Correction of carotid intima-media thickness for adaptive dependence on tensile stress: implication for cardiovascular risk assessment

Assessment of Sonographic Carotid Parameters in Autism Spectrum Disorder: A Comparative Case Control Study

OBJECTIVE

To compare carotid intima-media thickness (cIMT), systolic and diastolic diameters (D), intima-media thickness/diameter ratio (IDR) values in children with ASD, and control groups, and to analyze the correlation of these parameters with the Childhood Autism Rating Scale (CARS) scores.

METHODS

This prospective case-control study included 37 children diagnosed with ASD and 38 individuals without ASD in the control group. Correlation assessments of sonographic measurements with CARS scores in the ASD group were also performed.

RESULTS

Diastolic diameters of the right (median of ASD group:5.5 mm, control group:5.1 mm) and left (median of ASD group: 5.5 mm, in control group: 5.1 mm) side were higher in the ASD group (p = .015 and p = .032 respectively). A statistically significant correlation was detected between CARS score and left cIMT, right cIMT, right cIMT/systolic D, right cIMT/diastolic D, left cIMT/systolic D, and left cIMT/diastolic D (p < .05).

CONCLUSION

Vascular diameters, cIMT, and IDR values of children with ASD positively correlated with CARS scores, and these findings could be interpreted as a marker of early atherosclerosis in children with ASD.

Vascular diameter and intima-media thickness to diameter ratio values of the carotid artery in 642 healthy children

In children, arterial alterations occur with increased intima-media thickness as well as vascular diameter enlargement. Both conditions correlate with higher cardiovascular risk in adults, and both the array and proportion of these alterations are important hemodynamic parameters. In terms of functional adaptation processes, they influence several arterial wall properties as for example the shear and tensile stress of the vessel. There are no reference values for the vascular diameter and intima-media thickness/diameter ratio of the carotid artery in children. Therefore, this study aimed to assess vascular diameter, intima-media thickness/diameter ratio and related tensile stress values in children and to further investigate the influence of sex, age, body mass index, and blood pressure. The parameters were measured with high-resolution semi-automated ultrasound. Sex- and age-dependent values were calculated with the LMS method for a cross-sectional sample of 642 healthy, non-obese children aged 8-17 years. The mean vascular diameter was 5.45 ± 0.46 mm; the median intima-media thickness/diameter ratio was 0.085 (0.079-0.092); the median tensile stress was 105.4 (95.2-116.4) kPa. The vascular diameter and the tensile stress were higher, and the intima-media thickness/diameter ratio was lower in boys than in girls. In comparison to the normal weight study population the excludedobese children had a significantly higher diameter, a lower intima-media thickness/diameter ratio, and a higher tensile stress. In multiple regression analyses of diameter, intima-media thickness/diameter ratio, and tensile stress, all parameters were influenced by sex and body mass index. Furthermore, systolic and diastolic blood pressure significantly influenced the vascular diameter, and systolic blood pressure significantly influenced the intima-media thickness/diameter ratio. Conclusion: This study is the first to report values for the diameter, the intima-media thickness/diameter ratio of the carotid artery, and the related tensile stress allowing a more differentiated view of cardiovascular adaptations as it combines structural and functional vascular parameters. What is known: • Intima-media thickness and vascular diameter are related to a higher cardiovascular risk in adults • The intima-media thickness/diameter ratio gives information about hemodynamic and functional vessel adaptation What is new: • Values for vascular diameter, intima-media thickness/diameter ratio, and tensile stress of the carotid artery in children are presented in this study • Intima-media thickness as a surrogate marker for arterial health in children should be complemented by intima-media thickness/diameter ratio measurement.

Ultrasound assessment of tensile stress in carotid arteries of healthy human subjects with varying age

Background

Arterial remodeling is thought to reflect the adaptation of the vessel wall to mechanical and hemodynamic stimuli and contributes to the progression of cardiovascular and cerebrovascular diseases. Tensile stress (TS) is one of the mechanical properties of the artery wall. The purpose of this study was to investigate the tensile stress change (TS) of carotid artery with varying viscoelasticity in healthy subjects within two groups of different ages.

