Determinants of arterial stiffness in Chinese migrants to Australia

Arterial stiffness, not systolic blood pressure, increases with age in native Papuan populations

Systolic blood pressure (SBP) and arterial stiffness are closely related and may behave reciprocally as cause or effect, interacting in a vicious cycle. Both SBP and arterial stiffness increase with age in populations in most developed countries. However, the age-related increase in SBP appears to be absent in indigenous populations, partially because of their lifelong low-sodium and high-potassium diets, whereas age-related arterial stiffening in these populations remains to be determined. We performed a field survey of the indigenous population of Soroba, a small village located in the central highlands of Papua, Indonesia. Blood pressure levels and brachial-ankle pulse wave velocity (baPWV) were measured using an automatic device. A total of 125 native Papuans 16-75 years of age (59% women) were included in this study. SBP and pulse pressure were not correlated with age. However, diastolic and mean arterial pressure levels increased with age. The prevalence of hypertension was 5% (n = 6; all women), and baPWV significantly increased with age. Compared with participants 45 years of age and older, those younger than 45 years had a higher body mass index (BMI) and spot urine sodium-to-potassium ratio but lower baPWV; however, SBP was not different between these age groups. Multivariate linear regression analysis revealed that SBP was independently associated with baPWV, sex and BMI but not with age; baPWV was independently associated with SBP, age, BMI, sex and heart rate. SBP and baPWV were closely related, but the age-related changes in these measurements differed in this highland Papuan population.

Vascular stiffness and aging in HIV

Large artery stiffening is a biological index of vascular aging. Vascular aging and atherosclerosis are two closely linked processes that develop in parallel and in synergy, sharing common aetiological determinants. Vascular stiffening increases left ventricular work and can lead to diminished coronary perfusion, and may therefore contribute to the development of cardiovascular disease. There is emerging evidence that large artery stiffness and vascular aging are accelerated in HIV infection because of the high prevalence of cardiovascular risk factors among HIV-infected patients. Moreover, the biological effects of HIV and the metabolic perturbations associated with antiretroviral therapies appear to accelerate vascular stiffening in HIV-infected patients. Further studies evaluating the effects of general and targeted therapies and various combinations of antiretroviral therapies on measures of large artery stiffness are urgently needed.

Factors related to pulse wave velocity and augmentation index in chronic hemodialysis patients

BACKGROUND

Augmentation index (AIx) and pulse wave velocity (PWV) are early markers of atherosclerotic vascular changes and also have been shown to be predictive of cardiovascular disease and total mortality. The aim of our study was to evaluate the relationship between PWV and AIx-HR75, which is the corrected form of AIx according to a heart rate of 75 beats/min, echocardiographic parameters and biochemical parameters in chronic hemodialysis (HD) patients.

SUBJECTS AND METHODS

AIx-HR75 and PWV were measured in 556 HD patients by applanation tonometry using the SphygmoCor device.

RESULTS

The mean PWV and AIx-HR75 values of the study group were 10.2 ± 2.4 and 28.4 ± 10.2 m/s. A positive correlation was found between PWV and AIx-HR75 (r = 0.214, p = 0.000). AIx-HR75 correlated with age (r = 0.093, p = 0.028), body surface area (BSA) (r = -0.194, p = 0.000), mean arterial pressure (MAP) (r = 0.335, p = 0.000), pulse pressure (PP) (r = 0.212, p = 0.000), cardiothoracic index (r = 0.155, p = 0.016), and presence of left ventricular hypertrophy (r = 0.152, p = 0.001). PWV correlated with MAP (r = 0.208, p = 0.000), PP (r = 0.098, r = 0.021), left ventricular mass (r = 0.105, p = 0.023), and predialysis sodium level (r = -0.105, p = 0.023). In the multivariate analyses, PWV was associated with MAP (t = 3.78, p = 0.000), presence of diabetes (t = 3.20, p = 0.001), and predialysis sodium level (t = -2.06, p = 0.040), and AIx-HR75 was associated with age (t = 2.48, p = 0.014), female sex (t = 3.98, p = 0.000), BSA (t = -2.15, p = 0.033), and MAP (t = 7.02, p = 0.000).

