The stiffness parameter β assessed by an ultrasonic phase-locked echo-tracking system is associated with plaque formation in the common carotid artery

Assessment of factors affecting flicker ERGs recorded with RETeval from data obtained from health checkup screening

PURPOSE

To determine the factors significantly associated with the amplitudes and implicit times of the flicker electroretinograms (ERGs) recorded with the RETeval system by analyzing the comprehensive data obtained during a health checkup screening.

METHODS

Flicker ERGs were recorded with the RETeval system from 373 individuals who had a normal fundus and optical coherence tomography images. The sex, age, anthropometric, ophthalmologic, and hematologic data were collected from all participants who were 40- to 89-years-of-age. Univariable and multivariable linear mixed effects regression analyses were performed to identify factors that were significantly associated with the implicit times and amplitudes of the RETeval flicker ERGs.

RESULTS

Univariable linear mixed effects regression analysis showed significant correlations between the implicit times and the best-corrected visual acuity, the age, the axial length, the blood sugar level, and the blood urea nitrogen level. Analyses by multivariable linear mixed effects regression identified that the axial length (β = 0.28), the age (β = 0.24), and the blood sugar level (β = 0.092) were three independent factors that were significantly correlated with the implicit times of the RETeval flicker ERGs. Univariable linear mixed effects regression analysis also showed significant correlations between the amplitudes of the RETeval flicker ERGs and the age, the platelet count, and the creatinine level. Multivariable linear mixed effects regression models identified the age (β = -0.092), the platelet count (β = 0.099), and the creatinine level (β = -0.12) as three independent factors that were significantly correlated with the amplitudes of the RETeval flicker ERGs. However, the smoking habits, body mass index, and the blood pressure were not significantly correlated with either the implicit times or amplitudes of the RETeval flicker ERGs.

CONCLUSIONS

Our results indicate that the age and some ophthalmologic and hematologic findings but not the anthropometric findings were significantly associated with the implicit times and amplitudes of the RETeval flicker ERGs. Thus, clinicians should remember these factors when analyzing the RETeval flicker ERGs.

Evaluation of local changes in radio-frequency signal waveform and brightness caused by vessel dilatation for ascertaining reliability of elasticity estimation inside heterogeneous plaque: a preliminary study

PURPOSE

To diagnose plaque characteristics, we previously developed an ultrasonic method to estimate the local elastic modulus from the ratio of the pulse pressure to the strain of the arterial wall due to dilatation in systole by transcutaneously measuring the minute thinning in thickness during one cardiac cycle. For plaques, however, some target regions became thicker as the vessel dilates, resulting in false elasticity. Therefore, a method to identify a reliable target for the elastic modulus estimation is indispensable. As a candidate for an identification index of plaques that become thicker during one cardiac cycle, the correlation of the radio-frequency (RF) signals remains high and it is not sufficient to obtain the elasticity. In this study, we thoroughly observed the target with a high correlation but positive strain in the plaque and characterized it by the property of the surrounding area.

METHODS

For the plaque formed in the right carotid sinus of a patient with hyperlipidemia and the wall of the right common carotid artery of a young healthy male, (1) the correlation value as the similarity between the RF signals, (2) change in brightness obtained from the log-compressed envelope signals, and (3) strain obtained between the time of the R-wave and that of the maximum vessel dilatation were observed to characterize the region in the plaque.

RESULTS

In the plaque, it was found that the region with high correlation and positive strain and its surrounding area could be classified into one of the three typical patterns.

CONCLUSION

As a preliminary study, this study provides a clue to assert the reliability of elasticity estimates for a region with high correlation and positive strain in the plaque based on measurable properties.

Is Stiffness Parameter β Useful for the Evaluation of Atherosclerosis?~ Its Clinical Implications, Limitations, and Future Perspectives ~

Atherosclerosis comprises two components, atherosis and sclerosis, characterized by morphological wall thickening and functional stiffening, respectively, of the arterial wall. In recent years, much interest has been directed to the role of functional changes in large arteries, i.e., increased stiffness or decreased elasticity, on the development of cardiovascular diseases. In fact, the clinical evaluation of arterial stiffness is increasingly performed in patients with cardiovascular risk factors. Local arterial stiffness is measured using an ultrasound technique implemented with an echo-tracking system at the common carotid and femoral arteries. Several indices of local arterial stiffness are obtained by ultrasound, among which stiffness parameter β is unique because it is the least affected by blood pressure at the time of measurement. Evidence from cross-sectional studies indicates that increased stiffness parameter β is associated with a number of cardiovascular risk factors, such as older age, smoking, insufficient physical activity, hypertension, obesity, metabolic syndrome, insulin resistance, type 2 diabetes, chronic kidney disease, and comorbid cardiovascular disease. Results from several prospective observational studies also suggest that carotid stiffness parameter β is a useful surrogate marker of cardiovascular events and/or mortality, although the results differ depending on the characteristics of the study subjects. Furthermore, several interventional studies have shown that carotid stiffness parameter β improved after lifestyle modification or drug treatment. In this review, we summarize the current evidence of stiffness parameter β of the carotid artery and discuss its clinical implications as a marker of vascular health or as a predictor of cardiovascular outcomes.

Circulating Vascular Cell Adhesion Molecule-1 (VCAM-1) and Intercellular Adhesion Molecule-1 (ICAM-1): Relationship with carotid artery elasticity in patients with impaired glucose regulation (IGR)

OBJECTIVE

To investigate the relations of circulating adhesion molecule vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) with carotid artery elasticity in patients with impaired glucose regulation (IGR).