Methods

Forty-five subjects were recruited and randomly assigned into the group at the age above 50 years and below 50 years. The carotid arteries were examined by ultrasonography, using the techniques of shear wave elastography (SWE), shear wave dispersion (SWD) and radiofrequency (RF) -based ultrasound. The following values, including elastic modulus (SWER) and viscous index (SWDR), as well as the peak and mean TS of the left and right carotid arteries (L-PTS, R-PTS, L-MTS and R-MTS) were measured. The correlations between SWER, SWDR and tensile stress were evaluated.

Results

The SWE_R and SWD_R of carotid arteries are lower in the subjects ≥50 years old than the subjects younger than 50 years (SWE_R, 10.29 ± 9.57 kPa VS 17.24 ± 14.07 kPa; SWD_R, 11.99 ± 3.51 (m/s)/kHz VS 13.97 ± 3.71 (m/s)/kHz, P < 0.05). The R-PTS was lower in the group with younger age (P < 0.05). Pearson correlation analysis showed that SWE_R of carotid artery was positively correlated with the parameters of tensile stress, R-PTS, R-MTS, L-PTS and L-MTS(r = 0.218, r = 0.359, r = 0.209 and r = 0.369, respectively, P < 0.05). However, SWD_R of carotid arteries was not significantly associated with TS.

Conclusion

Ultrasonic shear wave imaging could be used to quantitatively assess carotid viscoelasticity. The carotid TS was related to its elasticity while little related to its viscosity, suggesting that mechanical properties of the arterial wall might be better revealed.

Trial registration

Date of our trial registration: 2018-06-11. Registered with the official website of China Clinical Trial Registration Center (ChiCTR1800016590)

Correlating Carotid Intima-Media Thickness With Lipid Profile: Does It Improve Sonographic Diagnosis of Subclinical Atherosclerosis?

Objective. The purpose of this prospective study was to ascertain if lipid profile parameters could serve as predictors of carotid intima-media thickness (CIMT), which, when combined, may improve the sensitivity of sonographic CIMT measurement in the diagnosis of subclinical atherosclerotic changes. Methods. The lipid profiles and CIMT of 181 subjects without cardiovascular risk factors were measured at the internal, external, common, and bulbar segments. Results. The mean CIMT values obtained were 0.620 ± 0.055 cm for men and 0.575 ± 0.051 cm for women, and the η2 values (η2 < 0.04) were used as a measure of association. Across all segments of both carotid arteries, lipid profiles were significantly and moderately associated with but not predictive of CIMT (fasting blood sugar, total cholesterol, and low-density lipoprotein: η2 = 0.99–0.24). Conclusions. Although lipid profiles were moderately associated with CIMT, they are not significant predictors; hence, combining them with CIMT does not improve the diagnostic sensitivity of sonography in atherosclerosis screening.

Obesity and carotid artery remodeling

BACKGROUND/OBJECTIVE

The present study tested the hypothesis that obesity-related changes in carotid intima-media thickness (IMT) might represent not only preclinical atherosclerosis but an adaptive remodeling meant to preserve circumferential wall stress (CWS) in altered hemodynamic conditions characterized by body size-dependent increase in stroke volume (SV) and blood pressure (BP).

SUBJECTS/METHODS

Common carotid artery (CCA) luminal diameter (LD), IMT and CWS were measured in three different populations in order to study: (A) cross-sectional associations between SV, BP, anthropometric parameters and CCA LD (266 healthy subjects with wide range of body weight (24-159 kg)); (B) longitudinal associations between CCA LD and 3-year IMT progression rate (ΔIMT; 571 healthy non-obese subjects without increased cardiovascular (CV) risk); (C) the impact of obesity on CCA geometry and CWS (88 obese subjects without CV complications and 88 non-obese subjects matched for gender and age).

RESULTS

CCA LD was independently associated with SV that was determined by body size. In the longitudinal study, baseline LD was an independent determinant of ΔIMT, and ΔIMT of subjects in the highest LD quartile was significantly higher (28±3 μm) as compared with those in the lower quartiles (8±3, 16±4 and 16±3 μm, P=0.001, P<0.05 and P=0.01, respectively). In addition, CCA CWS decreased during the observational period in the highest LD quartile (from 54.2±8.6 to 51.6±7.4 kPa, P<0.0001). As compared with gender- and age-matched lean individuals, obese subjects had highly increased CCA LD and BP (P<0.0001 for both), but only slightly higher CWS (P=0.05) due to a significant increase in IMT (P=0.005 after adjustment for confounders).

