Application of speckle-tracking in the evaluation of carotid artery function in subjects with hypertension and diabetes

Integrating Ultrasound-Derived Carotid Artery Stiffness in the Assessment of Cardiovascular Risk

Historically, pulse wave velocity (PWV) has been used to measure vascular stiffness, but is limited in its utility when certain vascular disease states are present, such as aneurysm or iliac stenosis. PWV can therefore only provide reliable assessment of global vascular stiffness in limited vascular pathology. Speckle tracking is a method of post-hoc ultrasound image analysis that can measure vascular stiffness in a more comprehensive manner. Evidence from in vitro as well as in vivo studies has validated these techniques in the assessment of strain, distensibility, modulus, and stiffness index (β) in the carotid arterial system. Unfortunately, despite the well-established correlation between vascular stiffness and cardiovascular morbidity and mortality, standard vascular laboratory ultrasound protocols do not include stiffness assessment. Herein, we present evidence in favor of integrating speckle tracking into carotid artery duplex protocols to measure vascular stiffness that can be utilized in medical management to modulate cardiovascular risk.

Evaluation of common carotid artery in type 1 diabetes mellitus patients through speckle tracking carotid strain ultrasonography

PURPOSE

We aimed to evaluate the effectiveness of speckle tracking carotid strain (STCS) technique, which enables measurement of arterial stiffness and strain parameters, in the detection of early atherosclerotic findings in type 1 diabetes mellitus (T1DM).

METHODS

We prospectively enrolled 30 T1DM patients and 30 age- and sex-matched control participants with no history of cardiovascular disease. All study population underwent carotid ultrasonography. Radial and circumferential movement of the common carotid artery (CCA) in the transverse plane as the well as the radial movement of the CCA in the longitudinal plane were calculated automatically by using the STCS method. In addition, the strain (%), strain rate (per second), and peak circumferential and radial displacements (mm) were calculated. Arterial stiffness parameters, such as elastic modulus, distensibility, arterial compliance, and β-stiffness index, were calculated using the radial measurements. The mean value of the carotid intima media thickness (CIMT) was calculated semi-automatically for each CCA, in the longitudinal plane. We also analyzed the patients' overall body composition.

RESULTS

T1DM and control groups were compared in terms of strain and stiffness parameters and no statistically significant difference was found (p > 0.05). CIMT was higher in diabetic patients than in the control group (p = 0.039). In both groups, age was correlated with all arterial stiffness and strain parameters (p < 0.05). The duration of diabetes was also correlated with β-stiffness index, distensibility, and elastic modulus in the longitudinal plane (p < 0.05). In the diabetic group, abdominal fat ratio, whole body fat ratio, and fat mass were correlated with radial and circumferential displacement and strain parameters in transverse plane, and radial displacement in longitudinal plane (p < 0.05, for each). Diabetic patients were divided into subgroups according to the presence of nephropathy and dyslipidemia. Although no significant difference was found between the groups in terms of CIMT, patients with nephropathy had higher values for transverse and longitudinal elastic modulus, pulse-wave velocity, and longitudinal β-stiffness index, as well as lower values for longitudinal arterial compliance and distensibility, compared with patients without nephropathy (p < 0.05). Also, patients with dyslipidemia had higher longitudinal β-stiffness and elastic modulus values compared with patients without dyslipidemia (p < 0.05).

CONCLUSION

STCS ultrasonography is an effective, easy, and noninvasive method for evaluating the arterial elasticity. It may provide an early assessment of atherosclerosis in patients with T1DM, especially in the presence of nephropathy and dyslipidemia; thus, together with CIMT measurement, it may be used more frequently to detect subclinical damage and stratify atherosclerosis.

