Carotid Compliance Research Articles

Dyssynchronous Systolic Expansion of Carotid Artery in Patients with Marfan Syndrome

Marfan syndrome is a multisystemic connective tissue disorder associated with a mutation affecting fibrillin-1, the main component of microfibrils. Fibrillin-1 gene mutations may affect the carotid arterial wall. The aim of this study was to investigate carotid arterial mechanics using Velocity Vector Imaging (VVI) in patients with Marfan syndrome. Forty-five patients (26 men; mean age, 39 ± 10 years) with Marfan syndrome who fulfilled the Ghent criteria and 45 gender-matched and age-matched healthy volunteers were evaluated. Transverse images of right common carotid artery proximal to the bifurcation were obtained for each subject and divided into six segments. The peak radial velocity, circumferential strain, and strain rate of the six segments were analyzed using VVI. The time to peak radial velocity (T(s)), peak circumferential strain (T(st)), and peak strain rate (T(sr)) of the six segments were calculated. Intima-media thickness was measured for each subject. The average diameter of the common carotid artery in patients with Marfan syndrome was significantly larger than that of controls. Carotid compliance coefficients and distensibility coefficients as assessed by B-mode echocardiographic images were comparable between the two groups. In VVI analyses, averages and standard deviations of peak radial velocities, circumferential strain, and strain rates were not significantly different between the two groups. However, T(s), T(st), and T(sr) were more delayed (P < .01), and the standard deviations of T(s), T(st), and T(sr) were significantly larger in patients with Marfan syndrome (P = .01, P < .01, and P < .01, respectively), suggesting delayed and dyssynchronous arterial expansion during systole. The presence of Marfan syndrome was independently and significantly related to increased standard deviations of T(st) (β = 0.33, P < .01) and T(sr) (β = 0.44, P < .01), even after adjusting for age in multiple regression analysis. In patients with Marfan syndrome, carotid arteries assessed with VVI exhibited delayed, dyssynchronous arterial expansion during systole compared with healthy controls. Arterial assessment using VVI may be useful for noninvasively quantifying vascular alterations associated with Marfan syndrome.

Greater Arterial Stiffness in Polycystic Ovary Syndrome (PCOS) Is an Obesity- But Not a PCOS-Associated Phenomenon

Polycystic ovary syndrome (PCOS) and obesity are associated with cardiovascular disease, but it is unclear to what extent they contribute independently. Arterial stiffness might link obesity and PCOS to cardiovascular diseases. Our objective was to investigate whether PCOS in the presence or absence of obesity is linked with arterial stiffness. We conducted a cross-sectional study, including 31 obese (18 with PCOS) and 39 lean (22 with PCOS) women. Estimates of arterial stiffness were obtained by ultrasonography (distensibility and compliance of carotid, femoral, and brachial arteries; carotid elastic modulus; and intima-media thickness) and pulse wave transit time analyses (carotid-femoral pulse wave velocity and aortic augmentation index). Obese women, with or without PCOS, had stiffer arteries than lean women. After adjustment for 24-h mean arterial pressure and age, obesity was inversely associated with the femoral, brachial, and carotid distensibility coefficients [β (95% confidence interval), -0.354 (-0.614 to -0.094), -0.354 (-0.547 to -0.161), and -0.248 (-0.370 to -0.126) 10(-3)/kPA, respectively] and with the femoral and carotid compliance coefficients [-0.296 (-0.563 to -0.029) and -0.190 (-0.377 to -0.003) mm(2)/kPA, respectively] but not with the brachial compliance coefficient [-0.018 (-0.052-0.015) mm(2)/kPA], Young's elastic modulus [0.049 (-0.005-0.103) kPA], aortic pulse wave velocity and aortic augmentation index [0.050 msec (-0.959-1.058 msec) and -1.831% (-8.196-4.534%), respectively]. Analyses with waist circumference as key independent variable gave broadly similar results. In contrast, PCOS was not associated with arterial stiffness estimates after adjustment for the presence of obesity. In young obese women with PCOS, (central) obesity, rather than PCOS itself, is associated with increased arterial stiffness. These data emphasize that, from the perspective of cardiovascular risk reduction, the focus should be on central fat mass reduction in obese women with PCOS.

