Arterial pulse wave velocity and risk factors for peripheral vascular disease

Influences on the Functional Behavior of Great Arteries during Orthostasis

Background

Arterial compliance reduction has been associated with aging and hypertension in supine position. However, the dynamic effects of orthostatism on aortic distensibility has not been defined.

Objective

We sought to determine the orthostatic influence and the interference of age, blood pressure (BP) and heart rate (HR) on the great arteries during gravitational stress.

Methods

Ninety-three healthy volunteers (age 42 ± 16 years). Carotid-femoral pulse wave velocity (PWV) assumed as aortic stiffness was assessed in supine position (basal phase), during tilt test (TT) (orthostatic phase) and after return to supine position (recovery phase). Simultaneously with PWV acquisition, measures of BP and HR rate were recorded.

Results

PWV during TT increased significantly compared to the basal and recovery phases (11.7 ± 2.5 m/s vs. 10.1 ± 2.3 m/s and 9.5 ± 2.0 m/s). Systolic BP (r = 0.55, r = 0.46 and r = 0.39) and age (r = 0.59, r = 0.63 and r = 0.39) correlated with PWV in all phases. The significance level for all tests was established as α = 0.05.

Conclusion

We conclude that there is a permanent increase in PWV during orthostatic position that was returned to basal level at the recovery phase. This dynamic pattern of PWV response, during postural changes, can be explained by an increase in hydrostatic pressure at the level of abdominal aorta which with smaller radius and an increased elastic modulus, propagates the pulse in a faster way. Considering that it could increase central pulse reflection during the orthostatic position, we speculate that this mechanism may play a role in the overall adaptation of humans to gravitational stress.

Do Novel Risk Biomarkers Reflect the Severity of Peripheral Arterial Disease?

The association between novel atherosclerotic risk biomarkers and severity of peripheral arterial disease (PAD) was assessed. Patients (n = 133) with PAD were recruited. Established risk biomarkers including low- and high-density cholesterol, triglycerides, and blood pressure were measured. Novel risk biomarkers including plasma C-reactive protein, von Willebrand factor (vWF), interleukin 6, red cell folate (RCF), vitamin B12, total homocysteine (tHcy), and Hcy genotypes were also determined. The severity of PAD was evaluated, using ankle—brachial pressure index (ABPI), brachial—knee, and brachial—ankle pulse wave velocity (bk- and ba-PWV). Plasma tHcy and systolic blood pressure had a positive independent correlation with bk-PWV (β = +0.56, P = .02 and β = +0.38, P < .001, respectively). Red cell folate had an independent inverse correlation with bk-PWV (β = —0.01, P = .01). Systolic blood pressure showed an independent positive correlation with ba-PWV only after adjustment for other risk biomarkers (β = +0.1, P = .04). Novel markers, plasma tHcy, and RCF levels correlated with the severity of PAD.

Nonenhanced MR angiography

While nonenhanced magnetic resonance (MR) angiographic methods have been available since the earliest days of MR imaging, prolonged acquisition times and image artifacts have generally limited their use in favor of gadolinium-enhanced MR angiographic techniques. However, the combination of recent technical advances and new concerns about the safety of gadolinium-based contrast agents has spurred a resurgence of interest in methods that do not require exogenous contrast material. After a review of basic considerations in vascular imaging, the established methods for nonenhanced MR angiographic techniques, such as time of flight and phase contrast, are considered and their advantages and disadvantages are discussed. This article then focuses on new techniques that are becoming commercially available, such as electrocardiographically gated partial-Fourier fast spin-echo methods and balanced steady-state free precession imaging both with and without arterial spin labeling. Challenges facing these methods and possible solutions are considered. Since different imaging techniques rely on different mechanisms of image contrast, recommendations are offered for which strategies may work best for specific angiographic applications. Developments on the horizon include techniques that provide time-resolved imaging for assessment of flow dynamics by using nonenhanced approaches.

