Relations between cardiac and vascular structure in patients with primary and secondary hypertension

Microcirculation in Hypertension: A Therapeutic Target to Prevent Cardiovascular Disease?

Arterial hypertension is a common condition worldwide and an important risk factor for cardio- and cerebrovascular events, renal diseases, as well as microvascular eye diseases. Established hypertension leads to the chronic vasoconstriction of small arteries as well as to a decreased lumen diameter and the thickening of the arterial media or wall with a consequent increased media-to-lumen ratio (MLR) or wall-to-lumen ratio (WLR). This process, defined as vascular remodeling, was firstly demonstrated in small resistance arteries isolated from subcutaneous biopsies and measured by micromyography, and this is still considered the gold-standard method for the assessment of structural alterations in small resistance arteries; however, microvascular remodeling seems to represent a generalized phenomenon. An increased MLR may impair the organ flow reserve, playing a crucial role in the maintenance and, probably, also in the progressive worsening of hypertensive disease, as well as in the development of hypertension-mediated organ damage and related cardiovascular events, thus possessing a relevant prognostic relevance. New non-invasive techniques, such as scanning laser Doppler flowmetry or adaptive optics, are presently under development, focusing mainly on the evaluation of WLR in retinal arterioles; recently, also retinal microvascular WLR was demonstrated to have a prognostic impact in terms of cardio- and cerebrovascular events. A rarefaction of the capillary network has also been reported in hypertension, which may contribute to flow reduction in and impairment of oxygen delivery to different tissues. These microvascular alterations seem to represent an early step in hypertension-mediated organ damage since they might contribute to microvascular angina, stroke, and renal dysfunction. In addition, they can be markers useful in monitoring the beneficial effects of antihypertensive treatment. Additionally, conductance arteries may be affected by a remodeling process in hypertension, and an interrelationship is present in the structural changes in small and large conductance arteries. The review addresses the possible relations between structural microvascular alterations and hypertension-mediated organ damage, and their potential improvement with antihypertensive treatment.

State of the Art Review: Vascular Remodeling in Hypertension

Although the gold-standard method for the assessment of structural alteration in small resistance arteries is the evaluation of the MLR by micromyography in bioptic tissues, new, noninvasive techniques are presently under development, focusing mainly on the evaluation of WLR in retinal arterioles. These approaches represent a promising and interesting future perspective. Appropriate antihypertensive treatment is able to prevent the development of microvascular alterations or to induce their regression. Also, conductance arteries may be affected by a remodeling process in hypertension, and a cross-talk may exist between structural changes in the small and large arteries. In conclusion, the evaluation of microvascular structure is ready for clinical prime time, and it could, in the future, represent an evaluation to be performed in the majority of hypertensive patients, to better stratify cardiovascular risk and better evaluate the effects of antihypertensive therapy. However, for this purpose, we need a clear demonstration of the prognostic relevance of noninvasive measures of microvascular structure, in basal conditions and during treatment. Vascular remodeling may be frequently observed in hypertension, as well as in obesity and diabetes mellitus. An increased media to lumen ratio (MLR) or wall to lumen ratio (WLR) in microvessels is the hallmark of hypertension, and may impair organ flow reserve, being relevant in the maintenance and, probably, also in the progressive worsening of hypertensive disease, as well as in the development of hypertension-mediated organ damage/cardiovascular events. The molecular mechanisms underlying the development of vascular remodeling are only partly understood.

Retinal arterial remodeling in patients with pheochromocytoma or paraganglioma and its reversibility following surgical treatment

OBJECTIVE

Structural abnormalities in resistance arteries are a hallmark of patients with hypertension. In hypertensive patients with pheochromocytoma or paraganglioma (PPGL), it is still a matter of debate whether structural vascular changes are because of elevated blood pressure (BP) or to toxic effects of elevated circulating catecholamines. Hence, the aim of our study was to assess whether catecholamine excess and/or elevated BP affect the structure of small retinal arteries in patients with catecholamine-producing tumors.

METHODS

The study included 27 patients with PPGL and 27 hypertensive patients. All patients underwent biochemical tests for catecholamine excess, echocardiography and analyses of scanning-laser-Doppler-flowmetry (SLDF) both at baseline and 12 months following surgical resection of PPGL.

RESULTS

Baseline retinal arterial diameter, arterial wall thickness and wall cross sectional area (WCSA) were higher in patients with PPGL as compared with subjects without PPGL (arterial diameter: 110 ± 16.5 vs. 99.5 ± 10.8 μm, wall thickness: 16.3 ± 6.0 vs. 13.5 ± 4.0 μm, WCSA: 4953.9 ± 2472.8 vs. 3784.1 ± 1446.3 μm, P < 0.05). Significant correlations were noted between wall thickness and WCSA and echocardiographic parameters assessing diastolic and systolic function of left ventricle. No correlations between retinal parameters, BP level and plasma concentrations of metanephrines were observed. In patients with PPGL, there were postoperative decreases in wall thickness (16.4 ± 15.8 vs. 14.8 ± 4.7 μm; P = 0.011) and WLR (0.42 ± 0.13 vs. 0.37 ± 0.10; P = 0.003) at 12 months after surgical removal of tumors.

CONCLUSION

This is the first study to demonstrate that catecholamine excess is related to thickening of retinal arteries independent of BP and reversible after surgical cure. These data support a role of catecholamines in vascular remodeling in PPGL patients.

Myocardial mechano-energetic efficiency in primary aldosteronism

BACKGROUND

Available data indicate that patients with primary aldosteronism have an increased risk of cardiovascular events and cardiovascular risk seems to be, at least in part, independent of blood pressure (BP) values. Patients with primary aldosteronism have a greater prevalence of left ventricular (LV) hypertrophy and subtle alterations of ventricular function, which might contribute to the increase in cardiovascular risk. Recently, a noninvasive approach for the estimation of LV mechanical efficiency, obtained by echocardiography has been proposed.

AIM OF THE STUDY

To evaluate the determinants of myocardial mechanoenergetic efficiency index (MEEi), in a large group of patients with primary aldosteronism (n = 99) and in a control group of essential hypertensive patients (n = 99) matched for age, sex and BP values.

RESULTS

No differences between groups for age, sex, BMI, BP values, glucose, lipid profile and renal function were observed. LV mass index was greater in primary aldosteronism vs. essential hypertensive patients (46.0 ± 16.7 vs. 36.9 ± 8.6 g/m2, P < 0.001); also relative wall thickness was greater in primary aldosteronism (0.36 ± 0.1 vs. 0.32 ± 0.4, P < 0.001). Left atrial dimensions were significantly greater in primary aldosteronism. Ejection fraction was not different between groups, while endocardial and midwall fractional shortening were lower in primary aldosteronism vs. essential hypertensive patients (40 ± 7 vs. 43 ± 6, and 18 ± 3 vs. 21 ± 2, both P < 0.01). MEEi was lower in primary aldosteronism vs. essential hypertensive patients (0.44 ± 0.14 vs. 0.52 ± 0.10 ml/s per g, P < 0.01). A negative correlation was observed between MEEi and aldosterone levels (r = -0.203, P < 0.05) and aldosterone : renin ratio (P = -0.172, P < 0.05); the correlation remained significant after adjustment for possible confounders.

