Changes In Arterial Compliance Research Articles

Ascorbic Acid Selectively Improves Large Elastic Artery Compliance in Postmenopausal Women

The compliance of large elastic arteries in the cardiothoracic region decreases with advancing age/menopause and plays an important role in the increased prevalence of cardiovascular diseases in postmenopausal women. We determined whether oxidative stress contributes to the reduced large elastic artery compliance of postmenopausal women. Carotid artery compliance was measured during acute intravenous infusions of saline (baseline control) and supraphysiological doses of the potent antioxidant ascorbic acid in premenopausal (n=10; 23+/-1; mean+/-SE) and estrogen-deficient postmenopausal (n=21; 55+/-1 years) healthy sedentary women. Carotid artery compliance was 56% lower in postmenopausal compared with premenopausal women during baseline control (P<0.0001). Ascorbic acid infusion increased carotid artery compliance by 26% in postmenopausal women (1.11+/-0.07 to 1.38+/-0.08 mm2/mm Hgx10(-1); P<0.001) but had no effect in premenopausal women (2.50+/-0.25 versus 2.43+/-0.20 mm2/mm Hgx10(-1)). Carotid artery diameter, blood pressure, and heart rate were unaffected by ascorbic acid. In the pooled population, the change in arterial compliance with ascorbic acid correlated with baseline waist-to-hip ratio (r=0.56; P=0.001), plasma norepinephrine (r=0.58; P=0.001), and LDL cholesterol (r=0.54; P=0.001). These results suggest that oxidative stress may be an important mechanism contributing to the reduced large elastic artery compliance of sedentary, estrogen-deficient postmenopausal women. Increased abdominal fat storage, sympathetic nervous system activity, and LDL cholesterol may be mechanistically involved in oxidative stress-associated suppression of arterial compliance in postmenopausal women.

Effects of vasodilation cardiac output measured by PulseCOTM

PulseCOTM (LiDCO Ltd, London, UK) is a continuous cardiac output (CO) monitor using the pulse-contour method. The pulse-contour method was defined as the method to determine CO from characteristics of the arterial pressure waveform. However, the arterial pressure waveform often changes during surgery because of the arterial compliance changes using vasoactive drugs. These factors may induce miscalculation of the CO by PulseCOTM. In the present study, we investigated the effects of vasodilation induced by prostaglandin E1 (PGE1) on CO measured by PulseCOTM in comparison with CO measured by the bolus thermodilution method.

Arterial compliance changes in diabetic normotensive patients after angiotensin-converting enzyme inhibition therapy

Diabetes mellitus (DM) is known to cause increased arterial wall stiffness and increased cardiovascular risk, even in the absence of hypertension. This study was designed to investigate whether use of an angiotensin-converting enzyme (ACE) inhibitor may improve arterial stiffness in normotensive diabetics, using pulse wave velocity (PWV) as a surrogate marker. We studied 42 patients (26 with type 2 DM, aged 56.5 +/- 9 years, 16 with type 1 DM, aged 41.5 +/- 11 years) by measuring PWV at baseline (compared to 15 age- and gender-matched normal subjects) and after 6 months of treatment with perindopril (4 mg/d). At baseline, PWV was significantly higher in DM patients versus controls (13.09 +/- 2.59 v 9.5 +/- 1.6 m/sec, respectively, P < .001). After 6 months, PWV decreased significantly to 11.68 +/- 3.08 m/sec (P < .003) for the whole DM group. However, the results were driven by the change in the younger type 1 DM (from 12.59 +/- 1.59 to 10.35 +/- 2.21 m/sec, P < .001), whereas in the type 2 DM it was insignificant (from 13.37 +/- 3.0 to 12.42 +/- 3.28 m/sec). Blood pressure and other hemodynamic and biochemical parameters remained unchanged. The results demonstrate that ACE inhibition can improve arterial elasticity and hence risk of cardiovascular complications even in normotensive diabetics. This short treatment was effective only in younger patients with type 1 diabetes, suggesting that early initiation of therapy before the onset of advanced structural alterations is likely to be more cardioprotective.

