Effect of angiotensin II on pulse wave velocity in humans is mediated through angiotensin II type 1 (AT(1)) receptors

AT2R stimulation with C21 prevents arterial stiffening and endothelial dysfunction in the abdominal aorta from mice fed a high-fat diet

The aim of the present study was to evaluate the effect of Compound 21 (C21), a selective AT2R agonist, on the prevention of endothelial dysfunction, extracellular matrix (ECM) remodeling and arterial stiffness associated with diet-induced obesity (DIO). Five-week-old male C57BL/6J mice were fed a standard (Chow) or high-fat diet (HF) for 6 weeks. Half of the animals of each group were simultaneously treated with C21 (1 mg/kg/day, in the drinking water), generating four groups: Chow C, Chow C21, HF C, and HF C21. Vascular function and mechanical properties were determined in the abdominal aorta. To evaluate ECM remodeling, collagen deposition and TGF-β1 concentrations were determined in the abdominal aorta and the activity of metalloproteinases (MMP) 2 and 9 was analyzed in the plasma. Abdominal aortas from HF C mice showed endothelial dysfunction as well as enhanced contractile but reduced relaxant responses to Ang II. This effect was abrogated with C21 treatment by preserving NO availability. A left-shift in the tension-stretch relationship, paralleled by an augmented β-index (marker of intrinsic arterial stiffness), and enhanced collagen deposition and MMP-2/-9 activities were also detected in HF mice. However, when treated with C21, HF mice exhibited lower TGF-β1 levels in abdominal aortas together with reduced MMP activities and collagen deposition compared with HF C mice. In conclusion, these data demonstrate that AT2R stimulation by C21 in obesity preserves NO availability and prevents unhealthy vascular remodeling, thus protecting the abdominal aorta in HF mice against the development of endothelial dysfunction, ECM remodeling and arterial stiffness.

Neurohormones, inflammatory mediators, and cardiovascular injury in the setting of heart failure

Neurohormones and inflammatory mediators have effects in both the heart and the peripheral vasculature. In patients with heart failure (HF), neurohormonal activation and increased levels of inflammatory mediators promote ventricular remodeling and development of HF, as well as vascular dysfunction and arterial stiffness. These processes may lead to a vicious cycle, whereby arterial stiffness perpetuates further ventricular remodeling leading to exacerbation of symptoms. Although significant advances have been made in the treatment of HF, currently available treatment strategies slow, but do not halt, this cycle. The current treatment for HF patients involves the inhibition of neurohormonal activation, which can reduce morbidity and mortality related to this condition. Beyond benefits associated with neurohormonal blockade, other strategies have focused on inhibition of inflammatory pathways implicated in the pathogenesis of HF. Unfortunately, attempts to target inflammation have not yet been successful to improve prognosis of HF. Further work is required to interrupt key maladaptive mechanisms involved in disease progression.

Sympathetic neural modulation of arterial stiffness in humans

Elevated large-artery stiffness is recognized as an independent predictor of cardiovascular and all-cause mortality. The mechanisms responsible for such stiffening are incompletely understood. Several recent cross-sectional and acute experimental studies have examined whether sympathetic outflow, quantified by microneurographic measures of muscle sympathetic nerve activity (MSNA), can modulate large-artery stiffness in humans. A major methodological challenge of this research has been the capacity to evaluate the independent neural contribution without influencing the dynamic blood pressure dependence of arterial stiffness. The focus of this review is to summarize the evidence examining 1) the relationship between resting MSNA and large-artery stiffness, as determined by carotid-femoral pulse wave velocity or pulse wave reflection characteristics (i.e., augmentation index) in men and women; 2) the effects of acute sympathoexcitatory or sympathoinhibitory maneuvers on carotid-femoral pulse wave velocity and augmentation index; and 3) the influence of sustained increases or decreases in sympathetic neurotransmitter release or circulating catecholamines on large-artery stiffness. The present results highlight the growing evidence that the sympathetic nervous system is capable of modulating arterial stiffness independent of prevailing hemodynamics and vasomotor tone.

Hypovolemia and reduced hemoglobin mass in patients with heart failure and preserved ejection fraction

A fundamental tenet of heart failure (HF) pathophysiology hinges on a propensity for fluid retention leading to blood volume (BV) expansion and hemodilution. Whether this can be applied to heart failure patients with preserved ejection fraction (HFpEF) remains uncertain. The present study sought to determine BV status and key hormones regulating fluid homeostasis and erythropoiesis in HFpEF patients. BV and hemoglobin mass (Hb_mass) were determined with high‐precision, automated carbon monoxide (CO) rebreathing in 20 stable HFpEF patients (71.5 ± 7.3 years, left ventricular ejection fraction = 55.7 ± 4.0%) and 15 healthy age‐ and sex‐matched control individuals. Additional measurements comprised key circulating BV‐regulating hormones such as pro‐atrial natriuretic peptide (proANP), copeptin, aldosterone and erythropoietin (EPO), as well as central hemodynamics and arterial stiffness via carotid–femoral pulse wave velocity (PWV). Carotid–femoral PWV was increased (+20%) in HFpEF patients versus control individuals. With respect to hematological variables, plasma volume (PV) did not differ between groups, whereas BV was decreased (−14%) in HFpEF patients. In consonance with the hypovolemic status, Hb_mass was reduced (−27%) in HFpEF patients, despite they presented more than a twofold elevation of circulating EPO (+119%). Plasma concentrations of BV‐regulating hormones, including proANP (+106%), copeptin (+99%), and aldosterone (+62%), were substantially augmented in HFpEF patients. HFpEF patients may present with hypovolemia and markedly reduced Hb_mass, underpinned by a generalized overactivation of endocrine systems regulating fluid homeostasis and erythropoiesis. These findings provide a novel perspective on the pathophysiological basis of the HFpEF condition.

