Properties Of Vessel Wall Research Articles

Large artery vessel wall properties are impaired in patients with systemic scleroderma

Large artery vessel wall properties are impaired in patients with systemic scleroderma

Arterial vessel wall properties in primary hyperparathyroidism before and after para-thyroidectomy—a follow-up study

Arterial vessel wall properties in primary hyperparathyroidism before and after para-thyroidectomy—a follow-up study

Gefäßwandveränderungen bei Niereninsuffizienz

Cardiovascular events are the main cause of death in patients with end-stage renal disease. Functional and structural alterations of the arterial system substantially contribute to the high cardiovascular mortality in these patients. Structural alterations of the arterial wall comprise intima-media thickening and atherosclerotic plaque formation. Moreover, mechanical vessel wall properties of large arteries are significantly disturbed. This is already observed in young patients. Reduced arterial distensibility impairs large artery cushioning function. This results in increased ventricular afterload promoting left ventricular hypertrophy and in reduced coronary perfusion. After renal transplantation, structural alterations of the arterial wall and disturbed mechanical vessel wall properties persist. Moreover, renal failure is characterized by a severe impairment of endothelial function. Disturbed endothelial function results from reduced production of endothelium-dependent endogenous vasodilators and/or blunted vascular effects of these substances. Uremia is associated with the accumulation of an endogenous inhibitor of the endothelial nitric oxide synthase. Impaired endothelial function in renal failure promotes the progression of structural lesions of the arterial wall. Also in renal transplant recipients, substantially impaired endothelial function is observed despite correction of uremia. Hyperparathyroidism commonly observed in renal failure contributes to the disturbed functional vessel wall properties of large arteries. In patients with end-stage renal disease, decreased large artery distensibility is an independent risk factor for increased cardiovascular mortality. This may apply also to intima-media thickening and to impaired endothelial function.

Alterations of arterial vessel wall properties in hyperparathyroidism

Alterations of arterial vessel wall function are associated with increased cardiovascular morbidity and can be measured by noninvasive ultrasound techniques. There is increasing evidence that hyperparathyroidism contributes not only to structural changes of the cardiovascular system but to disturbances in functional arterial vessel wall properties. It has been shown that elevated concentrations of parathyroid hormone are associated with decreased arterial distensibility and increased intima-media thickness in patients with renal insufficiency. A permissive role of parathyroid hormone in the pathogenesis of uremic vessel wall changes has been discussed. The endothelium is a newly recognized target organ of parathyroid hormone. In patients with primary hyperparathyroidism endothelial dysfunction has been demonstrated, that seems to be reversible after parathyroidectomy. Effects on arterial vessel wall function may contribute to increased blood pressure observed in hyperparathyroidism. The complex cardiovascular effects of parathyroid hormone and changes in vascular tone, arterial distensibility and endothelial function in hyperparathyroidism are discussed.

Effect of age on brachial artery wall properties differs from the aorta and is gender dependent: a population study.

Compliance and distensibility are wall properties of large arteries, which may play a role in cardiovascular disease. The purpose of this study was to investigate whether the influence of age on these vessel wall properties differs between vascular territories and is gender-dependent. In a population sample of 498 men and women 20 to 79 years of age, diameter, distensibility, and compliance coefficient of the muscular brachial artery were measured with an echo-tracking device. Distensibility of the aorta was measured with the use of pulse-wave velocity. The effects of age and gender were assessed and adjusted for confounding factors such as mean blood pressure, pulse rate, body mass index, smoking, alcohol intake, and antihypertensive treatment. Covariance analysis showed no relation between gender and distensibility of the elastic aorta. Distensibility of the muscular brachial artery was lower in men, whereas men had a larger diameter and larger compliance of the brachial artery. With age, distensibility of the aorta decreased in both sexes to the same extent, whereas distensibility of the brachial artery did not change significantly. With age, brachial artery diameter increased; this increase was more pronounced in women. In men brachial artery compliance did not change with age, whereas in women compliance of the brachial artery increased with age. This study (1) confirms that distensibility of the aorta, an elastic artery, decreases with age. (2) In contrast to the aorta, after adjustment for confounding factors, in both men and women, no relation exists between age and distensibility of the muscular brachial artery. (3) Brachial artery diameter increase with age is more pronounced in women than in men. (4) In contrast to the well-known decrease in arterial compliance of elastic arteries with age, brachial artery compliance is not decreased with age and is increased in women. In conclusion, the effect of age on large-artery wall properties is not uniform but depends on gender and vascular territory.

