Stiffness of elastic arteries like the aorta predicts cardiovascular risk. By directly reflecting arterial stiffness, having the best predictive value for cardiovascular outcome and the ease of its measurement, carotid-femoral pulse wave velocity is now considered the gold standard for arterial stiffness assessment in daily practice. Many different measurement procedures have been proposed. Therefore, standardization of its measurement is urgently needed, particularly regarding the distance measurement. This consensus document advises on the measurement procedures in general and provides arguments for the use of 80% of the direct carotid-femoral distance as the most accurate distance estimate. It also advises the use of 10 m/s as new cut-off value for carotid-femoral pulse wave velocity.

AimsCarotid–femoral pulse wave velocity (PWV), a direct measure of aortic stiffness, has become increasingly important for total cardiovascular (CV) risk estimation. Its application as a routine tool for clinical patient evaluation has been hampered by the absence of reference values. The aim of the present study is to establish reference and normal values for PWV based on a large European population.Methods and resultsWe gathered data from 16 867 subjects and patients from 13 different centres across eight European countries, in which PWV and basic clinical parameters were measured. Of these, 11 092 individuals were free from overt CV disease, non-diabetic and untreated by either anti-hypertensive or lipid-lowering drugs and constituted the reference value population, of which the subset with optimal/normal blood pressures (BPs) (n = 1455) is the normal value population. Prior to data pooling, PWV values were converted to a common standard using established conversion formulae. Subjects were categorized by age decade and further subdivided according to BP categories. Pulse wave velocity increased with age and BP category; the increase with age being more pronounced for higher BP categories and the increase with BP being more important for older subjects. The distribution of PWV with age and BP category is described and reference values for PWV are established. Normal values are proposed based on the PWV values observed in the non-hypertensive subpopulation who had no additional CV risk factors.ConclusionThe present study is the first to establish reference and normal values for PWV, combining a sizeable European population after standardizing results for different methods of PWV measurement.

Background Experimental and physiologic data mechanistically implicate wave reflections in the pathogenesis of left ventricular failure and cardiovascular disease, but their association with these outcomes in the general population is unclear. Objectives To assess the relationship between central pressure profiles and incident cardiovascular events. Methods Aortic pressure waveforms were derived from a generalized transfer function applied to the radial pressure waveform recorded non-invasively from 5,960 participants in the Multiethnic Study of Atherosclerosis (MESA). The central pressure waveform was separated into forward and reflected waves using a physiologic flow waveform. Reflection magnitude (RM=[reflected/forward wave amplitude] ×100), augmentation index (AIx=[second/first systolic peak] ×100) and pulse pressure amplification (PPA=[radial/aortic pulse pressure] ×100) were assessed as predictors of cardiovascular events (CVE) and congestive heart failure (CHF) during median 7.61 years of follow-up. Results After adjustment for established risk factors, aortic AIx independently predicted hard CVE (HR per 10%-increase=1.08; 95%CI=1.01-1.14; P=0.016), whereas PPA independently predicted all CVE (HR per 10%-increase=0.82; 95%CI=0.70-0.96; P=0.012). RM was independently predictive of all CVE (hazard ratio [HR] per 10%-increase=1.34; 95%CI=1.08-1.67; P=0.009), hard CVE (HR per 10%-increase=1.46; 95%CI=1.12-1.90; P=0.006) and strongly predictive of new-onset CHF (HR per 10%-increase=2.69; 95%CI=1.79-4.04; P<0.0001), comparing favorably to other risk factors for CHF as judged by various measures of model performance, reclassification and discrimination. In a fully-adjusted model, compared to non-hypertensive subjects with low RM, the HR for hypertensive subjects with low RM, non-hypertensive subjects with high RM and hypertensive subjects with high RM were 1.81 (95%CI=0.85-3.86), 2.16 (95%CI=1.07-5.01) and 3.98 (95%CI=1.96-8.05), respectively. Conclusions Arterial wave reflections represent a novel strong risk factor for CHF in the general population.