CONCLUSIONS

Our findings suggest that in obese subjects, the CCA wall thickens to compensate the luminal enlargement caused by body size-induced increase in SV, and therefore, to normalize the wall stress. CCA diameter in obesity could represent an additional biomarker, depicting the impact of altered hemodynamics on arterial wall.

Carotid intima-media thickness and plaque in cardiovascular risk assessment

Carotid intima-media thickness (CIMT) has been shown to predict cardiovascular (CV) risk in multiple large studies. Careful evaluation of CIMT studies reveals discrepancies in the comprehensiveness with which CIMT is assessed-the number of carotid segments evaluated (common carotid artery [CCA], internal carotid artery [ICA], or the carotid bulb), the type of measurements made (mean or maximum of single measurements, mean of the mean, or mean of the maximum for multiple measurements), the number of imaging angles used, whether plaques were included in the intima-media thickness (IMT) measurement, the report of adjusted or unadjusted models, risk association versus risk prediction, and the arbitrary cutoff points for CIMT and for plaque to predict risk. Measuring the far wall of the CCA was shown to be the least variable method for assessing IMT. However, meta-analyses suggest that CCA-IMT alone only minimally improves predictive power beyond traditional risk factors, whereas inclusion of the carotid bulb and ICA-IMT improves prediction of both cardiac risk and stroke risk. Carotid plaque appears to be a more powerful predictor of CV risk compared with CIMT alone. Quantitative measures of plaques such as plaque number, plaque thickness, plaque area, and 3-dimensional assessment of plaque volume appear to be progressively more sensitive in predicting CV risk than mere assessment of plaque presence. Limited data show that plaque characteristics including plaque vascularity may improve CV disease risk stratification further. IMT measurement at the CCA, carotid bulb, and ICA that allows inclusion of plaque in the IMT measurement or CCA-IMT measurement along with plaque assessment in all carotid segments is emerging as the focus of carotid artery ultrasound imaging for CV risk prediction.

Relation of carotid artery diameter with cardiac geometry and mechanics in heart failure with preserved ejection fraction

BACKGROUND

Central artery dilation and remodeling are associated with higher heart failure and cardiovascular risks. However, data regarding carotid artery diameter from hypertension to heart failure have remained elusive. We sought to investigate this issue by examining the association between carotid artery diameter and surrogates of ventricular dysfunction.

METHODS AND RESULTS

Two hundred thirteen consecutive patients including 49 with heart failure and preserved ejection fraction (HFpEF), 116 with hypertension, and an additional 48 healthy participants underwent comprehensive echocardiography and tissue Doppler imaging. Ultrasonography of the common carotid arteries was performed for measurement of intima-media thickness and diameter (CCAD). Cardiac mechanics, including LV twist, were assessed by novel speckle-tracking software. A substantial graded enlargement of CCAD was observed across all 3 groups (6.8 ± 0.6, 7.7 ± 0.73, and 8.7 ± 0.95 mm for normal, hypertension, and HFpEF groups, respectively; ANOVA P<0.001) and correlated with serum brain natriuretic peptide level (R(2)=0.31, P<0.001). Multivariable models showed that CCAD was associated with increased LV mass, LV mass-to-volume ratio (β-coefficient=10.9 and 0.11, both P<0.001), reduced LV longitudinal and radial strain (β-coeffficient=0.81 and -3.1, both P<0.05), and twist (β-coefficient=-0.84, P<0.05). CCAD set at 8.07 mm as a cut-off had a 77.6% sensitivity, 82.3% specificity, and area under the receiver operating characteristic curves (AUROC) of 0.86 (95% CI 0.80 to 0.92) in discriminating HFpEF. In addition, CCAD superimposed on myocardial deformation significantly expanded AUROC (for longitudinal strain, from 0.84 to 0.90, P of ΔAUROC=0.02) in heart failure discrimination models.

