George Karavolias
Athens State University
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Featured researches published by George Karavolias.
Journal of the American College of Cardiology | 2002
Stamatis Adamopoulos; John Parissis; Dimitrios Karatzas; Christos Kroupis; Michael Georgiadis; George Karavolias; John Paraskevaidis; Katerina Koniavitou; Andrew J.S. Coats; Dimitrios Th. Kremastinos
OBJECTIVES We sought to investigate the effects of physical training on circulating proinflammatory cytokines and the soluble apoptosis mediators Fas (sFas) and Fas ligand (sFasL) in patients with chronic heart failure (CHF). BACKGROUND Recent investigations have shown an overexpression of circulating proinflammatory cytokines and soluble apoptosis mediators in patients with CHF, which may be related to their exercise intolerance and clinical deterioration. METHODS Plasma levels of tumor necrosis factor-alpha (TNF-alpha), soluble TNF receptors I and II (sTNF-RI and sTNF-RII, respectively), interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6R), sFas and sFasL were measured in 24 patients with stable CHF (New York Heart Association functional class II/III; left ventricular ejection fraction 23.2 +/- 1.3%) and in 20 normal control subjects before and after a 12-week program of physical training in a randomized, crossover design. Functional status of patients with CHF was evaluated by using a cardiorespiratory exercise test to measure peak oxygen consumption (VO2max). RESULTS Physical training produced a significant reduction in plasma levels of TNF-alpha (7.5 +/- 1.0 pg/ml vs. 4.6 +/- 0.7 pg/ml, p < 0.001), sTNF-RI (3.3 +/- 0.2 ng/ml vs. 2.7 +/- 0.2 ng/ml, p < 0.005), sTNF-RII (2.6 +/- 0.2 ng/ml vs. 2.3 +/- 0.2 ng/ml, p = 0.06), IL-6 (8.3 +/- 1.2 pg/ml vs. 5.9 +/- 0.8 pg/ml, p < 0.005), sIL-6R (34.0 +/- 3.0 ng/ml vs. 29.2 +/- 3.0 ng/ml, p < 0.01), sFas (5.5 +/- 0.7 ng/ml vs. 4.5 +/- 0.8 ng/ml, p = 0.05) and sFasL (34.9 +/- 5.0 pg/ml vs. 25.2 +/- 4.0 pg/ml, p < 0.05), as well as a significant increase in VO2max (16.3 +/- 0.7 ml/kg per min vs. 18.7 +/- 0.8 ml/kg per min, p < 0.001). Good correlations were found between a training-induced increase in VO2max and a training-induced reduction in levels of the proinflammatory cytokine TNF-alpha (r = -0.54, p < 0.01) and the apoptosis inducer sFasL (r = -0.57, p < 0.005) in patients with CHF. In contrast, no significant difference in circulating cytokines and apoptotic markers was found with physical training in normal subjects. CONCLUSIONS Physical training reduces plasma levels of proinflammatory cytokines and the sFas/sFasL system in patients with CHF. These immunomodulatory effects may be related to the training-induced improvement in functional status of patients with CHF.
Heart | 2006
Efstathios K. Iliodromitis; Stamatis Kyrzopoulos; Ioannis Paraskevaidis; Kyriacos Kolocassides; Stamatis Adamopoulos; George Karavolias; Dimitrios Th. Kremastinos
Aim: To investigate whether remote ischaemic preconditioning (RIPC) can attenuate the inflammatory response and enzyme leakage that can occur after uncomplicated routine percutaneous coronary intervention (PCI). Methods: 41 consecutive normotensive patients with stable angina and single-vessel disease were assigned to be exposed to RIPC (n = 20) or not (control group; n = 21) before elective PCI with stent implantation. RIPC was induced by three cycles of 5-min ischaemia–reperfusion of both upper limbs (inflation/deflation of blood pressure cuff). C reactive protein (CRP), creatine phosphokinase (CK), CK cardiac isoenzyme (CK-MB) and troponin I (TNI) were serially measured for 48 h. Results: No difference in baseline values was observed between the groups. The CRP rose significantly (p<0.001) and at 48 h was similarly increased (>fourfold) in both groups (15.7 (2.6) v 14.0 (3.3) mg/l, RIPC v control; p = NS). However, sub-group analysis on the basis of statin use showed that the highest rise was in the group of patients with RIPC not taking statins and was significantly greater than in patients with RIPC taking statins (23.8 (3.71) v 11.4 (3.0) mg/l, respectively, p<0.01). Both CK-MB and TNI leakage were raised (slightly but significantly) after PCI in controls at 24 h compared with baseline values. However, this small rise was significantly worse after RIPC (CK-MB, 1.33 (0.27) v 3.57 (0.97) ng/ml, p<0.01; TNI, 0.255 (0.059) v 0.804 (0.232) ng/ml, p<0.05, respectively at 24 h). The increase was more marked in the RIPC subgroup not taking statins. Conclusions: RIPC does not reduce, but exacerbates, the enzyme and TNI release from the heart after single-vessel angioplasty with stent. Furthermore, the increased circulating CRP remains raised. It seems that there is an enhanced inflammatory response after RIPC in the absence of statin treatment.
