Β-stiffness Index Research Articles

Influence of blood flow velocity on arterial distensibility of carotid artery in healthy men.

Decreased distensibility of carotid artery is independently associated with the incidence of cardiovascular and cerebrovascular events. Arterial distensibility is determined by vascular tone. Since shear stress is an important driving force of vasodilatory substances production form endothelial cells, we hypothesized that local basal (i.e., resting) arterial blood flow velocity is associated with regional arterial distensibility. To test this hypothesis, we determined the influence of local blood flow velocity on carotid arterial distensibility in cross-sectional study design. In a total of 73 apparent healthy men (18-64years), carotid arterial properties, including measures of carotid arterial distensibility and BFV at rest, were evaluated via B-mode and Doppler ultrasound imaging and applanation tonometry system. Carotid arterial peak BFV and the absolute and normalized pulsatile BFV significantly correlated with age (r=-0.453 to -0.600, p<0.0001), whereas mean and minimum BFV were not influenced by age. Distensibility coefficient of carotid artery correlated with peak BFV (r=0.305, p<0.01) and more strongly with pulsatile (i.e., systolic minus end-diastolic) BFV (r=0.406, p<0.0001) and the normalized pulsatile BFV by time-averaged velocity (r=0.591, p<0.0001). Multi-regression analysis revealed that age (β=-0.57, p<0.0001) was the primary independent determinant for distensibility coefficient. In addition with this, carotid lumen diameter (β=-0.202, p<0.01) and the normalized pulsatile BFV (β=0.237, p<0.05) were significant independent determinants of distensibility coefficient. Qualitatively similar results (although inverse in direction) were obtained by use of β-stiffness index. These results suggest that greater gradient of blood flow velocity during a cardiac cycle are favorably associated with distensibility of carotid artery.

Arterial stiffness of lifelong Japanese female pearl divers.

Japanese female pearl divers called Ama specialize in free diving in the cold sea for collecting foods and pearls in oysters. Exercising in the water combined with marked bradycardia and pressor responses provides a circulatory challenge to properly buffer or cushion elevated cardiac pulsations. Because Ama perform repeated free dives throughout their lives, it is possible that they may have adapted similar arterial structure and function to those seen in diving mammals. We compared arterial stiffness of lifelong Japanese pearl divers with age-matched physically inactive adults living in the same fishing villages. A total of 115 Japanese female pearl divers were studied. Additionally, 50 physically inactive adults as well as 33 physically active adults (participating in community fitness programs) living in the same coastal villages were also studied. There were no differences in age (∼65 yr), body mass index, and brachial blood pressure between the groups. Measures of arterial stiffness, cardio-ankle vascular index and β-stiffness index were lower (P < 0.05) in pearl divers and physically active adults than in their physically inactive peers. Augmentation pressure and augmentation index adjusted for the heart rate of 75 beats/min were lower (P < 0.05) in pearl divers than in other groups. These results indicate that lifelong Japanese pearl divers demonstrate reduced arterial stiffness and arterial wave reflection compared with age-matched physically inactive peers living in the same fishing villages.

Association between blood viscosity and common carotid artery elasticity.

Elastic properties of the vessel wall are associated with atherosclerosis and major cardiovascular events. Several physiological and pathological conditions can affect arterial elasticity, but few studies have considered the role of hemorheological parameters. The present study aimed to investigate the relationship between hemorheological parameters and vascular stiffness in the carotid artery district. One hundred and two individuals were enrolled. Blood and plasma viscosity were measured by a cone-plate viscometer (Wells-Brookfield DV-III, Stoughton, U.S.A.). Echo-Doppler evaluation of carotid arteries was performed in order to calculate elastic indexes (strain, β-stiffness index and distensibility). The association between hemorheological parameters and carotid elasticity indexes was assessed by simple and multiple regression analyses. In simple correlation analysis, only blood viscosity was directly associated with β-stiffness index (r = 0.20, p = 0.05) and inversely with strain (r =-0.26, p = 0.01) and distensibility (r =-0.34, p = 0.001). After adjusting for cardiovascular risk factors, blood viscosity, but not plasma viscosity or hematocrit, was independently associated carotid arterial measures, together with age, obesity, hypertension, and dyslipidemia. The results of the present study demonstrate a strong association between blood viscosity and common carotid elasticity indexes.