METHODS

A total of 208 subjects were enrolled from January 2013 to March 2014. One hundred forty-eight were IGR patients, and 60 had normal glucose tolerance (NGT). Carotid intima-media thickness (IMT), carotid artery pressure-strain elasticity coefficient (Eρ), stiffness (β), arterial compliance (AC), and pulse wave velocity (PWVβ), as well as blood pressure, body mass index, blood glucose, blood lipids, insulin resistance index, VCAM-1, and ICAM-1 were measured and compared between IGR and NGT patients.

RESULTS

Eρ, β and PWVβ were significantly higher in the IGR group than in the NGT group (P<0.05), but the IMT showed no significant difference (P>0.05). VCAM-1 and ICAM-1 were significantly higher in the IGR group than in the NGT group (P<0.05). VCAM-1 and ICAM-1 were positively correlated with Eρ, β, and PWVβ and negatively correlated with AC in IGR patients.

CONCLUSIONS

Changes in carotid artery elasticity and endothelial dysfunction are found in patients with IGR. Early comprehensive intervention should be performed in such IGR populations.

Oxidized human serum albumin as a possible correlation factor for atherosclerosis in a rural Japanese population: the results of the Yakumo Study

Background

The effect of the redox state of human serum albumin (HSA) on the antioxidant properties of the entire body has been a focus of recent research. The usefulness of HSA redox state as a biomarker for reducing oxidative stress has been investigated in clinical settings; however, evidence for its significance as a health index in non-clinical settings is yet to be established. This study aimed to examine the associations between HSA redox state and the atherosclerotic indices of carotid intima-media thickness (IMT) and plaque formation in a rural Japanese population.

Methods

We conducted a cross-sectional study as part of a health check-up program in the rural area of Hokkaido, Japan, at the end of August 2013. A total of 281 residents (124 men and 157 women) were included in the final analysis. Lifestyle-related data were obtained through a self-reported questionnaire, and ultrasound examinations were performed to measure IMT and determine plaque formation. The high-performance liquid chromatography postcolumn bromocresol green method was used to separate HSA into human nonmercaptalbumin and human mercaptalbumin (HMA).

Results

We found a significant negative relationship between the fraction of HMA [f(HMA)] and IMT (standardized β = − 0.132, p = 0.03). Moreover, f(HMA) was significantly associated with plaque formation (p < 0.01) with an odds ratio of 0.89 (95% confidence interval, 0.81–0.97) for every 10% increment in f(HMA).

Conclusions

We found that the HSA redox state, as determined by f(HMA), was associated with atherosclerotic indices in Japanese subjects. These results suggest that the HSA redox state indicates the risk of developing atherosclerosis.

Impact of biological aging on arterial aging in American Indians: findings from the Strong Heart Family Study

Telomere length, a marker of biological aging, has been associated with cardiovascular disease (CVD). Increased arterial stiffness, an indicator of arterial aging, predicts adverse CVD outcomes. However, the relationship between telomere length and arterial stiffness is less well studied. Here we examined the cross-sectional association between leukocyte telomere length (LTL) and arterial stiffness in 2,165 American Indians in the Strong Heart Family Study (SHFS). LTL was measured by qPCR. Arterial stiffness was assessed by stiffness index β. The association between LTL and arterial stiffness was assessed by generalized estimating equation model, adjusting for sociodemographics (age, sex, education level), study site, metabolic factors (fasting glucose, lipids, systolic blood pressure, and kidney function), lifestyle (BMI, smoking, drinking, and physical activity), and prevalent CVD. Results showed that longer LTL was significantly associated with a decreased arterial stiffness (β=-0.070, P=0.007). This association did not attenuate after further adjustment for hsCRP (β=-0.071, P=0.005) or excluding participants with overt CVD (β=-0.068, P=0.012), diabetes (β=-0.070, P=0.005), or chronic kidney disease (β=-0.090, P=0.001). In summary, shorter LTL was significantly associated with an increased arterial stiffness, independent of known risk factors. This finding may shed light on the potential role of biological aging in arterial aging in American Indians.

A systematic literature review of the effect of carotid atherosclerosis on local vessel stiffness and elasticity

OBJECTIVE

This systematic literature review sought to determine the effects of carotid atherosclerotic plaque on local arterial stiffness.

METHODS

MedLine, EMBASE, and grey literature were searched with the following term: ("atherosclerosis" or "carotid atherosclerosis" or "carotid artery disease" or "carotid plaque") AND ("distensibility" or "elasticity" or "stiffness" or "compliance") NOT ("pulse wave velocity" or "PWV" or "carotid-ankle" or "ankle-brachial" or "augmentation index" or "cardio-ankle" or "CAVI" or "flow mediated dilation" or "FMD"). Results were restricted to English language articles reporting local arterial stiffness in human subjects with carotid atherosclerosis.

RESULTS

Of the 1466 search results, 1085 abstracts were screened and 191 full-text articles were reviewed for relevance. The results of the 50 studies that assessed some measure of carotid arterial elasticity or stiffness in patients with carotid plaque were synthesized and reviewed.

DISCUSSION

A number of different measures of carotid elasticity were found in the literature. Regardless of which metric was used, the majority of studies found increased carotid stiffness (or decreased distensibility) to be associated with carotid plaque presence, the degree of atherosclerosis, and incident stroke.

CONCLUSION

Carotid artery mechanics are influenced by the presence of atherosclerotic plaque. The clinical applicability of carotid elasticity measures may be limited by the lack of reference values and standardized techniques.