Comparison of ultrasound echo-tracking technology and pulse wave velocity for measuring carotid elasticity among hemodialysis patients

Diabetes mellitus type 2 does not influence carotid stiffness in patients on maintenance hemodialysis

Patients on maintenance hemodialysis are a group with high cardiovascular risk, characterized by high arterial stiffness, which is considered a novel cardiovascular risk factor. Diabetes mellitus is both one of the leading causes of end-stage renal disease and a determinant of poor outcome in this group. The aim of the study was to examine carotid stiffness with high resolution echo-tracking in order to assess the influence of diabetes mellitus on arterial stiffness in this group.

Ninety patients (47 F; 43 M) with end-stage renal disease on maintenance hemodialysis were divided into two subgroups: diabetic and nondiabetic (37 and 53 patients respectively). They underwent clinical examination, laboratory tests, and ultrasonographic carotid stiffness assessment both before and after hemodialysis. Local arterial stiffness parameters β, Ep, AC, and PWVβ were calculated. Patient survival was assessed after a 58-month-long follow-up. During the 58-month period 25 of these diabetic patients died, as did 18 non-diabetic patients. Diabetes mellitus was a risk factor for overall mortality among the group of hemodialysed patients. Patients who died from non-cardiovascular causes significantly more often suffered from diabetes mellitus than survivors. There were no statistically significant differences in local arterial stiffness between the groups.

Local arterial stiffness in hemodialysed patients, assessed with high resolution echo-tracking, is not influenced by the presence of diabetes.

Carotid arterial wall stiffness correlates positively with impedance of the umbilical and uterine arteries in women with preeclampsia

PURPOSE

This study aimed to determine whether the stiffness of the arterial walls of women with preeclampsia (PE) differs from that of healthy controls and to evaluate its association with fetal and uterine artery Doppler variables and perinatal outcomes in PE.

METHODS

We enrolled 30 women with PE and 30 normotensive pregnant women. Carotid artery stiffness and Doppler variables of the uterine, umbilical, and fetal middle cerebral arteries and the ductus venosus were measured in both groups. Measurements of the common carotid artery were performed by the Aloka ultrasonic echo-tracking technique.

RESULTS

Stiffness of the carotid artery wall of women with PE was significantly higher than that of healthy controls. It was positively correlated with the pulsatility index of the uterine and umbilical arteries and negatively correlated with the cerebroplacental ratio in women with PE. In women with PE, the carotid artery augmentation index showed negative correlations with birth weight and Apgar score.

CONCLUSIONS

The stiffness of the carotid arteries of women with PE is increased, and this increase is positively correlated with the impedance of the umbilical and uterine arteries.

Correlation between Echo-Tracking Parameters and In Vitro Measurements of Arterial Contraction and Relaxation in Rats Fed a High-Cholesterol Diet

BACKGROUND

Echo-tracking (ET) is a new technique that allows the assessment of arterial function and stiffness. This study aimed to ascertain the utility of the echo-tracking (ET) technique to assess vascular stiffness in rats with hypercholesterolemia and atherosclerosis.

MATERIAL AND METHODS

ET was used to measure the arterial stiffness of the aorta in cholesterol-fed Sprague-Dawley rats (group T1, n=10, for 4 weeks; group T2, n=10, for 12 weeks) and normal control rats (group C1, n=10; group C2, n=10). In vitro isometric tension experiments were used to measure the maximum contractile tension (MCT) and maximum relaxation percentage (MRR%) of aortic rings. Indicators of arterial stiffness and aortic MCT and MRR% were compared between groups using linear regression analysis. Light microscopic evaluation was used to demonstrate atherosclerotic changes in the aorta.

RESULTS

The rat models were successfully induced; pathological examination of the aortas showed significant atherosclerosis in group T2, but not in groups C1, C2, or T1. The arterial stiffness parameters obtained using ET and aortic rings in vitro showed significant impairments in T1 and T2 rats compared with C1 and C2 controls (all P<0.05 vs. controls). In addition, these impairments were greater in the T2 group than in the T1 group (all P<0.05). Finally, MRR% correlated with the distensibility coefficient (r=0.396, P=0.012), arterial compliance (r=0.317, P=0.047), stiffness parameter b (r=-0.406, P=0.009) and one-point pulse wave β (r=-0.434, P=0.005).

