Prognostic implications of endothelial dysfunction: does it mean anything?

Erectile Dysfunction and Ischaemic Heart Disease

Erectile dysfunction (ED) is a common disorder that affects the quality of life of many patients. It is prevalent in more than half of males aged over 60 years. Increasing evidence suggests that ED is predominantly a vascular disorder. Endothelial dysfunction seems to be the common pathological process causing ED. Many common risk factors for atherosclerosis such as diabetes, hypertension, smoking, obesity and hyperlipidaemia are prevalent in patients with ED and so management of these common cardiovascular risk factors can potentially prevent ED. Phosphodiesterase type 5 inhibitors provide short-term change of haemodynamic factors to help initiate and maintain penile erection. They have been shown to be an effective and safe treatment strategy for ED in patients with heart disease, including those with ischaemic heart disease and hypertension.

Effect of short-term estrogen therapy on endothelial function: a double-blinded, randomized, controlled trial

OBJECTIVE

To evaluate the effect of short-term hormone replacement therapy with 0.625 mg conjugated estrogens daily on endothelial function of healthy postmenopausal women, using flow-mediated dilation (FMD) of the brachial artery.

METHODS

We performed a double-blinded, randomized, controlled trial over 3 years. Randomization was performed using computer-generated sorting. All participants were blinded to the use of conjugated equine estrogens (CEE) or placebo and FMD was assessed by a blinded examiner, before and after 28 days of medication. A total of 64 healthy postmenopausal women were selected and randomly assigned into two groups of treatment: 0.625 mg of CEE or placebo.

RESULTS

FMD values were statistically different between the groups (p = 0.025): the group receiving CEE showed a FMD value of 0.011 compared to the placebo group (FMD = -0.082). The two groups were additionally evaluated for homogeneity through the Shapiro-Wilk test in respect to variables that could interfere with endothelial function such as age (p = 0.729), body mass index (p = 0.891), and time since menopause (p = 0.724). Other variables were excluded during selection of the participants such as chronic vascular conditions, smoking, and sedentary lifestyle.

CONCLUSION

Our results demonstrate that the administration of 0.625 mg CEE for 28 days is effective in improving vascular nitric oxide-dependent dilation assessed by FMD of the brachial artery in postmenopausal women.

CLINICAL TRIAL REGISTRATION

NCT01482416.

Vascular effects of dietary salt

PURPOSE OF REVIEW

High dietary salt intake is detrimental in hypertensive and salt-sensitive individuals; however, there are a large number of normotensive salt-resistant individuals for whom dietary salt may also be harmful as a result of the blood pressure-independent effects of salt. This review will focus on the growing evidence that salt has adverse effects on the vasculature, independent of blood pressure.

RECENT FINDINGS

Data from both animal and human studies provide evidence that salt impairs endothelial function and increases arterial stiffness, independent of blood pressure. High dietary salt results in oxidative stress and increased endothelial cell stiffness, which impair endothelial function, whereas transforming growth factor beta promotes increased arterial stiffness in the presence of endothelial dysfunction.

SUMMARY

Health policies and most clinical research are focused on the adverse effects of dietary salt on blood pressure; however, there is an increasing body of evidence to support a deleterious effect of dietary salt on endothelial function and arterial stiffness independent of blood pressure. Endothelial dysfunction and increased arterial stiffness are predictors of cardiovascular disease; therefore, reducing excess dietary salt should be considered important for overall vascular health in addition to blood pressure.

Myocardial blood flow quantification for evaluation of coronary artery disease by positron emission tomography, cardiac magnetic resonance imaging, and computed tomography

The noninvasive detection of the presence and functional significance of coronary artery stenosis is important in the diagnosis, risk assessment, and management of patients with known or suspected coronary artery disease. Quantitative assessment of myocardial perfusion can provide an objective and reproducible estimate of myocardial ischemia and risk prediction. Positron emission tomography, cardiac magnetic resonance, and cardiac computed tomography perfusion are modalities capable of measuring myocardial blood flow and coronary flow reserve. In this review, we will discuss the technical aspects of quantitative myocardial perfusion imaging with positron emission tomography, cardiac magnetic resonance imaging, and computed tomography, and its emerging clinical applications.

