Biomedical subjects

Nikolaos Alexopoulos

Publications and source records attributed to Nikolaos Alexopoulos.

13 recordsLinked to original sources

PubMed2006

Unfavourable endothelial and inflammatory state in erectile dysfunction patients with or without coronary artery disease.

AIMS: Erectile dysfunction (ED) confers an independent cardiovascular risk. We investigated the role of low-grade inflammation and endothelial dysfunction in ED patients with or without coronary artery disease (CAD). METHODS AND RESULTS: We evaluated 141 men (age 58.8 years) for ED and CAD through a rigourous investigation (including coronary angiography to reveal occult CAD). Blood levels of inflammatory (hsCRP, IL-6, IL-1beta, and TNF-alpha) and endothelial-prothrombotic markers/mediators (vWF, tPA, PAI-1, and fibrinogen) were significantly increased in ED patients and correlated negatively with sexual performance. ED was associated with higher levels of these substances (except for IL-6) on top of CAD alone. For most substances, the unfavourable impact of ED alone was not significantly different than the impact of CAD alone. In multivariable models, these markers/mediators predicted independently ED presence. In our population, the negative predictive value of the combination of fibrinogen <225 mg/dL with IL-6 <1.24 pg/mL for excluding ED was 91.7% (95% CI: 61.5-99.8). CONCLUSION: ED is associated with increased inflammatory and endothelial-prothrombotic activation in men with or without CAD. ED confers an incremental unfavourable impact on the circulating levels of these markers/mediators when combined with CAD. These findings have implications for increased cardiovascular risk in ED patients.

Biomarkers↗

PubMed2006

Effect of dark chocolate on arterial function in healthy individuals: cocoa instead of ambrosia?

Cocoa has been consumed for at least 2500 years, and for long time it has been regarded as a medicine. Arterial function is of paramount importance for the proper function and integrity of the cardiovascular system. Dark chocolate and flavonoid-rich cocoa have beneficial acute and short-term effects on endothelial function and wave reflections in normal individuals, in adults with cardiovascular risk factors, and in patients with coronary artery disease. Furthermore, dark chocolate and flavonoid-rich cocoa may have a blood pressure-lowering effect. These effects can be attributed to flavonoids and are mainly mediated through increased nitric oxide bioavailability. Further research is needed to demonstrate whether these effects of chocolate on arterial function are translated into clinical benefit.

Ambrosia↗

PubMed2006

Acute effect of black and green tea on aortic stiffness and wave reflections.

OBJECTIVE: While most studies have shown an inverse relation between tea consumption and cardiovascular risk, other studies have shown opposite results. Aortic stiffness and wave reflections are markers of cardiovascular disease and prognosticators of cardiovascular risk. METHODS: The acute effect of black and green tea on aortic stiffness and wave reflections was assessed in 29 healthy volunteers in a randomized, single-blind, sham-procedure controlled, cross-over design. In the black tea sub-study, 16 subjects received 6 gm of tea, caffeine (175 mg), or hot water in 3 different sessions. In the green tea sub-study, 13 subjects received 6 gm of tea, caffeine (125 mg), or hot water. Carotid-femoral pulse wave velocity and wave reflection indices were measured at baseline and for 3 hours after consumption. RESULTS: Black tea increased pulse wave velocity during the first 90 min (increase by 0.49 m/sec, P < 0.05), showing a rapid return towards baseline values thereafter (P = 0.07 for the whole study period); in contrast, green tea had no effect. Both black and green tea increased augmentation index (by 5.0% and by 6.6%, P < 0.01 and P < 0.001, respectively) throughout the study. These changes were less than the respective changes produced by caffeine. Both black and green tea had a significant pressor effect. No change in oxidant status was found with both types of tea. CONCLUSIONS: Both black and green tea increases acutely wave reflections and only black tea increases aortic stiffness. Tea flavonoids may play a role in the attenuation of the effects of caffeine contained in tea.

Adult↗

PubMed2006

Nonlinear dynamics of blood pressure variability after caffeine consumption.

