Pulse wave velocity in elastic and muscular arteries: tracking stability and association with anthropometric and hemodynamic measurements

Cross-sectional and longitudinal evaluation of heart-to-brachium pulse wave velocity for cardiovascular disease risk

Heart-brachium pulse wave velocity (hbPWV) is a promising measure of arterial stiffness including the proximal aorta. To characterize age-associated changes and the clinical utilities of hbPWV, we evaluated the impacts of age and cardiovascular disease (CVD) risks on hbPWV cross-sectionally (N = 7868) and longitudinally (N = 3710, followed by 9.1 ± 2.0 years). hbPWV were obtained using two validated equations for arterial path length (with and without considering age-related aortic elongations). Brachial-ankle pulse wave velocity (baPWV) was used as a comparative measure. Repeated-measures correlation (rmcorr) and regression analyses were used to characterize associations of PWVs with age and Framingham's general CVD risk score (FRS). In the cross-sectional study, hbPWVs derived by both equations showed stronger correlation with age (r = 0.746 ~ 0.796) and FRS (r = 0.714-0.749) than baPWV (r = 0.554 and r = 0.643). Furthermore, hbPWVs correlated with FRS even after controlling for age (r = 0.260 ~ 0.269, P < 0.0001). In the longitudinal study, hbPWVs demonstrated significantly higher rmcorr coefficient with age than baPWV (rrm=0.439-0.511 vs. 0.307, P < 0.0001). Across the adult lifespan, age-related increases in hbPWVs were almost consistent, starting from young adults, while baPWV displayed accelerated increases with age. A receiver operating characteristic curve analysis indicated that hbPWVs depicted more robust ability to stratify general CVD risk compared with baPWV (AUC = 0.896-0.913 vs. 0.833, P < 0.0001). The results of the follow-up study were consistent with the findings of the cross-sectional investigation. Our findings suggest that hbPWV undergoes a linear augmentation with age, commencing from an early adult life stage onward, rendering it a potential marker for discerning CVD risk.

Longitudinal profiling and tracking stability in the Singapore study of macro-angiopathy and microvascular reactivity in type 2 diabetes cohort

INTRODUCTION

The Singapore Study of Macro-Angiopathy and microvascular Reactivity in Type 2 Diabetes (SMART2D) is a prospective cohort study which was started in 2011 to investigate the effect of risk factors on vascular function and diabetes-related complications in Asians. We aimed to compare the longitudinal change in risk factors by accounting for batch effect and assess the tracking stability of risk factors over time in patients recruited for SMART2D. In this study, we (1) described batch effect and its extent across a heterogenous range of longitudinal data parameters; (2) mitigated batch effect through statistical approach; and (3) assessed the tracking stability of the risk factors over time.

METHODS

A total of 2258 patients with type 2 diabetes mellitus (T2DM) were recruited at baseline. The study adopted a three-wave longitudinal design with intervals of 3 years between consecutive waves. The changes in a few selected risk factors were assessed after calibration, assuming patients with similar demographic and anthropometry profile had similar physiology. The tracking pattern of the risk factors was determined with stability coefficients derived from generalised estimating equations.

RESULTS

The medians of the longitudinal differences in risk factors between the waves were mostly modest at <10%. Larger increases in augmentation index (AI), aortic systolic blood pressure (BP) and aortic mean BP were consistently observed after calibration. The medians of the longitudinal differences in AI, aortic systolic BP and aortic mean BP between the waves were <2% before calibration, but increased slightly to <5% after calibration. Most of the risk factors had moderate to high tracking stability. Muscle mass and serum creatinine were among those with relatively high tracking stability.

CONCLUSIONS

The longitudinal differences in parameters between the waves were overall modest after calibration, suggesting that calibration may attenuate longitudinal differences inflated by non-biological factors such as systematic drift due to batch effect. Changes of the hemodynamic parameters are robust over time and not entirely attributable to age. Our study also demonstrated moderate to high tracking stability for most of the parameters.

Anthropometric measurements and their association with endothelial function and arterial stiffness of eutrophic individuals and with overweight

Objective

The objective of the study was to assess the association of anthropometric measurements with endothelial function and arterial stiffness of eutrophic individuals and with overweight.

