Endothelial dysfunction in patients with chronic heart failure is independently associated with increased incidence of hospitalization, cardiac transplantation, or death

More than skin deep: atherosclerosis as a systemic manifestation of psoriasis

There is now growing evidence that psoriasis, like other inflammatory diseases such as rheumatoid arthritis and systemic lupus erythematosus, is a systemic disorder that is associated with enhanced atherosclerosis and risk of coronary artery disease. Here we summarize the available epidemiological evidence for this association and analyse pathogenic features that are common to psoriasis and atherosclerosis. Further prospective studies are urgently needed to extend knowledge of the risk of cardiovascular morbidity and mortality in patients with psoriasis and to confirm the degree to which treatment of psoriasis reduces this risk. Nevertheless, existing data are sufficient to indicate that severe psoriasis should be more widely recognized as a potential risk factor for cardiovascular disease and should be considered with the established factors when formulating strategies for the management of cardiovascular risk.

Vascular endothelial function predicts mortality risk in patients with advanced ischaemic chronic heart failure

AIMS

Endothelial function is impaired in advanced chronic heart failure (ACHF) patients. We explored a possible association between endothelial function and subsequent mortality risk in ACHF.

METHODS AND RESULTS

We prospectively assessed brachial flow-mediated dilation (FMD) in 82 consecutive New York Heart Association class IV ischaemic ACHF patients with a mean left ventricular ejection fraction (LVEF) of 22 +/- 3%. Following overnight fasting and discontinuation of all medications for > or = 12 h, percent increase in FMD (%FMD) and nitroglycerin-mediated vasodilation were assessed using linear array ultrasound. All patients were followed for 14 +/- 2 months for adverse cardiovascular events, including death, hospitalization for CHF exacerbation, or myocardial infarction. Patients were divided into two groups: those with an FMD lesser than or equal to the median %FMD of 4.6% (n = 41) and those with an FMD above the median (n = 41). Both groups were comparable regarding cardiovascular risk factors, LVEF, and concomitant medications. During follow-up, 22 (53.6%) patients with FMD lesser than or equal to the median had composite adverse cardiovascular events compared with only eight patients (19.5%) with FMD above the median (P < 0.01). Furthermore, fiver deaths (12.1%) occurred in patients with FMD lesser than or equal to the median, compared with no deaths in patients with FMD above the median (P < 0.03). Cox regression analyses revealed that FMD was an independent predictor for these events.

CONCLUSION

Flow-mediated dilation is associated with increased mortality risk in ischaemic ACHF patients.

Central sympathetic overactivity: maladies and mechanisms

There is growing evidence to suggest that many disease states are accompanied by chronic elevations in sympathetic nerve activity. The present review will specifically focus on central sympathetic overactivity and highlight three main areas of interest: 1) the pathological consequences of excessive sympathetic nerve activity; 2) the potential role of centrally derived nitric oxide in the genesis of neural dysregulation in disease; and 3) the promise of several novel therapeutic strategies targeting central sympathetic overactivity. The findings from both animal and human studies will be discussed and integrated in an attempt to provide a concise update on current work and ideas in these important areas.

The failing diabetic heart: focus on diastolic left ventricular dysfunction

Diabetes mellitus (DM) is highly prevalent and is an important risk factor for congestive heart failure (HF). Increased left ventricular (LV) diastolic stiffness is recognized as the earliest manifestation of DM-induced LV dysfunction, but its pathophysiology remains incompletely understood. Mechanisms whereby DM increases LV diastolic stiffness differ between HF with normal LV ejection fraction (EF) (HFNEF) and HF with reduced LVEF (HFREF). In diabetic HFREF, fibrosis and deposition of advanced glycation end products (AGEs) are the most important contributors to high LV diastolic stiffness, whereas in diabetic HFNEF, elevated resting tension of hypertrophied cardiomyocytes is the most important contributor to high LV diastolic stiffness. As HF mortality remains high in DM despite proven efficacy of current treatments, better understanding of the pathophysiology of high LV diastolic stiffness could be beneficial for novel therapeutic strategies.

Role of xanthine oxidoreductase in cardiac nitroso-redox imbalance

Emerging evidence supports the importance of nitroso-redox balance in the cardiovascular system. Xanthine oxidoreductase (XOR) is a major oxidative enzyme and increased XOR activity, leading to both increased production of reactive oxygen species and uric acid, is implicated in heart failure. Within the heart, XOR activity stimulates cardiomyocyte hypertrophy, apoptosis, and impairs matrix structure. The underpinnings of these derangements can be linked not solely to oxidative stress, but may also involve the process of nitroso-redox imbalance. In this regard, XOR interacts with nitric oxide signaling at numerous levels, including a direct protein-protein interaction with neuronal nitric oxide synthase (NOS1) in the sarcoplasmic reticulum. Deficiency or translocation of NOS1 away from this microdomain leads to increased activity of XOR, which in turn impairs excitation-contraction coupling and myofilament calcium sensitivity. There is a mounting abundance of preclinical data supporting beneficial effects of inhibiting XOR, but translation to the clinic continues to be incomplete. A growing understanding of XOR and its role in nitroso-redox imbalance has great potential to lead to improved pathophysiologic insights and possibly therapeutic advances.

