTS

No significant gender difference in carotid arterial compliance and distensibility was observed in children. Women had significantly greater cross-sectional compliance than men (0.004 ± 0.000 versus 0.003 ± 0.000 1/mmHg, p = 0.041).

CONCLUSIONS

We found significant gender difference in carotid compliance in adults, but not in children, suggesting that gender differences in arterial stiffness are not present early in life but emerge later in adulthood.

Developmental programming of cardiovascular disease by prenatal hypoxia

It is now recognized that the quality of the fetal environment during early development is important in programming cardiovascular health and disease in later life. Fetal hypoxia is one of the most common consequences of complicated pregnancies worldwide. However, in contrast to the extensive research effort on pregnancy affected by maternal nutrition or maternal stress, the contribution of pregnancy affected by fetal chronic hypoxia to developmental programming is only recently becoming delineated and established. This review discusses the increasing body of evidence supporting the programming of cardiac susceptibility to ischaemia and reperfusion (I/R) injury, of endothelial dysfunction in peripheral resistance circulations, and of indices of the metabolic syndrome in adult offspring of hypoxic pregnancy. An additional focus of the review is the identification of plausible mechanisms and the implementation of maternal and early life interventions to protect against adverse programming.

Role of exercise in the prevention of cardiovascular disease: results, mechanisms, and new perspectives

On an empirical basis, exercise has been regarded as a fundamental pre-requisite for human well-being and physical integrity since classical times. Only in the last decades, however, scientific evidence has accumulated proving its role in the prevention and treatment of multiple chronic diseases beyond any reasonable doubt. Few treatment strategies in medicine have been tested so rigorously in large cohorts of patients as regular physical exercise. With the advent of molecular biology, the underlying mechanisms, such as NO bioavailability and mobilization of progenitor cells, could be identified. This enhances our understanding of this therapeutic tool. Unfortunately, the low compliance rate of the patients is the major drawback of the intervention exercise training (ET). The objective of this manuscript is to summarize the current knowledge with respect to ET on cardiovascular disease (CVD) and the molecular changes elicited by ET. Finally, we will critically assess reasons why ET as therapeutic option is not as effective at the population level in preventing CVD and what we may change in the future to make ET the most effective intervention to fight the development of CVD.

Impaired aortic elastic properties in patients with adult-onset hypogonadism

BACKGROUND

Recent studies have shown a strong relationship between testosterone levels and vasomotor actions. The aim of this study is to compare the elastic properties of the aorta in male patients with hypogonadism and eugonadal healthy control subjects.

METHOD

A total of 22 male with hypogonadism (mean age: 35.2 ± 9.5 years, mean disease duration: 5.3 ± 1.8 years) and 25 age-, sex- and weight-matched eugonadal healthy subjects (mean age: 34.5 ± 8.2 years) were enrolled in the study. Aortic stiffness (β) index, aortic strain (AoS) and aortic distensibility (AoD) were calculated from the aortic diameters measured by transthoracic echocardiography and blood pressure obtained by sphygmomanometer.

RESULTS

The routinely performed echocardiographic parameters were similar between patient and control groups. There were significant differences between the control and patient groups in β index (1.75 ± 0.44 vs 2.68 ± 1.72, p < 0.001), AoS (18.52 ± 6.44 vs 12.35 ± 3.88%, p < 0.001) and AoD (7.56 ± 2.86 vs 3.96 ± 1.24, 10(-6) cm(2)/dyn, p < 0.001). There were statistically significant positive correlations between the serum total testosterone level and AoD (r = 0.539, p < 0.001) and AoS (r = 0.372, p = 0.036); moreover, there was a negative correlation between the serum total testosterone level and β index (r = - 0.462, p = 0.001). In multivariate analysis, serum total testosterone level was significantly related with AoD, AoS and β index (respectively, RR = 2.88, p = 0.004; RR = 3.45, p = 0.001; RR = 2.64, p = 0.01).

CONCLUSION

The study results showed that aortic elasticity was impaired in patients with hypogonadism. We also have demonstrated a statistically significant correlation between aortic elastic properties and the serum total testosterone level.

Endothelial dysfunction, arterial stiffening, and intima-media thickening in large arteries from HIV-1 transgenic mice

HIV patients on highly active antiretroviral therapy (HAART) exhibit elevated incidence of cardiovascular disease (CVD), including a higher risk of myocardial infarction and prevalence of atherosclerotic lesions, as well as increases in markers of subclinical atherosclerosis including increased carotid artery intima-media thickness (c-IMT), increased arterial stiffness, and impaired flow-mediated dilation. Both HAART and HIV-infection are independent risk factors for atherosclerosis and myocardial infarction. Studies implicate the HIV proteins tat, gp120, vpu, and nef in early on-set atherosclerosis. The objective of this study was to quantify the role of expression of HIV-1 proteins on the vascular function, biomechanics, and geometry of common carotid arteries and aortas. This study employed NL4-3Δ gag/pol transgenic mice (HIV-Tg), which contain the genetic sequence for the HIV-1 proteins env, tat, nef, rev, vif, vpr, and vpu but lacks the gag and pol genes and reports that HIV-Tg mice have impaired aortic endothelial function, increased c-IMT, and increased arterial stiffness. Further, HIV-Tg arteries show decreased elastin content, increased cathepsin K and cathepsin S activity, and increased mechanical residual stress. Thus, mice that express HIV proteins exhibit pre-clinical markers of atherosclerosis and these markers correlate with changes in markers of vascular remodeling. These findings are consistent with the hypothesis that HIV-proteins, independent of HAART treatment or HIV infection, could play a role in of the development of CVD.

Arterial Stiffness

Stiffness of large arteries has been long recognized as a significant determinant of pulse pressure. However, it is only in recent decades, with the accumulation of longitudinal data from large and varied epidemiological studies of morbidity and mortality associated with cardiovascular disease, that it has emerged as an independent predictor of cardiovascular risk. This has generated substantial interest in investigations related to intrinsic causative and associated factors responsible for the alteration of mechanical properties of the arterial wall, with the aim to uncover specific pathways that could be interrogated to prevent or reverse arterial stiffening. Much has been written on the haemodynamic relevance of arterial stiffness in terms of the quantification of pulsatile relationships of blood pressure and flow in conduit arteries. Indeed, much of this early work regarded blood vessels as passive elastic conduits, with the endothelial layer considered as an inactive lining of the lumen and as an interface to flowing blood. However, recent advances in molecular biology and increased technological sophistication for the detection of low concentrations of biochemical compounds have elucidated the highly important regulatory role of the endothelial cell affecting vascular function. These techniques have enabled research into the interaction of the underlying passive mechanical properties of the arterial wall with the active cellular and molecular processes that regulate the local environment of the load-bearing components. This review addresses these emerging concepts.