Unfavorable Effects of Resistance Training on Central Arterial Compliance

0379 PURPOSE: A reduction in arterial compliance is an emerging risk factor for cardiovascular disease mortality and morbidity. We determined the effects of resistance (weight) training on carotid arterial compliance using the randomized intervention study design. METHODS: Twenty-eight healthy men aged 20–38 yrs were random1y assigned to exercise intervention (n = 14) or control (n = 14) group. The intervention group underwent supervised whole-body resistance training 3 days/wk for 4 months and detraining for the subsequent 4 months. The control group was instructed not to alter their normal activity levels during the entire study period. RESULTS: There were no significant differences in baseline carotid arterial compliance and betastiffness index (simultaneous carotid ultrasound and applanation tonometry) between the intervention and control groups. In the intervention group, resistance training increased maximal bench press (19%), dead lift (32%), and squat (55%) strength (all p < 0.001). Carotid arterial compliance decreased 19% (0.21 ± 0.02 mm2/mm Hg vs. 0.17 ± 0.01 mm2/mm Hg, mean ± SE) and beta-stiffness index increased 21% (2.12 ± 0.18 U vs. 2.50 ± 0.14 U) after resistance training (all p < 0.05). These changes returned to the baseline levels (0.20 ± 0.01 mm2/mm Hg and 2.24 ± 0.15 U) during the subsequent detraining period, confirming that the changes in arterial compliance was due to the effect of resistance training per se. There were no significant changes in any of the variables in the control group. Femoral arterial compliance (measure of peripheral artery compliance), brachial and carotid blood pressure, and carotid intima-media thickness did not change significantly in both groups. CONCLUSIONS: In marked contrast to the beneficial effect of regular aerobic exercise, resistance training reduces central arterial compliance in healthy men. Considering the recent guidelines that resistance training be incorporated into a preventive and rehabilitative program of overall physical activity, the present findings may have an important implication for exercise prescription.

Plasma volume expansion by albumin in cirrhosis. Relation to blood volume distribution, arterial compliance and severity of disease

Background/Aims: The aim of the study was to investigate the effect of a standard albumin load on blood volume distribution, arterial compliance, and the renin-angiotensin-aldosterone system in patients with different degrees of cirrhosis. Methods: 31 patients with cirrhosis (Child classes A/B/C=8/14/9) received an intravenous infusion of 40 g human serum albumin during a haemodynamic investigation. Results: Whereas plasma- and blood volume increased by 23 and 15%, respectively ( P<0.001), a significant increase in central blood volume was found only in class A patients (+8%, P<0.05), but not in class B or class C patients (+2.7%, not significant (n.s.)). In contrast, arterial compliance only increased significantly in class C patients (+18%, P<0.05), but not in class A or class B patients (+6%, n.s.). Plasma renin activity (PRA) decreased significantly in class C patients (−31%, P<0.05). When all patients were compared, the change in arterial compliance was inversely correlated to the change in PRA ( r=−0.50, P<0.01). Conclusions: Although infusion of albumin does not expand the central blood volume in patients with advanced cirrhosis, the results indicate a significant improvement in the low effective arterial blood volume of such patients, which may be important in the prevention of circulatory dysfunction.

Arterial compliance changes in diabetic normotensive patients after angiotensin converting enzyme inhibition therapy

Arterial compliance changes in diabetic normotensive patients after angiotensin converting enzyme inhibition therapy

Target organ damage and changes in arterial compliance in white coat hypertension. Is white coat innocent?