Circulating apoptotic progenitor cells in patients with congestive heart failure

Background

Circulating CD34+ endothelial progenitor cells (EPCs) are capable of differentiating into mature endothelial cells to assist in angiogenesis and vasculogenesis. We sought to quantify the numbers of apoptotic progenitors in patients with congestive heart failure.

Methods and Results

Peripheral blood mononuclear cells were isolated by Ficoll density-gradient from 58 patients with various degrees of heart failure and 23 matched controls. Apoptosis in progenitor CD34+ cells was assessed using the Annexin V-PE/PI detection kit, and FACS analysis was performed with triple staining for CD34, annexin-V and propidium iodide. The percentage of early and late apoptotic progenitor cells was determined in the subject groups and was correlated with clinical characteristics. While there was no significant difference in total CD34 positive cells or early apoptotic progenitors between control subjects and CHF patients (p = 0.42) or between severe and mild/moderate CHF groups (p = 0.544), there was an elevated number of late apoptotic progenitors in the severe CHF group compared with the mild/moderate CHF group (p =  0.03). Late apoptotic progenitors were significantly increased in CHF patients as compared to matched controls. There was also an inverse correlation between late apoptotic progenitors and ejection fraction (r = −0.252, p = 0.028) as well as a positive association with NYHA class (r = 0.223, p = 0.046).

Conclusion

Severe heart failure patients exhibited higher numbers of late apoptotic progenitors, and this was positively associated with NYHA class and negatively correlated with ejection fraction. This finding may shed light on the numerous factors governing the pathophysiology of CHF.

Activation of inducible NOS in peripheral vessels and outcomes in heart failure patients

BACKGROUND

Activation of inducible nitric oxide synthase (iNOS) has been reported in congestive heart failure (CHF) conditions. However, it is unknown whether activation of iNOS affects prognosis of CHF patients. We prospectively studied the influence of activation of iNOS in the forearm on the outcome of CHF patients.

METHODS AND RESULTS

Forearm blood flow (FBF) responses to 3 doses of acetylcholine (ACh) and nitroglycerin (NTG), and 4 doses of a selective iNOS inhibitor (aminoguanidine: Amn) and a nonselective NOS inhibitor (L-NMMA) were examined using plethysmography in 68 patients with CHF from idiopathic dilated cardiomyopathy. Plasma brain natriuretic peptide (BNP) and tumor necrosis factor-alpha (TNF-alpha) were also measured in all patients. During the mean follow-up period of 3.8 years, 25 patients were hospitalized for worsening heart failure and 9 of these patients died. Patients with adverse events had a diminished vasodilator response to ACh (P < .001) compared to patients without adverse events. Amn significantly decreased FBF (P < .001) in patients with adverse events, but not in patients without adverse events. FBF responses to NTG and L-NMMA were not significantly different between the 2 groups. When grouped by maximum FBF responses to each drug above and below the median value, multivariate Cox proportional hazards model analyses for cardiac event showed a significance in the FBF response to Amn (adjusted hazard ratio 5.89, P < .001). FBF responses to maximum dose of Amn significantly correlated with BNP and TNF-alpha levels (both P < .001).

CONCLUSIONS

CHF patients with vascular iNOS activation, as demonstrated by a greater vasoconstrictor response to Amn, had poor outcomes. Activation of iNOS in peripheral vessels, associated with proinflammatory cytokines in accordance to the severity of heart failure, is a marker for, or contributes to, adverse events in patients with CHF.

Plasma lipoprotein-associated phospholipase A2 levels in heart failure: association with mortality in the community

OBJECTIVE

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a useful inflammatory marker of cardiovascular risk, yet little is known of its prognostic role in heart failure (HF). We evaluated the association of Lp-PLA2 with mortality in subjects with HF and assessed its incremental value for risk discrimination over established risk factors and biomarkers.

METHODS

Residents of Olmsted County, MN, diagnosed with HF between September 2003 and April 2007 (n=646, mean age 76 years, 51% women) were prospectively enrolled and followed-up. Plasma Lp-PLA2 levels were measured at baseline and evaluated along with known risk indicators.

RESULTS

Lp-PLA2 was positively associated with male gender and low-density lipoprotein cholesterol and inversely associated with statin use and diabetes. During follow-up (median 21 months), 213 deaths occurred. Elevated Lp-PLA2 was associated with an increased risk of mortality (hazard ratio (HR)=1.57; 95% confidence interval (CI): 1.03-2.37; P=0.035, per 1-unit increase in the log-transformed values). The relationship differed markedly by age (P(interaction)=0.003), with a strong association in patients under 80 years (covariate-adjusted HR=3.83; 95% CI: 1.93-7.61; P<0.001) and none in older ones (covariate-adjusted HR=0.82; 95% CI: 0.44-1.51; P=0.55). For the younger subjects, an improvement in the model's discriminatory power was obtained by adding Lp-PLA2 to established risk indicators and biomarkers (area under the receiver operating characteristic curve, 0.709-0.744, P(difference)=0.008).

