Elastic Properties Of Arterial Wall Research Articles

Effects of acute cervical stretching on arterial wall elastic properties.

Purpose: Acute (immediate) or regular (mid- or long-term) stretching increases arterial compliance and reduces arterial stiffness. Stretching is widely known to induce arterial functional factor changes, but it is unclear whether stretching alters arterial structural factors. Ultrasound shear wave elastography can quantify the distribution of tissue elastic properties as an index of arterial structural factors. This study thus aimed to examine the effects of acute cervical stretching on arterial wall tissue elastic properties. Methods: Seventeen healthy young adults participated in two different trials for 15min in random order on separate days: a resting and sitting trial (CON) and a supervised cervical stretching trial (CS). In CS, subjects performed 10 different stretches. At each site, the stretch was held for 30s followed by a 10-s relaxation period. In CON, subjects rested on a chair for 15min. Results: After the experiment, carotid arterial compliance, assessed by combined ultrasound imaging and applanation tonometry, was significantly increased in CS, but not in CON. However, there was no significant change in tissue elasticity properties of the arterial wall in either trial, as assessed by ultrasound shear wave elastography. Conclusion: Acute cervical stretching significantly increased carotid artery compliance in young participants, but did not reduce elastic tissue properties (i.e., arterial structural factors) of the carotid artery wall. These results strongly suggest that changes in structural factors have little relation to stretching-induced acute increases in arterial compliance.

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<.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.

Effects of novel antidiabetic agents on the arterial wall elastic properties as a marker of vascular function in patients with type 2 diabetes mellitus

Effects of novel antidiabetic agents on the arterial wall elastic properties as a marker of vascular function in patients with type 2 diabetes mellitus

461-P: Prothrombotic State Is Associated with Impaired Arterial Wall Elastic Properties in Patients with Type 2 Diabetes Mellitus

Background: Arterial stiffness is a prominent macrovascular complication in patients with type 2 diabetes mellitus (DM2). Antiplatelet therapy is the cornerstone of CVD therapy. There is little evidence about the influence of antiglycemic agents on arterial wall properties and prothrombotic state. Methods: We enrolled 80 consecutive patients (males=64.4%), aged 64.19 ± 8.82 years receiving either metformin plus another antiglycemic agent such as sulphonylureas, DPP-4i, GLP-1 agonists, insulin, or metformin alone (n=16 per group). Applanation tonometry was used to assess aortic pulse wave velocity (PWV) as a measure of arterial stiffness. Platelet reactivity was measured with PFA-200, collagen/epinephrine (CEPI) and PFA-200 collagen/ADP closure time (CADP). Results: There was no difference between the study groups regarding gender, age, hypertension, dyslipidemia, smoking, PWV, CADP or CEPI (p=NS for all). When conducting a separate analysis between patients receiving aspirin (AS), dual antiplatelet therapy (DAPT) and those without antiplatelet therapy (nAPT), we observed that nAPT patients exerted significantly lower CEPI values (134.42 ± 40 s for nAPT vs. 170.36 ± 64 s for AS vs. 178.90 ± 74 s for DAPT, p=0.03). PWV was 10.96 ± 2.54 m/s for nAPT vs. 11.20 ± 2.88 m/s for AS vs. 10.82 ± 2.76 m/s for DAPT (p=0.9). Within-group analysis showed that CEPI values were significantly reduced in nAPT under sulphonylureas (121 s vs. 243 s vs. 262 s for nAPT, AS and DAPT respectively, p=0.02) or GLP-1 (138 s vs. 203 s vs. 168 s for nAPT, AS and DAPT respectively, p=0.05). Additionally, we found an inverse, linear association between CEPI and PWV (rho= -0.45, p=0.02) and CADP and PWV (rho= -0.04, p=0.05) in nAPT patients alone. Conclusion: Increased prothrombotic state is associated with impaired arterial wall elastic properties. Antidiabetic and antiplatelet treatment interactions may regulate the relationship between arterial stiffness and thrombosis in patients with DM2. Disclosure G. Siasos: None. P.K. Stampouloglou: None. K. Batzias: None. S.A. Paschou: None. A. Antonopoulos: None. V. Tsigkou: None. N. Gouliopoulos: None. M. Zaromytidou: None. S. Mazaris: None. E. Oikonomou: None. S. Tsalamandris: None. G. Vogiatzi: None. A. Thanopoulou: None. A. Vryonidou: None. M. Politou: None. D. Tousoulis: None. N. Tentolouris: None.

