Relationship between left ventricular mass and endothelium-dependent vasodilation in never-treated hypertensive patients

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

Aims

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

Methods and results

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

Conclusions

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

Forearm Resistance-Vessel Dilatation Function During Reactive Hyperemia in Patients With Resistant Hypertension

BACKGROUND

Forearm blood flow (FBF) measured during reactive hyperemia by venous-occlusion plethysmography assesses resistance-vessel dilatation function but has never been investigated in resistant hypertension. The aim was to evaluate the independent correlates of forearm resistance-vessel function parameters in resistant hypertensives.

METHODS

In a cross-sectional study, 274 resistant hypertensives performed 24-hour ambulatory blood pressure (BP) monitoring, 2D-echocardiography, aortic pulse wave velocity, and venous-occlusion plethysmography with baseline and hyperemic FBF and vascular resistance measurements. A subsample of 103 patients also performed ultrasonographic brachial artery endothelial function examination. Independent correlates of baseline and hyperemic vascular parameters were assessed by multiple linear regressions.

RESULTS

Median (interquartile range) baseline FBF was 3.1 (2.4-4.0) ml/min/100ml of tissue, and during hyperemia mean FBF rose to 7.0 (5.2-9.4) ml/min/100ml of tissue. Baseline FBF and resistance were independently associated with left ventricular mass index (partial correlations -0.14 and 0.13, respectively), whereas hyperemic parameters were independently associated with body mass index (BMI) (inversely for FBF, partial correlation: -0.18 to -0.21) and with the nocturnal BP fall (directly for FBF, partial correlation: 0.12-0.15), after adjustments for age, sex, mean arterial pressure, and baseline vascular parameters. In a separate analysis, a larger brachial artery diameter was associated with higher hyperemic FBF, but there were no associations between resistance-vessel and conduit-vessel dilatation function parameters.

CONCLUSION

In patients with resistant hypertension, left ventricular mass was the only correlate of baseline FBF and resistance, whereas higher BMI and lower nocturnal BP fall were independently associated with lower FBF and higher resistance during reactive hyperemia.

Associations of Macro- and Microvascular Endothelial Dysfunction With Subclinical Ventricular Dysfunction in End-Stage Renal Disease

Patients with end-stage renal disease (ESRD) suffer high rates of heart failure and cardiovascular mortality, and we lack a thorough understanding of what, if any, modifiable factors contribute to cardiac dysfunction in these high-risk patients. To evaluate endothelial function as a potentially modifiable cause of cardiac dysfunction in ESRD, we investigated cross-sectional associations of macro- and microvascular dysfunction with left and right ventricular dysfunction in a well-controlled ESRD cohort. We performed comprehensive echocardiography, including tissue Doppler imaging and speckle-tracking echocardiography of the left and right ventricle, in 149 ESRD patients enrolled in an ongoing prospective, observational study. Of these participants, 123 also underwent endothelium-dependent flow-mediated dilation of the brachial artery (macrovascular function). Microvascular function was measured as the velocity time integral of hyperemic blood flow after cuff deflation. Impaired flow-mediated dilation was associated with higher left ventricular mass, independently of age and blood pressure: per 2-fold lower flow-mediated dilation, left ventricular mass was 4.1% higher (95% confidence interval, 0.49-7.7; P=0.03). After adjustment for demographics, blood pressure, comorbidities, and medications, a 2-fold lower velocity time integral was associated with 9.5% higher E/e' ratio (95% confidence interval, 1.0-16; P=0.03) and 6.7% lower absolute right ventricular longitudinal strain (95% confidence interval, 2.0-12; P=0.003). Endothelial dysfunction is a major correlate of cardiac dysfunction in ESRD, particularly diastolic and right ventricular dysfunction, in patients whose volume status is well controlled. Future investigations are needed to determine whether therapies targeting the vascular endothelium could improve cardiac outcomes in ESRD.

Serum phosphorus levels are associated with endothelial dysfunction in hypertensive patients

BACKGROUND AND AIMS

Recent data demonstrated that serum phosphorus, within the normal range, is an independent predictor of atherosclerotic cardiovascular disease, independently of renal function. Traditional cardiovascular risk factors are important mediators of endothelial dysfunction, the early step of atherosclerosis. We designed this study to evaluate a possible correlation between serum phosphorus and endothelium-dependent vasodilation, evaluated by the strain-gauge plethysmography, in naïve hypertensives.

METHODS AND RESULTS

We investigated by strain-gauge plethysmography, the relationship between forearm blood flow (FBF) response to acetylcholine (ACh) and serum phosphorus in 500 patients with uncomplicated, never-treated, essential hypertension, divided by phosphorus tertiles. There were no significant differences among tertiles with the exclusion of forearm blood flow (FBF). Phosphorus (β = -0.454; P = 0.0001), estimated-glomerular filtration rate (e-GFR, by CKD-EPI formula) (β = 0.261; P = 0.0001), gender (β = 0.215; P = 0.0001), BMI (β = -0.086; P = 0.018), HDL-cholesterol (β = 0.077; P = 0.036) were significantly related to endothelium-dependent vasodilation. In an additional analysis including serum high sensitivity C-reactive protein (hs-CRP) (measured in 400 patients) in the same model, the link between serum phosphorus and ACh-stimulated FBF did not change (β = -0.422; P = 0.0001). Clinically relevant, 0.1 mg of phosphorus increase is associated with a reduction of 22% of ACh-stimulated FBF. On multiple logistic regression analysis, the risk of endothelial dysfunction was about twice higher in patients in the second (OR = 1.754, 95% CI = 1.055-2.915; P = 0.030) and three-fold higher in the third tertile (OR = 2.939, 95% CI = 1.598-5.408; P = 0.0001) in comparison with those in the first tertile of phosphorus.

CONCLUSION

An impaired ACh-stimulated FBF is associated with serum phosphorus levels, within the normal range, in hypertensives.

Endothelial Nogo-B regulates sphingolipid biosynthesis to promote pathological cardiac hypertrophy during chronic pressure overload

We recently discovered that endothelial Nogo-B, a membrane protein of the ER, regulates vascular function by inhibiting the rate-limiting enzyme, serine palmitoyltransferase (SPT), in de novo sphingolipid biosynthesis. Here, we show that endothelium-derived sphingolipids, particularly sphingosine-1-phosphate (S1P), protect the heart from inflammation, fibrosis, and dysfunction following pressure overload and that Nogo-B regulates this paracrine process. SPT activity is upregulated in banded hearts in vivo as well as in TNF-α-activated endothelium in vitro, and loss of Nogo removes the brake on SPT, increasing local S1P production. Hence, mice lacking Nogo-B, systemically or specifically in the endothelium, are resistant to the onset of pathological cardiac hypertrophy. Furthermore, pharmacological inhibition of SPT with myriocin restores permeability, inflammation, and heart dysfunction in Nogo-A/B-deficient mice to WT levels, whereas SEW2871, an S1P₁ receptor agonist, prevents myocardial permeability, inflammation, and dysfunction in WT banded mice. Our study identifies a critical role of endothelial sphingolipid biosynthesis and its regulation by Nogo-B in the development of pathological cardiac hypertrophy and proposes a potential therapeutic target for the attenuation or reversal of this clinical condition.