CONCLUSION

In patients with primary aldosteronism myocardial MEEi is lower as compared with essential hypertensive patients. A reduced MEEi may reflect an impairment of production and utilization of energy in the myocardium, which could lead to the occurrence of cardiovascular complications and therefore these findings may contribute to explain the increased risk of cardiovascular events in patients with primary aldosteronism.

The importance of endothelial dysfunction in resistance artery remodelling and cardiovascular risk

AIMS

The relationship between resistance artery remodelling and endothelial function remains unknown. In this study, we assessed (i) the capacity of endothelial function and nitric oxide (NO) availability to provide more information on the severity of resistance artery remodelling than common cardiovascular risk factors in subjects at low or high cardiovascular risk; and (ii) differences between patterns of resistance artery remodelling associated with deficit of NO availability and with exposure to cardiovascular risk factors.

METHODS AND RESULTS

All analyses were conducted on the microvascular data set of the Italian Society for Arterial Hypertension (SIIA) that includes 356 patients with measures of small resistance arteries remodelling acquired with pressure or wire myography. Information on endothelial function and NO availability were also available in 116 patients. The European Heart Score (HS) was used to define the total cardiovascular risk of each patient. Endothelial function was inversely related with the severity of the resistance artery remodelling, and this association remained significant after adjustment for the HS. By contrast, the HS lost its significant association with the media-to-lumen (M/L) ratio and the media cross-sectional area after adjustment for endothelial function. The strength of these associations was similar in subjects at high and low cardiovascular risk. The addition of endothelial function and NO availability to the HS significantly improved the identification of subjects at more and less severe resistance artery remodelling. A severe deficit of NO availability was associated with hypertrophic remodelling, while a higher HS was more clearly associated with eutrophic remodelling.

CONCLUSION

Resistance artery endothelial function and NO availability might represent important factors involved in resistance artery remodelling, independently from cardiovascular risk factor exposure.

Association between blood pressure variability, cardiovascular disease and mortality in type 2 diabetes: A systematic review and meta-analysis

AIM

To investigate the associations of blood pressure variability (BPV), expressed as long-term (visit-to-visit) and short-term (ambulatory blood pressure monitoring [ABPM] and home blood pressure monitoring [HBPM]) and all-cause mortality, major adverse cardiovascular events (MACEs), extended MACEs, microvascular complications (MiCs) and hypertension-mediated organ damage (HMOD) in adult patients with type 2 diabetes.

MATERIALS AND METHODS

PubMed, Medline, Embase, Cinahl, Web of Science, ClinicalTrials.gov and grey literature databases were searched for studies including patients with type 2 diabetes, at least one variable of BPV (visit-to-visit, HBPM, ABPM) and evaluation of the incidence of at least one of the following outcomes: all-cause mortality, MACEs, extended MACEs and/or MiCs and/or HMOD. The extracted information was analyzed using random effects meta-analysis and meta-regression.

RESULTS

Data from a total of 377 305 patients were analyzed. Systolic blood pressure (SBP) variability was associated with a significantly increased risk of all-cause mortality (HR 1.12, 95% CI 1.04-1.21), MACEs (HR 1.01, 95% CI 1.04-1.17), extended MACEs (HR 1.07, 95% CI 1.03-1.11) and MiCs (HR 1. 12, 95% CI 1.01-1.24), while diastolic blood pressure was not. Associations were mainly driven from studies on long-term SBP variability. Qualitative analysis showed that BPV was associated with the presence of HMOD expressed as carotid intima-media thickness, pulse wave velocity and left ventricular hypertrophy. Results were independent of mean blood pressure, glycaemic control and serum creatinine levels.

CONCLUSIONS

Our results suggest that BPV might provide additional information rather than mean blood pressure on the risk of cardiovascular disease in patients with type 2 diabetes.

Hypertension with primary aldosteronism is associated with increased carotid intima-media thickness and endothelial dysfunction

Patients with primary aldosteronism induced hypertension are more likely to experience cardiovascular events compared to patients with essential hypertension. Primary aldosteronism may therefore have distinct adverse effects on cardiovascular structure and function, independent of hypertension. However, current data on such effects of primary aldosteronism are conflicting. The aim of the present study was to investigate the influence of primary aldosteronism on vascular structure and endothelial function, using intima‐media thickness as a vascular remodeling index and flow‐mediated dilation as a functional parameter. In total, 70 participants were recruited from patients with resistant hypertension. Twenty‐nine patients diagnosed with primary aldosteronism and 41 patients with essential hypertension were prospectively enrolled. Primary aldosteronism was due to aldosterone‐producing adenoma in 10 cases and due to idiopathic adrenal hyperplasia in 19 cases. All patients underwent ultrasound of the common carotid intima‐media thickness and flow‐mediated dilation of the brachial artery. Primary aldosteronism patients had significantly lower flow‐mediated dilation (3.3 [2.4‐7.4] % vs 14.7 [10.3‐19.9] %, P < 0.01) and significantly higher carotid intima‐media thickness (0.9 [0.7‐1.0] mm vs 0.8 [0.6‐0.9] mm, P = 0.02) compared to patients with essential hypertension. These differences remained significant after adjusting for age, sex, diabetes mellitus, 24‐hours systolic blood pressure, and smoking (P < 0.01). No differences in either outcome were observed between the adenoma and adrenal hyperplasia groups (both P > 0.05). Hypertensive patients with hyperaldosteronism appear to exhibit deteriorative effects on both vascular structure and function, independent of hypertension.

Cardiovascular risk in primary aldosteronism: A systematic review and meta-analysis

AIM

This study aimed to evaluate whether the increased cardiovascular risk and the incidence of cerebrovascular (CCV) events in hypertensive patients were related to primary aldosteronism (PA).

METHODS

The PubMed, EmBase, and the Cochrane Central Register of Controlled Trials were searched to evaluate the risk of CCV in PA patients and compared to essential hypertension (EH) patients. The mean differences (MD) and the risk ratios (RR) were calculated to assess the risk of main outcomes, such as stroke, coronary artery disease, left ventricular hypertrophy (LVH), levels of systolic blood pressure (SBP), diastolic blood pressure (DBP), blood glucose, and urinary potassium.