OBJECTIVES: The occurrence of continuous blood pressure (BP) fluctuations is an intrinsic feature of the cardiovascular system and is related to complex cardiovascular mechanisms and environmental stimulations or daily habits such as coffee drinking. The aim of this study was to investigate the effect of caffeine on indices expressing the complex and "chaotic" nonlinear characteristics of BP variability. DESIGN: Fourteen healthy subjects consumed 240 mg of caffeine or placebo according to a randomized, double-blind, crossover design. Continuous radial pressure waveforms were recorded by applanation tonometry at baseline and at 30, 60, 90 and 120 minutes after ingestion of caffeine or placebo. METHODS: Approximate entropy (ApEn) was determined to assess BP irregularity. Detrended fluctuation analysis was also used to quantify the fractal correlation properties of the BP data by estimating the scaling (self-similarity) exponent alpha. Analysis of variance for repeated measurements was used to detect significant changes in the measured variables at 30, 60, 90 and 120 minutes after ingestion of caffeine or placebo. RESULTS: BP fluctuations demonstrated high regularity and predictability as indicated by the low values of ApEn (0.2 +/- 0.3), and they remained unchanged after caffeine ingestion. In contrast, the long-term scaling exponent alpha of the BP time series was significantly increased from 0.99 to 1.04 (p=0.01) after caffeine ingestion, while the placebo induced no significant change. CONCLUSIONS: Caffeine induced greater "randomness" in BP fluctuations, possibly by triggering cardiovascular mechanisms that could not be directly specified but should be investigated in future studies.

Adult↗

PubMed2005

Changes in aortic root function after valve replacement in patients with aortic stenosis.

BACKGROUND: Aortic elastic properties are compromised in various states that induce functional and histological changes in the aortic wall. Aortic stenosis is frequent and often requires replacement of the stenotic valve. The purpose of this study was to examine the effect of aortic valve replacement on the aortic root function. METHODS: 31 patients, mean+/-SD age 67.2+/-9.1 years with severe aortic stenosis, who underwent aortic valve replacement with a bileaflet mechanical prosthesis, were studied. Aortic root function indices such as aortic cross-sectional compliance (CSC), aortic root distensibility (ARD), and aortic stiffness index (ASI) were calculated with the use of M-mode echocardiography in three sessions: one preoperatively (pre-op), one on day 7 postoperatively (early post-op), and one 6 months postoperatively (late post-op). RESULTS: Aortic root function deteriorated early post-op (p<0.001 for all) and returned towards pre-op levels late post-op (p=NS for all). CSC changed from 2.84+/-1.98 to 1.37+/-0.92, and 2.30+/-1.11 cm2/mmHg, ARD from 2.21+/-5.60 to 1.01+/-0.67, and 1.79+/-0.96 cm2/dyne, and ASI from 9.72+/-5.60 to 24.65+/-19.10, and 11.51+/-7.85, respectively. Correlations were found between early changes in some aortic root indices and the degree of aortic stenosis, denoting that aortic function deteriorated less in more severe cases of aortic stenosis. None of the late changes were related to aortic valve or left ventricular indices. CONCLUSIONS: Aortic valve replacement with a mechanical valve results in a significant but transient impairment of aortic distensibility.

Aged↗

PubMed2005

Effect of dark chocolate on arterial function in healthy individuals.