Effect of weight loss induced by energy restriction on measures of arterial compliance: A systematic review and meta-analysis

AimTo conduct a systematic review and meta-analysis of clinical trials involving adults, to determine the effect of weight loss induced by energy restriction with or without exercise, anti-obesity drugs or bariatric surgery on measures of arterial stiffness and compliance. MethodsA systematic search of Pubmed, EMBASE, MEDLINE and the Cochrane Library was conducted to find intervention trials (randomised/non-randomised) that aimed to achieve weight loss and included the following outcome measures: cardio-ankle vascular index (CAVI), direct measures of area/diameter related to pressure change (including β-stiffness index, brachial or carotid artery compliance, aortic, carotid or brachial artery distensibility and strain), measures derived from peripheral pulse wave analysis (including augmentation index, augmentation pressure, distal oscillatory, proximal capacitive and systemic compliance) and pulse pressure. Data were analysed using Comprehensive Meta Analysis V2 using random effects analysis. Standardised mean difference (SMD) is reported with negative values indicating an improvement. ResultsA total of 43 studies, involving 4231 participants, were included in the meta-analysis. Mean weight loss was approximately 11% of initial body weight. Weight loss improved CAVI (SMD −0.48; p = 0.04), β-stiffness index (SMD = −0.98; p = 0.001), arterial compliance (SMD = −0.61; p = 0.0001) and distensibility (SMD −1.10; p = 0.005), distal oscillatory compliance (SMD = −0.41; p = 0.03), proximal capacitive compliance (SMD −0.66; p = 0.009), systemic arterial compliance (SMD −0.71; p = 0.003) and reflection time (SMD −0.51; p = 0.001). Augmentation index, strain, augmentation pressure and pulse pressure were not significantly changed with weight loss. ConclusionWeight loss induced by energy restriction improves some measures of arterial compliance and stiffness.

Effects of sodium nitrite supplementation on vascular function and related small metabolite signatures in middle-aged and older adults

Insufficient nitric oxide (NO) bioavailability plays an important role in endothelial dysfunction and arterial stiffening with aging. Supplementation with sodium nitrite, a precursor of NO, ameliorates age-related vascular endothelial dysfunction and arterial stiffness in mice, but effects on humans, including the metabolic pathways altered, are unknown. The purpose of this study was to determine the safety, feasibility, and efficacy of oral sodium nitrite supplementation for improving vascular function in middle-aged and older adults and to identify related circulating metabolites. Ten weeks of sodium nitrite (80 or 160 mg/day, capsules, TheraVasc; randomized, placebo control, double blind) increased plasma nitrite acutely (5- to 15-fold, P < 0.001 vs. placebo) and chronically (P < 0.10) and was well tolerated without symptomatic hypotension or clinically relevant elevations in blood methemoglobin. Endothelial function, measured by brachial artery flow-mediated dilation, increased 45-60% vs. baseline (P < 0.10) without changes in body mass or blood lipids. Measures of carotid artery elasticity (ultrasound and applanation tonometry) improved (decreased β-stiffness index, increased cross-sectional compliance, P < 0.05) without changes in brachial or carotid artery blood pressure. Aortic pulse wave velocity was unchanged. Nitrite-induced changes in vascular measures were significantly related to 11 plasma metabolites identified by untargeted analysis. Baseline abundance of multiple metabolites, including glycerophospholipids and fatty acyls, predicted vascular changes with nitrite. This study provides evidence that sodium nitrite supplementation is well tolerated, increases plasma nitrite concentrations, improves endothelial function, and lessens carotid artery stiffening in middle-aged and older adults, perhaps by altering multiple metabolic pathways, thereby warranting a larger clinical trial.

