Properties Of Arterial Wall Research Articles

Smoking and diabetes attenuate beneficial effects of PSCK9 inhibitors on arterial wall properties in patients with very high lipoprotein (a) levels

Background and aimsElevated lipoprotein (a) (Lp(a)) and low-density lipoprotein cholesterol levels (LDL-C) are significant residual risk factors for cardiovascular events. Treatment with protein convertase subtilisin kexin type 9 (PCSK9) inhibitors reduces the levels of both. Less is known about effects of PCSK9 inhibitors on functional and morphological properties of the arterial wall. The aim of the present study was to determine whether other factors besides decreased LDL-C and Lp(a) are associated with functional (flow-mediated dilation [FMD]) and morphological (carotid intima-media thickness [c-IMT], pulse-wave velocity [PWV]) changes of the arterial wall properties in patients with coronary artery disease (CAD) treated with alirocumab and evolocumab. MethodsOne hundred patients with CAD after myocardial infarction before 55 years and with high Lp(a) were randomised to lipid-lowering therapies without PCSK9 inhibitors (control; N = 31), or with alirocumab 150 mg SC (N = 35) or evolocumab 140 mg SC (N = 34), every 2 weeks. All patients underwent blood sampling for biochemical analyses and ultrasound measurements for FMD, c-IMT and PWV. ResultsThere were no significant changes in FMD for the control (10.7% ± 6.6%–11.1% ± 4.4%, p = 0.716) and alirocumab (10.7% ± 5.9%–11.2% ± 5.3%, p = 0.547) groups, while evolocumab promoted significant increase (11.2% ± 6.8%–14.1% ± 6.6%, p < 0.0001). Only in non-smokers and non-diabetics significant improvements in FMD (p < 0.0001) after treatment with PCSK9 inhibitors were observed. ConclusionThese data show that for patients with CAD and high Lp(a) levels, beneficial effects of PCSK9 inhibitors on the arterial wall properties can be attenuated by specific risk factors, such as smoking and diabetes.

LPA genotypes and haplotypes influence lipoprotein(a) levels but not arterial wall properties, in stable post-coronary event patients with very high lipoprotein(a) levels

Background and Aims: Lipoprotein (a) [Lp(a)] levels are an independent risk factor for coronary artery disease. Two single nucleotide polymorphisms (rs1045587, rs10455872) and KIV-2 repeats in the gene encoding Lp(a) (LPA) are strongly associated with increased Lp(a) levels and coronary artery disease. The aim was to initially investigate whether in stable patients following myocardial infarction and with very high Lp(a) levels these genetic variants are associated with increased Lp(a) levels. We then also investigated the functional and morphological characteristics of the arterial wall in these patients.

The interplay of cardiac dysfunctions and hemodynamic impairments during the progression of myocardial infarction in male rats

Myocardial infarction (MI) can induce heart failure with reduced ejection fraction (HFrEF). Systemic circulation is of importance to interact with MI-induced HFrEF. Hence, we studied the changes of myofiber stresses and peripheral hemodynamics during the progression from MI to HFrEF. MI was induced in Wistar male rats by the coronary artery ligation surgery. Physiological and hemodynamic measurements were carried out in the LV and peripheral arteries at postoperative 3 and 6 weeks, based on which LV myofiber stresses were computed and peripheral hemodynamic analysis was demonstrated. This study showed that MI significantly impaired cardiac functions and peripheral hemodynamics and altered the corresponding histological properties of cardiac wall and peripheral arterial wall, which deteriorated with time after operation. In summary, the interplay of cardiac dysfunctions and hemodynamic impairments accelerates the progression of MI-induced HF.

In vivo Evidence of Arterial Dynamic Properties Alteration in Atherosclerotic Rabbit

Objectives: Atherosclerosis severely damages the arterial wall. The aim of this study was to assess in vivo, for the first time, arterial dynamic properties, reactivity, and stiffness in atherosclerotic (ATH) rabbits. Methods: The rabbits were fed with 0.3% cholesterol diet. Femoral artery (FA) or abdominal aorta (AA) diameter was recorded by echotracking, together with blood pressure. Arterial reactivity after local administration of agents and stiffness were measured as diameter or pulsatile diameter changes. Results: FA dilation induced by acetylcholine was reduced in the function of diet duration (9–65 weeks). With mid-term diet duration (35–45 weeks), the dilation to nitroprusside was greatly reduced; the constriction to norepinephrine was reduced but not that to serotonin, thromboxane agonist, or angiotensin II. After 17- and 28-week diet AA and FA stiffness were increased while distensibility was reduced. Arterial stiffness measured by regional pulse wave velocity was unaltered. We observed that after 28-week diet, FA exhibited a stiffened wall at the plaque level and higher distensibility at the upstream site. Discussion/Conclusion: Arterial reactivity and compliance were greatly modified by atherosclerosis, at various degrees dependent on diet duration. ATH rabbit is therefore a suitable model for in vivo investigations of treatments targeting dynamic properties of arterial wall.