RESULTS

We identified 31 individual studies including 4546 patients in PA group and 52,284 patients in EH group. Our results revealed that PA was significantly associated with increased risk of stroke (RR=2.03, 95% CI = 1.71-2.39, Pheterogeneity = .331, I = 12.7%), coronary artery disease (RR = 1.67, 95% CI = 1.23-2.25, Pheterogeneity = .043, I = 48.3%), and LVH (RR = 1.54, 95% CI = 1.29-1.83, Pheterogeneity = .004, I = 62.6%) when compared with those in the EH group. Moreover, PA group had significantly increased levels of SBP (WMD = 4.14, 95% CI = 2.60-5.68, Pheterogeneity < .001, I = 84.3%), DBP (WMD = 2.65, 95% CI = 1.83-3.47, Pheterogeneity < .001, I = 77.7%), and urinary potassium (SMD = 0.04, 95% CI = -0.03-0.11, Pheterogeneity = .827, I = 0%) when compared to EH group. However, no significant difference was observed in the levels of blood glucose between the groups.

CONCLUSIONS

These findings suggested that PA significantly increased the risk of cardiac and cerebrovascular complications. In addition, patients with PA might benefit from a periodic assessment of CCV risk.

Renal artery stenosis and left ventricular hypertrophy: an updated review and meta-analysis of echocardiographic studies

AIM

Data on left ventricular hypertrophy (LVH) in patients with renal artery stenosis (RAS) and its regression following renal revascularization are scanty. We performed a meta-analysis to provide comprehensive information on this clinically relevant issue.

METHODS

Full articles providing data on: LVH, as assessed by echocardiography, in RAS patients as compared with essential hypertensive counterparts; changes of left ventricular (LV) mass index after renal artery revascularization were considered.

RESULTS

A total of 905 study participants (RAS = 446, essential hypertensive = 459) of both sex were included in nine studies. Pooled LV mass index was higher in RAS than in essential hypertensive patients (140.4 ± 11.1 g/m versus 121.8 ± 6.2 g/m, standard mean difference being 0.41 ± 0.07 [95% confidence interval (CI) 0.27-0.51, P < 0.001]. Among 360 RAS patients undergone renal revascularization from eight studies, baseline and post-intervention pooled mean LV mass index values were 129.0 ± 10.2 g/m and 115.5 ± 9.9 g/m, respectively, the standard mean difference being-0.36 ± 0.06 (95% CI from -0.47 to -0.25, P < 0.001). These findings were unaffected by publication bias or single study effect.

CONCLUSION

Our meta-analysis indicates that RAS patients have an increased likelihood of LVH compared with essential hypertensive counterparts and renal artery revascularization has a beneficial effect on LV structure, as reflected by a significant decrease in LV mass index.

Cardiovascular events and target organ damage in primary aldosteronism compared with essential hypertension: a systematic review and meta-analysis

BACKGROUND

There is conflicting evidence, relying on heterogeneous studies, as to whether aldosterone excess is responsible for an increased risk of cardiovascular and cerebrovascular complications in patients with primary aldosteronism. We aimed to assess the association between primary aldosteronism and adverse cardiac and cerebrovascular events, target organ damage, diabetes, and metabolic syndrome, compared with the association of essential hypertension and these cardiovascular and end organ events, by integrating results of previous studies.

METHODS

We did a meta-analysis of prospective and retrospective observational studies that compared patients with primary aldosteronism and essential hypertension, to analyse the association between primary aldosteronism and stroke, coronary artery disease (as co-primary endpoints), atrial fibrillation and heart failure, target organ damage, metabolic syndrome, and diabetes (as secondary endpoints). We searched MEDLINE and Cochrane Library for articles published up to Feb 28, 2017, with no start date restriction. Eligible studies compared patients with primary aldosteronism with patients with essential hypertension (as a control group) and reported on the clinical events or endpoints of interest. We also compared primary aldosteronism subtypes, aldosterone-producing adenoma, and bilateral adrenal hyperplasia.

FINDINGS

We identified 31 studies including 3838 patients with primary aldosteronism and 9284 patients with essential hypertension. After a median of 8·8 years (IQR 6·2-10·7) from the diagnosis of hypertension, compared with patients with essential hypertension, patients with primary aldosteronism had an increased risk of stroke (odds ratio [OR] 2·58, 95% CI 1·93-3·45), coronary artery disease (1·77, 1·10-2·83), atrial fibrillation (3·52, 2·06-5·99), and heart failure (2·05, 1·11-3·78). These results were consistent for patients with aldosterone-producing adenoma and bilateral adrenal hyperplasia, with no difference between these subgroups. Similarly, primary aldosteronism increased the risk of diabetes (OR 1·33, 95% CI 1·01-1·74), metabolic syndrome (1·53, 1·22-1·91), and left ventricular hypertrophy (2·29, 1·65-3·17).

INTERPRETATION

Diagnosing primary aldosteronism in the early stages of disease, with early initiation of specific treatment, is important because affected patients display an increased cardiovascular risk compared with patients with essential hypertension.

FUNDING

None.

Combination of β Adrenergic Receptor Block and Renin-Angiotensin System Inhibition Diminished the Angiotensin II-Induced Vasoconstriction and Increased Bradykinin-Induced Vasodilation in Hypertension

In hypertension, the combination therapy is frequently used to obtain a better therapeutic effect and reduce adverse effects. One effective combination is with inhibitors and β-blockers of renin–angiotensin system. Although the mechanisms of action of each drug are already known, the antihypertensive mechanism is more complex and therefore the combined treatment mechanism is unclear. Specifically, the effect of the treatments of angiotensin-converting enzyme inhibitor or AT₁ receptor antagonist with β-blocker on the angiotensin II and bradykinin reactivity has not been studied. For this reason, we evaluated the interaction between propranolol and captopril or losartan on vascular reactivity to bradykinin and angiotensin II in spontaneously hypertensive rat. We constructed concentration–response curves to angiotensin II and bradykinin after treatment of SHR with propranolol–captopril or propranolol–losartan by using rat aortic rings. While losartan or captopril with propranolol potentiated bradykinin-induced vasodilation effect, the propranolol–losartan interaction decreased the angiotensin II-induced vasoconstriction. In addition, the combinations did not reduce the heart rate significantly. These results suggest that the combined therapy decreased blood pressure to normotensive values and showed less effect for angiotensin II and greater effect for bradykinin than monotherapy which could contribute in the antihypertensive effect.