CONCLUSION

There is a strong association between MAP and arterial stiffness parameters in HD patients. We feel that efficient control of blood pressure could lead to reduced arterial stiffness in HD patients.

Effects of salt substitute on pulse wave analysis among individuals at high cardiovascular risk in rural China: a randomized controlled trial

Reduced-sodium, increased-potassium salt substitutes lower blood pressure but may also have direct effects on vascular structure and arterial function. This study aimed to test the effects of long-term salt substitution on indices of these outcomes. The China Salt Substitute Study was a randomized, controlled trial designed to establish the effects of salt substitute (65% sodium chloride, 25% potassium chloride, 10% magnesium sulfate) compared with regular salt (100% sodium chloride) on blood pressure among 600 high-risk individuals living in six rural areas in northern China over a 12-month intervention period. Data on central aortic blood pressure, aortic pressure augmentation (AUG), augmentation index (AIx), the differences of the peak of first and baseline waves (P(1)-P(0)) and pulse wave reflection time (RT) were collected at randomization and at the completion of follow-up in 187 participants using the Sphygmocor pulse wave analysis system. Mean baseline blood pressure was 150.1/91.4 mm Hg, mean age was 58.4 years, 41% were male and three quarters had a history of vascular disease. After 12 months of intervention, there were significant net reductions in peripheral (7.4 mm Hg, P=0.009) and central (6.9 mm Hg, P=0.011) systolic blood pressure levels and central pulse pressure (4.5 mm Hg, P=0.012) and correspondingly there was a significant net reduction in P(1)-P(0) (3.0 mm Hg, P=0.007), borderline significant net reduction in AUG (1.5 mm Hg, P=0.074) and significant net increase in RT (2.59 ms, P=0.001). There were no detectable reductions in peripheral (2.8 mm Hg, P=0.14) or central (2.4 mm Hg, P=0.13) diastolic blood pressure levels or AIx (0.06%, P=0.96). In conclusion, over the 12-month study period the salt substitute significantly reduced not only peripheral and central systolic blood pressure but also reduced arterial stiffness.

HEREDITARY AND ENVIRONMENTAL INFLUENCES ON ARTERIAL FUNCTION

1. With the ageing population and increasing heart failure, arterial function has been shown to contribute to cardiovascular risk because of its adverse effects on ventriculovascular coupling. Population studies have confirmed independent prognostic information of arterial stiffening on cardiovascular survival. 2. The term 'arterial function' encompasses a range of phenotypes, including measures of arterial structure/remodelling, measures of arterial wall mechanics, surrogate measures of stiffness and of wave reflection. There exists significant interaction between these measures and none is truly independent of the others. Added to this complexity is the recognition that, although arterial function has a strong genetic component, quantification requires a range of techniques from twin to family and population studies. 3. The contribution of heritability is often derived from statistical models with input from genomic scanning and candidate gene studies. Studies to date confirm a significant heritable component for the majority of phenotypes examined. However, it has also been recognized that the factors involved in blood pressure maintenance are likely to be separate to those in arterial structural degeneration with ageing. Candidate genes for arterial function go beyond those of the sympathetic and renin-angiotensin systems and include genes involved in signalling pathways and extracellular matrix modulation. 4. The present review examines the evidence for heritability of the major arterial function phenotypes with environmental and ageing modulation. A brief overview of the impact of atherosclerotic risk factors on arterial function is included.