BACKGROUND: Epidemiologic studies suggest that high flavonoid intake confers a benefit on cardiovascular outcome. Endothelial function, arterial stiffness, and wave reflections are important determinants of cardiovascular performance and are predictors of cardiovascular risk. METHODS: The effect of flavonoid-rich dark chocolate (100 g) on endothelial function, aortic stiffness, wave reflections, and oxidant status were studied for 3 h in 17 young healthy volunteers according to a randomized, single-blind, sham procedure-controlled, cross-over protocol. Flow-mediated dilation (FMD) of the brachial artery, aortic augmentation index (AIx), and carotid-femoral pulse wave velocity (PWV) were used as measures of endothelial function, wave reflections, and aortic stiffness, respectively. Plasma oxidant status was evaluated with measurement of plasma malondialdehyde (MDA) and total antioxidant capacity (TAC). RESULTS: Chocolate led to a significant increase in resting and hyperemic brachial artery diameter throughout the study (maximum increase by 0.15 mm and 0.18 mm, respectively, P < .001 for both). The FMD increased significantly at 60 min (absolute increase 1.43%, P < .05). The AIx was significantly decreased with chocolate throughout the study (maximum absolute decrease 7.8%, P < .001), indicating a decrease in wave reflections, whereas PWV did not change to a significant extent. Plasma MDA and TAC did not change after chocolate, indicating no alterations in plasma oxidant status. CONCLUSIONS: Our study shows for the first time that consumption of dark chocolate acutely decreases wave reflections, that it does not affect aortic stiffness, and that it may exert a beneficial effect on endothelial function in healthy adults. Chocolate consumption may exert a protective effect on the cardiovascular system; further studies are warranted to assess any long-term effects.

Adult↗

PubMed2005

Tissue Doppler imaging and brain natriuretic peptide levels in adults with repaired tetralogy of Fallot.

BACKGROUND: Accurate estimation of right ventricular (RV) function in patients with repaired tetralogy of Fallot (RTOF) is difficult, partly due to the presence of tricuspid regurgitation and pulmonary regurgitation and/or stenosis. The aim of the present study was to evaluate RV systolic and diastolic function of adult asymptomatic patients with RTOF by means of tissue Doppler imaging (TDI) and brain natriuretic peptide (BNP) values. METHODS: 25 adult patients with RTOF and 25 healthy controls were studied. The following echocardiographic measurements were obtained: RV diameter/left ventricular (LV) diameter (RVD/LVD) and systolic (Sa) and diastolic (Ea, Aa) velocities at the RV free wall tricuspid annulus site. Serum BNP levels were measured as well. RESULTS: Patients with RTOF demonstrated reduced TDI velocities: Sa, 8.16 +/- 1.15 versus 16.43 +/- 1.15 cm/sec (P < .001); Ea, 10.00 +/- 2.18 versus 18.99 +/- 1.00 cm/sec (P < .001); Aa, 5.64 +/- 1.77 vs. 13.69 +/- 0.86 cm/sec (P < .001). Patients with RTOF also had higher BNP levels than controls (85.0 +/- 87.0 vs 5.36 +/- 1.0 pg/mL; P < .001). The increased BNP levels in RTOF patients correlated with the RVD/LVD ratio (r = .521; P < .01). CONCLUSIONS: Our results indicate that although our cohort of patients was asymptomatic, using TDI and BNP allowed us to easily discriminate them from the healthy controls. The ability of TDI to assess ventricular function even in the presence of valvular lesions, as in RTOF patients, makes it a valuable tool in the investigation and follow-up of these patients.

Adolescent↗

PubMed2004

Smoking and caffeine have a synergistic detrimental effect on aortic stiffness and wave reflections.

OBJECTIVES: We investigated the acute and chronic combined effect of cigarette smoking and caffeine intake on aortic stiffness and wave reflections. BACKGROUND: We have shown that smoking and caffeine separately increase arterial stiffness. Aortic stiffness and wave reflections are important determinants of the efficient performance of the cardiovascular system and prognosticators of cardiovascular risk. METHODS: The acute effects of smoking (one cigarette), caffeine (200 mg, equivalent to 2 cups of coffee), and smoking plus caffeine were studied in 24 healthy subjects according to a randomized, placebo- and sham procedure-controlled crossover design. The chronic effect of smoking and caffeine was studied in a population study that enrolled 160 healthy subjects. RESULTS: Acute study: there was a significant interaction between caffeine and smoking with regard to pulse-wave velocity (p < 0.01) and augmentation index (p < 0.05). When smoking followed caffeine intake, pulse-wave velocity and augmentation index increased further by 0.52 m/s and 13.4%, respectively, reaching a total of 0.85 m/s and 17.4%, 0.17 m/s and 9.2% in excess of the mere sum of caffeine effect (0.33 m/s and 4%) alone and smoking effect alone (0.35 m/s and 4.2%). Population study: there was a significant interaction of chronic coffee consumption and smoking regarding pulse-wave velocity (p < 0.05) and augmentation index (p = 0.001). CONCLUSIONS: The present study shows, for the first time, that when smoking and caffeine intake are combined, they interact and exert a synergistic, unfavorable effect on aortic stiffness and wave reflections on both an acute and chronic basis.