Пептидоглікан змінює механічні властивості стінок судин еластичного типу

Пептидоглікан змінює механічні властивості стінок судин еластичного типу

Noninvasive assessment of the viscoelasticity of peripheral arteries

Currently used methods of examining the mechanical properties of blood vessel walls are either indirect or invasive, or measure vessel diameter and pressure waveforms at different sites. We developed a noninvasive technique to assess the mechanical properties and viscoelasticity of peripheral arteries. The pressure-strain elastic modulus (Ep) and the viscoelastic properties (energy dissipation ratio, EDR) of the common carotid artery (CCA), brachial artery (BA), radial artery (RA) and dorsalis pedis artery (DPA) were determined by means of palpating pressure and diameter distension waveforms extracted from high-resolution ultrasonography. The methodology was validated in vitro using an elastic tube phantom, as well as in vivo. In vivo study in 10 healthy volunteers (mean age 22 y) showed that the pressure-diameter curves were nonlinear, with an inflection at about 85–90 mmHg, and routed clockwise with slight hysteresis. The CCA ( n = 5) had a mean diameter of 6.74 mm and the pulsatile diameter distension was 12.2%. The Ep calculated at the CCA was 0.44 × 10 6 dyne/cm 2 with an EDR of 7.18%. The BA, RA and DPA ( n = 10) had mean diameters of 3.91 mm, 2.21 mm and 2.12 mm; arterial strains of 4.60%, 4.25% and 8.91%; mean Ep of 1.39, 1.45, 0.90 × 10 6 dyne/cm 2; and mean EDRs of 6.34%, 6.15% and 5.60%, respectively. The method presented is relatively simple to implement clinically and has potential as a new diagnostic tool for detecting local vascular changes.

Flow-mediated vasodilation and distensibility in relation to intima-media thickness of large arteries in mild essential hypertension

Whether endothelial dysfunction in essential hypertension is a cause or a consequence of structural vessel wall alterations is not known. The purpose of the present study was to compare flow-mediated vasodilation and mechanical vessel wall properties of large arteries between never treated mild essential hypertensive patients with normal intima-media thickness (IMT) and those exhibiting intima-media thickening. We measured brachial and carotid artery diameter and distension by Doppler frequency analysis of vessel wall movements in M-mode in ten essential hypertensive patients with normal carotid artery IMT (HYP1), in ten patients with increased IMT (HYP2), and in 13 normotensive control subjects (CON). Thereafter, we measured changes in brachial artery (BA) diameters during distal reactive hyperemia after 4 min of forearm occlusion. Nitroglycerin-mediated vasodilation was measured to assess endothelium-independent vasodilation, and BA blood flow was estimated using a pulsed Doppler system. Intima-media thickness of the carotid arteries was examined by high resolution B-mode ultrasound. IMT was 0.66 ± 0.02 mm in the HYP1 group, 0.84 ± 0.03 mm in the HYP2 group ( P < .01 v HYP1, P < .01 v CON), and 0.71 ± 0.04 mm in the CON group. Forearm occlusion was reduced in both the HYP1 group (3.4% ± 3.6%, P < .01 v CON) and the HYP2 group (6.4% ± 1.5%, P < .05 v CON) when compared with the CON group (16.5% ± 2.8%). Nitroglycerin-mediated vasodilation and BA blood flow were not different between study groups. BA distension (as well as carotid artery distension) was significantly lower in the HYP1 group (52 ± 6 μm, P < .05 v CON), but not in the HYP2 group (72 ± 10 μm) when compared with the CON group (88 ± 13 μm). The data suggest that endothelial dysfunction and reduced distensibility of large arteries in patients with essential hypertension occur in the absence of structural vessel wall alterations.

Common carotid intima-media thickness and arterial stiffness: indicators of cardiovascular risk in high-risk patients. The SMART Study (Second Manifestations of ARTerial disease).