The Atherosclerosis Risk in Young Adults (ARYA) study: rationale and design

INTRODUCTION

Despite recent advances in treatment, cardiovascular disease (CVD) is still health problem number one in western societies. Aiming at specific prevention strategies for high-risk individuals and shifting the available prevention programs towards younger age groups might increase the success of primary prevention. However, before addressing age-specific prevention programs, more insight in the determinants of early vascular damage and increased cardiovascular risk is warranted as well as insight in determinants increased cardiovascular risk, including vascular damage, at an early age. The Atherosclerosis Risk in Young Adults (ARYA) study was specifically designed to address this issue.

OBJECTIVES

The ARYA study started off with studies evaluating (1) whether it is possible to predict cardiovascular risk at young adulthood by routinely measured adolescent data, and (2) evaluating the role of birth characteristics and adolescent characteristics to the development of vascular damage at young adulthood.

METHODS

The ARYA study comprises of two cohorts of young adults. The Utrecht cohort includes 750 young adults, aged 27-30 years. The Hague-cohort includes 261 young adults born between 1963 and 1968. Data on birth characteristics, growth in early infancy as well as adolescent anthropometry, blood pressure, lipids, body mass index were obtained from the original medical records of the Municipal Health Service. In 1999/2001, the extent of subclinical vascular damage was measured using carotid wall thickness and aortic stiffness. Also, data on adult cardiovascular risk profile, bone density and central blood pressure were assessed, fasting blood was drawn and timed overnight urine samples were collected.

CONCLUSION

The ARYA study is aimed to provide data on early determinants of cardiovascular risk, including vascular damage, at an early age. This knowledge enhances the understanding of atherosclerosis development and CVD risk and is needed to improve the available primary prevention programs.

Adolescent blood pressure does not predict aortic stiffness in healthy young adults. The Atherosclerosis Risk in Young Adults (ARYA) study

BACKGROUND

Increased arterial stiffness has been shown to be a good predictor of cardiovascular morbidity and mortality and to be associated with an adverse cardiovascular risk profile.

OBJECTIVE

To evaluate the relationship between adolescent blood pressure and aortic stiffness in 524 healthy young adults aged 27-30 years, as a means of investigating early determinants of arterial stiffness.

SETTING

General community.

PARTICIPANTS

We studied 524 healthy young adults, aged 27-30 years, who attended secondary school in Utrecht, The Netherlands.

MEASUREMENTS

Data on adolescent weight, height, blood pressure and stage of puberty were available from the original school health records of the Municipal Health Service. At young adulthood, a questionnaire on cardiovascular risk factors was completed and a fasting blood sample was drawn.

MAIN OUTCOME MEASURE

Arterial stiffness, assessed by carotid-femoral pulse wave velocity (PWV).

RESULTS

Adolescent blood pressure did not predict aortic PWV at young adulthood (linear regression coefficient 0.03 m/s per 10 mmHg increase in systolic blood pressure; 95% confidence interval 0.09 to 0.14). Repeated analysis in a subgroup (n = 199) for whom two adolescent blood pressure measurements were averaged showed stronger (2-19x) associations with adult PWV, although these were not significant.

CONCLUSION

Adolescent blood pressure did not predict arterial stiffness in healthy young adults. Measurement error in the baseline blood readings (regression to the mean phenomenon) may partly explain the lack of association in our study. Further studies should confirm our results in order to enable better understanding of the role of adolescent blood pressure in the aetiology of vascular damage.

Simvastatin improves arterial compliance in the lower limb but not in the aorta

Several cardiovascular risk factors adversely affect arterial compliance or the distensibility of large arteries. The role of raised low-density lipoproteins (LDL) cholesterol is uncertain, most studies having shown little effect. We, therefore, investigated whether lowering LDL would improve arterial compliance. Twenty hypercholesterolemic subjects (LDL cholesterol 4.95+/-1.11 mmol/l) were randomized to simvastatin (20 or 40 mg daily) or placebo, each for 4 weeks. Arterial function was assessed at the end of the placebo and simvastatin periods, systemic arterial compliance (SAC) and pulse wave velocities (PWV) centrally (aorto-femoral) and peripherally (femoral-posterior tibial).

