Biomedical subjects

George N Theodorakis

Publications and source records attributed to George N Theodorakis.

12 recordsLinked to original sources

PubMed2007

Ischaemia modified albumin in radiofrequency catheter ablation.

UNLABELLED: Aim Ischaemia modified albumin (IMA) is considered a marker of myocardial ischaemia, in contrast to the biomarkers of myocardial injury [creatine kinase (CK), the MB isoenzyme of CK, and cardiac troponin I (Tn-I)] that are released when cardiac necrosis occurs. Ischaemia modified albumin has been reported to increase following percutaneous coronary intervention and in acute coronary syndromes. We sought to determine whether IMA increases following radiofrequency (RF) ablation. METHODS AND RESULTS: We studied 40 consecutive patients who underwent RF catheter ablation; 20 were men and 20 women and their age was 47 +/- 16 (16-77) years. All patients underwent electrophysiological study and subsequent RF ablation. Peripheral venous samples were collected before the procedure (baseline), immediately after the procedure, 2 h post-procedure and the following day (20 h post-procedure) and assayed for CK, the MB isoenzyme of CK, cardiac Tn-I and IMA. Ischaemia-modified albumin plasma levels did not differ significantly at all four time points, baseline, and following ablation (P = 0.5974), whereas CK, CK-MB, and Tn-I increased significantly at all time points compared with baseline (P < 0.0001). Post-ablation, all but three 3 CK measurements were in the normal range; 14 patients had CK-MB plasma levels above the upper limit of normal; all but one patient had Tn-I elevated. CONCLUSION: The IMA plasma levels do not change significantly following RF ablation, unlike biomarkers of myocardial injury, implying that myocardial necrosis occurs without preceding ischaemia.

Adolescent↗

PubMed2006

Ischemia-modified albumin in relation to exercise stress testing.

OBJECTIVES: We examined whether ischemia-modified albumin (IMA) plasma levels change during exercise stress testing (EST) in patients with known coronary artery disease and whether the induced changes differ between positive and negative exercise tests. BACKGROUND: Ischemia modified albumin is considered a marker of myocardial ischemia and increases after coronary angioplasty and in acute coronary syndromes. METHODS: We studied 40 consecutive patients with established coronary artery disease who underwent EST. Venous samples, for IMA measurement, were collected before the stress test (baseline), at peak exercise, and 60 min after the completion of the exercise test. RESULTS: There was significant difference in the IMA values at the 3 prespecified time points (p = 0.012), whereas there was no interaction between the IMA changes and the result of the stress test, whether positive or negative (p for the interaction term = 0.94). Baseline, peak EST, and post-EST IMA levels were similar in patients with positive and negative exercise tests (p = 0.61). The IMA significantly decreased at peak exercise compared with baseline values in positive (p < 0.0001) and in negative EST (p = 0.012). Moreover, IMA concentration increased 60 min after EST compared with peak-EST values in positive (p < 0.0001) and in negative tests (p = 0.003), returning to pre-EST levels in both groups. CONCLUSIONS: The IMA plasma levels change significantly during exercise testing in patients with coronary artery disease, but there is no difference between positive and negative stress tests; this possibly implies that the observed changes do not reflect myocardial ischemia.

Adult↗

PubMed2006

Fluoxetine vs. propranolol in the treatment of vasovagal syncope: a prospective, randomized, placebo-controlled study.

AIMS: To compare the therapeutic efficacy of placebo, propranolol, and fluoxetine in patients with vasovagal syncope (VVS). METHODS AND RESULTS: Ninety-six consecutive patients with VVS were randomized to treatment with placebo, propranolol, or fluoxetine and followed-up for 6 months. Before and during treatment, they reported their syncopal and presyncopal episodes and graded their well-being, expressed as the general evaluation of life, general activities, and everyday activities (each scaled from 1 = very good to 5 = very bad). Two patients refused follow-up. Among the remaining 94, no difference between groups was observed regarding the distribution of time of vasovagal events (syncopes or presyncopes) during follow-up (log-rank test). No difference was also observed when syncopes and presyncopes were assessed separately. Eighteen patients discontinued therapy. Among the remaining 76 ('on-treatment' analysis), the mean time to a vasovagal episode (syncope or presyncope) was significantly longer in the fluoxetine group when compared with the two other groups (log-rank test, P < 0.05). A significant difference in favour of fluoxetine was also observed regarding presyncopes. The difference between groups regarding the syncope-free period was not significant. During therapy, patients' well-being was improved (decreased) only in the fluoxetine-group (13.4 +/- 0.7 vs. 15.4 +/- 0.9 before treatment, P < 0.01). CONCLUSION: Fluoxetine seems to be equivalent to propranolol and placebo in the treatment of VVS. However, it improves patients' well-being and might be more effective in reducing presyncopes and total vasovagal events in some patients with recurrent VVS.

