Atherosclerosis progression affects the relationship between endothelial function and aortic stiffness

Effects of heart rate reduction with ivabradine on vascular stiffness and endothelial function in chronic stable coronary artery disease

INTRODUCTION

Epidemiological and clinical studies have shown a relevant association between heart rate and cardiovascular mortality. Experimental studies identified vascular effects of heart rate reduction with the If channel inhibitor ivabradine. Therefore, the effects of heart rate reduction on endothelial function and indices of arterial stiffness were examined in patients with stable coronary artery disease in a prospective, placebo-controlled clinical crossover study.

METHODS AND RESULTS

Twenty-three patients (18 men and 5 women) with a resting heart rate (HR) of at least 70 beats per minute (bpm) and stable coronary artery disease were enrolled in this study. In a cross-over design, all patients were treated with ivabradine (Iva, 7.5 mg b.i.d.) and placebo for 6 months each. Iva reduced heart rate by 11.4 bpm (Iva 58.8 ± 8.2 bpm vs. placebo 70.2 ± 8.3 bpm, P < 0.0001). Augmentation index (AIx75), carotid-femoral pulse wave velocity (cfPWV) and central aortic blood pressure were measured using applanation tonometry (SphygmoCor). HRR by Iva increased AIx75 by 12.4% (Iva 24.3 ± 10.5% vs. placebo 21.3 ± 10.1%, P < 0.05) and reduced cfPWV by 14.1% (Iva 6.3 ± 1.7 m/s vs. placebo 7.3 ± 1.4 m/s, P < 0.01). Iva increased mean central blood pressure by 7.8% (Iva 107.5 ± 15.4 mmHg vs. placebo 99.1 ± 12.2 mmHg, P < 0.001). Endothelial function was determined measuring the flow-mediated vasodilation (FMD) of the brachial artery. HRR by Iva increased FMD by 18.5% (Iva 7.3 ± 2.2% vs. placebo 6.0 ± 2.0%, P < 0.001). Aortic distensibility was characterized by MRI. HRR by Iva increased aortic distensibility by 33.3% (Iva 0.003 ± 0.001/mmHg vs. placebo 0.002 ± 0.010/mmHg, P < 0.01) and circumferential cyclic strain by 37.1% (Iva 0.062 ± 0.027 vs. placebo 0.039 ± 0.018, P < 0.0001).

CONCLUSION

Heart rate reduction with Iva increased endothelium-dependent vasodilation and reduced arterial stiffness in patients with stable CAD. These findings corroborate and expand the results collected in experimental studies and indicate the importance of heart rate as a determinant of vascular function.

Virtual Histology to Evaluate Mechanisms of Pulmonary Artery Lumen Enlargement in Response to Balloon Pulmonary Angioplasty in Chronic Thromboembolic Pulmonary Hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) results from an obstruction of pulmonary arteries (PAs) by organized thrombi. The stenosed PAs are targeted during balloon pulmonary angioplasty (BPA). We aimed to evaluate the mechanism of BPA in inoperable patients with CTEPH. We analyzed stenosed PAs with intravascular grey-scale ultrasound (IVUS) to determine the cross-sectional area (CSA) of arterial lumen and of organized thrombi. The composition of organized thrombi was assessed using virtual histology. We distinguished two mechanisms of BPA: Type A with dominant vessel stretching, and type B with dominant thrombus compression. PAs were assessed before (n = 159) and after (n = 98) BPA in 20 consecutive patients. Organized thrombi were composed of dark-green (57.1 (48.0–64.0)%), light-green (34.0 (21.4–46.4)%), red (6.4 (2.9–11.7)%;) and white (0.2 (0.0–0.9)%) components. The mechanism type depended on vessel diameter (OR = 1.09(1.01–1.17); p = 0.03). In type B mechanism, decrease in the amount of light-green component positively correlated with an increase in lumen area after BPA (r = 0.50; p = 0.001). The mechanism of BPA depends on the diameter of the vessel. Dilation of more proximal PAs depends mainly on stretching of the vessel wall while dilation of smaller PAs depends on compression of the organized thrombi. The composition of the organized thrombi contributes to the effect of BPA.