RESULTS

Lipoproteins (LDL) cholesterol was reduced similarly with 20 and 40 mg simvastatin (ten subjects each dose) and data were pooled. Lipoproteins (LDL) cholesterol fell 39%, plasma triglyceride fell 18% and high-density lipoprotein (HDL) cholesterol rose 12%, all significant. Systemic arterial compliance (SAC) and central PWV did not change significantly but peripheral PWV showed evidence of greater compliance after simvastatin (10.1+/-1.3 vs. 9.4+/-1.3 m/s with placebo and simvastatin, P<0.03), distensibility being inversely related to PWV. Improvement in PWV was greatest in those with poorest baseline values, r=0.50; P<0.02.

CONCLUSION

Peripheral PWV was alone improved with LDL lowering probably because of the muscularity of that arterial bed; central PWV and SAC (in the elastic aorta) were not influenced.

The prediction of body composition in Chinese Australian females

OBJECTIVE

To determine the efficacy of applying specific body composition techniques to, and assess the relationship between body mass index (BMI) and body fat levels for Chinese Australian females.

DESIGN

Statistical comparative analysis of body composition techniques.

SUBJECTS

Australian resident females of Chinese extraction (n=40) (aged 18-45 y, mean 32.5+/-8.0; BMI range 15.7-30.9 kg/m2, mean 21.7+/-3.1 kg/m2, median 20.8 kg/m2).

MEASUREMENTS

Body composition determined using bio-electrical impedance analysis (BIA), the skin-fold equations of Durnin and Womersley (D&W) and a deuterium dilution technique. Body size was calculated as the body mass index (BMI) weight/height(2) (kg/m2).

RESULTS

With a median BMI of 20.8, range 15.7-30.9, an acceptable BMI existed for 87.5% of the subjects (mean (s.d.) 21.7+/-3.1 kg/m2). Percentage fat mass (%FM) from the deuterium dilution technique (mean (s.d.) 35.6+/-6.4) suggested 75% were overweight or obese. %FM from the D&W equation (mean (s.d.) 28.0+/-3.9) and BIA (mean (s.d.) 29.4+/-5.1) also indicated a tendency towards overweight or obese. The deuterium technique was significantly correlated and significantly different to the D&W eqn, r=0.71 P=0.001; and BIA, r=0.77, P=0.001. Bland and Altman analysis indicated that bias existed between the techniques (BIA mean (s.d.)-6.7+/-4.1) and D&W equation mean (s.d.)-6+/-4.5) when compared to the deuterium method.

CONCLUSIONS

Despite a low mean BMI, body fat levels determined by the three methods suggested that, overall, an unsatisfactory body composition existed. The levels of overweight and obesity (%FM>30) were higher than reported in previous research despite a mean BMI lower than the Australian national average. Comparative analysis suggested that the body fat prediction techniques used may be precise but not accurate. Comparative results obtained for the BIA and D&W equation techniques suggest an overestimation of body fat levels for leaner individuals and under estimation for overfat individuals. The results support the notion that accurate determination of body composition and the determination of appropriate body size may require equations developed for specific ethnic populations.

Diet high in monounsaturated fat does not have a different effect on arterial elasticity than a low-fat, high-carbohydrate diet

OBJECTIVE

To compare the effects of a modified-fat diet high in monounsaturated fat, and a low-fat/high-carbohydrate diet on arterial elasticity.

DESIGN

Randomized crossover design; each diet period was 1 month and a 2-week wash out period occurred in between.

SUBJECTS/SETTING

Thirty healthy, free-living, nonsmoking men and women were recruited from the Melbourne, Australia, metropolitan region of Australia. Men were aged 35 to 55 years and postmenopausal women were aged 50 to 60 years and were not taking hormone replacement therapy. Twenty-eight subjects completed the study.

