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Biomedical subjects

Panos E Vardas

Publications and source records attributed to Panos E Vardas.

At least 19 recordsLinked to original sources
PubMed2006

Androgen deficiency and endothelial dysfunction in men with end-stage kidney disease receiving maintenance hemodialysis.

OBJECTIVES AND METHODS: Two thirds of men with end-stage kidney disease (ESKD) have serum testosterone levels in the hypogonadal range. We examined if low serum testosterone levels were correlated with measures of endothelial dysfunction in ESKD. Bilateral common carotid artery (CCA) intima-media thickness (IMT) and atherosclerotic plaque occurrence, left ventricular mass index, flow- (FMD) and nitrate-mediated vasodilatation (NMD) of the brachial artery were determined by ultrasound imaging in 100 nondiabetic men with ESKD (50 men exhibited androgen deficiency; serum testosterone concentrations <300 ng/dl). RESULTS: Left-ventricular mass index, CCA diameter, CCA-IMT and atherosclerotic plaque occurrence were all significantly increased in ESKD patients with androgen deficiency compared with patients without androgen deficiency (p < 0.05). Also, FMD and NMD measurements were significantly reduced in the former compared with the latter (p < 0.05). Testosterone levels were inversely correlated with age and duration of hemodialysis therapy (r = -0.44 and r = -0.55; p < 0.001). Testosterone levels were negatively correlated to CCA-IMT and atherosclerotic plaque occurrence in patients with androgen deficiency (r = -0.32, p < 0.003, and r = -0.23, p < 0.04, respectively). FMD and NMD measurements were positively correlated to total (r = 0.65 and r = 0.61; both p < 0.0001) and free (r = 0.52 and r = 0.48; both p < 0.001) testosterone levels in patients with low androgenicity. CONCLUSION: The present results indicated that ESKD patients with androgen deficiency had increased CCA-IMT, atherosclerotic plaque occurrence and reduced FMD and NMD compared with patients without androgen deficiency. Testosterone serum levels were negatively correlated to CCA-IMT and positively correlated to endothelium-dependent vasodilatation in ESKD patients with androgen deficiency.

Adult↗
PubMed2006

Atrial fibrillation is associated with increased neurohumoral activation and reduced exercise tolerance in patients with non-ischemic dilated cardiomyopathy.

OBJECTIVES: To assess atrial fibrillation (AF) associated differences in proinflammatory cytokines, natriuretic peptide levels and exercise capacity in patients with heart failure (HF) secondary to non-ischemic dilated cardiomyopathy (NIDC). METHODS: We studied 147 NIDC patients, mean age 58.3+/-12.5 years, left ventricular (LV) ejection fraction 27.8+/-10.9% and NYHA class II-III. Neurohumoral activation was assessed by measurement of interleukin IL-1, IL-6, tumor necrosis factor-a (TNF-a), its soluble receptors sTNFR I and II, N-terminal atrial (NT-ANP) and -brain (NT-BNP) natriuretic peptide levels, and functional class was assessed by cardiopulmonary exercise test. RESULTS: Forty patients (27.5%) had chronic AF and they did not differ in age, LV ejection fraction or HF duration compared to patients in sinus rhythm (SR). AF was associated with increased levels of IL-6 (p=0.001), TNF-a (p=0.002), sTNFRI (p=0.023), NT-ANP (p<0.001) and NT-BNP (p=0.003), decreased exercise duration (p<0.001) and slightly reduced maximal oxygen consumption at peak exercise (p=0.07) compared to SR patients. No significant differences in cytokine and natriuretic peptide levels or exercise tolerance were noted when patients in AF were compared to the subgroup of SR with restrictive LV filling pattern. Multivariate analysis showed that NT-ANP (p=0.003) and IL-6 (p=0.006) plasma levels were independently associated with the presence of AF in our patient population. CONCLUSION: AF is associated with increased inflammatory state, natriuretic peptide levels and reduced exercise capacity in patients with HF secondary to NIDC. These findings suggest that the presence of AF in HF represents a more advanced stage of the syndrome.