High dietary sodium intake impairs endothelium-dependent dilation in healthy salt-resistant humans

BACKGROUND

Excess dietary sodium has been linked to the development of hypertension and other cardiovascular diseases. In humans, the effects of sodium consumption on endothelial function have not been separated from the effects on blood pressure. The present study was designed to determine if dietary sodium intake affected endothelium-dependent dilation (EDD) independently of changes in blood pressure.

METHOD

Fourteen healthy salt-resistant adults were studied (9M, 5F; age 33 ± 2.4 years) in a controlled feeding study. After a baseline run-in diet, participants were randomized to a 7-day high-sodium (300-350 mmol/day) and 7-day low-sodium (20 mmol/day) diet. Salt resistance, defined as a 5 mmHg or less change in a 24-h mean arterial pressure, was individually assessed while on the low-sodium and high-sodium diets and confirmed in the participants undergoing study (low-sodium: 85 ± 1 mmHg; high-sodium: 85 ± 2 mmHg). EDD was determined in each participant via brachial artery flow-mediated dilation on the last day of each diet.

RESULTS

Sodium excretion increased during the high-sodium diet (P < 0.01). EDD was reduced on the high-sodium diet (low: 10.3 ± 0.9%, high: 7.3 ± 0.7%; P < 0.05). The high-sodium diet significantly suppressed plasma renin activity (PRA), plasma angiotensin II, and aldosterone (P < 0.05).

CONCLUSION

These data demonstrate that excess salt intake in humans impairs endothelium-dependent dilation independently of changes in blood pressure.

Variability and reproducibility of flow-mediated dilatation in a multicentre clinical trial

AIMS

The aim of this study was to assess the reproducibility of flow-mediated dilatation (FMD) in a multicentre setting.

METHODS AND RESULTS

This study was performed as part of the dal-VESSEL trial in which FMD was measured in 19 vascular imaging centres in six European countries. A subgroup of patients who were allocated in the placebo group and scanned twice at each trial time point (substudy) was analysed. Intra-sonographer variability was calculated from FMD measurements 48 h apart. Centre variability and short-, medium-, and long-term reproducibility of FMD were calculated at 48 h and at 3 and 9 months intervals, respectively. Intra- and inter-reader variability was assessed by re-analysing the FMD images by three certified readers at two time intervals, 7 days apart. Sixty-seven patients were included. Variability between centres was comparable at 48 h and 3 months interval but almost doubled at 9 months. The mean absolute difference in %FMD was 1.04, 0.99, and 1.45% at the three time intervals, respectively. Curves were generated to indicate the number of patients required for adequate power in crossover and parallel study designs.

CONCLUSION

This study demonstrates for the first time that in a multicentre setting reproducible FMD measurements can be achieved for short- and medium-term evaluation, which are comparable with those reported from specialized laboratories. These findings justify the use of FMD as an outcome measure for short- and medium-term assessment of pharmacological interventions.

Risk evaluation for coronary artery disease in patients with impaired glucose tolerance after a successful coronary intervention

PURPOSE

Patients with coronary artery disease (CAD) often have risk factors that may influence endothelial function. The purpose of this study was to evaluate the endothelial function and its association with coronary risk factors after percutaneous coronary intervention (PCI).

MATERIALS AND METHODS

A total of 14 patients with impaired glucose tolerance and CAD underwent positron emission tomography with N-13 ammonia to measure myocardial blood flow (MBF) at rest and during a cold pressor test (CPT), to estimate endothelial function as a percent increase (%increase) of MBF. The results were compared among normal segments (normal), reperfused segments with PCI (PCI), and nonculprit CAD segments without PCI (non-PCI). Correlations between the %increase and major risk factors were also investigated.