INTERVENTION

Two diets of equal energy value: a modified-fat diet and a low-fat/high-carbohydrate diet; the modified-fat diet had 3 times more energy from monounsaturated fat.

MAIN OUTCOME MEASURES

Arterial elasticity and serum lipoprotein concentrations.

STATISTICAL ANALYSIS

The general linear model was used to investigate overall effect and any carryover or order effects. Paired t test and the general linear model were used to compare the results from the 2 diet periods.

RESULTS

High-density lipoprotein cholesterol concentration was significantly higher on the modified-fat diet than on the low-fat/low-carbohydrate diet. Arterial elasticity and concentrations of total cholesterol, low-density lipoprotein cholesterol, and triglycerides were not significantly different on the 2 diets.

APPLICATIONS/CONCLUSIONS

There is no evidence to favor a diet high in monounsaturated fat over a low-fat/high-carbohydrate diet because of an effect on arterial elasticity. Other changes in diet may be needed to cause a beneficial effect on arterial elasticity.

Long-term oestrogen treatment does not alter systemic arterial compliance and haemodynamics in biological males

BACKGROUND

Studies have shown that chronic oestrogen treatment improves both lipid profile and vascular reactivity in postmenopausal women, in whom it also appears to have a beneficial effect on vascular haemodynamics and compliance. Whether oestrogen has a similar effect in men is unknown.

OBJECTIVE

To determine whether long-term oestrogen treatment alters arterial compliance and haemodynamics in biological males.

METHODS

We compared the effects of chronic oestrogen treatment on blood pressure, heart rate and arterial compliance in 21 male-to-female transsexuals prescribed long-term oestrogen treatment with those in 20 age-matched healthy males. Systemic arterial compliance was assessed using the 'area method', by the simultaneous measurement of aortic flow and driving pressure.

RESULTS

Mean systemic arterial compliance was similar in transsexuals and age-matched males (mean +/- SE 0.66 +/- 0.06 ml/mmHg compared with 0.58 +/- 0.05 ml/mmHg, P = 0.34). These results did not differ after the exclusion of transsexuals with coronary risk factors or vascular disease. Heart rate (67 +/- 2 beats/min compared with 64 +/- 3 beats/min, P = 0.41), systolic blood pressure (119 +/- 3 mmHg compared with 119 +/- 2 mmHg, P = 0.95), pulse pressure (55 +/- 3 mmHg compared with 50 +/- 2 mmHg, P = 0.13), diastolic blood pressure (64 +/- 2 mmHg compared with 69 +/- 2 mmHg, P = 0.06) and mean arterial pressure (84 +/- 2 mmHg compared with 89 +/- 2 mmHg, P = 0.09) were also similar at baseline between the two groups. Serum testosterone (an index of oestrogen treatment) was markedly suppressed in the transsexuals compared with the males (0.8 +/- 0.5 nmol/l compared with 25.3 +/- 12.6 nmol/l, P < 0.0001). Univariate analysis revealed that the best predictors of arterial compliance were the pulse pressure (rs = -0.41, P = 0.02) and the systolic blood pressure (rs = -0.35, P = 0.02). On multivariate analysis, the best combination of predictors of compliance were the pulse pressure, testosterone and low-density lipoprotein cholesterol concentrations (R2 = 0.29, P = 0.01).

CONCLUSIONS

Although previous evidence suggests chronic oestrogen treatment can improve endothelium-dependent vasodilatation and favourably alter the lipid profile in biological males, these changes are not reflected in changes in systemic arterial compliance. Changes in arterial compliance may not be central to the beneficial effects of oestrogen on vascular function, at least in males.