Matrix stiffening induces endothelial dysfunction via the TRPV4/microRNA-6740/endothelin-1 mechanotransduction pathway

Vascular stiffening is associated with the prognosis of cardiovascular disease (CVD). Endothelial dysfunction, as shown by reduced vasodilation and increased vasoconstriction, not only affects vascular tone, but also accelerates the progression of CVD. However, the precise effect of vascular stiffening on endothelial function and its mechanism is unclear and a possible underlying has not been determined. In this study, we found that increasing substrate stiffness promoted endothelin-1 (ET-1) expression and inhibited endothelial nitric oxide synthase expression in human umbilical vein endothelial cells. Additionally, miR-6740-5p was identified as a stiffness-sensitive microRNA, which was downregulated by a stiff substrate, resulting in increased ET-1 expression. Furthermore, we found that substrate stiffening reduced the expression and activity of the calcium channel TRPV4, which subsequently enhanced ET-1 expression by inhibiting miR-6740-5p. Finally, analysis of clinical plasma samples showed that plasma miR-6740-5p levels in patients with carotid atherosclerosis were significantly lower than those in healthy people. Taken together, our findings show a novel mechanically regulated TRPV4/miR-6740/ET-1 signaling axis by which substrate stiffness affects endothelial function. Our findings indicate that vascular stiffening induces endothelial dysfunction, thereby accelerating progression of CVD. Furthermore, this study indicates that endothelial dysfunction induced by improper biophysical cues from cardiovascular implants may be an important reason for complications arising from the use of cardiovascular implants. STATEMENT OF SIGNIFICANCE: Cardiovascular disease is the leading cause of morbidity and mortality worldwide. The incidence of cardiovascular disease is accompanied by increased vascular stiffness. Our work indicated that increased vascular stiffness accelerates the development of cardiovascular disease by inducing endothelial dysfunction, which is a key contributor to the pathogenesis of cardiovascular disease. In addition, we identified a novel underlying molecular pathophysiological mechanism by which increased stiffness induce endothelial dysfunction. Our work could help determine the pathogenesis of cardiovascular disease induced by biomechanical factors.

Prognostic role of traditional cardiovascular risk factors in patients with idiopathic pulmonary arterial hypertension

INTRODUCTION

Metabolic alterations have been recently associated with onset and progression of idiopathic pulmonary arterial hypertension (IPAH). We aimed to determine the prevalence and prognostic role of cardiovascular risk factors in patients with IPAH.

MATERIAL AND METHODS

Between February 2009 and January 2015 we recruited consecutive IPAH patients. Clinical assessment included medical history, fasting glucose, lipid profile, N-terminal pro-brain natriuretic peptide concentration, 6-minute walk test distance, WHO functional class and hemodynamic evaluation. Patients' risk was estimated based on the Swedish PAH Register grading system.

RESULTS

The study group included 61 IPAH patients, and the control group included 2413 Polish residents. When compared to the general population, IPAH patients had lower low-density lipoprotein cholesterol (LDL-C) and a higher triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio. Female patients were characterized by elevated glucose level, higher prevalence of diabetes and lower HDL-C than controls. PAH severity grade correlated positively with age and TG/HDL-C ratio (R = 0.29, p = 0.02) and inversely with LDL-C (R = -0.28, p = 0.03) and HDL-C (R = -0.39, p = 0.02) concentrations. After a follow-up of 48 (23-79) months we recorded 28 deaths in the IPAH group. In the regression analysis lower LDL-C (p = 0.002) and HDL-C (p = 0.0002) levels, and higher TG/HDL-C ratio (p = 0.003) and glucose level (p = 0.003) were associated with all-cause mortality after adjustment for age, sex or PAH severity grade.

CONCLUSIONS

Patients with IPAH are characterized by an altered profile of lipid and glucose metabolism. Lowered levels of LDL-C and HDL-C and increased TG/HDL-C ratio correlate with disease severity and together with elevated plasma glucose level predict poor survival in IPAH.