Differences of aortic stiffness and aortic intima-media thickness according to the type of initial presentation in patients with ischemic stroke

BACKGROUND

Aortic stiffness and intima-media thickness (IMT) are known to be associated with ischemic stroke. The aim of the present study was to investigate the differences of aortic stiffness and IMT between cerebral infarction (CI) and transient ischemic attack (TIA).

METHODS

A total of 500 patients with acute stroke were divided into 2 groups: the TIA group (n = 230, 62.4 ± 12 years, 144 males) versus CI group (n = 270, 63.4 ± 11 years, 181 males). Aortic stiffness index and IMT, as well as conventional cardiovascular risk factors, were compared.

RESULTS

The prevalence of hypertension, diabetes, and dyslipidemia were significantly higher, and left atrial volume and E/E' were significantly elevated in the CI group than in the TIA group. Carotid IMT was significantly thicker in the CI group than in the TIA group. Aortic stiffness index β was significantly higher (7.99 ± 2.70 vs. 7.02 ± 4.30, p = 0.043) and aortic IMT was significantly thicker (1.53 ± 0.41 vs. 1.45 ± 0.39 mm, p = 0.040) in the CI group than in the TIA group. Aortic stiffness index β was significantly correlated with the IMT of the aorta (r = 0.279, p = 0.014), right (r = 412, p < 0.001) and left carotid artery (r = 441, p < 0.001).

CONCLUSION

Aortic stiffness index β and IMT were significantly higher in patients with CI than TIA. The result of the present study suggested that CI is associated with more advanced degree of atherosclerotic and arteriosclerotic process than TIA.

Higher cardiorespiratory fitness attenuates arterial stiffening associated with the Ala54Thr polymorphism in FABP2

Fatty acid binding protein 2 (FABP2) Ala54Thr polymorphism is a candidate gene associated with the risk of cardiovascular disease. Habitual exercise brings higher cardiorespiratory fitness and results in the improvement of cardiovascular disease risk. However, the effect of cardiorespiratory fitness level and FABP2 Ala54Thr polymorphism on the risk of cardiovascular diseases remains unclear. In the present study, a cross-sectional investigation of 837 Japanese men and women was performed to clarify the effects of cardiorespiratory fitness on the relationship between risk of cardiovascular disease and FABP2 Ala54Thr gene polymorphism. The study subjects were divided into high-cardiorespiratory fitness (High-Fit) and low-cardiorespiratory fitness (Low-Fit) groups based on the median value of peak oxygen uptake in each sex and decade. The FABP2 Ala54Thr polymorphism did not significantly affect carotid β-stiffness or blood pressure. In the Low-Fit group, carotid β-stiffness, systolic blood pressure, and diastolic blood pressure were higher for individuals with the Ala/Ala genotype compared with those with the Ala/Thr or Thr/Thr genotype, whereas no differences were observed in the High-Fit group. Additionally, serum triglyceride and plasma glucose levels were lower and serum high-density lipoprotein cholesterol levels were higher in the High-Fit group compared with the Low-Fit group; the FABP2 Ala54Thr polymorphism did not significantly affect these parameters. These results suggest that the higher cardiorespiratory fitness may attenuate the changes in central arterial stiffness and blood pressure that are associated with the FABP2 genotype.

Anthracycline causes impaired vascular endothelial function and aortic stiffness in long term survivors of childhood cancer

Vascular and endothelial functions were investigated in long term survivors of childhood cancer exposed to anthracycline treatment. We enrolled 96 long-term survivors (57 males and 39 females, mean age 14.9 ± 5.3 year) of different childhood cancers and 72 age-, sex-, bodyweight- and blood pressure matched controls (39 males and 33 females, mean age 13.7 ± 4.9 year). Aortic stiffness was characterized by echocardiography. Brachial artery endothelial function was assessed by flow-mediated dilatation (FMD%) and nitrate-mediated dilatation (NTG%). Results were compared between three subgroups: anthracycline treated, only chemotherapy treated and control subgroups. The cumulative anthracycline dose was less than 350 mg/m². The healthy control subgroup had a significantly greater FMD response (13.13 ± 2.40 %), and lower stiffness index (2.08 ± 0.6) than both the anthracycline (7.12 ± 6.28 % and 6.45 ± 3.25, respectively) and only chemotherapy treated (10.17 ± 4.23 % and 4.12 ± 2.32, respectively) subgroups. In the anthracycline treated subgroup a significantly (p < 0.01) lower FMD% response, and higher stiffness index were detected than in the only chemotherapy treated subgroup. Higher triglyceride level, higher cumulative anthracycline dose and lower age at the start of treatment were found to be associated independently with impairment of FMD% response and aortic stiffness. We found a significant negative correlation between FMD and aortic stiffness (p < 0.001) and a positive correlation between FMD and distensibility (p < 0.0001). Childhood cancer long term survivors exposed to anthracycline treatment exhibit a marked preclinical vasculopathy, characterized by endothelial dysfunction and increased arterial stiffness, contributing to a deteriorated cardiovascular function.

Comparison of bilateral pulse arrival time before and after induced vasodilation by axillary block

The propagation time of arterial pulse waves provides information about arterial stiffness. Pulse arrival time (PAT) is calculated as the time between the R-wave (ECG) and three reference points on photoplethysmographic (PPG) pulse waves: foot, first derivative and peak. Because large variation in PAT-values between patients exists, measurements of the contra-lateral arm as reference could be a solution. However, anatomical differences between arteries of the arms could introduce an offset of PAT. Furthermore, when arterial stiffness decreases (e.g. after axillary blockade (AxB)) and pulse wave amplitude increases (vasodilation), the pulse waveform can change. The aim of this study was to investigate whether there is a difference between the PAT of both arms and to evaluate the effect of vasodilation after AxB on PAT. ECG and PPG was measured on both hands in 34 patients, starting 2 min before the injection of local anaesthetic of an AxB and continuing for a period of 30 min after block placement. PAT of the baseline and after AxB were calculated and compared. The mean-PAT of both arms were not significantly different for the three reference points. After AxB, PAT significantly increased for all reference points. PAT can be used for intra-subject comparison.

Blood flow restricted exercise and vascular function

It is established that regular aerobic training improves vascular function, for example, endothelium-dependent vasodilatation and arterial stiffness or compliance and thereby constitutes a preventative measure against cardiovascular disease. In contrast, high-intensity resistance training impairs vascular function, while the influence of moderate-intensity resistance training on vascular function is still controversial. However, aerobic training is insufficient to inhibit loss in muscular strength with advancing age; thus, resistance training is recommended to prevent sarcopenia. Recently, several lines of study have provided compelling data showing that exercise and training with blood flow restriction (BFR) leads to muscle hypertrophy and strength increase. As such, BFR training might be a novel means of overcoming the contradiction between aerobic and high-intensity resistance training. Although it is not enough evidence to obtain consensus about impact of BFR training on vascular function, available evidences suggested that BFR training did not change coagulation factors and arterial compliance though with inconsistence results in endothelial function. This paper is a review of the literature on the impact of BFR exercise and training on vascular function, such as endothelial function, arterial compliance, or other potential factors in comparison with those of aerobic and resistance training.