Atrial Fibrillation↗
PubMed2006

Evidence of mechanoelectric feedback in the atria of patients with atrioventricular nodal reentrant tachycardia.

OBJECTIVE: Patients with atrioventricular nodal reentrant tachycardia (AVNRT) could serve as a clinical model to study the effects of mechanical stretch in the electrical properties of atrial myocardium. MATERIALS AND METHODS: We studied 14 patients with AVNRT. Peak, mean and minimal atrial pressures, atrial refractoriness (ERP) in the right atrial appendage and high right atrial lateral wall and monophasic action potential duration at 90% of repolarisation (MAPd90) in the right atrial appendage were assessed during atrial pacing at 500 and 400 ms and after 2 min of pacing at the tachycardia cycle length. Measurements were repeated from the same positions after ventricular pacing at the same cycle lengths and after 2 min of tachycardia. Susceptibility to atrial fibrillation (AF) was assessed by noting whether AF was induced during ERP evaluation. RESULTS: Atrial pressure showed a statistically significant increase during ventricular pacing compared to baseline. This increase remained substantially unchanged when the tachycardia was induced. A significant reduction in atrial ERP and MAPd90 was also observed during ventricular pacing at all cycle lengths compared to atrial pacing. Two minutes of spontaneous tachycardia were enough to change the atrial ERP and MAPd90 to values significantly lower than those during atrial pacing at the cycle length of tachycardia. During the ERP evaluation AF was induced more often during the tachycardia (28%) than during ventricular (14%) and atrial pacing (0%). CONCLUSION: In AVNRT patients, ventricular pacing and reentrant tachycardia significantly increase right atrial pressures and subsequently shorten ERP and MAPd90, leading to an enhanced propensity for AF.

Adolescent↗
PubMed2006

Reduced systemic inflammatory response to implantation of sirolimus-eluting stents in patients with stable coronary artery disease.

Stent implantation causes significant injury to the vascular wall, resulting in inflammatory activation. Although sirolimus-eluting stents (SES) have anti-inflammatory properties, their effect on periprocedural systemic inflammatory response has not been sufficiently investigated. Eighty-one patients with stable coronary artery disease involving severe stenosis of one major epicardial coronary artery underwent coronary angioplasty with stent implantation and randomly received either SES or bare metal stents (BMS). Blood samples were taken 24h before, at 24h, 48 h and 1 month after the angioplasty and levels of high sensitive C-reactive protein (hsCRP), interleukin-6 (IL-6), interleukin-1 beta (IL-1 beta), and monocyte chemoattractant protein-1 (MCP-1) were determined. HsCRP after BMS implantation increased over 24h (p<0.001) and then remained steady, as did IL-6 and IL-1 beta similarly. In contrast, their levels in SES patients decreased to below baseline by the end of the month. MCP-1 levels increased by the end of 1 month (p<0.001) in the BMS group, whereas in SES they steadily decreased, becoming significantly lower than baseline from 48 h (p=0.015). In conclusion, patients with SES exhibit an attenuation of the postprocedural systemic inflammatory activation during a 1-month follow-up after stent implantation. This might partially explain the reduced restenosis rate associated with SES.

Aged↗
PubMed2006

Effect of inhaled salbutamol on coronary circulation in humans.

In 12 patients we assessed the effect of inhaled salbutamol on the coronary circulation. According to our results, large doses of salbutamol increase coronary flow, but not in proportion to the needs of the myocardium (as documented by the increase in coronary oxygen extraction), and decrease coronary flow reserve. These effects may have deleterious consequences in patients with coronary artery disease, causing or worsening myocardial ischemia.

Administration, Inhalation↗
PubMed2006

Antithrombotic treatment in real-life atrial fibrillation patients: a report from the Euro Heart Survey on Atrial Fibrillation.