CONCLUSION

In this community-based cohort of patients with HF, Lp-PLA2 was strongly and independently associated with mortality and contributed incrementally to risk discrimination in patients under 80 years of age.

Increased muscle sympathetic nerve activity predicts mortality in heart failure patients

BACKGROUND

Previous studies have associated neurohumoral excitation, as estimated by plasma norepinephrine levels, with increased mortality in heart failure. However, the prognostic value of neurovascular interplay in heart failure (HF) is unknown. We tested the hypothesis that the muscle sympathetic nerve activity (MSNA) and forearm blood flow would predict mortality in chronic heart failure patients.

METHODS

One hundred and twenty two heart failure patients, NYHA II-IV, age 50+/-1 ys, LVEF 33+/-1%, and LVDD 7.1+/-0.2 mm, were followed up for one year. MSNA was directly measured from the peroneal nerve by microneurography. Forearm blood flow was obtained by venous occlusion plethysmography. The variables were analyzed by using univariate, stepwise multivariate Cox proportional hazards analysis, and Kaplan-Meier analysis.

RESULTS

After one year, 34 pts died from cardiac death. The univariate analysis showed that MSNA, forearm blood flow, LVDD, LVEF, and heart rate were significant predictors of mortality. The multivariate analysis showed that only MSNA (P=0.001) and forearm blood flow (P=0.003) were significant independent predictors of mortality. On the basis of median levels of MSNA, survival rate was significantly lower in pts with >49 bursts/min. Similarly, survival rate was significantly lower in pts with forearm blood flow <1.87 ml/min/100 ml (P=0.002).

CONCLUSION

MSNA and forearm blood flow predict mortality rate in patients with heart failure. It remains unknown whether therapies that specifically target these abnormalities will improve survival in heart failure.

Serum uric acid correlates with extracellular superoxide dismutase activity in patients with chronic heart failure

Increased serum uric acid has been identified as an independent risk factor for cardiovascular disease. However, because of its antioxidant capacity, uric acid may play a beneficial role in endothelial function. This paradoxical relationship between uric acid and endothelial function in chronic heart failure patients remains poorly understood. Thirty-eight chronic heart failure patients (New York Heart Association functional class II-III, mean age 58+/-10 years and mean left ventricular ejection fraction 25+/-8%) and twelve age-and-sex-matched healthy controls were studied. Chronic heart failure patients showed higher uric acid levels (7.3+/-2.3 mg/dL vs. 6.1+/-0.2 mg/dL, p<0.05) and lower extracellular superoxide dismutase activity (136+/-36 U ml(-1) min(-1) vs. 203+/-61 U ml(-1) min(-1), p<0.01) and endothelium-dependent vasodilatation (4.0+/-1.6% v. 9.1+/-3.0%, p<0.01) when compared with control subjects. In chronic heart failure patients, correlations between both uric acid levels and extracellular superoxide dismutase activity (r=0.45; p<0.01), and uric acid and endothelium-dependent vasodilatation (r=0.35; p=0.03) were detected. These correlations were not observed in healthy individuals, suggesting a positive effect of uric acid on endothelial function partially mediated by modulation of extracellular superoxide dismutase activity in chronic heart failure.

Angiotensin-converting enzyme inhibition improves vascular function in rheumatoid arthritis

BACKGROUND

The excess in cardiovascular risk in patients with rheumatoid arthritis provides a strong rationale for early therapeutical interventions. In view of the similarities between atherosclerosis and rheumatoid arthritis and the proven benefit of angiotensin-converting enzyme inhibitors in atherosclerotic vascular disease, it was the aim of the present study to delineate the impact of ramipril on endothelial function as well as on markers of inflammation and oxidative stress in patients with rheumatoid arthritis.

METHODS AND RESULTS

Eleven patients with rheumatoid arthritis were included in this randomized, double-blind, crossover study to receive ramipril in an uptitration design (2.5 to 10 mg) for 8 weeks followed by placebo, or vice versa, on top of standard antiinflammatory therapy. Endothelial function assessed by flow-mediated dilation of the brachial artery, markers of inflammation and oxidative stress, and disease activity were investigated at baseline and after each treatment period. Endothelial function assessed by flow-mediated dilation increased from 2.85+/-1.49% to 4.00+/-1.81% (P=0.017) after 8 weeks of therapy with ramipril but did not change with placebo (from 2.85+/-1.49% to 2.84+/-2.47%; P=0.88). Although systolic blood pressure and heart rate remained unaltered, diastolic blood pressure decreased slightly from 78+/-7 to 74+/-6 mm Hg (P=0.03). Tumor necrosis factor-alpha showed a significant inverse correlation with flow-mediated dilation (r=-0.408, P=0.02), and CD40 significantly decreased after ramipril therapy (P=0.049).

CONCLUSIONS

Angiotensin-converting enzyme inhibition with 10 mg/d ramipril for 8 weeks on top of current antiinflammatory treatment markedly improved endothelial function in patients with rheumatoid arthritis. This finding suggests that angiotensin-converting enzyme inhibition may provide a novel strategy to prevent cardiovascular events in these patients.