Multispecies Probiotic Supplementation Favorably Affects Vascular Function and Reduces Arterial Stiffness in Obese Postmenopausal Women-A 12-Week Placebo-Controlled and Randomized Clinical Study

Obesity in the postmenopausal period is associated with an increased risk of cardiovascular diseases in women. One of the key drivers of cardiovascular risk is endothelial dysfunction; thus, this is also a crucial point for studies on new therapeutic methods of cardioprotective properties. The aim of the current study was to evaluate the effect of two doses of multispecies probiotic Ecologic® Barrier supplement on functional (primary endpoint) and biochemical parameters (secondary endpoint) of endothelial dysfunction in obese postmenopausal women in a 12-week randomized, placebo-controlled clinical trial. A total of 81 obese Caucasian women participated in the trial. The subjects were randomly assigned to three groups that received a placebo, a low dose (LD) (2.5 × 10⁸ colony forming units (CFU) per day), or a high dose (HD) (1 × 1010 CFU per day) of lyophilisate powder containing live multispecies probiotic bacteria. The probiotic supplement was administered each day for 12 weeks in two equal portions. A high dose probiotic supplementation for 12 weeks decreased systolic blood pressure, vascular endothelial growth factor, pulse wave analysis systolic pressure, pulse wave analysis pulse pressure, pulse wave analysis augmentation index, pulse wave velocity, interleukin-6, tumor necrosis factor alpha, and thrombomodulin. Low doses of probiotic supplementation decreased the systolic blood pressure and interleukin-6 levels. The mean changes in the estimated parameters, compared among the three groups, revealed significant differences in the vascular endothelial growth factor, the pulse wave analysis systolic pressure, the pulse wave analysis augmentation index, the pulse wave velocity, the tumor necrosis factor alpha, and thrombomodulin. The post hoc tests showed significant differences for all parameters between HD and the placebo group, and HD and LD (besides pulse wave analysis augmentation index). We show for the first time that supplementation with multispecies probiotic Ecologic® Barrier favorably modifies both functional and biochemical markers of vascular dysfunction in obese postmenopausal women.

Acute Effects of Exercise Mode on Arterial Stiffness and Wave Reflection in Healthy Young Adults: A Systematic Review and Meta-Analysis

Background: This systematic review and meta-analysis quantified the effect of acute exercise mode on arterial stiffness and wave reflection measures including carotid-femoral pulse wave velocity (cf-PWV), augmentation index (AIx), and heart rate corrected AIx (AIx75). Methods: Using standardized terms, database searches from inception until 2017 identified 45 studies. Eligible studies included acute aerobic and/or resistance exercise in healthy adults, pre- and post-intervention measurements or change values, and described their study design. Data from included studies were analyzed and reported in accordance with the Cochrane Handbook for Systematic Reviews of Interventions and PRISMA guidelines. Meta-analytical data were reported via forest plots using absolute differences with 95% confidence intervals with the random effects model accounting for between-study heterogeneity. Reporting bias was assessed via funnel plots and, individual studies were evaluated for bias using the Cochrane Collaboration's tool for assessing risk of bias. A modified PEDro Scale was applied to appraise methodological concerns inherent to included studies. Results: Acute aerobic exercise failed to change cf-PWV (mean difference: 0.00 ms^-1 [95% confidence interval: -0.11, 0.11], p = 0.96), significantly reduced AIx (-4.54% [-7.05, -2.04], p = 0.0004) and significantly increased AIx75 (3.58% [0.56, 6.61], p = 0.02). Contrastingly, acute resistance exercise significantly increased cf-PWV (0.42 ms^-1 [0.17, 0.66], p = 0.0008), did not change AIx (1.63% [-3.83, 7.09], p = 0.56), and significantly increased AIx75 (15.02% [8.71, 21.33], p < 0.00001). Significant heterogeneity was evident within all comparisons except cf-PWV following resistance exercise, and several methodological concerns including low applicability of exercise protocols and lack of control intervention were identified. Conclusions: Distinct arterial stiffness and wave reflection responses were identified following acute exercise with overall increases in both cf-PWV and AIx75 following resistance exercise potentially arising fromcardiovascular and non-cardiovascular factors that likely differ from those following aerobic exercise. Future studies should address identified methodological limitations to enhance interpretation and applicability of arterial stiffness and wave reflection indices to exercise and health.

