Impact of physical and physiological factors on arterial function

Risk factors for stroke among anthropometric indices and lipid profiles in the Korean population: a large-scale cross-sectional study

Stroke is strongly associated with death and disability. However, the associations between stroke and lipid profiles such as total cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-C), and red blood cells (RBCs) and anthropometric indices such as waist circumference and waist-to-height ratio (WHtR) remain unclear. The objective of this study was to investigate these relationships in a Korean population. This large-scale cross-sectional study included data from 38,190 subjects collected from 2010 to 2018 by the Korea National Health and Nutrition Examination Survey (KNHANES). Simple logistic regression models and multiple logistic regression models were used to evaluate the association of stroke with lipid profiles and anthropometric indices in the crude model, adjusted Model 1, and fully adjusted Model 2. In men, stroke was negatively associated with height, weight, and hematocrit level. Total cholesterol and triglycerides were strongly negatively associated with stroke in Model 2. Creatinine level and stroke were weakly associated. Additionally, height, weight, total cholesterol, triglycerides, and hematocrit and creatinine levels were associated with stroke both before and after adjustment. In women, in Model 2, stroke was positively associated with height, weight, and creatinine level. A strong negative association was found between total cholesterol and stroke. Stroke was negatively associated with hemoglobin level, hematocrit level, and RBCs. Additionally, total cholesterol, hemoglobin level, hematocrit level, creatinine level, and RBCs were associated with stroke both before and after adjustment. Weight and height were more closely associated with stroke than waist circumference and WHtR in Korean men. Our results suggested that the association of stroke with triglycerides, height, and weight differed according to sex and that HDL-C was not associated with stroke in people of either sex.

Eating frequency has an inverse correlation with adiposity measures and non-invasive arterial stiffness parameters in healthy adult people

BACKGROUND

Lifestyle modifications have been recommended as an essential treatment approach for cardiovascular diseases. Recent studies have shown that eating frequency (EF) correlates with hypertension and related risk of organ damage. This study aimed to examine critical clinical implications to evaluate the association of EF with arterial stiffness parameters as an early marker of atherosclerosis manifestations.

METHODS

A cross-sectional descriptive study was performed on 658 participants of the PERSIAN Organizational Cohort study in Mashhad, aged 30-70 years. Arterial stiffness was assessed by measurement markers of arteriosclerosis, including arterial age, augmentation index (AIx), augmentation pressure (AP), carotid-femoral pulse wave velocity (Cf-PWV), and central blood pressure. Differences in anthropometric indices, blood indices, and arterial stiffness parameters were evaluated across EF groups.

RESULTS

Our data demonstrate that EF was positively correlated with total daily energy intake, and favourable profiles of adiposity and blood lipids. Subjects with an increased EF, had significantly lower AIx, AP, Arterial Age and Central blood pressure (P for trend<0.001) as compared to Lowest EF and not significant with PWV (P for trend, 0.19). Arterial stiffness was also significantly lower in those with increased EF compared with subjects with low EF. By Linear regression analysis, after adjustment for Confounding factors, except PWV, EF showed the associations with all of the non-invasive arterial stiffness parameters.

CONCLUSION

Increased EF is associated with a lower wave reflection and blood pressure in the central arteries.

Examining the relationship between arterial stiffness and swim-training volume in elite aquatic athletes

PURPOSE

Factors such as prone body position, hydrostatic pressure, and intermittent breath-holding subject aquatic athletes to unique physical and environmental stressors during swimming exercise. The relationship between exposure to aquatic exercise and both arterial stiffness and wave reflection properties is not well-understood. This study assessed central artery stiffness and wave reflection properties in elite pool-swimmers (SW), long-distance open-water swimmers (OW), and water polo players (WP) to examine the relationship between these variables and aquatic exercise.

METHODS

Athletes competing in SW, OW and WP events at the FINA World Championships were recruited. Carotid-femoral pulse wave velocity, and pulse wave analysis were used to quantify arterial stiffness, and central wave reflection properties.

RESULTS

Athletes undertook differing amounts of weekly swimming distance in training according to their discipline (SW: 40.2 ± 21.1 km, OW: 59.7 ± 28.4 km, WP: 11.4 ± 6.3 km; all p < 0.05). Pulse wave velocity (Males [SW: 6.0 ± 0.6 m/s, OW: 6.5 ± 0.8 m/s, WP: 6.7 ± 0.9 m/s], Females [SW: 5.4 ± 0.6 m/s, OW: 5.3 ± 0.5 m/s, WP: 5.2 ± 0.8 m/s; p = 0.4]) was similar across disciplines for females but was greater in male WP compared to male SW (p = 0.005). Augmentation index (Males [SW: - 3.4 ± 11%, OW: - 9.6 ± 6.4%, WP: 1.7 ± 10.9%], Females [SW: 3.5 ± 13.5%, OW: - 13.2 ± 10.7%, WP: - 2.8 ± 10.7%]) was lower in male OW compared to WP (p = 0.03), and higher in female SW compared to OW (p = 0.002). Augmentation index normalized to a heart rate of 75 bpm was inversely related to weekly swim distance in training (r = - 0.27, p = 0.004).

CONCLUSIONS

This study provides evidence that the central vasculature of elite aquatic athletes differs by discipline, and this is associated with training load.

Short stature is associated with higher pulse wave velocity in subjects without overt cardiovascular disease

Short stature is reportedly associated with cardiovascular disease (CVD). However, the mechanism underlying this intriguing epidemiological finding is unclear. Pulse wave velocity (PWV), a marker of vascular stiffness, is a predictor of future CVD. Therefore, PWV may be affected by height even before overt CVD occurs. Here, we investigated the association between adult height and PWV in subjects without overt CVD.A total of 1019 subjects (48 ± 12 years old; 509 men, 21 with diabetes mellitus, 209 with hypertension) without overt CVD were enrolled, all of whom underwent brachial-ankle PWV (baPWV) measurements. The subjects were divided into 3 groups by height. A multiple regression model was used to estimate baPWV values among heights after the adjustment for confounders.Mean baPWV value was highest in the group with the shortest height for both sexes (both P < .001). Bivariate correlation analysis between height and baPWV showed significant correlations in men (r = -0.131, P = .003) and women (r = -0.180, P < .001). In the multiple regression analysis with adjustment for identified confounders, group height was a predictor of baPWV (P for trend = .003) in younger men (<50 years old) but not in older men, while group height was correlated with baPWV in older women (≥50 years old, P for trend = .014) but not in younger women.Height is inversely correlated with baPWV in subjects without overt CVD, especially in younger men and older women. This may explain the historical epidemiological observation of an inverse relationship between height and CVD.

Insulin Resistance and Renal Sodium Handling Influence Arterial Stiffness in Hypertensive Patients with Prevailing Sodium Intake

BACKGROUND

Insulin resistance and renal tubular sodium handling influence arterial structure and function and play an essential role in salt-sensitive forms of hypertension.

