Measurement Of Arterial Elasticity Research Articles

A combined measure of vascular risk for white matter lesions.

Though hypertension is a commonly studied risk factor for white matter lesions (WMLs), measures of blood pressure may fluctuate depending on external conditions resulting in measurement error. Indicators of arterial stiffening and reduced elasticity may be more sensitive indicators of risk for WMLs in aging; however the interdependent nature of vascular indicators creates statistical complications. The purpose of the study was to determine whether a factor score comprised of multiple vascular indicators would be a stronger predictor of WMLs than traditional measures of blood pressure. In a sample of well-characterized nondemented older adults, we used a factor analytic approach to account for variance common across multiple vascular measures while reducing measurement error. The result was a single factor score reflecting arterial stiffness and reduced elasticity. We used this factor score to predict white matter lesion volumes acquired via fluid attenuated inversion recovery (FLAIR) magnetic resonance imaging. The combined vascular factor score was a stronger predictor of deep WML (β = 0.42, p < 0.001) and periventricular WML volumes (β = 0.49, p < 0.001). After accounting for the vascular factor, systolic and diastolic blood pressure measurements were not significant predictors. This suggests that a combined measure of arterial elasticity and stiffening may be a stronger predictor of WMLs than systolic and diastolic blood pressure accounting for the multicollinearity associated with a variety of interrelated vascular measures.

Assessment of arterial elasticity among HIV-positive participants with high CD4 cell counts: a substudy of the INSIGHT Strategic Timing of AntiRetroviral Treatment (START) trial.

Both HIV infection and antiretroviral therapy (ART) may increase cardiovascular disease (CVD) risk. Assessments of vascular function and structure can be used to study the pathogenesis and progression of CVD, including the effects of ART and other interventions. The objective of this report is to understand methods to assess vascular (dys)function and report our experience in the Arterial Elasticity Substudy in the Strategic Timing of AntiRetroviral Treatment (START) trial. We review literature and analyze baseline data from the Arterial Elasticity Substudy, which estimated vascular (dys)function through analysis of the diastolic blood pressure (BP) waveform. Linear regression was used to study cross-sectional associations between baseline clinical factors and small or large arterial elasticity. Arterial elasticity measurement was chosen for its improved measurement reproducibility over other methodologies and the potential of small arterial elasticity to predict clinical risk. Analysis of baseline data demonstrates that small artery elasticity is impaired (lower) with older age and differs by race and between geographical regions. No HIV-specific factors studied remained significantly associated with arterial elasticity in multivariate models. Longitudinal analyses in this substudy will provide essential randomized data with which to study the effects of early ART initiation on the progression of vascular disease among a diverse global population. When combined with future biomarker analyses and clinical outcomes in START, these findings will expand our understanding of the pathogenesis of HIV-related CVD.

Early pregnancy maternal cardiovascular profiling in the prediction of hypertensive disease in pregnancy

Prediction of hypertensive disease in pregnancy remains challenging. Risk factor based screening utilizing history, physical characteristics, uterine artery Doppler and serum markers have been used with varying success. As hypertension in pregnancy appears to be associated with changes in the maternal vasculature, we have investigated the utility of maternal arterial elasticity measurement, prior to 20 weeks gestation, in the prediction of hypertensive disease in pregnancy. A HDI/Pulsewave CR2000 Research Cardiovascular Profiling System was used to obtain radial artery pulse pressure waveforms from 623 Caucasian women at the time of their first antenatal visit. Outcome data were available in 610 cases and these comprised the study group. The results showed that women who subsequently developed gestational hypertension (n = 20) had higher baseline systolic, diastolic and pulse pressure values (though within the normal range) but similar arterial elasticity to those patients who did not develop hypertension. Women who later developed pre-eclampsia (n = 23) had, in addition, reduced large artery elasticity and increased systemic vascular resistance compared with women who did not develop hypertension. The measurement of maternal radial artery elasticity in early pregnancy may provide an additional refinement in screening for hypertensive disease, particularly pre-eclampsia, in pregnancy.

Arterial Elasticity Measurement in Patients with Behcet's Disease

Arterial Elasticity Measurement in Patients with Behcet's Disease

Association of resting heart rate with carotid and aortic arterial stiffness: multi-ethnic study of atherosclerosis.

