Age dependency of central and peripheral systolic blood pressures: Cross-sectional and longitudinal observations in European populations

Plasma Metabolome Predicts Aortic Stiffness and Future Risk of Coronary Artery Disease and Mortality After 23 Years of Follow-Up in the General Population

BACKGROUND

Increased aortic stiffness (arteriosclerosis) is associated with early vascular aging independent of age and sex. The underlying mechanisms of early vascular aging remain largely unexplored in the general population. We aimed to investigate the plasma metabolomic profile in aortic stiffness (vascular aging) and associated risk of incident cardiovascular disease and mortality.

METHODS AND RESULTS

We included 6865 individuals from 2 Swedish population-based cohorts. Untargeted plasma metabolomics was performed by liquid-chromatography mass spectrometry. Aortic stiffness was assessed directly by carotid-femoral pulse wave velocity (PWV) and indirectly by augmentation index (AIx@75). A least absolute shrinkage and selection operator (LASSO) regression model was created on plasma metabolites in order to predict aortic stiffness. Associations between metabolite-predicted aortic stiffness and risk of new-onset cardiovascular disease, cardiovascular mortality, and all-cause mortality were calculated. Metabolite-predicted aortic stiffness (PWV and AIx@75) was positively associated particularly with acylcarnitines, dimethylguanidino valeric acid, glutamate, and cystine. The plasma metabolome predicted aortic stiffness (PWV and AIx@75) with good accuracy (R2=0.27 and R2=0.39, respectively). Metabolite-predicted aortic stiffness (PWV and AIx@75) was significantly correlated with age, sex, systolic blood pressure, body mass index, and low-density lipoprotein. After 23 years of follow-up, metabolite-predicted aortic stiffness (PWV and AIx@75) was significantly associated with increased risk of new-onset coronary artery disease, cardiovascular mortality, and all-cause mortality.

CONCLUSIONS

Aortic stiffness is associated particularly with altered metabolism of acylcarnitines, cystine, and dimethylguanidino valeric acid. These metabolic disturbances predict increased risk of new-onset coronary artery disease, cardiovascular mortality, and all-cause mortality after more than 23 years of follow-up in the general population.

Maternal pregnancy weight or gestational weight gain and offspring's blood pressure: A systematic review

AIMS

An increasing number of studies suggest that maternal weight parameters in pregnancy are associated with offspring's blood pressure (BP). The aim of this systematic review - following the updated Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) Statement - was to assess and judge the evidence for an association between maternal pregnancy weight/body mass index (BMI) or gestational weight gain (GWG) with offspring's BP in later life.

DATA SYNTHESIS

MEDLINE, EMBASE, Cochrane Library, CINAHL and Web of Science were searched without limits. Risk of bias was assessed using the "US National Heart, Lung and Blood Institute"-tool, and an evidence grade was allocated following the "World Cancer Research Fund" criteria. Of 7,124 publications retrieved, 16 studies (all cohort studies) were included in the systematic review. Overall data from 52,606 participants (0 years [newborns] to 32 years) were enclosed. Association between maternal pregnancy BMI and offspring's BP were analyzed in 2 (both "good-quality" rated) studies, without consistent results. GWG and offspring's BP was analyzed in 14 studies (2 "good-quality", 9 "fair-quality", 3 "poor-quality" rated). Of these, 3 "fair-quality" studies described significant positive results for systolic BP and significant results, but partly with varying directions of effect estimates for diastolic BP. Mean arterial pressure (MAP) was analyzed in 1 "poor-quality" congress paper. Overall, based on the small number of "good-quality"-rated studies and the inconsistency of effect direction, no firm conclusion can be drawn.

CONCLUSION

Evidence for an association of maternal pregnancy weight determinants with offspring's BP was overall graded as "limited - no conclusion".

High-frame-rate A-mode ultrasound for calibration-free cuffless carotid pressure: feasibility study using lower body negative pressure intervention

PURPOSE

Existing technologies to measure central blood pressure (CBP) intrinsically depend on peripheral pressure or calibration models derived from it. Pharmacological or physiological interventions yielding different central and peripheral responses compromise the accuracy of such methods. We present a high-frame-rate ultrasound technology for cuffless and calibration-free evaluation of BP from the carotid artery. The system uses a pair of single-element ultrasound transducers to capture the arterial diameter and local pulse wave velocity (PWV) for the evaluation of beat-by-beat BP employing a novel biomechanical model.