RESULTS

CPT induced significant increase in MBF in all groups. The %increase of normal, non-PCI, and PCI groups were 33% ± 22%, 21% ± 23%, and 26% ± 23%, respectively. Comparison with risk factors demonstrated significant correlations only in the non-PCI group. Specifically, there were negative correlations between %increase and fasting blood sugar (r = -0.64, P < 0.05), hemoglobin A1c (r = -0.74, P < 0.05), total cholesterol (r = -0.87, P < 0.05), triglyceride (r = -0.71, P < 0.05), and low-density lipoprotein cholesterol (r = -0.92, P < 0.005), respectively.

CONCLUSIONS

Although impaired glucose tolerance patients with a PCI-treated coronary stenosis showed preserved response to CPT, the %increase negatively correlated with risk factors in the non-PCI segments. Therefore, coronary risk factors may affect CAD lesions in PCI-treated patients.

Parathyroid Hormone's Acute Effect on Vasodilatory Function

Parathyroid hormone (PTH) seems to affect the risk of cardiovascular disease. The aim of the present study was to investigate PTH's acute effect on endothelial vasodilatory function in forearm resistance vessels. Ten healthy subjects underwent forearm venous occlusion plethysmography. We measured forearm blood flow at baseline and at a stable, locally increased PTH level after intra-arterial infusion of metacholine and nitroprusside. The contralateral arm served as a control. Ionized calcium (Ca++) and PTH values were normal in all subjects at baseline (1.26 ± 0.02 mM/L, 3.6 ± 1.2 pM/L). After 30 minutes of PTH infusion, the PTH level increased in the active arm (13.8 ± 4.0 pM/L P < 0.01), while the Ca++ level was unchanged (1.25 ± 0.04; mM/L). Both the PTH and the Ca++ level in the contralateral arm remained unchanged, which indicates no systemic influence. The endothelial-dependent vasodilation was inversely correlated to the Ca++ level at baseline (r = -0.75, P < 0.05) and after PTH infusion (r = -0.68, P < 0.05). The vasodilatory function was not affected during PTH-infusion.

PET/CT challenge for the non-invasive diagnosis of coronary artery disease

This review will focus on the clinical potential of PET/CT for the characterization of cardiovascular diseases. We describe the technical challenges of combining instrumentation with very different imaging performance and discuss the clinical applications in the field of cardiology.

The association between glycemia and endothelial function in nondiabetic individuals: the importance of body weight

The aim of this study was to examine the association between glycemia and markers of early atherosclerosis in healthy nondiabetic individuals. In 309 individuals without diabetes or symptomatic cardiovascular disease, we assessed long-term glycemia by glycosylated hemoglobin (HbA1c) and endothelial function by flow-mediated dilatation (FMD) in the brachial artery. HbA1c was negatively associated with FMD (r = -0.162, P = 0.004). Multivariate linear regression analysis after adjusting for common risk factors of cardiovascular disease showed that BMI was an effect modifier of the association between HbA1c and FMD (P = 0.034 for the HbA1c x BMI interaction). We stratified the FMD outcome data into two groups separated by the median BMI (group 1: BMI < or = 26.1 kg/m(2) and group 2: BMI > 26.1 kg/m(2)). In the lower BMI group, HbA1c was an independent predictor of FMD even when adjusted for confounding factors associated with impaired glucose metabolism (r = -0.215, P = 0.009), but in the higher BMI group HbA1c was not associated with FMD (r = -0.051, P = 0.5). In a nondiabetic population, long-term glycemia was associated with endothelial dysfunction only in lean individuals. In the overweight individuals, this association was not apparent, possibly because some of the mechanisms that mediate the effect of glycemia on vascular function are shared by obesity.