METHODS

In a population with prevailing sodium consumption, we assessed the relationship between cardiovascular phenotypes (peripheral and central blood pressures, elastic properties of large arteries, the left ventricular structure) and sodium handling parameters (daily urinary sodium excretion, fractional urinary lithium excretion in proximal-FELi and distal tubules), as a function of insulin sensitivity-measured by homeostasis model assessment-insulin resistance (HOMA-IR), leptin-to-adiponectin (L/A) ratio, and homeostasis model assessment-adiponectin (HOMA-AD).

RESULTS

In patients with FELi below the median value (corresponding to the group with increased proximal sodium reabsorption) and higher insulin resistance as measured by HOMA-IR, pulse wave augmentation indexes were significantly higher-AIxP (99.4% vs. 86.2%; P = 0.007), AIxC1 (159.4% vs. 144.2%; P = 0.04), and AIxC2 (36.1% vs. 28.3%; P = 0.02), than in patients with lower insulin resistance. The same trend was observed in relation to L/A ratio-AIxP (98.7% vs. 87.1%; P = 0.005), AIxC1 (158.6% vs. 144.5%; P = 0.02), and AIxC2 (35.6% vs. 28.5%; P = 0.01) and HOMA-AD-AIxP (99.7% vs. 83.8%; P = 0.001), AIxC1 (160.5% vs. 140.3%; P = 0.007), and AIxC2 (36.6% vs. 26.3%; P = 0.003). Such relationships were not observed in patients with FELi above the median value.

CONCLUSIONS

In the hypertensive population with prevailing sodium intake, insulin resistance and increased sodium reabsorption in proximal tubules may affect arterial wall function.

Impact of coronary artery disease on augmentation index as measured by estimated central blood pressure: A case control study in Asian Indians

Aims

We compared various components of blood pressure and arterial stiffness of healthy control with those of coronary artery disease (CAD) patients using BP+ machine™.

Methods

In this prospective, case-control study, total 585 individuals of both the genders were enrolled. The study population consisted of 277 controls (healthy siblings of diseased subjects not having CAD – group A) and 308 CAD patients (group B). Age and sex adjusted regression and receiver operative curve (ROC) analysis was performed to assess the strength of association of these parameters.

Results

We found that mean systolic blood pressure (SBP) (137.14 ± 22.49 vs. 129.26 ± 19.86), central systolic blood pressure (CSBP) (130.78 ± 21.89 vs. 117.53 ± 17.98), augmentation index (AI) (108.55 ± 44.98 vs. 49.38 ± 21.03) and pulse rate variability (98.82 ± 231.09 vs. 82.86 ± 208.77) were significantly (p < 0.05) higher in CAD population as compared to healthy counterparts. Left ventricular contractibility as measured by dP/dt was significantly lower in CAD patients. All these parameters were significantly abnormal in CAD as compared to healthy control population irrespective of the gender of the patient except for SBP in females. Both – odds ratio (1.108; 95% CI: 1.081–1.135; p < 0.0001) and ROC analysis (AUC: 0.937; 95% CI: 0.919–0.956; p < 0.0001) showed AI as the strongest predictor of CAD, closely followed by CSBP.

Conclusion

Central aortic blood pressure parameters such as AI and CSBP measured noninvasively with BP+ machine could be the effective predictors of CAD in Asian Indians.

Arterial Stiffness: Going a Step Beyond

Interest in arterial stiffness has been fueled by the scientific and clinical implications of its "vicious cycle" relationship with aging and systolic blood pressure. In physical terms, stiffness is the slope of the relationship between an artery's distending pressure and its cross-sectional area or volume. Pulse wave velocity (PWV, in m/s), the most common arterial stiffness indicator, is usually measured by the foot-to-foot time and distance method and is proportional to [stiffness × area (or volume)]1/2 at a given pressure. Its intrinsic pressure dependency and other flaws in current PWV methods limit its utility. In contrast, the arterial stiffness-arterial pressure relationship is near-linear, with a slope β, the exponent of the curvilinear arterial pressure-arterial volume relationship. The concept of arterial stiffening is related to β and describes a more functionally relevant aspect of arterial behavior: the change in stiffness for a given change in pressure. Arterial stiffening can be estimated from the variability of within-individual BP measurements (24-h ambulatory, home BP, or BP measured at different arm heights) and can be expressed as the pulse stiffening ratio (PSR) = [systolic stiffness]/[diastolic stiffness] or the ambulatory arterial stiffness index (AASI or its symmetric form, sAASI). High arterial stiffness (PWV) and stiffening (β, stiffness index, cardio-ankle vascular index, AASI, and PSR) are associated with increased cardiovascular disease risk, but it remains unclear whether these indicators are useful in improving medical care quality; the standard of care remains stringent BP control.

Review: Clinical assessment of endothelial function — an update

Endothelial dysfunction precedes clinically detectable vascular disease, suggesting its early detection may allow the targeting of treatment to improve endothelial function and thus inhibit progression of disease.1,2 Although the evidence for a preventive strategy remains circumstantial, there is worldwide interest in the measurement of endothelial function in relation to risk factors and treatment of atherosclerotic vascular disease. Unfortunately, a widely applicable clinical measurement of endothelial function does not yet exist; those that are available remain tools for research. The ideal clinical test of endothelial function should be specific, sensitive and reproducible, as well as simple to perform, painless, and inexpensive. In this review we outline the relative merits and disadvantages of the techniques that are available.

Relation of Stature to Outcomes in Korean Patients Undergoing Primary Percutaneous Coronary Intervention for Acute ST-Elevation Myocardial Infarction (from the INTERSTELLAR Registry)

Although epidemiologic studies have shown the impact of height on occurrence and/or prognosis of cardiovascular diseases, the underlying mechanism is unclear. In addition, the relation in patients with ST-segment elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention (PCI) remains unknown. We sought to assess the influence of height on outcomes of patients with acute STEMI undergoing primary PCI and to provide a pathophysiological explanation. All 1,490 patients with STEMI undergoing primary PCI were analyzed. Major adverse cardiac and cerebrovascular events (MACCE) were defined as all-cause mortality, nonfatal myocardial infarction, nonfatal stroke, and unplanned hospitalization for heart failure (HF). Patients were divided into (1) MACCE (+) versus MACCE (-) and (2) first- to third-tertile groups according to height. MACCE (+) group was shorter than MACCE (-) group (164 ± 8 vs 166 ± 8 cm, p = 0.012). Prognostic impact of short stature was significant in older (≥70 years) male patients even after adjusting for co-morbidities (hazard ratio 0.951, 95% confidence interval 0.912 to 0.991, p = 0.017). The first-tertile group showed the worst MACCE-free survival (p = 0.035), and most cases of MACCE were HF (n, 17 [3%] vs 6 [1%] vs 2 [0%], p = 0.004). On post-PCI echocardiography, left atrial volume and early diastolic mitral velocity to early diastolic mitral annulus velocity ratio showed an inverse relation with height (p <0.001 for all) despite similar left ventricular ejection fraction. In conclusion, short stature is associated with occurrence of HF after primary PCI for STEMI, and its influence is prominent in aged male patients presumably for its correlation with diastolic dysfunction.