Common carotid intima-media thickness (IMT) and distensibility are markers of structural and functional vessel wall properties. Both parameters have been found in population-based studies to be associated with cardiovascular risk factors and prevalent cardiovascular disease. We investigated cross-sectionally whether IMT and distensibility are associated with cardiovascular risk in patients who already have vascular disease or atherosclerotic risk factors and evaluated the diagnostic ability of IMT and distensibility to discriminate between low- and high-risk patients. IMT and distensibility (change of diameter) of the left and right common carotid arteries were measured in the first 570 patients (537 for distensibility) enrolled in the Second Manifestations of ARTerial disease (SMART) study, a cohort study among patients with a manifestation of vascular disease or cardiovascular risk factors. Three risk scores were used to classify each patient's vascular risk. Areas under the curve (AUCs) of receiver-operating characteristic curves were calculated for IMT and distensibility after the patients were dichotomized on the median of the risk scores as the outcome. Risk scores increased nearly linearly with increasing IMT and decreasing distensibility. The AUCs for IMT predicting high-risk patients were 0.77, 0.73, and 0.77 based on the 3 risk scores. The AUCs for distensibility were 0. 65, 0.62, and 0.66. Common carotid IMT and distensibility are clear markers of cardiovascular risk in patients who already have vascular disease or atherosclerotic risk factors. IMT appears to discriminate between low- and high-risk patients better than distensibility.

An integrated system for the non-invasive assessment of vessel wall and hemodynamic properties of large arteries by means of ultrasound

Objectives: To integrate methods for non-invasive assessment of vessel wall properties (diastolic diameter, distension waveform and intima-media thickness) and hemodynamic properties (blood flow velocity and shear rate distribution) of large arteries by means of dedicated ultrasound signal processing. Methods: we have developed an arterial laboratory (ART-lab) system. ART-lab consists of software running on a standard personal computer, equipped with a data acquisition card for the acquisition of radio frequency (RF) ultrasound signals obtained with a conventional echo scanner. It operates either (1) off-line or (2) in real-time. Real-time operation is restricted to the assessment of vessel wall properties because of limitations in computational power. Results: This paper provides an overview of ART-lab ultrasound radio frequency data acquisition and dedicated RF-signal processing methods. The capabilities of the system are illustrated with some typical applications. Conclusions: ART-lab in real-time mode is a useful tool for monitoring arterial vessel wall dynamics, while off-line it can be employed to investigate the elastic vessel wall properties in combination with hemodynamics, such as blood flow velocity and shear rate distribution.

Vessel wall properties in physiological nitric oxide production

Vessel wall properties in physiological nitric oxide production

Studies on cardiac sympathovagal balance and large artery distensibility in patients with untreated essential hypertension.

Power spectral analysis of heart rate variability and arterial distensibility are non-invasive measures of cardiac autonomic modulation and mechanical vessel wall properties, respectively. The aim of the present study was to assess cardiac sympathovagal balance, carotid and brachial artery distensibility and a possible relation between these parameters in mildly hypertensive patients as compared to normotensive controls. Total power (TP, 0.01 to 0.5 Hz) and spectral components (low frequency 0.04-0.15 Hz, mainly sympathetic cardiac modulation; high frequency 0.15-0.4 Hz, mainly vagal cardiac modulation) and cardiac sympathovagal balance (LF/LH ratio) of short term heart rate variability (ECG-recording) were calculated in 15 untreated essential hypertensive patients (HYP) and 15 age- and sex-matched healthy controls (CON). Brachial and carotid artery distensibility coefficient (DC) was measured with a multigate doppler system (echo-tracking). TP (ms2 x 10(-3)) (11.2 +/- 0.8 vs 13.6 +/- 0.9, P < 0.03), LF/HF ratio (1.07 +/- 0.08 vs 0.75 +/- 0.07, P < 0.01) and HF (ms2 x 10(-3)/%) (0.7 +/- 0.1/49 +/- 2 vs 1.3 +/- 0.2/58 +/- 2, P < 0.01/P < 0.01) were significantly reduced in HYP compared to CON subjects. LF (ms2 x 10(-3)/%) was 0.7 +/- 0.1/50 +/- 2 vs 0.9 +/- 0.1/41 +/- 2, P = 0.16/P < 0.01. Carotid artery DC (15 +/- 2 vs 26 +/- 2, P < 0.001) and brachial artery DC (4.7 +/- 0.6 vs 9 +/- 1.0, P < 0.001) were significantly reduced in HYP. There was a significant correlation between carotid DC and LF/HF (rho = -0.41, P < 0.03). The data shows reduced heart rate variability and altered cardiac sympathovagal balance as well as impaired arterial distensibility in untreated mildly hypertensive patients. The relative increase in sympathetic modulation and decreased carotid distensibility appear to be related.