[Microcirculation in diabetes: implications for chronic complications and treatment of the disease]

Diabetic microangiopathy is responsible for an important rate of morbidity and mortality related to the disease. Endothelial damage seems to be the triggering factor in the pathogenesis of microvascular complications. Diabetes mellitus and other metabolic diseases are associated to endothelial dysfunction, the most precocious known marker of atherosclerosis. Changes on microvascular reactivity are present in patients with diabetes mellitus, as well as in individuals with risk factors for this disease. Evaluation of endothelial and microvascular functions is possible using different invasive or preferentially non-invasive methods. Adequate control of diabetes mellitus might postpone or perhaps even prevent the microvascular disease. Microvascular dysfunction, when seen only by changes on microvascular reactivity, could be ameliorated with correction of risk factors or drug treatment.

Time since menopause influences the acute and chronic effect of estrogens on endothelial function

OBJECTIVE

We evaluated whether time since menopause influences the acute and chronic effect of Estradiol (E) on vascular endothelial function.

METHODS AND RESULTS

We studied flow-mediated dilatation (FMD) in 134 postmenopausal women (PMW) before and after acute and chronic E administration. At baseline FMD was inversely associated to time from menopause (r=-0.67, P<0.001) and age (r=-0.43, P<0.05), in exogenous estrogen naïve but not in previous users. Acute and chronic E improved endothelial function in all women. E administration improved FMD more in women within 5 years since menopause than in those with more than 5 years since menopause (76% and 74% versus 45% and 48%, acute and chronic E, respectively; P<0.05). Among women with more than 5 years since menopause acute and chronic E increased FMD more in previous E users than in nonusers (59% and 63% versus 31% and 38%, acute and chronic E, respectively; P<0.01). Multivariate analysis showed that time from menopause was a predictor of impaired FMD and of its improvement after acute and chronic E.

CONCLUSIONS

Time from menopause influences FMD in PMW. The acute and chronic effect of E on FMD is time dependent and is reduced by a longer time since menopause.

Diagnostic value of PET-measured heterogeneity in myocardial blood flows during cold pressor testing for the identification of coronary vasomotor dysfunction

BACKGROUND

We aimed to evaluate the diagnostic value of a positron emission tomography (PET)-measured heterogeneity in longitudinal myocardial blood flow (MBF) during cold pressor testing (CPT) and global MBF response to CPT from rest (DeltaMBF) for identification of coronary vasomotor dysfunction.

METHODS AND RESULTS

In 35 patients CPT-induced alterations in epicardial luminal area were determined with quantitative angiography as the reference. MBF was assessed over the whole left ventricle as global MBF and regionally in the mid and mid-distal myocardium as MBF difference or MBF heterogeneity with nitrogen-13 ammonia and PET. The sensitivity and specificity of a longitudinal MBF difference during CPT in the identification of epicardial vasomotor dysfunction were significantly higher than the global DeltaMBF to CPT (88% vs 79% and 82% vs 64%, respectively; P < .05). Combining both parameters resulted in an optimal sensitivity of 100% at the expense of an intermediate specificity of 73%. The diagnostic accuracy was higher for the combined analysis than that for the MBF difference alone and global DeltaMBF alone (91% vs 86% and 74%, respectively; P < .05).

CONCLUSIONS

The combined evaluation of a CPT-induced heterogeneity in longitudinal MBF and the change in global MBF from rest may emerge as a new promising analytic approach to further optimize the identification and characterization of coronary vasomotor dysfunction.