Adrenergic beta-Antagonists↗

PubMed2006

Primary stenting of an unprotected left main coronary artery total occlusion in a patient with acute myocardial infraction and cardiogenic shock.

Acute total occlusion of the left main coronary artery (LMCA) is a rare angiographic finding with very poor prognosis. We report a case of a 39-year-old man who presented with pulmonary edema and cardiogenic shock due to an acute anterior myocardial infarction. Coronary angiography, which was performed under the support of an intra-aortic balloon pump, revealed total occlusion of the LMCA. Prompt and successful percutaneous transluminal coronary angioplasty with sirolimus-stent deployment in the LMCA allowed for an uneventful recovery and discharge of the patient.

Adult↗

PubMed2006

Antiinflammatory effects of cardiac resynchronization therapy in patients with chronic heart failure.

BACKGROUND: Cardiac resynchronization therapy (CRT) pacing has been proposed as an additional treatment to medical therapy to improve heart failure patients with left ventricular asynchrony. The aim of this study was to evaluate the influence of CRT treatment on proinflammatory cytokines in patients with heart failure. METHODS: Twenty patients, with a mean age 64 +/- 2 years, with severe chronic heart failure NYHA class II-IV (mean ejection fraction 25 +/- 2%), were included in the study. Patients were treated with CRT pacing, after failure of optimal therapy. Blood samples were taken at baseline, 3 months after pacing therapy, and after a subsequent 3-month period of no pacing for the assessment of proinflammatory cytokines TNF-alpha and its receptors (sTNFR-I, sTNFR-II), IL-6, adhesion molecules sICAM-1 and sVCAM-1, and the apoptotic indices sFas and sFas-Ligand. RESULTS: Levels of TNF-alpha, sTNFR-I, and sTNFR-II were reduced at the end of 3 months of CRT therapy and further reduced at the end of the no pacing period (P < 0.05, compared to baseline). Levels of IL-6 also declined after 3 months of CRT pacing (from 8.9 +/- 2.5 pg/mL to 4.7 +/- 1.3 pg/mL, P < 0.05) and this was maintained during the no pacing period (3.9 +/- 1.1 pg/mL P < 0.05 compared to baseline). The adhesion molecule sICAM-1 levels also reduced (from 265 +/- 17 ng/mL to 235 +/- 12, P < 0.05) after 3 months of CRT pacing and remained unchanged at the end of the no pacing period (219 +/- 12 ng/mL, P < 0.05 compared to baseline values). CONCLUSION: Major proinflammatory cytokines and the adhesion molecule sICAM-1 are reduced with CRT therapy and this effect is maintained for at least 3 months after discontinuation of pacing.

Cytokines↗

PubMed2005

The effects of 5-HT4 receptor blockade and stimulation, during six hours of atrial fibrillation.

AIMS: Stimulation of atrial 5-HT4 receptors is associated with arrhythmias. Their blockade prolongs atrial effective refractory period (ERP), following short runs of atrial fibrillation (AF). The role of 5-HT4 receptors during longer periods of AF is unknown. In this study, we investigated the effects of the selective 5-HT4 receptor stimulation and blockade on porcine atria, during 6 h of AF. METHODS: Atrial ERP, monophasic action potential (MAP) duration, time to sinus rhythm restoration (TSRR) and ERP/MAP ratio were assessed in 27 pigs, at baseline and every hour, during 6 h of AF, induced by rapid atrial pacing. Ten animals were used as controls, 10 were administered the selective 5-HT4 antagonist SB203186 and seven were administered the selective 5-HT4 agonist RS67333. RESULTS: During the first few hours of fibrillation, ERP, MAP and TSRR were preserved in SB203186-treated pigs, while they were shortened in controls and RS67333-treated animals. After 6 h of arrhythmia, ERP and MAP were shortened in all three groups, but the decrease was less in SB203186-treated pigs. ERP/MAP ratio increased in controls and RS67333-treated animals, while it remained unchanged in SB203186-treated pigs. Towards the end of the AF period, four of the SB203186-treated pigs developed sustained atrial tachycardia. CONCLUSION: Following short periods of AF, 5-HT4 receptors' blockade protects the porcine atria against ERP and MAP shortening, while their stimulation has the opposite result. This beneficial effect, though, is gradually diminished following longer periods of AF and atrial tachycardia may develop.

Aniline Compounds↗

PubMed2005

Repeated exercise stress testing identifies early and late preconditioning.

