Fundamental electrophysiological differences between low-dose intracoronary endothelin-1 infusion and myocardial ischemia revealed by multiple monophasic action potential recording.

The supposed direct arrhythmogenic property of endothelin-1 (ET-1) has not yet been clearly proven. Our study aimed to characterize the electrophysiological changes during left anterior descending artery (LAD) occlusion and intracoronary (i.c.

Investigating the dual nature of endothelin-1: ischemia or direct arrhythmogenic effect?

Endothelin-1 (ET-1) is a potent vasoconstrictor peptide, which may also elicit severe ventricular arrhythmias. The aims of our study were to compare the effects of total left anterior descending coronary artery (LAD) occlusion to intracoronary (ic.) ET-1 administration and to investigate the pathomechanism of ET-1 induced arrhythmias in 3 groups of anesthetized, open-chest mongrel dogs.

Intrapericardial infusion of endothelin-1 induces ventricular arrhythmias in dogs.

Objectives: Recently, extremely high levels of endothelin-1 (ET-1) were detected in the pericardial fluid of patients with heart disease; however, the pathophysiological importance of this finding is not known. The present study was designed to characterize ET-1 levels in canine pericardial fluid and to investigate the effects of local high concentrations of exogenous ET-1 in vivo.

Methods: In anesthetized, open-chest dogs ET-1 (Groups 1 and 2: 11 and 33 pmol.

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.

Bradycardia increases the arrhythmogenic effect of endothelin.

The effect of permanent bradycardia on the proarrhythmic action of endothelin-1 (ET) was investigated in 24 open-chest anesthetized mongrel dogs. In 12 dogs, permanent bradycardia was induced by radiofrequency ablation of the AV node and the hearts were paced at 70 beats/min. ET (60 pmol/min) was infused into the left anterior descending coronary artery.

Potential pathophysiologic role of endothelin-1 in canine pericardial fluid.

Recently, extremely high levels of endothelin-1 (ET-1) were detected in the pericardial fluid of patients undergoing cardiac surgery. This study was designed to assess the pathophysiologic importance of this finding by infusing ET-1 into the closed pericardial sac of anesthetized dogs. Systemic arterial blood pressure, heart rate, and standard ECG were recorded.

Verapamil reduces the arrhythmogenic effect of endothelin.

In a previous study we established that endothelin-1 (ET-1) can induce characteristic ventricular tachycardias (VT) with significant prolongation of QT and QTc time. In this investigation we studied the role of CA2+ channels in the pro-arrhythmic effects of ET-1. In 24 anesthetized, open-chest mongrel dogs, ET-1 was administered into the left anterior descending coronary artery at a comparatively low dose (60 pmol/min) for 30 min.

[Intermittent Romano-Ward syndrome].

Two cases are described to have intermittent long QT syndrome. This type of long QT syndrome is not easy to recognize and the result could be fatal in case taking I/A type antiarrhythmic drugs. The first patient who was investigated had got "chinidin syncope" two years earlier, the second one had symptoms of syncope and dizziness for 3 months.

[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.

[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.

Ventricular tachycardias induced by intracoronary administration of endothelin-1 in dogs.

In 12 anesthetized, open-chest mongrel dogs, endothelin-1 (ET-1) was infused into the left anterior descending coronary artery through an indwelling catheter at a dose of 30 pmol.min-1 for 30 min (n = 8). In four dogs the ET-1 dose was increased to 60 pmol/min for 10 min.

Coronary arteriopathy after lymphatic blockade: an experimental study in dogs.

The effects of lymph stasis on the histological and biochemical properties of the coronary arterial wall and on the coronary circulation were studied in 72 dogs. Cardiac lymph stasis was produced in 52 dogs by cardiac lymphatic blockade whereas in 20 dogs only a sham operation was performed. Blockade of cardiac lymph drainage promoted characteristic injury to the coronary arteries including subendothelial edema with plasma inbibition, interstitial and intracellular edema in the tunica media with degeneration in the smooth muscle layer, swelling of the adventitial space with dilated lymph vessels and, later, fibrosis.

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).

[Iatrogenic sinus node disease and iatrogenic AV block].