Microvascular structure as a prognostically relevant endpoint

Remodelling of subcutaneous small resistance arteries, as indicated by an increased media-to-lumen ratio, is frequently present in hypertensive, obese, or diabetic patients. The increased media-to-lumen ratio may impair organ flow reserve. This may be important in the maintenance and, probably, also in the progressive worsening of hypertensive disease. The presence of structural alterations represents a prognostically relevant factor, in terms of development of target organ damage or cardiovascular events, thus allowing us a prediction of complications in hypertension. In fact, media-to-lumen ratio of small arteries at baseline, and possibly their changes during treatment may have a strong prognostic significance. However, new, non-invasive techniques are needed before suggesting extensive application of the evaluation of remodelling of small arteries for the cardiovascular risk stratification in hypertensive patients. Some new techniques for the evaluation of microvascular morphology in the retina, currently under clinical investigation, seem to represent a promising and interesting future perspective. The evaluation of microvascular structure is progressively moving from bench to bedside, and it could represent, in the near future, an evaluation to be performed in all hypertensive patients, to obtain a better stratification of cardiovascular risk, and, possibly, it might be considered as an intermediate endpoint in the evaluation of the effects of antihypertensive therapy, provided that a demonstration of a prognostic value of non-invasive measures of microvascular structure is made available.

Adrenalectomy is comparable with medical treatment for reduction of left ventricular mass in primary aldosteronism: meta-analysis of long-term studies

BACKGROUND

Primary aldosteronism (PA) is associated with an increase in left ventricular (LV) mass beyond the amount needed to compensate the hypertension-related workload. Available evidence suggests effectiveness of surgical treatment of PA in decreasing LV mass, whereas data on medical treatment are controversial. We have conducted a meta-analysis of long-term follow-up studies on surgical and medical treatment of PA to compare the effects of treatments on LV mass.

METHODS

Medline and Cochrane searches were performed including the following words: hyperaldosteronism, left ventricular mass, mineralocorticoid receptor antagonists, surgery, adrenalectomy, and follow-up studies. Studies published within 2013 focusing on cardiac effects of treatment and follow-up longer than 6 months were selected. Data extraction was performed independently by 2 authors.

RESULTS

Of 61 retrieved articles, 4 were included in the analysis. These studies enrolled 355 patients with PA who had an average follow-up of 4.0 years after unilateral adrenalectomy (n = 178) or treatment with mineralocorticoid receptor antagonists (n = 177). Despite greater effect of surgery over medical treatment in reducing blood pressure, meta-analysis of the selected studies demonstrated no significant difference in LV mass change between patients with PA who were treated with mineralocorticoid receptor antagonists or adrenalectomy (standard mean difference = 0.130; 95% confidence interval = -0.085 to 0.345; P = 0.24; I2 = 0%).

CONCLUSIONS

Available evidence indicates that reduction of LV mass is not different in PA patients treated with adrenalectomy or mineralocorticoid receptor antagonists.

Vascular wall extracellular matrix proteins and vascular diseases

Extracellular matrix proteins form the basic structure of blood vessels. Along with providing basic structural support to blood vessels, matrix proteins interact with different sets of vascular cells via cell surface integrin or non-integrin receptors. Such interactions induce vascular cell de novo synthesis of new matrix proteins during blood vessel development or remodeling. Under pathological conditions, vascular matrix proteins undergo proteolytic processing, yielding bioactive fragments to influence vascular wall matrix remodeling. Vascular cells also produce alternatively spliced variants that induce vascular cell production of different matrix proteins to interrupt matrix homeostasis, leading to increased blood vessel stiffness; vascular cell migration, proliferation, or death; or vascular wall leakage and rupture. Destruction of vascular matrix proteins leads to vascular cell or blood-borne leukocyte accumulation, proliferation, and neointima formation within the vascular wall; blood vessels prone to uncontrolled enlargement during blood flow diastole; tortuous vein development; and neovascularization from existing pathological tissue microvessels. Here we summarize discoveries related to blood vessel matrix proteins within the past decade from basic and clinical studies in humans and animals - from expression to cross-linking, assembly, and degradation under physiological and vascular pathological conditions, including atherosclerosis, aortic aneurysms, varicose veins, and hypertension.

Retinal arterial hypertrophy: the new LVH?

Prevention of target organ damage represents the El Dorado for clinicians who treat hypertension. Although many of the cardiovascular sequelae of chronic hypertension are due to large artery atherosclerosis, an equal number are due to small artery dysfunction. These microvascular complications include eye disease (retinopathy), kidney failure, diastolic dysfunction of the heart and small vessel brain disease leading to stroke syndromes, dementia and even depression. Examination of the retinal vasculature represents the only way to reliably derive information regarding small arteries responsible for these diverse pathologies. This review aims to summarise the rapidly accruing evidence indicating that easily observable abnormalities of retinal arteries reflect target organ damage elsewhere in the body of hypertensive patients. In tandem, we also present putative mechanisms by which hypertension and diabetes fundamentally change small artery structure and function and how these processes may lead to target organ damage.

Relation between carotid intima-media thickness and left ventricular mass in type 1 diabetes mellitus (from the Epidemiology of Diabetes Interventions and Complications [EDIC] Study)

Type 1 diabetes mellitus (DM) is associated with early atherosclerosis and increased cardiovascular mortality. The relation between carotid intima-media thickness (cIMT), a marker of subclinical atherosclerosis, and left ventricular (LV) mass, an independent predictor of cardiovascular morbidity, has not been previously studied in type 1 DM. The Epidemiology of Diabetes Interventions and Complications (EDIC) study is a multicenter observational study designed to follow up the Diabetes Control and Complications Trial (DCCT) cohort. LV mass was measured with cardiac magnetic resonance imaging at EDIC year 15 and common cIMT was assessed using B-mode ultrasound at EDIC year 12. Multivariable linear regression models were used to assess the relation between cIMT at year 12 and LV mass at year 15. In total 889 participants had cardiac magnetic resonance imaging and cIMT measurements available for these analyses. At EDIC year 15, mean age of the participants was 49 ± 7 years, mean DM duration was 28 ± 5 years, and 52% were men. Spearman correlation coefficient (r) between LV mass and cIMT was 0.33 (p <0.0001). After adjusting for basic covariates (machine, reader, age, and gender), a significant association between LV mass and cIMT (estimate 2.0 g/m(2) per 0.1-mm cIMT increment, p <0.0001) was observed. This association was decreased by the addition of systolic blood pressure, in particular 1.15 g/m(2) per 0.1-mm cIMT increment (p <0.0001), and to a lesser extent other cardiovascular disease risk factors. Furthermore, the relation observed between LV mass and cIMT was stronger in patients with shorter duration of DM. In conclusion, cIMT was an independent predictor of larger LV mass in a well-characterized population with type 1 DM.