MATERIALS AND METHODS

System's functionality assessment was conducted on eight male subjects (26 ± 4 years, normotensive and no history of cardiovascular risks) by perturbing pressure via short-term moderate lower body negative pressure (LBNP) intervention (-40 mmHg for 1 min). The ability of the system to capture dynamic responses of carotid pressure to LBNP was investigated and compared against the responses of peripheral pressure measured using a continuous BP monitor.

RESULTS

While the carotid pressure manifested trends similar to finger measurements during LBNP, the system also captured the differential carotid-to-peripheral pressure response, which corroborates the literature. The carotid diastolic and mean pressures agreed with the finger pressures (limits-of-agreement within ±7 mmHg) and exhibited acceptable uncertainty (mean absolute errors were 2.4 ± 3.5 and 2.6 ± 4.0 mmHg, respectively). Concurrent to the literature, the carotid systolic and pulse pressures (PPs) were significantly lower than those of the finger pressures by 11.1 ± 9.4 and 11.3 ± 8.2 mmHg, respectively (p < .0001).

CONCLUSIONS

The study demonstrated the method's potential for providing cuffless and calibration-free pressure measurements while reliably capturing the physiological aspects, such as PP amplification and dynamic pressure responses to intervention.

The Influence of Resting Heart Rate on Central Pulse Pressure is Age-Dependent

INTRODUCTION

Low resting heart rate (RHR) increases augmentation pressure (AP) and central pulse pressure (central PP) and decreases peripheral pressure wave amplification. Given that the contribution of AP to central PP increases with age we hypothesized that the influence of RHR on AP, central PP and peripheral amplification varies with age.

AIM

To evaluate the interaction between age and RHR on the forward and backward components of central PP.

METHODS

A cohort of 1249 ambulatory hypertensive patients with good quality radial wave recordings was stratified into age groups and quartiles of RHR (< 61, 61-68, 69-76 and > 76 bpm). Central aortic pressure was estimated from radial applanation tonometry.

RESULTS

Forward wave (FW) and AP showed opposite changes until midlife, mutually canceling their effect on central PP, whereas both components of central PP increased in parallel after the fifth decade. The initial fall in FW was expressed in the brachial artery as a corresponding decrease in PP and in peripheral amplification. After midlife there was a further decrease in peripheral amplification at the expense of the rise in central PP. A lower RHR exaggerated the age-related increase in left ventricular ejection time (LVET), AP, central PP, and the decrease in peripheral amplification (P < 0.001, for all the interactions between decades and quartiles of RHR). Multivariable regression analyses (n = 1249) confirmed a significant interaction between age and RHR on central PP (P < 0.001), AP (P < 0.001), LVET (P < 0.001), AIx (P < 0.035), and peripheral amplification (P < 0.001). Multivariable regression analyses stratified by age groups (< 30, 30-59 and ≥ 60 years) showed an increasing strength in the relationship of RHR with AP, independently of sex, mean arterial pressure, pulse wave velocity and beta-blockers use. The average increase in AP for a decrease in 10 bpm was 1.4 mmHg before age < 30 years; 2.5 mmHg between age 30-59 years; and 5.4 mmHg at 60 years and older.

CONCLUSIONS

A lower heart rate exaggerated AP and central PP in an age dependent fashion, being the effect particularly relevant in older patients.

Smokeless tobacco use: its prevalence and relationships with dental symptoms, nutritional status and blood pressure among rural women in Burkina Faso

BACKGROUND

Sub-Saharan women use smokeless tobacco (SLT) more than smoked tobacco. Among Western African countries, the estimated weighted prevalence of SLT use in rural women was found to be the highest in Burkina Faso (after Sierra Leone). This study aimed to assess the prevalence of SLT use and its associated factors among rural women in Burkina Faso by using nationally representative data.

METHODS

We used data from the 2013 STEPwise approach to Surveillance (STEPS) study, which provided sociodemographic, clinical (anthropometric, systolic blood pressure [SBP], diastolic blood pressure [DBP] and dental symptoms), biological (total and high-density lipoprotein cholesterol and fasting blood sugar), and tobacco and alcohol consumption data. Data for 1730 rural women were used, and we performed Student's chi-squared and logistic regression analyses.

RESULTS

The prevalence of current SLT use was 13.8% (95% CI: 12.2-15.5). Significant risks for SLT use were the presence of dental symptoms (adjusted odds ratio [aOR] = 2.59; p < 0.001), undernourishment (aOR = 1.78; p < 0.01), decreased waist circumference (aOR = 0.98; p < 0.05), decreased DBP (aOR = 0.97; p < 0.01), increased SBP (aOR = 1.01; p < 0.05), and increased differential blood pressure (aOR = 1.01; p < 0.05). The co-use of alcohol was also a significant risk factor (aOR = 2.80; p < 0.001).