The Vicorder device compared with SphygmoCor in the assessment of carotid-femoral pulse wave velocity in patients with peripheral arterial disease

To assess the reliability and reproducibility of the Vicorder's carotid-femoral pulse wave velocity (cfPWV) measurements in patients with peripheral arterial disease (PAD) and to compare between cfPWV measurements obtained using the Vicorder with those obtained using the SphygmoCor device as a reference. Some 30 patients with PAD (23 men, mean age 64.9±7.5) underwent cfPWV measurement twice by a single investigator during one visit using the Vicorder and the SphygmoCor according to the manufacturer's instructions. Intra-rater reproducibility for each device was assessed using intraclass correlation coefficients (ICC) and Bland-Altman method. The latter was also used to compare between the two devices. The mean difference (s.d.) between repeated measurements was 0.03±0.92 m s(-1), P=0.85 and 0.01±0.54 m s(-1), P=0.91 for the SphygmoCor and Vicorder, respectively. Measurements of cfPWV were highly reproducible using both devices (ICC=0.94 and 0.92, for the Vicorder and SphygmoCor, respectively). Limits of Agreement using the Bland-Altman method were -1.07 to 1.09 m s(-1) and -1.79 to 1.85 m s(-1) for the Vicorder and the SphygmoCor, respectively. Bland-Altman plots indicated that 90% of the cfPWV measurements using the Vicorder and 93% of the measurements using the SphygmoCor fell within two s.d.s of the mean difference. Transit time (TT) differed significantly between the two devices (mean difference 30±9.2 m s, P<0.001), with the Vicorder recording higher values. Nevertheless, the two devices recorded nearly similar cfPWV measurements (mean difference -0.69±1.6 m s(-1), P=0.02) with 97% of cfPWV values falling within two s.d. values of the mean difference on Bland-Altman plot. Both devices generated highly reproducible cfPWV measurements in patients with PAD and were in good agreement when compared with each other. However, the discrepancy in TT between the two devices lead to the Vicorder producing lower values of cfPWV at high values produced by the SphygmoCor.

Differential impact of heart rate on arterial wall stiffness and thickness in young adults: The Bogalusa Heart Study

Heart rate, a hemodynamic parameter, is an important determinant of arterial wall stiffness. However, information on the relationship of heart rate to arterial wall thickness is inconsistent. This study examined the influence of heart rate on arterial stiffness and thickness in Black and White young adults. The study cohort consisted of 255 Black and 659 White adults age 25 to 43 years enrolled in the Bogalusa Heart Study. Carotid artery intima-media thickness (IMT) was measured by B-mode ultrasound and aorta-femoral pulse wave velocity (af-PWV) by echo-Doppler. There was no difference in heart rate between Blacks and Whites. Males vs. females displayed lower heart rate and higher segmental and composite carotid IMT; Blacks vs. Whites had higher composite carotid IMT (0.83 mm vs. 0.80 mm, P < .01) and af-PWV (5.4 m/s vs. 5.2 m/s, P < .01). In a multivariate regression model adjusting for traditional cardiovascular risk variables, heart rate was independently associated with af-PWV (standardized regression coefficient: beta = .14, P = .01 for Blacks; beta = .06, P = .07 for Whites; beta = .09, P = .003 for total sample), but not with carotid IMT. These results indicate that heart rate plays differential roles in the development of arterial stiffness and subclinical atherosclerosis during young adulthood.

Associations between arterial elasticity and markers of inflammation in healthy older women

The purpose of this investigation was to examine the associations between circulating markers of inflammation and arterial elasticity in healthy older women. Participants were 50 women older than 60 years of age, body mass index 27 ± 4, and physically untrained. Large artery elasticity, small artery elasticity, systemic vascular resistance, total vascular impedance, estimated cardiac output, and estimated cardiac index were determined using pulse contour analysis. Serum concentrations of tumor necrosis factor-α, C-reactive protein (CRP), and interleukin 6 were assessed. Results from Pearson's correlation revealed that tumor necrosis factor-α was inversely associated with large artery elasticity (-.426, p < .01) and estimated cardiac index (-.324, p < .05) and positively associated with systemic vascular resistance (.386, p < .01) and total vascular impedance (.416, p < .01). Additionally, C-reactive protein was inversely associated with large artery elasticity (-.308, p < .01). The overall implication was that tumor necrosis factor-α and C-reactive protein appear to be critical inflammatory cytokines associated with reductions in arterial elasticity in older women.

Constitutive modeling of mouse carotid arteries using experimentally measured microstructural parameters

Changes in the local mechanical environment and tissue mechanical properties affect the biological activity of cells and play a key role in a variety of diseases, such as cancer, arthritis, nephropathy, and cardiovascular disease. Constitutive relations have long been used to predict the local mechanical environment within biological tissues and to investigate the relationship between biological responses and mechanical stimuli. Recent constitutive relations for soft tissues consider both material and structural properties by incorporating parameters that describe microstructural organization, such as fiber distributions, fiber angles, fiber crimping, and constituent volume fractions. The recently developed technique of imaging the microstructure of a single artery as it undergoes multiple deformations provides quantitative structural data that can reduce the number of estimated parameters by using parameters that are truly experimentally intractable. Here, we employed nonlinear multiphoton microscopy to quantify collagen fiber organization in mouse carotid arteries and incorporated measured fiber distribution data into structurally motivated constitutive relations. Microscopy results demonstrate that collagen fibers deform in an affine manner over physiologically relevant deformations. The incorporation of measured fiber angle distributions into constitutive relations improves the model's predictive accuracy and does not significantly reduce the goodness of fit. The use of measured structural parameters rather than estimated structural parameters promises to improve the predictive capabilities of the local mechanical environment, and to extend the utility of intravital imaging methods for estimating the mechanical behavior of tissues using in situ structural information.

Is obstructive sleep apnoea causally related to arterial stiffness? A critical review of the experimental evidence

Large elastic arteries and smaller muscular conduit arteries become stiffer with ageing, a process that is accelerated in the presence of cardiovascular disease (CVD). In recent years, numerous techniques have been developed to measure arterial stiffness, either in single vessels or in entire muscular arterial trees. These techniques have increasingly been shown to improve stratification of cardiovascular risk and risk reduction beyond that provided by conventional risk factors. Obstructive sleep apnoea (OSA) has been increasingly linked with excess cardiovascular morbidity and mortality however the mechanisms are still not well understood. Robustly designed studies have shown that treatment of OSA with nasal continuous positive airway pressure improves important intermediate risk factors for CVD including hypertension and endothelial function. More recently, there has been increased exploration of arterial stiffness in both cross-sectional and interventional studies in OSA patients. This review aims to give the reader a better understanding of the measurement and pathophysiology of arterial stiffness as well as providing an indication of how well a prognostic indicator are the various measures of arterial stiffness for hard cardiovascular endpoints. A critical appraisal is then provided of cross-sectional and interventional studies that have explored these same techniques in OSA populations.