Biomechanical Properties of Common Carotid Arteries Assessed by Circumferential 2D Strain and β Stiffness Index in Patients With Ankylosing Spondylitis

OBJECTIVE

Ankylosing spondylitis (AS) is associated with an elevated risk of cardiovascular disease (CVD) related to atherosclerosis, preceded by arterial stiffness. We aimed to examine common carotid artery (CCA) biomechanical properties using ultrasound to calculate β stiffness index (indicating arterial stiffness) and, a more recently developed technique, 2-dimensional (2D) speckle tracking strain (indicating arterial motion and deformation, strain) to (1) compare with age- and sex-matched controls, and (2) analyze relationships between strain and stiffness with disease characteristics and traditional risk factors for CVD in patients with AS.

METHODS

In this cross-sectional study, a cohort of 149 patients with AS, mean age 55.3 ± 11.2 years, 102 (68.5%) men, and 146 (98%) HLA-B27-positive, were examined. Bilateral CCA were examined for circumferential 2D strain and β stiffness index. A subgroup of 46 patients was compared with 46 age- and sex-matched controls, both groups without hypertensive disease, diabetes, myocardial infarction, or stroke.

RESULTS

Mean bilateral circumferential 2D strain was lower in AS patients compared with controls (7.9 ± 2.6% vs 10.3 ± 1.9%, P < 0.001), whereas mean bilateral β stiffness index was higher (13.1 ± 1.7 mmHg/mm vs 12.3 ± 1.3 mmHg/mm, P = 0.02). In multivariable linear regression analyses, strain was associated with age, erythrocyte sedimentation rate, history of anterior uveitis, and treatment with conventional synthetic disease-modifying antirheumatic drugs (DMARD) and/or biological DMARD (R² 0.33), while stiffness was associated with age (R² 0.19).

CONCLUSION

Both CCA circumferential 2D strain and β stiffness index differed between patients with AS and controls. Strain was associated with AS-related factors and age, whereas only age was associated with stiffness, suggesting that the obtained results reflect different pathogenic vascular processes.

Carotid arterial mechanics as useful biomarker of extracellular matrix turnover and preserved ejection fraction heart failure

Aims

We aimed to investigate the functional alterations, diagnostic utilization, and prognostic implication of carotid arterial deformations in subjects with cardiovascular risk factors and heart failure (HF) with preserved ejection fraction (HFpEF).

Methods and results

Among 251 prospectively participants (mean age 66.0 ± 9.8 years, 65.7% female) in a single centre between December 2011 and September 2014, carotid artery deformations including circumferential strain (CCS)/strain rate and radial strain were analysed by two‐dimensional speckle tracking. We further related these carotid artery deformation indices to HF biomarkers and cardiac structure and function by echocardiography and explored their prognostic values. Significant reductions of CCS, circumferential strain rate, and circumferential radial strain were observed across control (n = 52), high risk (n = 147), and HFpEF (n = 52) (trend P ≤ 0.001). Aging, hypertension, HFpEF, and higher pulse rate showed independent associations with reduced CCS by stepwise multivariate regressions (all P < 0.05). Higher CCS was inversely associated with better cardiac remodelling and functional indices, and lower multiple HF biomarkers (all P ≤ 0.005). After adjustment, higher CCS was independently associated with better global ventricular longitudinal strain/early diastolic strain rate, lower matrix metalloproteinase‐2, and N‐terminal propeptide of procollagen type III levels (adjusted coef: −0.08 and −19.9, all P < 0.05). During a median follow‐up of 1406 days (interquartile range: 1342‑1720 days), CCS less than 3.28% as a cut‐off had markedly higher HF events [Harrell's C: 0.72, adjusted HR: 2.20 (95% confidence interval: 1.24, 3.16), P = 0.008]. CCS also showed significantly improved risk prediction for HF over global ventricular longitudinal strain (net reclassification index: 48%, P = 0.001; integrated discrimination improvement: 1.8%, P < 0.001).

Conclusions

Carotid artery deformations using two‐dimensional speckle‐tracking imaging showed novel mechanistic insights on functional arterial alterations reflecting coupled arterial‐ventricular pathophysiology. Utilization of such measure may further provide additive prognostic value to advanced myocardial functional assessment.