The aim of this study was to perform an extensive evaluation of target organ status, metabolic abnormalities and hemodynamic alterations in white coat hypertension (WCH). Fifty normotensive (NT), 90 WCH (ambulatory daytime blood pressure <135/85 mmHg) and 101 hypertensive (HT) subjects underwent extensive biochemical, echocardiographic, fundoscopic examination. In a subgroup study, arterial compliance and intima‐media thickness (IMT) were measured by Doppler ultrasound in left common carotid artery. WCH subjects were found to have higher body mass index (BMI) than the NTs (p = 0.042). Left ventricle mass index (LVMI) was greater in the WCHs than the NTs (p < 0.001), but significantly less than the HTs (p < 0.001). Hypertensive retinopathy was observed in the WCHs, but was less severe and rare compared to the HTs (13% vs 27 %). Both WCHs and HTs had high levels of urinary albumin excretion (UAE) (p = not significant). Total cholesterol was higher in WCHs than in the NTs (p = 0.04) The distensibility coefficient (DC) of the WCHs was significantly greater than the HTs (p < 0.01), while significantly smaller than the NTs (p < 0.01). The compliance coefficient (CC) of the WCHs was significantly higher than the HTs (p < 0.01), and significantly less than the NTs (p < 0.01). The IMT in the HTs was significantly higher than the WCHs (0.81 ± 0.05 vs 0.70 ± 0.04 mm; p < 0.001) and the NTs (p < 0.001). The difference between the NTs and the WCHs was not significant. Our data indicate that patients with WCH represent an intermediate group between NTs and sustained HTs where target organ damage and cardiovascular risk is concerned.

Effects of BM-573, a Novel Thromboxane A2 Inhibitor, on Pulmonary Hemodynamics in Endotoxic Shock

Thromboxane A 2 is considered to be partially responsible for the increase in pulmonary vascular resistance observed after endotoxin administration and to participate in proinflammatory reactions. The effects of a novel dual TXA 2 synthase inhibitor and TXA 2 receptor antagonist (BM-573) on pulmonary hemodynamics were investigated in endotoxic shock. 30 mins before the start of a 0.5 mg/kg endotoxin infusion, 6 pigs (Endo group) received a placebo infusion and 6 other pigs (Anta group) received a BM-573 infusion. In Endo group, pulmonary artery pressure increased from 25 ± 1.8 (T0) to 42 ± 2.3 mmHg (T60) (p < 0.05) after endotoxin infusion while, in Anta group, it increased from 23 ± 1.6 (T0) to 25 ± 1.5 mmHg (T60). This difference is due to a reduction in pulmonary vascular resistance in Anta group while pulmonary arterial compliance changes in Endo group remained comparable with the evolution in Anta group. In Endo group, PaO 2 decreased from 131 ± 21 (T0) to 74 ± 12 mmHg (T300) (p < 0.05), while in Anta group, PaO 2 was 241 ± 31 mmHg at the end of the experimental period (T300). These results demonstrate that TXA 2 plays a major role in pulmonary vascular changes during endotoxin insult. Concomitant inhibition of TXA 2 synthesis and of TXA 2 receptors by BM-573 inhibited the pulmonary vasopressive response during the early phase of endotoxin shock as well as the deterioration in arterial oxygenation.

Arterial pulse wave reflection as feedback.

Traditionally, input impedance (Z(in)) has been used to characterize the global dynamic properties of an arterial system independent of properties of the heart. Defined as the relationship of pressure and flow at the entrance of an arterial system, it describes the ability of an arterial system to dynamically impede blood flow. Recently, a new description has been developed that also characterizes the arterial system independent of properties of the heart. Apparent arterial compliance (C(app)) is defined as the dynamic relationship of input pressure and volume stored in an arterial system, and describes the ability of the arterial system to dynamically store blood. Both Z(in) and C(app) are influenced by pulse wave propagation and reflection. However, the functional form of Capp lends itself to describing the arterial system in terms of negative feedback. Pulse wave reflection decreases the pulsatile volume stored (gain) at low frequencies, but increases the range of frequencies (bandwidth) in which the pulsatile volume is determined by total arterial compliance. This paper illustrates, by simple analytical formula, large-scale arterial system modeling, and direct analysis of data, how this conceptualization of reflection offers a new means to interpret changes in arterial system dynamics resulting from changes in arterial compliance.