BACKGROUND: The warm-up phenomenon has been considered to trigger preconditioning. We investigated whether repeated exercise treadmill tests in humans are capable of inducing adaptation to ischemia by triggering both the early and late phase of preconditioning. METHODS: In 25 consecutive patients with stable coronary artery disease, four repeated treadmill tests were performed. Thirty minutes following the first test (T1) a second one was performed (T2), followed 6 h later by a third test (T3). Twenty-four hours later all patients were subjected to a fourth exercise test (T4). In every fifth patient, simultaneous echocardiographic examination was performed at the time of the exercise tests in an attempt to reveal ischemic abnormalities. RESULTS: At baseline there was no difference between the variables. At ST segment depression >1.5 mm, the rate-pressure product (RPP) was higher in T2 and T4 (231.3+/-17.9 and 232.6+/-15.8 mm Hg s 10(2)) than in T1 and T3 (210+/-17 and 210.2+/-16.7 mm Hg s 10(2)), p<0.001. Additionally, time to the onset of chest pain was longer in T2 and T4 (430.8+/-60.5 and 438+/-47 s) than in T1 and T3 (345.6+/-69 and 345.6+/-58 s), p<0.001. At peak exercise, the RPP was higher in T2 and T4 (278.6+/-21.6 and 278.3+/-19.6 mm Hg s 10(2)) than in T1 and T3 (255.6+/-23.1 and 256.6+/-23 mm Hg s 10(2)), p<0.001. The wall motion score index was higher in T1 and T3 (1.65+/-0.17 and 1.53+/-0.16) than in T2 and T4 (1.3+/-0.07 and 1.37+/-0.1), p<0.001. CONCLUSION: By using repeated exercise treadmill tests both the early and late phase of protection can be obtained.

Aged↗

PubMed2004

Superior vena cava syndrome and syncope in an implantable cardioverter defibrillator recipient.

We describe the case of a recipient of an implantable cardioverter defibrillator with multiple syncopal episodes due both to superior vena cava obstruction and electrical instability. These complications occurred in the presence of two transvenous implantable cardioverter defibrillator leads. The patient has been managed conservatively with anticoagulants and new antiarrhythmic drugs with improvement in both his clinical problems.

Defibrillators, Implantable↗

PubMed2004

Situational syncope: response to head-up tilt testing and follow-up: comparison with vasovagal syncope.

Among sequential patients with neurally-mediated syncope, we studied the response to head-up tilt test (HUTT) in patients with situational syncope (SS) and their follow-up. Our findings were compared to those in patients with vasovagal syncope (VVS). The response to HUTT in patients with SS has not to date been fully investigated. Additionally, the prognosis of SS patients has not been systematically studied. We studied 162 consecutive patients with recurrent SS or VVS, all free of structural heart disease. Before study inclusion, they underwent an HUTT and were followed up for 12 months. Patients with SS were advised to avoid the trigger event. Patients with VVS were treated with propranolol or fluoxetine. For each patient we compared the number of syncopal spells during the last 12 months before study inclusion with that during follow-up. Among the 162 patients, 36 had SS and 126 had VVS. The response to HUTT and the number of syncopes before and during follow-up were similar in both groups. Among patients with SS, 10 (28%) had also experienced occasional episodes of VVS; however, they had a similar response to HUTT and prognosis to the remaining 26 SS patients without VVS attacks. Patients with SS have a similar response to HUTT and similarly benign clinical course to patients with VVS. The coexistence of occasional VVS episodes in patients with SS is not associated with a higher rate of positive HUTT or worse prognosis.

Adult↗

PubMed2003

Effect of biventricular pacing on heart rate variability in patients with chronic heart failure.

BACKGROUND: Biventricular pacing is emerging as a long-term therapy for symptomatic heart failure. Analysis of heart rate variability (HRV) has become an important predictive tool in this syndrome. AIM OF THE STUDY: To assess whether chronic resynchronization therapy can affect HRV in patients with heart failure. METHODS AND RESULTS: Thirteen patients with heart failure were studied (mean age+/-1 S.E. 65+/-2.2 years, QRS 195+/-5.3 ms, NYHA class 3.2+/-0.1, LVEF 21+/-1.7%). The protocol included a preliminary no pacing period for 1 month following device implantation. Twenty-four hour Holter ECG recordings were performed at the end of this period (baseline) and after 3 months of biventricular stimulation (VDD mode). Prior to and following pacing patients underwent NYHA class evaluation, 6-min walk test, Quality of Life Assessment and a cardiopulmonary exercise test. Biventricular pacing improved functional class (P<0.0001) and Quality of life (P<0.0001), increased 6-min walk distance, (P=0.008) and exercise duration (P<0.0001) but had no significant effect on peak exercise VO(2). Resynchronization therapy increased mean 24-h RR (922+/-58 vs. 809+/-41 ms at baseline, P=0.006), SDNN (111+/-11 vs. 83+/-8 ms, P=0.003), SDNN-I (56+/-10 vs. 40+/-5 ms, P=0.02), rMSSD (66+/-14 vs. 41+/-8 ms, P=0.003), Total Power (5724+/-1875 vs. 2074+/-553 ms(2), P=0.03), Ultra Low Frequency Power (1969+/-789 vs. 653+/-405 ms(2), P=0.03) and Very Low Frequency Power (2407+/-561 vs. 902+/-155 ms(2), P=0.004). CONCLUSION: Biventricular pacing in heart failure improves autonomic function by increasing HRV. This may have important prognostic implications.

