Interaction between vascular dysfunction and cardiac mass increases the risk of cardiovascular outcomes in essential hypertension

Mechanisms and Clinical Implications of Endothelial Dysfunction in Arterial Hypertension

The endothelium is composed of a monolayer of endothelial cells, lining the interior surface of blood and lymphatic vessels. Endothelial cells display important homeostatic functions, since they are able to respond to humoral and hemodynamic stimuli. Thus, endothelial dysfunction has been proposed as a key and early pathogenic mechanism in many clinical conditions. Given the relevant repercussions on cardiovascular risk, the complex interplay between endothelial dysfunction and systemic arterial hypertension has been a matter of study in recent years. Numerous articles have been published on this issue, all of which contribute to providing an interesting insight into the molecular mechanisms of endothelial dysfunction in arterial hypertension and its role as a biomarker of inflammation, oxidative stress, and vascular disease. The prognostic and therapeutic implications of endothelial dysfunction have also been analyzed in this clinical setting, with interesting new findings and potential applications in clinical practice and future research. The aim of this review is to summarize the pathophysiology of the relationship between endothelial dysfunction and systemic arterial hypertension, with a focus on the personalized pharmacological and rehabilitation strategies targeting endothelial dysfunction while treating hypertension and cardiovascular comorbidities.

Endothelial progenitor cells predict vascular damage progression in naive hypertensive patients according to sex

Low levels of endothelial progenitor cells (EPCs) are associated with cardiovascular (CV) morbidity and mortality. Early indicators of vascular damage represent independent predictors of CV prognosis. The aim of this study was to evaluate the possible association of EPCs and circulating cytokine levels with vascular damage markers in naive hypertensive patients according to sex and to evaluate the role of EPCs in vascular damage progression. We enrolled 60 subjects; circulating EPCs were determined by cytometric analysis, and serum cytokines were determined by chemiluminescence microarray technology. Endothelial function was estimated with the measurement of the reactive hyperemia index (RHI), arterial stiffness (AS) was evaluated with the measurement of carotid-femoral pulse wave velocity (PWV) and carotid intima-media thickness (IMT) was determined by a high-resolution ultrasound B-mode system. Patients were evaluated at baseline and after an average follow-up of 3.0 ± 0.6 years. RHI was correlated with EPCs and inversely related to HOMA, TNF-α, IL-6, hs-CRP, and IL-1β. PWV was positively correlated with HOMA, TNF-α, IL-6, IL-1β, and hs-CRP, and it was inversely related to EPCs. An inverse relationship was observed between c-IMT and EPCs and e-GFR. EPCs were the major predictor of the RHI and PWV. After adjustment for vascular index basal values and the other covariates, EPCs explained 17.0%, 27.7%, and 10.6% of the variability in ΔRHI, ΔPWV, and Δc-IMT at follow-up, respectively. Our study results support the hypothesis of an etiological link between circulating EPCs and morphofunctional vascular parameters in hypertensive subjects. Of interest, circulating EPCs, after adjusting for possible confounding factors, may indicate vascular damage progression.

New-Onset Diabetes, Endothelial Dysfunction, and Cardiovascular Outcomes in Hypertensive Patients: An Illness-Event Model Analysis

Background. Insulin resistance and endothelial dysfunction are common findings in hypertensives, both predisposing to a higher risk of diabetes and cardiovascular events. We designed this study to evaluate the role of endothelial dysfunction in three pathogenetic pathways: (1) from baseline to cardiovascular events, (2) from baseline to diabetes, and (3) from new-onset diabetes to cardiovascular events. Methods. We enrolled 653 Caucasian never-treated hypertensives. Endothelial dysfunction was investigated by strain-gauge plethysmography; incident diabetes and cardiovascular events were evaluated by an illness-event model analysis. Results. During the follow-up (median 113 months), we documented 191 new cardiovascular events and 92 new cases of diabetes. In a multiple Cox regression analysis, acetylcholine-stimulated forearm blood flow [100% decrease, hazard ratio: 2.42 (95% confidence interval = 1.72–3.40)] and serum high-sensitivity C-reactive protein [hazard ratio: 1.30 (95% confidence interval = 1.21–1.40)] had an independent association with cardiovascular outcomes. The incidence rate of cardiovascular outcomes in diabetes-developer patients was higher than in the diabetes-free ones (34.9 vs. 2.5 events per 100 persons-year). In an illness-event model, a 100% decrease in forearm blood flow was associated with a 55.5% hazard ratio increase (hazard ratio: 1.56, 95% confidence interval: 1.33–1.82) of transition 1 (from baseline status to cardiovascular events) and to an almost doubled increase (hazard ratio: 2.54, 95% CI: 2.00–3.25) of the risk of transition 2 (from baseline status to diabetes). No such effects were found in transition 3 (from diabetes to cardiovascular events). Conclusions. Endothelial dysfunction plays a primary role in the pathways leading to diabetes and cardiovascular events in hypertensives. When diabetes is overt, endothelial dysfunction has no predictive value for subsequent cardiovascular events.