O endotélio na síndrome metabólica

O endotélio é responsável pela manutenção da homeostase vascular. Em condições fisiológicas, mantém o tônus vascular, o fluxo sangüíneo laminar, a fluidez da membrana plasmática, o equilíbrio entre coagulação e fibrinólise, a inibição da proliferação e da migração celulares e o controle da resposta inflamatória. A disfunção endotelial é definida como uma alteração do relaxamento vascular por diminuição da biodisponibilidade de fatores de relaxamento derivados do endotélio, principalmente o óxido nítrico (NO). Estas respostas vasomotoras anormais ocorrem na presença de inúmeros fatores de risco para a aterosclerose. A síndrome metabólica é considerada um estado de inflamação crônica que se acompanha de disfunção endotelial e ocasiona aumento na incidência de eventos isquêmicos cardiovasculares e elevada mortalidade. Essa revisão abordará o processo fisiológico de regulação da função vascular pelo endotélio, os métodos disponíveis para avaliação in vivo da disfunção endotelial e as terapias capazes de melhorar a função vascular e conseqüentemente minimizar o risco cardiovascular dessa síndrome tão prevalente no nosso meio.

Plasma markers of endothelial dysfunction in type 2 diabetics

BACKGROUND

Type 2 diabetes, or non-insulin-dependent diabetes mellitus, represents an independent risk factor for cardiovascular diseases (CVD), being characterized by a continuous low-grade inflammation and endothelial activation state. Atherosclerotic lesions occur in diabetic patients at an earlier age with severe clinical manifestations and poor outcome. Our objective was to investigate the correlation between lipoprotein-associated phospholipase A2 (PLA2-LDL), myeloperoxidase (MPO), and paraoxonase (PON), enzymes implicated in the evolution of endothelial dysfunction associated with type 2 diabetes.

METHODS

One hundred diabetic patients [50 without documented coronary artery disease (group 1) and 50 with CVD (group 2)] and 46 healthy controls were investigated for PLA2-LDL, MPO, and PON activities.

RESULTS

PLA2-LDL activity was significantly higher in group 2 than in group 1 and among controls. PON activity was lower in group 1 than in controls, reaching the lowest level in group 2. MPO activity was higher in type 2 diabetics than among controls, with similar values in groups 1 and 2.

CONCLUSIONS

The evaluation of PLA2-LDL, MPO, and PON activities may improve early diagnosis of CVD in asymptomatic patients with type 2 diabetes and can help to evaluate accelerated atherosclerosis and microvascular disease.

Linking erectile dysfunction and coronary artery disease

Coronary artery disease (CAD) and erectile dysfunction (ED) are both highly prevalent conditions that frequently coexist. Additionally, they share mutual vascular risk factors, suggesting that they are both manifestations of systemic vascular disease. The role of endothelial dysfunction in CAD is well established. Normal erectile function is primarily a vascular event that relies heavily on endothelially derived, nitric oxide-induced vasodilation. Accordingly, endothelial dysfunction appears to be a common pathological etiology and mechanism of disease progression between CAD and ED. The risk factors of diabetes mellitus, hypertension, hyperlipidemia, obesity and tobacco abuse contribute to endothelial dysfunction. This article reviews the role of vascular endothelium in health, the abnormalities resulting from vascular risk factors, and clinical trials evaluating the role of endothelial dysfunction in ED.

Endothelial dysfunction occurs in peripheral circulation patients with acute and stable coronary artery disease

Atherosclerosis is a diffuse, systemic process. In addition, acute coronary syndromes (ACS) are associated with inflammatory marker elevations that are hypothesized to affect the function of nonculprit coronary as well as peripheral vessels. We investigated whether femoral vascular reactivity and/or fibrinolytic capacity are impaired in ACS patients over and above any dysfunction associated with stable coronary artery disease. Patients undergoing diagnostic coronary angiography (n = 42 total, 14 patients/group) were recruited into three groups as follows: 1) stable coronary syndromes (SAP group), 2) ACS as defined by rest angina with ECG changes and troponin rise (ACS group), and 3) angiographically normal coronary arteries (control group). After diagnostic coronary angiography, femoral artery endothelial and smooth muscle function were assessed by infusing acetylcholine (ACh) and nitroglycerin (GTN), and tissue-type plasminogen activator (t-PA) release across the femoral circulation was measured as the difference between arterial and venous concentrations before and after ACh and GTN stimulation. There were no significant differences between groups in relevant baseline characteristics apart from significantly higher C-reactive protein levels and reduced net t-PA release in the ACS group at baseline (P < 0.05). The ACS and SAP groups had equivalent angiographic severity of coronary artery disease. Endothelium-dependent dilatation was significantly higher in control individuals (14.9 +/- 9.1%; P < 0.001) compared with either stable patients (2.3 +/- 8.1%) or those with unstable syndromes (2.6 +/- 8.9%, who were similar to each other; P = not significant). Although baseline t-PA release was impaired in the ACS patients (0.09 +/- 0.06 compared with 0.39 +/- 0.33 and 0.49 +/- 0.56 ng/ml; P = 0.03), stimulation of t-PA release by ACh and GTN occurred only in the control subjects and not in the ACS or SAP patients. Coronary artery disease is associated with impaired endothelium-dependent dilatation and impaired stimulation of t-PA release in the systemic circulation. These aspects of endothelial dysfunction, however, were equally severe in acute and chronic coronary syndrome patients.

