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Biomedical subjects

T Vecsey

Publications and source records attributed to T Vecsey.

At least 19 recordsLinked to original sources
PubMed1998

Presence of immunoreactive endothelin-1 and atrial natriuretic peptide in human pericardial fluid.

This study was undertaken to characterize endothelin-1 (ET-1) and atrial natriuretic peptide (ANP) concentrations in human pericardial fluid, blood plasma, right atrial appendage and papillary muscle by use of specific radioimmunoassays. In patients undergoing cardiac surgery (n=16) pericardial fluid mean immunoreactive (ir-) ET-1 and ir-ANP levels were 36-fold and 4-fold higher than corresponding plasma levels, respectively. In high performance liquid chromatography (HPLC) pericardial fluid ir-ET-1 was indistinguishable from human ET-1[1-21] and the majority of pericardial fluid ir-ANP coeluted with human ANP[99-126]. Atrial tissue ir-ET-1 and ir-ANP concentrations were 17-fold and 870-fold higher than in ventricular tissue. Our present study demonstrated for the first time the presence of ir-ET-1 in the pericardial fluid in humans. Human pericardial fluid contained far the highest concentrations of ET-1 among all biological fluids tested thus far. The functions of pericardial fluid ET-1 and ANP on cardiac performance and coronary vascular tone require further investigations.

Adult↗
PubMed1998

Mechanism of endothelin-induced malignant ventricular arrhythmias in dogs.

The development of ventricular tachyarrhythmias caused by low-dose intracoronary infusion of endothelin-1 (ET-1) has recently been observed in dogs. The aim of the present study was to investigate the pathomechanism of ET-1-induced ventricular arrhythmias in 32 anesthetized, open-chest mongrel dogs in group A (n = 14) without, in group B (n = 14), and in group C (n = 4 control) with atrioventricular node ablation. The coronary blood flow (CBF) was measured in the left anterior descending (LAD) coronary artery by an electromagnetic flowmeter. Standard ECG, atrial and ventricular electrograms, and in groups B and C endocardial and epicardial monophasic action potentials (MAPs) were recorded. ET-1 was administered into the LAD at a low dose (30-60 pmol/min). At the time of the appearance of premature beats, CBF was only slightly decreased. The effective ventricular refractory period did not change significantly. Onset of spontaneous polymorphic and monomorphic sustained ventricular tachycardia (sVT) was observed in five dogs without bradycardia and in nine dogs with bradycardia. VTs in dogs with complete AV block were longer and slower. In most of the cases, ventricular fibrillation occurred. ET-1 treatment resulted in a significant increase in MAP 90% duration (255 +/- 9 vs. 290 +/- 8 ms endocardial, 244 +/- 10 vs. 292 +/- 12 epicardial; p < 0.05) at 70 beats/min ventricular pacing. In eight cases (group B), third-phase early afterdepolarization could be recorded. According to our results, the mechanism of ET-1-induced arrhythmias appears to be based on prolongation of MAP duration and development of afterdepolarizations.

Action Potentials↗
PubMed1998

Electrophysiological effects of intrapericardial infusion of endothelin-1.

Recently, extremely high levels of endothelin-1 (ET-1) were detected in the pericardial fluid of patients undergoing open-heart surgery. ET-1 has been suggested to have direct arrhythmogenic effect on myocardium. The aim of the present study was to examine the putative arrhythmogenic effect of intrapericardial infusion of ET-1 in anesthetized dogs (n = 15). In preliminary experiments, ET-1 (0.125-1.0 nmol/min, n = 7) was infused into the closed pericardial sack for 40 min. ET-1 induced non-sustained and/or sustained ventricular tachyarrhythmias in all but the lowest dose. For detailed arrhythmia analysis in addition to standard ECG ventricular endocardial and epicardial monophasic action potentials (MAP) were recorded. ET-1 (0.250 nmol/min, n = 7) induced mono- and polymorphic ventricular tachycardias, which degenerated into ventricular fibrillation in two instances. Moderate if any ischemic signs could be detected before the onset of arrhythmias. The arrhythmias spontaneously disappeared in all instances with the exception when ventricular fibrillation terminated the experiment. QT interval (260 +/- 23 ms vs. 317 +/- 31 ms, P < 0.05), and endo- and epicardial MAPD90 (at 300 ms cycle length) prolonged significantly (in average 182 +/- 12 ms vs. 224 +/- 25 ms, P < 0.05). Using MAP recording afterdepolarizations were detected in three instances. In control animals (n = 3) arrhythmias were not observed and all electrophysiological parameters remained unchanged. The present results show that intrapericardial administration of ET-1 can induce ventricular arrhythmias in dogs. The arrhythmogenic effect of ET-1 may be based on prolongation of MAP duration and development of afterdepolarizations. However, the elucidation of the precise mechanism needs further investigation.