Age at onset and vascular pathology in late-life depression

OBJECTIVE

There is considerable evidence to suggest that late-onset depression may be etiologically distinct from early-onset depression. The aim of this study was to compare vascular function and magnetic resonance imaging-defined brain ischemic changes between early-onset depressed (EOD) and late-onset depressed (LOD) subjects.

DESIGN

Case-control study.

PARTICIPANTS

Twenty-five subjects with late-life depression recruited from secondary care were divided into groups with EOD (<60 years, 11 subjects) and LOD (>60 years, 14 subjects).

MEASURES

All subjects underwent a variety of vascular assessments including pulse wave analysis, pulse wave velocity, carotid intima media thickness (IMT), and magnetic resonance imaging of the brain to assess white matter hyperintensities.

RESULTS

The mean age of LOD subjects was 71.3 ± 4.0 years and EOD was 73.6 ± 4.7 years (p = NS). There were no baseline differences in vascular risk or sociodemographic variables. LOD subjects had significantly higher common carotid IMT (EOD: 0.06 [0.01]; LOD: 0.09 [0.02], p = 0.02), carotid plaques (EOD: 2.1 [1.1]; LOD: 5.4 [3.9], p = 0.02), and peripheral augmentation index (EOD: 81.7 [7.9]; LOD: 96.2 [21.6], p = 0.04) when compared with early-onset subjects, indicating more vascular pathology. There were no group differences in white matter hyperintensities. Age at onset of depression was positively correlated with peripheral augmentation index, common carotid IMT, and plaque index.

CONCLUSION

This study suggests that elderly subjects with LOD have greater vascular impairment than those with an early-onset illness. Whether preventing vascular disease at an earlier age may decrease the risk of last onset depression is a potential area for future research.

C-reactive protein is associated with aortic stiffness in a cohort of African American and white women transitioning through menopause

OBJECTIVE

Arterial stiffness is a marker of cardiovascular health. Arterial stiffness and C-reactive protein (CRP) are linked to cardiovascular outcomes. Increases in both inflammation and arterial stiffness are known to occur with menopause. The association between CRP and arterial stiffness is well accepted; however, no study has determined whether there are differences in this association by menopause status and race, independent of age.

METHODS

The cross-sectional association between CRP and aortic pulse wave velocity (PWV), a validated measure of central arterial stiffening, was evaluated in 307 African American and white women enrolled in an ancillary study to the Study of Women's Health Across the Nation. Women were categorized into premenopausal or early perimenopausal (n = 185) and late perimenopausal or postmenopausal (n = 122).

RESULTS

Natural log-transformed CRP was not associated with PWV in a linear regression model adjusted for age and cardiovascular risk factors (β = 15.9, P = 0.11). Moreover, models stratified by menopause status showed a linear relationship between CRP and PWV among late perimenopausal or postmenopausal women (β = 36.2, P = 0.049) but not for premenopausal or early perimenopausal women (β = 5.9, P = 0.61). The menopause status × log-transformed CRP and menopause status × race interactions were significant in their respective models adjusted for age and risk factors (P = 0.03 for both); however, when combined into one model, the two interactions were slightly attenuated (P = 0.063 and 0.052, respectively).

CONCLUSIONS

Menopause is strengthening the association between CRP and PWV, independent of age, and this effect seems to be stronger among African American women. This study provides a potential mechanism for the increased risk of cardiovascular disease among postmenopausal women.

Cyclooxygenase inhibition augments central blood pressure and aortic wave reflection in aging humans

The augmentation index and central blood pressure increase with normal aging. Recently, cyclooxygenase (COX) inhibitors, commonly used for the treatment of pain, have been associated with transient increases in the risk of cardiovascular events. We examined the effects of the COX inhibitor indomethacin (Indo) on central arterial hemodynamics and wave reflection characteristics in young and old healthy adults. High-fidelity radial arterial pressure waveforms were measured noninvasively by applanation tonometry before (control) and after Indo treatment in young (25 ± 5 yr, 7 men and 6 women) and old (64 ± 6 yr, 5 men and 6 women) subjects. Aortic systolic (control: 115 ± 3 mmHg vs. Indo: 125 ± 5 mmHg, P < 0.05) and diastolic (control: 74 ± 2 mmHg vs. Indo: 79 ± 3 mmHg, P < 0.05) pressures were elevated after Indo treatment in older subjects, whereas only diastolic pressure was elevated in young subjects (control: 71 ± 2 mmHg vs. Indo: 76 ± 1 mmHg, P < 0.05). Mean arterial pressure increased in both young and old adults after Indo treatment (P < 0.05). The aortic augmentation index and augmented pressure were elevated after Indo treatment in older subjects (control: 30 ± 5% vs. Indo 36 ± 6% and control 12 ± 1 mmHg vs. Indo: 18 ± 2 mmHg, respectively, P < 0.05), whereas pulse pressure amplification decreased (change: 8 ± 3%, P < 0.05). In addition, older subjects had a 61 ± 11% increase in wasted left ventricular energy after Indo treatment (P < 0.05). In contrast, young subjects showed no significant changes in any of the variables of interest. Taken together, these results demonstrate that COX inhibition with Indo unfavorably increases central wave reflection and augments aortic pressure in old but not young subjects. Our results suggest that aging individuals have a limited ability to compensate for the acute hemodynamic changes caused by systemic COX inhibition.

Association between the C242T polymorphism in the p22phox gene with arterial stiffness in the Brazilian population

NADPH oxidase p22phox subunit is responsible for the production of reactive oxygen species in the vascular tissue. The C242T polymorphism in the p22phox gene has been associated with diverse coronary artery disease phenotypes, but the findings about the protective or harmful effects of the T allele are still controversial. Our main aim was to assess the effect of p22phox C242T genotypes on arterial stiffness, a predictor of late morbidity and mortality, in individuals from the general population. We randomly selected 1,178 individuals from the general population of Vitoria City, Brazil. Genotypes for the C242T polymorphism were detected by PCR-RFLP, and pulse wave velocity (PWV) values were measured with a noninvasive automatic device Complior. p22phox and TNF-α gene expression were quantified by real-time PCR in human arterial mammary smooth muscle cells. In both the entire and nonhypertensive groups: individuals carrying the TT genotype had higher PWV values and higher risk for increased arterial stiffness [odds ratio (OR) 1.93, 95% confidence interval (CI) 1.27-2.92 and OR 1.78, 95% CI 1.07-2.95, respectively] compared with individuals carrying CC+CT genotypes, even after adjustment for covariates. No difference in the p22phox gene expression according C242T genotypes was observed. However, TNF-α gene expression was higher in cells from individual carrying the T allele, suggesting that this genetic marker is associated with functional phenotypes at the gene expression level. In conclusion, we suggest that p22phox C242T polymorphism is associated with arterial stiffness evaluated by PWV in the general population. This genetic association shed light on the understanding of the genetic modulation on vascular dysfunction mediated by NADPH oxidase.