The American Journal of Medicine | 2001
Dimitrios Th. Kremastinos; George A Tsetsos; Dimitrios Tsiapras; George Karavolias; Vassilios Ladis; Christos Kattamis
PURPOSE To evaluate the survival of patients with beta thalassemia and heart failure who were treated with iron chelation therapy. SUBJECTS AND METHODS Fifty-two consecutive patients with beta thalassemia and heart failure were followed in a prospective 5-year study. All patients underwent a full clinical examination with chest radiograph, electrocardiogram, and echocardiographic investigation performed at 6-month intervals or when a new symptom developed. RESULTS Of the 52 patients (mean [+/- SD] age, 24 +/- 5 years), 25 (48%) survived 5 years after the onset of heart failure. Forty-three patients had left-sided heart failure, and 9 had right-sided heart failure. Those with left-sided heart failure were younger at presentation with heart failure (22 +/- 4 years vs. 31 +/- 6 years; P <0.001), had lower ejection fractions (36% +/- 9% vs. 64% +/- 10%; P <0.001), and had a lower mean serum ferritin level (3355 +/- 1241 ng/mL vs. 6,397 +/- 1,613 ng/mL; P <0.001). CONCLUSION The 5-year survival rate in patients with beta thalassemia with heart failure was greater than previously reported. There are clinical characteristics that may make patients more likely to develop left- or right-sided heart failure.
European Journal of Haematology | 2005
Sophie Mavrogeni; Vyron Markussis; Loukas Kaklamanis; Dimitrios Tsiapras; Ioannis Paraskevaidis; George Karavolias; Markisia Karagiorga; Marouso Douskou; Dennis V. Cokkinos; Dimitrios Th. Kremastinos
Abstract: Objectives: To apply magnetic resonance imaging (MRI) for the assessment of myocardial iron deposition in patients with β‐thalassemia and compare the results with cardiac biopsy data. Background: Myocardial iron accumulation is the main cause for cardiac complications in β‐thalassemia. Methods: Twenty‐five consecutive thalassemic patients were studied using a 0.5‐T (Tesla) system, ECG‐gated, with echo time (TE) = 17–68 ms. T2 relaxation time of the interventricular septum was calculated assuming simple monoexponential decay. A heart T2 relaxation time value of 32 ms was used for the discrimination between high and low iron deposition. Heart biopsy was performed within a week after the MRI study. Patients with stainable iron in more than 50% of the myofibrils were graded as having severe iron deposition. A serum ferritin level below 2000 ng/mL was considered as an indication of successful chelation. Results: Seven of the 25 patients had heart biopsy indicative of low iron deposition (Group L) and the remaining 18 patients had heart biopsy indicative of high iron deposition (Group H). T2 relaxation time of the heart (T2H) was lower in Group H compared to Group L (31.5 ± 3.9 (range: 28–40) ms vs. 35.7 ± 3.7 (range: 29–40) ms, P = 0.026). The T2H was in agreement with heart biopsy in 86% of the patients in Group L and in 78% of the patients in Group H (overall agreement 80%). Similarly, serum ferritin levels were in agreement with heart biopsy in 28% and 88%, respectively (overall agreement 72%). In Group L, MRI was in better agreement with biopsy compared to serum ferritin (86% vs. 28%, P < 0.05). A receiver operating characteristic curve (ROC) analysis confirmed that a T2 relaxation time of 32 ms had the highest discriminating ability for the corresponding biopsy outcome. Conclusions: Heart T2 relaxation time appears in agreement with cardiac biopsy, both in high and low iron deposition, and may become a useful non‐invasive index in β‐thalassemia.