Haemodynamic and pulse wave responses to intravenous infusions of angiotensin II during chronic telmisartan therapy in normal volunteers

Introduction

This study investigated the central haemodynamic, blood pressure (BP) and pulse wave responses to progressively increasing infusion rates of intravenous angiotensin II (Ang II) in normal volunteers during chronic therapy with telmisartan or placebo.

Materials and methods

Ten normal volunteers, aged 21—33 years, completed a ramdomised, double-blind crossover study. Ang II was infused intravenously at increasing infusion rates (0—512 ng/minute) at the end of one week of telmisartan therapy (40—80 mg/day) and one week of placebo therapy. BP, central haemodynamics and pulse wave parameters were monitored continuous using a CardioDynamics Recorder, a Pulse Tracer Recorder and a Finipress Recorder.

Results

Baseline diastolic BP (5712 v G s. 67±13 mmHg) and pulse wave reflection ndex (RI) (38.4±18.6 vs. 60.6±12.5%) were significantly lower U on telmisartan than on placebo therapy. Cardiac index (CI), systolic BP, systemic vascular resistance index (SVRI), RI and pulse wave stiffness index (SI) were all significantly increased in a dose-dependent manner by Ang II on placebo therapy. Telmisartan significantly (p<0.05) attenuated all of these responses to Ang II. Increases in BP during Ang II infusion were associated with increases in SVRI and CI.

Conclusions

Telmisartan effectively blocked the effects of intravenous Ang II on CI, BP, RI and SI in healthy volunteers. Changes in CI make a major contribution to increase in BP response to intravenous Ang II in normal volunteers.

Effects of different types of antihypertensive agents on arterial stiffness: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

This system review and meta-analysis was conducted to systematically review and analyze the clinical benefits of different antihypertensive agents in improving arterial stiffness in hypertensive patients.

METHODS

PubMed database was searched for randomized controlled trials (RCTs) evaluating the effects of angiotensin receptor blockers (ARB) or other types of antihypertensive agents on pulse wave velocity (PWV). The main indicators were the improvements of PWV and augmentation index (AI) before and after randomized treatments with antihypertensive agents. For the studies that only provided the mean and standard deviation of the indicators before and after randomization, the standardized mean difference (SMD) method was directly applied to combine the mean and standard deviation of various indicators after the treatment. For the studies provided the mean and standard deviation of the changes of the indicators, the weighted mean difference (MD) method was applied to combine the mean and standard deviation of the therapeutic effect.

RESULTS

Ten RCT studies were included and the sample sizes range from 40 to 201 (total: 938). Four studies provided the changes of PWV before and after randomization, the pooled analysis showed that the changes of PWV in ARB group were not significantly higher than other antihypertensive agents [MD: 125.76, 95% confidence interval (CI): -78.70 to 330.23, P=0.23]; 4 studies provided the PWV values before and after randomization, the PWV values in ARB group were not significantly superior (SMD: 0.04, 95% CI: -0.16 to 0.24, P=0.71). Three studies provided the changes of AI before and after randomization, the ability of ARB to lower the level of the AI was superior to other antihypertensive agents (MD: 8.94, 95% CI: 2.18-5.71, P=0.01); 2 studies provided the AI value after randomization, the abilities of ARB and other anti-hypertensive agents to improve the AI were similar (SMD: 0.03, 95% CI: -1.20 to 1.26, P=0.06).

CONCLUSIONS

The effect of ARB on the improvement of the PWV level is not superior to other types of antihypertensive agents, but ARB is superior to other types of antihypertensive agents for improving the AI level. Overall, to improve of arterial stiffness, ARB maybe is superior to other antihypertensive agents.

Hypertension in Malaysia: An Analysis of Trends From the National Surveys 1996 to 2011

This study aimed to determine trends in prevalence, awareness, and control of hypertension in Malaysia and to assess the relationship between socioeconomic determinants and prevalence of hypertension in Malaysia.The distribution of hypertension in Malaysia was assessed based on available data in 3 National Health and Morbidity Surveys (NHMSs) and 1 large scale non-NHMS during the period of 1996 to 2011. Summary statistics was used to characterize the included surveys. Differences in prevalence, awareness, and control of hypertension between any 2 surveys were expressed as ratios. To assess the independent associations between the predictors and the outcome variables, regression analyses were employed with prevalence of hypertension as an outcome variable.Overall, there was a rising trend in the prevalence of hypertension in adults ≥30 years: 32.9% (30%-35.8%) in 1996, 42.6% (37.5%-43.5%) in 2006, and 43.5% (40.4%-46.6%) in 2011. There were significant increase of 32% from 1996 to 2011 (P < 0.001) and of 29% from 1996 to 2006 (P < 0.05), but only a small change of 1% from 2006 to 2011 (P = 0.6). For population ≥18 years, only a 1% increase in prevalence of hypertension occurred from the 2006 NHMS (32.2%) to the 2011 NHMS (32.7%) (P = 0.25). A relative increase of 13% occurred in those with primary education (P < 0.001) and a 15% increase was seen in those with secondary education (P < 0.001). The rate of increase in the prevalence of hypertension in the population with income level RM 3000-3999 was the highest (18%) during this period. In general, the older age group had higher prevalence of hypertension in the 2006 and 2011 NHMSs. The prevalence peaked at 74.1% among population aged 65 to 69 years in the 2011 NHMS. Both the proportion of awareness and the control of hypertension in Malaysia improved from 1996 to 2006. A change in the control of hypertension was 13% higher in women than in men.The findings suggest that the magnitude of hypertension in Malaysia needs additional attention. Strengthening the screening for hypertension in primary health-care settings in the high-risk groups and frequent health promotion to the community to enhance individual awareness and commitment to healthy living would be of immense value.