Metabolic syndrome and its components in relation to brachial-ankle pulse wave velocity in middle-aged Taiwanese males

To evaluate the association of The study is to evaluate the association of metabolic syndrome (MS) and its components on brachial-ankle pulse wave velocity (baPWV), an indirect marker of subclinical atherosclerosis, in middle-aged Taiwanese males. A total of 442 men aged 40 to 65 years were included in this cross-sectional survey. Arterial stiffness was measured using a non-invasive method by baPWV. MS is defined by the presence of ≥ 3 components using the modified National Cholesterol Education Program criteria. The mean baPWV was 1478.6 and 1520.3 cm/sec in normal-weight and overweight adults, respectively. Age, systolic blood pressure (BP), diastolic BP, and fasting blood glucose (FBG) correlated with baPWV levels in normal-weight and overweight males. In multiple logistic regression analysis, after adjusting for potential confounders, MS and its components (such as high BP and high FBG) were significantly associated with abnormal baPWV (≥1400 cm/sec) (p < 0.001). MS and its components are significantly associated with abnormal baPWV in Taiwanese middle-aged males and in addition, high BP was the component of MS most significantly associated with abnormal baPWV.

Haemodynamic determinants of elevated pulse wave velocity during acute isometric handgrip exercise

BACKGROUND

Measurement of pulse wave velocity (PWV) provides a reliable index of vascular stiffness. Despite its widespread application, the physiological interrelationships between PWV, blood pressure (BP) and in particular, heart rate (HR), have yet to be fully elucidated. Furthermore, little is known about altered arterial compliance during acute exercise.

AIM

To examine the effects of 3-min supine non-dominant isometric handgrip exercise (ISOMEX), performed at 30% of maximum voluntary contraction, on carotid-radial PWV, BP and HR in the dominant arm of 51 healthy subjects.

RESULTS

During exercise, PWV correlated strongly with diastolic BP (r = 0.55, p < 0.01) and mean arterial pressure (r = 0.51, p < 0.01). PWV and HR failed to correlate at rest or during exercise.

CONCLUSION

ISOMEX invoked an elevated PWV, which is predominantly related to BP or factors determining it, and not HR. The carotid-radial PWV stress test is a simple measurement that may have prognostic potential for use in large-scale population studies.

A short-term admission improved brachial-ankle pulse wave velocity in type 2 diabetic patients

Brachial-ankle pulse wave velocity (baPWV) is a non-invasive method for assessing arterial stiffness associated with atherosclerosis. We examined whether baPWV could improve during a 2-week hospital-based education program in patients with type 2 diabetes and whether improvement associates with changes in known atherogenic risk factors. Body mass index (BMI), blood pressure (BP), fasting plasma glucose (FPG), insulin, lipid profiles and baPWV were measured in 32 type 2 diabetic patients before and after an educational program that included advice about nutrition and exercise. Relationship between the changes in baPWV and additional parameters, 24h-urinary excretion of C-peptide, visceral and subcutaneous fat area by abdominal computer tomography and intima-medial thickness (IMT) of the carotid artery by ultrasonography, were also evaluated. Baseline values of baPWV significantly correlated with age, duration of diabetes, BP, IMT and FPG. BaPWV significantly decreased after the program (-120+/-108.4 cm/s, P<0.0001) and this change significantly correlated with that of systolic BP (r=0.697, P<0.0001) and FPG (r=0.452, P<0.05). These results indicate that short-term hospitalization with an educational program can improve arterial wall stiffness, perhaps due to improvements in BP and glycemic control.