Breakfast association with arterial stiffness and carotid atherosclerotic burden. Insights from the ‘Corinthia’ study

Background and aimsThe role of dietary patterns, in cardiovascular diseases has been challenged. The role of breakfast as an element of balance energy intake has gained research interest. However, the effects of dietary patterns related to breakfast consumption on vascular function are unknown. We explored the association of breakfast consumption habits with arterial wall elastic properties and carotid atherosclerosis. Methods and resultsIn this cross-sectional study we enrolled 2043 inhabitants of the Corinthia region in Greece. Carotid-femoral pulse wave velocity (cf-PWV) was used to assess arterial stiffness. Carotid intima-media thickness (cIMT) was measured and the mean and the maximum cIMT were calculated. According to food frequency questionnaires, breakfast contribution in total daily energy intake (>20%; 5–20% and <5%) was estimated. Subjects were categorized as high-energy breakfast consumers (HeBC), low-energy breakfast consumers (LeBC) and those skipping breakfast (SBf) respectively. From the study population 240 subjects were categorized as HeBC, 897 as LeBC, and 681 as SBf. The mean cf-PWV was significantly higher in subjects SBf compared to LeBC and HeBC (9.35 ± 2.82 m/s vs. 9.09 ± 2.77 m/s vs. 8.76 ± 2.69 m/s, p = 0.02). The mean cIMT was significantly higher in subjects SBf compared to LeBC and HeBC (1.04 ± 0.46 mm vs. 0.99 ± 0.43 mm vs. 0.92 ± 0.39 mm, p = 0.01). Even after adjustment for potential confounders and cardiovascular risk factors SBf subjects have significantly increased mean cIMT and cf-PWV. ConclusionSkipping breakfast has an adverse effect on arterial stiffness and carotid atheromatic burden. Increased breakfast total energy intake may act protectively against atherosclerosis, a finding worth of further pathophysiologic exploration with potential clinical implications.

Power spectral estimation of high-harmonics in echoes of wall resonances to improve resolution in non-invasive measurements of wall mechanical properties in rubber tube and ex-vivo artery

The aim of this work is to develop a new type of ultrasonic analysis of the mechanical properties of an arterial wall with improved resolution, and to confirm its feasibility under laboratory conditions. Motivation: it is expected that this would facilitate a non-invasive path for accurate predictive diagnosis that enables an early detection & therapy of vascular pathologies. In particular, the objective is to detect and quantify the small elasticity changes (in Young’s modulus E) of arterial walls, which precede pathology. A submicron axial resolution is required for this analysis, as the periodic widening of the wall (under oscillatory arterial pressure) varies between ±10 and 20 μm. This high resolution represents less than 1% of the parietal thickness (e.g., << 7 μm in carotid arteries). The novelty of our proposal is the new technique used to estimate the modulus E of the arterial walls, which achieves the requisite resolution. It calculates the power spectral evolution associated with the temporal dynamics in higher harmonics of the wall internal resonance f0. This was attained via the implementation of an autoregressive parametric algorithm that accurately detects parietal echo-dynamics during a heartbeat. Thus, it was possible to measure the punctual elasticity of the wall, with a higher resolution (> an order of magnitude) compared to conventional approaches. The resolution of a typical ultrasonic image is limited to several hundred microns, and thus, such small changes are undetected. The proposed procedure provides a non-invasive and direct measure of elasticity by doing an estimation of changes in the Nf0 harmonics and wall thickness with a resolution of 0.1%, for first time. The results obtained by using the classic temporal cross-correlation method (TCC) were compared to those obtained with the new procedure. The latter allowed the evaluation of alterations in the elastic properties of arterial walls that are 30 times smaller than those being detectable with TCC; in fact, the depth resolution of the TCC approach is limited to ≈20 μm for typical SNRs. These values were calculated based on echoes obtained using a reference pattern (rubber tube). The application of the proposed procedure was also confirmed via “ex-vivo” measurements in pig carotid segments.

1949Pseudoexfoliative glaucoma: associations of systemic inflammation with endothelial dysfunction and impaired arterial wall elastic properties

1949Pseudoexfoliative glaucoma: associations of systemic inflammation with endothelial dysfunction and impaired arterial wall elastic properties

An Inverse Method to Determine Arterial Stiffness with Guided Axial Waves

Many cardiovascular diseases can alter arterial stiffness; therefore, measurement of arterial wall stiffness can provide valuable information for both diagnosis of such diseases in the clinic and evaluation of the effectiveness of relevant drugs. However, quantitative assessment of the in vivo elastic properties of arterial walls in a non-invasive manner remains a great challenge. In this study, we found that the elastic modulus of the arterial wall can be extracted from the dispersion curve of the guided axial wave (GAW) measured using the ultrasound elastography method. It is shown that the GAW in the arterial wall can be well described with the Lamb wave (LW) model when the frequency exceeds a critical value fc, whose explicit form is determined here based on dimensional analysis method and systematic finite-element simulations. Further, an inverse procedure is proposed to determine both fc and the elastic modulus of the arterial wall. Phantom experiments have been performed to validate the inverse method and illustrate its potential use in the clinic.