Action Potentials↗
PubMed1998

Simultaneous recordings of the monophasic action potential with silver chloride- and Ir-coated electrodes.

Ag/AgCl and Ir-coated electrodes allow the recording of the monophasic action potential (MAP) due to their electrical properties like non-polarisability. This study investigates the correlation of MAP recorded with both types of electrodes. In 20 mongrel dogs (18 +/- 6 kg) an Ag/AgCl and an Ir-coated catheter (Ir) were placed endocardially in the apex of the right ventricle. The effects of isoproterenol and verapamil were investigated during spontaneous rhythm and stimulation simultaneously recorded with both types of electrodes in 10 dogs without AV-node ablation. The correlation at different heart rates were investigated in 10 other dogs with complete AV-block. The morphology and amplitudes of MAP were comparable (AgCl: 15 +/- 7 mV; Ir: 13 +/- 8 mV). Following an i.v. bolus of 2 micrograms/kg isoproterenol the spontaneous rate increased (175 +/- 18 to 245 +/- 25 bpm). During stimulation with 250 ms cycle length the duration shortened (MAPd90: AgCl: 160 +/- 11 to 130 +/- 12 ms; Ir: 154 +/- 18 to 128 +/- 15 ms). The alterations reversed after 20 min. An i.v. bolus of 0.2 mg/kg verapamil decreased the spontaneous rate (167 +/- 11 to 104 +/- 23 bpm) and lengthened the MAPd90 (AgCl: 182 +/- 14 to 220 +/- 13 ms; Ir: 174 +/- 16 to 216 +/- 21 ms) at 300 ms stimulation. The correlation between the MAPd90 of both lead types was r = 0.98 during all measurements. Under the effect of beta-agonist and Ca(2+)-antagonist medication MAP showed a strong correlation recorded with both types of electrodes. Thus, both leads allow the recording of MAP but only the Ir-electrodes with their long-term stability are implantable and allows us to control the effects of drugs with implantable devices.

Action Potentials↗
PubMed1996

[Clinical importance of monophasic action potential registration in long QT syndrome].

For more than 30 years, the monophasic action potential has been used as an experimental tool for the study of myocardial repolarisation. With recent improvements in catheter design, the utility of the tool as a means to identify the bases for ventricular arrhythmias in humans has been greatly improved. Abnormalities of repolarisation leading to ventricular arrhythmia formation can be identified and specific pharmacological therapies may be evaluated. The pathomechanism of major arrhythmias (ventricular tachycardia, ventricular fibrillation) occurring in long QT syndrome (LQTS) is not yet fully elucidated. The authors have recorded the monophasic action potentials (MAP) of the right ventricle in three patients with LQTS and with previous episodes of major ventricular arrhythmias. The changes in MAP duration and after depolarisation in response to spontaneous arrhythmias, programmed electrostimulation, atrial pacing and isoproterenol treatment were studied. In all of the three patients the early afterdepolarisation was present, which in two cases exhibited pause-dependent features. Thus in these patients dual chamber pacemaker implantatious were performed. These were the first permanent recordings of MAP during electrophysiological examination in Hungary and also the first evidences that the early afterdepolarisation does play a pathogenic role in the development of idiopathic LQTS. Further evaluation of the technique by cardiac electro-physiologists may improve both the diagnosis and the treatment of ventricular arrhythmias dependent upon afterdepolarisation formation.

Action Potentials↗
PubMed1995

[Experience with a transvenous pacemaker-cardioconverter-defibrillator without subcutaneous patch].

Sudden cardiac death caused by malignant ventricular arrhythmias is one of the main causes of cardiovascular mortality. Implantation of cardioverter-defibrillators has resulted in the reduction of the incidence of sudden cardiac death caused by malignant ventricular arrhythmias from the yearly 10-30% to 1%. For the very first time in Hungary, the authors applied only transvenous lead configuration for automatic cardioverter defibrillators in three patients. The indications of the implantation were ventricular fibrillation in one case, ventricular tachycardias refractory to drug treatment in two cases. Ventricular arrhythmias were secondary to coronary heart disease in two patients, dilatative cardiomyopathy in one patient. Preoperative, intraoperative and postoperative electrophysiological studies were regularly taken. Using Biotronik Phylax 03 device with a right ventricular electrode and a superior vena cava electrode and without subcutaneous patch the intraoperative defibrillation thresholds were 6, 11 and 12 J respectively. The fractally iridium coating increases the surface of the electrodes that has a very good effect on defibrillation threshold. During a mean follow-up of six months the occurring spontaneous ventricular arrhythmias (1 ventricular fibrillation and 5 ventricular tachycardias) were terminated by Phylax 03 with cardioversion-defibrillation or overdrive stimulation. The authors' results of intraoperative testing and clinical experiences show that the Phylax 03 biphasic system due to low defibrillation thresholds without subcutaneous patch can safely be applied with only transvenous implant technique in patients with major ventricular arrhythmias to prevent sudden cardiac death and to terminate ventricular tachycardia.