Model based analysis of the variation in Korotkoff sound onset timeduring exercise

In this study, a minimal mathematical model of the cardiovascular system isused to study the effects of changes in arterial compliance and cardiaccontractility on the onset time of Korotkoff sounds during an auscultatoryprocedure. The model provides blood pressure waveforms in the ventricle, theaorta and the brachial artery. From these waveforms, pre-ejection time, pulsepropagation time and rise time of the blood pressure at the brachial arterycan be computed. The time delay between onset time of ECG Q wave and onsettime of Korotkoff sound is the sum of these three times. Rise time is zero andthe time delay is minimal when the cuff pressure is slightly above thediastolic pressure. This minimum time delay is represented by QKD. Simulationresults suggest that during the Bruce exercise protocol QKD decreases toone-third of its pre-exercise value if the cardiac contractility increasesthreefold. The effect of arterial compliance is not as significant as that ofthe cardiac contractility. From data recorded during an exercise test, it isobserved that QKD decreases considerably as the test load is increased. Weshow in this study that the amount of decrease in QKD can be used as an indexof the amount of increase in cardiac contractility during an exercise ECGtest. Use of signal averaging for reducing the effect of motion artifactsduring an exercise test is also shown to be very instrumental for makingaccurate QKD measurements.

Large and Small Artery Compliance Changes During Hemodialysis

P116 Heart disease is a major cause of morbidity/mortality in hemodialysis (HD) patients. Studies show changes in arterial compliance, independent of BP, predict mortality in HD. Changes in calcium which occur during the HD treatment may contribute to a reduction in arterial compliance during HD. Pulse wave analysis (PWA) via tonometry provides measures of large and small artery compliance. We used PWA to measure changes in compliance during HD treatment. PWA was recorded immediately prior to a HD treatment (Baseline) and midway through the treatment (Mid-dialysis). Large (C1) and small artery compliance (C2), systemic vascular resistance (SVR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were measured. Serum calcium was measured before and during the HD treatment. RESULTS: Six HD patients (3M/3F) whose mean age was 39 ± 17 years, weighing 151.0 ± 29 lbs and the mean height was 68 ± 4 inches were studied. The hemodynamic data is shown in table: all values are expressed as mean ± SD. The results showed a downward trend (C1), and a statisitcally sgnificant reduction (C2) in large and small artery compliance, respectively, with modest statistically insignificant changes in SBP and DBP. The SVR increase was of marginal significance. The calcium level rose significantly. We conclude that PWA detects changes in hemodynamics during HD not evident using conventional BP which may increase cardiac workload and contribute to the high cardiovascular morbidity and mortality in HD patients.

Large and Small Artery Compliance Changes During Hemodialysis

P116 Heart disease is a major cause of morbidity/mortality in hemodialysis (HD) patients. Studies show changes in arterial compliance, independent of BP, predict mortality in HD. Changes in calcium which occur during the HD treatment may contribute to a reduction in arterial compliance during HD. Pulse wave analysis (PWA) via tonometry provides measures of large and small artery compliance. We used PWA to measure changes in compliance during HD treatment. PWA was recorded immediately prior to a HD treatment (Baseline) and midway through the treatment (Mid-dialysis). Large (C1) and small artery compliance (C2), systemic vascular resistance (SVR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were measured. Serum calcium was measured before and during the HD treatment. RESULTS: Six HD patients (3M/3F) whose mean age was 39 ± 17 years, weighing 151.0 ± 29 lbs and the mean height was 68 ± 4 inches were studied. The hemodynamic data is shown in table: all values are expressed as mean ± SD. The results showed a downward trend (C1), and a statisitcally sgnificant reduction (C2) in large and small artery compliance, respectively, with modest statistically insignificant changes in SBP and DBP. The SVR increase was of marginal significance. The calcium level rose significantly. We conclude that PWA detects changes in hemodynamics during HD not evident using conventional BP which may increase cardiac workload and contribute to the high cardiovascular morbidity and mortality in HD patients.

Effects of pravastatin on left ventricular mass in patients with hyperlipidemia and essential hypertension