Mesoglycan improves vascular reactivity and insulin sensitivity in patients with metabolic syndrome

ObjectivesThe aim of this study was to evaluate the acute and chronic effects of mesoglycan on the endothelial function and arterial elastic properties in patients with metabolic syndrome (MetS). BackgroundMetS is defined by a clustering of vascular risk factors that demand both pharmacologic and non-pharmacologic interventions, including body weight reductions and physical activity. The correction of endothelial dysfunction and arterial wall distensibility associated with MetS have lately received increasing interest. MethodsThirty consecutive ambulatory patients affected by MetS were 2:1 randomized in a double-blind fashion to receive mesoglycan or placebo, respectively. In the first phase of the study, we evaluated the acute effects of a single i.m. administration of mesoglycan (60 mg) or placebo on vascular reactivity, as assessed by brachial flow-mediated dilation (FMD). Then, patients were chronically treated with mesoglycan per os (50 mg twice a day) or placebo for 90 days. At the end of this period, vascular reactivity and the arterial wall elastic properties were evaluated. ResultsIn the mesoglycan group, FMD increased above baseline after acute administration, with a maximum increment of 52% after 2 h. FMD was also significantly greater than baseline after 90 days of chronic treatment. In the placebo group, FMD was unaffected by both acute and chronic mesoglycan administration. Moreover, after 90 days of mesoglycan treatment, a marked improvement in arterial distensibility and compliance was detected and arterial stiffness reduced significantly. ConclusionsThis small, preliminary study shows that mesoglycan exerts relevant effects on vascular physiology, both in an acute setting as well as after prolonged, three-month treatment, in patients affected by metabolic syndrome.

AB0223 Atherosclerotic plaques may be correlating with the duration of rheumatoid arthritis

BackgroundBACKGROUND AND AIMS: It is widely accepted that patients with rheumatoid arthritis (RA) have increased mortality and morbidity from premature cardiovascular disease. Up to 50% of this excess mortality is...

Influence of pulse pressure variation on the results of local arterial compliance measurement: A computer simulation study

A computer simulation has been performed to study the influence of the pulse pressure variation on the arterial compliance readings in regard to different calculation techniques and arterial wall elastic properties. We applied the derivative- and amplitude-based (delta-based) calculation techniques to the model of the pressure vs. arterial lumen area relationship of different arteries. The simulated pulse pressure increase resulted in an essential reduction of the delta-based compliance in its near maximum region, and in an increase or no change outside this region. In the case of the relationship of a lower steepness the alterations were smaller.

Increased arterial stiffness in children on haemodialysis

Measures of aortic stiffness--aortic pulse wave velocity (PWV) and augmentation index (AIx)--have been shown to be powerful predictors of survival in adult haemodialysis (HD) patients. Very few data have been reported regarding arterial stiffness in paediatric renal populations. PWV and aortic AIx were determined from contour analysis of arterial waveforms recorded by applanation tonometry using a SphygmoCor device in 14 children on HD (age = 14.1 years) and in 15 age, height matched children controls. Pre-HD AIx (29.7 +/- 15.4%) and PWV (6.6 +/- 1.0 m/s) were significantly higher compared with children controls (8.3 +/- 8.0% and 5.4 +/- 0.6 m/s, respectively, P < 0.0001). The only significant difference between normal and HD children was BP level: 103/61 vs 114/72 mmHg, P < 0.05. In children of HD patients, a multiple linear regression model including BP, age, height, weight, Ca and P levels as independent variables accounted for 57% of the variability in AIx. Dialysis had no impact on AIx (post-HD: 28.5 +/- 12.7%) or on PWV (post-HD: 6.7 +/- 0.8 m/s). We show, in this first-ever report of increased arterial stiffness in children on dialysis, that end-stage renal disease is associated with abnormalities in arterial wall elastic properties, comparable with adult levels, even in childhood. Most importantly, the absence of a discernible amelioration with dialysis implies that purely structural and not functional alterations lie behind the increased arterial stiffness.