Smoking and Diabetes Attenuate Beneficial Effects of PSCK9 Inhibitors on Arterial Wall Properties in Patients with Very High Lipoprotein (a) Levels

Smoking and Diabetes Attenuate Beneficial Effects of PSCK9 Inhibitors on Arterial Wall Properties in Patients with Very High Lipoprotein (a) Levels

LPA Genotypes and Haplotypes Are Associated with Lipoprotein(a) Levels but Not Arterial Wall Properties in Stable Post-Coronary Event Patients with Very High Lipoprotein(a) Levels.

Lipoprotein(a) [Lp(a)] levels are an independent risk factor for coronary artery disease (CAD). Two single-nucleotide polymorphisms (rs10455872, rs3798220) and number of KIV-2 repeats in the gene encoding Lp(a) (LPA) are associated with Lp(a) and CAD. Our aim was to investigate whether in patients with stable CAD and high Lp(a) levels these genetic variants are associated with increased Lp(a) and arterial wall properties. Blood samples underwent biochemical and genetic analyses. Ultrasound measurements for the functional and morphological properties of arterial wall were performed. Genotypes of rs10455872 and haplotypes AT and GT showed significant association with Lp(a) levels. Patients with GG showed significantly higher Lp(a) levels compared with those with AG genotype (2180 vs. 1391 mg/L, p = 0.045). Patients with no AT haplotype had significantly higher Lp(a) compared to carriers of one AT haplotype (2158 vs. 1478 mg/L, p = 0.023) or two AT haplotypes (2158 vs. 1487 mg/L, p = 0.044). There were no significant associations with the properties of the arterial wall. Lp(a) levels significantly correlated also with number of KIV-2 repeats (r = −0.601; p < 0.0001). In our patients, these two LPA polymorphisms and number of KIV-2 repeats are associated with Lp(a), but not arterial wall properties.

Ascending aortic aneurysm haemodynamics are associated with aortic wall biomechanical properties.

The effect of aortic haemodynamics on arterial wall properties in ascending thoracic aortic aneurysms (ATAAs) is not well understood. We aim to delineate the relationship between shear forces along the aortic wall and loco-regional biomechanical properties associated with the risk of aortic dissection. Five patients with ATAA underwent preoperative magnetic resonance angiogram and four-dimensional magnetic resonance imaging. From these scans, haemodynamic models were constructed to estimate maximum wall shear stress (WSS), maximum time-averaged WSS, average oscillating shear index and average relative residence time. Fourteen resected aortic samples from these patients underwent bi-axial tensile testing to determine energy loss (ΔUL) and elastic modulus (E10) in the longitudinal (ΔULlong,E10long) and circumferential (ΔULcirc,E10circ)directions and the anisotropic index (AI)for each parameter. Nine resected aortic samples underwent peel testing to determine the delamination strength (Sd). Haemodynamic indices were then correlated to the biomechanical properties. A positive correlation was found between maximum WSS and ΔULlongrs=0.75,P=0.002 and AIΔUL (rs=0.68,P=0.01). Increasing maximum time-averaged WSS was found to be associated with increasing ΔULlong (rs=0.73,P=0.003) and AIΔUL (rs=0.62,P=0.02).Average oscillating shear index positively correlated with Sd (rs=0.73,P=0.04). No significant relationship was found between any haemodynamic index and E10, or between relative residence time and any biomechanical property. Shear forces at the wall of ATAAs are associated with local degradation of arterial wall viscoelastic hysteresis (ΔUL) and delamination strength, a surrogate for aortic dissection. Haemodynamic indices may provide insights into aortic wall integrity, ultimately leading to novel metrics for assessing risks associated with ATAAs.

Comparison of a histology based multi layer artery model to its simplified axisymmetric model.