Predictors of Development of Echocardiographic Left Ventricular Diastolic Dysfunction in the Subjects Aged 40 to 59 Years (from the Oulu Project Elucidating Risk of Atherosclerosis Study)

Factors in the middle age that are associated with the risk for development of diastolic dysfunction in long term are not fully established. The Oulu Project Elucidating Risk of Atherosclerosis OPERA study randomly selected middle-aged subjects with hypertension and age- and gender-matched control subjects (n = 1,045, age 51 ± 6 years, men 49.8%). After >20 years of follow-up, majority of the subjects still alive were available for reexaminations (n = 600). After excluding the subjects with mitral regurgitation, left ventricular ejection fraction <50%, and those from whom echocardiographic septal E/E' could not be reliably measured, the present analysis included 460 subjects. E/E' was divided into 3 subgroups (subgroup 1: E/E' ≤8, subgroup 2: 8 < E/E' < 15, subgroup 3: E/E' ≥15), subgroup 3 suggesting a significant diastolic dysfunction. Several baseline variables were associated with diastolic dysfunction: greater age (p = 0.001), female gender (p = 0.001), shorter height (p <0.001), larger body mass index (p = 0.008), greater systolic blood pressure (p = 0.001), greater pulse pressure (p <0.001), lower baroreflex sensitivity (p = 0.007), lower estimated glomerular filtration rate (p = 0.02), greater atrial natriuretic peptide (p = 0.001), greater fasting plasma glucose (p = 0.001), more common occurrence of diabetes (p = 0.011), and more common usage of antihypertensive medication (p = 0.001). After adjustments in the multivariate model, only systolic blood pressure (p = 0.001), shorter height (p = 0.002), and estimated glomerular filtration rate (p = 0.006) retained a significant association with the risk of developing diastolic dysfunction. In conclusion, greater systolic blood pressure, short height, and lower estimated glomerular filtration rate of the middle-aged subjects were the main determinants of development of diastolic dysfunction during a 20-year follow-up.

Gender Difference in Arterial Stiffness in a Multicenter Cross-Sectional Study: The Korean Arterial Aging Study (KAAS)

Elevated arterial stiffness has emerged as an important risk factor for future cardiovascular (CV) events in men and women. However, gender-related differences in arterial stiffness have not been clearly demonstrated. We thus determine whether gender affects arterial stiffness in subjects with and without CV risk factors. We consecutively enrolled 1,588 subjects aged 17-87 years (mean age: 46.5; 51% women) from the Korean Arterial Aging Study (KAAS), which is a multicenter registry from 13 university hospitals in Korea for the evaluation of arterial stiffness. We compared markers of arterial stiffness - central augmentation index (AIx), aortic pulse wave velocity (PWV), and pulse pressure (PP) amplification - in apparently healthy men and women without risk factors with those in high-risk subjects with a smoking habit, hypertension, diabetes, and dyslipidemia but without drug treatment. Aortic PWV and PP amplification were significantly higher in men than in women (7.78 ± 1.16 vs. 7.64 ± 1.15 m/s, p = 0.015, and 1.39 ± 0.22 vs. 1.30 ± 0.18, p < 0.001, respectively). However, women had a significantly higher central AIx than men (23.5 ± 11.9 vs. 16.1 ± 12.6%, p < 0.001). The central AIx and aortic PWV values were significantly higher in the high-risk group than in the healthy group for both men and women. In men, central AIx and aortic PWV were associated positively with age and blood pressure, and negatively with body mass index. In women, central AIx was positively related to age, diastolic blood pressure, and serum cholesterol levels. Aortic PWV was positively related to age, systolic blood pressure, fasting glucose, and heart rate. PP amplification was associated negatively with age and blood pressure and positively with heart rate in both men and women. In conclusion, arterial stiffness is mainly determined by sex, age, and blood pressure. Markers of arterial stiffness differ between men and women. Dyslipidemia and glucose contribute to a modest increase in arterial stiffness only in women. Therefore, the arteries of women may be more vulnerable to CV risk factors than those of men.

Short stature and ischemic stroke in nonvalvular atrial fibrillation: new insight into the old observation

BACKGROUND

For decades, repeated epidemiologic observations have been made regarding the inverse relationship between stature and cardiovascular disease, including stroke. However, the concept has not been fully evaluated in patients with atrial fibrillation (AF). We investigated whether patient's height is associated with ischemic stroke in patients with nonvalvular AF and attempted to ascertain a potential mechanism.

METHODS

All 558 AF patients were enrolled: 211 patients with ischemic stroke (144 men, 68 ± 10 years) and 347 no-stroke patients (275 men, 56 ± 11 years) as a control group. Clinical characteristics and echocardiographic parameters were compared between the two groups.

RESULTS

(1) Stroke patients were shorter than those in the control group (164 ± 8, vs. 169 ± 8 cm, p<0.001). However, body mass index failed to predict ischemic stroke; (2) Short stature (OR 0.93, 95% CI 0.91-0.95, p<0.001) along with left atrial (LA) anterior-posterior diameter and diastolic mitral inflow velocity (E) to diastolic mitral annuls velocity (E') (E/E') were independent predictor of stroke; (3) Height showed inverse correlation with E/E' independently, even after adjusting for other variables, including age, sex, and body weight, and comorbidities β -0.20, p=0.003); (4) LA size showed no correlation with stature (R=-0.06, p=0.18), whereas left ventricular size increases according to height of patients.

CONCLUSIONS

Short stature is associated with occurrence of ischemic stroke and diastolic dysfunction in patients with AF and preserved systolic function. Height is a non-modifiable risk factor of stroke and might be more important than obesity in Asian AF patients, who are relatively thinner than western populations.

Central hemodynamics could explain the inverse association between height and cardiovascular mortality

BACKGROUND

Mechanisms underlying the inverse relationship between height and cardiovascular mortality are unknown but could relate to central hemodynamics. We sought to determine the relation of height to central and peripheral hemodynamics, as well as clinical characteristics.

METHODS

The study population was comprised of 1,152 randomly selected community-dwelling adults (aged 67.7 ± 12.3 years; 48% men). Brachial blood pressure (BP) was recorded by sphygmomanometry; central BP and aortic pulse wave velocity were estimated by applanation tonometry. Stepwise multiple regression analysis was used to determine associations between height and central and peripheral hemodynamics.

RESULTS

Height was not significantly associated with aortic pulse wave velocity in men or women. The relationship with height and brachial systolic BP was borderline in women (β = -0.115; P = 0.051) but not significant in men (β = -0.096; P = 0.09). Conversely, central systolic BP, estimated by transfer function (β = -0.139 for men [βM]; β = -0.172 for women [βW]) or radial second systolic peak (β M = -0.239; β W = -0.281), augmentation index at 75 bpm (β M = -0.189; β W = -0.224), and aortic pulse wave timing (β M = 0.224; β W = 0.262) were independently associated with height in both sexes (P < 0.003 for all). Both men and women of greater than median height were less likely to have coronary artery disease (P < 0.05), to have systemic hypertension (P < 0.01), or to be taking vasoactive medication (P < 0.001) compared with participants of less than median height.

CONCLUSIONS

Even after correcting for conventional cardiovascular risk factors, taller individuals have more favorable central hemodynamics and reduced evidence of coronary artery disease compared with shorter individuals. These findings may help explain the decreased cardiovascular risk associated with being taller and also have important clinical consequences regarding therapy.