Large-artery elastic properties in young men : relationships to serum lipoproteins and oxidized low-density lipoproteins.

Measures of arterial elasticity have been proposed as surrogate markers for asymptomatic atherosclerosis. We investigated the relations of serum lipoproteins, oxidized low-density lipoprotein (ox-LDL), and familial hypercholesterolemia (FH) to arterial elasticity among young men. As a marker of arterial elasticity we measured compliance in the thoracic aorta by using magnetic resonance imaging and in the common carotid artery by using ultrasound. LDL diene conjugation was used as a marker of ox-LDL. In study I, 25 healthy men (aged 29 to 39) were classified into 2 extreme groups according to previously measured high-density lipoprotein cholesterol to total cholesterol ratio (HDL-C/TC ratio). In study II, the healthy men were used as controls for 10 age matched asymptomatic patients with FH. In healthy men, the group with low HDL-C/TC ratio had decreased carotid artery compliance (2. 3+/-0.4% versus 1.9+/-0.5%/10 mm Hg, P=0.034). In univariate analysis, the compliance of the carotid artery associated with ox-LDL (r =-0.49, P=0.016) and HDL-C/TC ratio (r=0.41, P=0.040). In multivariate regression analyses, ox-LDL was the only independent determinant for compliance of the carotid artery (P=0.016). Aortic elasticity was not related to standard lipid variables, but the compliance of the ascending aorta associated with ox-LDL (r=-0.44, P=0.030). In FH patients, arterial elasticity was similar to that in controls. We conclude that elasticity of the common carotid artery is affected by serum lipid profile in young men. The current study demonstrates for the first time an in vivo association between ox-LDL and arterial elasticity suggesting that oxidative modification of LDL may play a role in the alteration of arterial wall elastic properties.

Ultrasound evaluation of arterial wall elastic properties in patients with atherosclerotic lesions of vessels

Ultrasound evaluation of arterial wall elastic properties in patients with atherosclerotic lesions of vessels

Effects of short-term administration of sublingual nifedipine on coronary arterial wall elastic properties: evaluation by intravascular ultrasound.

Intravascular ultrasound is suited to measure coronary cross-sectional anatomy. Therefore the regional coronary wall elasticity was evaluated by examining the response to nifedipine. In 20 patients, coronary ostial pressure (P) and intravascular ultrasound images were simultaneously recorded before and after sublingual administration of 10 mg nifedipine. We identified the perimeter of the vessel wall, with normal or atherosclerotic plaque, on ultrasound image. At the atherosclerotic site, we measured segmental perimeter (S) for each normal or plaque segment. The ratio of the individual segment length (delta S/delta P) and cyclic variation of cross-sectional area (delta A/delta P) per mm Hg increase in P were calculated. Nifedipine decreased pressure (133/79-120/73 mm Hg) and increased heart rate (79-82 beats/min). After nifedipine, delta A/delta P increased from 8.5 +/- 10.2 x 10(-3) to 16.5 +/- 14.4 x 10(-3) mm2/mm Hg at 20 normal sites (p = 0.005) but was unchanged at 17 atherosclerotic sites (6.6 +/- 7.0 x 10(-3) to 6.7 +/- 7.1 x 10(-3) mm2/mm Hg). Nifedipine increased delta S/delta P in normal segments (4.5 +/- 8.7 x 10(-3) to 9.9 +/- 10.9 x 10(-3) mm/mm Hg; p = 0.02) but produced no change in segments with calcified or soft plaque (-1.1 +/- 0.3 x 10(-3) to 1.4 +/- 1.6 x 10(-3) mm/mm Hg and 5.0 +/- 3.6 x 10(-3) to 6.1 +/- 4.8 x 10(-3) mm/mm Hg, respectively). This study demonstrated that nifedipine increases regional coronary arterial elasticity at normal segments but not at that containing mildly atherosclerotic segment, and likely that the arterial wall function indicated by the response to nifedipine was impaired at an early stage of atherosclerosis.

Experimental Approaches on Measuring the Mechanical Properties and Constitutive Laws of Arterial Walls

Studies on the elastic properties of arterial walls which have been done for the past two decades are surveyed briefly. After several in vitro and in vivo experimental methods and clinical techniques for the measurements of the mechanical behavior of arterial walls have been reviewed, data obtained of the basic characteristics of the arterial wall, including wall incompressibility and anisotropy, are discussed. The author then reviews constitutive laws proposed for the description of stress-strain relationships of arterial walls and methods for the parametric expression of pressure-diameter data, and shows data on the effects of aging and vascular diseases on arterial mechanics. Finally, residual stress in the arterial wall is discussed.

