Combined continuous ethinyl estradiol/norethindrone acetate does not improve forearm blood flow in postmenopausal women at risk for cardiovascular events: a pilot study.

OBJECTIVE: This study sought to determine whether combined continuous ethinyl estradiol and norethindrone acetate, a postmenopausal hormone therapy (HT) combination designed to have fewer side effects than cyclical therapies and therapies using medroxyprogesterone acetate (MPA), could improve vascular endothelial function in postmenopausal women with risk factors for cardiovascular disease (CVD). METHODS: Eighteen postmenopausal women (mean age 62 +/- 11 years) participated in a randomized, placebo-controlled, crossover design trial of 10 microg estradiol/1 mg norethindrone acetate given once daily for 3 months, with a 1-month washout period between placebo and active treatment phases. Vascular reactivity was assessed at each phase of the study using high-frequency brachial artery ultrasound in response to flow-mediated hyperemia, cold pressor testing, and sublingual nitroglycerin. Markers of cardiovascular risk, including cholesterol levels, inflammatory markers, fibrinolytic markers, and solubilized adhesion molecules, were also measured at each phase. RESULTS: We found no significant difference in vascular reactivity measurements during active treatment with ethinyl estradiol/norethindrone acetate vs. placebo. C-reactive protein (CRP) levels increased significantly during active treatment, and high-density lipoprotein (HDL) levels decreased significantly. Vascular cell adhesion molecule-1 (VCAM-1) levels declined during active treatment. Plasminogen activator inhibitor-1 (PAI-1) levels were inversely correlated with flow-mediated hyperemic vascular reactivity, independent of active treatment or placebo phases. CONCLUSIONS: In this older postmenopausal population with at least one cardiovascular risk factor, treatment with combined continuous ethinyl estradiol and norethindrone acetate failed to improve vascular endothelial function. The agent's proinflammatory effect or subclinical atherosclerosis in this population may have contributed to this finding.

Valsartan Improves Insulin Sensitivity without Altering Vascular Function in Healthy Overweight Adults without the Metabolic Syndrome.

Background. We investigated hyperactivity of the renin-angiotensin system (RAS) as a cause of endothelial dysfunction in obese humans. Methods. Thirty five healthy overweight (BMI = 33.6 +/- 6.6 kg m (2)) adults (33 +/- 10 years old) without cardiovascular risk factors received valsartan (160 mg) orally daily or a matching placebo for 6 weeks each. Results. Baseline flow-mediated dilatation (FMD) and nitroglycerin-mediated dilatation (NMD) were not altered by placebo or valsartan. However, fasting plasma insulin was significantly decreased by valsartan compared to placebo (-4.6 +/- 16.0 muUmL(1) versus -0.4 +/- 11.6 muUmL(1), P = 0.032) with no changes in glucose. A secondary analysis in patients with elevated waist to hip ratios (ÿ0.85, n = 18) showed an increase in FMD with valsartan. Conclusions. Our findings suggest that angiotensin 2 receptor blockade may aid in the prevention of diabetes even at the earliest stages of risk due solely to uncomplicated obesity. The lack of an improvement in FMD does not support a central role of RAS-hyperactivity in the etiology of the vascular dysfunction due solely to obesity. However, it is possible that obese patients with central adiposity may improve FMD with RAS blockade, and future investigation is warranted in this subgroup.

Angiotensin receptor blockade improves vascular compliance in healthy normotensive elderly individuals: results from a randomized double-blind placebo-controlled trial.

The renin-angiotensin system (RAS) may play a role in vascular aging. The authors hypothesized that blockade of the angiotensin II type 1 receptor with an angiotensin receptor blocker in healthy elderly subjects improves vascular compliance and endothelial function. Thirty-five healthy elderly subjects were randomized to valsartan or placebo in a double-blind crossover study after baseline testing for pulse wave velocity, aortic augmentation index, and brachial artery flow-mediated dilation. Angiotensin II type 1 receptor blockade with valsartan improved vascular compliance but not flow-mediated dilation. Changes in pulse wave velocity with valsartan were correlated with change in central systolic blood pressure and pulse pressure and remained associated on multivariate analysis. Change in pulse wave velocity after adjusting for degree of blood pressure change, age, and sex remained correlated with assignment to the angiotensin receptor blocker but not placebo. These data suggest that angiotensin II type 1 receptor blockade improves aging-related vascular compliance without alterations in flow-mediated dilation. Mechanisms regulating compliance and endothelial function are complex and may not necessarily converge in aging.