Adult↗

PubMed2004

Cigar smoking has an acute detrimental effect on arterial stiffness.

BACKGROUND: Despite a decline in cigarette smoking, cigar smoking is increasing, partly due to the perception that it is a "safe" alternative to cigarettes. However, cigar smoking increases cardiovascular risk, but the mechanisms involved are not fully explored. Aortic stiffness and arterial wave reflection are important factors for the efficient performance of the cardiovascular system and have been identified as prognosticators of cardiovascular risk. We investigated the acute effect of cigar smoking on aortic elastic properties and wave reflection. METHODS: We studied the effect of smoking one cigar in 12 healthy subjects according to a randomized, sham procedure-controlled, cross-over design. Aortic stiffness was evaluated with carotid-femoral pulse wave velocity and wave reflection with augmentation index of the aortic pressure waveform. RESULTS: Cigar smoking produced a significant increase in pulse wave velocity (by 0.80 m/sec, P = .001) denoting an increase in aortic stiffness. Augmentation index increased significantly (by 6.1%, P < .05) denoting an increase of wave reflections. These increases in arterial stiffness indices were evident promptly after the initiation of cigar smoking and lasted throughout the duration of the study (2 h). Concurrently, both radial and aortic systolic, and pulse pressure increased significantly throughout the study. CONCLUSIONS: The present study shows for the first time that cigar smoking increases acutely stiffness of large arteries and wave reflection, thus providing further evidence that it is not a safe alternative to cigarettes.

Adult↗

PubMed2004

Type 5 phosphodiesterase inhibition by sildenafil abrogates acute smoking-induced endothelial dysfunction.

BACKGROUND: Endothelial dysfunction is a key early event in the process of atherosclerosis and a risk factor for cardiovascular events. Sildenafil, an effective oral treatment for patients with erectile dysfunction, inhibits cGMP degradation by specific type 5 phosphodiesterase (PDE) inhibition. Sildenafil has been shown to improve vascular function, however, the effect of type 5 PDE inhibition on acute smoking-induced endothelial dysfunction is unknown. METHODS: We studied the effect of 50 mg of sildenafil on acute smoking-induced endothelial dysfunction in 14 male smokers according to a randomized, placebo-controlled, cross-over design. Endothelial function was evaluated with flow-mediated dilatation (FMD) of the brachial artery using high-resolution ultrasonography. RESULTS: Sildenafil abolishes the decrease in FMD of the brachial artery that is induced acutely by smoking (placebo/smoking session: from 4.56% +/- 0.60% to 2.80% +/- 0.43%, sildenafil/smoking session: from 3.83% +/- 0.64% to 4.33% +/- 0.47%, ie, improvement of 51%, P < .05). This was associated with no reversal effect of sildenafil on smoking-induced decrease in resting brachial artery diameter and with a partial reversal of the smoking-induced decrease in hyperemic brachial artery diameter (placebo/smoking session: from 4.68 +/- 0.13 mm to 4.53 +/- 0.15 mm, sildenafil/smoking session: from 4.72 +/- 0.12 mm to 4.64 +/- 0.13 mm, ie, improvement of 1.5%, P < .005). CONCLUSIONS: The present study shows, for the first time, that type 5 PDE inhibition with sildenafil abrogates the smoking-induced acute decrease in FMD of the brachial artery. These findings may have clinical implications given the detrimental consequences of smoking and the strategic role of normal endothelial function.

Acute Disease↗

PubMedDate not supplied

Acute mental stress has a prolonged unfavorable effect on arterial stiffness and wave reflections.