Vitamin E improves arterial compliance in middle-aged men and women

Diminished arterial compliance, or loss of elasticity in large arteries, is an emerging cardiovascular risk factor with a reversible component that includes improved endothelial function. Vitamin E, which may reduce cardiovascular risk, can lower vascular resistance. Twenty-eight middle-aged men and women were randomized through a double-blind design to 8 weeks of supplemental vitamin E (400 IU daily) or placebo. Compliance was determined non-invasively from simultaneous measurements of aortic flow and carotid pressure at baseline and after 4 and 8 weeks.

RESULTS

arterial compliance increased by 37% at 4 weeks and by 44% at 8 weeks (P = 0.01) only in the vitamin E group and was independent of an effect on arterial pressure. A rise was seen in 12/14 subjects. There was no significant change with placebo (+ 8%).

CONCLUSIONS

short-term vitamin E supplementation improves arterial compliance.

Vascular compliance as a measure of biological age

OBJECTIVES

To determine the measure of vascular compliance most closely related to age.

DESIGN

A review of 22 studies relating aortic compliance to age and a discussion of other factors related to vascular compliance.

MEASUREMENTS

Aortic compliance, elastic modulus, postmortem aortic changes, pulse wave velocity in the aorta, common carotid, lower limb and upper limb.

RESULTS

1. Aortic compliance and carotid artery compliance is closely related to age; 2. Compliance in the peripheral arteries, in 16 reports, appears less closely related to age; 3. There is evidence that aortic compliance is related to hypertension, cardiac function, and left ventricular hypertrophy and can be increased by exercise, hormonal therapy, antioxidant and antihypertensive treatment; and 4. Vascular compliance is more closely related to chronological age than other measures such as skin inelasticity, greying of hair, baldness etc.

CONCLUSIONS

Because of the close relationship between aortic and carotid compliance and chronological age, deviation from the age-predicted norm (biological age) may prove to be a good predictor of cardiovascular pathology.

Estimation of arterial mechanics in clinical practice and as a research technique

1. Large conduit artery pathophysiology is associated with considerable morbidity with even normal ageing, irrespective of concurrent influences, associated with impaired arterial function. 2. Recent technical advances have enabled high-resolution non-invasive assessment of pulsatile arterial properties, but this has been largely confined to more muscular superficial arteries. There has been less study of arterial regions prone to disease that would, theoretically at least, benefit from pharmacological or other intervention to improve function. 3. Based on studies in animal models and, in particular, human arterial segments, specific pharmacological agents have been proposed as improving arterial behaviour. If this is to become a therapeutic target, it behoves increased effort to understand and measure meaningful indices of arterial function and to find ways of assessing response and outcome. 4. A number of different approaches to assessment and quantification of arterial mechanics are available in the literature. The present review compares and discusses some of these different techniques and looks at differences between arterial segments and evidence that appropriate intervention may beneficially modify arterial behaviour. 5. For clinical or research usefulness, assessment of arterial mechanics must provide more information than currently derived from simple numerical measurement of brachial blood pressure. This is particularly true because epidemiological risk evidence is based on brachial rather than central blood pressure recordings. There has been an explosion of work in this field in recent years and the present review does not pretend to reference all relevant material; rather, it tries to provide a broad coverage of the topic and hopes to support the need for continued endeavours in the field of arterial mechanics.

Arterial compliance, blood pressure, plasma leptin, and plasma lipids in women are improved with weight reduction equally with a meat-based diet and a plant-based diet