Resting heart rate is an easily measured, noninvasive vital sign that is associated with cardiovascular disease events. The pathophysiology of this association is not known. We investigated the relationship between resting heart rate and stiffness of the carotid (a peripheral artery) and the aorta (a central artery) in an asymptomatic multi-ethnic population. Resting heart rate was recorded at baseline in the Multi-Ethnic Study of Atherosclerosis (MESA). Distensibility was used as a measure of arterial elasticity, with a lower distensibility indicating an increase in arterial stiffness. Carotid distensibility was measured in 6484 participants (98% of participants) using B-mode ultrasound, and aortic distensibility was measured in 3512 participants (53% of participants) using cardiac MRI. Heart rate was divided into quintiles and we used progressively adjusted models that included terms for physical activity and atrioventricular nodal blocking agents. Mean resting heart rate of participants (mean age, 62 years; 47% men) was 63 bpm (SD, 9.6 bpm). In unadjusted and fully adjusted models, carotid distensibility and aortic distensibility decreased monotonically with increasing resting heart rate (P for trend <0.001 and 0.009, respectively). The relationship was stronger for carotid versus aortic distensibility. Similar results were seen using the resting heart rate taken at the time of MRI scanning. Our results suggest that a higher resting heart rate is associated with an increased arterial stiffness independent of atrioventricular nodal blocker use and physical activity level, with a stronger association for a peripheral (carotid) compared with a central (aorta) artery.

Sex Differences in Cardiovascular Disease Risk in Adolescents With Type 1 Diabetes

Cardiovascular disease is seen at a younger age and at a higher prevalence in patients with type 1 diabetes than in the general population. It is well described that women with type 1 diabetes have a higher relative risk of cardiovascular disease than men with type 1 diabetes, unlike that seen in the general population. The pathophysiology behind this is unknown. We performed a cross-sectional study to examine sex differences in cardiovascular disease risk factors in adolescents with type 1 diabetes between ages 13 and 20 years, compared with children of a similar age without type 1 diabetes. All patients underwent a dual energy x-ray absorptiometry scan to measure body composition and a pulse wave test measure of arterial elasticity. Fasting serum lipid levels, apolipoprotein B, and apolipoprotein C-III levels were measured in each patient. Twenty-nine children with type 1 diabetes (10 girls, 19 boys) and 37 healthy children (18 girls, 19 boys) participated. Although no sex differences for body mass index (P = 0.91) and glycosylated hemoglobin (P = 0.69) were seen, girls with type 1 diabetes had a significantly higher percent trunk fat compared with boys (P = 0.004). No sex differences were found (P > 0.05) for percent trunk fat in adolescents without diabetes. There was no sex difference among any other cardiovascular risk factors in either children with or without diabetes. Female adolescents with type 1 diabetes have more centrally distributed fat, which may contribute to their relatively higher cardiovascular disease risk. Attenuation of the central distribution of fat through exercise and dietary modifications may help ameliorate their subsequent cardiovascular disease burden.

Two-dimensional multi-layer of arterial elasticity measurement considering geometric transformations

Knowledge of the arterial elasticity can provide an important reference for understanding arterial wall changes that may occur before and during the early stages of atherosclerosis. In practice, the movements of arterial wall during the cardiac cycle are complex, which undergo not only translation but also rotation and deformation subjected to pulse pressure, transmural pressure and shear force. Conventional correlation based methods for arterial wall movement evaluation consider only the translational component and limit their accuracy. This study proposes a texture matching method based on ultrasonic B-mode image for accurately measurement the movement of the arterial wall with geometric transformations, improving the accuracy of elasticity measurement. Feasibility of the method was studied in an in vitro silicone tube phantom and in vivo carotid arteries of mice. The calculated elastic modulus for the in vitro silicone tube agrees well with the results obtained from mechanical testing, deviating only 6...