Prolonged blood pressure elevation following continuous infusion of angiotensin II-a baroreflex study in healthy humans

ANG II interacts with the sympathetic nervous system at central nervous blood pressure-regulating structures, including the baroreflex. It is unknown whether prolonged BP elevation mediated by high ANG II plasma levels could induce a persistent shift of the central nervous baroreflex setpoint, lasting beyond the short ANG II plasmatic half time of a few seconds, thereby consolidating elevated BP and/or increased SNA in healthy humans. In a blinded crossover design, ANG II or placebo (saline) was infused for a 6-h period in 12 resting normotensive students (6 males, 6 females) raising BP to borderline hypertensive levels. Between 60 and 120 min after the infusion period, muscle sympathetic nerve activity (MSNA) was assessed microneurographically and correlated with oscillometric BP measurements and heart rate at supine rest (baseline) and during pharmacologic baroreceptor challenge. Infusion of ANG II increased BP to borderline-hypertensive levels, as intended, whereas heart rate remained unaltered. At baroreflex assessment (i.e., 60-120 min after end of infusion period), systolic BP was significantly higher compared with placebo (Δ8.4 ± 3.1 mmHg; P < 0.05), whereas diastolic values were nearly equal between conditions. Baseline MSNA was neither decreased nor increased, and baroreflex sensitivity to vasoactive drug challenge was not altered. Our results show that elevation of ANG II plasma levels over 6 h was able to increase systolic, but not diastolic, BP far beyond blood-mediated ANG II effects. MSNA or heart rate did not counter-regulate this BP elevation, indicating that ANG II had sustainably reset the central nervous BP threshold of sympathetic baroreflex function to accept elevated BP input signals without counter-regulatory response.

Elevated brachial-ankle pulse wave velocity is independently associated with microalbuminuria in a rural population

Microalbuminuria is a marker of generalized endothelial dysfunction resulting from arterial stiffness or insulin resistance, and brachial-ankle pulse wave velocity (baPWV) is a good measure of arterial stiffness. We aimed to investigate whether elevated baPWV is independently associated with microalbuminuria. This study included 1,648 individuals aged over 40 who participated in the baseline Multi-Rural Cohort Study conducted in Korean rural communities between 2005 and 2006. Participants were classified into less than 30 mg/g as normoalbuminuria or 30-300 mg/g as microalbuminuriausing urinary albumin creatinine ratio (UACR). The median and Q1-Q3 baPWV values were significantly higher in the microalbuminuric group both in men (1,538, 1,370-1,777 cm/s vs. 1,776, 1,552-2,027 cm/s, P < 0.001) and women (1,461, 1,271-1,687 cm/s vs. 1,645, 1,473-1,915 cm/s, P < 0.001). BaPWV was independently associated with microalbuminuria in both genders after adjusting for pulse rate; fasting blood glucose; triglyceride; homeostatic model assessment insulin resistance (HOMAIR) and, history of hypertension and diabetes. Fasting blood sugar and HOMAIR were judged as having nothing to do with multicolinearity (r = 0.532, P < 0.001). Elevated baPWV was independently associated with microalbuminuria regardless of insulin resistance among rural subjects over 40 yr.

Assessment of arterial stiffness using applanation tonometry

Augmentation index (AIx) and pulse wave velocity (PWV) assess functional and structural aspects of the vascular wall and are independent markers of cardiovascular morbidity and mortality. Like blood pressure, many factors, genetic, structural, and physiological, affect AIx and PWV. AIx and PWV can be assessed noninvasively using applanation tonometry. The technique is simple, but comes with a number of practical and technical limitations that have not been well documented and (or) explored. This review considers pulse wave analysis in the context of cardiovascular disease, and considers its limitations. Data are presented indicating that the placement of the probe is critical, and that the amplitude of the obtained signal is related to the variability in measurements. On a more theoretical note, issues are discussed regarding the applied transfer functions that are built in the devices to assess central AIx from peripheral waveforms. Altogether, PWV and its analysis are useful additions to the arsenal of parameters that can be used to assess vascular health and to estimate vascular risk. Yet, our analysis underscores the necessity for precise operating procedures, and calls for transparency regarding the applied transfer functions of commercial devices.

Association of premature ventricular complexes with central aortic pressure indices and pulse wave velocity

BACKGROUND

Although premature ventricular complex (PVC) occurs frequently, its predisposing factors have rarely been studied. We examined the connection between PVC and aortic stiffness.