Magnetic resonance imaging based modeling of microvascular perfusion in patients with peripheral artery disease

Peripheral artery disease (PAD) is associated with an increased risk of adverse cardiovascular events, impaired lower extremity blood flow and microvascular perfusion abnormalities in the calf muscles which can be determined with contrast-enhanced magnetic resonance imaging (CE-MRI). We developed a computational model of the microvascular perfusion in the calf muscles. We included 20 patients (10 PAD, 10 controls) and utilized the geometry, mean signal intensity and arterial input functions from CE-MRI calf muscle perfusion scans. The model included the microvascular pressure (pv), outflow filtration coefficient (OFC), transfer rate constant (kt), porosity (φ), and the interstitial permeability (Ktissue). Parameters were fitted and the simulations were compared across PAD patients and controls. Intra-observer reproducibility of the simulated mean signal intensities was excellent (intraclass correlation coefficients >0.995). kt and Ktissue were higher in PAD patients compared with controls (4.72 interquartile range (IQR) 3.33, 5.56 vs. 2.47 IQR 2.10, 2.85; p = 0.003; and 3.68 IQR 3.18, 4.41 vs. 1.81 IQR 1.81, 1.81; p < 0.001). Conversely, porosity (φ) was lower in PAD patients compared with controls (0.52 IQR 0.49, 0.54 vs. 0.61 IQR 0.58, 0.64; p = 0.016). Porosity (φ) was correlated with the ankle brachial index (r = 0.64, p = 0.011). The proposed computational microvascular model is robust and reproducible, and essential model parameters differ significantly between PAD patients and controls.

3-D Strain Imaging of the Carotid Bifurcation: Methods and in-Human Feasibility

Atherosclerotic plaque development in the carotid artery bifurcation elevates the risk for stroke, which is often initiated by plaque rupture. The risk-to-rupture of a plaque is related to its composition. Two-dimensional non-invasive carotid elastography studies have found a correlation between wall strain and plaque composition. This study introduces a technique to perform non-invasive volumetric elastography in vivo. Three-dimensional ultrasound data of carotid artery bifurcations were acquired in four asymptomatic individuals using an electrocardiogram-triggered multislice acquisition device that scanned over a length of 35 mm (350 slices) using a linear transducer (L11-3, f_c = 9 MHz). For each slice, three-angle ultrasound plane wave data were acquired and beamformed. A correction for breathing-induced motion was applied to spatially align the slices, enabling 3-D cross-correlation-based compound displacement, distensibility and strain estimation. Distensibility values matched with previously published values, while the corresponding volumetric principal strain maps revealed locally elevated compressive and tensile strains. This study presents for the first time 3-D elastography of carotid arteries in vivo.

Usefulness of Carotid Arterial Strain Values for Evaluating the Arteriosclerosis

AIM

We investigated the clinical usefulness of carotid arterial strain and the strain rate for evaluating the progression of arteriosclerosis measured using a two-dimensional speckle-tracking method in carotid ultrasonography.

METHODS

We enrolled 259 participants (age: 64±12 years; men: 149; women: 110) in this retrospective analysis. The circumferential strain and the strain rate were measured in bilateral common carotid arteries, and the lowest values were used for the analyses. To assess the characteristics of strain and the strain rate, we investigated the associations between the strain values and gender, age, body mass index (BMI), blood pressure (BP), and the presence of hypertension, diabetes mellitus, and hyperlipidemia. We also examined the explanatory factors for the strain values using clinical parameters along with the intima-media thickness (IMT), the ankle brachial index (ABI), and the cardio-ankle vascular index (CAVI) as possible candidates. Finally, we investigated whether the strain values might be an independent predictor for vascular diseases using multivariate logistic regression analyses.