CONCLUSION

The prevalence of current SLT use was high among rural women in Burkina Faso, and significant concerns for users included alcohol co-use, the occurrence of dental symptoms, undernourishment, and an increase in differential blood pressure. National Public Health interventions are needed to reduce SLT use and its health-related concerns.

Impact of age on the association between 24-h ambulatory blood pressure measurements and target organ damage

OBJECTIVE

The aim of this study was to evaluate the impact of age on the associations between hemodynamic components derived from 24-h ambulatory blood pressure (24-h ABPM) and target organ damage, in apparently healthy, nonmedicated individuals.

METHODS

Twenty-four-hour ABPM and target organ damage (left ventricular mass index, pulse wave velocity, urine albumin : creatinine ratio and carotid atherosclerotic plaques) were evaluated in 1408 individuals. Associations were examined in regression models, stratified for age [middle-aged (41 or 51 years) or elderly (61 or 71 years)], and adjusted for sex, smoking status, and total-cholesterol.

RESULTS

In middle-aged individuals, an increase of 10 mmHg in 24-h SBP was independently associated with an increase of 3.8 (2.7-4.8) g/m in LVMI. The effect was nearly doubled in the elderly subgroup, where the same increase resulted in an increase in LVMI of 6.3 (5.0-7.6) g/m (P for interaction <0.01). An increase of 10 mmHg of 24-h SBP was associated with a 6.7% increase in pulse wave velocity in middle-aged individuals and with an 9.1% increase in elderly individuals (P for interaction <0.01). An independent association between 24-h ABPM and urine albumin : creatinine ratio was only observed in the elderly subgroup. Associations between the presence of atherosclerotic plaques and components from 24-h ABPM except 24-h DBP were not modified by age (all P for interaction >0.26).

CONCLUSION

Age enhances the associations between hemodynamic components obtained from 24-h ABPM and measures of arterial stiffness, microvascular damage, and cardiac structure, but not atherosclerosis.

Maternal prepregnancy BMI or weight and offspring's blood pressure: Systematic review

Emerging evidence suggests that maternal prepregnancy body mass index or weight (MPBW) may be associated with offspring's blood pressure (BP). Therefore, we conducted a systematic review-following the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement-to assess and judge the evidence for an association between MPBW with offspring's later BP. Five data bases were searched without limits. Risk of bias was assessed using the "Tool to Assess Risk of Bias in Cohort Studies," and an evidence grade was allocated following the World Cancer Research Fund criteria. Of 2,011 publications retrieved, 16 studies (all cohort studies) were included in the systematic review; thereof, 5 studies (31%) were rated as good-quality studies. Overall, data from 63,959 participants were enclosed. Systolic BP was analysed in 15 (5 good quality), diastolic BP in 12 (3 good quality), and mean arterial pressure in 3 (no good quality) studies. Five good-quality studies of MPBW with offspring's systolic BP as the outcome and 1 good-quality study with offspring's diastolic BP as the outcome observed a significant association. However, after adding offspring's anthropometry variables to the statistical model, the effect attenuated in 4 studies with systolic BP to nonsignificance, the study with diastolic BP remained significant. No good-quality studies were found with respect to offspring's later mean arterial pressure. In conclusion, this systematic review found suggestive, but still limited, evidence for an association between MPBW with offspring's later BP. The available data suggest that the effect might be mainly mediated via offspring's anthropometry.

American Society of Hypertension position paper: central blood pressure waveforms in health and disease

A number of devices are available which noninvasively estimate central aortic blood pressure using a variety of approaches such as tonometry or oscillometry. In this position paper, we discuss how the central pressure waveform is generated and measured, how central pressure waveforms appear in health and disease, the predictive value of central blood pressure measurements, the effects of interventions on waveforms, and areas of future need in this field of clinical and research endeavor.

Prospective risk factors for increased central augmentation index in men and women

BACKGROUND

Arterial wave reflections are important determinants of central pressure pulsatility and left ventricular afterload. The augmentation index (AIx) is the most widely used surrogate of arterial wave reflections. Despite multiple cross-sectional studies assessing the correlates of AIx, little prospective data exist regarding changes in AIx over time. We aimed to assess the predictors of changes in AIx over time in adults from the general population.