Advanced glycation end-products (AGEs) and heart failure: pathophysiology and clinical implications

Advanced glycation end-products (AGEs) are molecules formed during a non-enzymatic reaction between proteins and sugar residues, called the Maillard reaction. AGEs accumulate in the human body with age, and accumulation is accelerated in the presence of diabetes mellitus. In patients with diabetes, AGE accumulation is associated with the development of cardiac dysfunction. Enhanced AGE accumulation is not restricted to patients with diabetes, but can also occur in renal failure, enhanced states of oxidative stress, and by an increased intake of AGEs. Several lines of evidence suggest that AGEs are related to the development and progression of heart failure in non-diabetic patients as well. Preliminary small intervention studies with AGE cross-link breakers in heart failure patients have shown promising results. In this review, the role of AGEs in the development of heart failure and the role of AGE intervention as a possible treatment for heart failure are discussed.

Exercise training attenuates progressive decline in brachial artery reactivity in heart transplant recipients

BACKGROUND

Heart transplantation normalizes central hemodynamics, but endothelial dysfunction persists after transplantation.

METHODS

To investigate the effects of aerobic exercise on arterial function, oxidative stress, lipid profile, and sympathetic nervous system activity, 20 heart transplant recipients (age, 54.3 +/- 9.1 years; 17 men, 3 women) were randomly assigned to 12 weeks of supervised treadmill exercise (Trained; n = 10) or standard medical care (Control; n = 10). Supervised exercise was initiated at 8 weeks after transplant. Brachial artery reactivity was assessed using flow-mediated dilation.

RESULTS

The VO2 peak increased 26% in the Trained patients (15.4 +/- 4.3 vs 19.4 +/- 5.5 ml/kg/min; p < or = 0.05) but did not change in the Controls (16.2 +/- 5.2 vs 16.8 +/- 2.8 ml/kg/min; p > or = 0.05). Brachial artery flow-mediated dilation (10.1% +/- 6.1% vs 9.6% +/- 6.2%) and absolute brachial diameter (0.48 +/- 0.22 vs 0.42 +/- 0.24 mm) did not change in Trained patients, but brachial flow-mediated dilation (10.5% +/- 2.8% vs 7.9% +/- 5.1%) and the absolute change in brachial diameter (0.48 +/- 0.16 vs 0.36 +/- 0.24 mm) decreased significantly (p < or = 0.05) in the Control patients. Resting norepinephrine decreased significantly (p < or = 0.05) after training (0.32 +/- 0.19 vs 0.22 +/- 0.22 ng/ml), but there was a nonsignificant trend toward increased norepinephrine in the Controls (0.26 +/- 0.17 vs 0.53 +/- 0.41 ng/ml; p = 0.07). The lipid profile and marker of oxidative stress did not differ between the groups before or after the intervention.

CONCLUSIONS

To our knowledge, this is the first prospective, randomized study to investigate the effects of heart transplantation and aerobic exercise on peripheral artery function in the same cohort of heart transplant recipients. Brachial artery flow-mediated dilation increased early in the post-operative period. Aerobic exercise preserved but did not improve brachial artery flow-mediated dilation. Heart transplant recipients who did not participate in supervised exercise showed a progressive decline in brachial artery flow-mediated dilation.

Mineralocorticoid Receptor Blockade Improves Vasomotor Dysfunction and Vascular Oxidative Stress Early After Myocardial Infarction

Mineralocorticoid receptor blockade improves mortality early after myocardial infarction (MI). This study investigated the vascular effects of mineralocorticoid receptor blockade in the early phase postinfarction in rats. Starting immediately after coronary ligation, male Wistar rats were treated with placebo or eplerenone (100 mg/kg/d). After 7 days, hemodynamic assessment was performed and endothelial function was determined. Maximum acetylcholine-induced relaxation was significantly attenuated in aortic rings from rats with heart failure after MI, and ameliorated by eplerenone treatment. Endothelium-independent relaxation by DEA-NONOate was similar among the groups. Endothelial NO synthase phosphorylation was reduced in the aorta of MI rats and restored by eplerenone therapy. Angiotensin I-induced vasoconstriction as well as angiotensin-converting enzyme protein levels were enhanced in aortas from MI placebo rats, and reduced by mineralocorticoid receptor inhibition. Aortic reactive oxygen species formation as well as the expression of the NAD(P)H oxidase subunit p22(phox) were increased after MI and normalized in eplerenone treated rats. In conclusion, mineralocorticoid receptor antagonism improved endothelial dysfunction in the early phase post-MI. Underlying mechanisms involve inhibition of vascular angiotensin-converting enzyme upregulation and improvement of endothelial NO synthase-derived NO bioavailability.