AIMS: To describe guideline adherence and application of different stroke risk stratification schemes regarding antithrombotic therapy in real-life atrial fibrillation (AF) patients and to assess which factors influence antithrombotic management decisions. METHODS AND RESULTS: The Euro Heart Survey enrolled 5333 AF patients in 35 countries, in 2003 and 2004. Prescription of antithrombotic drugs, especially oral anticoagulation (OAC), was hardly tailored to the patient's stroke risk profile as indicated by the joint guidelines of the American College of Cardiology, American Heart Association, and the European Society of Cardiology, ACCP guidelines, or CHADS(2) and Framingham risk scores. In multivariable analysis, only a limited number of the well-known stroke risk factors triggered OAC prescription. In contrast, less relevant factors, of which clinical type of AF and availability of an OAC monitoring outpatient clinic were the most marked, played a significant role in OAC prescription. Electrical cardioversions and catheter ablations clearly triggered OAC prescription, whereas pharmacological cardioversions even in the presence of stroke risk factors did not. CONCLUSION: Antithrombotic therapy in AF is hardly tailored to the patient's stroke risk profile. Factors other than well-known stroke risk factors were significantly involved in antithrombotic management decisions. To facilitate this tailored treatment, guideline writers and physician educators should focus on providing one uniform and easy to use stroke risk stratification scheme.

Adult↗
PubMed2006

Clarithromycin treatment and QT prolongation in childhood.

UNLABELLED: The effect of clarithromycin on the QT interval was studied in a group of 28 children treated for respiratory tract infections. QTc was measured before and following 24 h of treatment. A modest (average 22 ms, 95% CI 14-30 ms) but significant QTc prolongation (p<0.001) was observed, with seven cases having a QTc >440 ms during treatment (including a single case with QTc >460 ms). CONCLUSION: Serial QTc measurements are necessary for early detection of children at risk for drug-induced arrhythmias.

Adolescent↗
PubMed2006

Cardiac pacing in sleep apnoea: diagnostic and therapeutic implications.

The sleep apnoea syndrome is a particularly common health problem associated with increased cardiovascular morbidity and mortality, as well as harmful socioeconomical and familial complications. In this article, the diagnostic and therapeutic role of cardiac pacing in this syndrome is discussed.

Cardiac Pacing, Artificial↗
PubMed2006

Drug therapy for atrial fibrillation.

Although the maintenance of sinus rhythm would be the ideal scenario for patients with atrial fibrillation (AF), recent randomised trials have questioned the value of this approach. A careful interpretation of their results showed the limited efficacy of currently available antiarrhythmic drugs in maintaining sinus rhythm, as well as their potentially serious side effects. Therefore, it is imperative to develop safer and more effective drugs for AF. Based on our improved understanding of the pathophysiology of AF and the mechanism of action of antiarrhythmic drugs, significant efforts are being made to develop new antiarrhythmic agents that would prevent electrophysiological remodelling, would be selective for the atria and, therefore, would not prolong ventricular repolarisation, thus lacking any proarrhythmic effect.

Adrenergic beta-Antagonists↗
PubMed2005

Atrial overdrive pacing for the obstructive sleep apnea-hypopnea syndrome.

BACKGROUND: The role of atrial overdrive pacing (AOP) in sleep apnea remains uncertain. We prospectively evaluated the effect of AOP after 24 hours and after one month in patients with the obstructive sleep apnea-hypopnea syndrome and compared it with the use of nasal continuous positive airway pressure (n-CPAP). METHODS: We studied 16 patients with a moderate or severe case of the obstructive sleep apnea-hypopnea syndrome (baseline mean apnea-hypopnea index, 49) and normal left ventricular systolic function in whom a dual-chamber pacemaker had been implanted. After 48 hours, the patients were randomly assigned to AOP (pacing at 15 bpm above the spontaneous mean nocturnal heart rate) or backup atrial pacing (pacing at a heart rate below 40 bpm); the latter group began n-CPAP therapy one day later. After one month, the two groups switched therapies and were followed for an additional month. Polysomnographic studies were performed at baseline, on the first night after randomization, at crossover, and at the end of the study. RESULTS: During AOP, no significant changes were observed in any of the respiratory variables measured. The change in the apnea-hypopnea index at one month with AOP was +0.2 (95 percent confidence interval, -2.7 to +2.3; P=0.87). In contrast, all variables improved significantly after one month of n-CPAP (change in the apnea-hypopnea index, -46.3; 95 percent confidence interval, -56.2 to -36.5; P<0.001). CONCLUSIONS: Nasal continuous positive airway pressure therapy is highly effective for the treatment of the obstructive sleep apnea-hypopnea syndrome, whereas AOP has no significant effect.