Influence of Body Composition on Arterial Stiffness in Middle-Aged Adults: Healthy UAL Cross-Sectional Study

Background and objectives: Several anthropometric and body composition parameters have been linked to arterial stiffness (AS) as a biomarker of cardiovascular disease. However, little is known about which of these closely related factors is more strongly associated with AS. The aim of the present study was to analyze the relationship of different anthropometric and body composition parameters with AS in middle-aged adults. Materials and Methods: This cross-sectional study included 186 middle-aged participants (85 women, 101 men; age = 42.8 ± 12.6 years) evaluated as part of the Healthy UAL study, a population study conducted at the University of Almería with the main purpose of analyzing the etiology and risk factors associated with cardio-metabolic diseases. Anthropometric measures included neck, waist, and hip circumferences, as well as the waist-to-height ratio (WHtr). Bioimpedance-derived parameters included fat-free mass index (FFMI), fat mass index (FMI), and percent of body fat (%BF). AS was measured by pulse wave velocity (PWV). The relationships of interest were examined through stepwise regression analyses in which age and sex were also introduced as potential confounders. Results: Neck circumference (in the anthropometric model; R²: 0.889; β: age = 0.855, neck = 0.204) and FFMI (in the bio-impedance model; R²: 0.891; β: age = 0.906, FFMI = 0.199) emerged as significant cross-sectional predictors of AS. When all parameters were included together (both anthropometry and bio-impedance), both neck circumference and FFMI appeared again as being significantly associated with AS (R²: 0.894; β: age = 0.882, FFMI = 0.126, neck = 0.093). Conclusion: It was concluded that FFMI and neck circumference are correlated with AS regardless of potential confounders and other anthropometric and bioimpedance-derived parameters in middle-aged adults.

Pulmonary Artery Elastic Properties After Balloon Pulmonary Angioplasty in Patients With Inoperable Chronic Thromboembolic Pulmonary Hypertension

BACKGROUND

A significant proportion of the right ventricular afterload is determined by the elastic properties of the pulmonary artery (PA). We aimed to assess the effect of balloon pulmonary angioplasty (BPA) on PA elastic properties in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH).

METHODS

We enrolled adult patients with CTEPH treated with BPA and controls without PH. Total PA compliance (CPa) was calculated as stroke volume/PA pulse pressure. PA distensibility (DC) and compliance (CC) coefficients were assessed by intravascular ultrasound to denote local elastic properties of the treated PA segments.

RESULTS

We performed 103 BPA sessions in 17 patients with CTEPH (5 men [29%], aged 66 [64 to 73] years) who were followed for 6 (5 to 7) months after the last BPA. The median time between BPA sessions was 39 (28 to 52) days. The CPa, CC, and DC were lower in patients with CTEPH than in controls without PH (n = 10). Complete BPA treatment led to increase of CPa from 1.02 (0.70 to 1.39) to 2.08 (1.49 to 2.39) mL/mm Hg (P < 0.001) at the 6-month follow up, and this increase was in proportion to a decrease in pulmonary vascular resistance (PVR) (R² = 0.74; P = 0.001). CPa increased immediately after BPA session by 0.13 (-0.05; 0.33) mL/mm Hg (P = 0.001) and remained unchanged until the next BPA session. CC and DC exhibited no immediate change after catheter balloon inflation (Δ=0 [-0.03; 0.02] mm²/mm Hg, P = 0.52, and Δ = 0 [-0.13; 0.13] %/mm Hg, P = 0.91, respectively) and remained unchanged at the 6-month follow-up.

CONCLUSIONS

BPA improved total CPa in proportion to a decrease in PVR despite no improvement in local elastic properties of the treated PA segments.

Atherosclerosis of brachiocephalic arteries and arterial stiffness in patients with breast cancer

Cardiovascular toxicity is one of the important problems of clinical oncology. Atherosclerosis progression was demonstrated in patients with cancer and chemotherapy.Te aim - to evaluate the vascular wall characteristics and to determine the predictors of AS of brachiocephalic arteries progression during anticancer therapy in patients with breast cancer.

METHODS

Te study involved 43 patients with newly diagnosed breast cancer (BC) (II-III stage) with overexpression of HER2; median age 50 (40;57) years. All patients underwent neoadjuvant drug therapy with antracyclines, taxanes and trastuzumab followed by surgery, radiation and hormone therapy according to the indications. Before anticancer therapy the general clinical examination was conducted and lipid profle, plasma lipoprotein (a) [Lp(a)] level, titres of autoantibodies IgM and IgG to lipoproteins and their oxidized derivatives were estimated. Te vascular wall stiffness (pulse wave velocity on the carotid-femoral (PWVcf) and shoulder-ankle (PWVsa) segments, the central pressure, carotid intima-media thickness (CIMT) and the degree of stenosis of the brachiocephalic arteries) were determined at baseline and at each stage of anticancer therapy. Te atherosclerosis progression was determined if the new stenosis (≥15%) or increase of preexisting stenosis (≥5%) were revealed; CIMT increase ≥ 0.1 mm. Te parameters of cellular immunity (peripheral blood lymphocyte phenotyping via direct immunofluorescence and flow cytometry), lipid spectrum parameters, serum concentration of Lp (a), autoantibodies IgM and IgG against lipoproteins and their oxidized derivatives, as well as PWVсf and PWVsa were assessed in 17 BC patients before the onset of neoadjuvant therapy and in 20 healthy women.