Abstract Arteries are vessel structures that serve vital function of transportation of blood to different parts of the body. Researchers have experimented with some approaches to model the arterial behaviour and to analyse its biomechanical properties. To analyse the in-vivo arterial properties, at Furtwangen University an inflatable sensoractuator system is being developed, which provides the basis for a decision support system for vascular surgeons. The capabilities of this sensor shall be evaluated in simulations which requires appropriate modelling of the arteries. The inverse problem, i.e. how to efficiently identify arterial wall properties from sensor readings is targeted. A histology motivated 3D artery model was implemented in FEM using COMSOL (v5.5). The geometry of one model was based on a cross section of a real artery. The second model was axisymmetric and of equal dimensions with respect to volume, layer thickness etc. A biomechanical pressure-stretch analysis was performed applying an inflating pressure inside the walls of the vessels. Stretch in different areas of the first model was evaluated and the circumferential strain was compared to the axisymmetric model. The results show variation of strains within the segments of the first model of upto 10 percent. In addition, its outer wall circumferential stretch was found to be 10 percent lower compared to the axisymmetric setup. This comparison sheds light upon whether a simplification of arterial models is possible, without loss of accuracy in the context of the novel sensor evaluation. It provides useful information whether e.g. standardizing vessel structures to axisymmetric models will still provide results within allowable tolerance limits. Simulations proved useful to evaluate different vessel model formulations in the context of arterial diagnostics.

Image processing to delineate the boundaries of peripheral arterial walls

Abstract The analysis of the arterial wall properties is vital in the prediction of stroke events and arterial hypertension in humans. Numerous researchers have experimented with several approaches to model arterial vessels and to analyse their biomechanical behaviour for many years now. Our study is focussed on image processing of peripheral arterial cross sections to detect and isolate the distinct layers. These boundaries will enable the creation of FEM models for further analysis of arterial wall properties. In a clinical setting, it facilitates doctors to identify the optimum pressure that can be applied to the artery for the treatment of stenosis without damaging the morphology of the blood vessels. This paper aims at distinguishing the various layers of arterial walls from images by minimizing human intervention. Cross section images of arteries from various sources were collected[10][11]. The boundaries from the image were obtained using image processing techniques of MATLAB(R2021a). The approach identified was to convert the input RGB images to grayscale, thresholding and applying morphological operators to delineate the Intima, Media, and Adventitia. These regions of interests (ROI) were then superimposed to generate an image with differentiated boundaries and void of unnecessary noise and inhomogeneity. This approach gave us an insight of the differences in various methods of boundary detection and to infer the optimum approach for accurate demarcation of boundaries of the three layers of arterial walls. It paves a pathway for forward modelling and to perform detailed FEM analysis in in-vitro diagnostics. In a nutshell, it was observed that the edge detection procedure implemented could be used for healthy and stenotic arteries. Further studies must be conducted to test the efficiency across a wide range of images and hence generalise its usage. Upon satisfactory boundary detection, forward modelling could be performed using the identified geometric forms.

Effect of linear and Mooney\u2013Rivlin material model on carotid artery hemodynamics

Atherosclerosis is one of the most common cardiovascular diseases leading to high morbidity. The study of arterial dynamics using fluid–structure interaction (FSI) technique by taking into account the physiology of flow, the critical hemodynamic parameters can be determined which plays a crucial role in predictive medicine. Due to advances in the computational facilities, coupled field analysis such as FSI can facilitate understanding of the mechanics of stenosis progression and its early diagnosis. In this study a two-way FSI analysis is carried out using modified Navier–Stokes equations as the governing equations of blood flow for determining hemodynamic parameters. The arterial wall has been described at different linear elastic modulus and compared with hyperelastic Mooney–Rivlin model to evaluate the effect of different arterial stiffness on hemodynamics. The Mooney–Rivlin model predicts flow reduction with the severe backflow at arterial bifurcation resulting in decreased shear stress and oscillatory behavior. Furthermore, these findings may be used in understanding the advantages and disadvantages of using hyperelastic artery model in numerical simulations to better understand and predict the variable that causes cardiovascular diseases and as a diagnostic tool. In the present study, variation due to change in arterial wall properties such as linear elastic and Mooney Rivlin hyperelastic and its influence on hemodynamics are investigated.