Abstract 18689: Lower Carotid Artery Compliance and Greater Carotid β-stiffness Index are Associated With Slower Processing Speed and Reduced Working Memory Performance in Older Healthy Adults

Introduction: Higher central elastic artery stiffness is associated with greater brain white matter hyperintensity volume and lower cognitive performance in older adults. However, it is unknown if higher central artery stiffness is related to regional decreases in brain white matter integrity (WMI) and reductions in working memory or processing speed. We hypothesized that greater large elastic artery stiffness would be associated with lower working memory and slower processing speed as well as lower regional WMI in older adults. Methods: In young (n=19; 23.8 ± 0.7 yrs) and older (n=22; 64.4 ± 4.2 yrs; range 60-71 yrs) healthy adults, aortic stiffness (carotid-femoral pulse wave velocity, cfPWV, via tonometry) and carotid artery compliance and β-stiffness index (carotid artery ultrasound and tonometry) were determined non-invasively. WMI was assessed by fractional anisotrophy (FA) (3T MRI) from diffusion tensor images. An N-Back task and letter and pattern comparison tests were performed as measures of working memory and processing speed, respectively. d’Prime, a measure of signal detection, was calculated on the N-Back task as a ratio of positive ‘hits’ to ‘false alarm’ responses. Results: cfPWV (8.4 ± 0.5 vs. 5.2 ± 0.2 m/sec, P&lt;0.01) and carotid β-stiffness (11.3 ± 0.9 vs. 6.1 ± 0.7 U, P&lt;0.01) were greater and carotid compliance (0.16 ± 0.02 vs. 0.07 ± 0.01 mm/mmHg, P&lt;0.01) was lower in older vs. young adults. Carotid β, but not aortic, stiffness was associated with slower processing speed on letter (10.7 ± 0.5 vs. 13.5 ± 0.6 units/ 30 sec, p&lt;0.01) and pattern (16.6 ± 0.6 vs. 22.0 ± 0.7 units/30 sec, p&lt;0.01) comparison tasks and reduced working memory (1.8 ± 0.2 vs. 3.1± 0.2, P&lt;0.01) in older vs. young adults. Lower carotid compliance was associated with slower performance on the letter (r=0.55, P&lt;0.01) and pattern (r=0.54, P&lt;0.01) tests and lower d’Prime (r=0.48, P&lt;0.05). Greater β-stiffness was related to pattern comparison scores only (r=-0.54, P&lt;0.01). Aortic stiffness, carotid compliance and β-stiffness were not related to WMI in any brain region. Conclusions: Our results suggest that lower carotid artery compliance and greater β-stiffness are associated with reduced working memory performance and slower processing speed but not regional WMI in older adults.

Segmental Aortic Stiffness in Children and Young Adults With Connective Tissue Disorders: Relationships With Age, Aortic Size, Rate of Dilation, and Surgical Root Replacement.

Aortic diameter is an imperfect predictor of aortic complications in connective tissue disorders (CTDs). Novel indicators of vascular phenotype severity such as aortic stiffness and vertebral tortuosity index have been proposed. We assessed the relation between aortic stiffness by cardiac MRI, surgical root replacement, and rates of aortic root dilation in children and young adults with CTDs. Retrospective analysis of cardiac MRI data on children and young adults with a CTD was performed to derive aortic stiffness measures (strain, distensibility, and β-stiffness index) at the aortic root, ascending aorta, and descending aorta. Vertebral tortuosity index was calculated as previously described. Rate of aortic root dilation before cardiac MRI was calculated as change in echocardiographic aortic root diameter z score per year. In 83 CTD patients (median age, 24 years; range, 1-55; 17% <18 years of age; 60% male), ascending aorta distensibility was reduced in comparison with published normative values: median z score, -1.93 (range, -8.7 to 1.3; P<0.0001 versus normals). Over a median follow-up period of 2.7 years, there were no aortic dissections or deaths, but 16 of 83 (19%) patients underwent surgical aortic root replacement. In multivariable analysis, lower aortic root strain (P=0.05) and higher vertebral tortuosity index (P=0.01) were independently associated with aortic root replacement. Lower ascending aorta strain (P=0.02) was associated with a higher rate of aortic root dilation. Higher aortic stiffness is associated with higher rates of surgical aortic replacement and aortic root dilation in children and young adults with CTDs.

Obesity and arterial stiffness in children: systematic review and meta-analysis.