Pulse pressure amplification in relation to body fatness

Aortic-brachial pulse pressure amplification (PPA) is a measure of arterial elasticity and it is also an independent cardiovascular risk factor. The PPA is mainly determined by age, height, central and peripheral pressure waveforms characteristics, including measures of arterial stiffness and wave reflection. In this study, however, we demonstrate that PPA is also significantly associated with indirect indices of body fatness. As the body fatness is treatable, our findings might be used as a reference for future studies on the effects of body fat reduction on PPA and the PPA-related cardiovascular risk. AIMS Arterial pressure transfer to the periphery is accompanied by pulse pressure amplification (PPA). Pulse pressure is influence by body fat. The purpose of the present study was to evaluate any possible inter-relation between body fatness and PPA in healthy subjects. Haemodynamic and wave reflection indices were estimated by pulse wave analysis. Body fat was measured by bio-impedance. A total of 367 healthy volunteers (136 men and 231 women) was studied. Pulse pressure amplification correlated significantly with percentage of body fat (r=-0.53, P < 0.0001), age (r=-0.62, P < 0.0001), height (r= 0.43, P < 0.0001), heart rate (r= 0.28, P < 0.0001) and mean blood pressure (r=-0.29, P < 0.0001). The association of PPA with body fat was also significant in a multiple linear regression model. Age was an independent predictor of PPA and analysis of study subjects subdivided into two groups, those <50 years and those >50 years showed that body fatness correlated inversely and significantly with PPA in individuals both younger and older than 50 years (r=-0.44, P < 0.0001, r=-0.37, P < 0.0001 respectively). Augmentation pressure was also associated significantly with percentage of body fat in both subgroups (r= 0.48, P < 0.0001 and r= 0.49, P < 0.0001 respectively). This study performed on healthy subjects showed that pulse pressure amplification is related to body fatness over a wide age range. Percentage body fat is significantly associated with augmentation pressure, a component of central pulse pressure.

A Texture Matching Method Considering Geometric Transformations in Noninvasive Ultrasonic Measurement of Arterial Elasticity

Measurement of arterial elasticity can provide an important reference for understanding arterial wall changes that may occur in the early stages of atherosclerosis. Conventional correlation-based methods for evaluating arterial wall movements consider only the translation, ignoring the rotation and deformation, which limits the accuracy of measurement of arterial displacement and its biomechanical properties. This article proposes a novel texture matching method based on ultrasonic B-mode image considering geometric transformations to accurately measure arterial displacement and acquire arterial elasticity noninvasively. The method was validated by simulated images with rotation and deformation and further by measurements in vitro arterial phantom and in vivo common carotid arteries of 20 healthy volunteers. Simulation results demonstrate that the method can improve the accuracy of measurement of arterial displacement. Experimental results show that the elastic modulus of the arterial phantom agrees well with the results obtained from mechanical tests, deviating only 4.1%. The mean elastic modulus of the common carotid arteries is 361.7 ± 93.5 kPa. The texture matching method was shown to be able to measure the displacement and elasticity of the arterial wall with complex geometric transformations and may be clinically useful for early detecting and monitoring atherosclerosis.

Age estimation based on a combined arteriosclerotic index

This study introduces a new quantity, the combined arteriosclerotic index (CAI), which is defined as the ratio between the diameter and the longitudinal prestrain of an artery. The longitudinal prestrain has been adopted as the ratio between the in situ length and the excised length of the abdominal aorta, and is a measure of arterial elasticity. During ageing, arteriosclerosis is manifested by the loss of pretension and by enlargement of the diameter of the artery. CAI combines these two effects. A sample of 61 female and 194 male autopsy measurements of human abdominal aortas shows that CAI correlates significantly with chronological age (R = 0.916/0.921; female/male). The sample had the following parameters: age 53 ± 19/48 ± 16 years; diameter of the abdominal aorta 12.4 ± 2.2/13.4 ± 2.1 mm; and longitudinal prestrain 1.13 ± 0.10/1.15 ± 0.10 (mean ± sample standard deviation; female/male). The resulting CAI was 11.2 ± 2.7/11.9 ± 2.6 mm. The classical linear regression model was employed for age estimation by CAI. The model gave a residual standard deviation of 7.6/6.3 years and a 95% prediction interval range of ± 15.4/12.5 years (female/male). A two-sample t-test confirmed that there are significant differences between the female and male population during ageing, reflected by CAI, unlike longitudinal prestrain. It was concluded that CAI is a suitable predictor of age at time of death and is easily obtainable in the autopsy room.