European Heart Journal | 2003
Stamatis Adamopoulos; John Parissis; Ioannis Paraskevaidis; Dimitrios Karatzas; Efthimios Livanis; Michael Georgiadis; George Karavolias; Dimitrios Mitropoulos; Dimitrios Degiannis; Dimitrios Th. Kremastinos
BACKGROUND Recent experimental and clinical data indicate that abnormal central and peripheral immune reactions contribute to the progression of chronic heart failure, and that immunomodulation may be an important therapeutic approach in this syndrome. Aims We sought to study the effects of growth hormone (GH) administration on circulating pro-inflammatory/anti-inflammatory cytokine balance, and to investigate whether these GH-induced immunomodulatory effects are associated with the improvement of left ventricular (LV) contractile performance in idiopathic dilated cardiomyopathy (DCM) patients. METHODS Plasma pro-inflammatory cytokines tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), granulocyte-macrophage colony-stimulating factor (GM-CSF) and its soluble receptor (sGM-CSFR), chemotactic cytokine macrophage chemoattractant protein-1 (MCP-1), soluble adhesion molecules intercellular adhesion molecule-1 (sICAM-1) and vascular cell adhesion molecule-1 (sVCAM-1), and, finally, anti-inflammatory cytokines interleukin-10 (IL-10) and transforming growth factor-beta2 (TGF-beta2) were measured (ELISA method) in 12 patients with DCM (NYHA class III; LV ejection fraction: 23.6+/-1.7%) before and after a 3-month subcutaneous administration of GH 4IU every other day (randomized crossover design). Peak oxygen uptake (VO2 max), LV dimensions, LV mass index, end-systolic wall stress (ESWS), mean velocity of circumferential fibre shortening (Vcfc), and contractile reserve (change of ratio Vcfc/ESWS after dobutamine administration) were also determined at the same period. RESULTS Treatment with GH produced a significant reduction in plasma TNF-alpha (7.8+/-1.1 vs 5.5+/-0.9pg/ml, P=0.013), IL-6 (5.7+/-0.5 vs 4.7+/-0.4pg/ml, P=0.043), GM-CSF (27.3+/-1.7 vs 23.3+/-1.8pg/ml, P=0.042), sGM-CSFR (4.0+/-0.4 vs 3.2+/-0.4ng/ml, P=0.039), MCP-1 (199+/-5 vs 184+/-6pg/ml, P=0.048), sICAM-1 (324+/-34 vs 274+/-27ng/ml, P=0.008) and sVCAM-1 (1238+/-89 vs 1043+/-77ng/ml, P=0.002) in DCM patients. A significant increase in ratios IL-10/TNF-alpha (1.9+/-0.3 vs 3.5+/-0.9, P=0.049), IL-10/IL-6(2.6+/-0.6 vs 3.2+/-0.5, P=0.044) and TGF-beta2/TNF-alpha (3.1+/-0.6 vs 4.4+/-0.6, P=0.05) was alsofound with GH therapy. A significant reduction in ESWS (841+/-62 vs 634+/-48gr/cm(2), P=0.0026) and LV end-systolic volume index (LVESVI, 128+/-12 vs 102+/-12ml, P=0.035) as well as a significant increase in posterior wall thickness (PWTH, 9.2+/-0.5 vs 10.3+/-0.6mm, P=0.034), contractile reserve (0.00029+/-0.0001 vs 0.00054+/-0.0001circ*cm(2)/gr*s, P=0.00028) and VO2max (15.3+/-0.7 vs 17.1+/-0.9ml/kg/min, P=0.002) were observed after GH administration. Good correlations were found between GH-induced increase in contractile reserve and the increases in VO2max (r=0.63, P=0.028), IL-10/TNF-alpha (r=0.69, P=0.011) and TGF-beta2/TNF-alpha (r=0.58, P=0.046) ratios, as well as the reduction in plasma TNF-alpha levels (r=-0.86, P=0.0004). CONCLUSIONS GH administration modulates beneficially circulating cytokine network and soluble adhesion molecules in patients with DCM, whilst enhancing contractile reserve and diminishing LV volumes. These GH-induced anti-inflammatory effects may be associated with the improvement in LV contractile performance and exercise capacity as well as with the reverse of LV remodelling of patients with DCM.