Childhood obesity is associated with risk factors for cardiovascular disease. Arterial stiffness is considered one of the earliest detectable measures of vascular damage. There is controversy in the literature regarding the effects of childhood obesity on arterial stiffness. The objective of this study is to systematically review the literature and to conduct a meta-analysis comparing measures of central arterial stiffness in children and adolescents with obesity to healthy body mass index controls. Literature searches were conducted using databases (eg, MEDLINE, EMBASE) and citations cross-referenced. Studies assessing central pulse wave velocity or β-stiffness index were included. A random effects meta-analysis of the standardized mean difference and 95% confidence intervals in arterial stiffness between children with obesity and control children was performed for each arterial stiffness measure. A total of 523 studies were identified. Fifteen case-control studies were included, with 2237 children/adolescents (1281 with obesity, 956 healthy body mass index controls) between 5 and 24 years of age. All studies measuring carotid and aortic β-stiffness index and 10/12 studies measuring central pulse wave velocity reported greater arterial stiffness in children/adolescents with obesity compared with controls. A random effects meta-analysis was performed revealing a significant effect of obesity on pulse wave velocity (standardized mean difference=0.718; 95% confidence interval=0.291-1.415), carotid β-stiffness index (0.862; 0.323-1.402), and aortic β stiffness index (1.017; 0.419-1.615). These findings indicate that child/adolescent obesity is associated with greater arterial stiffness. However, further research is needed to address confounders, such as pubertal status, that may affect this relationship in children. In the future, these techniques may be useful in risk stratification and guiding clinical management of obese children to optimize cardiovascular outcomes.

Vascular function, cerebral cortical thickness, and cognitive performance in middle-aged Hispanic and non-Hispanic Caucasian adults.

Hispanics are at increased risk for acquiring cardiovascular risk factors that contribute to cognitive dysfunction. To compare indices of vascular health with measures of cerebral gray matter integrity, 60 middle-aged Hispanic and non-Hispanic Caucasian participants were matched across age, sex, years of education, and mental status. Arterial stiffness was characterized by β-stiffness index and carotid-femoral pulse wave velocity, and magnetic resonance imaging estimated cortical thickness in a priori regions of interest known to be susceptible to vascular risk factors. Measures of arterial stiffness were significantly higher in Hispanics than in non-Hispanic Caucasians. Hispanics exhibited thinner left inferior frontal gyrus (LIFG) cortical thickness (P=.04) with concurrently lower language (P=.02), memory (P=.03), and attention-executive functioning (P=.02). These results suggest that compromised vascular health may occur simultaneously with cortical thinning of the LIFG as an early neuropathological alteration in Hispanics.

Peripheral vascular stiffness, assessed with two-dimensional speckle tracking versus the degree of coronary artery calcification, evaluated by tomographic coronary artery calcification index.

IntroductionEven in asymptomatic patients, the result of atherosclerosis progression is deterioration of the function and morphology of the artery wall. Two-dimensional speckle-tracking (2DST) is a sonographic technique that allows for precise evaluation of arterial wall compliance. Together with measurement of intima-media thickness (IMT), it can be applied for quick and non-invasive assessment of the progression of peripheral artery atherosclerosis.Material and methodsFifty-eight patients of mean age 61 years (SD 10.6) underwent cardiac computed tomography (CT) and subsequent ultrasonographic evaluation of the left common carotid artery. The calcium score was calculated according to the Agatston method and compared with IMT, circumferential strain variables assessed by 2DST, conventional arterial stiffness parameters (β-stiffness index and elastic modulus) and clinical data. Intra-observer and inter-observer agreement was evaluated.ResultsStrain variables and IMT differed significantly in patients with calcium score (CS) > 0 and CS = 0. Moreover, they correlated with CS, systolic blood pressure and age of patients. Conventional stiffness parameters were not able to identify the group of patients with calcifications present in the coronary arteries. For the 2DST technique, interclass and intraclass agreements were 84.83% and 94.42% respectively.ConclusionsCircumferential strain variables assessed by 2DST and measurement of IMT can be used for evaluation of peripheral artery deterioration in patients until the 6th decade of life. These parameters reflect the development of calcifications in coronary arteries and, more importantly, can be used for a more detailed estimation of the atherosclerosis risk in patients with CS = 0.