Subjects and methods

A cross-sectional study was carried out with individuals with body mass index (BMI) between 18.5 kg/m2 and < 30 kg/m2, low to intermediate global cardiovascular risk scores, and aged ≥ 18 and < 60 years. We assessed the sociodemographic data, anthropometric variables (body weight, height, circumferences of the waist [WC], neck [NC], hip [HC], sagittal abdominal diameter [SAD], [BMI], waist-to-hip ratio [WHR], and waist-to-height ratio [WHtR]), biochemical parameters (lipid profile and nitric oxide), endothelial function (flow-mediated dilation [FMD], by ultrasound), and arterial stiffness (pulse wave velocity [PWV] and the amplification index [AIx@75] by oscillometry). Thirty-six individuals were included, 18 eutrophic and 18 with overweight, with a mean age of 37.5 ± 10.2 years, mostly at low cardiovascular risk (86.1%), female (80.6%), single (52.8%), employed with formal contracts (44.4%), and with over twelve years of education (88.9%).

Results

The PWV presented positive and moderate correlation with the WC (r = 0.584; P = 0.001), WHR (r = 0.513; P = 0.001), and WHtR (r = 0.590; P = 0.001), and positive and low correlation with the NC (r = 0.372; P = 0.013) and SAD (r = 0.356; P = 0.033). Moreover, no anthropometric parameter presented a correlation with the AIx@75 or the FMD percentage in the total sample.

Conclusion

Our findings show that in eutrophic individuals and with overweight the WC, WHR, WHtR, SAD, and NC were positively correlated with the PWV but not to the endothelial function in the overall sample. These are hypothesis-generating findings and they should be replicated in other studies.

Association between pulse wave velocity and the 10-year risk of atherosclerotic cardiovascular disease in the Chinese population: A community-based study

Accumulated evidence has shown that carotid-femoral and brachial-ankle PWV well predict cardiovascular events but it is still unclear if the predictability is same or not. In this cross-sectional study based on a community atherosclerosis cohort in Beijing, China, a total of 5282 participants without previous coronary heart disease and stroke were enrolled from a community atherosclerosis cohort in Beijing, China. The 10-year atherosclerotic cardiovascular disease (ASCVD) risk were calculated by the China-PAR model, and < 5%, 5%-10% and > 10% were defined as low, intermediate, and high risk, respectively. The average baPWV and cfPWV values were 16.63 ± 3.35 m/s and 8.45 ± 1.78 m/s, respectively. The mean 10-year ASCVD risk was 6.98% (interquartile range: 3.90%-12.01%). The patients with low, intermediate, and high 10-year ASCVD risk accounted for 34.84% (1840), 31.94% (1687),, and 33.23% (1755) respectively. Multivariate analysis showed that for every 1 m/s increase in baPWV and cfPWV, the 10-year ASCVD risk increased by 0.60% (95% confidence interval: 0.56%-0.65%, p < .001) and 1.17% (95% confidence interval: 1.09%-1.25%, p < .001), respectively. The diagnostic ability of the baPWV was comparable to the cfPWV (area under the curve: 0.870 [0.860-0.879] vs. 0.871 [0.861-0.881], p = .497). In conclusion, baPWV and cfPWV are positively associated with the 10-year risk of ASCVD in the Chinese community-based population, with a nearly identical association with a high 10-year risk of ASCVD.

The effects of glucocorticoid treatment on cardiovascular system in patients with systemic lupus erythematosus

Objectives

This study aims to assess variables concerning arterial stiffness including carotid-femoral pulse wave velocity, carotid-radial pulse wave velocity, ankle-brachial index, and the advancement of atherosclerosis development.

Patients and methods

Between October 2016 and December 2020, a total of 43 consecutive patients with systemic lupus erythematosus (SLE) (4 males, 39 females; mean age: 57±8 years; range, 42 to 65 years) were prospectively included in the study. All data were compared between the group treated with glucocorticoids and that not treated with these agents.

Results

The study group consisted of 43 patients with SLE, while 22 (51%) patients were treated with glucocorticoids. The mean duration of SLE was 12.3±5.3 years. Patients treated with glucocorticoids had lower values of ankle-brachial index compared to those who were not treated with glucocorticoids (p=0.041), although the values were within the range. A similar situation was reported for the carotid-femoral artery pulse wave velocity (p=0.032). However, carotid-radial artery pulse wave velocity was not significantly different between both groups (p=0.12).