Arterial stiffening acts synergistically with APOE genotype and AD biomarker status to influence memory in older adults without dementia

BackgroundArterial stiffening has emerged as an important risk factor for Alzheimer’s disease (AD) and related dementias. Carotid-femoral pulse wave velocity has been proposed as a non-invasive and reproducible method to assess arterial stiffness. However, the association of pulse wave velocity with performance across multiple cognitive domains as well as interactions with in vivo AD biomarkers and apolipoprotein E (APOE) genotype has received limited study.MethodWe studied 193 older adult volunteers (167 with normal cognition and 26 with mild cognitive impairment) who underwent comprehensive medical and neuropsychological evaluation at the University of California, San Diego Alzheimer’s Disease Research Center. Cerebrospinal fluid (CSF) biomarkers were available on 123 participants (63%). Linear models examined whether pulse wave velocity significantly interacted with APOE ε4 status and CSF AD biomarker positivity (based on the ratio of total tau over beta-amyloid [tau/Aβ42]) on memory, language, executive functioning, attention, and visuospatial abilities.ResultsAfter adjusting for demographic characteristics and vascular risk burden, across the entire sample, pulse wave velocity was associated with poorer executive functioning but not the performance in the other cognitive domains. When the modifying effects of AD genetic risk and CSF AD biomarkers were considered, pulse wave velocity interacted with APOE genotype and CSF tau/Aβ ratio such that a stronger association between elevated pulse wave velocity and poorer memory performance was found among those positive for CSF and genetic AD markers. There were no significant interaction effects for non-memory cognitive domains.ConclusionThe findings suggest that pulse wave velocity, a non-invasive method to assess arterial wall properties, may be a useful marker of risk for cognitive decline, particularly among individuals who are APOE ε4 carriers or CSF AD biomarke0r-positive.

Influence of long-term controlled therapeutic exercises on blood pressure profile parameters, elastic properties of arterial wall, metabolic and mineral indices in females with arterial hypertension

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Tyumen Cardiology Research Center, Tomsk National Research Medical Center, Russian Academy of Sciences, Tomsk, Russia Objective To study the role of therapeutic exercises (TE) in the correction of blood pressure, stiffness of the vascular wall, metabolic indices of body structure (volume, mass, area of visceral fat) and bone mineral metabolism in postmenopausal hypertensive patients. Methods. The study included 138 patients (mean age was 58.32 ± 7.61 years). All patients are divided into 3 groups. The first control group is 20 women without arterial hypertension and menopausе. The second group consisted of 58 patients with arterial hypertension (AH) and postmenopause who was not undergone complex of TE and the 3rd group - 60 women with AH and postmenopause who was undergone TE complex. Patients of all groups were examined in dynamics: at the starting point of the study and in 12 months after, ambulatory monitoring of blood pressure; sphygmography; densitometry and test for serum biochemistry parameters of blood samples, including sex hormones, vitamin D. Results. In the course of the study, blood pressure, vascular wall stiffness parameters, metabolic indices of body structure and disorder parameters of bone mineral metabolism were comparable in group 2 and 3 against the background of significantly reduced levels of sex hormones. Multidirectional correlation relationships between the studied parameters are revealed. The basic therapy in combination with therapeutic exercises led to a significant decrease in blood pressure and metabolic indices of body structure (p&amp;lt;.001) and to a persistent tendency of decrease the pulse wave velocity and increase of bone mineral metabolism in gr.3. Conclusion. The result of the study indicates that the exercise therapy complex used in the form of regular classes can be recommended for implementation in clinical practice with the aim of comprehensively affecting the patient’s body and developing personalized treatment tactics for postmenopausal women with hypertension.

Pulse wave velocity is decreased in acromegaly compared to non-acromegaly study participants with similar cardiovascular risk profile