Vitamin D and Subclinical Cardiovascular Damage in Essential Hypertension

Vitamin D deficiency is linked to cardiac dysfunction, vascular remodeling, metabolic syndrome and insulin resistance (IR). The aim of the present study was to evaluate the association between vitamin D levels and cardiovascular (CV) organ damage in a large cohort of newly diagnosed treatment-naïve hypertensive patients, and the role of IR in this context. We enrolled 500 Caucasian individuals, without CV or renal complications. Subjects underwent a complete evaluation and measurements of vitamin D, standard laboratory determinations and instrumental examination, including echocardiography and applanation tonometry. Linear regression analyses were performed to assess the correlation between pulse wave velocity (PWV) and left ventricular mass index (LVMI) with different covariates. PWV was significantly correlated with age (p < 0.0001), LDL cholesterol (p < 0.0001), BMI (p = 0.001), pulse pressure (PP) (p = 0.005) and high sensitivity C-reactive protein (hs-CRP) (p = 0.006), while an inverse correlation was observed with vitamin D levels (p < 0.0001), Matsuda index (p < 0.0001) and estimated glomerular filtration ratio (e-GFR) (p = 0.006). LVMI significantly correlated with PP (p < 0.0001), hs-CRP (p < 0, 0001) and age (p = 0.001), while an inverse relationship was observed with vitamin D levels (p < 0.0001), Matsuda’s insulin sensitivity index (ISI) (p < 0.0001) and e-GFR (p < 0.0001). Vitamin D was the strongest predictor of PWV and LVMI, explaining, respectively, 28.3% and 19.1% of their variation. Our study suggests that low vitamin D might be a biomarker of end-organ damage.

Endothelial dysfunction and C-reactive protein predict the incidence of heart failure in hypertensive patients

Aims

Endothelial dysfunction and heart failure are associated, but no prospective studies demonstrated that impaired endothelium‐dependent vasodilation predicts incident heart failure. We designed this study to test whether endothelial dysfunction is associated with incident heart failure in a group of hypertensives.

Methods and results

We enrolled 735 White never‐treated hypertensive outpatients free from heart failure, diabetes, chronic kidney disease, and previous cardiovascular events. Endothelium‐dependent vasodilation was investigated by intra‐arterial infusion of acetylcholine, and laboratory determinations were obtained by standard procedures. During the follow‐up [median 114 months (range 26–206)], there were 208 new cases of heart failure (3.1 events/100 patient‐years). Dividing the study population in progressors and non‐progressors, we observed that progressors were older, showed a higher prevalence of being female, and had a higher baseline heart rate, glucose, insulin, Homeostatic Model Assessment (HOMA), creatinine, and high‐sensitivity C‐reactive protein (hs‐CRP) mean values, while estimated glomerular filtration rate and maximal acetylcholine‐stimulated forearm blood flow were lower. In the multiple Cox regression analysis, female gender [hazard ratio (HR) = 1.454, 95% CI = 1.067–1.981], fasting glucose (HR = 1.186, 95% CI = 1.038–1.357), hs‐CRP (HR = 1.162, 95% CI = 1.072–1.259), HOMA (HR = 1.124, 95% CI = 1.037–1.219), acetylcholine‐stimulated forearm blood flow (HR = 0.779, 95% CI = 0.695–0.874), and estimated glomerular filtration rate (HR = 0.767, 95% CI = 0.693–0.849) maintained an independent association with the outcome. Successively, testing the interaction between forearm blood flow and hs‐CRP, we observed that patients who have hs‐CRP values above the median and forearm blood flow under the median show a higher risk of developing heart failure (HR = 7.699, 95% CI = 4.407–13.451).

Conclusions

The present data demonstrate that an impaired endothelium‐dependent vasodilation and hs‐CRP predict development of incident heart failure in hypertensives.