Adult↗
PubMed2005

Correlation of plasma N-terminal pro-brain natriuretic peptide levels with left ventricle mass in children treated with anthracyclines.

BACKGROUND: The incidence of subclinical cardiotoxicity following anthracycline treatment for childhood cancer varies according to the method used for its detection. The aim of the study was to document the prevalence of left ventricular myocardial mass (LVM) reduction and its possible association with plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) levels in asymptomatic children treated with anthracyclines. PATIENTS AND METHODS: Nineteen asymptomatic children who had received anthracyclines during their treatment for cancer were evaluated. They had received an equivalent of doxorubicin dose 240 mg/m2 (22-1200 mg/m2) on average 3.9 years (0.6-8.3) before (median age at diagnosis 3.8 years). The LVM was determined by M-Mode echocardiography and compared to the expected value, obtained from the regression equation of LVM on height of a group of 160 healthy children. Additionally the patients' plasma NT-pro BNP levels were determined. RESULTS: A high prevalence of reduced LVM associated with increased NT-proBNP levels was found. The average LVM value was -14.4% (+/-4.9) lower than expected whereas fourteen patients (73%) had a lower LVM than predicted. The NT-pro BNP levels in patients with reduced LVM were significantly higher than those measured in patients without LVM reduction (0.316+/-0.02 versus 0.17+/-0.01 pmol/ml respectively, p=0.009). A cut off NT-pro BNP level of 0.2 pmol/ml could differentiate patients with LVM reduction from those with normal or greater than expected LVM. CONCLUSION: The association of higher NT-proBNP levels with reduced LVM in asymptomatic children after anthracycline administration could be an early indication of subclinical cardiotoxicity.

Adolescent↗
PubMed2005

Comparative efficacy of nebivolol versus carvedilol on left ventricular function and exercise capacity in patients with nonischemic dilated cardiomyopathy. A 12-month study.

PURPOSE: To compare the efficacy of nebivolol versus carvedilol on left ventricular (LV) function and exercise capacity in patients with nonischemic dilated cardiomyopathy (NIDC). METHODS: After enrollment in this double-blind trial, 72 patients, aged 55 +/- 9.5 years, with NIDC, LV ejection fraction (LVEF) < 45%, New York Heart Association classes II to III, were randomized to either nebivolol (34 patients) or carvedilol (38 patients) and were evaluated through echocardiography and exercise tests at baseline and 3 and 12 months after treatment. RESULTS: During follow-up, 4 patients discontinued nebivolol, although 3 patients stopped carvedilol. Patients in both the nebivolol and carvedilol groups showed a steady improvement in New York Heart Association class (P = .002 and < .001, at 12 months, respectively) and LVEF (P = .001 and < .001, at 12 months, respectively) that became significant from 3-month follow-up on. Intergroup analysis showed that carvedilol group had a greater increase in LVEF at 3 (P = .04) and 12 (P = .02) months' follow-up compared with nebivolol group. Advanced diastolic dysfunction regressed to earlier stages in carvedilol patients after 3 (P = .02) and 12 (P = .01) months' treatment, whereas in the nebivolol group, a significant improvement in diastolic dysfunction was found at the 12 months' follow-up (P = .02). Exercise duration improved in both groups at 12 months' follow-up (both P = .01), but in the nebivolol group, there was an initial deterioration at 3 months (P = .07). CONCLUSIONS: Both nebivolol and carvedilol appear relatively safe, with beneficial effects on LV systolic and diastolic function as well as exercise capacity in patients with NIDC after 12 months' treatment. However, carvedilol exhibits more favorable effects on LV function than does nebivolol.