METHODS

We recruited 200 consecutive patients (< 50 years, 95 men, mean age 36 +/- 10 years) who received a 24-hour ambulatory electrocardiography examination for palpitation and PVC loads. Muscular artery pulse wave velocity (PWVm) and 4 main aortic pressure indices-augmented pressure, augmentation index (AI(x)), AI(x) corrected for a steady heart rate of 75 beat/min, and the extra workload-were measured, and atherosclerosis risk was evaluated.

RESULTS

Eighty-three (42%) patients had no PVC loads; 58 (29%) patients had low loads (< 24 beat/d), and 59 (29%) had high loads (> or = 24 beat/d). Only age and hyperlipidemia were significantly associated with PVC loads. Using a multivariate logistic regression model adjusted for potential confounders, we found that AI(x) (odds ratio [OR] 1.88, 95% CI 1.20-2.91, P = .005); augmented pressure (OR 1.57, 95% CI 1.02-2.43, P = .042); AI(x) corrected for a steady heart rate of 75 beat/min (OR 1.82, 95% CI 1.18-2.82, P = .007); and PWVm (OR 1.53, 95% CI 1.07-2.19, P = .021) were independent factors for PVC loads.

CONCLUSION

Increased central aortic pressure indices as well as PWVm were associated with increased PVC loads in young patients undergoing 24-hour ambulatory electrocardiography. Central aortic properties probably contributed to the occurrence of PVC.

[Effect of olmesartan medoxomil on arterial stiffness in patients with essential hypertension]

BACKGROUND AND OBJECTIVE

Arterial stiffness is one of the early lesions of the arteries in patients with cardiovascular risk factors. Pulse wave velocity (PWV) is one form of measurement of arterial stiffness. The renin-angiotensin system seems to be involved in the inflammatory mechanisms that take place at level of the vascular wall. The aim of this study is to investigate the effect of olmesartan (angiotensin II type 1 receptor antagonist) in the arterial stiffness, measuring the PWV. Another secondary objective is to determine the antihypertensive efficacy with ambulatory blood pressure monitoring (ABPM).

PATIENTS AND METHOD

Seventy-one patients with mild-to-moderate essential hypertension were consecutively included. Clinical blood pressure (CBP), ABPM and PWV, automatized measurement between the carotid and femoral arteries using the Complior device (Colson, Paris, France), were determined in a baseline and after 16 weeks of treatment with 10-40 mg of olmesartan.

RESULTS

Sixty-four patients completed the study. The mean (standard deviation) age was 48.31 (9.69) years and 44.9% were men. A significant reduction of the PWV was observed. The basal PWV was 10.50 (1.87) m/s and after treatment was 9.26 (1.84) m/s (p < 0.0001). We found only a positive correlation between the decline of PWV and diastolic blood pressure (BP). We could not find such correlation with systolic BP. The reduction degree was higher in the youngest patients where BP decrease was less evident. The BP decreased in a significant way (p < 0.0001) doing so in CBP and in the periods of 24 h, diurnal and nocturnal.

CONCLUSIONS

Olmesartan has shown effective to decrease the arterial stiffness, mainly in young patients. This effect seems to be independent of the decrease of the systolic BP. Olmesartan reduces effectively the BP during the 24 h.

Influence of the Angiotensin II Type I Receptor Gene 1166A > C Polymorphism on BP and Aortic Pulse Wave Velocity Among Malays

Angiotensin II type 1 receptor (AGT1R) gene 1166A > C polymorphism has been shown to be associated with essential hypertension and aortic stiffness as measured by carotid femoral pulse wave velocity (PWV). This study was carried out to investigate the association of the 1166A > C polymorphism with blood pressure (BP) and PWV among Malay hypertensive and normotensive subjects. Two hundred and one hypertensive subjects without evidence of cardiovascular (CV) complications and 201 age- and sex-matched normotensive subjects were studied in a cross-sectional design. Blood pressures (BP) and PWV were measured, and 1166A > C genotype was determined by polymerase chain reaction followed by restriction enzyme digestion. The 1166C allele frequency was 7.96% and 7.73% among Malay hypertensive and normotensive subjects, respectively. There was no association of the 1166A > C polymorphism with BP in the hypertensive, normotensive or overall Malay populations. PWV was significantly higher among 1166C allele carriers as compared to non-carriers (10.52 +/- 1.82 vs. 10.15 +/- 1.80, p = 0.040) in the overall population, but not in the hypertensive and normotensive populations separately. In conclusion, the frequency of 1166C polymorphism is similar among Malay hypertensive and normotensive subjects. This polymorphism has no association with BP but may have an influence on PWV in Malays, which needs further investigation.

Increase in aortic pulse wave velocity is associated with abnormal postprandial triglyceride response

BACKGROUND

Aortic pulse wave velocity (aPWV), an index of aortic distensibility, and postprandial hypertriglyceridemia are recognized as independent cardiovascular risk factors.

HYPOTHESIS

The aim of this study was to evaluate the relationship between postprandial hypertriglyceridemia and changes in aPWV.

METHODS

We prospectively studied 45 patients (mean age 48 [14] years, 28.9% men), who were submitted to a standardized fat meal (FM) test. According to their triglyceride (TG) levels 2, 4, 6, and 8 h after the FM, the patients were divided into two groups: Group 1 (31 patients) with postprandial TG levels < or = 219 mg/dl, and Group 2 (14 patients) with TG levels > 219 mg/dl at one of the aforementioned time intervals. Before and 6 h after the FM, aPWV was measured noninvasively.