Tai Chi, arterial compliance, and muscle strength in older adults

BACKGROUND

Aerobic exercise can alleviate the declines in arterial compliance common in older adults. However, when combined with strength training, aerobic exercise may not reduce arterial compliance. Tai Chi practice has been found to improve muscle strength and cardiopulmonary function in older subjects, but whether or not it improves arterial compliance is not known. The primary aim of this study was to investigate whether Tai Chi practitioners have better arterial compliance and muscle strength.

DESIGN

Twenty-nine older Tai Chi practitioners (73.7 ± 4.5 years) and 36 healthy control subjects (71.4 ± 6.6 years) participated in this cross-sectional study.

METHODS

The participants were independent in their daily living activities. They were screened for apparent cardiovascular disease and underwent arterial compliance testing and isokinetic knee muscle strength testing at 30°/s.

RESULTS

Tai Chi practitioners showed significantly better haemodynamic parameters than the controls as indexed by larger and small artery compliance. They also demonstrated greater eccentric muscle strength in both knee extensors and flexors.

CONCLUSION

The findings of better muscle strength without jeopardizing arterial compliance suggests that Tai Chi could be a suitable exercise for older persons to improve both cardiovascular function and muscle strength.

The effect of tumor necrosis factor-α antagonists on arterial stiffness in rheumatoid arthritis: a literature review

BACKGROUND

There is evidence that patients with rheumatoid arthritis (RA) have a higher arterial stiffness than their age-matched healthy counterparts and thus have a higher cardiovascular risk. Under National Institute for Clinical Excellence guidelines, tumor necrosis factor-α (TNF-α) antagonists are indicated clinically in patients with severe active rheumatoid disease. TNF-α antagonists have been found to reduce inflammatory markers in RA; however, it is debatable if they have favorable effects on the cardiovascular system. This review evaluates the effect of TNF-α antagonists on arterial stiffness, a predictor of cardiovascular disease, in RA patients.

SEARCH STRATEGY

A search of Ovid MEDLINE and ISI Web of Knowledge databases was conducted to identify studies into the effect of TNF-α antagonists on arterial stiffness in RA patients. Eight studies matching the search criteria were included for analysis.

FINDINGS

Two methods were used to assess arterial stiffness: pulse wave velocity and augmentation index. Despite inconsistencies in augmentation index values, aortic pulse wave velocity in all but one study was significantly reduced following TNF-α antagonist treatment. Most studies had methodological limitations, including inadequate sample size, nonblinding of those involved in the measurements, and inadequate inclusion/exclusion criteria. Variation in results could be due to the use of different TNF-α antagonists, different outcome measures being used, and differences in follow-up.

CONCLUSIONS

The balance of evidence suggests that TNF-α antagonists may have a beneficial effect on arterial stiffness and therefore cardiovascular risk. However, larger more robust longer term studies are warranted to confirm recent findings.

Arterial stiffness identification of the human carotid artery using the stress-strain relationship in vivo

Arterial stiffness is well accepted as a reliable indicator of arterial disease. Increase in carotid arterial stiffness has been associated with carotid arterial disease, e.g., atherosclerotic plaque, thrombosis, stenosis, etc. Several methods for carotid arterial stiffness assessment have been proposed. In this study, in vivo noninvasive assessment using applanation tonometry and an ultrasound-based motion estimation technique was applied in seven healthy volunteers (age 28±3.6years old) to determine pressure and wall displacement in the left common carotid artery (CCA), respectively. The carotid pressure was obtained using a calibration method by assuming that the mean and diastolic blood pressures remained constant throughout the arterial tree. The regional carotid arterial wall displacement was estimated using a 1D cross-correlation technique on the ultrasound radio frequency (RF) signals acquired at a frame rate of 505-1010Hz. Young's moduli were estimated under two different assumptions: (i) a linear elastic two-parallel spring model and (ii) a two-dimensional, nonlinear, hyperelastic model. The circumferential stress (σ(θ)) and strain (ɛ(θ)) relationship was then established in humans in vivo. A slope change in the circumferential stress-strain curve was observed and defined as the transition point. The Young's moduli of the elastic lamellae (E(1)), elastin-collagen fibers (E(2)) and collagen fibers (E(3)) and the incremental Young's moduli before ( [Formula: see text] ) and after the transition point ( [Formula: see text] ) were determined from the first and second approach, respectively, to describe the contribution of the complex mechanical interaction of the different arterial wall constituents. The average moduli E(1), E(2) and E(3) from seven healthy volunteers were found to be equal to 0.15±0.04, 0.89±0.27 and 0.75±0.29MPa, respectively. The average moduli [Formula: see text] and [Formula: see text] of the intact wall (both the tunica adventitia and tunica media layers) were found to be equal to 0.16±0.04MPa and 0.90±0.25MPa, respectively. The average moduli [Formula: see text] and [Formula: see text] of the tunica adventitia were found to be equal to 0.18±0.05MPa and 0.84±0.22MPa, respectively. The average moduli [Formula: see text] and [Formula: see text] of the tunica media were found to be equal to 0.19±0.05MPa and 0.90±0.25MPa, respectively. The stiffness of the carotid artery increased with strain during the systolic phase. In conclusion, the feasibility of measuring the regional stress-strain relationship and stiffness of the normal human carotid artery was demonstrated noninvasively in vivo.

Obese children have higher arterial elasticity without a difference in endothelial function: the role of body composition

The childhood obesity epidemic is expected to increase cardiovascular disease risk, but the impact of obesity on vascular function in children is not fully understood. The purpose of this study was to determine the effect of obesity and maturation on vascular function in normal weight (BMI: 25-75 percentile) and obese (BMI: ≥95 percentile) children ages 8-18 years old. Large and small artery elasticity (LAEI and SAEI, respectively), measured by diastolic radial pulsewave contour analysis, and reactive hyperemia index (RHI), measured by peripheral arterial tonometry, were obtained, along with anthropometric and biochemical outcomes, in 61 normal weight and 62 obese children. SAEI and LAEI increased with age and were 30% and 18% higher, respectively, in obese children (P < 0.01). In contrast, reactive hyperemia increased with age in the normal weight group but did not differ between groups. Multivariate modeling was used to select variables that explained differences in vascular outcomes. The best model for LAEI in normal weight children was height alone (r(2) = 0.49), whereas for obese children the best model included height + fat mass (r(2) = 0.40). For SAEI, there were no significant models for normal weight children, but for obese children the best model included lean mass + fat mass (r(2) = 0.36). Obese children had greater lean and fat mass, and more advanced Tanner stages than their normal weight peers. The increased elasticity observed in obese children appears to reflect accelerated growth and maturation without affecting vascular reactivity measured by reactive hyperemia. Longitudinal follow up will be essential in determining effects on future vascular disease risk.