Women have significantly greater difference between central and peripheral arterial pressure compared with men: the Bogalusa Heart Study

Gender differences in the relationship between central and peripheral blood pressure (BP) are not well described. We sought to investigate gender differences between central systolic blood pressure (cSBP) and peripheral systolic blood pressure (pSBP) in adults in the Bogalusa study population. This study enrolled adults in a cross sectional survey conducted in 2007 to 2010. BP was measured with a standard cuff and Omron applanation tonometer. Data were available from 876 participants. Participants were 57.9% female and 42.1% male (mean age, 43.5 ± 4.4 years). Mean (standard deviation) for cSBP - pSBP was 1.0 (6.9) for males and 7.4 (5.2) for females (P < .001). Augmentation index (AI) was higher in women (men, 70.8 ± 14 vs. women: 85.5 ± 13; P < .01), as well as AI standardized to heart rate (HR) of 75 (AI@75; men, 68.5 ± 13 vs. women, 84.4 ± 11.8; P < .01). Female participants had greater difference between cSBP and pSBP than males. This suggests that, given similar peripheral BP, females might be at higher risk for developing target organ damage. Women in this study had higher AI, which may contribute to the difference found between cSBP and pSBP. These findings may explain why women have more age-related left ventricular hypertrophy, and poorer prognosis following myocardial infarction compared with males.

Association of left ventricular motion and central augmentation index in healthy young men

BACKGROUND

Central blood pressure is a determinant of cardiovascular outcome; however, it can be described by parameters other than systolic and diastolic pressure with central augmentation index (AIx) often utilized. Although generally considered as determined by peripheral pressure wave reflection, not all data are consistent with this interpretation of AIx. We hypothesized that the motion of the heart during systole may influence central pressure waveform morphology, including the AIx.

METHOD

We studied the carotid pressure waveform, aortic stiffness and endothelial function in 20 healthy young men (full data available in 19). Arterial stiffness was measured by carotid femoral pulse wave velocity (cfPWV), endothelial function by peripheral arterial plethysmography (PAPl) and central blood pressure waveform by carotid applanation tonometry. Basal cardiac motion was assessed with pulsed wave tissue Doppler imaging of the septal mitral annulus.

RESULTS

Carotid AIx decreased after the administration of glyceryl trinitrate by 11.3 ± (sem) 4.6% (P = 0.02); however, time to the inflection point (Ti) did not change. During systolic contraction at both baseline and after glyceryl trinitrate, time to peak annular systolic velocity was directly related to, and always preceded, carotid Ti (R(2) = 0.81; P < 0.01). Carotid Ti and AIx were not related to cfPWV or endothelial function.

CONCLUSION

In fit young men, rather than only being a consequence of arterial properties Ti, and therefore central AIx, may be substantially determined by left ventricular systolic function. These findings question the interpretation of central AIx as a measure of pressure wave reflection and aortic stiffness and potentially impact its interpretation in diagnosis and treatment of cardiovascular risk.

RADIAL DIASTOLIC AUGMENTATION INDEX IS A USEFUL PREDICTOR OF ARTERIAL STIFFNESS

Diastolic augmentation index (DAI), calculated from radial artery pressure waveform, has been associated with the risk of cardiovascular disease. In the present study, we aimed to evaluate whether DAI could be used as a predictor of arterial stiffness and the effect of heart rate (HR) on it. Measurements of anthropometric parameters, blood pressure (BP), Augmentation index (AI) and DAI were taken in 242 healthy subjects (130 men and 112 women; age 16–78 years). DAI and AI were measured in a subgroup of 16 subjects (10 men and 6 women; age 19–69 years) in a two-month follow-up study, which aimed to investigate the effect of HR changes. Statistically, DAI was higher in women compared to men (44.8% ± 7.7% compared with 43.6% ± 6.9%, P < 0.05). DAI was decreased with age (men: r = -0.755, P < 0.05; women: r = -0.708, P < 0.05) and negatively correlated to AI (men: r = -0.704, P < 0.05; women: r = -0.756, P < 0.05). There was no significant change in DAI when HR ranged from 60 to 80 bpm. Multiple regression analysis demonstrated fewer determinants affect DAI compared with AI. These findings indicate that the simple radial DAI might be used as an index to assess vascular aging.

Gender differences in artery wall biomechanical properties throughout life

Elevated large artery stiffness and pulse pressure have emerged as important risk factors for cardiovascular disease. The genders differ in large artery biomechanical properties throughout the lifespan with females displaying higher stiffness than males during the prepubertal years and a dramatic increase after menopause. Males on the other hand experience an increase in arterial stiffness postpuberty and a linear increase thereafter, suggesting that females have intrinsically stiffer large arteries than males, but that such effects are mitigated by sex steroids during the reproductive years. This review discusses anthropometric and sex steroid influences on gender differences in large artery stiffness and pressure dynamics from childhood to senescence. In particular, the sex-specific effects of estrogen, progesterone and testosterone on vascular structure and function and how these influence arterial stiffness are explored. These factors may contribute in part to the observed gender differences in the pathophysiology and clinical manifestations of cardiovascular disease.

Arterial stiffness, central blood pressure and body size in health and disease

BACKGROUND

Body size is associated with increased brachial systolic blood pressure (SBP) and aortic stiffness. The aims of this study were to determine the relationships between central SBP and body size (determined by body mass index (BMI), waist circumference and waist/hip ratio) in health and disease. We also sought to determine if aortic stiffness was correlated with body size, independent of BP.

METHODS

BMI, brachial BP and estimated central SBP (by SphygmoCor and radial P2) were recorded in controls (n=228), patients with diabetes (n=211), coronary artery disease (n=184) and end-stage kidney disease (n=68). Additional measures of waist circumference and arterial stiffness (aortic and brachial pulse wave velocity (PWV)) were recorded in a subgroup of 75 controls (aged 51 ± 12 years) who were carefully screened for factors affecting vascular function.

RESULTS

BMI was associated with brachial (r=0.30; P<0.001) and central SBP (r=0.29; P<0.001) in the 228 controls, but not the patient populations (r<0.13; P>0.15 for all comparisons). In the control subgroup, waist circumference was also significantly correlated with brachial SBP (r=0.29; P=0.01), but not central SBP (r=0.22; P=0.07). Independent predictors of aortic PWV in the control subgroup were brachial SBP (β=0.43; P<0.001), age (β=0.37; P<0.001), waist circumference (β=0.39; P=0.02) and female sex (β=-0.24; P=0.03), but not BMI.

CONCLUSION

In health, there are parallel increases in central and brachial SBP as BMI increases, but these relationships are not observed in the presence of chronic disease. Moreover, BP is a stronger correlate of arterial stiffness than body size.

Reduced arterial compliance associated with metabolic syndrome in Chinese children and adolescents

OBJECTIVE

To explore the metabolic syndrome and its association with arterial compliance in Chinese children and adolescents.