Carotid artery stiffness and hemodynamic pulsatility during cognitive engagement in healthy adults: a pilot investigation.

The matching of vascular supply to neuronal metabolic demand during cognitive engagement is known as neurovascular coupling (NVC). Arterial stiffness is a prominent determinant of pulsatility in the systemic circulation and may thus indirectly impact NVC. In this pilot investigation, we explored changes in carotid artery stiffness and cerebrovascular hemodynamic pulsatiltiy during cognitive engagement in healthy adults. Twenty-seven adults (age 39 ± 3 years, BMI 24 ± 1 kg/m(2)) underwent Doppler ultrasonography of the common carotid artery (CCA) combined with applanation tonometry to derive (i) CCA elastic modulus (Ep) and β-stiffness index; (ii) CCA flow pulsatility index (PI); (iii) CCA pulse pressure, (iv) CCA augmentation index (AIx). Cerebral PI was assessed using transcranial Doppler at the middle cerebral artery (MCA). All measures were made at rest and during an incongruent Stroop task. CCA PI was reduced (1.75 ± 0.06 to 1.57 ± 0.06, P < 0.05) while MCA PI was unchanged (0.75 ± 0.02 to 0.75 ± 0.02, P > 0.05) during Stroop. Brachial pulse pressure increased during Stroop (43 ± 1 to 46 ± 1 mm Hg, P < 0.05) while CCA pulse pressure was unchanged (36 ± 1 to 35 ± 1 mm Hg, P > 0.05). Similarly, CCA Ep (54.5 ± 5.5 to 53.8 ± 4.9 kPa, P > 0.05) and β-stiffness index (4.4 ± 0.4 to 4.2 ± 0.3 aU, P > 0.05) were unchanged. CCA AIx increased (1 ± 4 to 13 ± 4%, P < 0.05). Carotid pressure pulsatility is unaltered while carotid flow pulsatility is reduced during cognitive engagement. Carotid artery stiffness does not change suggesting that factors other than the dynamic elastic properties of the CCA buffer cerebrovascular hemodynamic pulsatility during cognitive engagement.

Interplay between arterial stiffness and diastolic function: a marker of ventricular-vascular coupling.

We evaluated the interplay between left ventricular diastolic function and large-artery stiffness in asymptomatic patients at increased risk of heart failure and no structural heart disease (Stage A). We divided 127 consecutive patients (mean age 49 ± 17 years) with risk factors for heart failure who were referred to our laboratory to rule out structural heart disease into two groups according to presence (Group 1, n = 35) or absence (Group 2, n = 92) of grade I left ventricular diastolic dysfunction. Doppler imaging with high-resolution echo-tracking software was used to measure intima-media thickness (IMT) and stiffness of carotid arteries. Group 1 had significantly higher mean age, blood pressure, left ventricular mass index, carotid IMT and arterial stiffness than Group 2 (P < 0.05). Overall, carotid stiffness indices (β-stiffness index, augmentation index and elastic modulus) and 'one-point' pulse wave velocity each showed inverse correlation with E-wave velocity, E' velocity and E/A ratio, and direct correlation with A-wave velocity, E-wave deceleration time and E/E' ratio (P < 0.05). Arterial compliance showed negative correlations with the echocardiographic indices of left ventricular diastolic function (P < 0.05). On logistic regression analysis, age, hypertension, SBP, pulse pressure, left ventricular mass index, carotid IMT and stiffness parameters were associated with grade I left ventricular diastolic dysfunction (P < 0.05 for each). However, on multivariate logistic analysis, only 'one-point' pulse wave velocity and age were independent predictors (P = 0.038 and P = 0.016, respectively). An independent association between grade I left ventricular diastolic dysfunction and increased arterial stiffness is demonstrated at the earliest stage of heart failure. Hence, assessment of vascular function, beyond cardiac function, should be included in a comprehensive clinical evaluation of these patients.