Association of Endothelial and Mild Renal Dysfunction With the Severity of Left Ventricular Hypertrophy in Hypertensive Patients

BACKGROUND

The association between impaired renal function and increase left ventricular mass was shown to be related to increase in arterial stiffness, which indicates that vascular homeostasis and remodeling may impact the left ventricular hypertrophy (LVH) in patients with renal dysfunction.

METHODS

We measured the peripheral arterial reactive hyperemia index (RHI) and estimated glomerular filtration rate (eGFR) in 317 hypertensive patients comprising 115 normal RHI (RHI > 1.67) and normal eGFR (eGFR ≥ 90ml/min per 1.73 m(2)), 136 low RHI (RHI ≤ 1.67), 27 low eGFR (60 ≤ eGFR < 90ml/min per 1.73 m(2)) and 39 low RHI combined with low eGFR.

RESULTS

Multivariate logistic regression analysis identified lg RHI (odds ratio (OR): 0.001, 95% confidence interval (CI): 10(-6) to 0.426, P = 0.024) and lg eGFR (OR: 0.009, 95% CI: 10(-4) to 0.414, P = 0.016) as independent factors correlated with LVH respectively in hypertensive patients. Compared with normal RHI and eGFR patients, the extent of LVH in patients with either low RHI (OR: 1.224 95% CI: 0.451 to 3.327, P = 0.691) or low eGFR (OR: 0.593 95% CI: 0.070 to 5.037, P = 0.632) did not significantly increase, while it increased significantly in patients with low RHI combined with low eGFR (OR: 4.629 95% CI: 1.592 to 13.458, P = 0.005).

CONCLUSIONS

The concurrence of endothelial and mild renal dysfunction was significantly associated with the severity of LVH in hypertensive patients.

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

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

Metabolic syndrome and right ventricle: an updated review

The cluster of metabolic and hemodynamic abnormalities which characterize the metabolic syndrome (MS) is responsible for subclinical cardiac and extra-cardiac damage such as left ventricular hypertrophy, diastolic dysfunction, carotid atherosclerosis and microalbuminuria. The development of different non-invasive imaging methods enabled a detail investigation of right ventricular structure and function, and revealed that right ventricular remodeling followed changes in the left ventricular structure and function in patients with arterial hypertension, diabetes or obesity. Previous investigations also reported that the coexistence of two components of the MS induced more significant cardiac remodeling than the presence of only one MS risk-factor. The relationship between different components of the MS (increased blood pressure, abdominal obesity, increased fasting glucose level and dyslipidemia) and right ventricular remodeling could be explained by several hemodynamic and non-hemodynamic mechanisms. However, the association between right ventricular remodeling and the MS has not been sufficiently investigated so far. The aim of this article was to review recent articles focusing on the association between metabolic syndrome components and the metabolic syndrome itself with impairments in right ventricular structure and function assessed by different imaging techniques.

Brachial artery diameter and the right ventricle: the Multi-Ethnic Study of Atherosclerosis-right ventricle study

BACKGROUND

Endothelial dysfunction is associated with left ventricular morphology and long-term cardiovascular outcomes. The purpose of this study was to assess the relationship between both baseline brachial artery diameter and peripheral endothelial function (assessed by brachial artery ultrasonography) and right ventricular (RV) mass, RV end-diastolic volume (RVEDV), and RV ejection fraction (RVEF).

METHODS

The Multi-Ethnic Study of Atherosclerosis (MESA) performed cardiac MRI and brachial artery ultrasonography on participants without clinical cardiovascular disease. Baseline brachial artery diameter and flow-mediated dilation were assessed.

RESULTS

The mean age was 60.9 years, and 49.4% of subjects were men (n = 2,425). In adjusted models, larger brachial artery diameter was strongly associated with greater RV mass (β = 0.55 g, P &lt; .001), larger RVEDV (β = 3.99 mL, P &lt; .001), and decreased RVEF (β = -0.46%, P = .03). These relationships persisted after further adjustment for the respective left ventricular parameters. Flow-mediated dilation was not associated with RV mass or RVEF and was only weakly associated with RVEDV.

CONCLUSIONS

Brachial artery diameter is associated with greater RV mass and RVEDV, as well as lower RVEF. Changes in the systemic arterial circulation may have pathophysiologic links to pulmonary vascular dysfunction or abnormalities in RV perfusion.

Heart rate affects endothelial function in essential hypertension

Increased heart rate (HR) is a risk factor for cardiovascular morbidity and mortality in the general population and in some clinical conditions. Endothelial dysfunction is an adverse prognostic factor for cardiovascular events. The aim of the study was to evaluate the effect of HR on central hemodynamic parameters and endothelial function in hypertension. We evaluated forearm blood flow (FBF) response to intra-arterial infusion of acetylcholine (ACh) and sodium nitroprusside (SNP) in 30 patients with HR ≤60 min(-1) and 30 with HR ≥80 min(-1). The FBF was measured by strain-gauge plethysmography. Transesophageal atrial pacing was used to increase the HR. Radial artery applanation tonometry and pulse wave analysis were used to derive central aortic pressures and correlate hemodynamic indices. The FBF response to ACh is lower in hypertensives with HR ≤60 min(-1) than in those with HR ≥80 min(-1) (10.6 ± 4.2 vs. 13.6 ± 5.1 ml × 100 ml(-1) of tissue × min(-1), P < 0.001). Vascular resistance decreases to 9.3 ± 2.8 U in patients with lower HR versus 7.2 ± 2.1 U in those with higher HR (P = 0.002). The FBF response to SNP is similar in both groups. Central systolic and pulse pressure are higher in bradycardic patients than in those with HR ≥80 min(-1) (140 ± 8 vs. 131 ± 8 mmHg, P = 0.0001 and 49 ± 10 vs. 39 ± 11 mmHg, P = 0.0001). All central hemodynamic parameters decrease during incremental atrial pacing. Augmentation index is the strongest predictor of endothelial dysfunction at multivariate analysis. These findings demonstrate that low HR affects endothelium-dependent vasodilation in hypertension. Increased central aortic pressure and hemodynamic correlates seem to be the underlying mechanisms by which bradycardia interferes with endothelium-dependent reactivity.

Impaired endothelial responses in apparently healthy young people associated with subclinical variation in blood pressure and cardiovascular phenotype

BACKGROUND

A phenomenon of endothelial impairment, independent of classical cardiovascular risk factors, has been observed in young people. We identified subjects with persistently reduced, or declining, endothelial function during adolescence and early adulthood, without apparent cardiovascular risk, and investigated the clinical relevance of this finding.

METHODS

Endothelial vasomotor responses were assessed by brachial artery flow-mediated dilatation (FMD) at age 15 years in 47 subjects (22 males) who returned for a repeated measurement at age 25. Subjects underwent quantification of left ventricular mass (LVM) and function by cardiovascular magnetic resonance, central arterial stiffness by applanation tonometry, and common carotid artery intima-media thickness using ultrasound on their visit at age 25.

RESULTS

Individuals with low average FMD over 10-year period, although normotensive, had 5 mm Hg higher systolic blood pressure and, significantly greater LVM (73.48 ± 7.73 vs. 56.25 ± 9.54 g/m(2), P = 0.0001), carotid intima-media thickness (cIMT) (0.53 ± 0.06 vs. 0.47 ± 0.04 mm, P = 0.03), and pulse wave velocity (5.97 ± 0.63 vs. 5.29 ± 0.59 m/s, P = 0.02) than those with higher endothelial responses. Subjects with the greatest decline in FMD over 10 years had a significant increase in mean arterial pressure but similar cardiovascular phenotype.