Rapid Effects of Rosiglitazone Treatment on Endothelial Function and Inflammatory Biomarkers

Background— Antidiabetic thiazolidinediones (TZDs), like rosiglitazone or pioglitazone, improve endothelial function in patients with type 2 diabetes or metabolic syndrome, but it is currently unknown, whether these beneficial effects of TZDs depend on their metabolic action or may be caused by direct effects on the endothelium. Therefore, the present study examined whether short-term rosiglitazone treatment influences endothelium-dependent vasodilation as well as serum levels of vascular disease biomarkers in healthy, nondiabetic subjects.

Methods and Results— Short-term treatment (21 days) of healthy subjects (n=10) did not significantly change blood glucose levels or lipid profile. In contrast, rosiglitazone significantly increased flow-mediated, endothelium-dependent vasodilation already within the first day from 5.3±2.7% at baseline to 7.8±2.6%, further increasing it to 9.4±3.0% at day 21. In addition, the early improvement of endothelium-dependent vasodilation was paralleled by a rapid reduction of serum levels of the biomarkers C-reactive protein (CRP), serum amyloid A (SAA), and sE-selectin. Moreover, after drug withdrawal all markers remained suppressed for the whole follow-up period of 7 days. In contrast, rosiglitazone treatment did not significantly affect tumor necrosis factor (TNF)-α, interleukin (IL)-6, sICAM-1, sVCAM-1, and sCD40L levels.

Conclusions— Our study suggests a direct effect of TZD treatment on endothelial function and inflammatory biomarkers of arteriosclerosis, promoting the concept that TZDs, independent of their metabolic action, may exhibit protective effects in the vessel wall.

Insulin resistance and the endothelium

There is increasing evidence of a parallel progression between insulin resistance and endothelial dysfunction, suggesting a close association between insulin action and the endothelium. Numerous studies have demonstrated that endothelial dysfunction occurs early in the insulin-resistant state and is predictive of future cardiovascular events. Similarly, insulin resistance has been associated with the metabolic syndrome, which also increases the risk of adverse cardiovascular outcomes. Approaches that improve endothelial dysfunction, such as treatment with statins, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or peroxisome proliferator-activated receptor gamma ligands, have been shown to prevent both diabetes and cardiovascular disease. This article reviews the relation between endothelial dysfunction and cardiovascular disease, assesses the endothelium in the spectrum of insulin resistance, and examines the effect of the thiazolidinediones on endothelial function.