Structural abnormalities of small resistance arteries in essential hypertension

Regardless of the mechanisms that initiate the increase in blood pressure, the development of structural changes in the systemic vasculature is the end result of established hypertension. In essential hypertension, the small arteries smooth muscle cells are restructured around a smaller lumen, and there is no net growth of the vascular wall, while in some secondary forms of hypertension, a hypertrophic remodeling may be detected. Also, in non-insulin-dependent diabetes mellitus, a hypertrophic remodeling of subcutaneous small arteries is present. The results from our own group have suggested that indices of small resistance artery structure, such as the tunica media to internal lumen ratio, may have a strong prognostic significance in hypertensive patients, over and above all other known cardiovascular risk factors. Therefore, the regression of vascular alterations is an appealing goal of antihypertensive treatment. Different antihypertensive drugs seem to have different effect on vascular structure, both in human and in animal models of genetic and experimental hypertension. A complete normalization of small resistance artery structure is demonstrated in hypertensive patients, after long-term and effective therapy with ACE inhibitors, angiotensin II receptor blockers and calcium antagonists. Few data are available in diabetic hypertensive patients; however, blockade of the renin-angiotensin system seems to be effective in this regard. In conclusion, there are several pieces of evidence that suggest that small resistance artery structure may be considered an intermediate endpoint in the evaluation of the effects of antihypertensive therapy; however, there are presently no data available about the prognostic impact of the regression of vascular structural alterations in hypertension and diabetes.

Effects of diabetes and hypertension on structure and distensibilty of human small coronary arteries

OBJECTIVES

Previous studies have demonstrated that hypertension and diabetes induce significant structural remodelling of resistance arteries from various vascular beds. The hypothesis of this study is that structural alterations of small coronary arteries may occur during hypertension and diabetes. This study is the first to compare human coronary small resistance artery structure from normotensive and hypertensive patients, with and without diabetes undergoing coronary arterial bypass graft surgery.

METHODS

Small arteries were dissected from the atrial appendage removed from nondiabetic normotensive patients, nondiabetic hypertension and diabetic normotensive patients and hypertensive diabetic patients. Arteries were mounted in a pressure myograph and lumen diameter and wall thickness were measured across the pressure range of 3-100 mmHg to assess vessel structure and distensibility.

RESULTS

There were no significant differences in the lumen diameter, wall thickness, wall-to-lumen ratio and cross-sectional area of arteries in all groups. Arteries from nondiabetic patients with hypertension demonstrated decreased distensibility compared with nondiabetic normotensive patients. There is no difference in distensibility between vessels from diabetic hypertensive patients and either diabetic or nondiabetic normotensive patients.

CONCLUSION

Neither diabetes nor hypertension appears to have influenced arterial structure which may indicate that successful treatment of hypertension is associated with normal vascular structure in coronary small arteries.

Nitric oxide synthase-dependent vasodilation of human subcutaneous arterioles correlates with noninvasive measurements of endothelial function

BACKGROUND

Noninvasive measurements of endothelial function predict future adverse cardiovascular events, but offer limited opportunities for mechanistic insights into phenotypic observations. Subcutaneous adipose arterioles, accessible through minimally invasive methods, provide an opportunity for complimentary mechanistic studies. Limited data relating subcutaneous arteriolar endothelial function, cardiovascular risk factors, and noninvasive measurements of endothelial function currently exist.

METHODS

Forty-four subjects underwent noninvasive studies of endothelial function (brachial reactivity (flow-mediated dilation (FMD) and digital pulse arterial tonometry (PAT)) and measurements of endothelial-dependent vasodilation of gluteal subcutaneous arterioles to acetylcholine. Arteriolar endothelial function was measured (i) percent vasodilation to maximal acetylcholine dose (10(-5) mol/l) and (ii) total area under the curve (AUC) for the entire acetylcholine dose-response curve (total AUC-acetylcholine (Ach), doses 10(-10)-10(-5) mol/l).

RESULTS

Acetylcholine responses were almost completely nitric oxide (NO) dependent. Total AUC-Ach predicted FMD and PAT, but maximal acetylcholine vasodilation was not associated with these measures. A history of hypertension, diabetes, smoking, and low-density lipoprotein cholesterol levels were independent predictors of total AUC-Ach. In regression models, total AUC-Ach independently predicted FMD.

CONCLUSIONS

Acetylcholine vasodilator responses in human gluteal subcutaneous arterioles are NO synthase dependent and correlate with cardiac risk factors and in vivo measures of endothelial function. These data suggest subcutaneous arterioles offer an opportunity for translational studies of mechanisms of modulating NO bioavailability relevant to in vivo endothelial function measures.

Diagnosis and treatment of primary aldosteronism

A few simple rules can allow physicians to successfully identify many patients with arterial hypertension caused by PA among the so-called essential hypertensive patients. The hyperaldosteronism and the hypokalemia can be cured with adrenalectomy in practically all of these patients. Moreover, in a substantial proportion of them, the blood pressure can be normalized or markedly lowered if a unilateral cause of PA is discovered. Hence, the screening for PA can be rewarding both for the patient and for the clinician, particularly in those cases where hypertension is severe and/or resistant to treatment, in which the removal of an APA can allow blood pressure to be brought under control despite withdrawal of, or a prominent reduction in, the number and doses of antihypertensive medications.

A comprehensive review of the clinical aspects of primary aldosteronism

Primary aldosteronism is much more common than previously thought. The high prevalence of primary aldosteronism, the damage this condition does to the heart, blood vessels and kidneys (which causes a high rate of cardiovascular events), along with the notion that a timely diagnosis followed by an appropriate therapy can correct the arterial hypertension and hypokalemia, justify efforts to search for primary aldosteronism in many patients with hypertension. Most centers can use a cost-effective strategy to screen for patients with primary aldosteronism. By contrast, the identification of primary aldosteronism subtypes, which involves adrenal-vein sampling, should only be undertaken at tertiary referral centers that have experience in performing and interpreting this test. The identification of a curable form of primary aldosteronism can be beneficial for the patient. In some subgroups of patients with hypertension who are at high risk of primary aldosteronism or can benefit most from an accurate diagnosis, an aggressive diagnostic approach is necessary.

Diagnosis and treatment of primary aldosteronism

Primary aldosteronism involves more than 11% of hypertensive patients who are referred to specialized centers for the diagnosis and treatment of hypertension. If not diagnosed early it causes an excess damage to the heart, vessels and kidney, which translates into an cardiovascular events. Since these ominous consequences can be corrected with a timely diagnosis and an appropriate therapy, physicians should exercise a high degree of alert concerning the possibility that primary aldosteronism is present in hypertensive patients. The purpose of this review is to provide up-dated information on the strategy for case detection, the subtype differentiation and the management of primary aldosteronism.