Aged↗

PubMed2002

Vasovagal syncope: a prospective, randomized, crossover evaluation of the effect of propranolol, nadolol and placebo on syncope recurrence and patients' well-being.

OBJECTIVES: We sought to assess the relative therapeutic efficacy of propranolol, nadolol and placebo in recurrent vasovagal syncope (VVS). BACKGROUND: Central and peripheral mechanisms have been implicated in the pathogenesis of VVS. Propranolol, nadolol and placebo have different sites of action on central and/or peripheral mechanisms. It has not yet been clarified whether one of the aforementioned treatments is more efficient than the others in reducing clinical episodes and exerting a beneficial effect on patients' well-being. METHODS: We studied 30 consecutive patients with recurrent VVS and a positive head-up tilt test. All were serially and randomly assigned to propranolol, nadolol or placebo. Therapy with each drug lasted three months. On the day of drug crossover, patients reported the total number of syncopal and presyncopal attacks during the previous period. They also gave a general assessment of their quality of life, taking into account: 1) symptom recurrence; 2) drug side effects; and 3) their personal well-being during therapy (scale 0 to 4: 0 = very bad/discontinuation; 1 = bad; 2 = good; 3 = very good; 4 = excellent). At the end of the nine-month follow-up period, they reported whether they preferred a specific treatment over the others. RESULTS: Spontaneous syncopal and presyncopal episode recurrence during each three-month follow-up period was reduced by all drugs tested (analysis of variance [ANOVA]: chi-square = 67.4, p < 0.0001 for syncopal attacks; chi-square = 60.1, p < 0.0001 for presyncopal attacks) No differences were observed in the recurrence of syncope and presyncope among the three drugs. All drugs improved the patients' well-being (ANOVA: chi-square = 61.9, p < 0.0001). CONCLUSIONS: Propranolol, nadolol and placebo are equally effective treatments in VVS, as demonstrated by a reduction in the recurrence of syncope and presyncope, as well as an improvement in the patients' well-being.

Adrenergic beta-Antagonists↗

PubMed2002

Baroreflexes in vasovagal syncope: two types of abnormal response.

Heart rate changes to hypotensive stimuli (baroreceptor sensitivity [BRS]) and forearm blood flow (FBF) reduction during head-up tilt are mediated by arterial and cardiopulmonary baroreceptors. Regarding baroreflexes in neurocardiogenic syncope (NCS), an apparent variation exists in findings reported in the literature. This may be due to the existence of different types of response. This study included 39 patients with NCS and positive tilt test and 26 normal subjects with negative test. Patients were grouped according to the type of tilt test response (mixed, cardioinhibitory, vasodepressor). BRS was noninvasively assessed in the supine position as an estimate of arterial baroreceptor sensitivity. As an estimate of cardiopulmonary baroreceptor reactivity, FBF was measured by venous occlusion plethysmography in the supine position and every 2.5 minutes during the first 15 minutes of tilt. BRS was related to percent of FBF changes. BRS was impaired in syncopal patients relative to controls (7.2 +/- 0.9 vs 10.4 +/- 0.3 ms/mmHg, P = 0.01), especially in vasodepressive type (4.9 +/- 1.0 ms/mmHg, P = 0.0001). FBF changes during tilt were subnormal in NCS, ascribed to two different patterns: one, characterized by impaired vasoconstriction (FBF during tilt showing < 10% mean reduction relative to baseline, especially in vasodepressive type) and another, characterized by a great variability across time (unstable response, especially in cardioinhibitory type). In controls, BRS was related to the percent of FBF changes after 2.5, 5, and 10 minutes of tilt (P values 0.0001, 0.004, and 0.008). In patients, BRS was uncoupled from FBF changes. In conclusion, baroreflexes in NCS are impaired, unstable, and disorganized. Impairment predominates in the vasodepressive type and instability in the cardioinhibitory. The results of this study are indicative of more than one baroreflex-mediated response types.

Adult↗