RESULTS

BC patients and healthy women were comparable in traditional cardiovascular risk factors but differed in PWVsa and PWVcf levels (p&lt;0.05). In BC patients the activation of T-cell immunity with the stimulation of both subpopulations with pro-inflammatory and regulatory properties was observed (p&lt;0.05). Te direct correlations between the content of activated T-lymphocytes (T-act), T-helpers (T) 1 and PWVsa (p&lt;0.05), as well as T-act, T1 and T2 and PWVcf (p&lt;0.05) were revealed in the general group. Te decrease of systolic blood pressure (SBP), central SBP (SBPc), central diastolic blood pressure (DBPc), PWVcf and PWVsa levels accompanied with a temporary heart rate increase were observed during anticancer therapy; SBP, SBPc, PWVcf levels restored by the end of the follow-up period. Te CIMT increase was detected in 22 (51%), and the atherosclerosis progression in 26 (60%) BC patients during anticancer therapy. Lp (a) level above 12.8 mg/dl was associated with CIMT increase (p&lt;0.05). Age &gt; 48 years and radiation therapy were risk factors for CIMT increase and atherosclerosis progression (p&lt;0.05), respectively.

CONCLUSIONS

Te vascular stiffness is increased in BC patients, which is associated with the activation of effector subpopulations of T-lymphocytes and the elevation of circulating level of both pro-atherogenic and anti-atherogenic T-cells. Te level of Lp (a) above 12.8 mg/dl is associated with atherosclerosis progression, which requires further research. Age and radiation therapy are the risk factors for atherosclerosis progression during anticancer therapy.

Association of Resting Heart Rate With Arterial Stiffness and Low-Grade Inflammation in Women With Systemic Lupus Erythematosus

Resting heart rate (RHR) is associated with arterial stiffness, inflammation, and cardiovascular (CV) and all-cause mortality in the general population and in patients at high CV risk. We assessed the association of RHR with arterial stiffness and low-grade inflammation (LGI) in a cross-sectional study that included 101 women with systemic lupus erythematosus (SLE) without a history of CV disease or arrhythmia or who were under treatment that may cause bradycardia. Pulse wave velocity (PWV; a measure of arterial stiffness), RHR, and markers of LGI (ie, C-reactive protein, fibrinogen, erythrocyte sedimentation rate, insulin, and homeostatic model assessment index) were measured. The patients with the highest RHR (quartile 4; mean RHR = 87.2 bpm) had a PWV 0.61 m/s (95% confidence interval [CI]: 0.08-1.14; P = .024) greater than patients with the lowest RHR (quartile 1; RHR = 63.0 bpm), independent of age, systolic blood pressure, disease activity, smoking, and being physically inactive. Similarly, patients with the highest RHR (quartile 4) showed a significantly less favorable clustered LGI index than patients in quartile 1 ( b = .58; 95% CI: 0.212-0.948; P = .002). Higher RHR is associated with greater arterial stiffness and LGI in women with SLE. Further research to determine the prognostic value of RHR in this population is warranted.

Low-density lipoprotein cholesterol and survival in pulmonary arterial hypertension