CONCLUSION

Persistently reduced, or declining, endothelial function during adolescence, in the absence of overt cardiovascular disease, is a sensitive early marker associated with subclinical changes in blood pressure (BP) and an adverse cardiovascular phenotype. The findings highlight the potential importance of endothelial responses during adolescence in primary prevention strategies for hypertension.

Prevention of vascular dysfunction after preeclampsia: a potential long-term outcome measure and an emerging goal for treatment

Preeclampsia is increasingly being recognised as more than an isolated disease of pregnancy. In particular, preeclampsia has emerged as an independent risk factor for maternal cardiovascular disease and has recently been recognised as a risk factor for cardiovascular disease in children exposed in utero. Preeclampsia and cardiovascular disease may share important pathophysiological and molecular mechanisms and further investigation into these is likely to offer insight into the origins of both conditions. This paper considers the links between cardiovascular disease and preeclampsia and the implication of these findings for refinement of the management of patients whose care is complicated by preeclampsia.

Effects of statin treatment on endothelial function, oxidative stress and inflammation in patients with arterial hypertension and normal cholesterol levels

OBJECTIVE

Patients with arterial hypertension are characterized by impaired endothelial function and increased cardiovascular risk. Statins have been proposed as a potential treatment option in hypertension, even in those with normal low-density lipoprotein (LDL)-cholesterol levels. We tested whether fluvastatin reduces oxidative stress and inflammation, and improves endothelial function in patients with arterial hypertension and normal LDL-cholesterol.

METHODS

In a cross-over designed, double-blind randomized trial, 26 patients with arterial hypertension and LDL-cholesterol below 160 mg/dl were treated for 2 weeks with either placebo or fluvastatin 80 mg/day. Endothelium-dependent vasodilation (EDV) was assessed as the forearm blood flow (FBF) response to intra-arterial infusion of acetylcholine (ACH, 12 and 48 μg/min), and endothelium-independent vasodilation (EIV) as the FBF response to nitroprusside (3.2 and 12.8 μg/min). Furthermore, we measured reduced to oxidized glutathione (GSH/GSSG) ratio in red blood cells, total antioxidant capacity in plasma (TAC) and high-sensitivity C-reactive protein (hs-CRP) levels.

RESULTS

Fluvastatin lowered LDL-cholesterol from 118 ± 16 to 90 ± 25 mg/dl (P < 0.0001), but had no effect on blood pressure, high-density lipoprotein (HDL)-cholesterol or triglycerides. EDV and EIV were unaffected by fluvastatin treatment (e.g. increase of FBF 48 μg/min: 339 ± 285% during placebo versus 268 ± 194% during fluvastatin, n.s.). Finally, GSH/GSSG ratio, TAC and hs-CRP levels were similar between fluvastatin and placebo treatment.

CONCLUSION

Fluvastatin treatment did not improve endothelial function, oxidative stress or inflammation in patients with arterial hypertension and normal LDL-cholesterol levels. These data argue against the usefulness of statins in patients with arterial hypertension in the absence of hypercholesterolemia or other additional risk factors.

Decreased circulating endothelial progenitor cell levels and function in essential hypertensive patients with electrocardiographic left ventricular hypertrophy

The aim of this study was to explore the role of circulating endothelial progenitor cells (EPCs) and endothelial apoptotic microparticles in hypertensive patients with and without electrocardiographic left ventricular hypertrophy (LVH). Flow cytometry was used to assess endothelial cell apoptosis and circulating EPC level by quantification of circulating EPC markers (defined as CD34(+)CD133(+), CD34(+)KDR(+)) and endothelial apoptotic microparticles (defined as CD31(+)/annexin V(+)) in peripheral blood samples. The LVH was defined by ECG with the Cornell voltage criteria. In total, 128 hypertensive patients (83 men and 45 women, aged 59±14 years) were enrolled in this study, in which 107 patients (84%) showed no electrocardiographic evidence of LVH, and 21 patients (16%) fulfilled the LVH criteria by ECG. There were no significant differences in basic characteristics between the two groups, but hypertensive patients with LVH had a higher urine albumin excretion rate than those without LVH (P=0.027). Furthermore, hypertensive patients with LVH were shown to have decreased circulating EPC numbers (all P<0.05) and adhesive function compared with those without LVH (LVH vs. no LVH: 14±6 vs. 30±6 cells per high-power field, P<0.001). Increased numbers of endothelial apoptotic microparticles were noted in hypertensive patients with LVH (4.2±4.9 vs. 2.4±3.4%, P=0.115), although the difference was not significant. This study showed that essential hypertensive patients with electrocardiographic LVH evidence have decreased circulating EPC numbers and adhesive function compared with those without LVH. These findings may explain the pathogenetic processes that link hypertensive LVH and endothelial injury in cardiovascular disease.

Circulating levels of asymmetric dimethylarginine are an independent risk factor for left ventricular hypertrophy and predict cardiovascular events in pre-dialysis patients with chronic kidney disease

BACKGROUND

Several studies have related the circulating level of asymmetric dimethylarginine (ADMA) to cardiac remodeling and cardiovascular (CV) events in end-stage renal disease (ESRD) patients. Studies investigating this relationship in patients with pre-dialysis chronic kidney disease (CKD) are lacking.

METHODS

We enrolled 76 CKD patients (age, 46.7+/-14.3 years, 39 females) and 15 controls (age, 40.1+/-18.5 years, 6 females). Clinical parameters, blood biochemistry and echocardiographic findings were recorded, and plasma ADMA concentrations measured by high-performance liquid chromatography-mass spectrometry (HPLC-MS). Patients were prospectively followed up for a median of 15 (range, 6-24) months.

RESULTS

Plasma ADMA was significantly elevated in CKD patients compared with controls (41.56+/-12.76 microg/mL vs 17.12+/-7.09 microg/mL, P<0.001), and correlated with the left ventricular mass index (LVMI) (r=0.597, P<0.001). During follow-up, 25 patients experienced new CV events and their plasma ADMA level was significantly elevated (48.27+/-13.70 vs 34.91+/-6.38 in CV event-free patients, P<0.001). Cox regression analysis further confirmed that ADMA was an independent risk factor for CVD (HR=1.175, 95%CI[1.070-1.290], P=0.001).

CONCLUSION

Similar to findings in ESRD patients, elevated circulating levels of ADMA may increase the risk of LVH and CV events in pre-dialysis CKD patients.

Relation of flow-mediated dilation to global arterial load: impact of hypertension and additional cardiovascular risk factors

BACKGROUND

Endothelial dysfunction may be related to increased left ventricular (LV) mass due to an association between endothelial dysfunction with increased arterial load. Therefore, we evaluated whether brachial artery flow-mediated dilation (FMD) is related to global arterial load.

METHODS

Pulse pressure/stroke index (PP/SVi, global arterial stiffness, prognostically validated), stroke volume/PP (SV/PP, global arterial compliance), and % of the predicted SV/PP by heart rate, age and body weight (confounder-adjusted global compliance, prognostically validated) were used as LV geometry-related indices of global arterial load.