Intrasubject variability of radial artery flow-mediated dilatation in healthy subjects and implications for use in prospective clinical trials.

Flow-mediated dilation (FMD) in the brachial artery is a widely used end point in clinical trials despite large within-subject variability and a small dynamic range. Recent studies suggest that the radial artery may be more advantageous for investigating FMD because of an enhanced vasodilator response. This study therefore assessed the validity and repeatability of radial artery FMD (FMD-R) to evaluate its suitability for the noninvasive evaluation of endothelial function. Thirty-three healthy subjects were recruited over a period of 11 months. Intra- and inter-reader reproducibilities were measured with high-resolution ultrasound at 4 time points: twice 1 morning (1 to 3 hours apart) and twice again within 7 days (range 4 to 9 days between visits). Conduit endothelial-dependent and -independent vasomotion were assessed by responses to reactive hyperemia and nitroglycerin, respectively. FMD-R measurements demonstrated significant intra- and interday variabilities (intraclass correlation coefficients [ICCs] 0.38 and 0.23, p = 0.04 and 0.12, respectively). Bland-Altman plots confirmed the test-retest variation in FMD-R. In contrast, radial artery diameter measurements (intra- and inter-reader) demonstrated a high degree of repeatability (interstudy ICC >0.8, p <0.0001). The number of subjects needed to detect a treatment difference of 2% in FMD-R with a p value of 0.05 and a power of 0.80 would be 118 in a crossover design and 234 in a parallel design for assessing group changes. In conclusion, these findings show that FMD-R is highly variable within subjects, even in a healthy population, after adjusting for multiple technical factors and implies biologic variation in radial artery tone.

Effect of short-term weight loss on the metabolic syndrome and conduit vascular endothelial function in overweight adults.

Impaired vascular endothelial function may be an important mechanism linking obesity to increased cardiovascular risk. We investigated whether short-term weight loss improves conduit artery endothelial dysfunction in overweight adults. Forty-three otherwise healthy overweight patients with a body mass index > or =27 kg/m(2) completed an open-label 3-month trial consisting of a calorie-restricted diet and 120 mg of orlistat taken 3 times daily with meals. Endothelial function and parameters of the metabolic syndrome were measured before and after intervention. Subjects lost 6.6 +/- 3.4% of their body weight. Low-density lipoprotein cholesterol, low-density lipoprotein concentration, fasting insulin, and leptin decreased significantly (all p <0.009), and C-reactive protein decreased (p = 0.22). Conduit vascular function did not change as assessed by flow-mediated dilation (3.86 +/- 3.54 vs 3.74 +/- 3.78%, p = 0.86) and nitroglycerin-mediated dilation (17.18 +/- 5.89 vs 18.87 +/- 7.11%, p = 0.13) of the brachial artery. A moderate degree of weight reduction over 3 months improved the metabolic syndrome profile but not the vascular dysfunction associated with uncomplicated obesity.

Endothelial cell apoptosis in systemic lupus erythematosus: a common pathway for abnormal vascular function and thrombosis propensity.

Women with systemic lupus erythematosus (SLE) are at risk for premature atherothrombosis independent of Framingham risk factors. We investigated whether endothelial cell (EC) apoptosis predicts abnormal vasomotor tone and contributes to circulating tissue factor (TF) levels in this disease. Brachial artery flow-mediated dilation (FMD) and nitroglycerin-mediated dilation were determined in women with SLE, healthy control subjects, and subjects with coronary artery disease (CAD) (n = 43/group). Quantification of circulating apoptotic ECs was performed by flow cytometry (CD146(+) cells that stained for Annexin V [CD146(AnnV+)]) and immunofluorescent microscopy. Plasma TF was measured by enzyme-linked immunosorbent assay (ELISA). Compared with healthy control and CAD subjects, patients with SLE had higher numbers of circulating CD146(AnnV+) cells (10 +/- 3, 18 +/- 5, and 89 +/- 32 cells/mL, respectively, mean +/- SEM; P <.01). Increased CD146(AnnV+) cells correlated strongly with abnormal vascular function (P =.037). After adjusting for known predictors of endothelial function, CD146(AnnV+) was the only variable that predicted FMD (beta = -4.5, P <.001). Increased CD146(AnnV+) was strongly associated with elevated levels of circulating TF (r =.46, P =.002). Circulating apoptotic ECs are elevated in young women with SLE and strongly correlate with markedly abnormal vascular function and elevated TF levels. Heightened endothelial apoptosis may represent an important mechanism for development of atherothrombosis in SLE.