METHODS

337 participants aged 6 to 18 years with males accounted for 55.8% were grouped according to their traits of metablic syndrome. Anthropometry, blood pressure, fasting plasma glucose, insulin and serum lipid profile were measured. Homeostasis model was assessed and insulin resistance (HOMA-IR) index was measured and calculated for estimating individual insulin resistance. Arterial compliance was also measured using digital pulse wave analyzing method (Micro medical, London), and stiffness index was calculated.

RESULTS

The stiffness index in participants with metablic syndrome was significant higher than that in participants with no riskof metablic syndrome [(7.69 +/- 1.63) vs (6.25 +/- 0.86) m/s, P < 0.01] and stiffness index and HOMA-IR were progressively increased with the increase of traits of metablic syndrom (P for linear trend < 0.001). After gender, age, and pubertal development were adjusted, both traits of metablic syndrome and HOMA-IR were correlated positively with stiffness index (both P < 0.05).

CONCLUSION

The clustering of metablic syndrome was closely associated with risk at increased arterial stiffness in Chinese children and adolescents. It was suggested that arterial compliance assessment of children and adolescents might be an important measure for prevention of cardiovascular diseases.

Pulse wave velocity is more closely associated with cardiovascular risk than augmentation index in the relatively low-risk population

Pulse wave velocity (PWV) and augmentation index (AI) are both indirect indicators of arterial stiffness, which is an independent predictor of morbidity and mortality in cardiovascular diseases. The aim of this study was to assess the association between carotid AI (CAI), carotid-femoral PWV (CFPWV), and Framingham risk score (FRS), and to evaluate the factors determining CAI and CFPWV. Carotid AI and CFPWV were measured by applanation tonometry in 177 consecutive subjects without evidence of significant cardiovascular disease. Correlations between CAI and FRS and CFPWV and FRS were analyzed and major determinants of CAI and CFPWV were assessed. The mean age was 60.5 +/- 11.9 years and 112 (63%) of study patients were men. There was a significant association between CFPWV and FRS (r = 0.417, P < 0.001) and a weaker but also significant relation between CAI and FRS (r = 0.267, P < 0.001). CFPWV was significantly related to FRS in both men and women (P < 0.001 in both sexes), whereas the relation between CAI and FRS was significant only in women (P < 0.001). Our results suggest that CFPWV may be associated with CVD risk irrespective of sex, whereas CAI may be associated with CVD risk in women only.

Dissociation of aortic pulse wave velocity with risk factors for cardiovascular disease other than hypertension: a systematic review

Carotid-femoral pulse wave velocity (cfPWV), a measure of large artery stiffness, is an important predictor of cardiovascular events. This has been attributed to it being an integrative measure of the impact of cardiovascular risk factors on the arterial wall. Pulse wave velocity is strongly associated with age and blood pressure. However, findings with regard to its relation with other risk factors have been inconsistent. We performed a systematic review of cross-sectional published literature reporting independent associations of cfPWV in multivariable regression models. Articles were selected from a PubMed search using a prespecified search strategy. Studies were included if they did the following: (1) measured cfPWV; (2) reported on associations with cfPWV from regression models; and (3) considered age and blood pressure in the model. From 637 retrieved articles, 65 met our inclusion criteria, and 12 studies were included from reference searches. Age and blood pressure were consistently independently associated with cfPWV (91% and 90% of studies, respectively). Diabetes mellitus was associated with cfPWV in 52% studies, but the strength of the association was low. The majority of studies found no independent association between cfPWV and sex, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, smoking, or body mass index. The contribution of risk factors other than age and blood pressure to cfPWV is, thus, small or insignificant. The prognostic value of cfPWV may relate to a process of arterial ageing unrelated to classic risk factors other than hypertension.

Drug effects on the mechanical properties of large arteries in humans

1. Arteries become stiffer with increasing age and various disease states. A complete description of arterial mechanical properties in vivo is not possible, although a number of methods have been used. 2. Detailed discussion in the present review is limited to pulse wave velocity and estimates of central waveform morphology derived by the application of a generalized arterial transfer function. 3. Many drugs affect these parameters, either increasing or decreasing apparent stiffness. However, the extent to which changes reflect changes in blood pressure rather than more fundamental vessel wall properties remains unclear. Similarly, it is as yet unknown whether determining the need for, or assessing the effectiveness of, drug treatment by the assessment of arterial mechanical properties will offer any advantage and the usefulness of these techniques as routine clinical tools remains to be established.

Arterial Ultrasonography and Tonometry as Adjuncts to Cardiovascular Risk Stratification

Myocardial infarction and stroke often occur without prior warning in asymptomatic individuals. Identifying individuals at risk is important for cost-effective use of preventive therapies. Algorithms based on risk factors statistically associated with cardiovascular events classify individuals into high-risk, intermediate-risk, or low-risk categories. However, more than one-third of adults in the U.S. are in the intermediate-risk category, and decisions regarding therapy are challenging in this subset. Testing for alterations in arterial function and structure that predate cardiovascular events may help refine cardiovascular risk assessment in the intermediate-risk group and identify candidates for aggressive therapy. Vascular ultrasonography and tonometry are promising test modalities for assessment of arterial function and structure in asymptomatic subjects. Several prospective studies have shown that measures of arterial function and structure provide prognostic information incremental to conventional risk factors. Standardization of methodology and establishment of quality control standards in the performance of these tests could facilitate their integration into clinical practice as adjuncts to existing cardiovascular risk stratification algorithms.

Noninvasive assessment of preclinical atherosclerosis

Initially considered as a semipermeable barrier separating lumen from vessel wall, the endothelium is now recognised as a complex endocrine organ responsible for a variety of physiological processes vital for vascular homeostasis. These include the regulation of vascular tone, luminal diameter, and blood flow; hemostasis and thrombolysis; platelet and leucocyte vessel-wall interactions; the regulation of vascular permeability; and tissue growth and remodelling. The endothelium modulates arterial stiffness, which precedes overt atherosclerosis and is an independent predictor of cardiovascular events. Unsurprisingly, dysfunction of the endothelium may be considered as an early and potentially reversible step in the process of atherogenesis and numerous methods have been developed to assess endothelial status and large artery stiffness. Methodology includes flow-mediated dilatation of the brachial artery, assessment of coronary flow reserve, carotid intimamedia thickness, pulse wave analysis, pulse wave velocity, and plethysmography. This review outlines the various modalities, indications, and limitations of available methods to assess arterial dysfunction and vascular risk.

Increased arterial stiffness in remote Indigenous Australians with high risk of cardiovascular disease

OBJECTIVE

To assess central and peripheral arterial stiffness in Indigenous and European Australians with and without type 2 diabetes using applanation tonometry to obtain the augmentation index (AI) and pulse wave velocity (PWV).

METHODS

AI was assessed in 162 Indigenous Australians (60 with type 2 diabetes) participating in a population-based study and 121 Australians of European ancestry (38 with diabetes) of similar age and sex. PWV was assessed in a subgroup: n = 62 indigenous, n = 118 European participants.