Conclusion

Properly selected therapy is important in the prevention of CVD.

Large-Scale Multi-Omics Studies Provide New Insights into Blood Pressure Regulation

Recent genome-wide association studies uncovered part of blood pressure’s heritability. However, there is still a vast gap between genetics and biology that needs to be bridged. Here, we followed up blood pressure genome-wide summary statistics of over 750,000 individuals, leveraging comprehensive epigenomic and transcriptomic data from blood with a follow-up in cardiovascular tissues to prioritise likely causal genes and underlying blood pressure mechanisms. We first prioritised genes based on coding consequences, multilayer molecular associations, blood pressure-associated expression levels, and coregulation evidence. Next, we followed up the prioritised genes in multilayer studies of genomics, epigenomics, and transcriptomics, functional enrichment, and their potential suitability as drug targets. Our analyses yielded 1880 likely causal genes for blood pressure, tens of which are targets of the available licensed drugs. We identified 34 novel genes for blood pressure, supported by more than one source of biological evidence. Twenty-eight (82%) of these new genes were successfully replicated by transcriptome-wide association analyses in a large independent cohort (n = ~220,000). We also found a substantial mediating role for epigenetic regulation of the prioritised genes. Our results provide new insights into genetic regulation of blood pressure in terms of likely causal genes and involved biological pathways offering opportunities for future translation into clinical practice.

RNO3 QTL Regulates Vascular Structure and Arterial Stiffness in the Spontaneously Hypertensive Rat

Increased arterial stiffness is an independent risk factor for hypertension, stroke, and cardiovascular morbidity. Thus, understanding the factors contributing to vascular stiffness is of critical importance. Here, we used a rat model containing a known quantitative trait locus (QTL) on chromosome 3 (RNO3) for vasoreactivity to assess potential genetic elements contributing to blood pressure, arterial stiffness, and their downstream effects on cardiac structure and function. Although no differences were found in blood pressure at any time point between parental spontaneously hypertensive rats (SHRs) and congenic SHR.BN3 rats, the SHRs showed a significant increase in arterial stiffness measured by pulse wave velocity. The degree of arterial stiffness increased with age in the SHRs and was associated with compensatory cardiac changes at 16 wk of age, and decompensatory changes at 32 wk, with no change in cardiac structure or function in the SHR.BN3 hearts at these time points. To evaluate the arterial wall structure, we used multiphoton microscopy to quantify cells and collagen content within the adventitia and media of SHR and SHR.BN3 arteries. No difference in cell numbers or proliferation rates was found, although phenotypic diversity was characterized in vascular smooth muscle cells. Herein, significant anatomical and physiological differences related to arterial structure and cardiovascular tone including collagen, pulse wave velocity (PWV), left ventricular (LV) geometry and function, and vascular smooth muscle cell (VSMC) contractile apparatus proteins were associated with the RNO3 QTL, thus providing a novel platform for studying arterial stiffness. Future studies delimiting the RNO3 QTL could aid in identifying genetic elements responsible for arterial structure and function.

Arterial stiffness is associated with oxidative stress and endothelial activation among persons with treated HIV in Zambia

BACKGROUND

Cardiovascular disease (CVD) prevalence is rising among persons with HIV (PLWH) in sub-Saharan Africa. Oxidative stress and endothelial activation, resulting in reduced vascular compliance, are contributors to CVD risk. However, there is a paucity of vascular health data in this population.

OBJECTIVES

To assess the relationships of oxidative stress and endothelial activation with vascular stiffness among PLWH.

METHOD

Fifty-four PLWH on antiretroviral therapy > 5 years and 57 HIV-negative controls, all aged 18-45 years, were enrolled from the University Teaching Hospital, Lusaka, Zambia. Oxidative stress was measured by nitrotyrosine, a peroxynitrite biomarker, and endothelial activation by soluble intercellular adhesion molecule-1 (sICAM-1) plasma levels. Vascular compliance was measured using carotid-radial pulse wave velocity (crPWV) and arterial stiffness index (crASI).