Human cortical perfusion and the arterial pulse: a near-infrared spectroscopy study

BACKGROUND

The pulsatile nature of the arterial pulse induces a pulsatile perfusion pattern which can be observed in human cerebral cortex with non-invasive near-infrared spectroscopy. The present study attempts to establish a quantitative relation between these two events, even in situations of very weak signal-to-noise ratio in the cortical perfusion signal. The arterial pulse pattern was extracted from the left middle finger by means of plethesmographic techniques. Changes in cortical perfusion were detected with a continuous-wave reflectance spectrophotometer on the scalp overlying the left prefrontal cortex. Cross-correlation analysis was performed to provide evidence for a causal relation between the arterial pulse and relative changes in cortical total hemoglobin. In addition, the determination of the statistical significance of this relation was established by the use of phase-randomized surrogates.

RESULTS

The results showed statistically significant cross correlation between the arterial and perfusion signals.

CONCLUSIONS

The approach designed in the present study can be utilized for a quantitative and continuous assessment of the perfusion states of the cerebral cortex in experimental and clinical settings even in situations of extremely low signal-to-noise ratio.

Clustered features of the metabolic syndrome and the risk for increased aortic pulse wave velocity in middle-aged Japanese men

The association between different features of the metabolic syndrome (MS) (obesity, hypertension, hypercholesterolemia, low high-density lipoprotein cholesterol level, hypertriglyceridemia, high fasting plasma glucose level, and hyperuricemia) and the risk for increased aortic pulse wave velocity (PWV) of > or = 8.0 m/sec was examined in 2431 Japanese men aged 35 to 54 years who were not taking antihypertensive medication. After controlling for age, cigarette smoking, and alcohol intake, the odds ratios for increased aortic PWV in subjects with 1, 2, 3, and > or = 4 features of the MS, compared with those without features of the MS, were 1.35 (95% CI, 0.86 to 2.11), 1.90 (95% CI, 1.18 to 3.06), 1.57 (95% CI, 0.89 to 2.76), and 2.38 (95% CI, 1.26 to 4.49), respectively (p for trend = 0.003). A 9-year longitudinal study was also performed to prospectively examine the association between clustered features of the MS and the development of increased aortic PWV in 2073 men without aortic stiffness with a PWV < 8.0 m/sec and without antihypertensive medication during the follow-up period. The multivariate-adjusted hazard ratios for the incidence of increased aortic PWV in subjects with 1, 2, 3, and > or = 4 features of the MS, compared with those without features of the MS, were 1.39 (95% CI, 1.10 to 1.77), 1.46 (95% CI, 1.1 1 to 1.92), 1.75 (95% CI, 1.27 to 2.40), and 2.22 (95% CI, 1.52 to 3.25), respectively (p for trend < 0.001). These results suggest that clustered features of the MS are closely associated with the risk for increased aortic PWV in middle-aged Japanese men.

Diastolic blood pressure is an important determinant of augmentation index and pulse wave velocity in young, healthy males

Pulse wave velocity (PWV) and augmentation index are widely used measures of arterial stiffness. The purpose of this study was to evaluate the role of blood pressure as a determinant of both indices independent of potentially confounding factors including gender, age and cardiovascular disorders. A total of 77 young, healthy subjects were investigated under resting conditions. Augmentation index was derived by pulse wave analysis using carotid applanation tonometry. PWV was determined from pressure tracing over the carotid and femoral artery. The relations between stiffness markers and haemodynamic parameters were analysed by simple (r) and multiple (beta) regression analysis. Using simple regression analysis, augmentation index was correlated to age (r=0.292, P=0.0105), diastolic blood pressure (DBP, r=0.483, P<0.0001), mean arterial blood pressure (MAP, r=0.381, P=0.0007), pulse pressure (r=-0.414, P=0.0002) and total peripheral resistance (r=0.266, P=0.0204). After multiple regression analysis, augmentation index remained significantly correlated only to DBP (beta=0.347, P=0.0051). Using simple regression analysis, PWV was correlated to age (r=0.304, P=0.0067), systolic blood pressure (r=0.280, P=0.0129). DBP (r=0.455, P<0.0001), MAP (r=0.446, P&<0.0001) and heart rate (r=0.348, P=0.0018). After multiple regression analysis, PWV remained correlated only to age (beta=0.218, P=0.0422) and DBP (beta=0.4105, P=0.0316). In summary, DBP is an important determinant of augmentation index and PWV in young, healthy males. Further studies are needed to characterize the impact of blood pressure on arterial stiffness in other populations including females and older subjects.