Obesity, strongly associated with the risk for coronary heart disease (CHD), is becoming increasingly prevalent. This study was designed to establish first whether systemic arterial compliance (SAC), an index of arterial function, is improved with weight loss and second, whether cardiovascular risk factors that improve with weight loss are reduced equally with lean meat or with an equivalent amount of plant protein in the diet. Thirty-six women, mostly overweight or obese, aged 40+/-9 years, were allocated nonrandomly to a 16-week parallel-design trial of two equienergetic diets designed to lead to weight loss, with one arm of the study emphasizing red meat and the other soybeans as the major protein source. Body weight, waist and hip circumference, and plasma lipids, glucose, insulin, and leptin levels were measured, and SAC was calculated from ultrasound measurement of aortic flow velocity and aortic root driving pressure. Subjects lost weight (9% of body weight in 16 weeks) and showed decreased plasma total and low-density lipoprotein (LDL) cholesterol (12% and 14%, P < .0001, respectively), triacylglycerol (17%, P < .05), and leptin (24%, P < .01) concentrations. However, lipoprotein(a) [Lp(a)] levels did not change significantly. Mean arterial pressure (MAP) decreased 7% and SAC increased 28% (P < .001 for both). However, only the decrease in arterial pressure correlated significantly with the reduction in the waist to hip ratio (WHR), and the improvement in SAC correlated inversely with the blood pressure reduction (P < .001 for both). Further, weight loss and the metabolic benefits of weight loss occurred equally with the meat-based and plant-based diets. We conclude that moderate weight loss in women leads to a substantial reduction in the cardiovascular risk, including SAC.

Effect of fish oil supplementation on aortic compliance in rats: role of the endothelium

Arterial compliance improves with dietary fish oils in patients with high cardiovascular risk. Since fish oils alter prostaglandin metabolism and the L-arginine-nitric oxide pathway, and since compliance may be modified by vasoactive substances, the effect of the endothelium and some of its derivatives on aortic complaince were examined. Rats were randomly allocated to four groups, the first of which fed only the regular chow. The remaining three groups were fed the chow supplemented by daily gavage with either coconut, fish or safflower oil for 8 weeks. The thoracic aorta was removed and six 2 mm rings obtained. Rings were paired and one from each pair treated with either N(W)-nitro-L-arginine, indomethacin or de-endothelialized. A diameter-tension curve was initiated from wire touch position using incremental increases in wire distance until no further response observed. The data was transformed to a diameter-pressure relationship and fitted with a linear equation, the slope of which related directly to compliance. De-endothelialization (slopes: control vs de-endothelialized: 9.05+/-0.15 vs 8.31+/-0.24; P< 0.05) and indomethacin (slopes: control vs indomethacin: 9.11+/-0.15 vs 7.76+/-0.37; P< 0.05) significantly decreased arterial compliance as did dietary fish oils (slopes: control vs n-3: 9.16+/-0.11 vs 7.84+/-0.39; P< 0.05). No further effect was seen with indomethacin in the fish oil treated group. It is concluded that the endothelium and in particular, endothelium derived prostanoids, contribute to vessel compliance. We also conclude that fish oils have a similar action to indomethacin, leading to the increase in aortic stiffness observed.

Protective effect of chronic garlic intake on elastic properties of aorta in the elderly

BACKGROUND

Epidemiological studies have suggested that garlic may have protective effects against cardiovascular diseases. We undertook this cross-sectional observational study to test the hypothesis that regular garlic intake would delay the stiffening of the aorta relating to aging.

METHODS AND RESULTS

We studied healthy adults (n=101; age, 50 to 80 years) who were taking > or = 300 mg/d of standardized garlic powder for > or = 2 years and 101 age- and sex-matched control subjects. Pulse wave velocity (PWV) and pressure-standardized elastic vascular resistance (EVR) were used to measure the elastic properties of the aorta. Blood pressures, heart rate, and plasma lipid levels were similar in the two groups. PWV (8.3+/-1.46 versus 9.8+/-2.45 m/s; P<.0001) and EVR (0.63+/-0.21 versus 0.9+/-0.44 m2 x s(-2) x mm Hg(-1); P<.0001) were lower in the garlic group than in the control group. PWV showed significant positive correlation with age (garlic group, r=.44; control group, r=.52) and systolic blood pressure (SBP) (garlic group, r=.48; control group, r=.54). With any degree of increase in age or SBP, PWV increased less in the garlic group than in the control group (P<.0001). ANCOVA and multiple regression analyses demonstrated that age and SBP were the most important determinants of PWV and that the effect of garlic on PWV was independent of confounding factors.