Effects of cilostazol in patients with Raynaud's syndrome.

Raynaud's syndrome (RS), which is characterized by recurrent episodes of vasospasm with exposure to cold, may occur alone (primary RS) or in association with connective tissue diseases or other underlying conditions (secondary RS). We investigated the effect of cilostazol on vessel wall responses in RS. Patients were diagnosed (primary or secondary RS associated with connective tissue diseases) and randomized to placebo or cilostazol 100 mg twice daily for 6 weeks in a double-blind manner. Brachial artery vasoreactivity, laser Doppler fluxmetry, and cold pressor testing (CPT) were performed at study initiation and completion. Symptoms were assessed using standardized questionnaires. Forty subjects completed the study (19 with primary RS and 21 with secondary RS). Cilostazol significantly increased the mean brachial artery diameter at 6 weeks (primary RS, p = 0.006; secondary RS, p = 0.06). There was no change in median flow-mediated dilation (FMD) with cilostazol in primary RS (25th, 75th percentiles) (4.06% [2.5, 6.1] to -0.77% [-2.4, 3.4] or secondary RS (2.2% [0.05, 6.3] to 2.95% [1.7, 7.4]). There were no changes in nitroglycerin-mediated dilation or microvascular flow indexes in either cohort. In patients with primary RS, cilostazol treatment yielded a positive change in the slope of brachial responsiveness to CPT (increase of 0.32 mm/min; p = 0.002 vs placebo). Cilostazol treatment remained significantly associated with increased brachial artery diameter when controlling for baseline values (p = 0.018). Cilostazol increased conduit vessel diameter in patients with primary and secondary RS, with a favorable impact on conduit vessel responsiveness to cold in patients with primary RS without affecting microvascular flow or symptoms.

Increased asymmetric dimethylarginine and endothelin 1 levels in secondary Raynaud's phenomenon: implications for vascular dysfunction and progression of disease.

OBJECTIVE: To compare microvascular and macrovascular functions in a cohort of patients with primary and secondary Raynaud's phenomenon (RP) who were matched for demographic, risk factor, and severity profiles. METHODS: Forty patients with primary or secondary RP matched for vascular risk factors and severity scores underwent testing of endothelial function and cold pressor responsiveness of the brachial artery. Microvascular perfusion of the digital vasculature was assessed using laser Doppler fluxmetry in response to reactive hyperemia. Plasma was assayed for endothelin 1 (ET-1), asymmetric dimethylarginine (ADMA), intercellular adhesion molecule 1, vascular cell adhesion molecule 1 (VCAM-1), and monocyte chemoattractant protein 1 (MCP-1). RESULTS: Patients with RP had abnormal vasoconstrictor responses to cold pressor tests (CPT) that were similar in primary and secondary RP. There were no differences in median flow-mediated and nitroglycerin-mediated dilation or CPT of the brachial artery in the 2 populations. Patients with secondary RP were characterized by abnormalities in microvascular responses to reactive hyperemia, with a reduction in area under the curve adjusted for baseline perfusion, but not in time to peak response or peak perfusion ratio. Plasma ET-1, ADMA, VCAM-1, and MCP-1 levels were significantly elevated in secondary RP compared with primary RP. There was a significant negative correlation between ET-1 and ADMA values and measures of microvascular perfusion but not macrovascular endothelial function. CONCLUSION: Secondary RP is characterized by elevations in plasma ET-1 and ADMA levels that may contribute to alterations in cutaneous microvascular function.

Altered cutaneous microvascular responses to reactive hyperaemia in coronary artery disease: a comparative study with conduit vessel responses.