Redox state, oxidative stress and endothelial dysfunction in heart failure: the puzzle of nitrate–thiol interaction

Endothelial dysfunction, a critical component in the progression of heart failure, may result from increased oxidative stress, secondary to activation of the adrenergic and the renin-angiotensin systems and to the production of inflammatory cytokines, which in turn contribute to reduced bioavailability of nitric oxide (NO). Oxidative stress, determined by excess production of reactive oxygen species and impairment in the antioxidant defence, is responsible for both the decline of diffusible NO and the decrease in the concentration of essential co-factors of NO synthases. Reactive oxygen species are formed from NO in the presence of oxidants and are involved in the nitration of protein tyrosine residue that can alter protein function. Recent studies re-addressed the impact of nitrate treatment in heart failure in view of the beneficial vascular and cellular effects of NO, and of the discovery of abnormalities in NO pathways in this disease. Concerns exist, however, on the safety of nitrates in this setting. Nitrates stimulate vascular superoxide anion production via activation of NADPH oxidase, and induction of uncoupling of NO synthase. Furthermore, by using donors of sulfhydryl groups, such as cysteine and glutathione, for NO production, nitrates may favour depletion of the intracellular thiol pool, thus impairing the antioxidant defence mechanisms.

Endothelial function, arterial stiffness and lipid lowering drugs

The endothelium is a dynamic organ that plays a pivotal role in cardiovascular homeostasis. Alteration in endothelial function precedes the development of atherosclerosis and contributes to its initiation, perpetuation and clinical manifestations. It has been suggested that the assessment of endothelial function could represent a barometer of vascular health that could be used to gauge cardiovascular risk. This review summarises the various methods used to assess endothelium-dependent vasodilatation and their potential prognostic implications. In addition, the techniques used to evaluate arterial stiffness are discussed. The latter is to some extent controlled by the endothelium and has been the subject of considerable research in recent years. This paper also discusses the effects of lipid lowering treatment on both endothelial function and arterial stiffness.

Targeting Heme-Oxidized Soluble Guanylate Cyclase in Experimental Heart Failure

Soluble guanylate cyclase is a heterodimeric enzyme with a prosthetic heme group that, on binding of its main ligand, NO, generates the second messenger cGMP. Unlike conventional nitrovasodilators, the novel direct NO- and heme-independent soluble guanylate cyclase activator BAY 58-2667 is devoid of non-cGMP actions, lacks tolerance development, and preferentially activates NO-insensitive heme-free or oxidized soluble guanylate cyclase. BAY 58-2667, therefore, represents a novel therapeutic advance in mediating vasodilation. To date, its cardiorenal actions in congestive heart failure (CHF) are undefined. We, therefore, hypothesized that BAY 58-2667 would have beneficial preload- and afterload-reducing actions in experimental severe CHF together with renal vasodilating properties. We assessed the cardiorenal actions of intravenous administration of 2 doses of BAY 58-2667 (0.1 and 0.3 μg/kg per minute, respectively) in a model of tachypacing-induced severe CHF. In CHF, BAY 58-2667 dose-dependently reduced mean arterial, right atrial, pulmonary artery, and pulmonary capillary wedge pressure (from baseline 19±1 to 12±2 mm Hg). Cardiac output (2.4±0.3 to 3.2±0.4 L/min) and renal blood flow increased. Glomerular filtration rate and sodium and water excretion were maintained. Consistent with cardiac unloading, atrial and B-type natriuretic peptide decreased. Plasma renin activity ( P =0.31) and aldosterone remained unchanged ( P =0.19). In summary, BAY 58-2667 in experimental CHF potently unloaded the heart, increased cardiac output and renal blood flow, and preserved glomerular filtration rate and sodium and water excretion without further neurohumoral activation. These beneficial properties make direct soluble guanylate cyclase stimulation with BAY 58-2667 a promising new therapeutic strategy for cardiovascular diseases, such as heart failure.

Circulating endothelial progenitor cells and clinical outcome in patients with congestive heart failure

BACKGROUND

Circulating endothelial progenitor cells (EPCs) are increased in conditions associated with ischaemia and can potentially support angiogenesis and vasculogenesis. EPC levels were also shown to predict outcome in patients with atherosclerotic vascular disease. We tested the hypothesis that circulating EPC can predict outcome in patients with congestive heart failure (CHF).

METHODS

EPC-colony-forming units were measured in the peripheral blood of 107 consecutive patients with CHF with New York Heart Association (NYHA) functional class II-IV. Serum levels of vascular endothelial growth factor (VEGF), N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) and high-sensitivity C-reactive protein (hsCRP) were also measured. End points were defined as CHF-related hospital admissions and all-cause mortality.

RESULTS

Age (p = 0.01), diabetes mellitus (p = 0.002) and EPC levels (p = 0.02) were found to be independent predictors of all-cause mortality. EPC levels did not predict CHF-related hospitalisations. EPC levels correlated positively with NYHA (p = 0.05, r = 0.19), but did not correlate with VEGF, NT-pro-BNP or hsCRP. EPC levels did not differ by the aetiology of CHF.

CONCLUSIONS

EPC levels are independent predictors of all-cause mortality among patients with CHF.

Exercise Intolerance in Adults with Congenital Heart Disease

This article describes the ways to assess exercise capacity in adults with congenital heart disease (ACHD) and the impact of exercise intolerance in the population. It also discusses the likely pathogenesis of exercise intolerance in ACHD, the similarities between ACHD and acquired heart failure, and potential therapeutic options.