RESULTS

The indigenous group had higher AI than the European group [mean (SD) 32 (12) versus 24 (12)%, P < 0.0001] and carotid-femoral PWV [8.4 (1.8) versus 7.1 (2.2) ms(-1), P < 0.0001]. There were no significant differences between groups regarding blood pressure and total cholesterol; however, indigenous individuals had higher fasting glucose, insulin, haemoglobin A1c, triglycerides, waist circumference (despite lower body mass index), and a higher prevalence of cigarette smoking. Fifty-five per cent of the variance in AI was explained on multiple regression analysis by age, sex, indigenous participant, heart rate, mean arterial pressure, height, triglycerides and waist circumference. Age, indigenous participant, heart rate, mean arterial pressure and antihypertensive medication explained 56% of the variance in PWV. Variables of the metabolic syndrome and smoking, C-reactive protein (CRP), homocysteine and heart rate clustered with indigenous status on factor analysis.

CONCLUSIONS

Indigenous Australians have higher indices of peripheral and central arterial stiffness than European Australians of similar age and sex. Factor analysis revealed that metabolic syndrome variables, smoking, CRP, homocysteine and heart rate clustered with 'indigenous participant' and may explain increased arterial stiffness in this group.

Association of metabolic syndrome with arterial compliance in children and adolescents

The association of metabolic syndrome (MS) with arterial compliance in children and adolescents was explored. 337 subjects (188 men and 149 women) aged 6-18 (10.95 ± 3.01) years, out of "Beijing Child Metabolic Syndrome Study", were divided into three case groups (one component, two components, three & more components of MS) and one control group based on the Cook's MS definition in children and adolescents. Measurements including anthropometry, blood pressure, fasting plasma glucose and insulin, serum lipid profile were done. Homeostasis model assessment for insulin resistance (HOMA-IR) index was calculated for estimating individual insulin resistance. Arterial compliance was measured using digital pulse wave analyzing method from the pulse trace machine (Micro medical, London), and then the stiffness index (SI) was determined. The mean value of SI in MS group was significant higher than that in control group [(7.69 ± 1.63) vs (6.25 ± 0.86) m/s, P<0.01]. With the increase of the clustering of MS components, SI and HOMA-IR were gradually increased. After taking account of gender, age and pubertal development, the partial correlation analysis showed that the amount of components of MS and HOMA-IR were positively correlated with SI (both P values were less than 0.05). The arterial compliance of MS group was significantly lowered in children and adolescents, and with the increase of the clustering of MS components, arterial compliance was gradually decreased. It was suggested that arterial compliance assessment in children and adolescents was important for early prevention of cardiovascular diseases.

Selective angiotensin receptor antagonism with valsartan decreases arterial stiffness independently of blood pressure lowering in hypertensive patients

Angiotensin II plays a key role in the development of vascular disease. We examined the long-term effects of selective angiotensin II receptor (ATR) blockade with valsartan on arterial wall stiffness. Brachial to ankle pulse wave velocity (baPWV) was measured in 28 women and 25 men with hypertension (mean age: 62+/-2 years). The measurements were repeated after 24 weeks of treatment with valsartan, 40 to 160 mg/day, with (n=10) or without (n=36) concomitant statin therapy. By multiple regression analysis, baseline baPWV was correlated with age (p<0.001), systolic blood pressure (SBP, p<0.0001), body mass index (p=0.018), and pulse pressure (p=0.005), but not with total cholesterol (p=0.446). Valsartan lowered mean SBP and diastolic blood pressure (DBP) from 155+/-3 to 140+/-3 mmHg and from 90+/-2 to 82+/-2 mmHg, respectively, and mean baPWV from 1,853+/-49 to 1,682+/-52 cm/s. Lowering of baPWV was not influenced by statin therapy. An overlap analysis was performed to separate the effect of angiotensin II receptor blockade from that of blood pressure (BP) lowering. The decrease in the baPWV value of 1,794+/-46 cm/s before valsartan (n=39) vs. 1,663+/-45 cm/s during valsartan (p=0.048, n=31) at a similar mean SBP level (149+/-2 vs. 146+/-3 mmHg, p=0.304) confirmed that ATR blockade had a beneficial effect independent of BP lowering. SBP strongly influences baPWV. However, the decrease in baPWV with valsartan was independent of BP lowering. Statins had no synergistic effect on baPWV. Lowering of baPWV may account for the therapeutic benefit conferred by valsartan independent of its BP-lowering effect.

Noninvasive Arterial Measurements of Vascular Damage in Healthy Young Adults: Relation to Coronary Heart Disease Risk

PURPOSE

There is an increasing interest in noninvasive measurements of early structural or functional changes in large arteries such as pulse wave velocity (PWV), carotid intima-media thickness (CIMT), and augmentation index (AIx). These measurements may be applied in etiologic or prognostic research. The role of the AIx as a marker of cardiovascular risk has not fully been established. Our aim was to study whether AIx is related to coronary heart disease (CHD) risk and to compare the strength of the relations of AIx, PWV, and CIMT with cardiovascular risk in healthy young adults.

METHODS

Our study included 224 men and 273 women (mean age 28 years, range 27-30 years) from the Atherosclerosis Risk in Young Adults (ARYA) study. Cardiovascular risk profile was determined and CHD risk was estimated using the Framingham risk score. AIx, PWV and CIMT were measured using standard methods. Data were analyzed in strata of gender using linear regression models.

RESULTS

In men, PWV and CIMT were most strongly related to CHD risk. The increase in CHD risk per standard deviation increase in measurement was 0.24%/m/s, 95% CI (0.01;0.33) and 0.32%/mm, 95% CI (0.08;0.55), whereas the AIx was not significantly related to CHD risk (0.09 %/% 95% CI [-0.15;0.33]). In women, AIx, PWV, and CIMT were weakly but significantly related to CHD risk; there was no clear difference between the measurements.

CONCLUSION

In young men, PWV and CIMT are better measures of CHD risk than AIx. In women, AIx, PWV and CIMT estimate CHD risk equally well.

Central obesity is associated with reduced peripheral wave reflection in Indigenous Australians irrespective of diabetes status

OBJECTIVE

To determine the influence of central obesity and type 2 diabetes on peripheral wave reflection in Indigenous Australians.

DESIGN AND METHODS

A cross-sectional study of remote Indigenous Australians with (n = 43) and without (n = 54) type 2 diabetes of similar age (47 years) and sex; using anthropometric and bioelectrical impedance measures of obesity and applanation tonometry to determine the aortic augmentation index (AI) as an index of peripheral wave reflection.

RESULTS

Indices of obesity were significantly higher in the diabetic than non-diabetic participants [body mass index (BMI): 27.3 versus 24.6 kg/m, P = 0.018; waist circumference: women 101 versus 94 cm, P = 0.008, men 102 versus 91 cm, P = 0.039]. AI was negatively related to obesity: BMI (r = -0.35, P = 0.0003), weight (r = -0.44, P < 0.0005), waist circumference (r = -0.34, P = 0.0003) and fat mass (r = -0.35, P < 0.0005). There was no significant difference in AI between the groups with and without diabetes. On multiple regression analysis, 66% of the variance in AI was explained with the following significant predictors: age, heart rate, male gender, fat mass and mean arterial pressure. Similar results were obtained when weight, waist circumference or BMI were substituted for fat mass.