RESULTS

Compared to normotensive participants (NT, n = 50), those with hypertension (HTN, n = 51) had lower FMD (8.3% ± 5.4 vs. 12.8% ± 6.5), higher PP/SVi (1.24 ± 0.34 vs. 1.04 ± 0.28 mmHg m(2)/ml), higher LV mass and higher relative wall thickness (all p < 0.01); in contrast, SV/PP and % of predicted SV/PP did not differ between NT and HTN (all p>0.1). Impaired FMD was 3-4-fold more prevalent than LV hypertrophy or increased arterial load both in NT and in HTN. Within NT and HTN separately, PP/SVi, SV/PP and % of predicted SV/PP were comparable among tertiles of FMD. Only in NT, lower FMD was associated with higher peak exercise systolic BP (p < 0.05). In multivariable regression models, FMD was not associated with indices of arterial load independently (all p > 0.1).

CONCLUSIONS

In young-to-middle-age subjects with cardiovascular risk factors, impaired FMD is more prevalent than traditional preclinical manifestation of cardiovascular disease, and may exist independent to increased arterial load. Thus, endothelial dysfunction assessment may refine cardiovascular risk profile and risk-reduction strategies based on detection of traditional target organ damage.

Impaired flow-mediated vasodilatation is associated with increased left ventricular mass in a multiethnic population. The Northern Manhattan Study

BACKGROUND

Increased left ventricular (LV) mass and endothelial dysfunction are important risk factors for cardiovascular mortality and morbidity. However, it is not clear whether endothelial dysfunction is associated with increased LV mass. We tested the hypothesis that impaired flow-mediated vasodilatation (FMD) is associated with increased LV mass in a population-based multiethnic cohort.

METHODS

As a part of the Northern Manhattan Study (NOMAS), we performed two-dimensional echocardiography and FMD assessment during reactive hyperemia by high-resolution ultrasonography in 867 stroke-free community participants. LV mass was calculated according to an established method. LV hypertrophy was defined as the 90th percentile of sex-specific LV mass indexed for body surface area among normal subjects. Multivariable models were used to test the association of FMD with LV mass.

RESULTS

In multiple linear regression analysis adjusting for age, sex, body mass index, systolic blood pressure, antihypertensive medications, low-density lipoprotein cholesterol, diabetes, smoking, hematocrit, and race-ethnicity, FMD was inversely associated with LV mass (beta = -1.21 +/- 0.56, P = 0.03). The association persisted after further adjustment for any component of blood pressure (systolic, mean, and pulse pressure). In univariate logistic regression analysis, each 1% decrease in FMD was associated with an 8% higher risk of LV hypertrophy (odds ratio 1.08, 95% confidence interval 1.03-1.13 per each FMD point P < 0.01).

CONCLUSIONS

Impaired FMD is associated with LV mass, independent of other factors associated with increased LV mass. Endothelial dysfunction might be a potential risk factor for LV hypertrophy.

Endothelial dysfunction is associated with left ventricular mass (assessed using MRI) in an adult population (MESA)

Brachial flow-mediated dilation (FMD) is a measure of endothelial nitric oxide bioavailability. Endothelial nitric oxide controls vascular tone and is likely to modify the ventricular muscle coupling mechanism. The association between left ventricular mass and FMD is not well understood. We assessed the association between left ventricular mass index (LVMI) and FMD in participants of the Multi-Ethnic Study of Atherosclerosis (MESA). MESA is a population-based study of 6814 adults free of clinical cardiovascular disease at baseline who were recruited from six US clinics. LVMI (left ventricular mass per body surface area) and FMD were measured in 2447 subjects. Linear regression analysis was used to evaluate the association. The subjects had a mean age of 61.2±9.9 years, 51.2% females with 34.3% Caucasians, 21.6% Chinese, 19.4% African Americans and 24.7% Hispanics. The mean body mass index (BMI) was 27.4±4.8 kg m⁻², 9.4% had diabetes, 11% were current smokers and 38% hypertensives. The mean±s.d. LVMI was 78.1±15.9 g m⁻² and mean±s.d. FMD was 4.4%±2.8%. In univariate analysis, LVMI was inversely correlated with FMD (r= -0.20, P<0.0001). In the multivariable analysis, LVMI was associated with FMD (β coefficient (se) = -0.50 (0.11), P<0.001 (0.5 g m⁻² reduction in LVMI per 1% increase in FMD)) after adjusting for age, gender, race/ethnicity, systolic blood pressure, diabetes mellitus, smoking, weight, statin use, antihypertensive medication use, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol. The association between brachial flow mediated dilation and LVMI maybe independent of traditional CV risk factors in population based adults.

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

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

High-Density Lipoprotein Cholesterol and Left Ventricular Mass Index in Peritoneal Dialysis

Objective

The prevalence of left ventricular hypertrophy (LVH) reaches 75% in patients with end-stage renal disease. In patients on peritoneal dialysis (PD), some factors, such as hypertension, volume overload, serum albumin, and residual renal function, have been reported to be related to LVH. Dyslipidemia often occurs in PD but it remains unclear whether dyslipidemia is related to LVH. We investigated the relationship between clinical parameters, including lipid profile, and left ventricular mass index (LVMI).

Methods

In this cross-sectional study, 34 patients undergoing PD for more than 1 year without combined therapy with hemodialysis were included. We recorded the patients’ clinical data and related those parameters with LVMI as evaluated by echocardiography.

Results

The patients included 23 males and 11 females (age 62.2 ± 12.1 years, duration on PD 31.6 ± 15.6 months). Mean LVMI was 142 ± 37 g/m2. In univariate analysis, urine volume ( r = -0.493, p = 0.003), total cholesterol ( r = -0.418, p = 0.01), high-density lipoprotein cholesterol (HDL-C; r = -0.374, p = 0.02), and human atrial natriuretic peptide (hANP; r = 0.600, p < 0.001) significantly correlated with LVMI. Stepwise multiple regression analysis showed that hANP (β= 0.524, p = 0.001) and HDL-C (β= -0.422, p = 0.007) were independently associated with LVMI ( r2 = 0.32).

Conclusion

Strict volume control and salt restriction is essential for prevention of LVH. The role of HDL-C in the development of LVH in PD patients remains to be determined.

Plasma B-type natriuretic peptide level is associated with left ventricular hypertrophy among obstructive sleep apnoea patients

OBJECTIVES

To examine whether increased plasma levels of B-type natriuretic peptide (BNP) are associated with cardiac structural and functional abnormalities in obstructive sleep apnoea (OSA) patients, taking into consideration the confounding effect of obesity.

MEASUREMENTS

In a cross-sectional study, polysomnography, echocardiography and the measurement of the serum levels of BNP were performed in 235 consecutive subjects (age 52 +/- 14 years) visiting our sleep clinic. Left ventricular hypertrophy (LVH) [left ventricular mass index (LVMI) > or = 125 g/m in men, and > or = 110 g/m in women] and cardiac diastolic function (E/A ratio) were determined by echocardiography.

RESULTS

The LVMI, prevalence rate of LVH and body mass index (BMI) were higher, and the E/A ratio lower in the subjects with severe OSA (apnoea-hypopnoea index > or = 30/h, n = 146, LVH 80%) than in those with mild to moderate OSA (n = 89, LVH 35%; P < 0.01), although plasma BNP levels were similar in the two groups. Although the log-transformed plasma BNP level showed a negative correlation with BMI, the results of binary logistic regression analysis demonstrated that the quintile value of BNP was an independent significant variable for the identification of LVH (adjusted odds ratio in quintile 5 = 4.01, 95% confidence interval 1.18-13.70, P < 0.01), even after adjusting for obesity and other risk factors.