Atherosclerosis | 2000
Dimitrios Th. Kremastinos; Elias Bofilis; George Karavolias; Apostolos Papalois; Loukas Kaklamanis; Efstathios K. Iliodromitis
BACKGROUND Hypercholesterolemia predisposes to coronary artery disease and causes endothelial dysfunction; some reports suggest that endothelial derived substances are involved in ischemic preconditioning. OBJECTIVE Our aim was to examine the possibility that preconditioning maybe attenuated in a clinically relevant animal model of hypercholesterolemia with atherosclerosis. METHODS Male rabbits were fed with cholesterol enriched diet and then divided into two groups (A and B) without and with preconditioning, respectively. A second series of rabbits fed a normal diet were similarly divided into two groups (C and D) without and with preconditioning, respectively. All the animals were subjected to 30 min ischemia and 180 min reperfusion. Blood samples were collected for cholesterol assessment; arterial and heart samples were harvested at the end for histopathological examination. Infarct (I) and risk areas (R) were delineated with Zn-Cd particles and TTC staining. RESULTS Cholesterol in groups A and B was 58.3+/-8.7 mg% at baseline and 1402+/-125 mg% at 8 weeks (P<0.0001) and in groups C and D 57.5+/-5.8 mg% before the surgical procedure. I/R% was 39. 3+/-6.3% in group A, 16.7+/-3.9% in B (P<0.01), 41.4+/-7.5% in C and 10.8+/-3.3% in D (P<0.01). CONCLUSION We conclude that preconditioning is unlikely to be attenuated by hypercholesterolemia.
Pacing and Clinical Electrophysiology | 1992
George N. Theodorakis; Dimitrios Th. Kremastinos; George T. Avrambos; George S. Stefanakis; George Karavolias; P. Toutouzas
The aim of this study was to assess the heart rate variability in patients with vasovagal syndrome (WS). Heart rate variability was expressed as: (1) the standard deviation (SD) of the mean RR interval; and (2) the SD as a percentage of the mean RR interval (%SD). Heart rate variability was measured in VVS patients and compared with control individuals. Eighteen patients (mean age 50 ± 14 years) with a history of recurrent syncope and positive tilt testing were included in the study. Fifteen asymptomatic individuals (mean age 53 ± 13 years) with no history of syncope and negative tilt testing were used as a control group. The SD and %SD (39 ± 38 and 5 ± 4 msec) in the WS group were statistically higher at the tenth minute of tilt testing than in the control group (20 ± 14 and 2.5 ±1.8 msec, P = 0.03 and P < 0.05, respectively). The mean RR interval (mean heart rate) was shorter after the 15th minute of tilt testing in the WS group than in the control group (RR‐WS 687 ± 136 msec, RR‐control 801 ± 131 msec, P < 0.05). It is concluded that heart rate variability, as expressed by the SD of the mean RR interval, and the SD as a percentage of the mean RR interval (%SD) are significantly higher in VVS patients than in control asymptomatic individuals.
American Journal of Cardiology | 2002
Ioannis Paraskevaidis; Dimitrios Tsiapras; George Karavolias; Philip Cokkinos; Dimitrios Th. Kremastinos
The aim of this study was to analyze the components of mitral and pulmonary A waves and to construct a Doppler-derived left ventricular (LV) end-diastolic pressure (EDP) prediction model based on the combined analysis of transmitral and pulmonary venous flow velocity curves. Combined analysis of transmitral and pulmonary venous flow velocity curves at atrial contraction is a reliable predictor of increased LV filling pressure. The duration of pulmonary and mitral A waves is determined by the sum of respective acceleration and deceleration time. Mitral flow and left upper pulmonary vein flow velocity curves were recorded simultaneously with LVEDP in 40 consecutive patients (aged 59 +/- 8 years) with coronary artery disease and preserved LV systolic function. Differences in all parameters represent values of pulmonary minus those of mitral A wave curve. The difference in deceleration time was the strongest candidate, being included in all models. After redundancy evaluation, we reached the following model: LVEDP = 20.61 + 0.229 x difference in deceleration time (r(2) = 0.80, p <0.001). In the entire study group, the difference in duration and in deceleration time of the A wave was highly correlated with LVEDP (r = 0.79, p <0.001, and r = 0.88, p <0.001, respectively). The entire study group was further divided according to whether LVEDP was above (group I, 20 patients) or below (group II, 20 patients) the median value (15.5 mm Hg). In group I, the difference in duration and in deceleration time correlated well (r = 0.62, p = 0.01, and r = 0.75, p = 0.001, respectively) with LVEDP, whereas in group II only the difference in deceleration time correlated well (r = 0.68, p = 0.005). In patients with coronary artery disease and preserved LV systolic function, the combined analysis of mitral and pulmonary A waves can predict LVEDP. The difference in deceleration time between pulmonary and mitral A waves can reliably evaluate high and normal LVEDP.