Treatment of primary aldosteronism

The prevalence of primary hyperaldosteronism approaches 10% of all hypertensive patients, and besides efficient diagnostic procedures, effective treatment is of increasing importance to reverse increased morbidity and mortality. Aldosterone-producing adenoma and unilateral adrenal hyperplasia are amenable to cure by endoscopic adrenalectomy. Bilateral adrenal hyperplasia (micro- or macronodular), which comprises two-thirds of primary hyperaldosteronism, is treated primarily by mineralocorticoid receptor antagonists (starting dose 12.5-25mg/day spironolactone with titration up to 100mg/day, alternatively 50-100mg/day eplerenone). If blood pressure is not normalised by this first-line treatment, additional treatment with potassium-sparing diuretics (amiloride or triamterene) or calcium channel antagonists is necessary. The start of medication should be closely monitored by serum electrolyte and creatinine controls.

Hypertrophic remodeling of subcutaneous small resistance arteries in patients with Cushing's syndrome

OBJECTIVE

Structural alterations of small resistance arteries in essential hypertensive patients (EH) are mostly characterized by inward eutrophic remodeling. However, we observed hypertrophic remodeling in patients with renovascular hypertension, in those with acromegaly, as well as in patients with non-insulin-dependent diabetes mellitus, suggesting a relevant effect of humoral growth factors on vascular structure, even independent from the hemodynamic load. Cortisol may stimulate the renin-angiotensin system and may induce cardiac hypertrophy. However, presently no data are available about small artery structure in patients with Cushing's syndrome.

SUBJECTS

We have investigated the structure of sc small resistance arteries in 12 normotensive subjects (NT), in 12 EH subjects, and in eight patients with Cushing's syndrome (CS). Small arteries from sc fat were dissected and mounted on a micromyograph. The normalized internal diameter, media thickness, media to lumen ratio, and the media cross-sectional area were measured, as well as indices of oxidative stress.

RESULTS

Demographic variables were similar in the three groups, except for clinic blood pressure. The media to lumen ratio was significantly greater in EH and CS, compared with NT; no difference was observed between EH and CS. The media cross-sectional area was significantly greater in CS compared with EH and with NT. An increased vascular oxidative stress was present in CS, as demonstrated by increased levels of superoxide anions, cyclooxygenase-1 and endothelial nitric oxide synthase in the microvessels.

CONCLUSION

Our results suggest the presence of hypertrophic remodeling in sc small resistance arteries of CS, probably as a consequence of growth-promoting properties of circulating cortisol and/or increased vascular oxidative stress.

Cardiovascular complications in patients with pheochromocytoma: a mini-review

Phaeochromocytomas are rare neuroendocrine tumours secreting high levels of catecholamines, able to exert serious metabolic and cardiovascular effects. The serious and potentially lethal cardiovascular complications of these tumours are due to the potent effects of secreted catecholamines, especially noradrenaline, the main transmitter released from sympathetic nerve terminals. Hypertension, tachycardia, pallor, headache and anxiety, usually dominate the clinical presentation. Occasionally, patients with predominantly epinephrine-secreting tumours present hypotension or even shock. Other cardiovascular complications of pheochromocytoma include ischaemic heart disease, acute myocardial infarction, cardiac arrhythmias, heart failure due to toxic cardiomyopathy, or pulmonary edema. Catecholamines have been shown to influence the extracellular matrix with collagen deposition and subsequent fibrosis in the arterial wall and in the myocardium. These morphofunctional changes of the myocardium and of arterial wall can be emphasized by ultrasound imaging. Indeed, ultrasound imaging of the myocardium and arterial wall not only identifies wall thickness but also contains information on texture that may be revealed by acoustic tissue characterization. The latter can be quantified through videodensitometric analysis of echographic images or through ultrasonic integrated backscatter signal analysis. This paper reviews cardiovascular complications in patients with pheochromocytoma and utility of the new ultrasound technique as backscatter signal. It is useful for evaluating preclinical pathological morphofunctional changes of the myocardium and arterial wall, characterized by increased collagen content in pheochromocytoma patients. The recognition of early catecholamine-induced alterations in patients with pheochromocytoma, is important to prevent at least morbidity and mortality, before surgical treatment.

Relation of common carotid intima-media thickness with left ventricular mass caused by shared risk factors for hypertrophy

BACKGROUND

It is unclear whether the relationship between common carotid intima-media thickness (cCIMT) and left ventricular mass (LVM) is due to shared risk factors for atherosclerosis or for hypertrophy.

METHODS

In 525 hypertensive subjects at high cardiovascular risk, the relation of cCIMT to LVM and established vascular risk factors was studied.

RESULTS

CCIMT was positively related to LVM. In a multivariable model including age, gender, height, weight, and LVM, a 1-g increase in LVM related to an increase in cCIMT of 1.6 microm (95% confidence interval, 0.8-2.4). After adjustment for atherosclerotic risk factors, notably previous stroke or transient ischemic attack, peripheral arterial disease, lipid-lowering medication, albuminuria and current smoking, the relation remained unchanged. In contrast, addition of systolic and diastolic blood pressure and hypertension treatment attenuated Beta for the relation between cCIMT and LVM with 19% to 1.3 microm (95% confidence interval, 0.2-2.2).

CONCLUSION

The relationship between cCIMT and LVM may be due to risk factors for hypertrophy rather than for atherosclerotic factors in a considerable proportion of patients.

Inappropriate Left Ventricular Mass in Patients With Primary Aldosteronism

Assessment of appropriateness of left ventricular mass (LVM) for a given workload may better stratify hypertensive patients. Inappropriate LVM may reflect the interaction of genetic and neurohumoral factors other than blood pressure playing a significant role in myocardial growth. Primary aldosteronism (PA) represents a clinical model useful in assessing the effect of aldosterone increase on LVM. The aim of this study was to evaluate the inappropriateness of LVM in patients with PA. In 125 patients with PA (54 females; adrenal hyperplasia in 73 and adenoma in 52 patients) and in 125 age-, sex-, and blood pressure–matched, essential hypertensive patients, echocardiography was performed. The appropriateness of LVM was calculated by the ratio of observed LVM to the predicted value using a reference equation. In all of the subjects plasma renin activity and aldosterone, as well as clinic and 24-hour blood pressure, were measured. The prevalence of inappropriate LVM was greater in patients with traditionally defined left ventricular hypertrophy (70% and 44%, respectively; P =0.02) but also in patients without left ventricular hypertrophy (17% and 9%, respectively; P =0.085). In PA patients, a correlation was observed between the ratio of observed:predicted LVM and the ratio of aldosterone:plasma renin activity levels ( r =0.29; P =0.003) or the postinfusion aldosterone concentration ( r =0.44; P =0.004; n=42). In conclusion, in patients with PA, the prevalence of inappropriate LVM is increased, even in the absence of traditionally defined left ventricular hypertrophy. The increase in aldosterone levels could contribute to the increase of LV mass exceeding the amount needed to compensate hemodynamic load.