Arrhythmias, Cardiac↗
PubMed1995

Doppler echocardiographic evaluation of left ventricular relaxation in patients with coronary artery disease.

The time constant of the left ventricular isovolumic pressure decline (Tc) was determined according to the Weiss equation in 23 patients with chest pain who underwent cardiac catheterization. Out of them 15 patients had significant coronary artery stenosis (CAD). Tc was compared to 21 diastolic Doppler data derived from the transmitral inflow. We could predict the Tc from Doppler data using a stepwise multiple regression model, Tc = (0.072 x A-Vpeak)-(0.387 x A-dect)-(0.137 x E-dect) + 0.050 (r = 0.7493, p < 0.0011 SEE = 0.007 All Doppler data and the predicted Tc were examined among the CAD and the healthy groups, the predicted Tc and E/A ratio indicated the best discriminant functions.

Coronary Disease↗
PubMed1994

Characteristics of long QT with permanent bradycardia.

The study was aimed to investigate the electrophysiological properties of long QT syndrome associated with permanent bradycardia. The investigations were performed in 26 patients suffering from long QT duration (QTC-frequency adapted QT-:484 +/- 34 ms) with permanent, marked bradycardia (heart rate: 42 +/- 7 min-1). Adams Stokes syncopal attack appeared in 12 patients, while in 14 cases ventricular tachycardia attack with syncope could be observed (study group). As control served the data of 30 patients suffering from long lasting marked bradycardia (heart rate: 44 +/- 7 min-1) with normal QT (QTC:420 +/- 28 ms). Each patient was candidate for pacemaker implantation. The following questions were studied: 1. The effect of heart rate on QT duration. The experiments were performed by electrical ventricular stimulation. 2. The effect of sympathetic and parasympathetic-pharmacologic-blockade on QT time. The study was performed under electrical ventricular stimulation by administration of propranolol and atropine. 3. The dispersion of QT time was studied by using electrical heart stimulation and 12 lead ECG recording. Electrophysiological investigations were performed in 14 patients with long QT and permanent bradycardia. On augmentation of the cycle length (bradycardia) the increase in the QT duration was more-out of all proportion-expressed in long QT. On pharmacologic sympathetic blockade in long QT syndrome the QT duration significantly diminished. The QT dispersion was more expressed in patients with prolonged QT interval and on bradycardia the QT dispersion further increased significantly. The irritability of the ventricle was markedly augmented in patients with long QT and bradycardia. Appearance of polymorphous ventricular tachycardia could frequently be observed and could be regularly induced by early ventricular extrastimuli and bradycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

[Experience with the surgical management of constrictive pericarditis].

61 patients were operated on for constrictive pericarditis at the Cardiovascular Surgical Clinic of Semmelweis Medical University in the last 33 years. The average hospital mortality of the surgical pericardiectomy was 4.9%. The final conclusions of this retrospective and follow up study are as follows: pericardiectomy is the method of choice in the treatment of constrictive pericarditis, since it does not has any therapeutic alternative, its hospital mortality is low and it results excellent early and late postoperative functional effects.

Adolescent↗
PubMed1992

Congenital complete heart block associated with QT prolongation.

The coexistence of congenital complete heart block and QT prolongation represents a special type of arrhythmia. The electrophysiological and clinical characteristics of this syndrome were studied in eight patients suffering from congenital AV block and QT prolongation. Data from 22 patients suffering from congenital complete heart block only, served as a control. In the study group, the appearance of a torsade de pointes type of ventricular tachycardia could regularly be observed and the tachycardial attack could usually be provoked by ventricular extrastimuli. The corrected QT time was markedly prolonged; on ventricular stimulation, at higher pacing rates the QT interval shortened, but remained significantly higher than in the control group. Syncopal attacks--with the character of polymorphic tachycardia--appeared in each patient of the study group while occurring in only three patients from the control group. Patients were given pacemaker implants (using a higher pacing rate) and long-term administration of beta-receptor blockers. The outcome was favourable; no ventricular tachycardia or syncopal attack was observed in the follow-up period.

Adolescent↗
PubMed1990

[Examination of the diastolic function of the left ventricle by Doppler echocardiography in coronary disease].