Benzopyrans↗
PubMed2005

Late left ventricular color M-mode Doppler in the assessment of diastolic dysfunction in patients with dilated cardiomyopathy.

The ratio of early (Ep) to late (Ap) color M-mode Doppler flow propagation through the left ventricle helps in the differentiation between normal and pseudonormal (PSN) filling pattern in patients with preserved systolic function. We studied the value of this index in the assessment of diastolic dysfunction for patients with reduced left ventricular systolic function. We studied 80 patients with nonischemic dilated cardiomyopathy and 50 control subjects. According to echocardiography 53 patients had abnormal relaxation and 27 had PSN pattern. Patients had reduced Ep (P < .001) and Ep/Ap ratio (P < .001) and increased Ap (P = .001) compared to controls. Binary logistic regression analysis showed that Ep followed by Ep/Ap ratio (both P < .001) were the best determinants for the discrimination of PSN from normal filling pattern. Ep/Ap ratio, this novel echo-index, increases the diagnostic accuracy of color M-mode Doppler in discriminating normal from PSN filling pattern in patients with left ventricular systolic dysfunction.

Cardiomyopathy, Dilated↗
PubMed2005

Effects of successful cardioversion of persistent atrial fibrillation on right ventricular refractoriness and repolarization.

AIM: Changes in ventricular refractoriness and repolarization after successful electrical cardioversion to sinus rhythm in persistent atrial fibrillation (AF) patients were studied. METHODS AND RESULTS: In 33 AF patients with controlled ventricular response, right ventricular ERP (VERP) at three basic cycle lengths (600, 500, 400 ms), as well as monophasic action potential duration (MAPd(90)) at a drive cycle length of 500 ms, were measured just before, 20 min and 24 h after cardioversion. VERP at 600 ms changed from 241+/-19 ms to 249+/-21 ms to 253+/-24 ms (P<0.001), VERP at 500 ms changed from 234+/-19 ms to 242+/-22 ms to 246+/-23 ms (P<0.001) and VERP at 400 ms changed from 224+/-20 ms to 232+/-23 ms to 236+/-24 ms (P<0.001). MAPd(90) changed from 247+/-16 ms preconversion to 252+/-17 ms 20 min postconversion to 253+/-19 ms after 24 h (P<0.05). Change in refractoriness at 500 ms was well correlated with change of mean RR interval before and 20 min after conversion (R=0.616, P<0.001). There was no correlation between RR variability and VERP before cardioversion. CONCLUSION: Restoration of sinus rhythm in persistent AF patients is followed by significant effects on ventricular refractoriness and repolarization related to cycle length change. No AF related ventricular electrophysiological alterations were found.

Action Potentials↗
PubMed2005

Peripheral arterial embolism due to a left ventricular diverticulum in a young adult.

A 32-year-old man was admitted to the emergency department of our hospital after experiencing a peripheral arterial embolism. Investigation of the possible embolic sources in an otherwise asymptomatic patient revealed the existence of a left ventricular diverticulum. The left ventricular diverticulum is a rare congenital anomaly, either isolated or as a part of a syndrome including other congenital malformations. The treatment of choice, especially in symptomatic patients, is surgical resection, while in asymptomatic patients anticoagulation therapy is indicated.

Adult↗
PubMed2005

Acute electrophysiologic effects of inhaled salbutamol in humans.