Different Patterns of Left Ventricular Hypertrophy in Metabolically Healthy and Insulin-Resistant Obese Subjects

Obese subjects showed different cardiovascular risk depending by different insulin sensitivity status. We investigated the difference in left ventricular mass and geometry between metabolically healthy (MHO) and unhealthy (MUHO) obese subjects. From a cohort of 876 obese subjects (48.3 ± 14.1 years) without cardio-metabolic disease and stratified according to increasing values of Matsuda index after 75 g oral glucose tolerance test, we defined MHO (n = 292) those in the upper tertile and MUHO (n = 292) those in the lower tertile. All participants underwent echocardiographic measurements. Left ventricular mass was calculated by Devereux equation and normalized by height^2,7 and left ventricular hypertrophy (LVH) was defined by values >44 g/m^2.7 for females and >48 g/m^2.7 for males. Left ventricular geometric pattern was defined as concentric or eccentric if relative wall thickness was higher or lower than 0.42, respectively. MHO developed more commonly a concentric remodeling (19.9 vs. 9.9%; p = 0.001) and had a reduced risk for LVH (OR 0.46; p < 0.0001) than MUHO, in which the eccentric type was more prevalent (40.4 vs. 5.1%; p < 0.0001). We demonstrated that obese subjects-matched for age, gender and BMI-have different left ventricular mass and geometry due to different insulin sensitivity status, suggesting that diverse metabolic phenotypes lead to alternative myocardial adaptation.

Metabolic and vascular effects of silybin in hypertensive patients with high 1-h post-load plasma glucose

Hypertensive patients with normal glucose tolerance (NGT) but 1-h post-load plasma glucose ≥ 155 mg/dl (1-h high), during an oral glucose tolerance test (OGTT), show higher insulin resistance and multiple target organ damages. Experimental and clinical studies demonstrate that silybin presents anti-inflammatory and metabolic effects, improving insulin resistance and endothelial dysfunction. This study aims to evaluate the effects of the complex silybin-vitamin E and phospholipids on inflammatory, metabolic and vascular parameters in NGT 1-h high hypertensive patients. This is a pilot, single arm, interventional, longitudinal study enrolling 50 Caucasian NGT 1-h high hypertensive outpatients, 27 men and 23 women, age range 42-60 years (mean + SD = 52 ± 7). After 6 months of silybin intake, there is a significant improvement in metabolic profile. The glucose response during OGTT significantly improves (AUCglucose_0-120 309.6 ± 63.4 at baseline vs 254.6 ± 35.5 at the follow-up, ∆ = - 55, 95% CI from - 67 to - 43, p < 0.0001), so as insulin response (AUCinsulin_0-120 238.2 ± 99.1 vs 159.3 ± 44.9, ∆ = - 78.9, 95% CI from - 100.0 to - 57.8, p < 0.0001), in accordance with the increase of insulin sensitivity index Matsuda. Silybin intake is associated with a significant reduction of both clinical and central systolic blood pressure, with betterment in clinical and central pulse pressure and reduction of arterial stiffness parameters. In conclusion, this study demonstrates that silybin may improve the metabolic aspect and vascular damage in NGT 1-h high hypertensive patients who are at higher metabolic and cardiovascular risk. Thus, in these patients, silybin might strengthen the effect of antihypertensive drugs giving further cardiovascular protection.

Assessment of left atrium and diastolic dysfunction in patients with hypertensive retinopathy: A real-time three-dimensional echocardiography-based study

The fundoscopic examination of hypertensive patients, which is established hypertension-related target organ damage (TOD), tends to be underutilized in clinical practice. We sought to investigate the relationship between retinal alterations and left atrium (LA) volumes by means of real-time three-dimensional echocardiography (RT3DE). Our population consisted of 88 consecutive essential hypertensive patients (age 59.2 ± 1.2 years, 35 males). All subjects underwent a fundoscopy examination and were distributed into four groups according to the Keith-Wagener-Barker (KWB) classification. The four groups (KWB grades 0-3: including 26, 20, 26, and 16 patients, respectively) did not differ with regard to age, gender, or metabolic profile. There were no significant differences between groups with regard to parameters reflecting LV systolic function and diastolic dysfunction (DD) in two-dimensional echocardiography (2DE). Nevertheless, patients in the higher KWB category had higher values of LA volumes (LA maximal volume index, LA minimal volume index, preatrial contraction volume index, LA total stroke volume index, LA active stroke volume index, p < 0.001) regarding RT3DE. There is also a significant relationship between LA active stroke volume index (ASVI) and duration of hypertension (HT) (r: 0.68, p < 0.001). In the logistic regression analysis, ASVI was independent predictors of LV DD in patients with arterial hypertension (HT). Patients with arterial HT were found to have increased LA volumes and impaired diastolic functions. Assessment of the arterial HT patient by using RT3DE atrial volume analysis may facilitate early recognition of TOD, which is such a crucial determinant of cardiovascular mortality and morbidity.