Effect of plasminogen activator inhibitor-1 in diabetes mellitus and cardiovascular disease

Concentrations of plasminogen activator inhibitor-1 (PAI-1) are elevated beginning at the stage of impaired glucose tolerance and continuing through the development of diabetes mellitus and the metabolic syndrome. Evolving evidence of the central role of PAI-1 in mediating fibrosis and thrombosis increasingly supports the theory that it is a significant risk factor for macrovascular complications and cardiovascular disease, particularly in patients with diabetes. Several clinical studies have demonstrated a strong correlation between circulating PAI-1 levels and cardiovascular events and mortality. With the potentially severe effects of elevated PAI-1 levels becoming evident, there is increased interest in developing therapies targeted at reducing PAI-1 expression or circulating concentrations. Thus far, weight loss, inhibitors of the renin-angiotensin system, and insulin sensitization through use of thiazolidinediones (TZDs) appear to be the most promising strategies for managing elevated PAI-1 levels. Of these, TZD therapy is the only one that provides the benefits of both long-term glycemic control and improved cardiovascular risk profile. This article reviews the regulation of PAI-1, its activity in various disease states, and available treatment options.

Evaluation of a novel sutureless anastomotic connector: From endothelial function to mid-term clinical and angiographic follow-up

OBJECTIVES

We evaluated the effect of the St Jude Medical sutureless anastomotic connector on endothelium-dependent and -independent saphenous vein graft relaxation, as well as on clinical outcomes and graft patency in patients.

METHODS

Human saphenous vein grafts were assigned to control or connector groups (loaded for 1 or 5 minutes; n = 18). Isometric dose-response curves to endothelium-dependent and -independent (sodium nitroprusside) vasodilators were constructed in saphenous vein grafts precontracted with phenylephrine. Thrombin-mediated vasorelaxation, an early determinant of saphenous vein graft failure, was also evaluated. Percent maximum relaxation was compared between groups. Patients in whom the St Jude Medical connector was employed underwent clinical follow-up, stress tests, and angiography 6 to 12 months postoperatively.

RESULTS

A23187-induced endothelium-mediated relaxation, sodium nitroprusside-induced endothelium-independent relaxation, and thrombin-mediated vasorelaxation did not differ between control and connector saphenous vein grafts at either time point studied. Twenty-seven patients received St Jude Medical connectors. There was no hospital mortality; patients were followed for 679 +/- 241 days. There was 1 late death; the connector saphenous vein graft was patent at postmortem. All connector saphenous vein grafts were patent at follow-up angiography. Four grafts had stenoses (30%-60%), without symptoms or requirement for intervention. All hand-sewn saphenous vein grafts were also patent.

CONCLUSIONS

The St Jude Medical connector does not impair endothelium-dependent vasorelaxation. In patients, patency of the connector saphenous vein grafts 6 to 12 months postoperatively was 100% but 22% of grafts had non-flow-limiting stenoses at or near the connector. Further long-term studies are required to confirm the safety of the St Jude Medical connector with regards to endothelial function and restenosis.

Coronary endothelial dysfunction is associated with an increased risk of cerebrovascular events

BACKGROUND

Stroke, mainly attributable to atherothrombotic disease, represents a leading cause of disability and death in the Western world. Endothelial dysfunction, which is considered a key factor in atherogenesis, is associated with an increased risk of cardiovascular events. However, the magnitude of the association between coronary endothelial dysfunction (CED) and cerebrovascular events is unknown. This study was performed to investigate the association between CED and cerebrovascular events.

METHODS AND RESULTS

We studied 503 patients without obstructive coronary artery disease (CAD) who underwent coronary endothelial function testing by intracoronary acetylcholine infusion. Patients were divided according to the presence (n=305) or absence (n=198) of CED, and medical records were examined for the occurrence of ischemic or hemorrhagic stroke or transient ischemic attack either before (prevalent) or after (incident) coronary endothelial function testing. Among the study population, a total of 25 cerebrovascular events were documented, 22 in patients with CED (15 prevalent) and 3 in patients without (all prevalent) (P=0.008). Multivariable logistic regression, which included traditional cerebrovascular disease-related risk factors, identified the presence of CED as the single strongest factor associated with cerebrovascular events (OR, 4.32; 95% CI, 1.26 to 14.83). Kaplan-Meier analysis indicated that patients with CED had a significantly higher cumulative cerebrovascular event rate than those without (P=0.04).