CONCLUSIONS

Chronic garlic powder intake attenuated age-related increases in aortic stiffness. These data strongly support the hypothesis that garlic intake had a protective effect on the elastic properties of the aorta related to aging in humans.

Hormonal therapy increases arterial compliance in postmenopausal women

OBJECTIVES

This study investigated the effects of hormonal therapy on large arterial properties.

BACKGROUND

Arterial stiffness is an emerging risk marker for coronary heart disease and is potentially modifiable. Postmenopausal use of hormonal therapy is associated with a lower risk of coronary heart disease.

METHODS

Total systemic arterial compliance (SAC) and pulse wave velocity (PWV) were determined in 26 premenopausal and 52 postmenopausal women, 26 of whom were taking hormonal therapy.

RESULTS

Arterial compliance was greater in the premenopausal group (mean +/- SEM 0.57 +/- 0.04 arbitrary compliance units [ACU]) than in the postmenopausal group not taking hormonal therapy (0.26 +/- 0.02 ACU, p = 0.001). Postmenopausal women taking hormonal therapy had a significantly increased total SAC compared with women not taking hormonal therapy (0.43 +/- 0.02 vs. 0.26 +/- 0.02 ACU, p = 0.001). PWV in the aortofemoral region in the premenopausal women was 6.0 +/- 0.2 vs. 8.9 +/- 0.3 m/s (p < 0.001) in untreated postmenopausal women. However, postmenopausal women taking hormonal therapy had a significantly lower PWV than those not taking hormonal therapy (7.9 +/- 0.2 vs. 8.9 +/- 0.3 m/s, p = 0.01). Eleven postmenopausal women had their hormone replacement therapy withdrawn for 4 weeks, resulting in a significant decrease in SAC and a significant increase in aortofemoral PWV.

CONCLUSIONS

The increased SAC and decreased PWV in women receiving hormonal therapy suggest that such therapy may decrease stiffness of the aorta and large arteries in postmenopausal women, with potential benefit for age-related cardiovascular disorders. The reduction of arterial compliance with age appears to be altered with hormonal therapy.

Arterial compliance in obese subjects is improved with dietary plant n-3 fatty acid from flaxseed oil despite increased LDL oxidizability

The compliance or elasticity of the arterial system, an important index of circulatory function, diminishes with increasing cardiovascular risk. Conversely, systemic arterial compliance improves through eating of fish and fish oil. We therefore tested the value of high intake of alpha-linolenic acid, the plant precursor of fish fatty acids. Fifteen obese people with markers for insulin resistance ate in turn four diets of 4 weeks each; saturated/high fat (SHF), alpha-linolenic acid/low fat (ALF), oleic/low fat (OLF), and SHF. Daily intake of alpha-linolenic acid was 20 g from margarine products based on flax oil. Systemic arterial compliance was calculated from aortic flow velocity and aortic root driving pressure. Plasma lipids, glucose tolerance, and in vitro LDL oxidizability were also measured. Systemic arterial compliance during the first and last SHF periods was 0.42 +/- 0.12 (mean +/- SD) and 0.56 +/- 0.21 units based on milliliters per millimeter of mercury. It rose significantly to 0.78 +/- 0.28 (P < .0001) with ALF; systemic arterial compliance with OLF was 0.62 +/- 0.19, lower than with ALF (P < .05). Mean arterial pressures and results of oral glucose tolerance tests were similar during ALF, OLF, and second SHF; total cholesterol levels were also not significantly different. However, insulin sensitivity and HDL cholesterol diminished and LDL oxidizability increased with ALF. The marked rise in arterial compliance at least with alpha-linolenic acid reflected rapid functional improvement in the systemic arterial circulation despite a rise in LDL oxidizability. Dietary n-3 fatty acids in flax oil thus confer a novel approach to improving arterial function.