Vascular Compliance is Reduced in Geriatric People with Angiographic Coronary Atherosclerosis

This study investigated the value of arterial elasticity measurement in the early diagnosis of angiographic coronary artery atherosclerosis in 105 consecutive elderly patients. They were divided into two groups according to the results of selective coronary angiography: 55 with coronary atherosclerosis and 50 with a normal coronary angiogram. The Gensini score of the coronary artery was acquired and capacitive arterial compliance (C1) and oscillatory arterial compliance (C2) were measured. An independent-sample t-test was used to evaluate the difference in C1 and C2 between the two groups. Bivariate analyses were performed to study the association between the Gensini score and C1 and C2. A significant difference between the two groups in C2 was found and the Gensini score of the coronary artery was significantly correlated with C2. Identification of early coronary atherosclerosis in geriatrics may be aided by the prognostic value of C2.

Evaluation of Plaque Stabilization by Fluvastatin with Carotid Intima- Medial Elasticity Measured by a Transcutaneous Ultrasonic-Based Tissue Characterization System

As an approach to tissue characterization, we attempted to classify in vivo carotid plaque tissues in terms of arterial wall elasticity instead of echogenicity on B-mode scanning and investigated whether the effect of fluvastatin on carotid elasticity can be detected in hypercholesterolemic patients. In 170 subjects, simultaneous measurements of intima-media thickness (IMT) and elastic modulus in the circumferential direction (E(theta)) were performed using a new transcutaneous high-resolution Doppler technique. From the observation of various tissues, an elasticity library was obtained as follows: lipid core, 22+/-15 kPa; calcification, 674+/-384 kPa; lipid core- and calcification-free plaques, 173+/-69 kPa; smooth muscle, 104+/-32 kPa; blood clot, 85+/-68 kPa; fibrosis, 273+/-173 kPa.The effect of fluvastatin (30 mg/day, n=62) was assessed over 12 months using the elasticity distribution and serum markers. The statin reduced low-density lipoprotein cholesterol, high-sensitivity CRP, mean IMT and mean E(theta), and increased nitrite/nitrate. In the max IMT > or =1.1 mm group, both E(theta) and IMT decreased significantly. On the other hand, in the max IMT <1.1 mm group, E(theta) but not IMT decreased significantly. The histogram of the subgroups showing increased E(theta) with max IMT> or =1.1 mm revealed a decrease in areas corresponding to E(theta) of 20200 kPa (lipid/smooth muscle-rich tissue) and an increase in relatively hardened areas of <250 kPa (collagen fibers). Non-invasive echographic carotid arterial elasticity measurement is useful for the classification of atherosclerotic plaques and evaluation of chronological and histopathological changes.

Association between arterial elasticity, C-reactive protein and maximal oxygen consumption in well-trained cadets during three days extreme physical load: a pilot study

Regular aerobic training has beneficial effects on inflammatory pathways and on arterial elasticity, which are both important cardiovascular risk factors. The aim of the present study was to evaluate the effect of extreme physical load on arterial elasticity and inflammatory markers in well-trained healthy men who participated in a high-ranking combat course. Seven well-trained male cadets were examined during an international military combat course of 3.5 days duration. Small (C2) and large (C1) artery elasticity was assessed using diastolic pulse wave analysis. Inflammatory markers and arterial elasticity measurement were performed before and after the competition. The extreme prolonged physical load caused individually different responses in arterial elasticity, C-reactive protein (CRP) and creatine kinase in individual cadets. Maximal oxygen consumption (VO2 max kg−1) correlated significantly with the change (Δ-difference between baseline and 24 h recovery period) of creatine kinase (r = −0.78; p = 0.04) and ΔC2 (r = 0.78; p = 0.04) and ΔC1 (r = 0.82; p = 0.02). In multivariate analysis (R2 = 0.89, p = 0.01) the ΔC2 correlated strongly with VO2 max kg−1 (p = 0.005) and with the ΔCRP (p = 0.03), whereas the ΔC1 correlated only with VO2 max kg−1 and did not correlate significantly with the ΔCRP. Changes in small arterial elasticity induced by extreme physical load were significantly related to VO2 max kg−1 and ΔCRP, whereas the change of large artery elasticity was only associated with VO2 max kg−1. Our preliminary results indicate that acute exercise-induced inflammation may affect small artery elasticity. However, further, more extensive studies are needed in this area.