Estimation of arterial baroreflex sensitivity in relation to carotid artery stiffness

Arterial baroreflex has a significant role in regulating blood pressure. It is known that increased stiffness of the carotid sinus affects mecanotransduction of baroreceptors and therefore limits baroreceptors capability to detect changes in blood pressure. By using high resolution ultrasound video signal and continuous measurement of electrocardiogram (ECG) and blood pressure, it is possible to define elastic properties of artery simultaneously with baroreflex sensitivity parameters. In this paper dataset which consist 38 subjects, 11 diabetics and 27 healthy controls was analyzed. Use of diabetic and healthy test subjects gives wide scale of arteries with different elasticity properties, which provide opportunity to validate baroreflex and artery stiffness estimation methods.

Angiotensin converting enzyme inhibitors effect on arterial stiffness and wave reflections: a meta-analysis and meta-regression of randomised controlled trials

OBJECTIVE

Several studies have assessed the effect of angiotensin converting enzyme inhibitors (ACEIs) on arterial stiffness and wave reflections as measured by pulse wave velocity (PWV) and augmentation index (AIx), respectively. We conducted a meta-analysis to investigate this effect in comparison to placebo and to other antihypertensive agents. Additionally, we investigated this effect when ACEIs are combined with other antihypertensive agents and in comparison to a combination of antihypertensive agents.

METHODS

MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials (CENTRAL) were searched from inception to May 2011 on randomised controlled trials (RCTs) which assessed the effect of ACEIs on arterial stiffness vs. placebo or no treatment and ACEIs vs. angiotensin receptor blockers (ARBs), calcium channel blockers (CCBs), β-blockers and diuretics. RCTs which assessed the effect of ACEIs combined with other antihypertensives or compared ACEIs with a combination of antihypertensives were also sought. Data from included RCTs were pooled with use of fixed and random effects meta-analysis of the weighted mean change differences between the comparator groups. Heterogeneity across studies was assessed with the I(2) statistic.

RESULTS

In 5 trials including 469 patients, treatment with ACEIs (n=227) vs. placebo (n=216) significantly reduced PWV (pooled mean change difference -1.69, 95% C.I. -2.05, -1.33, p<0.00001 with insignificant heterogeneity). In 9 trials which included 378 patients, treatment with ACEIs (n=178) insignificantly reduced PWV when compared with other antihypertensives (ARBs, CCBs, β-blockers, diuretics and a combination of ACEI and ARB) (n=220) (pooled mean change difference -0.19, 95% C.I. -0.59, 0.21, p=0.36, I(2)=0%). ACEI effect on AIx in comparison to placebo was assessed in 7 trials. Treatment with ACEIs significantly reduced AIx (pooled mean change difference -3.79, 95% C.I. -5.96, -1.63, p=0.0006) with significant heterogeneity. In 7 trials, treatment with ACEIs significantly reduced AIx when compared with other antihypertensives (pooled mean change difference -1.84, 95% C.I. -3, -0.68, p=0.002, I(2)=32%, p for heterogeneity=0.11). However, this effect was only significant when compared with β-blockers (pooled mean change difference -1.6, 95% C.I. -2.84, -0.36, p=0.01). Mean BP differences between baseline and end of treatment did not predict the treatment (ACEI) induced changes in PWV.

CONCLUSIONS

ACEIs reduce PWV and AIx which are markers of arterial stiffness and wave reflections in patients with different pathological conditions. However, due to the lack of high quality and properly powered RCTs, it is not clear whether ACEIs are superior to other antihypertensive agents in their effect on arterial stiffness. The ability of ACEIs to reduce arterial stiffness (PWV) seems to be independent of its ability to reduce BP.

Association of N-terminal pro brain natriuretic peptide and impaired aortic elastic property in hypertensive patients

BACKGROUND

N-terminal pro brain natriuretic peptide (NT-proBNP) is closely related to risk stratification in many cardiovascular diseases. The objective of this study was to evaluate the association of NT-proBNP and impaired aortic elastic property in hypertensive patients.

METHODS

One hundred fifty-five hypertensive patients without obvious cardiac dysfunction were included and divided in tertiles based on their NT-proBNP concentration. Eighty-six normotensive healthy volunteers were also enrolled as controls. All subjects underwent Doppler echocardiography to assess cardiac parameters and aortic distensibility index. Plasma NT-proBNP was measured by electrochemiluminescence.

RESULTS

The parameters of aortic elastic property were decreased and NT-proBNP was significantly increased in hypertensive patients compared with controls (all P<0.05). Among hypertensive patients, higher NT-proBNP tertiles were associated with larger systolic and diastolic aortic diameters, longer deceleration time of the E wave velocity (DT) and isovolumic relaxation time; decreased E/A ratio and more percent of diastolic dysfunction. The parameters of aortic elastic property showed stepwise decreases from the first tertiles to the third tertiles (P<0.05). Multiple linear regression analysis showed that concentrations of NT-proBNP were significantly correlated with age and impaired aortic distensibility.

CONCLUSIONS

NT-proBNP is a marker for impaired aortic elastic property in hypertensive patients. Measurement of NT-proBNP could be indicated in hypertensive patients for further risk stratification.

Carotid arterial wall characteristics are associated with incident ischemic stroke but not coronary heart disease in the Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND AND PURPOSE

Ultrasound measurements of arterial stiffness are associated with atherosclerosis risk factors, but limited data exist on their association with incident cardiovascular events. We evaluated the association of carotid ultrasound-derived arterial stiffness measures with incident coronary heart disease (CHD) and ischemic stroke in the Atherosclerosis Risk in Communities (ARIC) study.

METHODS

Carotid arterial strain and compliance, distensibility and stiffness indices, pressure-strain, and Young elastic moduli were measured in 10 407 individuals using ultrasound. Hazard ratios for incident CHD (myocardial infarction, fatal CHD, coronary revascularization) and stroke in minimally adjusted (age, sex, center, race) and fully adjusted models (minimally adjusted model+diabetes, height, weight, total cholesterol, high-density lipoprotein cholesterol, tobacco use, systolic blood pressure, antihypertensive medication use, and carotid intima-media thickness) were calculated.