Acute effects of supramaximal exercise on carotid artery compliance and pulse pressure in young men and women

The purpose of this study was to determine the cumulative effects of repeated cycling sprints (Wingate tests) on carotid compliance and blood pressure (BP). Fourteen young, healthy men and women completed this study. Vascular and hemodynamic measurements were taken at rest, 5 min following a first Wingate test, 25 min following the first Wingate test, 5 min following a second Wingate test, and 25 min following the second Wingate test. At each time point, the measurements taken included brachial and carotid pulse pressure (PP), heart rate, carotid artery maximum and minimum diameters, and carotid compliance. Carotid BP was obtained with applanation tonometry. Carotid diameters were obtained using ultrasonography and compliance was calculated from carotid diameters and BP. Carotid and brachial PP increased significantly (P < 0.05) 5 min after each Wingate test and returned to near baseline 25 min after each Wingate test. No cumulative PP effects were seen. A cumulative effect was seen for carotid compliance: 5 min following the second sprint, carotid arterial compliance decreased significantly more than 5 min following the first sprint (P < 0.05). A single cycling sprint reduces carotid artery compliance immediately after exercise. Performance of a second identical cycling sprint further compounds this vascular change, reducing carotid artery compliance beyond levels seen following a single cycling sprint.

Noninvasive measures of vascular health are reliable in preschool-aged children

Measures of vascular health are known to be important predictors of cardiovascular disease in adulthood. The reliability of commonly used measures of vascular health has been demonstrated in school-aged children, adolescents, and adults; however, their reliability in preschool-aged children remains to be determined. Twenty 2- to 6-year-old children participated in 2 identical testing sessions on different days. Following 10 min of supine rest, carotid artery blood pressures and common carotid artery images were assessed simultaneously for 10 heart cycles, using applanation tonometry and B-mode ultrasound, respectively, while electrocardiogram (ECG) and infrared measures of arterial pressure waves at the dorsalis pedis were recorded continuously. Brachial artery blood pressures were determined using an automated oscillometric device. Carotid artery diameters and intima-media thickness (IMT) were analyzed using a semiautomated detection software program. Carotid compliance, distensibility, and stiffness index were calculated from carotid diameters and carotid blood pressures. Whole-body pulse-wave velocity (PWV) was determined from the time delay between the R spike of the ECG and the foot of the dorsalis pedis arterial pressure wave. Reliability of all measures was assessed using the coefficient of variation (CV) and the intraclass correlation coefficient (ICC). The most reliable measures were carotid artery IMT and PWV with CVs of 2.6% and 3.5% and ICCs of 0.86 and 0.76, respectively. The lower reliability of carotid compliance and distensibility (ICC≤0.63) is likely attributable to the variability of blood pressure measurements. This study confirms that vascular measurements demonstrate substantial reliability in preschool-aged children as young as 2 years.

Serum amyloid A is independently associated with metabolic risk factors but not with early atherosclerosis: the Cardiovascular Risk in Young Finns Study

Serum amyloid A (SAA) is a sensitive marker of inflammation and its elevation has been implicated in obesity and in cardiovascular disease, yet data on its regulation in young adults or on its role in early atherosclerosis is scarce. We investigated which factors explain the variation in SAA and analysed whether SAA could be associated with preclinical atherosclerosis. Serum amyloid A levels were measured in participants of the Cardiovascular Risk in Young Finns Study (n = 2280, n = 1254 women, n = 1026 men). Correlates and determinants of SAA were analysed and the effect of SAA on subclinical atherosclerosis, measured as intima-media thickness (IMT) and carotid artery compliance, was evaluated with risk-factor adjusted models. Serum amyloid A correlated directly and independently of BMI with C-reactive protein (CRP), waist circumference and leptin in both sexes, with total cholesterol, LDL cholesterol and ApolipoproteinA1 (ApoA1) in women and with triglycerides, insulin levels and insulin resistance in men. Use of combined oral contraceptives and intrauterine device was also associated with SAA levels. Determinants for SAA included CRP, leptin and ApoA1 in women, and CRP, leptin and HDL cholesterol in men. SAA levels correlated with carotid compliance in both sexes and with IMT in men, yet SAA had no independent effect on IMT or carotid compliance in multivariable analysis. Serum amyloid A was associated with several metabolic risk factors but was not an independent predictor of IMT or carotid artery compliance. Further longitudinal studies will show whether SAA holds a prognostic value as a risk marker, analogously to CRP.