Arterial Elasticity Measurement in Renal Transplant Recipients

Arterial distensibility is reduced in chronic kidney disease (CKD) and after kidney transplantation. Pulse counter analysis provides an assessment of compliance or elasticity of the large conduit arteries (C1) and small arteries (C2). Decreased compliance has been shown to be predictive of primary coronary events in CKD patients. The aim of the present study was to compare elasticity measurements in hemodialysis (HD) patients, renal transplant recipients (RTR), and healthy subjects whose coronary angiographies were without lesion. Twenty-three RTRs, 18 HD patients, and 20 healthy subjects were included in the study. Pulse wave analysis was used to determine large and small vessel compliances. The C1 and C2 levels were significantly lower in HD patients compared with recipients and healthy subjects. Recipients showed lower C2 level compared with healthy subjects. There was no difference in C1 and C2 measurements between recipients receiving tacrolimus versus cyclosporine. Transplantation improves large and to some extend small artery elasticities in CKD patients.

Validation of a device to measure arterial pulse wave velocity by a photoplethysmographic method

We aimed to validate a new method for measuring arterial pulsewave transit time and pulsewave velocity (a measure of arterial elasticity), based on the principle of photoplethysmography (PPG), and to compare transcutaneous values with those obtained by intra-arterial measurements. Three validation experiments are described. (a) PPG pulse wave delay times (defined as the time interval between the ECG R wave and the foot of the arterial pulse wave measured at the wrist or ankle) were compared to values obtained simultaneously from an established methodology (Doppler ultrasound). (b) Aortic pulsewave delay times in 17 subjects obtained non-invasively by the PPG method were compared with those obtained from the intra-arterial pressure wave. (c) Repeatability measurements of PWV on the same subjects were carried out over two timescales (minutes and hours) in the arm, the leg and the trunk. The Doppler and PPG delay times correlated well, as did intra-arterial and transcutaneous values. Repeatability at short timescales was good (coefficients of variation (CV) <6% for all measurement sites) and, at the longer timescale, was satisfactory (CVs in the aorta, the arm and leg were 6.3, 13.1 and 16.0, respectively). The PWV values agreed well with others in the literature.We conclude that the PPG technique provides a complement to existing methods for the non-invasive measurement of arterial compliance. Its simplicity and ease of use make it suitable for large-scale epidemiological studies.

Noninvasive measurement of arterial elasticity in various human limbs.

Arterial elasticity expressed by such indices as volume elastic modulus Ev and compliance Ca were noninvasively measured in various human limb segments; the upper arms, forearms, fingers, thighs, calves and toes. These indices are defined, respectively, as\(E_v = \Delta P/(\Delta V/\bar V_a )\) and Ca=ΔV/ΔP, where ΔP is pulse pressure,\(\bar V_a \) mean arterial volume and ΔV its pulsatile variation. ΔP was calculated from systolic Pas and mean Pam arterial pressures determined by volume oscillometric sphygmomanometry using the following equation:\(\Delta P = 3(P_{as} - P_{am} )/2\bar V_a \) and the ΔV were detected by electrical admittance plethysmography at various transmural pressure Pt levels controlled by a compression cuff. The values obtained in these limb segments were compared with each other at Pt levels 0,30 and 60 mm Hg and the differences between them were discussed.

Noninvasive automatic measurement of arterial elasticity in human fingers and rabbit forelegs using photoelectric plethysmography.

A new instrument for the noninvasive measurement of arterial elastic properties such as ‘pressure-volume relationship’ and ‘volume elastic modulus’ in human fingers or in rabbit forelegs has been designed using a transmittance infra-red photoelectric plethysmography technique. The measurement and display of the results by this system is carried out automatically by use of a conventional personal computer. Using this instrument, the progressive and regressive changes in arterial elastic properties have been clearly demonstrated in the forelegs of hyperlipoedemic rabbits with experimental atherosclerosis. The effect of vasodilation by isosorbide dinitrate on the finger arteries of patients with congestive heart failure was also successfully studied. This instrument is capable of a rapid and reliable measurement of arterial elasticity and appears to be useful not only in basic cardiovascular research laboratories but also in clinics.