Nitric oxide-dependent endothelial function and cardiovascular disease

Nitric oxide produced by three different isoforms of nitric oxide synthase (NOS) widely expressed in virtually all vascular cell types is mostly produced by the endothelial isoform (eNOS) in endothelial cells where it plays a crucial role in vascular tone and structure regulation. It also exerts an anti-inflammatory influence, inhibits platelets adhesion and aggregation, and prevents smooth muscle cells proliferation and migration. Several lines of evidence link endothelial dysfunction, characterized by decreased bioavailability of nitric oxide, with the development of many pathological conditions such as heart failure, hypertension, diabetes and atherosclerosis. This review focuses on nitric oxide-dependent endothelial dysfunction in cardiovascular diseases, its clinical detection and relevance, potential pathogenic mechanisms and possible therapies.

Use of a flow-mediated vasodilation technique to assess endothelial function in dogs

OBJECTIVE

To develop and assess the reproducibility of a protocol to noninvasively test endothelial function in dogs on the basis of the flow-mediated vasodilation (FMD) procedure used in humans.

ANIMALS

5 healthy spayed female dogs.

PROCEDURES

Luminal arterial diameter and blood flow velocity in the brachial and femoral arteries were measured with ultrasonography. The within-dog reproducibility of these ultrasonographic measurements was tested. An occlusion period of 1, 3, or 5 minutes with an inflatable cuff was used to create the FMD response. Measurements made at 15, 30, and 60 seconds following release of the occlusion were compared with measurements made immediately prior to each occlusion to assess the FMD response.

RESULTS

Within-dog reproducibility of measurements revealed moderate to high correlations. Change from baseline in luminal arterial diameter was most substantial when measured at 30 seconds following release of occlusion, whereas blood flow velocity changes were maximal when measured at 15 seconds following release. The brachial imaging site provided a larger number of significant FMD responses than the femoral site. The 3-minute occlusion period provided equal or better responses than the 5-minute occlusion period.

CONCLUSIONS AND CLINICAL RELEVANCE

Ultrasonographic measurement of the FMD responses was a feasible and reproducible technique and significant changes from baseline were detected. The FMD responses in dogs were most substantial when performed at the brachial artery with blood flow velocity and luminal arterial diameter changes from baseline measured at 15 and 30 seconds, respectively, following release of a 3-minute occlusion period.

Effect of angiotensin II type 1 receptor antagonism on endothelial function: role of bradykinin and nitric oxide

BACKGROUND

The important role of the endothelium for regulation of vascular tone, growth, inflammatory response, coagulation and thrombocyte adhesion has now been recognized. Endothelial function has largely been assessed as endothelium-dependent vasodilation, assuming that endothelium-dependent vasomotion represents a surrogate marker for other important endothelial functions. An important rational for this approach has been the observation that both endothelium-dependent vasomotion and other protective endothelial functions are at least partially mediated by nitric oxide. Accumulating clinical studies have now demonstrated a close and independent association of impaired endothelium-dependent vasodilation with cardiovascular events and prognosis. These findings have stimulated interest in treatment options to improve endothelial function in patients at high cardiovascular risk.

DISCUSSION

This article describes recent insights into endothelial effects of both angiotensin-converting enzyme (ACE) inhibition and angiotensin II type 1 (AT1) receptor blockade, which have both been shown to improve endothelial function (i.e. by increasing endothelial nitric oxide availability via bradykinin-dependent endothelial nitric oxide release). ACE has a high affinity for bradykinin and degrades the peptide, so ACE inhibition may increase bradykinin-dependent effects by preventing bradykinin degradation. Interestingly, AT1-receptor blockade appears to stimulate the bradykinin-nitric oxide pathway by increased angiotensin II type 2 receptor activation. Moreover, both treatment strategies prevent increased inactivation of endothelial nitric oxide by oxygen radicals, by reducing AT1-receptor-dependent activation of the oxidant enzyme NADPH oxidase and increasing the activity of the vascular antioxidant enzyme extracellular superoxide dismutase. These beneficial effects of ACE inhibition and AT1-receptor blockade are likely to contribute to their effects on cardiovascular events.

The latest generation of beta-blockers: New pharmacologic properties

beta-Blockers have generally demonstrated smaller reductions in cardiovascular events, compared with other antihypertensive classes, despite similar reductions in blood pressure. This may be due to the ineffectiveness of traditional beta-blockers, such as atenolol, in reducing central aortic pressure, a strong, independent predictor of cardiovascular outcome. However, the beta-blocker class is heterogeneous, and some newer beta-blockers, which exhibit vasodilatory effects independent of beta-blockade, provide beneficial effects on arterial stiffness and endothelial dysfunction, which may lead to reductions in central aortic pressure and improvements in clinical outcomes. For example, the vasodilating beta-blocker nebivolol was shown to improve forearm blood flow and arterial stiffness and, in a large clinical study, to significantly reduce morbidity and mortality, independent of left ventricular ejection fraction, among patients with chronic heart failure. Further research is warranted to investigate any potential differences between traditional and newer vasodilating beta-blockers on cardiovascular outcomes.