Increased Central Arterial Stiffness Explains Baroreflex Dysfunction in Spinal Cord Injury

After cervical spinal cord injury (SCI), orthostatic hypotension and intolerance commonly ensue. The cardiovagal baroreflex plays an important role in the acute regulation of blood pressure (BP) and is associated with the onset of presyncope. The cardiovagal baroreflex is dysfunctional after SCI; however, this may be influenced by either increased stiffening of the arteries containing the stretch-receptors (which has been shown in SCI) or a more downstream neural mechanism (i.e., solitary nucleus, sinoatrial node). Identifying where along this pathway baroreflex dysfunction occurs may highlight a potential therapeutic target. This study examined the relationship between spontaneous cardiovagal baroreflex sensitivity (BRS) and common carotid artery (CCA) stiffness in those with high level SCI before and after midodrine (alpha1-agonist) administration, as well as in able-bodied controls, to evaluate: (1) the role arterial stiffening plays mediating baroreflex function after SCI and (2) the effect of normalizing BP on these parameters. Three to five min recordings of beat-by-beat BP and heart rate, as well as 30 sec duration recordings of CCA diameter were used for analysis. All participants were tested supine and during upright-tilt. Arterial stiffness (β-stiffness index) was elevated in those with SCI when upright (+12%; p<0.05). Further, β-stiffness index was negatively related to reduced BRS in those with SCI when upright (R2=0.55; p<0.05), but not in able-bodied persons. Normalizing BP did not improve BRS or CCA stiffness. This study clearly shows that reduced BRS is closely related to increased arterial stiffness in the population with SCI.

Circulating cf-DNA: A promising, noninvasive tool for assessment of early cardio-metabolic risk

In 1948, Mandel and colleagues were the first group to report the presence of circulating nucleic acids in the human bloodstream [1]. The origin of cell-free DNA (cf-DNA) is not fully understood, but apoptosis, necrotic death, cell lysis and active release are possible mechanisms of cf-DNA release into the blood circulation [2]. Circulating cf-DNA is a recent area of increased research interest, with nearly 9000 related papers in the PubMed library. This research has explored a wide range of topics, including the uses of circulating cf-DNA as a cancer prognostic factor, an indicator for intensive care unit admission, and a diagnostic marker of carcinogenesis, injury, sepsis and autoimmune disease [2e5]. The pathophysiological significance of circulating cf-DNA in cardiovascular disease has not received much attention until recently. However, scattered experimental and clinical studies have shed light upon this interesting issue [6e8]. Ten years ago, a clinical study by Chang et al. showed elevated circulating cf-DNA in patients with myocardial infarction [6]. Recently, an observational cohort study clearly demonstrated that plasma cf-DNA levels are a useful biomarker for predicting the outcome after out-of-hospital

Validity and reliability of aortic pulse wave velocity and augmentation index determined by the new cuff-based SphygmoCor Xcel

Aortic pulse wave velocity (AoPWV) and augmentation index (AIx) are commonly used measures of large elastic artery stiffness and wave reflection, respectively. Recently, a new cuff-based SphygmoCor device (Xcel) has been developed to measure both AoPWV and AIx. We sought to examine the following: (1) the validity of Xcel compared with the well-validated tonometry-based SphygmoCor device (MM3); (2) the intratest and day-to-day reliability of Xcel; (3) the influence of body side (right or left) on Xcel measurements; and (4) the relation of Xcel measurements to carotid artery compliance, distensibility and β-stiffness index. We found that measurements of AoPWV and AIx between Xcel and MM3 were not different (P=0.26 and P=0.43, N=22 and 26, respectively) and were strongly related (r=0.85 and 0.75, P<0.0001), and based on Bland-Altman plots there was good agreement between them. Intra-test (intraclass correlation=0.996 and 0.983, P<0.0001; AoPWV and AIx, N=24 and 26, respectively) and day-to-day reliability (intraclass correlation=0.979 and 0.939, P<0.0001) were high. Xcel AoPWV and AIx on the left versus right body side were not different (P=0.19 and P=0.58, N=14 and 15, respectively) and were highly correlated (r=0.99 and 0.94, P<0.0001). AoPWV and AIx measured with Xcel were positively related with β-stiffness index (r=0.62 and 0.51, P< or = 0.005, N=23 and 24, respectively) and negatively related with distensibility (r = -0.58 and -0.44, P < or = 0.02, N=23 and 24, respectively). In conclusion, Xcel measures of AIx and AoPWV are valid, highly reliable and not affected by body side. Xcel is a useful tool for use in research and the clinic.