Evaluation of arterial compliance-pressure curves. Effect of antihypertensive drugs.

A new high-precision ultrasonic device was developed to determine noninvasively arterial compliance as a function of blood pressure. Because of the nonlinear elastic properties of arterial walls, measurements of compliance can be appropriately compared only if obtained over a range of pressures. This apparatus was used to evaluate in a double-blind, parallel fashion the effect of three different antihypertensive drugs and of a placebo on radial artery compliance. Thirty-two normotensive volunteers were randomly allocated to an 8-day, once-a-day oral treatment with either a placebo, 100 mg atenolol, 20 mg nitrendipine, or 20 mg lisinopril. Blood pressure, heart rate, radial artery diameter, and arterial compliance were measured immediately before as well as 6 hours after dosing on the first and last days of the study. On the eighth day of administration, within 6 hours after dosing, lisinopril induced an acute increase in radial artery diameter, from 2.99 +/- 0.06 to 3.28 +/- 0.09 mm (mean +/- SEM, p less than 0.01). The compliance-pressure curve was shifted upward on day 1 (p less than 0.01) as well as on day 8 (p less than 0.05). None of the other drugs induced any significant modification of these parameters. Arterial compliance has a strong nonlinear dependency on intra-arterial pressure and therefore has to be defined as a function of pressure. Antihypertensive drugs acting by different mechanisms may have different effects on the mechanical properties of large arteries.

Effects of elastase on the stiffness and elastic properties of arterial walls in cholesterol-fed rabbits

The effect of cholesterol feeding and elastase administration on the arterial stiffness and elastic properties was investigated in rabbits by pressure-diameter tests on excised thoracic aortas, common carotid and femoral arteries. Rabbits in groups RA and RB were fed 1% cholesterol diet for 14 weeks. Groups RC and RD were fed the cholesterol diet for the first 7 weeks, and then given regular chow for the last 7 weeks. In addition, rabbits in groups RB and RC were administered elastase daily for the last 7 weeks. Rabbits in group RE were fed the regular chow for 14 weeks and served as the control group. The arterial stiffness and the elastic modulus of wall material in the RA rabbits were generally higher than those in the control rabbits. Administration of elastase and/or feeding of the regression diet decreased the wall stiffness and elastic modulus significantly, although the effect of elastase did not appear clearly when used in combination with the regression diet. The cholesterol feeding decreased the ratio of thickness to wall radius, whereas the ratio was more or less increased by the elastase administration and/or the regression diet.

Experimental cerebral vasospasm arterial wall mechanics and connective tissue composition.

The elastic properties of the basilar artery were studied in control and treated dogs in which 3 ml of blood was injected intracisternally. Vascular specimens were resected transclivally as cylindrical segments and their external diameters were measured in vitro in the pressure range from 0 mm Hg to 250 mm Hg in the active condition of smooth muscle in Krebs-Ringer solution and in the passive condition in saline solution. The development of cerebral vasospasm was confirmed comparing the diameter difference between these two conditions. The experimental data indicated that vasospasm was most prominent on the 7th day after the treatment of blood injection. In the passive condition no significant dimensional change (i.e. radius and wall thickness) was observed between the control and the treated arteries at various pressure levels. These results imply that the luminal narrowing under vasospasm is not attributable to an irreversible organic change in the wall but to the constriction of vascular smooth muscle. The treated arteries are more distensible and have lower elastic moduli than the control arteries, possibly due to a change in the content of their connective tissues. These changes of the passive elastic properties of arterial walls after blood injection might be one of the factors affecting the development of cerebral vasospasm.

Basic principles of electrohaemodynamics

Electrohaemodynamics (EHD) is a method of measuring cardiac output continuously, also cardiac index, stroke volume, blood flow through limbs, vascular resistance, useful work output from the heart, elastic properties of arterial walls, and contractile and rate of energy generation properties of heart muscle. The method is based on simultaneous measurements of the time variations of arterial blood pressure and electrical conductance in a portion of human body. The measurements, in the form of analogue signals, are processed by means of a microprocessor or a mini-computer. The processing is based on equations which combine haemodynamics with measurements of electrical conductance and arterial pressure variation. Direct comparison of simultaneous cardiac output measurements using EHD and thermal dilution, as well as indirect comparisons with the Fick and dye dilution methods, show that EHD is at least as accurate as these methods. The reproducibility of EHD is within one percent when the subjects are in the steady state, which appears to be better than any other known technique.