RESULTS

Baseline characteristics in the two groups were similar, except for higher TG, pulse pressure, waist-to-hip ratio, percentage of patients who smoked or had arterial hypertension, and lower high-density lipoprotein cholesterol levels in Group 2. Postprandially, aPWV was higher in Group 2 [11.2(2.7) vs. 9.1(2.1) m/s, p = 0.004]. Changes in aPWV correlated with TG changes from baseline to 6 h after FM (r = 0.539, p < 0.001) and with the areas under the TG curve (r = 0.617, p < 0.001). A postprandial TG increase of 100 mg/dl resulted in a 0.88 m/s rise of aPWV.

CONCLUSION

An increase in aPWV 6 h after an FM test correlates positively with abnormal postprandial hypertriglyceridemia. These relationships, reported here for the first time, could be of practical use for better evaluation of patient prognosis.

Estimation of an age-specific reference interval for pulse wave velocity: a meta-analysis

OBJECTIVE

To estimate an age-specific reference interval for carotid-femoral pulse wave velocity (PWV), an index of aortic stiffness, and to determine the predictive values of the reference range for detecting those at moderate and high risk of cardiovascular disease (CVD).

DESIGN AND METHODS

We searched MEDLINE using PubMed from 1995 to 2005 for all studies in which Carotid-Femoral PWV was measured using a Complior (Colson, Paris, France) apparatus in Caucasian non-pregnant adults. Twenty-five studies were included, covering 30 groups of subjects; these groups were classified a priori into low (normal), moderate, and high CVD risk categories, with 2008, 5979, and 180 (total 8167) subjects, respectively. Individual-level data were simulated for each group, and an age-specific reference interval was calculated by using fractional polynomial functions.

RESULTS

We plotted an age-adjusted normal curve for PWV with 2.5, 5, 50, 90, 95, and 97.5 centile limits. Applying this reference interval to the moderate- and high-risk groups using simulations yielded sensitivities of 34.3 [95% confidence interval (CI) 33.2-35.3] and 57.2 (95% CI 55.2-59.3), respectively, specificities of 95.3 (95% CI 94.8-95.8) and 95.3 (95% CI 94.4-96.2), respectively, and positive likelihood ratios of 7.3 and 12.2, respectively.

CONCLUSION

We constructed an age-adjusted reference curve for PWV. Using the 95th centile of this curve as a threshold (e.g. 10.94, 11.86, and 13.18 m/s for 20, 40, and 60 years old) shows construct validity, as it appears to identify medium and high CVD risk groups reasonably accurately. This reference range needs to be tested using other datasets.

Dose Dependent Elevation of Plasma Tocotrienol Levels and Its Effect on Arterial Compliance, Plasma Total Antioxidant Status, and Lipid Profile in Healthy Humans Supplemented with Tocotrienol Rich Vitamin E

Tocotrienols are a class of vitamin E reported to be potent antioxidants, besides having the ability to inhibit the HMG-CoA reductase enzyme. This study assessed the effects of 3 doses of tocotrienol-rich vitamin E (TRE) on plasma tocotrienol isomer concentration, arterial compliance, plasma total antioxidant status (TAS), aortic systolic blood pressure (ASBP), serum total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) in healthy males.

METHODOLOGY

This randomised, blinded end-point, placebo-controlled clinical trial with a parallel design involved 36 healthy male subjects who took either an oral placebo or TRE at doses of 80, 160 or 320 mg daily for 2 mo. Baseline and end-of-treatment measurements of vitamin E concentration, arterial compliance [assessed by aortic femoral pulse wave velocity (PWV) and augmentation index (AI)], ASBP, plasma TAS, serum TC and LDL-C were taken.

RESULTS

Baseline tocotrienol isomer concentrations were low and not detectable in some subjects. Upon supplementation, all TRE-treated groups showed significant difference from placebo for their change in alpha, gamma and delta tocotrienol concentrations from baseline to end of treatment. There was a linear dose and blood level relationship for all the isomers. There was no significant difference between groups for their change in PWV, AI, plasma TAS, ASBP, TC or LDL-C from baseline to end of treatment. Groups 160 mg (p = 0.024) and 320 mg (p = 0.049) showed significant reductions in their ASBP. Group 320 mg showed a significant 9.2% improvement in TAS.

CONCLUSION

TRE at doses up to 320 mg daily were well tolerated. Treatment significantly increased alpha, delta, and gamma tocotrienol concentrations but did not significantly affect arterial compliance, plasma TAS, serum TC or LDL-C levels in normal subjects.

Effects of valsartan and perindopril combination therapy on left ventricular hypertrophy and aortic arterial stiffness in patients with essential hypertension

OBJECTIVE

To compare the effects of combined therapy of an angiotensin II receptor blocker (ARB; valsartan) and an angiotensin converting enzyme inhibitor (ACEI; perindopril) on blood pressure (BP), metabolic profiles, plasma brain natriuretic peptide (BNP) levels, echocardiographic findings, and aortic pulse wave velocity (PWV) with those of respective monotherapy in never-treated patients with essential hypertension.