Additive Effect of Non-Alcoholic Fatty Liver Disease on Metabolic Syndrome-Related Endothelial Dysfunction in Hypertensive Patients

Metabolic syndrome (MS) is characterized by an increased risk of incident diabetes and cardiovascular (CV) events, identifying insulin resistance (IR) and endothelial dysfunction as key elements. Moreover, non-alcoholic fatty liver disease (NAFLD) is bidirectionally linked with MS as a consequence of metabolic and inflammatory abnormalities. We addressed the question if the evolution in NAFLD might worsen endothelium-dependent vasodilating response in MS hypertensives. We recruited 272 Caucasian newly-diagnosed never-treated hypertensive outpatients divided into three groups according to the presence/absence of MS alone or in combination with NAFLD. MS and NAFLD were defined according to the National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATPIII) and non-invasive fatty liver index, respectively. We determined IR by using the homeostasis model assessment (HOMA) index. Vascular function, as forearm blood flow (FBF), was determined through strain-gauge plethysmography after intra-arterial infusion of acetylcholine (ACh) and sodium nitroprusside. MS+NAFLD+ group showed worse metabolic, inflammatory and vascular profiles compared with MS−NAFLD− and MS+NAFLD−. HOMA resulted in being the strongest predictor of FBF both in the MS+NAFLD− and in the MS+NAFLD+ groups, accounting for 20.5% and 33.2% of its variation, respectively. In conclusion, we demonstrated that MS+NAFLD+ hypertensives show a worse endothelium-dependent vasodilation compared with MS+NAFLD−, allowing for consideration of NAFLD as an early marker of endothelial dysfunction in hypertensives.

Uric acid is an independent predictor of cardiovascular events in post-menopausal women

BACKGROUND

Uric acid (UA) is a risk factor for cardiovascular (CV) disease. In post-menopause UA levels are increased and strongly associated with subclinical organ damage. We investigated the prognostic significance of UA levels in predicting CV morbidity and mortality in post-menopausal women.

METHODS

We considered 645 post-menopausal outpatients not taking hormone replacement therapy or any drugs interfering with UA levels. We evaluated major adverse cardiovascular events (MACE) as primary endpoint, with coronary, stroke or total events as secondary endpoint. Survival curves for tertiles of UA were obtained by using the Kaplan-Meier and Mantel methods. Effect of prognostic factors on survival was evaluated by multivariable Cox regression model, considering P<0.05 as statistically significant.

RESULTS

During a mean (SD) follow-up at 72.5 (23.5) months, there were 90 new CV events (2.31%): 62 coronary and 28 cerebrovascular events. The rate of nonfatal CV events (3.15% versus 2.03% and 1.52%, P=0.009) as well as that of MACE (3.23% versus 2.11% and 1.59%, P=0.011) were significantly higher in the third tertile than in the other two groups. Interestingly, cerebrovascular (1.15% versus 0.62% and 0.30%, P=0.027) but not coronary events were significantly different among the three groups. In the Cox regression model, UA was independently and strongly associated with the incident risk of MACE (HR=1.248, P=0.001), cerebrovascular (HR=1.657, P<0.0001) and total events (HR=1.391, P<0.0001).

CONCLUSIONS

In post-menopause, independently of other CV risk factors and menopause duration, UA levels are associated with increased risk of death and MACE, in particular cerebrovascular but not coronary events.

Renal disease and left atrial remodeling predict atrial fibrillation in patients with cardiovascular risk factors

OBJECTIVES

In this prospective population-based study, we tested the possible interaction between chronic kidney disease (CKD) and left atrium volume index (LAVI) in predicting incident atrial fibrillation (AF).

METHODS

We enrolled 3549 Caucasian subjects, 1829 men and 1720 women, aged 60.7 ± 10.6 years, without baseline AF and thyroid disorders. Echocardiographic left ventricular mass and LAVI were measured. Renal function was calculated by estimated glomerular filtration rate (e-GFR). To test the effect of some clinical confounders on incident AF, we constructed different models including clinical and laboratory parameters. AF diagnosis was made by standard electrocardiogram or 24-h ECG-Holter, hospital discharge diagnoses, and by the all-clinical documentation.

RESULTS

During the follow-up (53.3 ± 18.1 months), 546 subjects developed AF (4.5 events/100 patient-years). Progressors to AF were older, had a higher body mass index, blood pressure, LDL-cholesterol, glucose, cardiac mass, and LAVI, and had lower e-GFR. Hypertension, metabolic syndrome, diabetes, cardiac hypertrophy and CKD were more common among AF cases than controls. In the final Cox regression model, variables that remained significantly associated with AF were: cardiac hypertrophy (HR=1.495, 95% CI=1.215-1.841), renal disease (HR=1.528, 95% CI=1.261-1.851), age (HR=1.586, 95% CI=1.461-1.725) and LAVI (HR=2.920, 95% CI=2.426-3.515). The interaction analysis demonstrated a synergic effect between CKD and cardiac hypertrophy (HR=4.040, 95% CI=2.661-6.133), as well as between CKD and LAVI (HR=4.875, 95% CI=2.699-8.805). The coexistence of all three subclinical organ damages significantly increases the arrhythmic risk (HR=7.185, 95% CI=5.041-10.240).