CONCLUSION

When compared with Indigenous Australians without diabetes, those with type 2 diabetes do not have greater aortic pressure augmentation from peripheral wave reflection. However, obesity, irrespective of the index used, was related to lower peripheral wave reflection in both those with and without type 2 diabetes.

Age-related factors that confound peripheral pulse timing characteristics in Caucasian children

Characteristics obtained from peripheral pulses can be used to assess the status of cardiovascular system of subjects. However, nonintrusive techniques are preferred when prolonged monitoring is required for their comfort. Pulse transit time (PTT) measurement has showed its potentials to monitor timing changes in peripheral pulse in cardiovascular and respiratory studies. In children, the common peripheries used for these studies are fingers or toes. Presently, there is no known study conducted on children to investigate the possible physiologic parameters that can confound PTT measure at these sites. In this study, PTT values from both peripheral sites were recorded from 55 healthy Caucasian children (39 male) with mean age of 8.4+/-2.3 years (range 5-12 years). Peripheries' path length, heart rate, systolic blood pressure, diastolic blood pressure (DBP) and mean arterial pressure (MAP) were measured to investigate their contributions to PTT measurement. The results reveal that PTT is significantly related to all parameters (P<0.05), except for DBP and MAP. Age is observed to be the dominant factor that affects PTT at both peripheries in a child. Regression equations for PTT were derived for measuring from a finger and toe, (6.09 age+189.2) ms and (6.70 age+243.0) ms, respectively.

Predictive regression equations and clinical uses of peripheral pulse timing characteristics in children

Studies have shown that increased arterial stiffening can be an indication of cardiovascular diseases like hypertension. In clinical practice, this can be detected by measuring the blood pressure (BP) using a sphygmomanometer but it cannot be used for prolonged monitoring. It has been established that pulse wave velocity (PWV) is a direct measure of arterial stiffening but its usefulness is hampered by the absence of non-invasive techniques to estimate it. Pulse transit time (PTT) is a simple and non-invasive method derived from PWV. However, limited knowledge of PTT in children is found in the present literature. The aims of this study are to identify independent variables that confound PTT measure and describe PTT regression equations for healthy children. Therefore, PTT reference values are formulated for future pathological studies. Fifty-five Caucasian children (39 male) aged 8.4 +/- 2.3 yr (range 5-12 yr) were recruited. Predictive equations for PTT were obtained by multiple regressions with age, vascular path length, BP indexes and heart rate. These derived equations were compared in their PWV equivalent against two previously reported equations and significant agreement was obtained (p < 0.05). Findings herein also suggested that PTT can be useful as a continuous surrogate BP monitor in children.

Augmentation index, pulse pressure amplification and superoxide anion production in patients with coronary artery disease

BACKGROUND

Free oxygen radicals appear to be involved in several processes that contribute to atherogenesis and increased arterial stiffness.

METHODS

The aim of our study was to evaluate arterial stiffness and the production of superoxide anions by activated polymorphonuclear neutrophils (PMN) obtained from patients with stable coronary artery disease (CAD). Thirty four consecutive patients were studied (21 men, 13 women, mean age 58 years) who underwent coronary angiography. Arterial stiffness was assessed by pulse wave analysis using a validated system (Sphygmocor Mx, AtCor Medical). Superoxide anion production by activated neutrophils was determined by a spectrophotometric method involving the measurement of cytochrome C reduction. The extent of coronary narrowing was estimated by calculation of the Gensini score.

RESULTS

Superoxide anion production by stimulated PMN showed a significant positive correlation with the augmentation index (AIx) and a significant negative correlation with pulse pressure amplification (PPA), (r=0.4, p=0.02; r=-0.5 and p=0.0026 respectively). In multivariable analyses, after adjustment for age, gender and Gensini score, superoxide anions and BMI were significant predictors of AIx (R2=57.37%, p=0.001) and PPA (R2=49.04%, p=0.008). Superoxide anion production was significantly higher in the middle (52.0+/-5.8 nmol O2-/2.5x10(6) PMN/30 min) and upper teriles (62.7+/-5.6) of AIx in comparison with the first tertile 31.8+/-4.1 (p< or =0.05, p< or =0.001). Moreover, superoxide anion production in the highest tertile of PPA was significantly lower (35.6+/-4.3 nmol O2-/2.5x10(6) PMN/30 min) than that in the tertile (60.8+/-6.2, p< or =0.05). Neither the augmentation index nor pulse pressure amplification correlate with the severity of coronary atherosclerosis as indicated by the Gensini score.

CONCLUSIONS

markers of arterial stiffness, AIx and pulse pressure amplification correlate with superoxide anion production but not with the severity of atherosclerosis in coronary arteries.

Evaluation of Carotid-Femoral Pulse Wave Velocity

Carotid-femoral pulse wave velocity (PWV), a measure of arterial stiffness, is determined from the time taken for the arterial pulse to propagate from the carotid to the femoral artery. Propagation time is measured variously from the foot of the waveform or point of maximum upslope. We investigated whether these methods give comparable values of PWV at rest, during β-adrenergic stimulation, and pacing-induced tachycardia. In subjects at rest (n=43), values obtained using the foot-to-foot method (SphygmoCor system) were 1.7±0.75 m/s (mean±SD) greater than those obtained using the maximum slope (Complior system) at a mean value of 12 m/s. Isoprotenerol (0.5 to 1.5 μg/min; n=10), and pacing (in subjects with permanent pacemakers; n=11) increased heart rate but had differential effects on systolic blood pressure and pulse pressure. The increase in heart rate produced by isoprotenerol (18±3 bpm) and pacing (40 bpm) was associated with an increase in PWV measured using both systems (increases of 0.7±0.2 m/s and 0.9±0.2 m/s for SphygmoCor and Complior, respectively, during isoprotenerol and increases of 2.1±0.5 m/s and 1.1±0.2 m/s for SphygmoCor and Complior, respectively, during pacing, each P <0.001). Reanalysis of waveforms recorded from the Complior system using the foot-to-foot method produced similar values of PWV to those obtained with the SphygmoCor, confirming that the difference between these systems was attributable to the timing algorithm rather than other aspects of signal acquisition. Carotid-femoral PWV is critically dependent on the method used to determine propagation time, but this does not account for variation of PWV with heart rate.

Arterial stiffness and the systolic hypertension syndrome

PURPOSE OF REVIEW

This review is intended to provide the background for a new comprehensive hemodynamic view of the syndrome of systolic or wide pulse pressure hypertension and its hallmark abnormality: increased central arterial stiffness.

RECENT FINDINGS

Studies of the pathogenesis of systolic hypertension have lagged. This review describes the systolic hypertension syndrome as a complex set of hemodynamic maladaptations that include stiff central arteries, normal peripheral arteries with variable pressure amplification characteristics, arteriolar constriction, microcirculatory rarefaction, metabolic abnormalities, cardiac hypertrophy, and increased blood pressure variability. Because the structural and functional properties of arteries of different caliber are highly heterogeneous and vary with aging and disease, simple measurements such as standard brachial artery blood pressure, brachial pulse pressure, or mean arterial pressure are inadequate to provide meaningful insight into the pathophysiology of the syndrome. Additional parameters developed to describe changes in arterial mechanics (arterial compliance or stiffness, elastic modulus, impedance, pulse wave velocity, augmentation index, and pulse pressure amplification) are intrinsically limited and are directly or indirectly pressure-dependent. Quantitation of central arterial stiffness provides a modest increment in cardiovascular and renal risk stratification.