METHODS

This was a prospective randomized trial, in which there were 31 patients with essential hypertension and left ventricular hypertrophy (LVH) who visited the outpatient clinic of Oita Red Cross Hospital (14 women and 17 men; mean+/-SD age, 59+/-5 years). Each patient was randomly assigned to receive valsartan (160 mg/day, V group, n=10), perindopril (8 mg/day, P group, n=11), or a combination of valsartan (80 mg/day) and perindopril (4 mg/day, V+P group, n=10) for 40 weeks. Ambulatory BP monitoring (ABPM), echocardiographic findings, metabolic findings, plasma BNP levels, and brachial-ankle PWV (baPWV) were evaluated before and after the 40-week therapy.

RESULTS

The baseline and post-therapeutic BP levels were similar among the three groups. At baseline ABPM, non-dipping was observed in 80, 82, and 80% in the V, P, and V+P groups, respectively. Each 40-week therapy regimen comparably reduced ABP. The plasma BNP levels (P<0.0001 for each), left ventricular mass index (LVMI) (P<0.01 for each), and PWV values (P<0.0001 for each) were also reduced. However, when compared with either V or P group, the percentage reduction in LVMI (P<0.05 and P<0.005, respectively), BNP (P<0.05 for each), and baPWV values (P<0.005 and P<0.001, respectively) was greater in the V+P group.

CONCLUSIONS

Our findings suggest that, when compared with each monotherapy, perindopril and valsartan combination therapy exerts greater beneficial effects regarding the regression of LVH, reduction in BNP, and improvement of PWV in a selected group of essential hypertensive patients with LVH and high prevalence of non-dipping patterns.

Marinobufagenin may mediate the impact of salty diets on left ventricular hypertrophy by disrupting the protective function of coronary microvascular endothelium

Individuals who eat salty diets and who are "salt-sensitive" tend to have increased left ventricular mass, independent of blood pressure; this phenomenon awaits an explanation. It is clear that local up-regulation of angiotensin II (AngII) production and activity play a key role in the induction of left ventricular hypertrophy (LVH). Recent evidence suggests that a healthy coronary microvascular endothelium opposes this effect by serving as a paracrine source of nitric oxide (NO), a natural antagonist of AngII activity, and that up-regulation of this mechanism can account for the protective role of bradykinin with respect to LVH. The coronary microvasculature also possesses NAD(P)H oxidase activity that can generate superoxide, inimical to the bioactivity of endothelial NO. There is now good reason to believe that the triterpenoid marinobufagenin (MBG), a selective inhibitor of the alpha-1 isoform of the sodium pump, mediates the impact of salty diets on blood pressure; production of MBG by the adrenal cortex is boosted when salt-sensitive animals are fed salty diets. It is hypothesized that coronary microvascular endothelium expresses the alpha-1 isoform of the sodium pump, and that MBG thus can target this endothelium. If that is the case, MBG would be expected to decrease membrane potential in these cells; as a consequence, superoxide production would be up-regulated, NO synthase activity would be down-regulated, and myocardial NO bioactivity would thus be suppressed. This would offer a satisfying explanation for the impact of salt and salt-sensitivity on risk for LVH. If expression of the alpha-1 isoform of the sodium pump is a more general property of vascular endothelium, MBG may suppress NO bioactivity in other regions of the vascular tree, thereby contributing to other adverse effects elicited by salty diets: reduced arterial compliance, medial hypertrophy, impaired endothelium-dependent vasodilation, hypertensive/diabetic glomerulopathy, increased risk for stroke, and hypertension.

Angiotensin receptor blockade in the challenging era of systolic hypertension

Systolic blood pressure is a major cardiovascular risk factor which is often associated with arterial stiffness. Markers of arterial stiffness, such as pulse pressure and carotid-femoral pulse wave velocity, have been proved independent predictors of cardiovascular risk. Recent evidence suggests that the renin-angiotensin system is involved in the pathogenesis of systolic hypertension and arterial stiffness. Outcome trials have shown impressive cardiovascular protection by reducing systolic blood pressure (BP) with drug treatment. However, in clinical practice systolic hypertension remains largely uncontrolled, first, because systolic BP goal is more difficult to be reached than diastolic and, second, because physicians are often reluctant to intensify treatment in patients with systolic BP close to 150 mmHg. Recent trials have focused on the effects of antihypertensive drugs not only on blood pressure, but also on pulse pressure and pulse-wave velocity. Blockade of the renin-angiotensin-aldosterone system, using angiotensin-converting enzyme inhibitors and more recently angiotensin receptor blockers, has been shown to provide beneficial effects on arterial stiffness that appear to be independent of their antihypertensive effects. Recent outcome trials have shown significant cardiovascular protection with angiotensin receptor blockers. These drugs have an excellent placebolike profile of adverse effects which is maintained when these drugs are combined with low-dose diuretics. Therefore, an angiotensin receptor blocker-based treatment strategy appears to be an attractive and evidence-based approach for the management of systolic hypertension, the reduction of arterial stiffness and the prevention of cardiovascular disease.