The authors examined the left ventricular diastolic function at rest and in pain-free period in patients with chest pain but without previous myocardial infarction. Two patient group were formed according to the results of coronarography: 15 patients had significant coronary artery stenosis, while the coronarography was negative in case of 11 patients. Four Doppler echocardiographic parameters were taken and their sensitivity, specificity, positive and negative predictive values were determined on the base of the result of the coronarography. The small number of patients allows only preliminary evaluation but the results suggest that the altered diastolic function enhances the probability of the presence of significant coronary artery disease, while a normal diastolic function decreases its probability.

Coronary Disease↗
PubMed1989

[New aspects of the Kearns-Sayre syndrome].

The case report of the 23 years old female with Kearn-Sayre syndrome started about 15 years ago has some special cardiological aspects. By His band ECG the height of III. degree atrioventricular block was located in the atrioventricular node which is in sharp contrast with all former findings localizing the block into or distal to His band. In the pathogenesis of the unexpected block localisation--besides the muscular degeneration accepted generally in KSS--the recent myocardial infarction of the patient could have a causal role. Electronmicroscopical investigation carried out on the biopsy specimen from the right ventricle revealed both the characteristic hallmarks of "generalized mitochondriopathy" and the pathological glycogen accumulation having been published in skeletal muscles before. The mitral valve prolaps diagnosed in the patient has never been mentioned in KSS. Trauma suffered in early childhood might have a pathogenetic role. In discordance with literature steroid treatment of the diabetic patient with KSS didn't result in lactacidosis.

Adult↗
PubMed1989

The effect of atrial dilatation on the genesis of atrial arrhythmias.

The effect of atrial stretching on the genesis of atrial arrhythmias was studied in 26 dogs. Left atrial dilatation was produced by inflation of a balloon catheter. Electrophysiological studies were performed by programmed electrical stimulation of the atrium and ventricle. The irritability of the atrium markedly increased when it was distended and atrial arrhythmias (sustained or non-sustained atrial tachyarrhythmias) could regularly be induced by administration of an early extrastimulus or--more rarely--by atrial burst pacing. In 10 cases spontaneous atrial tachycardia appeared during atrial balloon dilatation. The atrial effective refractory period shortened and the atrial conduction time lengthened on atrial stretching, while other electrical variables (cycle length, sinus node recovery time, atrioventricular conduction time, intraventricular conduction, ventricular refractory period, QT interval) remained unchanged. Atrial balloon dilatation was not accompanied by marked haemodynamic changes, and the left ventricular pressure curve, the contractility of the left ventricle and the central venous pressure did not change significantly on atrial stretching. The experimental data suggest that the atrial dilatation plays an important part in the pathogenesis of atrial arrhythmias.

Animals↗
PubMed1989

Effect of atrial dilatation on the tendency of atrial arrhythmias.

The arrhythmogenic effect of atrial dilatation was studied by electrophysiological investigations carried out on 24 dogs. Atrial distension was evoked by increasing the pressure in the right atrium (12 to 14 mm Hg) or by the balloon dilatation of the left atrium. Programmed electrical stimulation of the heart was used for the electrophysiological investigations. In addition to the superficial ECG leads also atrial and ventricular epicardial electrograms were obtained for the ECG recording. Acute atrial dilatation led to shortening of the atrial refractory period, whereas neither impulse conduction of the heart, nor pacemaker activity of the sinus node exhibited any alteration. Atrial dilatation resulted in pathological atrial irritability, and early or frequent atrial stimulation caused atrial tachycardia of shorter (non sustained) or longer (sustained) duration. Repetitive atrial extrasystoles in response to early stimuli could also frequently be observed during atrial dilatation. The obtained results indicate that atrial dilatation is arrhythmogenic and may lead to the development of atrial tachycardia.

Animals↗
PubMed1989

The effect of sympathetic and parasympathetic activity on QT duration. Clinical study in patients with normal and prolonged QT time.

The effect of parasympathetic and sympathetic pharmacologic blockade (atropine and propranolol) on QT duration was studied in 26 patients. Of this number 17 had a normal QT time, while in 9 patients the QT interval was prolonged (greater than 460 ms). QT time was determined before and after the pharmacologic blockade with sinus rhythm (under a non fixed cycle length) and with atrial pacing (with a fixed cycle length). Atropine administration did not change QT duration significantly. On the effect of beta receptor blockade in normal patients only the corrected QT time shortened, while in long QT syndrome a very pronounced shortening in QT time, independent of the changes in the cycle length, could be observed. In QT prolongation an overactivity in the sympathetic tone can be supposed.

Adult↗