CONCLUSION

An increased likelihood of cardiac structural and functional abnormalities was observed with increasing severity of OSA. Increased plasma levels of BNP do seem to reflect an increased likelihood of LVH in patients with severe OSA.

Diastolic heart failure: mechanisms and controversies

Epidemiological and experimental studies have documented both the rising burden of diastolic heart failure (DHF) and several mechanisms that distinguish this disease from systolic heart failure (SHF). Controversies continue to surround the term 'DHF' as well as its existence as a pathophysiological entity distinct from SHF. Approximately half of all patients who present with heart failure have near-normal systolic function and predominately abnormal diastolic function. Recent reports counter the commonly held belief that survival of patients with DHF is better than that of patients with SHF. The challenges associated with managing the DHF phenotype arise from the heterogeneous etiologies of the condition that include aging, diabetes mellitus, hypertension and ischemia. Lack of diastolic distensibility in DHF has been attributed primarily to hypertrophy and fibrosis. Extracellular matrix and cytoskeletal components including matrix metalloproteinases, titin isoforms, and the quality and quantity of collagen are implicated in DHF development. Impaired active relaxation of the contractile apparatus also contributes to DHF. Novel therapeutic targets that address the pathophysiology of this disease are being actively explored, although as yet there are no proven therapies for DHF. New epidemiologic and mechanistic data regarding DHF highlight the urgency with which the scientific community must address this important public health problem.

Gly460Trp alpha-adducin gene polymorphism and endothelial function in untreated hypertensive patients

OBJECTIVES

Endothelium-dependent vasodilatation is impaired in essential hypertension. Besides traditional and emerging cardiovascular risk factors, genetic factors may also promote deleterious alterations of endothelial physiology. The aim of the present study was to investigate the relationship between the 460Trp allele of ADD1 and endothelium-dependent vasodilation in 110 never-treated hypertensive patients.

METHODS

Forearm blood flow (FBF) was measured during intra-arterial infusion of acetylcholine (ACh) and sodium nitroprusside (SNP) at increasing doses. Analysis of endothelium-dependent and endothelium-independent vasodilation was tested according to ADD1 genotype.

RESULTS

The FBF values at the three incremental doses of ACh were 5.22 +/- 0.24 (+76%), 8.64 +/- 0.45 (+193%) and 14.74 +/- 0.71 (+395%) ml/100 ml of tissue per min for Gly460Gly and 4.63 +/- 0.20 (+51%), 6.84 +/- 0.36 (+123%) and 11.22 +/- 3.8 (+269%) ml/100 ml of tissue per min for 460Trp. Thus, ACh-stimulated FBF was significantly reduced in hypertensive subjects carrying the 460Trp allele of ADD1 (P < 0.001). SNP-stimulated FBF was not affected by ADD1.

CONCLUSIONS

The main finding in this study was that in essential hypertensives the 460Trp allele of ADD1 is strongly associated with an impaired endothelium-dependent vasodilation, a powerful predictor of cardiovascular risk.

High-density lipoprotein cholesterol and insulin resistance are independent and additive markers of left ventricular hypertrophy in essential hypertension

We examined whether plasma high-density lipoprotein-cholesterol (HDL-C) levels and glucose metabolism parameters are independent or additive predictors of left ventricular hypertrophy (LVH) in patients with untreated essential hypertension. The study group consisted of 41 Japanese patients with untreated essential hypertension and LVH (left ventricular mass index [LVMI] >125 g/m2; age 58+/-6 years, mean+/-SD), and the control group consisted of 39 age-matched patients with untreated essential hypertension without LVH (LVMI <or=125 g/m2; age 58+/-7 years). The following metabolic parameters were higher in the group with LVH: fasting plasma glucose (FPG) (p<0.01), fasting insulin concentration (F-IRI) (p<0.0001), and homeostasis model assessment (HOMA)-index (p<0.0001). Among the laboratory parameters investigated, plasma HDL-C levels were lower (p<0.0001), and triglyceride and uric acid levels were higher in the group with LVH (p<0.05 for both). The nighttime systolic and diastolic ambulatory blood pressure (ABP) (p<0.0001, p<0.01, respectively) and nighttime heart rate (p<0.01) were higher in patients with LVH. Multivariate logistic analysis identified HDL-C (odds ratio [OR]=0.92, 95% confidence interval [CI]=0.87-0.98, p<0.05), HOMA-index (OR=3.83, 95% CI=1.28-11.5, p<0.05) and nighttime systolic ambulatory blood pressure (ABP) (OR=1.06, 95% CI=1.00-1.13, p<0.05) as independent significant risk factors for LVH. Our findings suggest that HDL-C, HOMA-index and nighttime systolic ABP are independent predictors for the presence of LVH in Japanese patients with essential hypertension.

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

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

Endothelial dysfunction and the kidney: emerging risk factors for renal insufficiency and cardiovascular outcomes in essential hypertension

Renal insufficiency in essential hypertension represents the expression of a medium- and small-size arteriolopathy characterized by intimal hyperplasia, hyalinosis, and smooth muscle cell hypertrophy (nephroangiosclerosis). Because in animal models endothelial dysfunction plays a role in this alteration, nephroangiosclerosis and the attendant renal insufficiency may be the expression of a systemic dysfunction of vascular endothelium. Endothelial function in the kidney vasculature of hypertensive individuals has been investigated little because studies on the hemodynamic response of the kidney to nitric oxide activation and blockade are laborious to perform. There is no direct proof that endothelial dysfunction in the forearm or in the coronary circulation is paralleled by a similar hemodynamic dysfunction in the kidney. A recent study in a large population of patients with essential hypertension showed that, independent of other risk factors, the GFR in these patients is strongly related to the forearm blood flow response to acetyl choline (an established test of endothelial function). Furthermore, in this study, C-reactive protein was inversely related to the GFR and with the vasodilatory response to acetyl choline, pointing to inflammation as a likely mechanism to explain the association between endothelial dysfunction and impaired renal function in essential hypertension. A dysfunctional endothelium may represent a critical link accounting for the risk for both renal impairment and cardiovascular complications in essential hypertension.

The vascular endothelium in hypertension

The vascular endothelium plays a fundamental role in the basal and dynamic regulation of the circulation. Thus, it has a crucial role in the pathogenesis of hypertension. A spectrum of vasoactive substances is synthesised in the endothelium; of these, nitric oxide (NO), prostacyclin (PGI2) and endothelin (ET)-1 are the most important. There is a continuous basal release of NO determining the tone of peripheral blood vessels. Systemic inhibition of NO synthesis or scavenging of NO through oxidative stress causes an increase in arterial blood pressure. Also, the renin-angiotensin-aldosterone system has a major role in hypertension as it has a direct vasoconstrictor effect and important interactions with oxygen free radicals and NO. Prostacyclin, in contrast to NO, does not contribute to the maintenance of basal vascular tone of conduit arteries, but its effect on platelets is most important. ET acts as the natural counterpart to endothelium-derived NO and has an arterial blood pressure-raising effect in man. Anti-hypertensive therapy lowers blood pressure and may influence these different mediators, thus influencing endothelial function. In summary, due to its position between the blood pressure and smooth muscle cells responsible for peripheral resistance, the endothelium is thought to be both victim and offender in arterial hypertension. The delicate balance of endothelium-derived factors is disturbed in hypertension. Specific anti-hypertensive and anti-oxidant treatment is able to restore this balance.