Left ventricular (LV) mass is a powerful predictor for future cardiovascular events. Epidemiologic studies have shown that hyperlipidemia is associated with higher LV mass. The effects of statin therapy for hyperlipidemia on LV mass have not been studied. To determine the effects of statin therapy on LV mass, we prospectively studied 3 groups of age and body surface area-matched patients: group 1 (n = 20), patients with systemic hypertension and hyperlipidemia treated with pravastatin plus antihypertensive drugs; group 2 (n = 20), patients with hypertension and hyperlipidemia treated with hypertensive agents and diet control alone; and group 3 (n = 20), hypertensive patients with normolipidemia treated with antihypertensive agents. A group of controls without hypertension or hyperlipidemia was used for comparison. Echocardiograms were recorded at baseline and after 6-month therapy. All hypertensive groups showed significant decreases in LV mass index after treatment. Group 1 had the greatest decrease in LV mass and it was significantly higher than in groups 2 and 3. Multivariate analysis revealed that regression of LV mass was significantly correlated only with the use of statins and sex (p = 0.005 and 0.01, respectively, R 2 = 0.47). Linear regression analysis in group 1 showed a significant correlation between changes in arterial compliance and LV mass regression (r = 0.57, p = 0.01). Thus, the addition of a statin may have an additional effect on reducing LV mass, independent of lipid-lowering effects.

Factores relacionados con la distensibilidad arterial en la hipertensión

To find out what variables affect changes in arterial compliance in subjects with hypertension by measuring their pulse wave velocity (PWV). Cross-sectional, descriptive study. Rural health centre. 156 hypertense patients under 76, chosen by simple random sampling from those on the hypertension register. We determined the degree of hypertension, years of evolution, systolic pressure (SBP), diastolic pressure (DBP), body mass index (BMI), glucaemia, whether lipaemia existed, diabetes or glucose intolerance, tobacco habit, age, sex and PWV (measured automatically by computer). We performed multivariate analysis by means of multiple linear regression, with PWV as the dependent variable, and age, SBP, DBP, BMI, years of evolution of hypertension, cholesterol, triglycerides and glucaemia as independent variables. Mean age 62.5 (SD 8.8). 28.2% male. Mean SBP 153 (SD 18.9). Mean DBP 87 (SD 10.3). Mean years of evolution 10.4 (SD 7.4). Mean BMI 31.2 (SD 4.9). Hyperglucaemia 24.4%. Mean glucaemia 111.3 (SD 29). Mean PWV 11.82 (SD 2.37). PWV was above the theoretically normal figures in 69.2% of cases. Multiple linear regression showed that the variables which affected PWV significantly were age, SBP and hyperglucaemia. Arterial compliance can be improved by controlling SBP, given that the other related factors cannot be changed.

Correlation between aortic pulse wave velocity and norepinephrine, epinephrine, aldosterone and plasma renin activity in very elderly subjects and in patients with congestive heart failure.

The expression of cardiovascular disease in older patients results from the interaction between age-related changes and the disease process itself. It is still unclear whether the physiologic and pathophysiologic changes that occur with advanced age accelerate or compound the factors responsible for congestive heart failure (CHF). Whether, and to what extent, arterial compliance is altered in CHF in the elderly is not clear. It is also unknown whether the plasma levels of neurohumoral factors in the healthy elderly and in CHF patients are associated with changes in arterial compliance. The aim of this study was to evaluate the aortic pulse wave velocity (PWV) in the aorta of elderly healthy subjects and CHF patients, and establish the correlation between PWV and plasma levels of norepinephrine, epinephrine, aldosterone, and renin activity. The study group consisted of 63 females aged 70-100 years (mean, 82 years) with CHF, and 15 age-matched healthy women. Aortic PWV in patients with heart failure did not differ significantly from figures in the age-matched healthy group (12.42 m/sec vs 11.86 m/sec). No statistically significant correlations were found between plasma levels of norepinephrine, epinephrine, aldosterone and renin activity, and aortic compliance measured as PWV. These results suggest that age-associated arterial stiffening is a predominant factor in the development of reduced arterial compliance in elderly patients with CHF.

Change in Arterial Compliance as an Early Manifestation of Hypertension

Conclusions: The above findings strongly suggest that measurements of arterial compliance are useful supplements to the routine measurement of blood pressure in the assessment of the structural and functional state of the vasculature. However, efforts to derive benefit from this are frustrated by a lack of consensus regarding the most appropriate techniques and methodologies for determining arterial compliance. Furthermore, some technologies have been granted patent approval and are therefore regarded as trade secrets. This gives the unfortunate impression of a ‘black box’ approach to the measurement of arterial compliance, without full disclosure of all the analytical steps involved. Despite the differing technologies that are available for measuring arterial compliance, the fact that all have almost consistently shown diminished arterial compliance to be associated with both borderline and established hypertension adds further credence to these findings. It may not be so important that the technologies ...