METHODS

We performed radial arterial tonometry assessments a median of 3.18 ± 0.4 years apart on 143 nondiabetic adult participants in the population-based PREVENCION study. Central AIx was obtained using the generalized transfer function of the Sphygmocor device.

RESULTS

Predictors of the change in AIx over time were investigated. Among men (n = 67), the change in AIx was predicted by abdominal obesity (standardized β for waist circumference = 0.34; P = 0.002), impaired fasting glucose (standardized β = 0.24; P = 0.009), and the change in heart rate (standardized β = -0.78; P < 0.001). Among women (n = 76), the change in AIx was predicted by non-high-density lipoprotein cholesterol (standardized β = 0.33; P = 0.001), C-reactive protein levels (standardized β = 0.24; P = 0.02), change in mean arterial pressure (standardized β = 0.33; P = 0.001), and change in heart rate (standardized β = -0.52; P < 0.001).

CONCLUSIONS

Metabolic and inflammatory factors predicted changes in AIx over time, with important sex differences. Metabolic factors, such as abdominal obesity and impaired fasting glucose, predicted changes in AIx in men, whereas C-reactive protein and non-high-density lipoprotein cholesterol levels predicted changes in women. Our findings highlight the impact of sex on arterial properties and may guide the design of interventions to favorably impact changes in late systolic pressure augmentation.

β-Blockers

Objective: To review the pharmacology, pharmacokinetics, and pharmacodynamic properties of commonly used β-blockers (atenolol, carvedilol, metoprolol succinate, metoprolol tartrate, and nebivolol). Data Sources: A MEDLINE literature search (1966-May 2013) was performed using the following key terms: hypertension, β-blockers, atenolol, carvedilol, metoprolol tartrate, metoprolol succinate, nebivolol, pharmacology, pharmacodynamics, pharmacokinetics, blood pressure, metabolic, lipid, central aortic pressure, diabetes, and insulin resistance. References from publications reviewed were included. Study Selection and Data Extraction: English-language articles identified were reviewed. Animal studies and studies in patients for a primary diagnosis of coronary artery disease were excluded. Data Synthesis: β-Blockers are no longer recommended first-line therapy for primary hypertension, based on data showing that β-blockers are inferior to other antihypertensives and no better than placebo, in spite of provision of blood pressure reduction. Because atenolol is the β-blocker used in 75% of these studies, uncertainty about widespread application to all β-blockers exists. Different pharmacological and physiological properties, both within β-blockers and compared with other antihypertensives, may explain divergent effects. Evidence shows that β-blockers have a truncated effect on central aortic pressure, an independent predictor of cardiovascular events, compared with other antihypertensive classes; differences within the class may exist, but the evidence is inconclusive. Metabolic effects differ within the β-blocker class, with evidence that carvedilol causes less metabolic dysregulation. Conclusion: Emerging evidence reveals physiological differences within the β-blocker class and in comparison to other antihypertensives. These differences provide insight into the diverse clinical effects β-blockers provide in cardiovascular disease.

Outcome-driven thresholds for ambulatory pulse pressure in 9938 participants recruited from 11 populations

Evidence-based thresholds for risk stratification based on pulse pressure (PP) are currently unavailable. To derive outcome-driven thresholds for the 24-hour ambulatory PP, we analyzed 9938 participants randomly recruited from 11 populations (47.3% women). After age stratification (<60 versus ≥60 years) and using average risk as reference, we computed multivariable-adjusted hazard ratios (HRs) to assess risk by tenths of the PP distribution or risk associated with stepwise increasing (+1 mm Hg) PP levels. All adjustments included mean arterial pressure. Among 6028 younger participants (68 853 person-years), the risk of cardiovascular (HR, 1.58; P=0.011) or cardiac (HR, 1.52; P=0.056) events increased only in the top PP tenth (mean, 60.6 mm Hg). Using stepwise increasing PP levels, the lower boundary of the 95% confidence interval of the successive thresholds did not cross unity. Among 3910 older participants (39 923 person-years), risk increased (P≤0.028) in the top PP tenth (mean, 76.1 mm Hg). HRs were 1.30 and 1.62 for total and cardiovascular mortality, and 1.52, 1.69, and 1.40 for all cardiovascular, cardiac, and cerebrovascular events. The lower boundary of the 95% confidence interval of the HRs associated with stepwise increasing PP levels crossed unity at 64 mm Hg. While accounting for all covariables, the top tenth of PP contributed less than 0.3% (generalized R(2) statistic) to the overall risk among the elderly. Thus, in randomly recruited people, ambulatory PP does not add to risk stratification below age 60; in the elderly, PP is a weak risk factor with levels below 64 mm Hg probably being innocuous.