Spontaneous baroreflex sensitivity: toward an ideal index of cardiovascular risk in hypertension?

OBJECTIVE

Estimating the risk entailed by classical risk factors like blood pressure (BP) or serum cholesterol may be difficult because of their variability and the often unknown duration of exposure. Having variables integrating the impact of those classical risk factors on the cardiovascular system would probably aid the prediction of cardiovascular events. The present study aimed at determining whether cardiac baroreflex sensitivity (BRS), correlates with several risk factors and thus is a good candidate for being such an integrative variable. As a comparison, left ventricular mass (LVM), pulse wave velocity (PWV), and creatinine were also tested for association with risk factors.

DESIGN

A total of 302 subjects referred for hypertension, were considered. They had a 24-h BP recording and a determination of BRS by two different methods (sequence and alpha coefficient), in two different positions (lying and standing). They were also tested for the presence of left ventricular hypertrophy (LVH) (by echocardiography and electrocardiogram) and had a PWV measurement. Biological testing included serum lipids, blood glucose, creatinine, proteinuria and urinary excretion of microalbumin.

RESULTS

There was a strong correlation between the two methods of BRS measurement in each position (P < 0.001). BRS determined by the sequence method in the lying position was correlated significantly and independently with age, 24-h systolic BP, heart rate, and serum cholesterol with P values < 0.001, < 0.001, < 0.01, and < 0.05, respectively. In an univariate analysis, BRS was also correlated with echocardiographic LVM index (r = -0.21, P < 0.05) and PWV (r = -0.27, P < 0.001), which possibly reflects its dependence on both vascular and cardiac damages.

CONCLUSION

The present study supports the hypothesis that BRS could encompass the impact over time of several risk factors on the cardiovascular system. Thus, it may constitute a valuable parameter in assessing more precisely the risk of cardiovascular events.

Clinical usefulness of measuring pulse wave velocity in predicting cerebrovascular disease: evaluation from a cross-Sectional and longitudinal follow-up study

The present study was designed both as a cross-sectional and longitudinal follow-up study to evaluate the association between pulse wave velocity (PWV) and cardiovascular disease. The subjects in this study included a total 260 patients (134 men and 126 women) ranging from 25 to 91 years (mean, 67.6+/-11.0 years). Carotid to femoral PWV was measured in all patients. The subsequent development of a cerebrovascular or coronary event was defined as a cardiovascular event. The longitudinal follow-up study was conducted with the occurrence of a cardiovascular event as the endpoint. The patients were classified into two groups: an L group with a PWV of less than 10 m/sec and an H group with a PWV of 10 m/sec or higher. Cross-sectional study at baseline: The H group patients were significantly older than the L group patients. The prevalence of hypertension, cardiovascular disease, ischemic heart disease, and cerebrovascular disease were significantly higher in the H group. Systolic blood pressure and serum uric acid were significantly higher in the H group than in the L group. However, there were no significant differences between the two groups with respect to other risk factors. Multivariate analysis using the prevalence of cardiovascular disease as the dependent variable showed "age" and "H group" to be independent variables. When the prevalence of ischemic heart disease or cerebrovascular disease was used as dependent variable, only "age" was an independent variable. Longitudinal follow-up study: The prevalence of cardiovascular event and cerebrovascular event were significantly higher in the H group than in the L group. The prevalence of coronary event in the H group tended to be higher than in the L group, but the difference was not statistically significant. Multivariate analysis using the cardiovascular event rate or coronary event rate as the dependent variable showed only "age" to be an independent variable. When the cerebrovascular event rate was used as the dependent variable, "uric acid" and "H group" were independent variables. The results of this study suggest a higher rate of cerebrovascular disease in patients with high PWV.