Assessment of Carotid Compliance Using Real Time Vascular Ultrasound Image Analysis in Marfan Syndrome

Fibrillin-1 deficiency, dysregulated cytokine transforming growth factor-beta, and increased collagen deposition related to fibrillin-1 gene mutations could predispose to impaired carotid compliance (CC) in Marfan syndrome (MFS). We sought to detect any alterations in CC using the vascular image analysis system (VIA). Thirty-two MFS patients, 20 men and 12 women (mean age 34.2 +/- 12.05 years), and 29 controls matched for age, sex, and body surface area (BSA) were recruited. The entire length of each carotid system was initially scanned longitudinally using a 14 MHz linear transducer. Then, a stereotactic clamp held the transducer in contact with the carotid artery. Arterial diameter changes during the cardiac cycle were recorded for 1 minute from both right (RCCA) and left common carotid arteries (LCCA) separately using the VIA system. RCCA and LCCA compliance and distensibility measurements were significantly reduced in MFS patients when compared to controls, P < 0.05. RCCA and LCCA intima-media thickness did not differ between patients and controls, P > 0.05. MFS diagnosis and age were associated with reduced CC in both carotid arteries after adjusting for variables such as, sex, BSA, heart rate, beta-blockade, intima-media thickness, and aortic root size. Our findings showed a reduction in CC in adult patients with MFS. This could be attributed to fibrillin-1 deficiency resulting in structural abnormalities in the carotid arterial wall.

Effect of age and sex on carotid intima-media thickness, elasticity and brachial endothelial function in healthy adults: The Cardiovascular Risk in Young Finns Study

The objective was to produce reference values and to analyse the associations of age and sex with carotid intima-media thickness (IMT), carotid compliance (CAC), and brachial flow-mediated dilatation (FMD) in young healthy adults. We measured IMT, CAC, and FMD with ultrasound in 2265 subjects aged 24-39 years. The mean values (mean +/- SD) in men and women were 0.592 +/- 0.10 vs. 0.572 +/- 0.08 mm (P < 0.0001) for IMT, 2.00 +/- 0.66 vs. 2.31 +/- 0.77%/10 mmHg (P < 0.0001) for CAC, and 6.95 +/- 4.00 vs. 8.83 +/- 4.56% (P < 0.0001) for FMD. The sex differences in IMT [95% confidence interval (CI) for sex difference -0.013 to 0.004 mm, P = 0.37] and CAC (-0.01 to 0.18%/10 mmHg, P = 0.09) became non-significant after adjustments with risk factors and carotid diameter. In FMD, the sex difference was unaltered after adjustments for risk factors, but was reversed after adjustment with brachial diameter (95% CI 0.18-1.32%, P < 0.01). With aging, IMT increased 5.7 +/- 0.4 microm/year and CAC decreased 0.042 +/- 0.003%/10 mmHg/year. The association of age with IMT and CAC was slightly attenuated (12 and 22%, respectively) after adjustments with risk factors, but remained significant (both P < 0.0001). Aging was not significantly related to brachial FMD (P = 0.16). Reference values produced in the present study can be utilized in the cardiovascular risk stratification among young people. Sex differences in the markers of subclinical atherosclerosis were mostly explained by differences in risk factors and vessel size. This emphasizes the importance of risk factor control in the prevention of atherosclerosis in young adults.

Abstract 2128: Assessment Of Carotid Compliance Using Real Time Vascular Ultrasound Image Analysis In Marfan Syndrome