Lack of changes in carotid artery compliance with systemic nitric oxide synthase inhibition

Proximal large elastic arteries (ascending aorta and carotid artery) have an important role in buffering the pulsatile pressure generated from the left ventricle, which forwards continuous peripheral blood flow and protects the brain microcirculation from end-organ damage. Although compliance of distal conduit arteries (extremities' arteries) is attenuated by the nitric oxide synthase (NOS) inhibition, it is yet unknown whether compliance of proximal elastic arteries changes by the systemic NOS inhibition. To address this question, we measured central artery compliance in 17 young adults (26±1 years) who underwent intravenous infusions of N(G)-monomethyl-L-arginine (L-NMMA) or saline (placebo) on separate days. Following the systemic NOS inhibition, the mean arterial pressure (MAP), total peripheral resistance and aortic augmentation index were significantly increased. However, carotid artery compliance was not affected significantly (from 0.10±0.01 to 0.11±0.01 mm2) per mmHg) and the β-stiffness index (an index of arterial compliance adjusted for the distending pressure) tended to decrease (from 6.63±0.35 to 6.06±0.42 a.u., P=0.07). These parameters were not altered with saline infusion. Changes in the β-stiffness index tended to correlate negatively with the corresponding changes in MAP (r = -0.31, P=0.07). These results suggest that carotid artery compliance remains unchanged during the systemic NOS inhibition in spite of systemic vasoconstriction.

Aerobic exercise training increases plasma Klotho levels and reduces arterial stiffness in postmenopausal women

The Klotho gene is a suppressor of the aging phenomena, and the secretion as well as the circulation of Klotho proteins decrease with aging. Although habitual exercise has antiaging effects (e.g., a decrease in arterial stiffness), the relationship between Klotho and habitual exercise remains unclear. In the present study, we investigated the effect of habitual exercise on Klotho, with a particular focus on arterial stiffness. First, we examined the correlation between plasma Klotho concentration and arterial stiffness (carotid artery compliance and β-stiffness index) or aerobic exercise capacity [oxygen uptake at ventilatory threshold (VT)] in 69 healthy, postmenopausal women (50-76 years old) by conducting a cross-sectional study. Second, we tested the effects of aerobic exercise training on plasma Klotho concentrations and arterial stiffness. A total of 19 healthy, postmenopausal women (50-76 years old) were divided into two groups: control group and exercise group. The exercise group completed 12 wk of moderate aerobic exercise training. In the cross-sectional study, plasma Klotho concentrations positively correlated with carotid artery compliance and VT and negatively correlated with the β-stiffness index. In the interventional study, aerobic exercise training increased plasma Klotho concentrations and carotid artery compliance and decreased the β-stiffness index. Moreover, the changes in plasma Klotho concentration and arterial stiffness were found to be correlated. These results suggest a possible role for secreted Klotho in the exercise-induced modulation of arterial stiffness.

Singular and combined effects of nebivolol and lifestyle modification on large artery stiffness in hypertensive adults