CONCLUSIONS

Our data demonstrate that LAVI and CKD significantly interact in a synergic manner in increasing AF risk.

Brachial artery diameter measurement: a tool to simplify non-invasive vascular assessment

AIM

The mechanisms of vascular remodeling have attracted great interest since it is a phenomenon related to cardiovascular diseases. We would like to examine studies that contributed to clarify the remodeling mechanisms, to explore the different faces of atherosclerosis process.

DATA SYNTHESIS

A number of invasive and non-invasive vascular assessment methods were developed, to detect the early sign of atherosclerosis. It became clear that the invasive tests were not applicable to large-scale studies. Consequently, a non-invasive test was developed. Studies showed that the endothelial function evaluation is a predictor of future cardiac events in individuals at cardiovascular risk and in those with established disease. However, analyzing several works, an interesting concept emerged, i.e., the inverse relation between endothelium-dependent dilation and vessel size, since large vessel tend not to dilate significantly. This notion emphasized the role of basal diameter on vascular response. In particular, as brachial artery diameter is the measure on which FMD is based, it could add more information in clinical evaluation, simplifying the assessment. Several studies showed that morphological change of brachial artery is a better indicator of the extent of coronary disease rather than FMD. Other studies showed that brachial diameter has predictive significance in the stratification of cardiovascular risk.

CONCLUSION

Brachial diameter is a useful and simple tool. It should be incorporated into the overall assessment of cardiovascular risk but further studies are warranted to determine the final place of brachial diameter assessment in routine clinical setting.

Oxidative stress and endothelial dysfunction in hypertension

Systemic arterial hypertension is a highly prevalent cardiovascular risk factor that causes significant morbidity and mortality, and is becoming an increasingly common health problem because of the increasing longevity and prevalence of predisposing factors such as sedentary lifestyle, obesity and nutritional habits. Further complicating the impact of this disease, mild and moderate hypertension are usually asymptomatic, and their presence (and the subsequent increase in cardiovascular risk) is often unrecognized. The pathophysiology of hypertension involves a complex interaction of multiple vascular effectors including the activation of the sympathetic nervous system, of the renin-angiotensin-aldosterone system and of the inflammatory mediators. Subsequent vasoconstriction and inflammation ensue, leading to vessel wall remodeling and, finally, to the formation of atherosclerotic lesions as the hallmark of advanced disease. Oxidative stress and endothelial dysfunction are consistently observed in hypertensive subjects, but emerging evidence suggests that they also have a causal role in the molecular processes leading to hypertension. Reactive oxygen species (ROS) may directly alter vascular function or cause changes in vascular tone by several mechanisms including altered nitric oxide (NO) bioavailability or signaling. ROS-producing enzymes involved in the increased vascular oxidative stress observed during hypertension include the NADPH oxidase, xanthine oxidase, the mitochondrial respiratory chain and an uncoupled endothelial NO synthase. In the current review, we will summarize our current understanding of the molecular mechanisms in the development of hypertension with an emphasis on oxidative stress and endothelial dysfunction.

Association between hemoglobin level and endothelial function in uncomplicated, untreated hypertensive patients

BACKGROUND AND OBJECTIVES

Hemoglobin (Hb) is an important nitric oxide (NO) buffer and a modulator of NO bioavailability. In addition, endothelial dysfunction is common in hypertensive patients, suggesting a pivotal role of hemoglobin concentration ([Hb]) in vascular function. To investigate the potential role of [Hb] in endothelium-dependent vasodilation, the relationship between Hb and endothelial function was tested in a group of patients with essential hypertension.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this retrospective study, 174 nonsmoking, uncomplicated, never-treated hypertensives were enrolled. Endothelium-dependent and -independent vasodilation was assessed by measurement of forearm blood flow response during intra-arterial infusion of increasing doses of acetylcholine (ACh) and sodium nitroprusside (SNP) using strain-gauge plethysmography. Correlation with established risk factors of endothelial dysfunction was performed.

RESULTS

The vasodilatory response to ACh was inversely (P < 0.001) related to [Hb], and this relationship was dose dependent (P < 0.001), being minimal at the lowest dose and maximal at the highest dose. No association was found between Hb and the vasodilatory response to SNP. In a multiple linear regression model adjusted for Framingham risk factors (age, sex, BP, cholesterol, body mass index, glucose) and emerging risk factors (homeostasis model assessment index, C-reactive protein, estimated GFR), [Hb] maintained a strong and independent link with the vasodilatory response to ACh (P < 0.001).