A review of methods for assessment of coronary microvascular disease in both clinical and experimental settings

Obstructive disease of the large coronary arteries is the prominent cause for angina pectoris. However, angina may also occur in the absence of significant coronary atherosclerosis or coronary artery spasm, especially in women. Myocardial ischaemia in these patients is often associated with abnormalities of the coronary microcirculation and may thus represent a manifestation of coronary microvascular disease (CMD). Elucidation of the role of the microvasculature in the genesis of myocardial ischaemia and cardiac damage-in the presence or absence of obstructive coronary atherosclerosis-will certainly result in more rational diagnostic and therapeutic interventions for patients with ischaemic heart disease. Specifically targeted research based on improved assessment modalities is needed to improve the diagnosis of CMD and to translate current molecular, cellular, and physiological knowledge into new therapeutic options.

Preclinical cardiac involvement in phaeochromocytoma: a study with integrated backscatter

OBJECTIVE

It is well known that vascular and cardiac structure may be influenced by circulating neurohormonal factors. Our aim was to study the myocardial wall texture by integrated backscatter (IBS) analysis in patients with phaeochromocytoma (PHEO).

DESIGN

Fourteen patients with PHEO, 15 matched high-normal blood pressure (BP) subjects, 15 mild essential hypertensives and 15 normotensive controls underwent two-dimensional conventional ultrasonography and ultrasonic IBS of the myocardial wall. IBS analysis was performed at both interventricular septum and posterior wall levels. IBS values were expressed in decibels and corrected for the IBS values obtained within the pericardium (C-IBS). The systo-diastolic cyclical variations in IBS (CV-IBS), an index of myocardial contractile performance, were also evaluated.

RESULTS

Patients with PHEO showed C-IBS values comparable to those of hypertensive patients, and significantly higher than those of high-normal BP subjects and controls at both septum and posterior wall levels (P < 0.001 for all). In PHEO patients, CV-IBS was lower than that of normotensive, high-normal BP subjects and hypertensive patients, at both septum and posterior wall levels (P < 0.001 for all). An inverse relationship was found in the PHEO group between 24-h urinary normetanephrine and CV-IBS of both septum (r(2) = -0.29, P < 0.05) and posterior wall (r(2) = -0.46, P < 0.05).

CONCLUSIONS

Our results show that patients with PHEO have myocardial remodelling characterized by increased myocardial fibrosis, confirmed by an increase in the overall myocardial backscatter level measured. The observed decrease in the magnitude of CV-IBS suggests an impairment of myocardial contractile performance. These results may provide insights into the role of catecholamines in left ventricular (LV) structure and function in PHEO.

Primary aldosteronism: cardiovascular, renal and metabolic implications

For many years primary aldosteronism was considered a relatively benign form of hypertension. This assumption reflects the primacy accorded to elevated levels of angiotensin in terms of deleterious cardiovascular effects, and the fact that in primary aldosteronism renin and angiotensin levels are low. We now know that primary aldosteronism causes a constellation of cardiovascular, renal and metabolic sequelae which make it far from benign and that these are not merely effects of blood pressure elevation. In primary aldosteronism, tissue damage, on several indices, is higher than in age-, sex- and blood pressure-matched controls, reflecting the ability of inappropriately elevated aldosterone for salt status to produce structural and functional changes over and above those produced by high blood pressure.

Is adrenal venous sampling necessary in all patients with hyperaldosteronism before adrenalectomy?

PURPOSE

To evaluate whether selective rather than universal use of adrenal vein sampling (AVS) may be warranted in patients with hyperaldosteronism to characterize and lateralize disease before adrenalectomy.

MATERIALS AND METHODS

Fifty-nine consecutive patients with biochemically diagnosed hyperaldosteronism underwent unilateral adrenalectomy at a single center during a 10-year period. In one group (n = 30), adrenalectomy was based on computed tomography (CT) only; in another (n = 29), it was based on CT and AVS. The indication for AVS was equivocal CT finding (n = 26) or patient request (n = 3). Outcome variables were postoperative serum potassium and aldosterone levels, number of hypertensive medications, and mean arterial blood pressure at 6 months.

RESULTS

Preoperatively, both groups were matched for age, years of hypertension, mean arterial blood pressure, and number of hypertensive medications. Average tumor sizes were 2 cm (range, 1-3 cm) in the CT-only group and 1 cm (range, 0-2.5 cm) in the CT/AVS group. Unilateral tumor was identified on CT in 30 patients (100%) in the CT-only group and in 17 patients (59%) in the CT/AVS group (P < .05). Postoperatively, aldosterone levels were lower in the CT-only group (6.3 ng/dL +/- 5.9 vs 13.5 ng/dL +/- 16; P < .05). Both groups had similar improvements in mean arterial blood pressure at 6 months (92 mm Hg +/- 12 vs 96 mm Hg +/- 9; P = .14), reductions in number of hypertensive medications (to 1.1 +/- 1.3 vs 1.2 +/- 1.1; P = .4), and improvements in hypokalemia (3.8 mEq/L +/- 0.5 vs 3.8 mEq/L +/- 0.5; P = .5).

CONCLUSIONS

The clinical impact of adrenalectomy was similar in both groups. CT can be used to reliably diagnose adenomas larger than 1.0 cm. AVS should be used when CT findings are equivocal or both adrenal glands are abnormal.

Long-term cardiac effects of adrenalectomy or mineralocorticoid antagonists in patients with primary aldosteronism

Exposure to excess aldosterone results in cardiac damage in hypertensive states. We evaluated the long-term cardiac structural and functional evolution in patients with primary aldosteronism after surgical or medical treatment. Fifty-four patients with primary aldosteronism were enrolled in a prospective study and were followed for a mean of 6.4 years after treatment with adrenalectomy (n=24) or spironolactone (n=30). At baseline, echocardiographic measurements of patients with primary aldosteronism were compared with those of 274 patients with essential hypertension. Patients with primary aldosteronism had greater left ventricular mass, more prevalent left ventricular hypertrophy, lower early:late-wave diastolic filling velocities ratio, and longer deceleration time than patients with essential hypertension but no differences in relative wall thickness and systolic function. During follow-up, average blood pressure was 135/82 and 137/82 mm Hg in patients treated with adrenalectomy and spironolactone, respectively. In the initial 1-year period, left ventricular mass decreased significantly only in adrenalectomized patients. Subsequent changes in left ventricular mass were greater in patients treated with spironolactone, with an overall change from baseline to the end of follow-up that was comparable in the 2 groups. Prevalence of hypertrophy decreased in both treatment groups, whereas diastolic parameters had only mild and nonsignificant improvement. Changes in blood pressure and pretreatment plasma aldosterone were independent predictors of left ventricular mass decrease in both treatment groups. Thus, in the long-term, both adrenalectomy and spironolactone are effective in reducing left ventricular mass in patients with primary aldosteronism, with effects that are partially independent of blood pressure changes.