RESULTS

The carotid circumferential strain and the strain rate were significantly correlated with age, IMT, and the CAVI, but not with the BMI, BP, or ABI. Strain and the strain rates were lower in participants with hypertension or cerebrovascular disease and were selected as significant predictive factors for the presence of cerebrovascular diseases, together with diabetes and the CAVI.

CONCLUSIONS

Strain and the strain rate of carotid arteries, which could represent local arterial stiffness, might be associated with atherosclerosis and could possibly be used to predict cerebrovascular disease.

End-Stage Renal Disease Impairs the Multidirectional Movements of the Common Carotid Artery: Assessment Using Dimensional Speckle-Tracking Carotid Strain Ultrasonography

BACKGROUND

Arterial stiffening is a major contributing factor in the development of cardiovascular disease in patients with end-stage renal disease (ESRD). However, there is no gold standard for evaluating arterial stiffness. This study aimed to evaluate the newly developed speckle-tracking carotid strain imaging method in assessing arterial stiffness in patients with ESRD.

METHODS

In total, 85 patients with normal renal function (controls) and 36 with ESRD were enrolled in this single-center study. Carotid B-mode ultrasonography was performed for all patients. Arterial stiffness indices and strain parameters of the common carotid arteries were analyzed. Values were compared between the groups, and multivariate linear regression analysis was performed to assess the impact of ESRD on carotid strain.

RESULTS

There were no differences in the intima-media thickness, β stiffness index, and arterial compliance, but arterial distensibility was lower, and the elastic modulus and pulse wave velocity β (PWV) were higher among patients with ESRD (all p < 0.05), whether assessed in the longitudinal or transverse plane. Both longitudinal and transverse strain rates were reduced in patients with ESRD (all p < 0.05). In multivariate analyses, ESRD independently reduced both transverse radial strain and strain rate (all p < 0.05), and the transverse circumferential strain and strain rate (p < 0.05). However, all conventional aortic stiffness indices and longitudinal strain parameters were not associated with ESRD.

CONCLUSIONS

Speckle-tracking carotid strain ultrasonography was successfully performed in both normal subjects and patients with ESRD. Multidirectional carotid strain analyses may provide more value than conventional aortic stiffness indices for risk stratification in patients with ESRD.

Assessment of multidirectional movements of the common carotid artery in atherothrombotic stroke using dimensional speckle tracking carotid ultrasonography: A prospective, controlled cohort study

AIM

We aimed to explore the relevance of multidirectional movements of the common carotid artery in atherothrombotic stroke.

METHODS AND RESULTS

We prospectively enrolled 69 patients with atherothrombotic stroke (stroke group) and 69 age-matched and sex-matched controls (control group) who underwent carotid ultrasonography. Based on the speckle tracking technique, circumferential and radial movements of the common carotid artery were analyzed from transverse and longitudinal B-mode images of the common carotid artery. Peak longitudinal and radial displacements, strain, and strain rate were measured. Mean age of the overall population was 64 ± 11 years, and 57% (78 patients) were men. In the transverse image, circumferential strain was significantly lower in the stroke group than in the control group (5.6 ± 1.6 vs 4.2 ± 1.7, P < .001). In multivariate logistic regression analysis, circumferential strain was independently associated with stroke (odds ratio: 0.60, P = .001). Compared with conventional risk factors, as well as carotid intima-media thickness and carotid plaque, the addition of a strain parameter appeared to improve discrimination of a stroke event (area under the receiver operating characteristic curve: 0.65 and 0.75 vs 0.84, respectively; P < .05 for both).

CONCLUSIONS

Circumferential strain of the common carotid artery might serve as a novel surrogate marker of atherothrombotic stroke. Multidirectional strain imaging of the common carotid artery may provide more information than conventional carotid ultrasonography and identify clinical risk factors for risk stratification of an acute stroke event.