Background: The functional abnormalities in aortic root and ascending aorta in patients with Marfan syndrome (MFS) reflect reduced content of fibrillin-1 (FBN1), dysregulated cytokine transforming growth factor-β and increased collagen deposition related to FBN-1 gene mutations. Carotid arteries in MFS possibly have similar alterations which could predispose to impaired carotid compliance (CC). The aim of this study was to detect any CC abnormalities in MFS using the vascular image analysis system (VIA). Methods: Thirty-one unoperated MFS patients, 20 men and 11 women (mean age 34.3 ± 12.2 years) and 29 normal controls matched for age, sex and body surface area (BSA) were recruited. The entire length of each carotid system was initially scanned longitudinally using a 14 MHz linear transducer. A stereotactic clamp was used to hold the transducer in contact with the carotid artery 2cm below the level of the carotid bulb. Changes in the arterial size during the cardiac cycle were continually recorded for 1 min from the right (RCCA) and left common carotid arteries (LCCA) seperately using the VIA system. Results: CC measurements obtained from the RCCA and LCCA showed statistically significant differences between MFS patients and normal controls (RCCC: 0.126 ± 0.008 mm^2.mmHg^−1 vs 0.173 ± 0.007 mm^2.mmHg^−1, p =&lt; 0.001 and LCCC: 0.132 ± 0.007 mm^2.mmHg^−1 vs 0.158 ± 0.007 mm^2.mmHg^−1, p = 0.007). RCCA and LCCA intima-media thickness did not differ between patients and normal controls (RCCA: 0.050 cm ± 0.001 vs 0.050 cm ± 0.001, p &gt; 0.05 and LCCA: 0.050 cm ± 0.001 vs 0.047 cm ± 0.001, p &gt; 0.05). In a multivariate regression analysis after adjusting for age, sex, BSA, β-blockade and systolic blood pressure (SBP), the presence of MFS associated with reduced CC, (RCCC: beta = −0.036, p &lt; 0.001 &amp; LCCC: beta = −0.021, p = 0.019). Sex, BSA and β-blockade showed no effect on CC, whereas age was negatively associated with CC (RCCC: beta = −0.0016, p=0.001 &amp; LCCC: beta = −0.0015, p=0.001). SBP measurements did not differ between the two groups (119 ± 2.09 mmHg vs 114 ± 1.37 mmHg, p &gt; 0.05). Conclusion: Our findings suggest that despite normal intimal thickness, MFS patients have abnormal carotid compliance. This could be attributed to alterations in elastic properties related to FBN1 deficiency.

Carotid artery compliance in users of plant stanol ester margarine

To investigate the effects of stanol ester margarine use in healthy subjects on arterial compliance, endothelial function and intima-media thickness. Case-control study comparing regular stanol ester margarine users to non-users. Occupational health service clinic. We recruited 50 cases and 50 controls (mean age 51+/-8, range 26-65 years). All subjects were non-smokers and the study groups were matched for age and sex. As cases, we invited subjects who had been using regularly (daily) plant stanol ester margarine for a period of 2 years or longer. Non-invasive ultrasound was used to measure carotid artery compliance, carotid intima-media thickness and brachial artery flow-mediated endothelial dependent vasodilatation. The carotid artery compliance was non-significantly higher in cases compared with controls, 1.84+/-1.02 vs 1.58+/-0.76 %/10 mm Hg (P=0.13). The difference in compliance became statistically significant (P=0.04) when the unbalance between the groups in family history of coronary artery disease and years of education were taken into account. There was also a significant dose-response relationship between stanol margarine use and carotid compliance, longer use being associated with higher compliance. Serum lipoproteins, blood pressure, flow-mediated dilation and intima-media thickness values did not differ between cases and controls. These data raise the possibility that regular stanol ester margarine use may be associated with beneficial changes in arterial compliance. Intervention studies are needed to test this hypothesis and to reveal possible mechanisms.

Blood pressure normalization is associated with normal left ventricular mass but not carotid geometry: the ICARe Dicomano Study

While many studies have examined the relation between antihypertensive treatment and ventricular hypertrophy, relatively few data are available regarding changes in arterial structure due to blood pressure reduction. Therefore, we compared normotensive to untreated hypertensive subjects to uncontrolled (treated with elevated blood pressure values) or controlled (treated with normal blood pressure values) hypertensive older subjects. Community-dwellers (age >or= 65 years) of a small town in Italy (Dicomano) underwent extensive clinical examination, echocardiography, carotid ultrasonography, and applanation tonometry. Of the 614 participants, 173 subjects were normotensive; among the hypertensive subjects, 225 were untreated (51%), 177 (40%) were uncontrolled, and only 39 (9%) were controlled. The majority of treated hypertensive subjects were on monotherapy (82%). Subjects with a history of coronary artery disease or stroke were more frequently treated. Controlled hypertensives had left ventricular mass index similar to normotensives but lower than uncontrolled and untreated hypertensives. There were no differences among the three hypertensive groups in carotid artery structure. Only the pressure-independent stiffness index was reduced in the treated hypertensive subjects compared to untreated hypertensives, with no difference between controlled and uncontrolled subjects. In our community-based, older population, antihypertensive treatment was associated with a normal left ventricular mass only when blood pressure was well controlled. In contrast, carotid artery remodeling and atherosclerosis were independent of antihypertensive treatment as well as of achievement of satisfactory blood pressure control. However, antihypertensive treatment was associated with significantly higher carotid compliance even in the absence of detectable changes in carotid structure.