RESULTS

PLWH had higher sICAM-1 levels (median 345 ng/mL) compared to controls (275 ng/mL, p < 0.01), as well as higher nitrotyrosine levels (297 versus 182 nM; p = 0.02). Median crPWV was similar between the groups, but PLWH had higher crASI (2.4 versus 2.2 cm/ms; p < 0.05). After adjusting for age, fat mass, and blood pressure, the estimated effect of a one unit increase in nitrotyrosine on crPWV were twofold higher in the PLWH, but neither reached significance. In a model pooling all participants, there were significant differences in the relationship of nitrotyrosine with crPWV and crASI by HIV status.

CONCLUSION

PLWH in sub-Saharan Africa had significantly greater oxidative stress and endothelial activation compared to HIV-negative individuals. These factors may contribute to increased arterial stiffness and higher CVD prevalence in this population.

The impact of heart rate on pulse wave velocity: an in-silico evaluation

BACKGROUND

Clinical and experimental evidence regarding the influence of heart rate (HR) on arterial stiffness and its surrogate marker carotid-to-femoral pulse wave velocity (cf-PWV) is conflicting. We aimed to evaluate the effect of HR on cf-PWV measurement under controlled haemodynamic conditions and especially with respect to blood pressure (BP) that is a strong determinant of arterial stiffness.

METHOD

Fifty-nine simulated cases were created using a previously validated in-silico model. For each case, cf-PWV was measured at five HR values, 60, 70, 80, 90, 100 bpm. With increasing HR, we assessed cf-PWV under two scenarios: with BP free to vary in response to HR increase, and with aortic DBP (aoDBP) fixed to its baseline value at 60 bpm, by modifying total peripheral resistance accordingly. Further, we quantified the importance of arterial compliance (C) on cf-PWV changes caused by increasing HR.

RESULTS

When BP was left free to vary with HR, a significant HR-effect on cf-PWV (0.66 ± 0.24 m/s per 10 bpm, P < 0.001) was observed. This effect was reduced to 0.21 ± 0.14 m/s per 10 bpm (P = 0.048) when aoDBP was maintained fixed with increasing HR. The HR-effect on the BP-corrected cf-PWV was higher in the case of low C = 0.8 ± 0.3 ml/mmHg (0.26 ± 0.15 m/s per 10 bpm, P = 0.014) than the case of higher C = 1.7 ± 0.5 ml/mmHg (0.16 ± 0.07 m/s per 10 bpm, P = 0.045).

CONCLUSION

Our findings demonstrated that relatively small HR changes may only slightly affect the cf-PWV. Nevertheless, in cases wherein HR might vary at a greater extent, a more clinically significant impact on cf-PWV should be considered.

Decreased heritability and emergence of novel genetic effects on pulse wave velocity from youth to young adulthood

Increased arterial stiffness measured by pulse wave velocity (PWV) is an important parameter in the assessment of cardiovascular risk. Our previous longitudinal study has demonstrated that carotid-distal PWV showed reasonable stability throughout youth and young adulthood. This stability might be driven by genetic factors that are expressed consistently over time. We aimed to illustrate the relative contributions of genetic and environmental factors to the stability of carotid-distal PWV from youth to young adulthood. We also examined potential ethnic differences. For this purpose, carotid-distal PWV was measured twice in 497 European American (EA) and African American (AA) twins, with an average interval time of 3 years. Twin modelling on PWV showed that heritability decreased over time (62–35%), with the nonshared environmental influences becoming larger. There was no correlation between the nonshared environmental factors on PWV measured at visit 1 and visit 2, with the phenotypic tracking correlation (r = 0.32) completely explained by shared genetic factors over time. Novel genetic influences were identified accounting for a significant part of the variance (19%) at the second measurement occasion. There was no evidence for ethnic differences. In summary, novel genetic effects appear during development into young adulthood and account for a considerable part of the variation in PWV. Environmental influences become larger with age for PWV.