SUMMARY

Better clinical management of systolic hypertension depends on greater insight into the syndrome as a whole, more critical analysis of existing techniques, and the development of new approaches.

Confounding effects of heart rate on pulse wave velocity in paced patients with a low degree of atherosclerosis

BACKGROUND

Pulse wave velocity (PWV), an index of arterial wall stiffness, is modulated by blood pressure (BP). Whether heart rate (HR) is also a modulator of PWV is controversial. Recent research involving mainly patients with high aortic PWV have found either no change or a positive correlation between the two. Given that PWV is increasingly being measured in cardiovascular studies, the relationship between HR and PWV should be known in patients with preserved arterial wall elasticity.

OBJECTIVE

The aim of this study was to evaluate the importance of HR as a determinant of the variability in PWV in patients with a low degree of atherosclerosis.

DESIGN AND METHODS

Fourteen patients (five female, nine male; aged 68 +/- 8 years) were evaluated post pacemaker implantation due to sick sinus or carotid hypersensitivity syndromes. Carotid-femoral PWV was measured at rest and during atrial pacing at 80, 90 and 100 bpm (paced HR). Arterial femoral blood flow (AFBF) was measured by echodoppler.

RESULTS

PWV increased from 6.2 +/- 1.5 m/s (mean +/- SD) during resting sinus rhythm (HR 62 +/- 8 bpm; mean +/- SD) to 6.8 +/- 1.0, 7.0 +/- 0.9, and 7.6 +/- 1.1 m/s at pacing rates of 80, 90 and 100 bpm, respectively (P < 0.0001). Systolic (SBP) and mean blood pressure (MBP) remained constant at all HR levels, whereas AFBF increased in a linear fashion.

CONCLUSIONS

These results demonstrate that even in patients with a low degree of atherosclerosis, HR is a potential modulator of carotid-femoral PWV.

The T-allele of the C825T polymorphism is associated with higher arterial stiffness in young healthy males

Arterial stiffening is the major cause of increasing systolic blood pressure in arterial hypertension. Increased arterial stiffness is one major mechanism responsible for morbidity and mortality in hypertension. A C825T polymorphism was identified in the gene encoding the G-protein beta3 subunit (GNB3), and an association of the T-allele with hypertension was demonstrated in several studies. In order to identify a pathogenetic link between hypertension and arterial stiffness, we compared two indices of arterial stiffness, pulse wave velocity (PWV) and augmentation index, in young, healthy men with and without the 825T-allele under resting conditions. PWV was determined from pressure tracing over carotid and femoral arteries in 99 subjects (CC: n=43; CT&TT: n=56). Augmentation index was derived in 72 subjects (CC: n=30; CT&TT: n=42) by pulse wave analysis using radial applanation tonometry. Carriers of the 825T-allele exhibited a significantly higher PWV compared to subjects with the CC genotype (6.0+/-0.1 m/s (TC&TT) vs 5.7+/-0.1 m/s (CC); P=0.0251). There was also a significant difference (P = 0.0448) in augmentation index between carriers of the T-allele (CT&TT: 3.4+/-2.9%) and controls with the CC -genotype (-5.0+/-4.1 %). There was no difference in any other anthropometric (age, height, weight, body mass index) or haemodynamic (heart rate, peripheral and central blood pressure). In summary, the C825T polymorphism is associated with higher arterial stiffness in young, healthy males. Arterial stiffening may pathogenetically contribute to the development of hypertension in carriers of the T-allele.

Diastolic blood pressure is an important determinant of augmentation index and pulse wave velocity in young, healthy males

Pulse wave velocity (PWV) and augmentation index are widely used measures of arterial stiffness. The purpose of this study was to evaluate the role of blood pressure as a determinant of both indices independent of potentially confounding factors including gender, age and cardiovascular disorders. A total of 77 young, healthy subjects were investigated under resting conditions. Augmentation index was derived by pulse wave analysis using carotid applanation tonometry. PWV was determined from pressure tracing over the carotid and femoral artery. The relations between stiffness markers and haemodynamic parameters were analysed by simple (r) and multiple (beta) regression analysis. Using simple regression analysis, augmentation index was correlated to age (r=0.292, P=0.0105), diastolic blood pressure (DBP, r=0.483, P<0.0001), mean arterial blood pressure (MAP, r=0.381, P=0.0007), pulse pressure (r=-0.414, P=0.0002) and total peripheral resistance (r=0.266, P=0.0204). After multiple regression analysis, augmentation index remained significantly correlated only to DBP (beta=0.347, P=0.0051). Using simple regression analysis, PWV was correlated to age (r=0.304, P=0.0067), systolic blood pressure (r=0.280, P=0.0129). DBP (r=0.455, P<0.0001), MAP (r=0.446, P&<0.0001) and heart rate (r=0.348, P=0.0018). After multiple regression analysis, PWV remained correlated only to age (beta=0.218, P=0.0422) and DBP (beta=0.4105, P=0.0316). In summary, DBP is an important determinant of augmentation index and PWV in young, healthy males. Further studies are needed to characterize the impact of blood pressure on arterial stiffness in other populations including females and older subjects.

Augmentation index is associated with cardiovascular risk

OBJECTIVES

Augmentation index is a parameter measured by pulse wave analysis (PWA) and is used as a surrogate measure of arterial stiffness. The aim of this study was to assess whether augmentation index is associated with cardiovascular risk, as well as to evaluate whether the determinants of augmentation index are different in patients with cardiovascular disease compared to healthy subjects.

DESIGN AND METHODS

We related augmentation index to risk scores in 216 subjects with or without a cardiovascular disease. Subjects without cardiovascular disease were classified according to the 'coronary risk chart' of the European Society of Cardiology (ESC), and those with cardiovascular disease were classified using the SMART (Second Manifestations of ARTerial disease) score and the EPOZ (Epidemiological Prevention study Of Zoetermeer) function. Augmentation index was derived by PWA using carotid applanation tonometry. Augmentation index was also correlated to age, blood pressure, heart rate, smoking history, cholesterol, height, body mass index and gender in subjects categorized as healthy or with cardiovascular disease.

RESULTS

Augmentation index significantly increased with increasing risk scores (P < 0.0001) and was significantly correlated to cardiovascular risk (ESC: P < 0.0001; SMART: P < 0.0001; EPOZ: P < 0.0001). In subjects with and without cardiovascular disease, augmentation index was correlated with diastolic blood pressure, heart rate, height and gender. Age was found to be significantly correlated with augmentation index only in healthy subjects but not in those with atherosclerotic disease.

CONCLUSIONS

Our findings suggest that augmentation index may be a useful marker of cardiovascular risk. Further studies are required to investigate the relationship between age and augmentation index in subjects with atherosclerotic disease.