A review of isosorbide dinitrate and hydralazine in the management of heart failure in black patients, with a focus on a new fixed-dose combination

BACKGROUND

It is estimated that 25% to 30% of patients with heart failure (HE) in the United States are black. Compared with nonblack patients, black patients have a reduced ability to produce endogenous nitric oxide, which may be associated with enhanced responsiveness to drugs that increase the delivery of nitric oxide, such as nitrates. When used with nitrates, hydralazine (HYD) acts as an antioxidant and prevents development of nitrate tolerance.

OBJECTIVE

This article reviews the clinical pharmacology of isosorbide dinitrate (ISDN) and HYD and clinical trials of their use in the treatment of HF, with a particular focus on the new fixed-dose combination for the treatment of HF in black patients.

METHODS

Articles or abstracts reporting the results of randomized, double-blind, controlled studies of ISDN and HYD in HF were identified through a search of the English-language literature indexed on MEDLINE and Current Contents/Clinical Medicine from 1966 to February 5, 2005, using the terms hydralazine, isosorbide dinitrate, nitrates, and heart failure. The reference lists of identified articles were reviewed for additional publications. Selected information provided by the manufacturer was also reviewed.

RESULTS

The combination of ISDN and HYD was studied in 3 large randomized controlled trials, the first and second Vasodilator in Heart Failure trials (V-HeFT I and V-HeFT II), which included approximately 27% black men, and the African-American Heart Failure Trial (A-HeFT), which included 100% self-identified black patients of both sexes. In V-HeFT I, which compared ISDN 40 mg QID and HYD 75 mg QID with prazosin 20 mg/d or placebo in 642 patients with mild to severe HF (New York Heart Association [NYHA] class II-III), those receiving ISDN and HYD had a 34% reduction in mortality risk compared with those receiving placebo (P < 0.038). In V HeFT II, which compared the same dosages of ISDN and HYD with enalapril 20 mg/d in 804 patients with NYHA class II-IV HF, those receiving enalapril had a 28% reduction in mortality risk compared with those receiving ISDN and HYD (P = 0.016). A predetermined subanalysis of VHeFT I and V-HeFT II found that black patients receiving ISDN and HYD had a 47% reduction in relative mortality risk compared with nonblack patients (hazard ratio = 0.53 vs 130, respectively; P = 0.04). In A-HeFT, which compared combination ISDN/HYD 40/75 mg TID with placebo in 1050 patients with moderate to severe HF (NYHA class III-IV), ISDN/HYD was associated with fewer deaths compared with placebo (32 vs 54, respectively; P = 0.02), a lower incidence of first hospitalizations for HF (85 vs 130; P = 0.002), and a larger number of patients with marked improvement (>10 units) in quality-of-life scores, as measured on the Minnesota Living with Heart Failure Questionnaire (180 vs 166; P = 0.01). In A-HeFT, adverse events occurring with a greater incidence in the ISDN/HYD group than the placebo group were headache (49.5% vs 21.1%, respectively), dizziness (30.1% vs 13.7%), nausea and vomiting (9.7% vs 6.1%), hypotension (7.9% vs 4.4%), sinus congestion (4.3% vs 1.7%), and tachycardia (4.1% vs 2.7%). A pharmacoeconomic analysis based on health care resource utilization in A-HeFT found the ISDN/HYD combination product to be cost-effective over a wide range of acquisition costs (up to 12 US dollars/d ).

CONCLUSIONS

The findings of these 3 large controlled clinical trials support the efficacy of ISDN and HYD in patients with HE Using a composite end point of mortality, HT hospitalization, and quality of life, the A-HeFT study found benefits to adding the fixed-dose ISDN/HYD combination product to standard therapy in self-identified black patients of African descent with moderate to severe HF.

Premature ovarian failure, endothelial dysfunction and estrogen-progestogen replacement

Cardiovascular disease, including coronary artery disease, stroke and peripheral vascular disease, is the leading cause of death among women. Vascular endothelial dysfunction is an early marker of atherosclerosis. Women with premature ovarian failure (or premature menopause) present an increased risk for cardiovascular disease, which might be attributed to the early onset of vascular endothelial dysfunction, associated with sex steroid deficiency. Cyclical estrogen and progestogen therapy has been shown to restore endothelial function in these young women. Further research is required to assess primarily the long-term effects of hormone replacement therapy on cardiovascular and overall prognosis in young women with premature ovarian failure, as well as the effects of different doses, duration and routes of hormone administration in these women.

Short-term improvement in submaximal exercise capacity by optimized therapy with ACE inhibitors and beta blockers in heart failure patients is associated with restoration of peripheral endothelial function

BACKGROUND

Improved exercise capacity in chronic heart failure (CHF) has been attributed to restoration of endothelial function. ACE inhibitors as well as beta blockers have previously been shown to enhance endothelial function and exercise capacity. The aim of this study was to determine whether short-term improvement in submaximal exercise capacity induced by optimized therapy with ACE inhibitors in combination with beta blockers is associated with restoration of endothelial function in CHF patients.