A noninvasive method to estimate pulse wave velocity in arteries locally by means of ultrasound

Noninvasive evaluation of vessel wall properties in humans is hampered by the absence of methods to assess directly local distensibility, compliance, and Young’s modulus. Contemporary ultrasound methods are capable of assessing end-diastolic artery diameter, the local change in artery diameter as a function of time, and local wall thickness. However, to assess vessel wall properties of the carotid artery, for example, the pulse pressure in the brachial artery still must be used as a substitute for local pulse pressure. The assessment of local pulse wave velocity as described in the present article provides a direct estimate of local vessel wall properties (distensibility, compliance, and Young’s modulus) and, in combination with the relative change in artery cross-sectional area, an estimate of the local pulse pressure. The local pulse wave velocity is obtained by processing radio frequency ultrasound signals acquired simultaneously along two M-lines spaced at a known distance along the artery. A full derivation and mathematical description of the method to assess local pulse wave velocity, using the temporal and longitudinal gradients of the change in diameter, are presented. A performance evaluation of the method was carried out by means of experiments in an elastic tube under pulsatile pressure conditions. It is concluded that, in a phantom set-up, the assessed local pulse wave velocity provides reliable estimates for local distensibility.

A longitudinal study of vessel wall properties in normotensive and hypertensive renal transplant recipients.

The mechanisms responsible for reduced arterial distensibility in renal transplant recipients remain to be evaluated. The present longitudinal study was aimed to evaluate the effect of hypertension on the evolution of vessel wall properties in renal transplant recipients. The mechanical properties of the common carotid artery were determined in 24 normotensive and 24 treated hypertensive renal transplant recipients 6-12 weeks after transplantation. The measurements were repeated after 2 years. Arterial distension was determined by using a multigate pulsed Doppler system, blood pressure (BP) was measured by a mercury sphygmomanometer. BP was 127 +/- 3/80 +/- 2 mm Hg at entry and 133 +/- 3/82 +/- 2 mm Hg after 2 years in the normotensive group, 146 +/- 4/90 +/- 3 mm Hg at entry and 145 +/- 3/87 +/- 2 mm Hg after 2 years in the hypertensive group (P < 0.01, normotensives vs hypertensives). The distensibility coefficient (DC) decreased significantly after 2 years in the hypertensive group (DC 18.3 +/- 1.3 10(-3)/kPa before, 15.1 +/- 1.2 10(-3)/kPa after 2 years, P < 0.05) whereas no significant change was observed in the normotensive group (DC 19.0 +/- 1.4 10(-3)/kPa before, DC 17.8 +/- 1.3 10(-3)/kPa after 2 years, NS). There was a significant correlation between the change of the distensibility coefficient after 2 years and mean arterial pressure (n = 48, r = 0.42, P < 0.01). The results show that the decrease of arterial distensibility after 2 years is accelerated in hypertensive renal transplant recipients despite effective anti-hypertensive treatment. Since BP levels were not different at entry into the study and after 2 years, differences in distending pressure along cannot explain the more pronounced decrease of arterial distensibility over time in hypertensive renal transplant recipients.