Low-density lipoprotein cholesterol(LDL-C) is a well established metabolic marker of cardiovascular risk, however, its role in pulmonary arterial hypertension (PAH) has not been determined. Therefore we assessed whether LDL-C levels are altered in PAH patients, if they are associated with survival in this group and whether pulmonary hypertension (PH) reversal can influence LDL-C levels. Consecutive 46 PAH males and 94 females were age matched with a representative sample of 1168 males and 1245 females, respectively. Cox regression models were used to assess the association between LDL-C and mortality. The effect of PH reversal on LDL-C levels was assessed in 34 patients with chronic thromboembolic pulmonary hypertension (CTEPH) undergoing invasive treatment. LDL-C was lower in both PAH (2.6 ± 0.8 mmol/l) and CTEPH (2.7 ± 0.7 mmol/l) patients when compared to controls (3.2 ± 1.1 mmol/l, p < 0.001). In PAH patients lower LDL-C significantly predicted death (HR:0.44/1 mmol/l, 95%CI:0.26-0.74, p = 0.002) after a median follow-up time of 33(21-36) months. In the CTEPH group, LDL-C increased (from 2.6[2.1-3.2] to 4.0[2.8-4.9]mmol/l, p = 0.01) in patients with PH reversal but remained unchanged in other patients (2.4[2.2-2.7] vs 2.3[2.1-2.5]mmol/l, p = 0.51). We concluded that LDL-C level is low in patients with PAH and is associated with an increased risk of death. Reversal of PH increases LDL-C levels.

Arterial stiffness in adult patients after Fontan procedure

Objectives

Increased arterial stiffness is a risk factor of atherosclerosis and cardio-vascular complications. The aim of the study was to determine whether peripheral vascular function might be an early marker of impaired health status in patients with a single ventricle after Fontan procedure.

Methods and results

Twenty five consecutive adults (11 women and 14 men) aged 24.7 ± 6.2 years after the Fontan procedure and 25 sex, age and BMI match healthy volunteers underwent physical examination, blood analysis, transthoracic echocardiography and noninvasive assessment of aortic stiffness. Augmented pressure and Augmentation Index (AIx) were both significantly elevated in Fontan when compared to the controls (6,08 ± 0,7 vs. 2,0 ± 3,7; p = 0.002 and 17,01 ± 3,3 vs. 6,05 ± 11; p < 0.001, respectively). There were no differences in pulse wave velocity (PWV), mean blood pressure (BP), brachial pulse pressure (PP), central: systolic BP, diastolic BP and PP. In Fontan group we find negative correlation between PWV and SatO2 (r = −0.68; p = 0.04) and positive correlation with WBC (0.72; p = 0.72; p = 0.013), INR (0.81; p = 0.008), TNFα (r = 0.45; p = 0.04), and postoperative time (r = 0.77; p = 0.02). AIx correlates positively only with age at surgery (r = 0.45; p = 0.04). Bilirubin level correlates positively with brachial PP (r = 0.71; p = 0.02) and central PP (r = 0.68; p = 0.03).

The multivariate model showed that SatO2 (β = −0.44, p = 0.04) was the only independent predictor of PWV (R² = 0.32, p = 0.03).

Conclusion

Adult Fontan patients have an increased arterial stiffness assessed by a noninvasive technique. Low arterial oxygen saturation postoperative time, age at surgery, white blood cells, TNFα and bilirubin level are associated with arterial stiffening in these patients. The combination of blood parameters of the hepatic function and noninvasive measurements of arterial stiffness could be helpful in comprehensive care of patients with Fontan circulation.

Impaired endothelial function is not associated with arterial stiffness in adults with type 1 diabetes

AIM

This study investigated the relationship between endothelial dysfunction (ED) and arterial stiffness (AS) in adults with type 1 diabetes and no clinical cardiovascular (CV) disease.

METHODS

A total of 68 patients with type 1 diabetes and 68 age- and gender-matched healthy (non-diabetic) subjects were evaluated. ED was assessed by reactive hyperaemia peripheral arterial tonometry (RH-PAT) and by serum concentrations of soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1) and E-selectin. AS was assessed by aortic pulse wave velocity (aPWV). All statistical analyses were stratified by gender.

RESULTS

Adults with type 1 diabetes had RH-PAT index scores similar to those of their matching controls [men: 1.55 (1.38-1.98)% versus 1.61 (1.40-2.17)%, P=0.556; women: 2.07 (1.55-2.31)% versus 2.08 (1.79-2.49)%; P=0.215]. However, after adjusting for potential confounders, type 1 diabetes emerged as the main determinant of the RH-PAT index in women. Also, differences between genders in both the controls and type 1 diabetes patients disappeared. Men with diabetes had higher serum concentrations of E-selectin, and women had higher serum concentrations of sICAM-1, sVCAM-1 and E-selectin than their respective controls. However, after adjusting for potential confounders, only the differences in sICAM-1 (women) and E-selectin (both genders) remained significant. No association was found between aPWV and the RH-PAT index and ED markers after adjusting for CV risk factors.