Abstract-The relation between arterial function indices, such as pulse wave velocity and augmentation index with parameters derived from input impedance analysis, is still incompletely understood. Carotid pressure, central flow waveforms, and pulse wave velocity were noninvasively acquired in 2026 apparently healthy, middle-aged subjects (1052 women and 974 men) 35 to 55 years old at inclusion. Input and characteristic impedance, reflection coefficient, the ratio of backward-to-forward pressure amplitude (reflection magnitude), and augmentation index were derived. Pulse wave velocity increased by 15% (from 6.1 to 7.0 m/s) both in men and women. In qualitative terms, input impedance evolved from a pattern indicative of wave transmission and reflection to a pattern more compatible with a windkessel-like system. In women, a decrease in total arterial compliance led to an increased input impedance in the low frequency range, whereas few changes were observed in men. Characteristic impedance did not change with age in women and even decreased in men (PϽ0.001) and could not be identified as the primary determinant of central pulse pressure. Augmentation index increased with age, as was expected, and was systematically higher in women (PϽ0.001).Reflection coefficient and reflection magnitude increased with age (PϽ0.001) without gender differences. We conclude that, in healthy middle-aged subjects, the age-related increase in arterial stiffness (pulse wave velocity) is not fully paralleled by an increase in arterial impedance, suggesting a role for age-dependent modulation of aortic cross-sectional area. Wave reflection increases with age and is not higher in women than in men. Key Words: cardiovascular physiology Ⅲ blood pressure Ⅲ vascular capacitance Ⅲ arteries Ⅲ biomechanics T he analysis of arterial stiffness and function and of pressure wave reflection received increasing attention for the past 3 decades. Several methods to describe arterial stiffness in a clinical setting emerged, 1 the most investigated being pulse wave velocity (PWV) and augmentation index (AIx). Some aspects related to AIx still need further investigation, such as the systematically higher AIx in women even after adjustment for body size and heart rate, and the observation that AIx tends to levels off to a plateau value above the age of 60 years. 2 Although PWV and AIx are related, they seem to reflect different aspects of arterial function. 2,3 A more global view on the arterial system can be obtained from impedance analysis, 4 -6 requiring measurement of central pressure and flow waveforms. In addition, pressure waveforms (P wf ) can be separated into their forward and backward components. 7 In a recent study in hypertensive patients, Mitchell et al 8 applied impedance analysis and found an increased aortic characteristic impedance (Z c ) to play an important role in the elevated pulse pressure in patients with systolic hypertension. There are no integrated large-scale studies where both impedance analysis and newer indices like PWV and A...

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The relation with age and gender of local and central stiffness measures is not the same over the age range 35-55 in apparently healthy men and women. Depending on the central stiffness parameter used, age-gender effects evident at the carotid artery are or are not found centrally. Though the relevance of these differences requires further evaluation in a longitudinal study with outcome data, they need to be kept in mind when designing or interpreting results from arterial stiffness evaluation studies.

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We recently introduced noninvasive methods to assess local pulse wave velocity (PWV) and wave intensity ((n)dI) in arteries based on measurements of flow velocity (U) and diameter (D). Although the methods were validated in an experimental setting, clinical application remains lacking. The aim of this study was therefore to investigate the effect of age and gender on PWV and (n)dI in the carotid and femoral arteries of an existing population. We measured D and U in the carotid and femoral arteries of 1,774 healthy subjects aged 35-55 yr, a subgroup of the Asklepios population. With the use of the lnDU-loop method, we calculated local PWV, which was used to determine arterial distensibility ((n)Ds). We then used the new algorithm to determine maximum forward and backward wave intensities ((n)dI(+max) and (n)dI(-min), respectively) and the reflection index ((n)RI). On average, PWV was higher, and (n)Ds was lower in the femoral than at the carotid arteries. At the carotid artery, PWV increased with age, but (n)Ds, (n)dI(+max), and (n)dI(-min) decreased; (n)RI did not change with age. At the femoral artery, PWV was higher, and (n)Ds was lower in male, but all parameters did not change significantly with age in both women and men. We conclude that the carotid artery is more affected by the aging process than the femoral artery, even in healthy subjects. The new techniques provide mechanical and hemodynamic parameters, requiring only D and U measurements, both of which can be acquired using ultrasound equipment widely available today, hence their advantage for potential use in the clinical setting.