STUDY OBJECTIVES: Although inhaled beta2-agonists are in widespread use, several reports question their potential arrhythmogenic effects. The purpose of this study was to evaluate the cardiac electrophysiologic effects of a single, regular dose of an inhaled beta2-agonist in humans. DESIGN: Prospective study. SETTING: Tertiary referral center. PATIENTS: Six patients with bronchial asthma and 12 patients with mild COPD. INTERVENTIONS: All patients underwent an electrophysiologic study before and after the administration of salbutamol solution (5 mg in a single dose). MEASUREMENTS AND RESULTS: Sinus cycle length, sinus node recovery time (SNRT), interval from the earliest reproducible rapid deflection of the atrial electrogram in the His bundle recording to the onset of the His deflection (AH), interval from the His deflection to the onset of ventricular depolarization (HV), Wenckebach cycle length (WCL), atrial effective refractory period (AERP), and ventricular effective refractory period (VERP) were evaluated just before and 30 min after the scheduled intervention. Salbutamol, a selective beta2-agonist, administered by nebulizer had significant electrophysiologic effects on the atrium, nodes, and ventricle. The AH length decreased from 86.1 +/- 19.5 ms at baseline to 78.8 +/- 18.4 ms (p < 0.001), and the WCL decreased from 354.4 +/- 44.2 to 336.6 +/- 41.7 ms (p = 0.001). Salbutamol significantly decreased the AERP and VERP too while leaving the HV unchanged. Additionally, inhaled salbutamol increased heart rate (from 75.5 +/- 12.8 beats/min at baseline to 93.1 +/- 16 beats/min, p < 0.001) and shortened the SNRT (from 1,073.5 +/- 178.7 to 925.2 +/- 204.9 ms, p = 0.001). CONCLUSION: Inhaled salbutamol results in significant changes of cardiac electrophysiologic properties. Salbutamol enhances atrioventricular (AV) nodal conduction and decreases AV nodal, atrial, and ventricular refractoriness in addition to its positive chronotropic effects. These alterations could contribute to the generation of spontaneous arrhythmias.

Administration, Inhalation↗
PubMed2005

Amino-terminal pro-brain natriuretic peptide predicts ventricular arrhythmogenesis in patients with ischemic cardiomyopathy and implantable cardioverter-defibrillators.

STUDY OBJECTIVES: Even in high-risk population groups, not all patients have the same risk of sudden cardiac death (SCD). Given the emerging data about the amino-terminal fragment of the brain natriuretic peptide prohormone (NT-proBNP) value in heart failure, we planned to evaluate the importance of NT-proBNP levels in predicting the occurrence of malignant arrhythmias in patients with ischemic cardiomyopathy and implantable cardioverter-defibrillators (ICDs). DESIGN: Prospective study. SETTING: Tertiary referral center. PATIENTS: Thirty five ambulatory patients with previous myocardial infarction, left ventricular ejection fraction < 35%, and ICDs for primary prevention of SCD according to Multicenter Automatic Defibrillator Implantation Trial I criteria. INTERVENTIONS: Venous blood samples for plasma NT-proBNP measurement were obtained after 30 min of supine rest from all patients at the beginning of the study. Patients were evaluated every 2 months, or sooner in cases of device discharges, during a 1-year follow-up period. Data concerning arrhythmias and device therapy were stored at the time of device interrogation on each follow-up visit. MEASUREMENTS AND RESULTS: During 1-year follow-up, 11 of 35 patients (31.4%) received 18 antiarrhythmic device therapies for ventricular tachyarrhythmia (VT). Patients who experienced such arrhythmias had NT-proBNP levels of 997.27 +/- 335.14 pmol/L (mean +/- SD), whereas those without VT had NT-proBNP levels of 654.87 +/- 237.87 pmol/L (p = 0.001). An NT-proBNP cutoff value of 880 pmol/L had a sensitivity of 73%, a specificity of 88%, a positive predictive value of 80%, and a negative predictive value of 88% for the prediction of occurrence-sustained VT events. CONCLUSION: To achieve the maximum benefit by ICD therapy, more precise risk stratification is required, even in high-risk, post-myocardial infarction patients. Plasma NT-proBNP levels comprise a promising method that could help in the better identification of a patient group with an even higher risk of sudden death.

Adult↗