RESULTS

The mean age was 55.3 years. Over a mean follow-up of 13.8 years, 1267 incident CHD and 383 ischemic stroke events occurred. After full adjustment for risk factors and carotid intima-media thickness, all arterial stiffness parameters (carotid arterial strain hazard ratio [HR], 1.14 [95% CI, 1.02-1.28]; arterial distensibility HR, 1.19 [1.02-1.39]; stiffness indices HR, 1.14 [1.04-1.25]; pressure-strain HR, 1.17 [1.06-1.28]; Young elastic moduli HR, 1.13 [1.03-1.24]), except arterial compliance (HR, 1.02 [0.90-1.16], were significantly associated with incident stroke but not with CHD.

CONCLUSIONS

After adjusting for cardiovascular risk factors, ultrasound measures of carotid arterial stiffness are associated with incident ischemic stroke but not incident CHD events despite that the 2 outcomes sharing similar risk factors.

CLINICAL TRIAL REGISTRATION

URL: www.clinicaltrials.gov. Unique identifier: NCT00005131.

Morphological and functional alterations in the aorta of the chronically hypoxic fetal rat

In human pregnancy, reduced placental perfusion has been associated with fetal aortic thickening. However, the relative contributions of fetal undernutrition versus fetal underoxygenation to triggering alterations in fetal cardiovascular development remain uncertain. Here, we isolate the effects of chronic fetal hypoxia on fetal cardiovascular development in a specific rodent model of chronic fetal hypoxia independent of changes in nutrition during pregnancy. Pregnant rats were housed under normoxic (21% O(2)) or hypoxic (13% O(2)) conditions from day 6 to day 20 of gestation. At day 20, pups and placentas were weighed. Fetal thoraces were fixed for quantitative histological analysis of the aorta. In a separate group, fetal aortic reactivity was assessed via in vitro wire myography. The experiments controlled for sex and within-litter variation. Placental weight was increased and fetal weight maintained in hypoxic pregnancy. Hypoxic pregnancy led to a 176% increment in wall thickness and a 170% increment in the wall-to-lumen area ratio of the fetal aorta. Fetal aortic vascular reactivity was markedly impaired, showing reduced constrictor and relaxant responsiveness in hypoxic pregnancy. Chronic developmental hypoxia independent of changes in nutrition has profound effects on the morphology and function of the fetal aorta in a mammalian species.

Aortic stiffness is reduced beyond blood pressure lowering by short-term and long-term antihypertensive treatment: a meta-analysis of individual data in 294 patients

BACKGROUND

Arterial stiffness is an independent predictor of cardiovascular events and mortality in hypertensive patients. The influence of different antihypertensive drug classes on improving arterial stiffness beyond blood pressure reduction is not widely available. We aimed to determine whether the artery stiffness can be improved because of antihypertensive treatments independently of blood pressure lowering.

METHODS

We conducted a meta-analysis of individual data from 15 randomized, controlled, double-blind, parallel group trials performed in our laboratory between 1987 and 1994. The primary endpoint was the changes of carotid-femoral pulse wave velocity (PWV) after treatment in 294 patients with mild-to-moderate essential hypertension untreated. Treatments tested were placebo (n = 88), angiotensin-converting enzyme inhibitors (ACEIs) (n = 75), calcium antagonists (n = 75), beta-blocker (n = 30), and diuretic (n = 26).

RESULTS

In the short-term and long-term trials, PWV decreased significantly by -0.75 and -1.3 m/s in the active treatment group compared with by +0.17 and -0.44 m/s in the placebo group, respectively. Active treatment was independently related to the changes in PWV and explained 5 and 4% of the variance in the short-term and long-term trials, respectively. In the short-term trials, ACEIs were more effective than calcium antagonists and placebo on improving arterial stiffness. In the long-term trials, ACEI, calcium antagonists, beta-blocker, and diuretic reduced significantly PWV compared to placebo.

CONCLUSION

Our study shows that antihypertensive treatments improve the arterial stiffness beyond their effect on blood pressure.

Segmental analysis of carotid arterial strain using speckle-tracking

BACKGROUND

Increased arterial stiffness has been shown to be associated with aging and cardiovascular risk factors. Speckle-tracking algorithms are being used to measure myocardial strain. The aims of this study were to evaluate whether speckle-tracking could be used to measure carotid arterial strain (CAS) reproducibly in healthy volunteers and to determine if CAS was lesser in individuals with diabetes.

METHODS

Bilateral electrocardiographically gated ultrasound scans of the distal common carotid arteries (three cardiac cycles; 14-MHz linear probe; mean frame rate, 78.7 ± 8.9 frames/sec) were performed twice (2-4 days apart) on 10 healthy volunteers to test repeatability. Differences in CAS between healthy subjects (n = 20) and patients with diabetes (n = 21) were examined. Peak CAS was measured in each of six equal segments, and averages of all segments (i.e., the global average), of the three segments nearest the probe, and of the three segments farthest from the probe (i.e., the far wall average) were obtained.

RESULTS

Global CAS (intraclass correlation coefficient = 0.40) and far wall average (intraclass correlation coefficient = 0.63) had the greatest test-retest reliability. Global and far wall averaged CAS values were lower in patients with diabetes (4.29% [SE, 0.27%] and 4.30% [SE, 0.44%], respectively) than in controls (5.48% [SE, 0.29%], P = .001, and 5.58% [SE, 0.44%], P = .003, respectively). This difference persisted after adjustment for age, gender, race, and hemodynamic parameters.

CONCLUSIONS

Speckle-tracking to measure CAS is feasible and modestly reliable. Patients with diabetes had lower CAS obtained with speckle-tracking compared with healthy controls.

Arterial function of carotid and brachial arteries in postmenopausal vegetarians

Background:

Vegetarianism is associated with a lower risk of cardiovascular disease. However, studies of arterial function in vegetarians are limited.

Methods:

This study investigated arterial function in vegetarianism by comparing 49 healthy postmenopausal vegetarians with 41 age-matched omnivores. The arterial function of the common carotid artery was assessed by carotid duplex, while the pulse dynamics method was used to measure brachial artery distensibility (BAD), compliance (BAC), and resistance (BAR). Fasting blood levels of glucose, lipids, lipoprotein (a), high-sensitivity C-reactive protein, homocysteine, and vitamin B12 were also measured.

Results:

Vegetarians had significantly lower serum cholesterol, high-density and low-density lipoprotein, and glucose compared with omnivores. They also had lower vitamin B12 but higher homocysteine levels. Serum levels of lipoprotein (a) and high-sensitivity C-reactive protein were no different between the two groups. There were no significant differences in carotid beta stiffness index, BAC, and BAD between the two groups even after adjustment for associated covariates. However, BAR was significantly lower in vegetarians than in omnivores. Multiple linear regression analysis revealed that age and pulse pressure were two important determinants of carotid beta stiffness index and BAD. Vegetarianism is not associated with better arterial elasticity.