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

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

Relations of left ventricular mass and systolic function to endothelial function and coronary flow reserve in healthy, new discovered hypertensive subjects

Left ventricular hypertrophy (LVH) is prognostically relevant, associated with major cardiovascular risk factors and with atherosclerosis. However, whether LVH is independently associated with impaired coronary flow reserve (CFR) and with endothelial dysfunction is disputed. We assessed the relationship of LV mass and systolic function to CFR and endothelial function in new discovered never treated subjects with essential arterial hypertension, but without coronary artery disease or microalbuminuria. LVH, ejection fraction (EF) and stress-corrected midwall shortening (MWS, a measure of myocardial contractility) were assessed by echocardiography. CFR was assessed by single-photon emission computed tomography and dipyridamole infusion. Endothelial function was evaluated by assessing 1-min postischaemic flow-mediated dilatation of the brachial artery (FMD); nitroglycerine-mediated dilatation (NMD) of the same brachial artery was used as measure of nonendothelium-dependent vasodilatation. In approximately 1 year, we enrolled 21 subjects who met stringent inclusion criteria (47+/-10 years old, 26.6+/-2.8 kg/m2, 78% men). Five patients showed LVH. Multivariate analyses showed a significant negative correlation of LV mass index with FMD (beta=-0.61, P<0.05) but not with NMD, neither with CFR. Stress-corrected MWS showed independent correlation with CFR (beta=0.51, P<0.05). Thus, in clinically healthy, new discovered hypertensive subjects, never treated and mostly in the early stage of arterial hypertension, LVH can be associated with endothelial dysfunction while maximal dipyridamole- dependent CFR may be preserved; nevertheless, a cardiac phenotype presenting with tendency to impaired myocardial contractility, assessed by stress-corrected MWS, showed association with lower CFR in the early stage of arterial hypertension.

From Left Ventricular Hypertrophy to Congestive Heart Failure: Management of Hypertensive Heart Disease

Other than age, left ventricular hypertrophy (LVH) is the most potent predictor of adverse cardiovascular outcomes in the hypertensive population, and is an independent risk factor for coronary heart disease, sudden death, heart failure and stroke. Although directly related to systolic blood pressure, other factors including age, sex, race, body mass index and stimulation of the renin-angiotensin-aldosterone and sympathetic nervous systems play an important role in the pathogenesis of LVH. LVH involves changes in myocardial tissue architecture consisting of perivascular and myocardial fibrosis and medial thickening of intramyocardial coronary arteries, in addition to myocyte hypertrophy. The physiologic alterations which occur as a result of these anatomical changes include disturbances of myocardial blood flow, the development of an arrhythmogenic myocardial substrate and diastolic dysfunction. The latter is directly related to the degree of myocardial fibrosis and is the hemodynamic hallmark of hypertensive heart disease. When diastolic dysfunction is present, left ventricular end-diastolic pressure increases out-of-proportion to volume and may be elevated at rest or with exertion leading to clinical heart failure. At least one third of heart failure patients in the United States can be considered to have heart failure related to diastolic dysfunction. Compared to heart failure patients with systolic dysfunction, diastolic heart failure patients are more likely to be older, female, and to be hypertensive at the time of presentation. Although it has been assumed that LVH may lead to systolic dysfunction, evidence is lacking that LVH resulting from hypertension is a major risk factor for systolic heart failure independent of coronary artery disease. Treatment of hypertension greatly attenuates the development of LVH and significantly decreases the incidence of heart failure. In patients with established LVH, regression is both possible and desirable and results in a significant reduction in adverse clinical endpoints.

Endothelial dysfunction: a comprehensive appraisal

The endothelium is a thin monocelular layer that covers all the inner surface of the blood vessels, separating the circulating blood from the tissues. It is not an inactive organ, quite the opposite. It works as a receptor-efector organ and responds to each physical or chemical stimulus with the release of the correct substance with which it may maintain vasomotor balance and vascular-tissue homeostasis. It has the property of producing, independently, both agonistic and antagonistic substances that help to keep homeostasis and its function is not only autocrine, but also paracrine and endocrine. In this way it modulates the vascular smooth muscle cells producing relaxation or contraction, and therefore vasodilatation or vasoconstriction. The endothelium regulating homeostasis by controlling the production of prothrombotic and antithrombotic components, and fibrynolitics and antifibrynolitics. Also intervenes in cell proliferation and migration, in leukocyte adhesion and activation and in immunological and inflammatory processes. Cardiovascular risk factors cause oxidative stress that alters the endothelial cells capacity and leads to the so called endothelial "dysfunction" reducing its capacity to maintain homeostasis and leads to the development of pathological inflammatory processes and vascular disease.

There are different techniques to evaluate the endothelium functional capacity, that depend on the amount of NO produced and the vasodilatation effect. The percentage of vasodilatation with respect to the basal value represents the endothelial functional capacity. Taking into account that shear stress is one of the most important stimulants for the synthesis and release of NO, the non-invasive technique most often used is the transient flow-modulate "endothelium-dependent" post-ischemic vasodilatation, performed on conductance arteries such as the brachial, radial or femoral arteries. This vasodilatation is compared with the vasodilatation produced by drugs that are NO donors, such as nitroglycerine, called "endothelium independent". The vasodilatation is quantified by measuring the arterial diameter with high resolution ultrasonography. Laser-Doppler techniques are now starting to be used that also consider tissue perfusion.

There is so much proof about endothelial dysfunction that it is reasonable to believe that there is diagnostic and prognostic value in its evaluation for the late outcome. There is no doubt that endothelial dysfunction contributes to the initiation and progression of atherosclerotic disease and could be considered an independent vascular risk factor. Although prolonged randomized clinical trials are needed for unequivocal evidence, the data already obtained allows the methods of evaluation of endothelial dysfunction to be considered useful in clinical practice and have overcome the experimental step, being non-invasive increases its value making it use full for follow-up of the progression of the disease and the effects of different treatments.

Asymmetric dimethylarginine: a cardiovascular risk factor and a uremic toxin coming of age?

The idea that asymmetric dimethylarginine (ADMA) accumulation may be a cardiovascular risk factor in patients with end-stage renal disease was advanced by Vallance in 1992. During the last decade, the relationship between ADMA and adverse cardiovascular events, including death, in dialysis patients has been investigated thoroughly. Several studies have shown that, independently of other risk factors, ADMA is strongly associated with intima-media thickness of the carotid artery and left ventricular mass, particularly concentric left ventricular hypertrophy. Furthermore, cohort studies in both the general population and the dialysis population showed a strong and independent link between ADMA, all-cause mortality, and cardiovascular events. Circumstantial evidence indicates that norepinephrine and ADMA may be in the same causal pathway leading to cardiovascular complications in patients with end-stage renal disease. Several lines of evidence show that high ADMA levels may exert toxic effects in various cell types. High ADMA levels have been associated with alterations in the regulation of cerebral blood flow and neural function, with insulin resistance, thyroid dysfunction, and alterations in bone homeostasis, fertility, and erectile function. The clinical significance of decreasing plasma ADMA concentrations, if any, is unknown. Well-designed and carefully conducted studies are needed to further clarify the role of ADMA in the pathophysiological states of renal disease and explore possible treatment options to improve the prognosis of patients with elevated ADMA levels. ADMA may enable us to predict risk and follow up the course of renal diseases.