Circumferential strain of carotid arteries does not differ between patients with advanced coronary artery disease and group without coronary stenoses

PURPOSE

Speckle tracking echocardiography is widely used for the analysis of myocardial function. Recently, circumferential strain (CS) of carotid arteries was postulated as novel indicator of vascular function. Our aim was to characterize and compare CS of carotid arteries in patients with advanced coronary artery disease and controls without significant coronary stenoses.

PATIENTS/METHODS

We compared CS of both common carotid arteries (CCA) in the 25 patients with three-vessel coronary artery disease (3VD) (mean age 69±9 years, 9 male) and in 16 age-matched subjects without significant coronary lesions (C) (69±8 years, 7 male). Additionally in 11 patients we estimated pulse wave velocity (PWV) and assessed the correlation between PWV and CS. Short-axis images of arteries were acquired for strain analysis with linear probe of echocardiograph. The assessment of CS was performed off-line by two observers.

RESULTS

The intraobserver variability for the CS (coefficient of variation) were 4.9 and 5.4% for left and right CCA and interobserver variability were 11.7% and 12.5%, respectively. The mean CS for left and right CCA did not differ between compared groups. We did not find correlation between CS strain and PWV. The only difference was related to the more prevalent plaque presence and thicker intima-media complex (IMT) in 3VD (p=0.0039 for IMT of left CCA and p=0.016 for IMT of right CCA).

CONCLUSIONS

The global CS of CCA, contrary to IMT, did not allow for differentiation between 3VD and C subjects. Despite good feasibility and concordance of CS measurements its clinical significance remains to be established.

Calf muscle perfusion as measured with magnetic resonance imaging to assess peripheral arterial disease

We hypothesized that skeletal muscle perfusion is impaired in peripheral arterial disease (PAD) patients compared to healthy controls and that perfusion patterns exhibit marked differences across five leg muscle compartments including the anterior muscle group (AM), lateral muscle group (LM), deep posterior muscle group (DM), soleus (SM), and the gastrocnemius muscle (GM). A total of 40 individuals (26 PAD patients and 14 healthy controls) underwent contrast-enhanced magnetic resonance imaging (CE-MRI) utilizing a reactive hyperemia protocol. Muscle perfusion maps were developed for AM, LM, DM, SM, and GM. Perfusion maps were analyzed over the course of 2 min, starting at local pre-contrast arrival, to study early-to-intermediate gadolinium enhancement. PAD patients had a higher fraction of hypointense voxels at pre-contrast arrival for all five muscle compartments compared with healthy controls (p < 0.0005). Among PAD patients, the fraction of hypointense voxels of the AM, LM, and GM were inversely correlated with the estimated glomerular filtration rate (eGFR; r = -0.509, p = 0.008; r = -0.441, p = 0.024; and r = -0.431, p = 0.028, respectively). CE-MRI-based skeletal leg muscle perfusion is markedly reduced in PAD patients compared with healthy controls and shows heterogeneous patterns across calf muscle compartments.

Postprandial effects on arterial stiffness parameters in healthy young adults

Postprandial lipemia has been associated with acute endothelial dysfunction. Endothelial dysfunction, in turn, is associated with increased arterial stiffness. However, the relationship between postprandial lipemia and acute changes in arterial stiffness has not been extensively investigated. Therefore, we conducted a pilot study on the effects of postprandial lipemia on arterial stiffness in 19 healthy young adults before and after consumption of a high-fat mixed meal. Arterial stiffness was assessed locally with echo-tracking carotid arterial strain (CAS) and globally with carotid–femoral pulse wave velocity (PWV). As assessed by these two benchmark parameters, arterial stiffness did not differ significantly postprandially. However, the arterial distension period (ADP) was significantly lower 2 hours after mixed meal ingestion. In addition, slopes of carotid artery area (CAA) curves were significantly steeper postprandially. Therefore, we concluded that ADP may be a more sensitive marker of arterial stiffness in healthy young adults when compared to PWV and CAS.