Transposition of Great Arteries Is Associated With Increased Carotid Artery Stiffness

Transposition of great arteries is the consequence of abnormal aorticopulmonary septation. Animal embryonic data indicate that septation and elastogenesis are related events, but human and clinical data are not available. We tested the hypothesis that large artery elastic function was impaired in patients with transposition of great arteries. We studied 34 patients aged 9 to 19 years, 12+/-3 years after atrial switch operation; 14 patients aged 7 to 9 years, 8+/-1 years after arterial switch operation; and 108 healthy control subjects matched for age. Carotid artery diastolic diameter and pulsatile distension were determined by echo wall-tracking; carotid blood pressure was measured by tonometry. Systolic pressure was higher and diastolic pressure was lower in patients than in controls. Patients with atrial and arterial switch repair were compared with their respective controls by 2-factor ANOVA. For patients with atrial switch repair versus control, stiffness index beta was 4.9+/-1.5 versus 3.1+/-1.0 (P<0.001); for patients witch arterial switch versus control, stiffness index beta was 3.8+/-1.1 versus 2.1+/-0.6 (P<0.001). Similar differences were observed for carotid compliance, distensibility, and incremental elastic modulus as well. The interaction term was not significant for any of the elastic variables, indicating that carotid stiffening was a characteristic of the condition and not the consequence of different hemodynamics. Carotid artery is markedly stiffer in patients, suggesting that impaired elastogenesis may constitute part of the congenital abnormality. Since carotid artery stiffness has been established as an independent cardiovascular risk factor, this condition may have consequences in the clinical management of these patients.

Cardiovagal autonomic function in sedentary and trained offspring of hypertensive parents

In young normotensive subjects, parental hypertension is associated with stiffening of the carotid artery and reduction in cardiovagal outflow and baroreflex gain. In subjects without parental hypertension regular exercise training was found to attenuate age-related reduction in carotid compliance and baroreflex gain. The aim of the present study was to test the hypothesis that regular physical activity is associated with better parameters of carotid artery elasticity, increased cardiovagal outflow and higher baroreflex gain in normotensive offspring of hypertensive parents. We studied 98 healthy, sedentary or endurance exercise trained subjects (49 men, 18-27 years of age) with or without family history of hypertension (FH(+) and FH(-), respectively) in a cross-sectional design. In the sedentary group spontaneous baroreflex indices (sequence method and spectral techniques) were lower in FH(+) subjects than in their FH(-) peers, while in trained subjects these indices were not different between FH(+) and FH(-). Furthermore, in the FH(+) group trained subjects had higher baroreflex indices than their sedentary peers, while in the FH(-) group no significant differences were found. Carotid compliance and distensibility coefficient (echo-tracking ultrasound and applanation tonometry) were not different in FH(-) sedentary and trained subjects, but were higher in FH(+) trained subjects as compared to their sedentary peers. Significant but modest relationships were found between spontaneous baroreflex indices and carotid artery elastic parameters across all subjects. Our present data indicate that in subjects with parental hypertension aerobic exercise training is associated with higher levels of cardiovagal outflow and baroreflex gain, which finding, however, is not explained by greater elasticity of the carotid artery.

Central fat mass versus peripheral fat and lean mass: opposite (adverse versus favorable) associations with arterial stiffness? The Amsterdam Growth and Health Longitudinal Study.

Central and peripheral fatness seem to confer opposite (i.e. adverse vs. protective) effects on cardiovascular risk, but how this occurs is not clear. In addition, the role of peripheral lean mass needs to be elucidated. We therefore investigated, in 336 (175 women) 36-yr-old and apparently healthy adults, the relationship between trunk fat, peripheral fat, and peripheral lean mass on the one hand, and estimates of stiffness of three large arteries on the other. Body composition was assessed by dual-energy x-ray absorptiometry. Arterial properties were assessed by ultrasound imaging. We found that 1) trunk fat was positively (i.e. adversely) associated with stiffness of the carotid and femoral arteries, whereas peripheral fat was inversely (i.e. favorably) associated with stiffness of the brachial and the carotido-femoral segment; 2) peripheral lean mass was positively associated with arterial diameter and carotid compliance and inversely associated with stiffness of the carotido-femoral segment; and 3) after adjustment for the other body composition variables, the above-mentioned associations remained, but peripheral fat in addition became, if anything, favorably associated with stiffness of the femoral artery. We conclude that trunk fat is adversely associated with large artery stiffness, whereas some degree of protection is conferred by peripheral fat and lean mass.