Brachial artery tonometry and the Popeye phenomenon: explanation of anomalies in generating central from upper limb pressure waveforms

BACKGROUND

Noninvasive applanation tonometry studies of the brachial and radial artery pressure waves show that the arterial pulse is substantially amplified between the brachial and radial sites. Brachial tonometry waveforms have also been used to calibrate carotid tonometry waves as a measure of central pressure in major clinical trials. These trials assume identity of mean and of DBP in calculation of central (carotid) SBP. None of these trials showed superiority of central over brachial pressure in predicting outcome, but all showed equivalence of SBP and pulse pressure at brachial and carotid sites!

METHOD

We tested this method by measuring pressure waves at brachial, radial and carotid sites by applanation tonometry in 100 patients, with attention to any subtle difference between brachial and radial waveforms, and with both calibrated to cuff SBP and DBP.

RESULTS

The results confirmed no proximal and strong distal amplification in the arm. However, this was accompanied by blunting of the brachial compared with radial waveform with brachial pressure 2.7 mmHg higher during most of the cardiac cycle. Form factor of the ensemble-averaged brachial wave [39.1 standard deviation (SD) 4.9%] was similar to the carotid (40.2 SD 4.1%) but different to the radial wave (34.8 SD 3.7%; P < 0.01).

CONCLUSIONS

All findings were explained by inability to applanate the brachial artery, and resulting systematic error in generating brachial waveforms. In estimation of central pressure with applanation tonometry, the radial pressure wave, which can be accurately applanated, should be used, and calibrated to the brachial cuff.

Cross-sectional and longitudinal assessment of arterial stiffening with age in European and chinese populations

As arteries become stiffer with aging, reflected waves move faster and augment late systolic pressure. Few studies have described the age-related changes in both peripheral and central systolic blood pressures in populations. We investigated the age dependency of peripheral (pSBP) and central (cSBP) systolic pressure and pressure amplification (i.e., difference between peripheral and central SBP) in randomly selected participants from European and Chinese populations. Data were collected in 1420 Europeans (mean age, 41.7 years) and 2044 (mean age, 45.1 years) Chinese. In cross-sectional analyses of the population samples cSBP consistently increased more with age than pSBP with the age-related increases being greater in women than men. Repeat assessment of pSBP and cSBP in 398 Europeans and 699 Chinese at a median interval approximately 4 years of follow-up confirmed that also within subjects cSBP rose steeper with aging than pSBP. In conclusion, with aging, pSBP approximates to cSBP. This might explain why in older subjects pSBP becomes the main predictor of cardiovascular complications.

Arterial stiffness, central hemodynamics, and cardiovascular risk in hypertension

This review summarizes several scientific contributions at the recent Satellite Symposium of the European Society of Hypertension, held in Milan, Italy. Arterial stiffening and its hemodynamic consequences can be easily and reliably measured using a range of noninvasive techniques. However, like blood pressure (BP) measurements, arterial stiffness should be measured carefully under standardized patient conditions. Carotid-femoral pulse wave velocity has been proposed as the gold standard for arterial stiffness measurement and is a well recognized predictor of adverse cardiovascular outcome. Systolic BP and pulse pressure in the ascending aorta may be lower than pressures measured in the upper limb, especially in young individuals. A number of studies suggest closer correlation of end-organ damage with central BP than with peripheral BP, and central BP may provide additional prognostic information regarding cardiovascular risk. Moreover, BP-lowering drugs can have differential effects on central aortic pressures and hemodynamics compared with brachial BP. This may explain the greater beneficial effect provided by newer antihypertensive drugs beyond peripheral BP reduction. Although many methodological problems still hinder the wide clinical application of parameters of arterial stiffness, these will likely contribute to cardiovascular assessment and management in future clinical practice. Each of the abovementioned parameters reflects a different characteristic of the atherosclerotic process, involving functional and/or morphological changes in the vessel wall. Therefore, acquiring simultaneous measurements of different parameters of vascular function and structure could theoretically enhance the power to improve risk stratification. Continuous technological effort is necessary to refine our methods of investigation in order to detect early arterial abnormalities. Arterial stiffness and its consequences represent the great challenge of the twenty-first century for affluent countries, and "de-stiffening" will be the goal of the next decades.