The influence of serum aldosterone and the aldosterone-renin ratio on pulse wave velocity in hypertensive patients

OBJECTIVE

The aldosterone-renin ratio (ARR) is widely used to screen for primary aldosteronism, and may reflect a relative excess of aldosterone secretion compared with renin secretion. Excess aldosterone may have a detrimental effect on vascular stiffness. We therefore hypothesized that ARR and aldosterone are independently correlated with pulse wave velocity (PWV) in hypertensive patients.

METHODS

The study consisted of 438 hypertensive patients. Serum aldosterone and plasma renin activity were measured in a sitting position using standard techniques. The PWV was determined by measuring the heart to femoral PWV (hfPWV) and brachial to ankle PWV with a VP-2000 pulse wave unit.

RESULTS

Group 1 was defined as patients with ARR of at least 20 (n = 53) with serum aldosterone >or= 12 ng/dl, while the remainder comprised group 2. Comparisons between the two groups reveal group 1 tended to have higher age, significantly higher proportion of women and higher systolic/diastolic blood pressure. Patients in group 1 also had a significantly higher index of central arterial stiffness (hfPWV 1048 +/- 202 vs 978 +/- 182, P = 0.010) compared with group 2. Multiple linear regression revealed that aldosterone, but not the ARR, is significantly associated with hfPWV but not brachial to ankle PWV, after controlling for age, systolic blood pressure and heart rate at the time of PWV measurement, body mass index, gender, low-density lipoprotein-cholesterol, triglyceride, high-density lipoprotein-cholesterol, blood pressure medication and statins.

CONCLUSIONS

Serum aldosterone is significantly associated with central aortic PWV in hypertensive patients. The results demonstrate a possible role for aldosterone in developing central aortic stiffness and increased PWV in hypertensive patients.

Increased intima–media thickness of the common carotid artery in primary aldosteronism in comparison with essential hypertension

BACKGROUND

Aldosterone contributes to the accumulation of collagen fibers and extracellular matrix in arterial wall. The aim of this study was to compare intima-media thickness (IMT) of the common carotid artery and carotid bifurcation in patients with primary aldosteronism, essential hypertension and healthy controls.

METHODS

Carotid ultrasound studies were carried out in 33 patients aged 42-72 years with primary aldosteronism, 52 patients with essential hypertension and in 33 normotensive controls.

RESULTS

The patients with primary aldosteronism had significantly higher IMT of the common carotid artery than patients with essential hypertension and controls (0.987 +/- 0.152 mm; 0.892 +/- 0.154 mm versus 0.812 +/- 0.124 mm; P < 0.001; P < 0.05). There was also significantly higher IMT of the common carotid in patients with essential hypertension compared to control group (0.892 +/- 0.154 mm versus 0.812 +/- 0.124 mm; P < 0.01). The differences between both hypertensive groups remained statistically significant after adjustment for age and 24-h systolic blood pressure (P = 0.001). The differences of the IMT in the carotid bifurcation were statistically significant only between patients with primary aldosteronism and controls (1.157 +/- 0.243 mm versus 0.994 +/- 0.199 mm; P <0.05).

CONCLUSION

Patients with primary aldosteronism have increased common carotid IMT compared to the patients with essential hypertension. This finding could be caused by the deleterious effects of aldosterone excess on the fibrosis and thickening of the arterial wall, mainly in the straight segments of vessels.

Renin-angiotensin system and cardiovascular risk

The renin-angiotensin system is a major regulatory system of cardiovascular and renal function. Basic research has revealed exciting new aspects, which could lead to novel or modified therapeutic approaches. Renin-angiotensin system blockade exerts potent antiatherosclerotic effects, which are mediated by their antihypertensive, anti-inflammatory, antiproliferative, and oxidative stress lowering properties. Inhibitors of the system-ie, angiotensin converting enzyme inhibitors and angiotensin receptor blockers, are now first-line treatments for hypertensive target organ damage and progressive renal disease. Their effects are greater than expected by their ability to lower blood pressure alone. Angiotensin receptor blockers reduce the frequency of atrial fibrillation and stroke. Renin-angiotensin system blockade delays or avoids the onset of type 2 diabetes and prevents cardiovascular and renal events in diabetic patients. Thus, blockade of this system will remain a cornerstone of our strategies to reduce cardiovascular risk.

Aldosterone—A Hormone of Cardiovascular Adaptation and Maladaptation

Aldosterone stimulates reabsorption of sodium, sustaining blood volume and pressure in the face of salt deprivation or extracellular fluid depletion. The steroid also stimulates excretion of potassium, protecting extracellular fluid from excessive levels of that ion. These two actions are relatively rapid and clearly adaptive when appropriately initiated and terminated, but maladaptive when prolonged or excessive, causing hypertension and electrolyte imbalance. Aldosterone and other mineralocorticoids exert slower, direct effects on cells in the heart, kidneys, and vessels, leading to hypertrophy, fibrosis, and dysfunction contributing to degenerative cardiovascular diseases. The maladaptive actions of aldosterone are exacerbated by sodium chloride, angiotensin, endothelin, and certain growth factors. Damage can be minimized by antagonists of aldosterone receptors, inhibitors of the renin system, depletion of salt, and repletion of potassium and magnesium. Specific inhibitors of fibrosis and hypertrophy, and more effective inhibitors of the renin system should be useful in the future.

Renal artery stenosis and accelerated atherosclerosis: which comes first?

Renal artery stenosis (RAS) is usually observed in hypertensive patients with extensive atherosclerosis. There is some evidence that in these patients the atherosclerotic process and the consequent target-organ damage is more severe than in hypertensive patients without RAS. In this review we will entertain the hypothesis that some of the humoral factors that are activated by RAS may contribute to accelerate the progression of atherosclerosis. Several studies identified RAS as a predictor of cardiovascular events in high-risk patients, although in most cases the contribution of blood pressure per se to the progression of vascular lesions could not be determined. As a result of experimental RAS, hypertension and increased oxidative stress are stimuli for atherosclerosis as well as cardiac and renal damage. In the presence of RAS, the renin-angiotensin system is stimulated, and it has been shown that angiotensin II exerts proinflammatory, pro-oxidant and procoagulant activities in experimental models and humans. The potential contribution of reactive oxygen species to the prohypertensive and proatherosclerotic effects of RAS is supported by evidence that nicotinamide adenine dinucleotide phosphate, reduced form oxidase is specifically stimulated by angiotensin II, an activity not shared by epinephrine. Moreover, angiotensin II triggers the release of aldosterone, endothelin 1, thromboxane A2 and other derivatives of the arachidonic acid metabolism, all of which can further and independently aggravate cardiovascular damage. Epidemiological and experimental evidence so far available suggests that accelerated atherosclerosis can be both the cause and the consequence of RAS.