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

AIMS

To investigate the additive prognostic impact of both forearm endothelial dysfunction and left ventricular mass (LVM) for future cardiovascular events.

METHODS AND RESULTS

We enrolled 324 Caucasian, never treated, hypertensive outpatients. Endothelial function, by intra-arterial infusion of acetylcholine (ACh), and echocardiographic LVM were investigated. Patients were divided into tertiles on the basis of their increase in ACh-stimulated forearm blood flow (FBF) and LVM indexed by body surface area (LVMI). Cardiovascular events assessed were: fatal and non-fatal myocardial infarction, fatal and non-fatal stroke, transient cerebral ischaemic attack, unstable angina, coronary revascularization procedures, and symptomatic aorto-iliac occlusive disease. During a mean follow-up of 45.2+/-23.6 months, there were 47 new cardiovascular events (3.8 events/100 patient-years). The event rate was 6.8, 2.8, and 1.6% in the tertiles of ACh-stimulated FBF (log-rank test, P=0.0009), and 1.4, 3.4, and 6.6% in the tertiles of LVMI (log-rank test, P=0.0002), respectively. Besides, a significant interaction was documented between FBF and LVMI. In fact, the cardiovascular risk increases up to 11.4% in patients with low FBF and high LVMI.

CONCLUSION

For the first time, we demonstrate that the co-existence of LVH and endothelial dysfunction in hypertensive patients increases significantly the risk of subsequent cardiovascular events.

Protection of endothelial function

The vascular endothelium synthesizes and releases a spectrum of vasoactive substances and therefore plays a fundamental role in the basal and dynamic regulation of the circulation. Nitric oxide (NO)--originally described as endothelium-derived relaxing factor--is released from endothelial cells in response to shear stress produced by blood flow, and in response to activation of a variety of receptors. After diffusion from endothelial to vascular smooth muscle cells, NO increases intracellular cyclic guanosine-monophosphat concentrations by activation of the enzyme guanylate cyclase leading to relaxation of the smooth muscle cells. NO has also antithrombogenic, antiproliferative, leukocyte-adhesion inhibiting effects, and influences myocardial contractility. Endothelium-derived NO-mediated vascular relaxation is impaired in spontaneously hypertensive animals. NO decomposition by free oxygen radicals is a major mechanism of impaired NO bioavailability. The resulting imbalance of endothelium-derived relaxing and contracting substances disturbs the nor- mal function of the vascular endothelium. Endothelin acts as the natural counterpart to endothelium-derived NO. In man, besides its effect of increasing arterial blood pressure, ET-1 induces vascular and myocardial hypertrophy, which are independent risk factors for cardiovascular morbidity and mortality. Current therapeutic strategies concentrate mainly on lowering of low-density lipoprotein cholesterol and an impressive reduction in the risk for cardiovascular morbidity and mortality has been achieved. Inflammatory mechanisms play an important role in vascular disease and inflammatory plasma markers correlate with prognosis. Novel therapeutic strategies specifically targeting inflammation thus bear great potential for the prevention and treatment of atherosclerotic vascular disease.

Effects of exercise, diet and weight loss on high blood pressure

High blood pressure (BP) is a major health problem in the US, affecting more than 50 million people. Although high BP is among the most common reasons for outpatient visits, BP control is often inadequate. It is well established that BP can be lowered pharmacologically in hypertensive individuals; however, anti-hypertensive medications are not effective for everyone, and may be costly and result in adverse effects that impair quality of life and reduce adherence. Moreover, abnormalities associated with high BP, such as insulin resistance and hyperlipidaemia, may persist or may even be exacerbated by some anti-hypertensive medications. Consequently, there has been a great deal of interest in the development and application of behavioural interventions in the management of high BP. The main behavioural interventions that are recommended to reduce BP are exercise and the Dietary Approaches to Stop Hypertension (DASH) diet. Weight loss is also recommended for BP reduction in overweight individuals. Exercise alone is associated with reductions of approximately 3.5 and 2.0mm Hg in systolic (SBP) and diastolic blood pressure (DBP), respectively. Patients fed a DASH diet (a diet high in low-fat dairy products and fibre, including fruits and vegetables) had reductions in SBP and DBP of 5.5 and 3.0mm Hg, respectively, compared with those consuming a standard US diet. Reductions of approximately 8.5mm Hg SBP and 6.5mm Hg DBP accompany weight loss of 8 kg. In overweight hypertensive patients, a combined exercise and weight-loss intervention has been shown to decrease SBP and DBP by 12.5 and 7.9 mm Hg, respectively. There is evidence to suggest that these decreases in BP are associated with improvements in left ventricular structure and function, and peripheral vascular health. Both exercise training and weight loss have been shown to decrease left ventricular mass and wall thickness, reduce arterial stiffness and improve endothelial function. These data support the role of behavioural interventions in the treatment of patients with elevations in BP.

Gender influences endothelial-dependent arterial dilatation via arterial size in youth

BACKGROUND

Reduced endothelial-dependent arterial dilatation (EDAD) has been suggested as an early marker of arteriosclerosis, since it has been reported to correlate with known cardiovascular disease (CVD) risk factors. It is unclear, however, whether gender plays a mediating or a moderating role in these relationships. The aim of this study was to evaluate the influence of gender on EDAD in youth at risk for CVD.

METHODS

The sample population of 261 individuals (mean age, 20 yr; SD, 3 yr) consisted of 148 African Americans, 113 European Americans, 133 males, and 128 females, all with a verified family history of CVD (ie, hypertension, myocardial infarction). Anthropometrics, sociometrics, hemodynamics, brachial artery diameter, left ventricular mass, and relative wall thickness were measured and used as independent variables. EDAD (dependent variable) was expressed as percent (%) change of brachial artery diameter to reactive hyperemia induced by pressure cuff occlusion and release. Artery diameters were calculated via an automated border detection system.

RESULTS

Percent EDAD change was inversely related to initial diameter of the brachial artery. Mean percent EDAD change was 14.37% for female subjects compared with 10.48% for male subjects. The gender difference was a function of smaller initial artery size in the female subjects. When initial diameter and gender were considered simultaneously within a multivariate model, the gender effect was eliminated. Although a large prediameter effect remained, the relationship between prediameter and EDAD was greater in female than in male subjects (ie, interaction/moderating effect).

CONCLUSION

The data suggest that the smaller the artery is, the more it will dilate. Further EDAD investigations are needed to predict arteriosclerosis, taking into account of the gender difference in vessel size.

Specific alterations of endothelial signal transduction pathways of porcine epicardial coronary arteries in left ventricular hypertrophy

Coronary endothelial dysfunction in left ventricular hypertrophy (LVH) can reduce myocardial perfusion and result in an impaired global LV function. The objective of this study was to characterize the specific alterations of endothelial signal transduction of coronary arteries in a swine LVH model. Aortic banding was performed 3 cm above the coronary ostia. Vascular reactivity studies were performed to assess the nitric oxide (NO) and the EDHF-mediated relaxations. There was a significant increase in LV/body weight ratio associated with an increased in LV diastolic and end-diastolic pressure and decrease in dP/dT (P < 0.05), with no significant difference in coronary pressures 60 days after pressure-overload LVH. There was a significant decrease in endothelium-dependent relaxations to serotonin (5-HT) and to bradykinin (BK) (P < 0.05 for both) from LVH animals. There was no significant decrease of relaxations in the presence of BK and Nomega-l-arginine (EDHF pathway). Plasma NO(x) levels decreased significantly from 1.8% +/- 0.2% to 1.2% +/- 0.1% (P < 0.05 versus control). Chronic pressure-overload LVH is associated with an endothelial dysfunction involving both Gi and Gq protein-mediated relaxations in coronary arteries as well as the EDHF pathway.