ObjectiveAcromegaly patients were reported to have an increased arterial stiffness that could contribute to the frequent cardiovascular complications in this population. The chronic excess of GH and IGF-1 may lead to arterial stiffening via different mechanisms, including hypertension, impaired glucose tolerance and dyslipidemia, however, it is not known whether the activation of GH/IGF-1 axis might influence arterial stiffening independently of cardiovascular risk factors. The objective of this prospective case-control study was to compare arterial stiffness assessed with pulse-wave velocity (PWV) in acromegaly versus non-acromegaly group with similar cardiovascular risk profile. DesignThis prospective case-control study included 27 patients with active acromegaly, who underwent the assessment of clinical, physiological, biochemical parameters and the evaluation of PWV with applanation tonometry. We used “The epidemiology of cardiovascular disease in different regions of the Russian Federation” study database (n = 522) to establish a non-acromegaly control group with similar cardiovascular risk profile (n = 54). Non-acromegaly control participants underwent the same assessment as acromegaly patients except for the measurement of serum GH and IGF-1 levels. We compared PWV in acromegaly patients to the general non-acromegaly cohort and its subset, matched with acromegaly patients for cardiovascular risk factors. We also investigated the associations of PWV with clinical, physiological and biochemical parameters in acromegaly and non-acromegaly group using correlation and regression analysis with adjustment for age and sex. ResultsAcromegaly patients had lower PWV (6.70 (5.75–7.65) m/s) compared to unmatched non-acromegaly control cohort (7.50 (6.70–8.57) m/s, p = 0.01) and to the non-acromegaly control group matched for cardiovascular risk factors (7.45 (6.73–8.60), p < 0.01). In non-acromegaly control group PWV was associated with BMI (ρ = 0.40, p < 0.01; β = 0.09, p < 0.01), obesity (r = 0.46, p < 0.01; β = 1.36, p < 0.01), systolic blood pressure (ρ = 0.60, p < 0.01; β = 0.05, p < 0.01), diastolic blood pressure (ρ = 0.62, p < 0.01; β = 0.07, p < 0.01), triglycerides (ρ = 0.55, p < 0.01; β = 0.58, p = 0.04), glucose (ρ = 0.54, p < 0.01; β = 0.70, p < 0.01) and diabetes (r = 0.40, p < 0.01; β = 1.10, p = 0.03), while in acromegaly group PWV was associated with IGF-1 expressed in mcg/ml (ρ = −0.49, p ≤0.01; β = −0.002, p ≤0.01) and in percentage of the upper limit of the normal (ρ = −0.47, p = 0.01; β = −0.005, p ≤0.01) as well as with diuretics treatment (β = −1.17, p = 0.03). ConclusionsPWV is decreased in acromegaly patients compared to non-acromegaly control participants with similar cardiovascular risk profile. Future studies need to explore the role of GH/IGF-1 axis in the regulation of arterial wall properties and the reliability of PWV as a prognostic marker of cardiovascular complications in acromegaly.

Numerical Investigation of the Dynamical Behavior of a Fluid-Filled Microparticle Suspended in Human Arteriole.

The study of artificial microparticles (capsules and vesicles) has gained a growing interest with the emergence of bio-engineering. One of their promoting applications is their use as therapeutic vectors for drug delivery, when capsules and vesicles release their capacity in a targeted environment. The dynamic behavior of capsules and vesicles in confined or unbounded flows was widely studied in the literature and their mechanical response was truthfully described using constitutive laws with good agreement with experiences. However, in a context of biological application, to our knowledge, none of published studies investigating the mechanical response of deformable microparticle took into account the real physiological conditions: the rheological properties of blood such as carrying fluid and the mechanical properties of blood vessels. In this paper, we consider a hyperelastic microparticle suspended in human arteriole. We investigate the deformation of the microparticle resulting from its interaction with blood flow and the arteriolar wall using various capillary numbers and respecting physiological properties of blood and arterial wall. The influence of the blood viscosity model (Newtonian versus shear thinning) is investigated and a comparison with a rigid microchannel and a muscle-embedded arteriole is carried out. The fluid structure interaction (FSI) problem is solved using arbitrary Lagrangian Eulerian (ALE) method. Our simulations have revealed that the arteriolar wall distensibility deeply influences both the deformation and velocity of the microparticle: the deformation strongly increases while the velocity decreases in comparison to an infinitely rigid wall. In the context of therapeutic procedure of targeted drug-delivery, a particular attention should be addressed to these observations, in particular for their implication in the burst mechanism.