Change in arterial compliance as an early manifestation of hypertension

Change in arterial compliance as an early manifestation of hypertension

Invariance of the resistance to venous return to carotid sinus baroreflex control.

Despite the well-established fact that the carotid sinus baroreflex system has profound control over the physical properties of the systemic circulation, the resistance to venous return (RVR) seems to be invariant of such control. We hypothesized that this apparent paradox may be explained from the baroreflex changes in systemic arterial compliance. In 12 pentobarbital-anesthetized mongrel dogs, RVR was measured at controlled carotid sinus pressures (CSP) of 50 and 200 mmHg with normal and artificially increased arterial compliance. Arterial compliance was determined from the arterial pressure decay when systemic blood flow was stopped with total vena caval occlusion. Changing CSP between 50 and 200 mmHg changed RVR significantly only under the condition of artificially increased arterial compliance. A four-parameter lumped model of the systemic circulation revealed that the baroreflex changes in arterial compliance and arterial resistance, which occurred in opposite directions, prevented a change in RVR when CSP was changed. The data also suggested that approximately 75% of RVR was attributed to large and conduit veins, the resistances along which were insensitive to baroreflex control. We concluded that the invariance of RVR results from a combination of 1) baroreflex change in the arterial compliance, 2) baroreflex insensitivity of the resistance along large and conduit veins, and 3) spatially distinct location between the major site of reflex change in capacitance and the major site of compliance.

Arterial compliance in hypertension and diabetes mellitus.

Alterations in the structure and function of large and small arterial vessels occur in hypertension and diabetes mellitus. These changes influence the tone and reactivity of the arteries, accelerate the atherogenic process and account for the vascular complications associated with the diseases. The widespread changes throughout the systemic circulation associated with hypertension and diabetes mellitus can alter the compliance characteristics of the arterial blood vessels. Changes in arterial compliance can influence blood pressure, cardiac output and the impedance to left ventricular ejection. The altered compliance characteristics of the blood vessels may represent a marker for early vascular damage that could ultimately predispose to major vascular events. In providing a more direct measure of the effects of disease on vessel wall characteristics, changes in arterial compliance may identify subgroups of patients at high risk of developing future disease-related complications. They may also act as a sensitive parameter to assess the effects of therapeutic interventions on arterial structure and tone.

Arterial wave propagation phenomena, ventricular work, and power dissipation.

The effects of wave propagation phenomena, namely global reflection coefficient (gamma G[omega]) and pulse wave velocity (Cph), are studied in a model of the coupled left ventricle/arterial system. The left ventricle consists of a time-varying elastance, while the arterial system is modeled as a single, uniform, elastic tube terminating in a complex load. Manipulation of model parameters allowed for the precise control of gamma G(omega) and Cph independent of each other, peripheral resistance, and characteristic impedance. Reduction of gamma G(omega) and Cph were achieved through increases in load compliance and tube compliance, respectively. The equations describing the system were solved for left ventricular and aortic pressures and aortic flow. From these, stroke volume (SV), left ventricular stroke work (SW), and steady (Ws), oscillatory (Wo), and total power dissipation (Wt) in the arterial system were calculated. An index of arterial system efficiency was the ratio Wo/Wt (%Wo), with lower values indicating higher efficiency. Reduction of gamma G(omega) yielded initial increases in Ws, while Wo increased for the entire range of gamma G(omega), resulting in increased %Wo. This reduced efficiency is imposed on the ventricle, resulting in increased SW without increased SV. On the other hand, decreased Cph yielded in a steady increase in Ws and a biphasic response in Wo, resulting in reduced %Wo for most of the range of reduced Cph. These results suggest that differential effects on arterial system efficiency can result from reductions of gamma G(omega) and Cph. In terms of compliance, changes in arterial compliance can have different effects on efficiency, depending on where the compliance change takes place. Reasons for these results are suggested, and the role of distributed compliances is raised as a new problem.