OBJECTIVE: Large-artery stiffness and arterial wave reflections have been identified as independent markers and prognosticators of cardiovascular risk. Mental stress is a novel risk factor for coronary artery disease and has been associated with left ventricular dysfunction, myocardial ischemia and infarction, and sudden cardiac death. The purpose of this study was to assess the effect of acute mental stress on aortic stiffness and wave reflections. METHODS: The effect of a mental arithmetic test was assessed in 19 healthy individuals using a randomized, sham-procedure-controlled, crossover design. Carotid-femoral pulse wave velocity and augmentation index were measured as indices of aortic stiffness and wave reflections, respectively. RESULTS: Mental stress induced a sustained increase in central systolic and pulse pressure throughout the whole study (systolic: by 7.5 mm Hg, p < .05; pulse: by 5.7 mm Hg, p < .01). The increase in peripheral systolic and pulse pressure was not significant throughout the study, but only when their peak values were compared with baseline (systolic: by 6.2 mm Hg, peak at 0 minutes; pulse: by 6.6 mm Hg, peak at 5 minutes, p < .05 for both). There was a sustained increase in pulse wave velocity (by 0.57 m/s, p < .005) throughout the study denoting a sustained increase in aortic stiffness. Similarly, augmentation index showed a sustained increase with mental stress (by 6.16%, p < .05) denoting increased wave reflections from the periphery. CONCLUSION: Acute mental stress results in a prolonged increase in aortic stiffness and wave reflections. Given the important pathophysiologic and prognostic role of these parameters, our results provide important mechanistic links between acute mental stress and increased cardiovascular risk.

Adult↗

PubMedDate not supplied

Aortic pain associated with deteriorated aortic elastic properties: an early manifestation of aortopathy.

With the exception of acute aortic dissection, the aorta is not widely considered as a symptom-producing organ. However, chest pain may be of aortic origin in the absence of dissection; deteriorated aortic elastic properties may facilitate the occurrence of symptoms. We describe chest pain of aortic origin in a 60-year-old patient with a stiff, dilated but non-dissected aorta. Attention to aortic elastic properties may help exploration of the etiologic and mechanistic environment in which aortic pain occurs, thus identifying a special subgroup of patients who require special monitoring and therapeutic approaches.

Aorta, Thoracic↗

PubMedDate not supplied

The acute and chronic effect of cigarette smoking on the elastic properties of the ascending aorta in healthy male subjects.

INTRODUCTION: Aortic elastic properties are markers and prognosticators of cardiovascular risk. Smoking adversely affects arterial elastic properties. The acute and chronic effect of cigarette smoking on the elastic properties of the ascending aorta has not been determined. METHODS: The chronic part of the study included 130 healthy male subjects (age 38.1+/-8.9 years, 85 smokers and 45 non-smokers) with no other risk factors for cardiovascular disease. Twenty of the smokers (age 40.0+/-4.2 years) were also included in the acute study. In the acute study each subject was studied on two occasions: one while smoking one cigarette and the other during sham smoking. Ascending aortic distensibility was assessed by two-dimensional, guided, M-mode transthoracic echocardiography of the aortic root at baseline and at the end of smoking. In the chronic study the association was assessed between smoking status and ascending aortic distensibility. RESULTS: Smoking acutely increased systolic, diastolic, and pulse pressure. Furthermore, smoking decreased ascending aortic distensibility (by 0.53+/-0.86 cm(2) x dyne(-1) x 10(-6), p<0.05). The chronic study showed that smokers had greater ascending aortic distensibility than non-smokers (2.22+/-0.93 vs. 2.75+/-1.07 cm(2) x dyne(-1) x 10(-6), respectively, p<0.05). Aortic distensibility was independently associated with smoking (beta=-0.293, p<0.001) after controlling for possible confounders. No association of aortic distensibility with the intensity or duration of smoking was observed within the group of smokers. CONCLUSIONS: Cigarette smoking results acutely in a deterioration of ascending aortic elastic properties in healthy male subjects. On a chronic basis, smokers have decreased ascending aortic distensibility compared to non-smokers. This effect of smoking on aortic distensibility is not related to dose or duration.

Adult↗