CONCLUSIONS

Presence of CED in patients without obstructive CAD is independently associated with an increased risk of cerebrovascular events. Thus, detection of this early stage of atherosclerosis may provide important information to identify patients who benefit from aggressive preventive strategies.

Calcium antagonist treatment by lercanidipine prevents hyperpolarization in essential hypertension

Essential hypertension is associated with impaired endothelium-dependent vasodilation caused by oxidative stress-induced nitric oxide (NO) breakdown and compensatory production of a hyperpolarizing factor. To test whether calcium antagonist treatment can restore NO availability and prevent hyperpolarization through antioxidant properties, in 15 healthy subjects and 15 patients with essential hypertension, we studied forearm blood flow (strain-gauge plethysmography) modifications induced by intrabrachial bradykinin (5, 15, 50 ng/100 mL per minute), an endothelium-dependent vasodilator, in basal conditions, during infusion of NG-monomethyl-l-arginine (L-NMMA, 100 microg/100 mL per minute), an NO-synthase inhibitor, and ouabain (0.72 microg/100 mL per minute), an Na+-K+ ATPase inhibitor to prevent hyperpolarization. These infusions were repeated in the presence of the antioxidant vitamin C (8 mg/100 mL/min). The response to sodium nitroprusside was also evaluated. In controls, vasodilation to bradykinin was inhibited by L-NMMA and remained unchanged by ouabain or vitamin C. In hypertensive patients, vasodilation to bradykinin was blunted and resistant to L-NMMA but sensitive to ouabain. Vitamin C increased the response to bradykinin and restored the inhibiting effect of L-NMMA while preventing the effect of ouabain. In hypertensive patients, infusions were repeated after 3-month treatment with lercanidipine (10 to 20 mg daily). Lercanidipine decreased plasma lipoperoxides, isoprostanes, and malondialdehyde and increased plasma antioxidant capacity. Moreover, lercanidipine increased the vasodilation to bradykinin and restored the inhibiting effect of L-NMMA on bradykinin-induced vasodilation while preventing the effect of ouabain. Finally, vitamin C no longer exerted its facilitating activity. These results indicate that in essential hypertension, lercanidipine increases endothelium-dependent vasodilation by restoring NO availability and preventing hyperpolarization, an effect probably determined by antioxidant activity.

Mechanisms underlying the programming of small artery dysfunction: review of the model using low protein diet in pregnancy in the rat

Human and animal studies have shown that unbalanced maternal nutrition is associated with the development of cardiovascular and metabolic disease in adulthood. In the Southampton maternal low protein model (SMLP), protein deprivation (50%) throughout pregnancy in rats leads to elevated blood pressure in adult offspring. Impaired peripheral arterial function may contribute to the cardiovascular dysfunction observed in these offspring. This review discusses the impact of such a dietary insult on the vascular function of resistance arteries from pregnant rats (pF(o)), their offspring (F(1)), the pregnant offspring (pF(1)) and the second generation (F(2)). At each stage, disturbances in endothelium-dependent relaxation were observed, implicating changes in endothelial nitric oxide (NO)-guanylate cyclase (GC) signalling pathway in the vascular adaptations to pregnancy and the programmed effects on offspring.

Prevention of myocardial infarction

Despite the rapid advances that have been made in the treatment of coronary artery disease, myocardial infarction remains the major cause of death in the developed world and a growing problem for developing countries. To address this growing problem, a strategy aimed at prevention of events in high-risk individuals is required. This involves assessment of cardiovascular risk followed by risk reduction. At present there is no perfect technique available for risk prediction, although computed tomography and magnetic resonance imaging scanning, along with serum markers of inflammation, offer the greatest potential. The applicability of these techniques at present is also limited by cost and accessibility. Risk reduction is possible through lifestyle changes and drug therapy, and effective risk assessment is essential in selecting those most likely to benefit from these interventions.