Conclusion:

Apparently healthy postmenopausal vegetarians are not significantly better in terms of carotid beta stiffness index, BAC, and BAD, but have significantly decreased BAR than omnivores. Prevention of vitamin B12 deficiency might be beneficial for cardiovascular health in vegetarians.

Stiffness of the large arteries in individuals with and without Down syndrome

BACKGROUND

Down syndrome is known to cause premature aging in several organ systems. However, it remains unclear whether this aging effect also affects the structure and function of the large arterial trunks. In this controlled study, the possibility of changes in the large arteries due to aging was evaluated in patients with Down syndrome.

METHODS

Eighty-two subjects of both genders were selected. The Down syndrome group had 41 active subjects consisting of 19 males and 22 females (mean age 21 ± 1, range 13-42 years) without cardiovascular complications and who did not use vasoactive drugs. The control group consisted of 41 healthy individuals without trisomy 21 of the same gender and age as the Down syndrome group and who did not use vasoactive medication. Carotid-femoral pulse wave velocity was obtained as an index of aortic stiffness using an automatic noninvasive method.

RESULTS

Individuals with Down syndrome had significantly lower blood pressure than those in the control group. Systolic blood pressure for the Down syndrome group and control group was 106 ± 2 mmHg vs 117 ± 2 mmHg (P < 0.001), respectively; diastolic blood pressure was 66 ± 2 mmHg vs 77 ± 2 mmHg (P < 0.001); and mean arterial pressure was 80 ± 1 mmHg vs 90 ± 1 mmHg (P < 0.001). Only age and systolic blood pressure were shown to correlate significantly with pulse wave velocity, but the slopes of the linear regression curves of these two variables showed no significant difference between the two study groups. Pulse wave velocity, which was initially significantly lower in the Down syndrome group (7.51 ± 0.14 m/s vs 7.84 ± 0.12 m/s; P <0.05), was similar between the groups after systolic blood pressure adjustment (7.62 ± 0.13 m/s vs 7.73 ± 0.13 m/s).

CONCLUSION

Despite evidence in the literature that patients with Down syndrome undergo early aging, this process does not seem to affect the large arterial trunks, given that values of carotid-femoral pulse wave velocity were similar in individuals with or without trisomy 21. Considering that Down syndrome presents with chronic hypotension, it is reasonable to propose that the prolonged reduction of arterial distending pressure may contribute to functional preservation of the arteries in patients with Down syndrome.

Long-term exposure to airborne particles and arterial stiffness: the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Increased arterial stiffness could represent an intermediate subclinical outcome in the mechanistic pathway underlying associations between average long-term pollution exposure and cardiovascular events.

OBJECTIVE

We hypothesized that 20 years of exposure to particulate matter (PM) ≤ 2.5 and 10 μm in aerodynamic diameter (PM2.5 and PM10, respectively) would be positively associated with arterial stiffness in 3,996 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) who were seen at six U.S. study sites.

METHODS

We assigned pollution exposure during two decades preceding a clinical exam (2000-2002) using observed PM10 from monitors nearest participants' residences and PM10 and PM2.5 imputed from a space-time model. We examined three log-transformed arterial stiffness outcome measures: Young's modulus (YM) from carotid artery ultrasound and large (C1) and small (C2) artery vessel compliance from the radial artery pulse wave. All associations are expressed per 10 μg/m3 increment in PM and were adjusted for weather, age, sex, race, glucose, triglycerides, diabetes, waist:hip ratio, seated mean arterial pressure, smoking status, pack-years, cigarettes per day, environmental tobacco smoke, and physical activity. C1 and C2 models were further adjusted for heart rate, weight, and height.

RESULTS

Long-term average particle exposure was not associated with greater arterial stiffness measured by YM, C1, or C2, and the few associations observed were not robust across metrics and adjustment schemes.

CONCLUSIONS

Long-term particle mass exposure did not appear to be associated with greater arterial stiffness in this study sample.

Early Identification of Vascular Damage in Patients With Systemic Sclerosis

Vascular involvement in systemic sclerosis (SSc) plays a key role in the pathogenesis of fibrosis. We assessed arterial stiffness using a new echo-tracking technique in patients with SSc asymptomatic for cardiovascular diseases. We enrolled 22 patients (21 female, 63 ± 14 years) and 20 controls (12 female, 62 ± 3 years). Carotid intima-media thickness (IMT) was comparable between the 2 groups (1.1 ± 0.3 vs 1.0 ± 0.4 mm, P = ns), whereas the stiffness parameters were significantly increased in patients (β: 9.5 ± 4.2 vs 5.8 ± 1.1, P = .001; pulse wave velocity [PWV]: 6.5 ± 1.5 vs 5.2 ± 0.6 m/sec, P = .003). A correlation between stiffness parameters, anti-Scl-70 antibodies (β: r = .46, P = .03; PWV: r = .50, P = .02), and anticentromere antibodies (β: r = -.54, P = .020; PWV: r = -.53, P = .023) was found. Echo-tracking technique may be valuable in early identification of vascular involvement in patients with SSc.

The relationship of gamma-glutamyltransferase to aortic elastic properties in young patients with prehypertension

Some cross-sectional studies have demonstrated a positive association between serum gamma-glutamyltransferase (GGT) levels and blood pressure. Accordingly, we aimed to analyze serum GGT levels in patients with prehypertension and examine the relationship with aortic elasticity parameters. The study population consisted of 25 newly diagnosed prehypertensive individuals and 25 healthy control subjects. Aortic strain, distensibility index, and stiffness index beta were calculated from aortic diameters measured by echocardiography and blood pressures simultaneously measured by sphygmomanometry. Prehypertensive patients were detected to have significantly lower aortic distensibility and strain indexes compared to control subjects aortic distensibility. However, aortic stiffness index beta of the prehypertensive group was significantly higher compared to that of the control group (3.73 ± 1.41 vs. 2.97 ± 0.82, p = 0.02). The mean GGT levels were found to be higher in patients with prehypertension compared to those of controls (47.9 ± 15.9 U/L vs. 36.1 ± 9.4 U/L, p = 0.003). When multiple linear regression analysis was done to clarify the contributions of GGT to aortic elasticity adjusting for age, body mass index, uric acid, serum glucose, heart rate, low-density lipoprotein (LDL)-cholesterol, high-density lipoprotein (HDL)-cholesterol, and triglyceride, we observed that only serum GGT levels were significantly associated with aortic elasticity parameters (for aortic strain beta = -0.247, p < 0.001; for aortic distensibility beta = -0.108, p < 0.001; for stiffness index beta = 0.063, p < 0.001). Whatever the mechanism is, young patients with prehypertension have higher serum GGT levels compared to healthy control subjects. More importantly, increased GGT levels are independently associated with impaired aortic elasticity in patients with prehypertension.