Validation of a wearable cuff-less wristwatch-type blood pressure monitoring device

Ambulatory blood pressure (BP) monitoring is recommended to improve the management of hypertension. Here, we investigated the accuracy of BP estimated using a wearable cuff-less device, InBodyWATCH, compared with BP measured using a manual sphygmomanometer. Thirty-five adults were enrolled (age 57.1 ± 17.9 years). The BP was estimated using InBodyWATCH with an individualized estimation based on a neural network model. Three paired sets of BPs from the two devices were compared using correlation analysis and Bland–Altman plots (n = 105 paired BP readings). The correlations for both systolic and diastolic BP (SBP and DBP) between the two devices were high (r = 0.964 and 0.939, both P < 0.001). The mean difference was 2.2 ± 6.1 mmHg for SBP and −0.2 ± 4.2 mmHg for DBP; these were not significant (P = 0.472 for SBP and P = 0.880 for DBP). The proportions of estimated SBP/DBP obtained from the InBodyWATCH within ± 5 mmHg of manual SBP/DBP were 71.4%/83.8%; within ± 10 mmHg they were 86.7%/98.1%; and within ± 15 mmHg they were 97.1%/99.0%. The estimated BP from this wearable cuff-less device correlated highly with the manual BP and showed good accuracy, suggesting its potential to be used in ambulatory BP monitoring.

Exercise effects on arterial stiffness and heart health in children with excess weight: The SMART RCT

INTRODUCTION

Childhood obesity and inactivity are associated with cardiovascular risk. Evidence is limited for exercise effects on arterial health in children.

METHODS

One hundred and seventy-five inactive children with overweight or obesity (8-11 years, ≥85th percentile BMI, 61% female, 87% Black, 73% with obesity) were randomized to an 8-month daily after-school aerobic exercise program (40 min/day, n = 90) or a sedentary control condition (n = 85). Carotid-femoral pulse wave velocity (PWV, primary outcome, arterial stiffness), fitness, adiposity, blood pressure (BP), glucose, insulin resistance, lipids, and C-reactive protein were measured at baseline and posttest (8 months). Adiposity, fitness, and BP were measured again at follow-up, 8-12 months later. Intent-to-treat analyses were conducted using mixed models.

RESULTS

The study had 89% retention, with attendance of 59% in exercise and 64% in the control condition, and vigorous exercise participation (average heart rate 161 ± 7 beats/min). Compared with controls, the exercise group had twice the improvement in fitness (VȮ2 peak, 2.7 (95% CI 1.8, 3.6) vs. 1.3 (0.4, 2.3) mL/kg/min) and adiposity (-1.8 (-2.4, -1.1) vs. -0.8 (-1.5, -0.1)%), each p = 0.04, and a large improvement in HDL-cholesterol (0.13 (0.075, 0.186) vs. -0.028 (-0.083, 0.023) mmol/L, p < 0.0001). There was no group × time effect on other outcomes at 8 months, or on any outcomes at follow-up. The change in PWV at 8 months correlated with changes in insulin and insulin resistance (both r = 0.32), diastolic BP (r = 0.24), BMI (r = 0.22), and adiposity (r = 0.18).

CONCLUSIONS

Eight months of aerobic exercise training improved fitness, adiposity, and HDL-cholesterol levels, but did not reduce arterial stiffness in children with excess weight. PWV improved as a function of insulin resistance, BP, BMI, and adiposity. Weight loss may be required to improve arterial stiffness. Exercise benefits waned after discontinuing the program.

Association of brachial-cuff excess pressure with carotid intima-media thickness in Australian adults: a cross-sectional study

OBJECTIVE

Reservoir pressure parameters [e.g. reservoir pressure (RP) and excess pressure (XSP)] measured using tonometry predict cardiovascular events beyond conventional risk factors. However, the operator dependency of tonometry impedes widespread use. An operator-independent cuff-based device can reasonably estimate the intra-aortic RP and XSP from brachial volumetric waveforms, but whether these estimates are clinically relevant to preclinical phenotypes of cardiovascular risk has not been investigated.

METHODS

The RP and XSP were derived from brachial volumetric waveforms measured using cuff oscillometry (SphygmoCor XCEL) in 1691 mid-life adults from the CheckPoint study (a population-based cross-sectional study nested in the Longitudinal Study of Australian Children). Carotid intima--media thickness (carotid IMT, n = 1447) and carotid--femoral pulse wave velocity (PWV, n = 1632) were measured as preclinical phenotypes of cardiovascular risk. Confounders were conventional risk factors that were correlated with both exposures and outcomes or considered as physiologically important.