CONCLUSION

ED was increased in adults with type 1 diabetes compared with age-matched non-diabetic subjects. Also, gender differences in ED were lost in type 1 diabetes. However, ED was not associated with AS after adjusting for potential confounders. These findings suggest that ED occurs earlier than AS in type 1 diabetes.

Pulmonary artery pulse wave velocity in idiopathic pulmonary arterial hypertension

BACKGROUND

Idiopathic pulmonary artery (PA) hypertension (IPAH) is associated with severe PA remodelling. Although the resulting increase in pulse wave velocity (PWV) might be of major pathophysiological relevance, little is known about PA-PWV in IPAH. The aim of this study was to characterize PA-PWV and its predictors in patients with IPAH.

METHODS

We studied 26 consecutive patients with incident IPAH aged 55.0 (45.0-66.0) years (62% female) and 10 control subjects without pulmonary hypertension. PA-PWV was measured invasively; PA wall thickness and diameter were assessed using intravascular and transthoracic ultrasonography.

RESULTS

PA-PWV was higher in IPAH than in control subjects (10.0 [7.5-14.0] m/s vs 3.5 [1.9-4.0] m/s; P < 0.001) as was also PA diameter and PA wall thickness. In IPAH patients, in univariate analysis PA-PWV was greater in men than in women and in patients with body mass index (BMI) < 25 kg/m(2) than with BMI ≥ 25 kg/m(2) and correlated positively with symptomatic disease duration, mean PA pressure, pulmonary vascular resistance, creatinine level, and negatively with low-density lipoprotein (LDL) cholesterol and triglyceride level but not with PA diameter or PA wall thickness. In multiple regression analysis mean PA pressure, LDL cholesterol level and BMI < 25 kg/m(2) were the main predictors of PA-PWV in IPAH patients (R(2) = 77%; P < 0.001).

CONCLUSIONS

PA-PWV is increased in IPAH patients. High PA pressure, low LDL cholesterol level, and BMI < 25 kg/m(2) explain most of its variability in this group.

Arterial micro-calcification of vascular access is associated with aortic arch calcification and arterial stiffness in hemodialysis patients

Vascular calcification of the coronary arteries or aorta is an independent risk factor for cardiovascular outcome, but clinical significance of arterial micro-calcification (AMC) of vascular access is unclear in hemodialysis (HD) patients. Sixty-five patients awaiting vascular access operation were enrolled. We compared surrogate markers of cardiovascular morbidity such as aortic arch calcification (AoAC) by chest radiography, arterial stiffness by brachial-ankle pulse wave velocity (baPWV) and endothelial dysfunction by flow-mediated dilatation (FMD) between patients with and without AMC of vascular access on von Kossa staining. AMC of vascular access was detected in 36 (55.4%). The AMC-positive group had significantly higher incidence of AoAC (63.9% vs. 20.7%, p < 0.001) and higher baPWV (26.5 ± 9.4 m/s vs. 19.8 ± 6.6 m/s, p = 0.006) than the AMC-negative group. There was no significant difference in FMD between the two groups (5.4 ± 2.6% vs. 5.7 ± 3.5%, p = 0.764). The AMC-positive group had higher incidence of diabetes mellitus, higher systolic blood pressure and wider pulse pressure than the AMC-negative group. This study suggests that AMC of vascular access may be associated with cardiovascular morbidity via AoAC and arterial stiffness in HD patients.

Type 2 diabetes mellitus worsens arterial stiffness in hypertensive patients through endothelial dysfunction

AIMS/HYPOTHESIS

Endothelium-derived factors are thought to be physiological modulators of large artery stiffness. The aim of the study was to investigate whether endothelial function could be a determinant of arterial stiffness in essential hypertensive patients, in relation with the concomitant presence of type 2 diabetes mellitus.

METHODS

The study included 341 participants (84 hypertensive patients with and 175 without type 2 diabetes mellitus, 82 matched controls). Brachial artery endothelium-dependent flow-mediated dilation (FMD) was determined by high-resolution ultrasound and computerised edge detection system. Applanation tonometry was used to measure carotid-femoral pulse wave velocity (PWV).