Cytokine | 2011
Stamatis Adamopoulos; Fotis Kolokathis; Angeliki Gkouziouta; Panagiota Georgiadou; Antigoni Chaidaroglou; George Karavolias; Dimitrios Degiannis; Vassilis Voudris; Dimitrios Th. Kremastinos
AIMS To identify potential genetic associations of five cytokine gene polymorphisms with disease severity and prognosis in patients with idiopathic dilated cardiomyopathy (DCM). METHODS AND RESULTS Eighty patients with DCM were genotyped for transforming growth factor beta1 (TGF-β1)+869 T/C (codon10 Leu→Pro), TGF-β1 +915 G/C (codon25 Arg→Pro), interleukin (IL)-6 -174G/C, tumor necrosis factor-alpha (TNF-α) -308A/G, interferon-gamma (IFN-γ) +874T/A, IL-10 -1082A/G, IL-10 -819T/C and IL-10 -592A/C gene polymorphisms. In homozygous TT patients for TGF-β1 +869 T/C polymorphism mean VO(2) max was significantly higher than in CC homozygous patients (25.67±6.73ml/kg/min vs. 20.29±6.35 ml/kg/min, p = 0.046), which remained significant only for patients younger than 39 years old after adjusting for age and sex (p = 0.009). C carriers of TGF-β1 +915 G/C polymorphism are 4.2 times more likely to be in a worse NYHA stage (III-IV) than non C carriers [OR: 4.25, 95% CI (1.53-11.80), p = 0.006]. Patients GG homozygous for IL-6 -174G/C polymorphism presented greater left ventricle end-systolic (p = 0.018) and end-diastolic (p = 0.04) diameters in comparison to the CC homozygous. The AA homozygote for IFN-γ +874T/A polymorphism (p = 0.02) and the combination of the TGF-β1 +869 T/C and TGF-β1 +915 G/C genotypes were associated with adverse outcome (p = 0.014). CONCLUSION Specific cytokine gene polymorphisms seem to be associated with worse prognosis as well as with measures of disease severity in DCM.
Pacing and Clinical Electrophysiology | 1990
George N. Theodorakis; Dimitrios Th. Kremastinos; Manolis Markianos Efthimios Livanis; Christos Archontakis; George Karavolias; P. Toutouzas
THEODORAKIS, G., ET AL.: C‐AMP and ANP Levels in VVI and DDD Pacing with Different AV Delays During Daily Activity and Exercise. Nine patients (three males) mean age 68 ± 8 years, having complete heart block, and paced in the DDD mode were examined in VVI and DDD pacing with 100 and 150 ms atrioventricular delays (AVD) during rest and exercise. Plasma atrial natriuretic peptide (ANP) and cyclic AMP (c‐AMP) were measured at rest and at peak exercise test. ANP plasma levels at rest were significantly higher in VVI pacing compared to 150 AVD (p < 0.03). On exercise, ANP release was statistically increased only in DDD with 150 ms AVD, while in WI it remained in high levels at exercise but no significant change was found (p:ns). c‐AMP during rest was unchanged in any pacing mode or AVD, but on exercise DDD pacing with short AVD (100 ms) released lower c‐AMP plasma levels, than at rest (p:ns). DDD pacing with long AVD (150 ms) during exercise produced statistically higher c‐AMP plasma levels (p < 0.05) than at rest. Also in VVI pacing the c‐AMP plasma levels were statistically higher than at rest (p < 0.02). Adrenergic activity seems to be lower during exercise in DDD pacing with shorter AVD (100 ms) than in DDD with 150 ms AVD or VVI pacing. No difference was found in c‐AMP plasma levels at rest. ANP release was also found to be lower at exercise in DDD pacing with short AVD (100 ms) than in DDD with 150 ms AVD. ANP plasma levels at rest were statistically higher in VVI pacing. (PACE, Vol. 13, December, Part II 1990)