CONCLUSIONS

Increased carotid artery diameter is associated with worse LV geometry, higher brain natriuretic peptide level, and reduced contractile mechanics in individuals with HFpEF.

Carotid circumferential wall stress homeostasis in early remodeling: theoretical approach and clinical application

PURPOSE

To assess the influence of cardiovascular risk factors on arterial wall growth and the remodeling process.

METHODS

In a theoretical part, we used a well-established relationship linking the rate of thickening of the arterial wall to the circumferential wall stress (CWS) increase. In a clinical part, we measured the intima-media thickness (IMT) in 166 subjects with increased cardiovascular risk score but no treatment for hypertension or hypercholesterolemia, no diabetes, and no cardiovascular disease. Far wall IMT and lumen diameter were measured along the right carotid artery by high-resolution ultrasonography and computerized image analysis.

RESULTS

A decreasing linear relationship between IMT and CWS was deduced from the theoretical model, implying that an increase in CWS would result in an IMT increase, and that the higher the IMT-CWS slope, the higher the thickening response. Subjects with advanced age, renal insufficiency, high 10-year Framingham risk, carotid atherosclerosis, and advanced atherosclerosis at other sites had sharper IMT-CWS slope (p < 0.05), in agreement with the homeostasis of CWS hypothesis.

CONCLUSIONS

The IMT increase responding to a CWS increase was greater in high-risk patients.

Clustering of metabolic syndrome traits is associated with maladaptive carotid remodeling and stiffening: a 6-year longitudinal study

Maladaptive arterial remodeling may constitute a mechanism underlying the risk of stroke in individuals with the metabolic syndrome (MetS), but evidence supporting this contention derives from cross-sectional studies only. We, therefore, investigated, in apparently healthy adults, whether changes in MetS status between the ages of 36 and 42 years (never [n=207, reference group], incident [n=31], recovery [n=23], and persistent [n=32]) were associated with changes in carotid interadventitial diameter, lumen diameter, intima-media thickness, circumferential wall tension and stress, and Young's elastic modulus. All data analyses were adjusted for sex, height, and (changes in) age, lifestyle variables, low-density lipoprotein cholesterol, and use of antihypertensive medication. At baseline and as compared with the reference group, individuals with persistent MetS had significantly higher interadventitial diameter, circumferential wall tension, circumferential wall stress, and Young's elastic modulus but not intima-media thickness. In the course of follow-up, these individuals (versus reference group) displayed significantly steeper increases in intima-media thickness (0.011 versus 0.005 mm/y), which were accompanied by significantly steeper increases in interadventitial diameter (0.077 versus 0.032 mm/y) and lumen diameter (0.055 versus 0.023 mm/y) but not circumferential wall stress, which decreased (-0.34 versus 0.12 kPa/y). These findings suggest that increases in intima-media thickness in young adults with the MetS may primarily reflect an adaptive mechanism that attempts to restore local hemodynamic conditions to an equilibrium rather than atherosclerosis, per se. However, carotid adaptations did not restore circumferential wall stress to levels comparable with those of the reference group, and, therefore, outward remodeling was maladaptive. Importantly, individuals who recovered from the MetS restored carotid properties to levels comparable to the reference group, emphasizing the potential for reversibility.

Estimation of blood velocity, volumetric flow and wall shear rate using Doppler ultrasound

Commercial ultrasound systems can make a number of measurements related to haemodynamics which are relevant to clinical practice and to clinical research. These include maximum velocity, volumetric flow and wall shear rate. Using appropriate protocols, measurements can be made averaged over the cardiac cycle, or as a function of time through the cardiac cycle. Maximum velocity underpins most of these measurements. Maximum velocity is overestimated as a result of geometric spectral broadening, by typically up to 30%, but by much larger amounts as the angle approaches 90°. Though not used in clinical practice, a simple correction technique using a string phantom can substantially reduce these errors. For volumetric flow and wall shear rate, methods such as specialist multi-gate ultrasound systems, magnetic resonance imaging and image guided modelling are available. Before resorting to these more complex methods users might consider that, with care and attention to procedure, high quality information may be obtained using commercial ultrasound systems. Manufacturers could make more use of the colour flow image for quantification of velocity, and adopt vector Doppler techniques.