CONCLUSIONS

These results suggest that ET could be used to evaluate the changes in arterial wall elasticity associated with atherosclerosis and hypercholesterolemia.

Determinants of arterial stiffness progression in a Han-Chinese population in Taiwan: a 4-year longitudinal follow-up

Background

Arterial stiffness predicts the future risk of macro- and micro-vascular diseases. Only a few studies have reported longitudinal changes. The present study aimed to investigate the progression rate of arterial stiffness and the factors influencing stiffness progression in a Han Chinese population residing in Taiwan.

Methods

The pulse wave velocity (PWV), elasticity modulus (Ep) and arterial stiffness index (β) of the common carotid artery were measured in 577 stroke- and myocardial infarction-free subjects at baseline and after an average interval of 4.2 ± 0.8 years. Stepwise multivariate linear regression was conducted to elucidate the predictors of stiffness progression.

Results

For both baseline and follow-up data, men had significantly higher values of PWV, Ep and β in comparison to women. The progression rates of PWV, Ep and β were faster in men, but the difference was not statistically significant (ΔPWV = 0.20 ± 0.20 and 0.18 ± 0.20 m/s/yr; ΔEp = 8.17 ± 8.65 and 6.98 ± 8.26 kPa/yr; Δβ = 0.70 ± 0.64 and 0.67 ± 0.56 for men and women, respectively). In the multivariate regression analyses, age, baseline stiffness parameters, baseline mean arterial pressure (MAP), baseline body mass index (BMI) and changes in MAP (ΔMAP) were independent predictors of PWV and Ep progression. There was an inverse correlation between the stiffness parameters at baseline and their progression rate (correlation coefficient (r) = −0.12 to −0.33, p = 0.032–1.6 × 10⁻¹⁶). Changes in MAP (ΔMAP) rather than baseline MAP were more strongly associated with PWV progression (p = 8.5 × 10⁻²⁴ and 1.9 × 10⁻⁵ for ΔMAP and baseline MAP, respectively). Sex-specific analyses disclosed that baseline BMI and changes in BMI (ΔBMI) were significantly associated with stiffness progression in men (p = 0.010–0.026), but not in women.

Conclusions

Aging and elevated blood pressure at baseline and during follow-up were the major determinants of stiffness progression in the Han Chinese population. For men, increased baseline BMI and changes in BMI were additional risk factors.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-015-0093-2) contains supplementary material, which is available to authorized users.

Echo-Tracking Method Improves the Reliability in Flow-Mediated Dilation Assessment by Measuring Brachial Artery Reactivity

The purpose of the study was to compare the intraobserver and interobserver reliability and agreement for measurement of flow-mediated dilation (FMD) between B-mode method and echo-tracking (ET) method. Twenty healthy volunteers (mean age, 31.6 ± 9.2 years) underwent ultrasound examination by both B-mode and ET methods. Baseline brachial artery diameter, post-cuff release diameter, and FMD percent were assessed by each sonologist on 2 consecutive days. Reliability was assessed by intraclass correlation coefficients, and Bland-Altman plots were used to visually compare measurement bias and agreement by the 2 ultrasound methods. A total of 40 pairs of data were available for analysis. Excellent intraobserver and interobserver reliability values were found for all variables assessed by the 2 methods. The intraclass correlation coefficient values were higher for ET in both intraobserver and interobserver evaluations, but only for interobserver evaluations for post-cuff release diameter and FMD was there no overlap in the 95% confidence interval. The Bland-Altman plots showed that in 95% of the measurements, the percentage difference between ET and B-mode ultrasound techniques was within 18.1%, 19.4%, and 17.3% for baseline brachial artery diameter, post-cuff release diameter, and FMD percent, respectively. The results suggest that ET and B-mode methods are reproducible in assessing the FMD. The ET method improves the reliability of FMD assessment, but we cannot determine which measurement is better for FMD.