METHODS

Thirty-three patients with CHF were evaluated: six-minute walk test, NYHA class, brain natriuretic peptide (BNP), big Endothelin-1 (bigET-1) and flow-mediated vasodilation (FMD) of the brachial artery were assessed at baseline and after a 3-month period of optimized neurohormonal therapy. Two groups were formed retrospectively based on the changes in submaximal exercise capacity (responders and non-responders).

RESULTS

Optimization of neurohormonal therapy was comparable between groups. Responders (n=17) revealed a significant increase in walking distance (304+/-109 to 441+/-75 m; p<0.01), which was paralleled by a decrease in NYHA class (2.7+/-0.6 to 2.0+/-0.4; p<0.01), BNP (484+/-454 to 243+/-197 pg/ml; p<0.01), and bigET-1 (2.0+/-0.9 vs. 1.5+/-0.6 fmol/ml; p=0.04). By contrast, the latter variables did not change in non-responders. Improvement in functional capacity in responders was associated with an increase in FMD (8.2+/-3.9% to 11.0+/-5.6%; p<0.05). Increments in FMD were directly correlated with increases in walking distance (r=0.34; p<0.05).

CONCLUSION

Short-term improvement of submaximal exercise capacity in CHF patients following optimized therapy with ACE inhibitors and beta blockers is associated with restoration of endothelial function in conduit arteries.

Antithrombotic therapy for congestive heart failure

Patients with congestive heart failure (CHF) are at increased risk of thromboembolic events. However, there is much debate and uncertainty over the use of antithrombotic therapy in these patients. The evidence for oral anticoagulation is limited, although large randomised trial data are forthcoming. Aspirin may be detrimental for heart failure due to a possible interaction with angiotensin-converting enzyme inhibitors, leading to increased hospitalisations from decompensated heart failure. The objective of this review article is to summarise the available evidence regarding the risk of stroke and thromboembolic events in CHF patients, as well as the effectiveness and risks of antithrombotic therapy in these patients.

The clinical significance of endothelial dysfunction

PURPOSE OF REVIEW

Endothelial dysfunction is thought to play a pivotal role in the development, progression, and clinical complications of atherosclerosis. Several recent studies have addressed the clinical implications of endothelial dysfunction for cardiovascular events, atherosclerosis, restenosis, and heart failure. Novel findings with respect to endothelial progenitor cells and their alteration by cardiovascular risk factors are characterized and potential therapeutic interventions to improve endothelial and endothelial progenitor cell function are discussed.

RECENT FINDINGS

Over the past 5 years evidence has accumulated from clinical studies for a close association of the degree of endothelial dysfunction and clinical cardiovascular events in patients with cardiovascular risk factors, coronary disease, acute coronary syndrome, or heart failure. Understanding of the mechanisms leading to endothelial dysfunction has improved, including the notion that dysfunctional endothelial nitric oxide synthase, in part due to deficiency of the endothelial nitric oxide synthase cofactor tetrahydrobiopterin, likely plays an important role. Major progress has been made in understanding the role of endothelial progenitor cells, which likely contribute to both ischemia-induced neovascularization and endothelial regeneration after injury. Endothelial progenitor cell function is altered in patients with cardiovascular risk factors.

SUMMARY

Recent research on endothelial and endothelial progenitor cell dysfunction supports their clinical significance and has led to important insights in the pathophysiology of cardiovascular disease and at the same time provides an important opportunity to develop novel therapeutic approaches. Endothelial function represents a valuable surrogate endpoint to assess the impact of therapeutic interventions.

Systemic endothelial dysfunction as an early predictor of adverse outcome in heart failure

OBJECTIVE

Endothelial dysfunction is an early event in the natural progression of heart failure. Increased oxidative stress has been linked to impaired endothelial function and both may play a prognostic role.

METHODS AND RESULTS

Endothelium-dependent and endothelium-independent vasodilatation were determined in 289 patients with mild left ventricular dysfunction by measuring forearm blood flow responses to acetylcholine and sodium nitroprusside using venous occlusion plethysmography. Vascular effects of the coadministration of the antioxidant vitamin C at pharmacological doses (24 mg/min) were assessed. Occurrence of death, heart transplantation, and readmission with worsening heart failure were recorded as clinical outcome parameters during a follow-up period of 4.8 years. Patients experiencing adverse events (n=79) had lower vasodilator responses to acetylcholine (P<0.001) and to sodium nitroprusside (P=0.03) compared with patients without events. However, beneficial effects of vitamin C did not differ between both groups. Cox proportional hazards model demonstrated that age (P=0.001), renal function (P=0.001), and blunted acetylcholine-induced vasodilatation (P=0.007) remained independent predictors of adverse outcome.

CONCLUSIONS

Impaired peripheral endothelial function independently predicts long-term adverse outcome in patients with early-stage heart failure. The findings suggest that assessment of peripheral endothelial function may represent an additional mean for risk stratification and therapy management in these patients.