We hypothesized that the combination of nebivolol and lifestyle modification would reduce large artery stiffness in middle-aged and older hypertensive adults more than either intervention alone. To address this, 45 men and women (age 40-75 years) with stage I hypertension were randomized to receive either nebivolol (NB; forced titration to 10 mg OD; n = 15; age 57.2 ± 11.4 years; body mass index [BMI] 30.8 ± 5.8 kg/m(2)), lifestyle modification (LM; 5-10% weight loss via calorie restriction and physical activity; n = 15; age 52.7 ± 8.5 years; BMI 33.9 ± 7.2 kg/m(2)) or nebivolol plus lifestyle modification (NBLM; n = 15; age 58.9 ± 9.4 years; BMI 32.5 ± 4.9 kg/m(2)) for 12 weeks. β-stiffness index, a blood-pressure-independent measure of arterial stiffness, and arterial compliance were measured via high-resolution ultrasound and tonometry at baseline and after the 12-week intervention. There was no difference between groups in age, body weight or composition, blood pressure, or in β-stiffness index or arterial compliance at baseline (all p > 0.05). Following the 12-week intervention, body weight decreased ~5% (p < 0.05) in the LM and NBLM groups but did not change from baseline in the NB group (p > 0.05). Supine brachial and carotid systolic and diastolic blood pressure declined following treatment in each of the groups (p < 0.05). However, the magnitude of reduction was not different (p < 0.05) between groups. β-stiffness index declined (-2.03 ± 0.60, -1.87 ± 0.83 and -2.51 ± 0.90 U) and arterial compliance increased similarly (both p > 0.05) in the NB, LM and NBLM groups, respectively. In summary, our findings indicate that the combination of nebivolol and lifestyle modification reduced large artery stiffness to a similar degree as either intervention alone in middle-aged and older hypertensive adults.

Arterial compliance and stiffness following low-intensity resistance exercise

Although acute high-intensity resistance exercise to exhaustion decreases arterial compliance and increases arterial stiffness, the effect of low-intensity resistance exercise (LRE) to exhaustion on arterial compliance and stiffness remains unknown. The present study investigated the acute effects of LRE on arterial compliance and stiffness. Ten healthy individuals (age 26 ± 5 years) performed LRE (40% of 1 repetition maximum) and control (CON: seated rest in the exercise room) trials on separate days in a randomized controlled crossover fashion. The LRE comprised three sets of bench presses to exhaustion with an inter-set rest period of 2 min. In the CON trial, LRE was not performed. Carotid arterial compliance, the β-stiffness index (via simultaneous B-mode ultrasound and applanation tonometry), carotid and brachial blood pressure and heart rate were measured before and at 30 and 60 min after both trials. Carotid arterial compliance and the β-stiffness index significantly increased and decreased, respectively (both P < 0.05), at 30 and 60 min after the LRE trials, but neither significantly differed after the CON trials. Carotid and brachial blood pressure and heart rate did not change at 30 and 60 min after both trials from baseline. These results suggest that LRE acutely increases arterial compliance and decreases arterial stiffness.

Variability and reproducibility of carotid structural and functional parameters assessed with transcutaneous ultrasound – Results from the SAPALDIA Cohort Study

ObjectiveCarotid intima media thickness (CIMT) and local stiffness are vascular biomarkers of atherosclerotic burden. We investigated the variability and reproducibility of clinically relevant structural (CIMT, lumen diameter) and functional parameters (strain, distensibility, compliance, β-stiffness index, Peterson's elastic modulus and Young's elastic modulus) measured in B-mode ultrasound sequences of the common carotid artery in the second follow up of the Swiss Cohort Study on Air Pollution and Lung and Heart Diseases In Adults (SAPALDIA3). MethodsUltrasound sequential images were examined twice over a 1 cm segment across at least one heart cycle in 165 SAPALDIA3 participants. To assess variability and reproducibility of structural and functional parameters, individual coefficients of variation (CV), intraclass correlation (ICC), Bland–Altman plots and mixed effect regressions were used. ResultsICCs of repeated examinations ranged between 0.67 and 0.77 for blood pressure indices, between 0.87 and 0.97 for structural properties and between 0.75 and 0.79 for functional parameters. CV was lowest in structural parameters (1.6–4.6%), followed by blood pressure (5.1–7.9%) and functional indices (11.0–13.1%). Variations in all parameters were predominantly explained by subjects (>74% in functional, >82% in structural properties). Bland–Altman plots for functional indices showed mean and standard deviation of the respective mean value of 4.2(19.6)% for strain, 1.9(24.4)% for distensibility, 2.4(22.2)% for compliance, 3.0(24.4)% for β-stiffness index, 0.9(25.7)% for Peterson's elastic modulus and 1.2(27.9)% for Young's elastic modulus. ConclusionThe results show that SAPALDIA3 measurements of transcutaneous ultrasound examinations have an excellent reproducibility of structural parameters and a good reproducibility of functional indices.