CONCLUSIONS

In a large group of nonsmoking untreated hypertensives, [Hb] is inversely related to forearm endothelium-dependent vasodilation. [Hb] should be taken into account, especially in conditions associated with low [Hb], when performing vascular function studies.

Increased left ventricular mass and diastolic dysfunction are associated with endothelial dysfunction in normotensive offspring of subjects with essential hypertension

OBJECTIVES

We aimed to investigate left ventricular (LV) morphology and function in normotensive offspring of subjects with essential hypertension (familial trait - FT), and to determine the association between LV mass and determinants of LV diastolic function and endothelium-dependent (NO-mediated) dilation of the brachial artery (BA).

MATERIALS AND METHODS

The study encompassed 76 volunteers of whom 44 were normotonics with FT aged 28-39 (mean 33) years and 32 age-matched controls without FT. LV mass and LV diastolic function was measured using conventional echocardiography and tissue Doppler imaging (TDI). LV diastolic filling properties were assessed and reported as the peak E/A wave ratio, and peak septal annular velocities (E(m) and E(m)/A(m) ratio) on TDI. Using high-resolution ultrasound, BA diameters at rest and during reactive hyperaemia (flow-mediated dilation--FMD) were measured.

RESULTS

In subjects with FT, the LV mass index was higher than in controls (92.14+/-24.02 vs 70.08+/-20.58); p<0.001). Offspring of hypertensive families had worse LV diastolic function than control subjects (lower E/A ratio, lower E(m) and E(m)/A(m) ratio; p<0.001). In subjects with FT, FMD was decreased compared with the controls (6.11+/-3.28% vs 10.20+/-2.07%; p<0.001). LV mass index and E(m)/A(m) ratio were associated with FMD (p<0.001).

CONCLUSIONS

In normotensive individuals with FT, LV morphological and functional changes were found. We demonstrated that an increase in LV mass and alterations in LV diastolic function are related to endothelial dysfunction.

Vascular permeability, blood pressure, and organ damage in primary hypertension

Sub-clinical organ damage is a strong independent predictor of cardiovascular mortality in primary hypertension, and its changes over time parallel those in risk of cardiovascular events. A better understanding of the pathogenetic mechanisms underlying the development of target organ damage may help us devise more effective therapeutic strategies. We therefore investigated the relationship between the presence of organ damage and some of its potential determinants, such as blood pressure severity and early atherosclerotic abnormalities. Thirty-seven untreated, non-diabetic hypertensive patients were enrolled. Target organ damage was assessed by albuminuria and left ventricular mass index; systemic vascular permeability was evaluated by transcapillary escape rate of albumin (TERalb); and blood pressure was measured by 24h ambulatory blood pressure monitoring. The albumin-to-creatinine ratio and left ventricular mass index were directly related to TERalb (r = 0.48, p = 0.003 and r = 0.39, p < 0.020, respectively) and 24-h systolic blood pressure values (r = 0.54, p < 0.001; r = 0.60, p < 0.001). The simultaneous occurrence of increased blood pressure load and TERalb was associated with higher left ventricular mass index values (p = 0.012) and entailed an increased risk of having at least one sign of damage (chi2 = 17.4; p < 0.001). Logistic regression analysis showed that the risk of presenting at least one sign of organ damage increased more than ten-fold when TERalb was above the median and more than five-fold with each 10 mmHg increase in 24-h systolic blood pressure. Blood pressure load and vascular permeability are potentially modifiable factors that are independently associated with the occurrence of sub-clinical signs of renal and cardiac damage in hypertensive patients.

Prognostic role of flow-mediated dilatation of the brachial artery in hypertensive patients

BACKGROUND

The prognostic role of endothelial dysfunction, as evaluated by flow-mediated vasodilatation of the brachial artery, has been demonstrated in patients at very high risk. We aimed to investigate whether flow-mediated vasodilatation predicts cardiovascular events in uncomplicated hypertensive patients.

METHODS AND RESULTS

A total of 172 prospectively identified uncomplicated hypertensive patients (age 56 +/- 8 years, 41% women, 48 with diabetes mellitus type 2) were studied. At baseline all patients were untreated and underwent baseline standard laboratory examination. A standard echocardiogram was performed for the evaluation of left ventricular anatomy and function and patients with systolic dysfunction or left ventricular wall motion abnormalities were excluded. Endothelial function was measured as flow-mediated vasodilatation of the brachial artery using high-resolution ultrasound. Patients were followed for 95 +/- 37 months (range 2-136 months). A first nonfatal or fatal cardiovascular event occurred in 32 patients. The incidence of cardiovascular events was 1.4 and 3.1 per 100 patient-years in patients with a flow-mediated vasodilatation below and above the median value (4.7%), respectively (P < 0.005 by the log-rank test). In Cox analysis, controlling for age, sex, glycemia, cholesterol, smoking, BMI, systolic and diastolic blood pressure at baseline and left ventricular mass index, a low flow-mediated vasodilatation conferred an increased risk of cardiovascular events (odds ratio 2.67, 95% confidence interval 1.17 to 6.1, P = 0.02).