Effect of hyperparathyroidism on arterial distensibility in renal transplant recipients

The cushioning function of the arterial system is altered in patients with end-stage renal failure. The role of hyperparathyroidism for the altered vessel wall properties of large arteries not known. To exclude the confounding effects of fluid volume changes and hypercirculation as well as uremic toxicity on vessel wall properties from those of hyperparathyroidism, the present study was conducted in 54 normotensive renal transplant recipients with good graft function, three to six months after transplantation. The vessel wall properties of the common carotid artery were investigated in 32 of them, who had increased plasma intact parathyroid hormone (iPTH) levels (136 +/- 12 ng/liter, SEM), and compared to those of 22 control recipients of same age with normal plasma iPTH levels (34 +/- 4 ng/liter). Arterial distension was measured by Doppler analysis of the vessel wall movements, blood pressure was determined by sphygmomanometry. Blood pressure was 140 +/- 3/85 +/- 2 mm Hg in renal transplant recipients with hyperparathyroidism, 135 +/- 3/83 +/- 1 mm Hg in patients with normal plasma iPTH levels (NS). There was no difference in enddiastolic diameter of the common carotid artery (7.4 +/- 0.2 mm) in renal transplant recipients with hyperparathyroidism as compared with the control patients (7.3 +/- 0.2 mm; NS). Renal transplant recipients with hyperparathyroidism had a lower distension (389 +/- 27 microns vs. 486 +/- 28 microns, P < 0.05) and distensibility coefficient of the common carotid artery (15.1 +/- 1.1 10(-3)/kPa vs. DC 19.0 +/- 1.0 10(-3)/kPa, P < 0.001) when compared with the control patients. Multiple regression analysis showed that the distensibility coefficient of the common carotid artery was negatively correlated with age (P < 0.001), mean arterial blood pressure (P < 0.05) and plasma iPTH levels (P < 0.05). The effects of plasma iPTH levels were not related to serum calcium concentrations or to differences in the enddiastolic diameter of the common carotid artery. The data suggest that secondary hyperparathyroidism can affect the cushioning function of larger arteries in patients with end-stage renal failure independently of high blood pressure.

Dynamic vessel wall properties and their reproducibility in subjects with increased cardiovascular risk.

To determine reproducibility figures of dynamic arterial wall properties such as cross-sectional compliance (CC) and distensibility (DC) in subjects with increased cardiovascular risk, in comparison with healthy adults. A total of 34 persons were divided into three groups with varying cardiovascular risk factors. Diameters (D) and diameter changes (deltaD) during the heart cycle of both common carotid (CCA) and right common femoral (CFA) arteries were measured by a vessel wall movement detector system. Blood pressures (BP) were recorded non-invasively by a semi-automated oscillometric device. CC (=piD(deltaD/2deltaP) in unit mm2/kPa) and DC (=2deltaD/D)/deltaP in unit 10(-3)/kPa) were calculated from the above-mentioned parameters. Measurements were performed twice during one visit and twice again with a time interval of at least 3 days to determine intra-observer intra- and intersession variability. Reproducibility figures of CC and DC of the CCA varied between 8 and 12%, and between 13 and 22% for the CFA. Intra-observer intra- and intersession variability were similar in the three groups. In our studies the reproducibility of dynamic vascular wall properties determined by ultrasound was good. Despite differences in the absolute values for CC and DC in groups with increased cardiovascular risk, mean reproducibility figures remained at a similar level (8-12%) as in healthy volunteers.

Sodium, blood pressure, and arterial distensibility in insulin-dependent diabetes mellitus.

We investigated 24-hour ambulatory blood pressure and arterial distensibility, a marker of biophysical vessel wall properties, in 32 normoalbuminuric type I diabetic patients and 32 healthy control subjects on diets containing 50 mmol and 200 mmol sodium per day. The increase in daytime diastolic blood pressure from 50 to 200 mmol sodium was significantly higher in the diabetic patients than in the control subjects (2.3+/-4.9 versus 0.2+/-3.7 mm Hg, P<.05). On a high sodium regimen, femoral artery distensibility was decreased in the diabetic patients compared with the control subjects (19.2+/-7.6 versus 24.1+/-9.3 10[-3]/kPa, P<.05). Angiotensin-converting enzyme inhibition in the diabetic patients on a high sodium diet decreased daytime diastolic blood pressure and increased femoral artery distensibility. The blood pressure decrease in response to angiotensin-converting enzyme inhibition correlated significantly with the blood pressure increase to sodium (for 24-hour systolic and diastolic blood pressure, r=.72, P<.001 and r=.76, P<.001). In addition, we found that in the diabetic patients on a high sodium diet, the renal blood flow response to exogenous angiotensin II was not bimodally distributed, as is the case in essential hypertension, in which a subgroup of the patients are characterized by sodium sensitivity of the blood pressure and an abnormal renal blood flow response to exogenous angiotensin II ("nonmodulator phenotype"). These results show that blood pressure in insulindependent diabetes mellitus is sodium sensitive, but that this is not related to the nonmodulator phenotype, and suggest that in IDDM a relatively high sodium intake may be a factor that predisposes to the development of diabetic vascular disease.