Which Parameter Is More Influential on the Development of Arteriosclerosis in Hemodialysis Patients?

Arteriosclerosis is characterized by stiffening of arteries. The incremental elastic modulus (Einc) measurement is a good marker of arterial wall stiffness. Arteriosclerosis is characterized by stiffening of arteries. Metabolic, inflammatory, and hemodynamic alterations cause structural changes and vascular complications in end‐stage renal disease. The aim of the present study was to evaluate the factors that may affect the development of arteriosclerosis by measurement of Einc in hemodialysis (HD) patients. Thirty‐two patients (16 men and 16 women) on chronic HD with a mean age of 42.2 ± 19.3 (range, 15–80) were included in the study. The carotid Einc was measured to determine arteriosclerosis by high‐resolution echo‐tracking system. Einc measurement was calculated from transcutaneous measurements of carotid arterial internal diameter and wall thickness and carotid pulse pressure. Common carotid compliance (CCC) and distensibility (CCD) were determined from changes in carotid artery diameter during systole and simultaneously measured carotid pulse pressure. Serum levels of calcium (Ca), phosphorus (P), parathormone (PTH), ferritin, C‐reactive protein (CRP), predialysis systolic blood pressure (SBP), predialysis diastolic blood pressure (DBP), pulse pressure (PP), age, HD duration, CCC, and CCD were correlated with Einc in all patients. A significant positive correlation was found between Einc and age (r = 0.40, p &lt; 0.02), SBP (r = 0.39, p &lt; 0.02), PP (r = 0.40, p &lt; 0.02), Ca (r = 0.43, p &lt; 0.01), CRP (r = 0.38, p &lt; 0.02). As expected, Einc was correlated inversely with CCD (r = −0.77, p &lt; 0.0001). The correlation between Einc and HD duration, DBP, ferritin, P, PTH, and CCC was not significant. In conclusion, the stiffening of carotid artery in HD patients is related not only to hemodynamic changes (increased SBP and PP) but also to metabolic (increased Ca) and inflammatory (increased CRP) responses. Carotid Einc is an accepted independent risk factor for cardiovascular mortality. Because of the positive correlation between Einc and serum Ca, vitamin D and Ca‐containing P binder should be used carefully in HD patients.

Cross-sectional compliance overestimates arterial compliance because it neglects the axial strain.

A high resolution echo-tracking system permits the calculation of cross-sectional compliance considering vessel diameter variations alone, and assumes that longitudinal movement of the vessel wall due to pulse pressure is negligible. However, using piezoelectric crystals sutured on the adventitia of the vessel wall we demonstrated that arterial length changes up to 5% (mean 2.7%) as a function of pulse pressure. Therefore, cross-sectional compliance seems to provide a limited approximation of the real phenomenon because it neglects axial vessel movement. Axial vessel movement is taken into account when the vessel compliance is calculated according to the principle of continuity of the mass: [equation: see text]. To verify this hypothesis we measured the blood flow gradient through 10 cm long segments of 10 pig carotid arteries (Qin - Qout) and divided it for the derivative of blood pressure over a given time (deltaP/deltat). For the same vessels, we calculated the cross-sectional compliance (CC) using the echo-tracking system (NIUS 02). We found a CC of (5.91 +/- 0.4) x 10(-7) micro m(2)/mm Hg and a segmental carotid compliance or dynamic compliance (C(d)) of (6.21 +/- 0.2) x 10(-8) micro m(3)/mm Hg. The impact of axial strain in calculations of compliance results in a dynamic compliance, which is one order of magnitude smaller than traditionally calculated arterial compliance.

Cross-sectional compliance overestimates arterial compliance because it neglects the axial strain.