CONCLUSION

The presence of endothelial dysfunction, as evaluated by flow-mediated vasodilatation of the brachial artery, identifies hypertensive patients at increased risk of nonfatal and fatal cardiovascular events.

Nitric oxide, tetrahydrobiopterin, oxidative stress, and endothelial dysfunction in hypertension

Endothelial dysfunction in the setting of cardiovascular risk factors such as hypercholesterolemia, diabetes mellitus, chronic smoking, as well hypertension, is, at least in part, dependent of the production of reactive oxygen species (ROS) and the subsequent decrease in vascular bioavailability of nitric oxide (NO). ROS-producing enzymes involved in increased oxidative stress within vascular tissue include NADPH oxidase, xanthine oxidase, and mitochondrial superoxide producing enzymes. Superoxide produced by the NADPH oxidase may react with NO, thereby stimulating the production of the NO/superoxide reaction product peroxynitrite. Peroxynitrite in turn has been shown to uncouple eNOS, therefore switching an antiatherosclerotic NO producing enzyme to an enzyme that may accelerate the atherosclerotic process by producing superoxide. Increased oxidative stress in the vasculature, however, is not restricted to the endothelium and also occurs within the smooth muscle cell layer. Increased superoxide production has important consequences with respect to signaling by the soluble guanylate cyclase and the cGMP-dependent kinase I, which activity and expression is regulated in a redox-sensitive fashion. The present review will summarize current concepts concerning eNOS uncoupling, with special focus on the role of tetrahydrobiopterin in mediating eNOS uncoupling.

Endothelial dysfunction and C-reactive protein are risk factors for diabetes in essential hypertension

OBJECTIVE

Type 2 diabetes and essential hypertension are major risk factors for cardiovascular diseases. Endothelial dysfunction is an early step in the development of atherosclerosis and has been demonstrated in hypertensive and diabetic patients.

RESEARCH DESIGN AND METHODS

We designed this study to determine whether forearm endothelial dysfunction is an independent predictor of type 2 diabetes in patients with essential hypertension. We enrolled 400 white never-treated hypertensive outpatients, free of type 2 diabetes at the time of the first evaluation. Endothelium-dependent vasodilation was investigated by intra-arterial infusion of acetylcholine. Insulin resistance was estimated by homeostasis model assessment.

RESULTS

During the follow-up (4.5 +/- 1.6 years), 44 patients developed type 2 diabetes. The event rate was 2.4 events/100 patient-years. In a multivariate Cox regression analysis, the peak percentage increase in acetylcholine-stimulated forearm blood flow (hazard ratio [HR] 0.77 [95% CI 0.61-0.99]; P = 0.04) and C-reactive protein (1.16 [1.03-1.32]; P = 0.01) resulted in the only independent predictors of type 2 diabetes.

CONCLUSIONS

An impaired vasodilatory response to acetylcholine predicts development of type 2 diabetes in patients with essential hypertension. Present data also extend recent findings regarding a possible inflammatory pathogenesis of type 2 diabetes and suggest a new approach in treatment of essential hypertension.

Increased expression of endothelial nitric oxide synthase and caveolin-1 in the aorta of rats with isoproterenol-induced cardiac hypertrophy

Isoproterenol-induced cardiac hypertrophy is associated with increased expression of endothelial nitric oxide synthase in the aorta but without signs of improved endothelial function. The aim was to examine the hypothesis that increased expression of eNOS allosteric inhibitor caveolin-1 could be associated with unimproved endothelium-dependent relaxations. Rats received isoproterenol (5 mg/kg body mass, i.p., n = 13) or its vehicle (n = 14) during 1 week. Systolic blood pressure (SBP) and heart rate (HR) were measured by the tail-cuff method. Expression of eNOS and caveolin-1 was measured using immunoblotting analysis. Relaxations of isolated aorta to acetylcholine and sodium nitroprusside were evaluated ex vivo. After 1 week of isoproterenol administration, basal SBP and HR were decreased (SBP 110 +/- 3 vs. 126 +/- 3 mmHg, p < 0.05; HR 342 +/- 8 vs. 366 +/- 6 beats/min, p < 0.05). Isoproterenol increased the mass of the left ventricle (+33% +/- 4% vs. control; p < 0.05) and right ventricle (+40% +/- 9%; p < 0.05). Isoproterenol administration increased the expression of eNOS (+53% +/- 12%; p < 0.05) and caveolin-1 (+54% +/- 20%, p < 0.05) in the aorta. Relaxation of isolated aorta to acetylcholine and sodium nitroprusside showed a trend towards a worsened endothelial function and a lower sensitivity to exogenous NO. Thus, 1 week of isoproterenol administration led to increased eNOS expression in the aorta without amelioration of endothelial vasorelaxation function. Concomitant increase in caveolin-1 expression may be responsible for this paradox.