The acute effect of hyperglycaemia on vessel wall properties

Arterial distensibility is a marker of functional and structural vessel wall properties. A decreased distensibility is an important risk factor for cardiovascular disease. In insulin-dependent diabetes mellitus of short duration, arterial stiffness has been reported to be increased, decreased or the same as in healthy control subjects. The influence of acute hyperglycaemia on arterial stiffness is unclear and might be one of the factors responsible for the divergent results which have been observed. We investigated arterial distensibility locally in the carotid artery during hyper- and normoglycaemia using a glucose clamp technique. Eleven healthy normotensive men underwent both a hyperglycaemic and a euglycaemic clamp on separate days. Before and after 2 h of clamping, arterial diameter (D) and change in arterial diameter during the heart cycle (dD) were measured with a non-invasive vessel wall movement detector system. Blood pressure (BP), pulse pressure (dP) and heart rate (HR) were recorded with a semi-automated device. Distensibility coefficients (DC), reflecting the intrinsic vascular wall elasticity, and compliance coefficients (CC), reflecting the buffering capacity of the vessel, were calculated from D, dD and dP. (DC=2*dD/D*dP, CC=π*dD*D/2*dP). There were no significant differences between the hyperglycaemic and the euglycaemic clamp for D, DC and CC. These results suggest that an acute systemic hyperglycaemia is not responsible for changes in diameter, distensibility and compliance of the carotid artery.

Common carotid artery wall properties in Takayasu's arteritis.

The vessel wall properties of the common carotid artery have been noninvasively and quantitatively assessed with an ultrasonic instrument. Stiffness parameter beta, which represents the mechanical properties of the vessel, was calculated from the relationship between blood pressure and the diameter of the artery. There are no reports that quantitatively assess wall properties in Takayasu's arteritis. The authors compared, in vivo, the vessel wall properties of the common carotid artery in 14 patients with Takayasu's arteritis versus those in 60 normal subjects (controls). They measured changes in the inner diameter of the artery between systole and diastole with an ultrasonic, phase-locked, echo-tracking system. Beta was significantly higher in Takayasu's arteritis than in normal subjects (better than a 99% confidence interval). The findings for each decade were as follows: 3rd decade (20s): 35.7 +/- 28.9 vs 5.01-6.46, P=0.0001; 4th decade (30s): 19.5 +/- 9.71 vs 6.09-7.80, P=0.02; 5th decade (40s): 26.2 +/- 11.3 vs 7.26-9.28, P = 0.0001; 6th decade (50s): 19.1 +/- 4.27 vs 8.66-11.25, P = 0.0001. Takayasu's arteritis significantly impaired the mechanical performance of the common carotid artery. Thus, beta shows promise as a useful diagnostic indicator of Takayasu's arteritis.

Influence of insulin resistance on vessel wall properties of large arteries: J.J. Spek; J.A. Staessen 1; A.P.G. Hoeks 2, H.A.J. Struijker Boudier, L.M.A.B. van Bortel. Departments of Pharmacology and 2 Biophysics, Cardiovascular Research Institute, University of Limburg, Maastricht, Netherlands; 1 Hypertension Unit, University of Leuven, Leuven, Belgium

Influence of insulin resistance on vessel wall properties of large arteries: J.J. Spek; J.A. Staessen 1; A.P.G. Hoeks 2, H.A.J. Struijker Boudier, L.M.A.B. van Bortel. Departments of Pharmacology and 2 Biophysics, Cardiovascular Research Institute, University of Limburg, Maastricht, Netherlands; 1 Hypertension Unit, University of Leuven, Leuven, Belgium