Arterial stiffness and the systolic hypertension syndrome

PURPOSE OF REVIEW

This review is intended to provide the background for a new comprehensive hemodynamic view of the syndrome of systolic or wide pulse pressure hypertension and its hallmark abnormality: increased central arterial stiffness.

RECENT FINDINGS

Studies of the pathogenesis of systolic hypertension have lagged. This review describes the systolic hypertension syndrome as a complex set of hemodynamic maladaptations that include stiff central arteries, normal peripheral arteries with variable pressure amplification characteristics, arteriolar constriction, microcirculatory rarefaction, metabolic abnormalities, cardiac hypertrophy, and increased blood pressure variability. Because the structural and functional properties of arteries of different caliber are highly heterogeneous and vary with aging and disease, simple measurements such as standard brachial artery blood pressure, brachial pulse pressure, or mean arterial pressure are inadequate to provide meaningful insight into the pathophysiology of the syndrome. Additional parameters developed to describe changes in arterial mechanics (arterial compliance or stiffness, elastic modulus, impedance, pulse wave velocity, augmentation index, and pulse pressure amplification) are intrinsically limited and are directly or indirectly pressure-dependent. Quantitation of central arterial stiffness provides a modest increment in cardiovascular and renal risk stratification.

SUMMARY

Better clinical management of systolic hypertension depends on greater insight into the syndrome as a whole, more critical analysis of existing techniques, and the development of new approaches.

Marinobufagenin may mediate the impact of salty diets on left ventricular hypertrophy by disrupting the protective function of coronary microvascular endothelium

Individuals who eat salty diets and who are "salt-sensitive" tend to have increased left ventricular mass, independent of blood pressure; this phenomenon awaits an explanation. It is clear that local up-regulation of angiotensin II (AngII) production and activity play a key role in the induction of left ventricular hypertrophy (LVH). Recent evidence suggests that a healthy coronary microvascular endothelium opposes this effect by serving as a paracrine source of nitric oxide (NO), a natural antagonist of AngII activity, and that up-regulation of this mechanism can account for the protective role of bradykinin with respect to LVH. The coronary microvasculature also possesses NAD(P)H oxidase activity that can generate superoxide, inimical to the bioactivity of endothelial NO. There is now good reason to believe that the triterpenoid marinobufagenin (MBG), a selective inhibitor of the alpha-1 isoform of the sodium pump, mediates the impact of salty diets on blood pressure;production of MBG by the adrenal cortex is boosted when salt-sensitive animals are fed salty diets. It is hypothesized that coronary microvascular endothelium expresses the alpha-1 isoform of the sodium pump, and that MBG thus can target this endothelium. If that is the case, MBG would be expected to decrease membrane potential in these cells;as a consequence, superoxide production would be up-regulated, NO synthase activity would be down-regulated, and myocardial NO bioactivity would thus be suppressed. This would offer a satisfying explanation for the impact of salt and salt-sensitivity on risk for LVH. If expression of the alpha-1 isoform of the sodium pump is a more general property of vascular endothelium, MBG may suppress NO bioactivity in other regions of the vascular tree, thereby contributing to other adverse effects elicited by salty diets: reduced arterial compliance, medial hypertrophy, impaired endothelium-dependent vasodilation, hypertensive/diabetic glomerulopathy, increased risk for stroke, and hypertension.

Efficacy of Various Antihypertensive Agents as Evaluated by Indices of Vascular Stiffness in Elderly Hypertensive Patients

When observed in elderly hypertensive patients, increased pulse pressure (PP) and arterial stiffness are known to be independent risk factors for cardiovascular diseases. Increased systolic blood pressure (SBP) leads to left ventricular hypertrophy, while decreased diastolic blood pressure (DBP) results in decreased coronary circulation. It is known that increased arterial stiffness is the major cause of increased PP. Thus basic morbid states of cardiac failure or ischemic heart diseases are more likely to develop in elderly hypertensive patients with increased PP and arterial stiffness, and there is need of antihypertensive drugs that decrease these effects in elderly hypertensives. In this study, we compared the effects of an angiotensin-receptor blocker (ARB: valsartan), an angiotensin-converting enzyme inhibitor (ACE-I: temocapril), and long-acting Ca antagonists (L- and N-type Ca channel blocker: cilnidipine; and L-type Ca channel blocker: nifedipine CR) on PP and arterial stiffness measured by pulse wave velocity in elderly hypertensive patients for 3 months. The ARB yielded the largest reductions in PP and brachial-ankle pulse wave velocity (baPWV), followed by the ACE-I and L- and N-type Ca channel blocker, while the L-type Ca channel blocker yielded no improvement. The effects on arterial stiffness and PP thus varied among the drug characteristics. Although ARB achieved the largest reduction in baPWV, this decrease was not associated with any reductions in PP, SBP, DBP, or mean blood pressure, as were the baPWV-decreases achieved by the other drugs, suggesting that ARB may further reduce the risk of arteriosclerosis in elderly hypertensive patients by decreasing arterial stiffness in addition to its antihypertensive effect.