Effect of interaction between left ventricular dysfunction and endothelial function in hypertension

Hypertension, one of the most important risk factors for cardiovascular diseases, is associated with both left ventricular hypertrophy and endothelial dysfunction. Both have been recently recognized as independent predictors of clinical events in different groups of patients. In fact, a dysfunctioning endothelium loses its antiatherosclerotic and antithrombotic action, and, therefore, promotes the atherosclerotic process. Similarly, cardiac hypertrophy is recognized as a powerful and independent risk factor for cardiovascular morbidity and mortality because it predisposes to arrhythmias and maximizes the consequences of acute myocardial ischemia. Recently, an evident interaction has been demonstrated between endothelial dysfunction and left ventricular mass. In particular, the coexistence of both left ventricular hypertrophy and endothelial dysfunction almost doubles the risk for future vascular events in hypertensives. Thus, in hypertensive patients, it is clinically useful to choose an aggressive therapeutic strategy--to reduce left ventricular mass and to improve endothelial function.

Endothelial dysfunction and oxidative stress in arterial hypertension

A large body of evidence indicates that endothelial dysfunction is a characteristic of patients with essential hypertension. By definition, endothelial dysfunction is a functional and reversible alteration of endothelial cells, resulting from impairment in nitric oxide (NO) availability and oxidative stress. Superoxide anion is a major determinant of NO biosynthesis and also acts as a vasoconstrictor. In addition, NO synthase (NOS) can generate superoxide rather than NO in response to atherogenic stimuli ("NOS uncoupling"). Under these circumstances, NOS may become a peroxynitrite generator, leading to a dramatic increase in oxidative stress, since peroxynitrite has additional detrimental effects on vascular function by lipid peroxidation. Increased levels of biomarkers of lipid peroxidation and oxidative stress have been found in patients with hypertension. In particular, patients with hypertension-related microvascular changes showed increased lipid peroxidation and platelet activation when compared with patients with absent or early signs of retinopathy. Furthermore, oxidant stress has been shown to play an important role in promoting a prothrombotic state in the vascular system. For all these reasons, endothelial dysfunction is evoked in hypertensive patients as promotor of vascular progressive damage and atherosclerotic and thrombotic complications through the enhanced oxidative stress of arterial walls. This broadens the cardiovascular risk of hypertensive patients and explains the insufficient role of the strict BP reduction in the prevention of vascular complications, thus opening up new perspectives on the antioxidant properties of currently available antihypertensive drugs and supplementation with antioxidant principles.

Serum digoxin concentration and outcomes in women with heart failure: A bi-directional effect and a possible effect modification by ejection fraction

BACKGROUND

The association between serum digoxin concentration (SDC) and outcomes in women with heart failure (HF) has not been well studied.

AIMS

To test the hypothesis that the effect of digoxin on outcomes in women with HF is bi-directional and dependent on SDC, as in men, and is modified by ejection fraction (EF).

METHODS

We studied 1366 female participants of the Digitalis Investigation Group trial in whom data on SDC (ng/ml) were available. We calculated adjusted odds ratios (AOR) and Bonferroni-adjusted 97.5% confidence intervals (CI) for various outcomes at a median follow up of 41 months, in all women and stratified by EF 35%.

RESULTS

Compared with placebo (26.9%), 40.3% with SDC> or =1.2 (AOR=1.80; CI=1.14-2.86; p=0.004) and 26.6% with SDC 0.5-1.1 (AOR=1.05; CI=0.73-1.51; p=0.762) died. Respective rates for HF-hospitalizations were: placebo (32.8%), SDC> or =1.2 (38.0%) and SDC 0.5-1.1 (25.5%). For women with EF<35% (N=677), SDC 0.5-1.1 lowered odds for HF-hospitalizations (AOR=0.63; CI=0.39-1.00; p=0.026) without increasing odds for death (AOR=0.77; CI=0.47-1.26; p=0.233). In women with EF> or =35% (N=689), SDC 0.5-1.1 had a borderline association with death (AOR=1.58; CI=0.92-2.72; p=0.058) but not with HF-hospitalization (AOR=0.95; CI=0.54-1.66; p=0.826).

CONCLUSIONS

As in men, in women with HF, digoxin has a bi-directional effect based on SDC, and the beneficial effects were significant only among women with EF<35%.