Cutaneous microvascular responses to physiological stimuli are currently being investigated as indices of vascular function and to monitor responses to therapy. We attempted to systematically assess various microvascular cutaneous flow indices in response to reactive hyperaemia in control subjects and in patients with coronary artery disease (CAD), and to correlate these with brachial artery flow-mediated dilation (FMD). Groups of 24 healthy controls and 24 subjects with CAD underwent sequential brachial FMD determination in the dominant arm, and laser Doppler imaging to assess skin blood flow in the contralateral arm in response to reactive hyperaemia induced by cuff inflation and release. Laser Doppler values were expressed as: (a) AUC(5 min) (area under the curve over 5 min of release), (b) time to peak response, (c) % reactive hyperaemia, and (d) peak perfusion ratio. As expected, FMD was attenuated in CAD patients compared with controls (1.85+/-4.29% compared with 4.30+/-4.00%; P=0.05). Percentage reactive hyperaemia (CAD, 294+/-290%; controls, 501+/-344%; P=0.04) and the time to peak response as measured by laser Doppler imaging (CAD, 16.84+/-9.61 s; controls, 9.13+/-4.43 s; P=0.001) were significantly different between the CAD and control groups, while AUC(5 min) and the peak perfusion ratio did not show significant differences. Receiver operator curves for sensitivity/specificity analysis suggested that the time to peak response derived by laser Doppler imaging was superior to FMD for the diagnosis of CAD, with an overall specificity of 91.3% (positive predictive value of 89.4%) and a sensitivity of 73.7% (negative predictive value of 77.6%). In conclusion, laser Doppler-derived indices of microvascular flow do not correlate with conduit vessel responses. However, a time to peak response of >10 s as measured by laser Doppler imaging offers superior specificity for the diagnosis of CAD compared with brachial FMD.

Impaired vasoreactivity despite an increase in plasma nitrite in patients with abdominal aortic aneurysms.

OBJECTIVE: This investigation was designed to determine whether differences in vasoreactivity occur in patients with abdominal aortic aneurysms (AAAs) as compared with patients with peripheral arterial occlusive disease (PAOD) or individuals (controls) without known vascular disease. METHODS: Brachial artery vasoreactivity was assessed in a blinded fashion, after endothelium-dependent (ED) and endothelium-independent (EI) flow-mediated vasodilation, in age-matched, male patients with AAAs (n = 11) or PAOD (n = 9) or in controls (n = 10). There were no significant differences in prestudy systolic or diastolic blood pressure, body mass index, or antilipidemic medications among the groups studied. Exclusion criteria included diabetes and tobacco use within 3 months. Quantitative ultrasound scan measurements of brachial artery diameters were performed at rest and after either forearm ischemia (ED) or administration of 0.4 mg sublingual nitroglycerin (EI). Plasma nitric oxide (NO(X) = NO(2) + NO(3)) was measured with the Saville assay. Asymmetric dimethylarginine, an endogenous inhibitor of NO(X) synthase, was measured with liquid chromatography. RESULTS: Initial brachial artery diameters were not significantly different among the groups studied (4.85 +/- 0.18 mm for AAA group, 4.82 +/- 0.17 mm for PAOD group, 4.68 +/- 0.20 mm for controls). ED and EI vasodilation was significantly less (P =.02 and.03, respectively) in the AAA group (-1.71 +/- 1.52 and 8.33 +/- 1.13, respectively) when compared with the controls (2.96 +/- 1.04 and 13.88 +/- 2.16, respectively). However, plasma NO(X) was significantly increased (P =.01) in the AAA group (7.86 +/- 0.85 micromol/L) as compared with both controls (5.13 +/- 0.63 micromol/L) and PAOD (4.85 +/- 0.46 micromol/L). Asymmetric dimethylarginine levels were decreased in the AAA group (0.34 +/- 0.05 micromol/L) as compared with the PAOD group (0.46 +/- 0.09 micromol/L). No correlation existed between aneurysm size and ED or EI vasodilation or plasma NO(X). CONCLUSION: This study is the first to document a divergence between ED and EI vasoreactivity and systemic NO metabolites in patients with AAAs. It is speculated that a dysfunctional vessel wall response, rather than a lack of NO, may be important in the pathogenesis of AAAs.