Association of interleukin-6 -174G/C promoter polymorphism with hypertension and left ventricular hypertrophy in dialysis patients

BACKGROUND

Gene polymorphisms of proinflammatory cytokines, such as interleukin-6 (IL-6) and the chemokine receptor CX3CR1, have been found in association with cardiovascular disease in the general population. In dialysis patients, in whom the prevalence of cardiovascular comorbidity is strikingly high, these polymorphisms have not been investigated.

METHODS

The -174G/C polymorphism of the IL-6 gene and the chemokine receptor CX3CR1 polymorphisms 249V/I and 280T/M were examined for their association with cardiovascular abnormalities in a cohort of 161 patients with end-stage renal disease (ESRD) treated by hemodialysis. Arterial blood pressure, electrocardiogram (ECG) ischemic changes, and left ventricular mass index (LVMI) were the parameters examined for the association study. The control group was made up of 169 healthy subjects.

RESULTS

We found that for both IL-6 and chemokine receptor, genotype frequency and allelic distribution in both ESRD patients and controls were comparable. The genetic association study showed that in the whole group of dialysis patients, individuals with GC + CC genotype for the -174G/C polymorphism had a higher diastolic blood pressure (P = 0.008) and LVMI (P = 0.026) than GG homozygotes. The prevalence of left ventricular hypertrophy (LVH) in the former group was 58.6% vs. 39.2% in the latter (P = 0.02). The same analysis limited to diabetic patients in dialysis, showed that the prevalence of LVH in those with CG + CC genotype was 87.5% vs. 36.3% in those with GG genotype (P = 0.02). In diabetic patients, lower levels of serum albumin was found in the GC + CC genotypic group than in GG subjects; 34.63 +/- 5.18 g/L vs. 41.75 +/- 4.79 g/L (P = 0.003).

CONCLUSION

These data demonstrate an association between the IL-6 promoter polymorphism -174G/C and high blood pressure and LVH in hemodialysis patients, especially those with diabetes. The results strengthen the hypothesis that chronic inflammation is a mechanism of cardiovascular damage in dialysis patients and the role played by the IL-6 system in this mechanism.

Pulse pressure and endothelial dysfunction in never-treated hypertensive patients

OBJECTIVES

This study sought to investigate whether pulse pressure (PP) is associated with endothelium-dependent vasodilation in a group of never-treated hypertensives.

BACKGROUND

Pulse pressure represents a well-established independent predictor for cardiovascular morbidity and mortality. Forearm endothelial dysfunction, defined as impaired vasodilating response to acetylcholine (ACh), may be associated with several cardiovascular risk factors. Recently, the prognostic value of coronary and forearm endothelial dysfunction has been demonstrated.

METHODS

All patients underwent measurement of blood pressure (BP) both clinically and in an ambulatory setting. Endothelium-dependent and -independent vasodilation was investigated by strain-gauge plethysmography in 262 hypertensive patients (age 30 to 55 years) during intra-arterial infusion of increasing doses of ACh and sodium nitroprusside.

RESULTS

We observed that systolic BP rather than diastolic BP significantly induces the PP increase. Linear regression analysis revealed a significant inverse correlation between ACh-stimulated forearm blood flow (FBF) and age, body mass index, clinic and monitored systolic BP, and clinic and monitored PP. However, stepwise multivariate analysis showed that monitored PP was the strongest independent predictor of ACh-stimulated FBF, accounting for 33.6% of the variation. After adjustment for other covariates, ACh-stimulated FBF decreases by 8.7% for each mm Hg increment in monitored PP.

CONCLUSIONS

Our data indicate that monitored PP is inversely correlated with ACh-stimulated vasodilation. It is possible to hypothesize that elevation in PP reduces FBF by increasing oxidative stress and reducing production of nitric oxide caused by reduced shear stress. In addition, the present findings demonstrate the accuracy of ambulatory BP as a prognostic predictor of hypertension-associated endothelial dysfunction.

Left ventricular hypertrophy and endothelial dysfunction in chronic hemodialysis patients

BACKGROUND

Endothelial dysfunction (ED), which is a risk factor for atherosclerosis, has been reported recently in chronic hemodialysis (CHD) patients. In this study, we aim to investigate the association of ED and presence of left ventricular hypertrophy (LVH) in CHD patients.

METHODS

One hundred four CHD patients (47 men, 57 women; mean age, 45 +/- 12 years) and 49 age- and sex-matched controls were included. Mean time on dialysis therapy was 62 months. Echocardiographic examination and flow-mediated endothelium-dependent (EDD) and endothelium-independent dilatation (EID) of the brachial artery, measured by high-resolution ultrasonography, a noninvasive method for assessing endothelial function, were performed on a nondialysis day.

RESULTS

LVH was detected in 72 CHD patients (69%). Patients with LVH had a lower EDD (9.3% +/- 6.1% versus 12.1% +/- 8.3%; P = 0.06), but the difference was not significant. Mean EID was significantly lower in CHD patients with LVH (13.6% +/- 7.6% versus 18.6% +/- 9.8%; P = 0.008). Left ventricular mass index (LVMI) correlated with both EDD (r = -0.22; P = 0.03) and EID (r = -0.32; P = 0.002). Patients with LVH had a greater rate of hypertension (35 of 72 versus 7 of 32 patients; P = 0.02) and lower hemoglobin levels (11.0 +/- 1.8 versus 11.8 +/- 1.6 g/dL [110 +/- 18 versus 118 +/- 16 g/L]; P = 0.05). CHD patients had a lower EDD (10.2% +/- 6.9% versus 20.9% +/- 7.6%; P < 0.001) and EID (15.0% +/- 8.5% versus 27.8% +/- 8.5%; P < 0.001) compared with controls. In linear regression analysis for predicting LVMI, presence of hypertension, hemoglobin level, and EID, but not EDD, were found to be independent variables.

CONCLUSION

EID, which may reflect decreased elasticity of arteries, contributes to the development of LVH in CHD patients, in addition to hypertension and anemia.

Hypertension, left ventricular hypertrophy, and sudden death

Left ventricular hypertrophy (LVH), a form of end-organ damage in hypertension, is associated with increased incidence of sudden cardiac death (SCD). This review explores the possible mechanisms behind this phenomenon. SCD in LVH could be thrombotic/ischemic or arrhythmic (eg, myocardial ischemia, even in the absence of significant coronary artery disease, may be one important factor). Abnormalities of flow-mediated dilatation, endothelial function, and a hypercoagulable state are well-observed abnormalities in association with hypertension and LVH, although their precise contributory role is as yet undefined in the pathogenesis of sudden death. Electrophysiologic abnormalities are also well documented in LVH, and such patients are more predisposed to arrhythmias. In the past decade, many studies have investigated the regression of LVH, and recent studies are addressing whether the latter translates into a prognostic benefit.