Lipoprotein-associated phospholipase A2 levels, endothelial dysfunction and arterial stiffness in patients with stable coronary artery disease

BackgroundLipoprotein-associated Phospholipase A2 (Lp-PLA2), can exert proinflammatory as well as proatherogenic properties on the vascular wall. The current study sought to evaluate the influence of high Lp-PLA2 levels on indices of arterial wall properties in patients with stable coronary artery disease (CAD).MethodsThree hundred seventy-four consecutive patients with stable CAD (mean age 61 ± 11 years, 89% males) were enrolled in this single-center cross-sectional study. Flow-mediated dilation (FMD) was used to assess endothelial function and augmentation index (AIx) of the central aortic pressure was used to assess reflected waves. ELISA was used to determine Lp-PLA2 serum levels.ResultsAfter dividing the participants in 3 equal groups based on the tertiles of circulating Lp-PLA2 values, no significant differences were demonstrated between those in the 3rd tertile with Lp-PLA2 values > 138 μg/L, in the 2nd tertile with Lp-PLA2 values between 101 and 138 μg/L and in the 1st tertile (Lp-PLA2 values < 101 μg/L) regarding age, male gender, smoking habits, family history of CAD or history of a previous myocardial infarction, diabetes mellitus, arterial hypertension, hyperlipidemia, duration of CAD and treatment with relevant medication. Importantly, subjects with Lp-PLA2 values in the highest tertile, had significantly reduced FMD values compared to the middle and lower tertile (4.43 ± 2.37% vs. 4.61 ± 1.97% vs. 5.20 ± 2.52% respectively, P = 0.03). Patients in the highest tertile of Lp-PLA2 values had significantly higher AIx values (24.65 ± 8.69% vs. 23.33 ± 9.65%, P = 0.03), in comparison to the lowest tertile, with Lp-PLA2 values < 101 μg/L. A linear regression analysis showed that Lp-PLA2 values > 138 μg/L negatively correlated to FMD [b = − 0.45 (95% CI: − 0.79 – -0.11), P = 0.01] and AIx values [b = 1.81 (95% CI: 0.57–3.05), P < 0.001] independently of cofounders like gender, age, diabetes mellitus, arterial hypertension, dyslipidemia, smoking habits, family history of CAD, history of previous myocardial infarction, serum glucose, circulating lipid levels, duration of CAD, antihypertensive medication, antidiabetic drugs, statin therapy and treatment with β-blockers.ConclusionsElevated Lp-PLA2 levels relate to endothelial dysfunction and arterial stiffness in patients with stable CAD independently from classical risk factors for CAD, statin use, antihypertensive treatment, and duration of the disease.

Experimental measurement and modeling analysis of active and passive mechanical properties of arterial vessel wall

Coronary artery diseases (CAD) have always been serious threats to human health. The measurement, constitutive modeling, and analysis of mechanical properties of the blood vessel wall can provide a tool for disease diagnosis, stent implantation, and artificial artery design. The vessel wall has both active and passive mechanical properties. The passive mechanical properties are mainly determined by elastic and collagen fibers, and the active mechanical properties are determined by the contraction of vascular smooth muscle cells (VSMC). Substantial studies have shown that, the two-layer model of the vessel wall can feature the mechanical properties well, and the circumferential, axial and radial strain and stress are of great significance in arterial wall mechanics. This study reviewed recent investigations of mechanical properties of the vessel wall. Challenges and opportunities in this area are discussed relevant to the clinical treatment of coronary artery diseases.

Association of Soluble Suppression of Tumorigenesis-2 (ST2) with Endothelial Function in Patients with Ischemic Heart Failure.

Soluble suppression of tumorigenesis-2 (sST2) has been introduced as a marker associated with heart failure (HF) pathophysiology and status. Endothelial dysfunction is a component underlying HF pathophysiology. Therefore, we examined the association of arterial wall properties with sST2 levels in patients with HF of ischemic etiology. We enrolled 143 patients with stable HF of ischemic etiology and reduced left ventricular ejection fraction (LVEF) and 77 control subjects. Flow-mediated dilation (FMD) was used to evaluate endothelial function and pulse wave velocity (PWV) to assess arterial stiffness. Although there was no significant difference in baseline demographic characteristics, levels of sST2 were increased in HF compared to the control (15.8 (11.0, 21.8) ng/mL vs. 12.5 (10.4, 16.3) ng/mL; p < 0.001). In the HF group, there was a positive correlation of sST2 levels with age (rho = 0.22; p = 0.007) while there was no association of LVEF with sST2 (rho = −0.119; p = 0.17) nor with PWV (rho = 0.1; p = 0.23). Interestingly, sST2 was increased in NYHA III [20.0 (12.3, 25.7) ng/mL] compared to patients with NYHA II (15.0 (10.4, 18.2) ng/mL; p = 0.003) and inversely associated with FMD (rho = −0.44; p < 0.001) even after adjustment for possible confounders. In patients with chronic HF of ischemic etiology, sST2 levels are increased and are associated with functional capacity. There is an inverse association between FMD and sST2 levels, highlighting the interplay between the dysfunctional endothelium and HF pathophysiologic mechanisms.