The appearance of long lasting bradycardia due to damage of the sinus node (iatrogen sick sinus syndrome; or the atrioventricular conduction system, iatrogen AV block) is not a rare event after open heart surgery. In the course of 5093 heart operations the development of iatrogen sick sinus syndrome was observed in 234 patients (4.6%) and iatrogen AV block in 91 cases (1.

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.

[Regulation of blood circulation in the extremities in intermittent claudication].

Unlabelled: The study was aimed to investigate the characteristics of the limb circulation in patients suffering from intermittent claudication. The study group consisted of 71 patients with intermittent claudication. As control served the data of 60 patients with intact peripheral circulation and 24 patients suffering from rest pain, too.

The effect of atrial dilatation on reperfusion arrhythmias: development of supraventricular tachycardias on reperfusion with atrial stretching.

Unlabelled: The study was aimed at investigating the effect of atrial dilatation on the genesis of supraventricular tachyarrhythmias following myocardial reperfusion. Experiments were carried out in 26 mongrel dogs under pentobarbital narcosis with artificial ventilation. Electrophysiological study was performed for studying the arrhythmic condition of the heart.

Lymphatic arteriopathy: damage to the wall of the canine femoral artery after lymphatic blockade.

The effect of lymph stasis on the histological, biochemical, and elastic properties of the femoral artery were studied after regional lymphatic blockade in 36 dogs. Dogs were sacrificed 4-21 days after operation. Histologic changes of the femoral arterial wall (interstitial edema, degeneration in the muscle layer or media, thickened adventitia with dilated lymph vessels, and fibrosis) developed after regional lymphatic blockade.

The association of carotid artery stenosis with carotid sinus hypersensitivity. Transitory cerebral ischaemic attack provoked by carotid sinus reflex.

The association of internal carotid stenosis with the carotid sinus syndrome represents a special clinical entity. Transitory cerebral ischaemic attack (TIA) will usually be manifested by activation of carotid sinus reflex. Eighteen patients were observed suffering from both carotid sinus hypersensitivity and TIA.

The effects of bisaramil on experimental arrhythmias.

Antiarrhythmic activity of bisaramil (3-methyl,7-ethyl,9 alpha, 4'-(Cl-benzoyloxy)-3,7-diazabicyclo[3.3.1.

Characteristics of the limb circulation in hypertension.

The aim of this study was to investigate the effect of hypertension on the regulation of limb circulation. The study group consisted of 50 patients suffering from hypertension; in 21 cases the peripheral circulation was intact, while 29 patients had peripheral obliterative arterial disease (POAD) (clinical symptoms: intermittent claudication or rest pain). The control group consisted of 67 normotensive patients.

[Changes in the femoral vein in dogs as an effect of experimental lymphedema].

Authors studied changes of femoral vein developed by the effect of examinations experimental lymphoedema in dogs. Light and electronmicroscopic were performed from femoral vein of animals killed on 3rd and 14th postoperative day, and biomechanical examinations were done too from dogs killed on 14th postoperative day. In vessel wall edema, fibrosis, and in valves infiltration consisting of macrophages, neutrophilic granulocytes and of mesenchymal cells were observed.

Atrial standstill: an indication for rate responsive pacing.

Atrial standstill (atrial paralysis) is a rare reason for permanent bradycardia. A case of atrial standstill is presented. A 35-year-old man had suffered from bradycardia since his childhood.

Regulation of circulation in congestive heart failure.

Regulation of extremity (limb) circulation was studied in 21 patients suffering from congestive heart failure. In 11 cases the peripheral circulation was intact, while 10 patients also suffered from peripheral obliterative arterial disease. Data of 75 patients with normal cardiac condition served as control: 35 subjects with intact peripheral circulation and 40 patients suffering from peripheral obliterative arterial disease.

The effect of vasodilator therapy on the limb circulation in hypertension.

The effect of vasodilator drugs on limb circulation was investigated in 59 hypertensive patients. Forty-six of them suffered from obliterative arterial disease, too. The drugs administered were: hydralazine, nitroglycerine and sodium nitroprusside.