A high resolution echo-tracking system permits the calculation of cross-sectional compliance considering vessel diameter variations alone, and assumes that longitudinal movement of the vessel wall due to pulse pressure is negligible. However, using piezoelectric crystals sutured on the adventitia of the vessel wall we demonstrated that arterial length changes up to 5% (mean 2.7%) as a function of pulse pressure. Therefore, cross-sectional compliance seems to provide a limited approximation of the real phenomenon because it neglects axial vessel movement. Axial vessel movement is taken into account when the vessel compliance is calculated according to the principle of continuity of the mass: [equation: see text]. To verify this hypothesis we measured the blood flow gradient through 10 cm long segments of 10 pig carotid arteries (Qin - Qout) and divided it for the derivative of blood pressure over a given time (deltaP/deltat). For the same vessels, we calculated the cross-sectional compliance (CC) using the echo-tracking system (NIUS 02). We found a CC of (5.91 +/- 0.4) x 10(-7) micro m(2)/mm Hg and a segmental carotid compliance or dynamic compliance (C(d)) of (6.21 +/- 0.2) x 10(-8) micro m(3)/mm Hg. The impact of axial strain in calculations of compliance results in a dynamic compliance, which is one order of magnitude smaller than traditionally calculated arterial compliance.

Arterial stiffness increases with deteriorating glucose tolerance status: the Hoorn Study.

Type 2 diabetes (DM-2) and impaired glucose metabolism (IGM) are associated with an increased cardiovascular disease risk. In nondiabetic individuals, increased arterial stiffness is an important cause of cardiovascular disease. Associations between DM-2 and IGM and arterial stiffness have not been systematically investigated. In a population-based cohort (n=747; 278 with normal glucose metabolism, 168 with IGM, and 301 with DM-2; mean age, 68.5 years), arterial stiffness was ultrasonically estimated by distensibility and compliance of the carotid, femoral, and brachial arteries and by the carotid elastic modulus. After adjustment for age, sex, and mean arterial pressure, DM-2 was associated with increased carotid, femoral, and brachial stiffness, whereas IGM was associated only with increased femoral and brachial stiffness. Carotid but not femoral or brachial stiffness increased from IGM to DM-2. Standardized betas (95% CI) for IGM and DM-2, compared with normal glucose metabolism, were -0.06 (-0.23 to 0.10) and -0.37 (-0.51 to -0.23) for carotid distensibility; -0.02 (-0.18 to 0.18) and -0.25 (-0.40 to -0.09) for carotid compliance; -0.05 (-0.23 to 0.13) and 0.25 (0.10 to 0.40) for carotid elastic modulus; -0.70 (-0.89 to -0.51) and -0.67 (-0.83 to -0.52) for femoral distensibility; and -0.62 (-0.80 to -0.44) and -0.79 (-0.94 to -0.63) for femoral compliance. The brachial artery followed a pattern similar to that of the femoral artery. Increases in stiffness indices were explained by decreases in distension, increases in pulse pressure, an increase in carotid intima-media thickness, and, for the femoral artery, a decrease in diameter. Hyperglycemia or hyperinsulinemia explained only 30% of the arterial changes associated with glucose tolerance. Adjustment for conventional cardiovascular risk factors did not affect these findings. IGM and DM-2 are associated with increased arterial stiffness. An important part of the increased stiffness occurs before the onset of DM-2 and is explained neither by conventional cardiovascular risk factors nor by hyperglycemia or hyperinsulinemia.

Which Parameter Is More Influential on the Development of Arteriosclerosis in Hemodialysis Patients?