Polarization-sensitive OFDI findings of vascular tissue response following drug-eluting stent implantation in patients with coronary artery disease

Abstract Intravascular polarimetry (IVP) with polarization-sensitive (PS-) optical frequency domain imaging (OFDI) measures polarization properties of the coronary arterial wall in parallel with the conventional OFDI images (Figure 1A). Tissues rich in collagen and smooth muscle cells (SMCs) appear birefringent, while the presence of lipid and macrophages causes depolarization. Because drug-eluting stents (DES) are designed to prevent SMC proliferation and collagen deposition, we hypothesized that neointimal tissue would exhibit low birefringence. The accumulation of lipid-laden macrophages characteristic of neoatherosclerosis should result in notable depolarization. Methods This study included 19 DES imaged with PS-OFDI in 13 patients (median follow-up period of 1.5 years). Coronary segments stented &amp;gt;90 days were analyzed every 1 mm. We analyzed polarization properties of the neointima in a total of 455 frames, and in additional 97 frames of native atherosclerosis remote from the stented segments. Neointima, delineated by the lumen and the inner boundary of the stent, was manually segmented in the intensity images using MATLAB. The median birefringence in all areas of the segmented neointima featuring a depolarization of ≤0.2 and the median depolarization across the entire neointima were computed for each frame after masking the guidewire shadow. Frames presenting intensity features of macrophages, lipid or calcifications extending to at least one adjacent frame were classified as neoatherosclerosis (n=112), and otherwise as normal neointima (n=343). For comparison with neoatherosclerosis, polarization properties of native atherosclerosis (n=97) were measured. We also categorized all frames of a stented segment according to the presence of in-stent restenosis (ISR) and/or stent thrombosis (ST) (204 frames from 5 patients). A generalized linear model using a generalized estimating equation or one-way ANOVA was used for statistical analysis. Results The major findings of the present study are: 1) neoatherosclerosis exhibited lower birefringence than native atherosclerosis (p&amp;lt;0.001, Figure-1B); 2) depolarization was positively associated with neoatherosclerosis (β=0.86, p&amp;lt;0.001) and ISR/ST (β=0.72, p=0.002), while birefringence was not (Figure 1C); 3) birefringence was positively correlated with the duration after DES implantation (β=5.22×10–3, p&amp;lt;0.001, Figure 1D). For the detection of neointimas within stents with ISR, the best cut-off value for depolarization was 0.033 with a sensitivity of 77% and a specificity of 57% (AUC=0.72). For comparison, using only conventional OFDI parameters to detect stents with ISR, the AUC were 0.52 for calcium area, 0.62 for lipid arc, and 0.63 for macrophage accumulations. Conclusions This study suggests that IVP provides quantitative assessment of vascular healing after DES implantation and may help clinical decision making in patients at high risk of stent failure. Figure 1 Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): This work was supported by the National Institutes of Health.

Consideration of stiffness of wall layers is decisive for patient-specific analysis of carotid artery with atheroma.

The paper deals with the impact of chosen geometric and material factors on maximal stresses in carotid atherosclerotic plaque calculated using patient-specific finite element models. These stresses are believed to be decisive for the plaque vulnerability but all applied models suffer from inaccuracy of input data, especially when obtained in vivo only. One hundred computational models based on ex vivo MRI are used to investigate the impact of wall thickness, MRI slice thickness, lipid core and fibrous tissue stiffness, and media anisotropy on the calculated peak plaque and peak cap stresses. The investigated factors are taken as continuous in the range based on published experimental results, only the impact of anisotropy is evaluated by comparison with a corresponding isotropic model. Design of Experiment concept is applied to assess the statistical significance of these investigated factors representing uncertainties in the input data of the model. The results show that consideration of realistic properties of arterial wall in the model is decisive for the stress evaluation; assignment of properties of fibrous tissue even to media and adventitia layers as done in some studies may induce up to eightfold overestimation of peak stress. The impact of MRI slice thickness may play a key role when local thin fibrous cap is present. Anisotropy of media layer is insignificant, and the stiffness of fibrous tissue and lipid core may become significant in some combinations.

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 adaptationWhat 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