RESULTS

There was a modest association between XSP and carotid IMT (β = 0.76 μm, 95% CI, 0.25-1.26 partial R = 0.8%) after adjusting for age, sex, BMI, heart rate, smoking, diabetes, high-density lipoprotein cholesterol and mean arterial pressure. Neither RP nor XSP were associated with PWV in the similarly adjusted models (β = -0.47 cm/s, 95% CI, -1.15 to 0.20, partial R = 0.2% for RP, and β = 0.04 cm/s, 95% CI, -0.59 to 0.67, partial R = 0.01% for XSP).

CONCLUSION

Cuff-based XSP associates with carotid IMT independent of conventional risk factors, including traditional BP, but the association was weak, indicating that further investigation is warranted to understand the clinical significance of reservoir pressure parameters.

Association of pulse wave velocity and intima-media thickness with cardiovascular risk factors in young adults

Pulse wave velocity (PWV), a measure of arterial stiffness, and intima‐media thickening (IMT), a measure of early atherosclerosis, are intermediate markers of cardiovascular disease which are predictive of cardiovascular events. Traditionally, both were thought to result from accumulative exposure to traditional cardiovascular risk factors. However, their association with risk factors in young adults in low‐income settings is unknown. We sought to investigate the association between PWV and IMT with traditional cardiovascular risk factors in the Andhra Pradesh Children and Parents Study cohort from Southern India. Male and female adults (N = 1440) aged between 20 and 24 years underwent measures of PWV and IMT. Exposure variables included smoking, body mass index (BMI), mean arterial pressure (MAP), glucose, homeostatic model assessment of insulin resistance (HOMA‐IR), total cholesterol, high‐density lipoprotein cholesterol (HDL‐cholesterol), and triglycerides. Association between outcome and exposure variables was assessed using linear regression analysis. Average values for PWV and IMT were 5.9 ± 0.6 m/s and 0.5 ± 0.1 mm. In univariable analysis, PWV associated with MAP, BMI, smoking, total cholesterol, glucose, and HOMA‐IR and IMT associated with MAP, BMI, tobacco use, and HDL‐cholesterol. In multivariable analysis, PWV remained strongly positively associated with MAP increasing by 0.5 m/s (P < .001) for a 10 mm Hg increase in MAP (R² = .37). In contrast, IMT negatively associated with HDL‐cholesterol (β = −.10; P = .012, R² = .02). There was weak evidence that PWV and IMT positively associated with BMI. In young adults from Southern India, PWV positively associated with blood pressure and IMT negatively associated with HDL‐cholesterol. This suggests separate etiologies for atherosclerosis and arterial stiffening in young adults.

Biodegrading highly porous elastomeric graft regenerates muscular and innervated carotid artery-Comparative study with vein graft

This study aims to investigate the superiorities of fast degrading elastomeric poly(glycerol sebacate) (PGS)/polycaprolactone (PCL) grafts over autologous vein grafts in the reconstruction of carotid artery, thus providing more suitable vascular grafts for carotid artery replacement. We fabricated small arterial grafts from microporous tubes of PGS reinforced with PCL nanofibers on the outer surface. As control, autologous jugular veins were harvested as vein grafts. Both types of grafts were interpositioned in rat carotid arteries and evaluated at 1 year postoperatively. PGS/PCL grafts remodelled into "neoarteries" (regenerated arteries) with smooth and even vessel wall approximate to native carotid arteries. In contrast, dilated vessel cavity and thickening vessel wall presented in neoarteries remoulded from vein. Histologically, neoarteries from both groups mimic arterial tissue architecture with a confluent endothelium and media and adventita-like layers, whereas PGS/PCL neoarteries presented well-organized muscular component and elastic fibres, which contributed more flexibility and elasticity. Different from vein grafts, PGS/PCL neoarteries acquired reinnervation and displayed apparent vascular function of contraction and relaxation, as was confirmed with responsiveness to various vasoactivators, which suggests that vascular cells within neoarteries express functional phenotypes and potential of autonomic reactivity that carotid arteries owned. To conclude, according to the requirement of strong flexibility, innervation from sympathetic and parasympathetic nerves which can response the carbon dioxide and blood pressure, the muscular remodelling and innervation possessed promising possibility of clinical application.

Determinants of pulse wave velocity trajectories from youth to young adulthood: the Georgia Stress and Heart Study

OBJECTIVE

Increased arterial stiffness measured by pulse wave velocity (PWV) has been shown to be an important parameter of cardiovascular risk. Longitudinal development of PWV from youth to early adulthood and its possible sociodemographic, anthropometric, hemodynamic and behavioral moderators will be illustrated.