RESULTS

Hypertensive patients with diabetes had higher PWV (10.1 ± 2.3 m/s vs 8.6 ± 1.4 m/s, p < 0.001) and lower FMD (3.51 ± 2.07 vs 5.16 ± 2.96%, p < 0.001) than non-diabetic hypertensive patients, who showed impaired vascular function when compared with healthy participants (7.9 ± 1.6 m/s and 6.68 ± 3.67%). FMD was significantly and negatively correlated to PWV only in hypertensive diabetic patients (r = -0.456, p < 0.001), but not in hypertensive normoglycaemic patients (r = -0.088, p = 0.248) or in healthy participants (r = 0.008, p = 0.946). Multivariate analysis demonstrated that, in the diabetic group, FMD remained an independent predictor of PWV after adjustment for confounders (r(2) = 0.083, p = 0.003). Subgroup analysis performed in non-diabetic hypertensive patients revealed that neither obesity nor the metabolic syndrome affected the relationship between FMD and PWV.

CONCLUSIONS/INTERPRETATION

Endothelial dysfunction is a determinant of aortic stiffness in hypertensive diabetic patients but not in hypertensive patients without diabetes. These results suggest that type 2 diabetes mellitus on top of hypertension might worsen arterial compliance by endothelium-related mechanisms.

Does uremia cause vascular dysfunction?

Vascular dysfunction induced by uremia has 4 main aspects. (1) Atherosclerosis is increased. Intima-media thickness is increased, and animal studies have established that uremia accelerates atherosclerosis. Uremic toxins are involved in several steps of atherosclerosis. Leukocyte activation is stimulated by guanidines, advanced glycation end products (AGE), p-cresyl sulfate, platelet diadenosine polyphosphates, and indoxyl sulfate. Endothelial adhesion molecules are stimulated by indoxyl sulfate. Migration and proliferation of vascular smooth muscle cells (VSMC) are stimulated by local inflammation which could be triggered by indoxyl sulfate and AGE. Uremia is associated with an increase in von Willebrand factor, thrombomodulin, plasminogen activator inhibitor 1, and matrix metalloproteinases. These factors contribute to thrombosis and plaque destabilization. There is also a decrease in nitric oxide (NO) availability, due to asymmetric dimethylarginine (ADMA), AGE, and oxidative stress. Moreover, circulating endothelial microparticles (EMP) are increased in uremia, and inhibit the NO pathway. EMP are induced in vitro by indoxyl sulfate and p-cresyl sulfate. (2) Arterial stiffness occurs due to the loss of compliance of the vascular wall which induces an increase in pulse pressure leading to left ventricular hypertrophy and a decrease in coronary perfusion. Implicated uremic toxins are ADMA, AGE, and oxidative stress. (3) Vascular calcifications are increased in uremia. Their formation involves a transdifferentiation process of VSMC into osteoblast-like cells. Implicated uremic toxins are mainly inorganic phosphate, as well as reactive oxygen species, tumor necrosis factor and leptin. (4) Abnormalities of vascular repair and neointimal hyperplasia are due to VSMC proliferation and lead to severe reduction of vascular lumen. Restenosis after coronary angioplasty is higher in dialysis than in nondialysis patients. Arteriovenous fistula stenosis is the most common cause of thrombosis. Uremic toxins such as indoxyl sulfate and some guanidine compounds inhibit endothelial proliferation and wound repair. Endothelial progenitor cells which contribute to vessel repair are decreased and impaired in uremia, related to high serum levels of β(2)-microglobulin and indole-3 acetic acid. Overall, there is a link between kidney function and cardiovascular risk, as emphasized by recent meta-analyses. Moreover, an association has been reported between cardiovascular mortality and uremic toxins such as indoxyl sulfate, p-cresol and p-cresyl sulfate.

The effect of smoking on arterial stiffness

A systematic literature review was conducted using PubMed, Embase and the Cochrane Library to determine the effect of acute, chronic and passive smoking on arterial stiffness and to determine whether these effects are reversible after smoking cessation. A total of 39 relevant studies were identified and included. Acute smoking was found to cause an acute increase in arterial stiffness. Similarly, passive smoking increased arterial stiffness acutely and chronically. The majority of studies identified chronic smoking as a risk factor for increasing arterial stiffness. However, some studies found no statistical difference in arterial stiffness between nonsmokers and long-term smokers, although chronic smoking seems to sensitize the arterial response to acute smoking. In addition, whether arterial stiffness is reversed after smoking cessation and the timeline in which this may occur could not be determined from the identified literature. The effect of smoking discontinuation on arterial stiffness remains to be established by prospective smoking cessation trials.