Arteriosclerosis is characterized by stiffening of arteries. The incremental elastic modulus (Einc) measurement is a good marker of arterial wall stiffness. Metabolic, inflammatory and hemodynamic alterations cause structural changes and vascular complications in end stage renal disease. The aim of the present study was to evaluate the factors that may affect the development of arteriosclerosis by measurement of Einc in hemodialysis (HD) patients. Thirty-two patients (16 men; 16 female) on chronic HD with a mean age of 42.2 ± 19.3 (range: 15–80) were included in the study. The carotid Einc was measured to determine arteriosclerosis by high-resolution echo-tracking system (Acuson Aspen, Acuson Corp., Mountain View, California, USA). Einc measurement was calculated from transcutaneous measurements of common carotid arterial (CCA) internal diameter and wall thickness and carotid pulse pressure. Common carotid compliance and distensibility were determined from changes in carotid artery diameter during systole and simultaneously measured carotid pulse pressure. Common carotid artery stuffiness (Einc) was influenced by age, systolic blood pressure (SBP), pulse pressure (PP), calcium (Ca) and alkaline phosphatase (ALP). The distensibility of CCA was correlated with age, SBP, diastolic blood pressure (DBP), PP, Ca, ALP, and parathormone (PTH). The inflammatory parameter, hs-CRP, was increased with Einc. The mean Einc measurement was found significantly increased in patient receiving vitamin D. In conclusion, the stiffening of carotid artery in HD patients is related not only to hemodynamic changes (increased SBP, PP) but also to metabolic (increased Ca) and to inflammation (increased hs-CRP). Carotid Einc is accepted independent risk factor for cardiovascular mortality. Because of the positive correlation between Einc and serum Ca, vitamin D and Ca containing phosphorus (P) binders should be used carefully.

Arterial calcifications, arterial stiffness, and cardiovascular risk in end-stage renal disease.

To test the predictive values of and independent contributions to cardiovascular and all-cause mortality of various arterial parameters exploring characteristics of the arterial wall at different sites, we studied prospectively 110 stable end-stage renal disease patients on hemodialysis. These parameters involved carotid diameter, carotid intima-media thickness, carotid compliance, carotid distensibility, carotid incremental elastic modulus, aortic diameter, aortic pulse wave velocity, and the presence of arterial calcifications measured at the sites of the carotid artery, abdominal aorta, iliofemoral axis, and legs. The presence of calcifications was analyzed semiquantitatively as a score (0 to 4) according to the number of arterial sites with calcifications. During a follow-up of 53+/-21 months (mean+/-SD), 25 cardiovascular and 14 noncardiovascular deaths occurred. In univariate analysis, the carotid incremental elastic modulus was the most closely related to prognosis. Risk of death increased with the number of vascular sites involved by calcifications. Moreover, information (in terms of prediction) given by carotid elastic incremental modulus was additive to the presence and extent of vascular calcification-related prediction value. Adjusted hazard ratios of all-cause and cardiovascular mortality for an increase of 1 unit in calcification score were 1.9 (95% confidence interval [CI], 1.4 to 2.6) and 2.6 (95% CI, 1.5 to 4.4), respectively (P<0.001 for both). Adjusted hazard ratios of all-cause and cardiovascular mortality for a 1-SD increase in carotid incremental elastic modulus were 1.6 (95% CI, 1.2 to 2.2) and 1.7 (95% CI, 1.2 to 2.4), respectively (P<0.01 for both). The results of this study showed that the presence and extent of vascular calcifications were strong predictors of cardiovascular and all-cause mortality. Carotid incremental elastic modulus gave additional predictive value.

Creatinine clearance, pulse wave velocity, carotid compliance and essential hypertension

The vascular hallmark of subjects with end-stage renal disease is increased arterial stiffness independent of blood pressure, wall stress, and cardiovascular risk factors such as hypertension, plasma glucose and cholesterol, obesity, and tobacco consumption. Whether arterial stiffness and kidney function are statistically associated in subjects with plasma creatinine < or =130 micromol/L has not yet been determined. Material. In 1290 subjects with normal or elevated blood pressure values and plasma creatinine < or =130 micromol/L, subjects were divided into three tertiles according to the calculated creatinine clearance. Blood pressure, aortic pulse wave velocity (PWV), and standard cardiovascular risk factors were determined in parallel. In 112 of the hypertensive subjects, common carotid and radial artery structure and function (high-resolution echo-Doppler techniques) also were measured. From the 1290 subjects, only the low-tertile group presented a significant negative association between PWV and creatinine clearance independently of blood pressure and standard risk factors. This association was stronger in subjects < or =55 years of age. In the 112 hypertensive subjects, carotid compliance was positively correlated to creatinine clearance even after an adjustment for age, gender, and blood pressure. At less than 55 years of age, creatinine clearance represented 20% of the variance of carotid compliance. Such findings were not observed for radial artery compliance. Increased stiffness of central arteries is statistically associated with reduced creatinine clearance in subjects with mild-to-moderate renal insufficiency, indicating that kidney alterations may interact not only with small but also large arteries, and this is independent of age, blood pressure, and standard risk factors.