METHODS

Individual growth curves of carotid-distal PWV across age were created for 559 African American and European American men and women with a maximum of five assessments over an average of 7-year follow-up (mean age at participants' first assessment, 22.3 ± 3.4).

RESULTS

African Americans and men had significantly higher PWV than did European Americans and women (Ps < 0.01), respectively. A three-way interaction (P < 0.001) between age, sex and ethnicity was observed with African American men displaying a larger rate of increase in PWV with age than the other three ethnic and sex groups. The ethnicity and sex effects on PWV persisted when controlling for other moderators. Waist circumference was the strongest anthropometric predictor but its effect on PWV was only significant in women. Mean arterial pressure was the strongest hemodynamic predictor, marital status of parents was the strongest socioeconomic predictor and marijuana use was the strongest behavioral predictor of PWV. The best-fitting full model explained in total 59.4% of the between-subject variance in PWV with ethnicity, sex and age explaining 25.6%.

CONCLUSION

We observed significant ethnic and sex differences in longitudinal trajectories of PWV in youth and young adults. In addition, individual differences in PWV growth can largely be explained by mean arterial pressure, waist, marital status of parents and marijuana use.

Genetic and environmental determinants of longitudinal stability of arterial stiffness and wave reflection: a twin study

BACKGROUND

We aimed at evaluating the impact of genetic and environmental factors on longitudinal changes in aortic pulse wave velocity (aPWV) and aortic augmentation index (aAIx).

METHOD

Three hundred and sixty-eight Italian and Hungarian adult twins (214 monozygotic, 154 dizygotic) underwent repeated evaluations of aPWV and aAIx (TensioMed Arteriograph). Within-individual/cross-wave, cross-twin/within-wave and cross-twin/cross-wave correlations were calculated; bivariate Cholesky models were fitted to calculate additive genetic (A), shared environmental (C) and unique environmental (E) components.

RESULTS

For both aPWV and aAIx, cross-twin correlations in monozygotic pairs (r between 0.35 and 0.56) were all significant and always higher than in dizygotic pairs, both at wave 1 and at wave 2. Heritability and unshared environmental proportion of variance at each wave were substantially time-invariant for aPWV (heritability 0.51, 95% CI 0.36-0.63 at wave 1; 0.49, 95% CI 0.34-0.62 at wave 2), whereas for aAIx, we observed a diminished genetic effect (heritability 0.57, 95% CI 0.45-0.67 at wave 1; 0.37, 95% CI 0.21-0.51 at wave 2). Overlapping genetic factors explained a high proportion (0.88, 95% CI 0.61-1.00) of longitudinal covariance for aPWV, and had a relatively lower impact on aAIx (0.55, 95% CI 0.35-0.70). Genetic correlations of aPWV (r = 0.64, 95% CI 0.42-0.85) and aAIx (r = 0.70, 95% CI 0.52-0.87) between waves were lower than 1, suggesting a potential contribution of novel genetic variance on arterial stiffening.

CONCLUSION

Changes in aPWV and aAIx over time are largely genetically determined. Our results might stimulate further studies on genetic and epigenetic factors influencing the process of vascular ageing.

Arterial path length estimation for heart-to-brachium pulse wave velocity

As an initial step to better define heart-brachial pulse wave velocity (hbPWV), a novel measure of proximal aortic stiffness, we proposed and validated a simple formula to estimate the arterial path length (Lhb) for hbPWV. In 190 patients aged 19-79 years, the reference Lhb was measured by a three-dimensional MRI. Using multiple regression analysis and fivefold cross-validation, estimation formulae were created using age, sex, and height. hbPWV was calculated as Lhb divided by the time interval from the second heart sound to the dicrotic notch on the brachial pressure wave. In a comparison of hbPWV calculated from MRI-based Lhb, strong correlations and accuracy were observed for the hbPWV obtained from the estimated Lhb by sex and height (r = 0.969, -0.05 ± 0.54 m per s of the mean difference), and even greater correlations and accuracy were observed for the estimated value by age, sex, and height (r = 0.976, 0.00 ± 0.43 m per s of the mean difference). hbPWV values obtained from the straight distance method and the height-based equation showed significant biases with mean differences of 2.64 ± 0.94 and 2.53 ± 0.94 m per s. hbPWV could be evaluated accurately by the simple equation to estimate Lhb.

A Magnetic Plethysmograph Probe for Local Pulse Wave Velocity Measurement

OBJECTIVE

We present the design and experimental validation of an arterial compliance probe with dual magnetic plethysmograph (MPG) transducers for local pulse wave velocity (PWV) measurement. The MPG transducers (positioned at 23 mm distance apart) utilizes Hall-effect sensors and permanent magnets for arterial blood pulse detection.

METHODS

The MPG probe was initially validated on an arterial flow phantom using a reference method. Further, 20 normotensive subjects (14 males, age = 24 ± 3.5 years) were studied under two different physical conditions: 1) Physically relaxed condition, 2) Postexercise condition. Local PWV was measured from the left carotid artery using the MPG probe. Brachial blood pressure (BP) was measured to investigate the correlation of BP with local PWV.

RESULTS

The proposed MPG arterial compliance probe was capable of detecting high-fidelity blood pulse waveforms. Reliable local pulse transit time estimates were assessed by the developed measurement system. Beat-by-beat local PWV was measured from multiple subjects under different physical conditions. A profound increment was observed in the carotid local PWV for all subjects after exercise (average increment = 0.42 ± 0.22 m/s). Local PWV values and brachial BP parameters were significantly correlated (r ≥ 0.72), except for pulse pressure (r = 0.42).

CONCLUSION

MPG arterial compliance probe for local PWV measurement was validated. Carotid local PWV measurement, its variations due to physical exercise and correlation with BP levels were examined during the in vivo study.

SIGNIFICANCE

A novel dual MPG probe for local PWV measurement and potential use in cuffless BP measurement.

Markers of arterial stiffness in a sample of Lebanese subjects with Grade I essential hypertension

Objectives:

Arterial stiffness is becoming a major global condition associated with an increased risk of cardiovascular problems and death. Several markers have been linked to arterial stiffness.

Methods:

To determine and evaluate these relations, anthropometric parameters (weight, height, and pulse rate), biochemical profile, and central and peripheral indices of arterial function were measured in 114 Lebanese subjects with Grade I essential hypertension.

Results:

Age was associated with a higher pulse wave velocity (p = .001), central systolic blood pressure (p = .013), central pulse pressure (p = .028), central augmentation index (p ≤ .0001) with a lower heart rate (p = .08), and glomerular filtration rate (p = .019). Pulse wave velocity was found to be higher in older subjects (>65 years) and correlated with higher body mass index (r = .85) independent of age. Aging also correlated with higher plasma glucose and alterations in calcium–phosphorus metabolism.

Conclusion:

Aging is associated with increased arterial stiffness which is reflected by an increase in the pulse wave velocity, augmentation index, central pulse pressure, and central systolic blood pressure with a reduction in heart rate. Also, a higher body mass index and a lower estimated glomerular filtration rate (< 60 mL/min/1.73 m²) are associated with increased arterial stiffness while calcium and phosphorus metabolism may play a role by promoting vascular calcification.

Ejection time: influence of hemodynamics and site of measurement in the arterial tree

The left ventricular ejection time is routinely measured from a peripheral arterial waveform. However, the arterial waveform undergoes constant transformation as the pulse wave propagates along the arterial tree. Our goal was to determine if the left ventricular ejection time measured peripherally in the arterial tree accurately reflected the ejection time measured through the aortic valve. Moreover, we examined/accessed the modulating influence of hemodynamics on ejection time measurements. Continuous wave Doppler waveform images through the aortic valve and the simultaneously obtained radial artery pressure waveforms were analyzed to determine central and peripheral ejection times, respectively. The peripheral ejection time was significantly longer than the simultaneously measured central ejection time (174.5±25.2 ms vs. 120.7±14.4 ms; P<0.0001; 17.4±8.7% increase). Moreover, the ejection time prolongation was accentuated at lower blood pressures, lower heart rate and lower pulse wave velocity. The time difference between centrally and peripherally measured ejection times likely reflects intrinsic vascular characteristics. Moreover, given that the ejection time also depends on blood pressure, heart rate and pulse wave velocity, peripherally measured ejection times might need to be adjusted to account for changes in these variables.