Head-up tilt induced syncope and adenosine A2A receptor gene polymorphism.

Aims: High adenosine plasma levels and high expression of adenosine A(2A) receptors are observed in patients with unexplained syncope and a positive head-up tilt test (HUT). This study aimed to evaluate the single nucleotide polymorphism (SNP) (c.1364 T>C) which is the most commonly found polymorphism in the A(2A) receptor gene, in patients with unexplained syncope undergoing HUT.

Peripheral plasma adenosine release in patients with chronic heart failure.

Objective: Chronic heart failure (CHF) is accompanied by increased adenosine plasma levels (APLs). It is unknown whether adenosine release occurs at the peripheral level or whether the myocardium itself is the source of adenosine release. To answer this question, we evaluated APLs in the coronary sinus of CHF patients during a resynchronisation procedure and compared the values with those at the peripheral level.

Release of markers of myocardial damage evaluated in the coronary sinus during cardiac surgery.

Myocardial damage is a frequent complication of cardiac surgery by direct mechanical trauma during the surgical procedure and by myocardial ischemia, which occurs during the cardiopulmonary bypass (CBP). Because the concentrations of biomarkers in the blood collected from the coronary sinus are the best witness of the myocardial damages, we measured the levels of specific cardiac troponin I (c-TnI) and nonspecific (adenosine, myoglobin) markers of left ventricular damages in the coronary sinus of patients during cardiac surgery. Thirty patients who underwent aortic valve replacement for aortic stenosis were included.

Increased expression of adenosine A2A receptors in patients with spontaneous and head-up-tilt-induced syncope.

Background: Adenosine may play a role in the triggering of neurocardiogenic syncope, but no information on adenosine receptors is available at the present time.

Objective: The purpose of this study was to investigate whether adenosine A2A receptors expression is altered in patients with neurocardiogenic syncope.

Methods: Adenosine plasma levels (APLs), the expression of A2A receptors, were measured (mean +/- standard error of the mean) during tilt testing.

Relationship between A2A adenosine receptor expression and intradialytic hypotension during hemodialysis.

Background: Intradialytic hypotension (IDH) is a common complication of hemodialysis sessions (HDSs). Adenosine may contribute to the drop in blood pressure during IDH events because it has hypotensive effects. As A(2A) adenosine receptor expression is essential for blood pressure control, we compared the expression of A(2A) receptors (Bmax, K(D), and messenger ribonucleic acid [mRNA] levels) in peripheral blood mononuclear cells from IDH and non-IDH patients and from controls.

Influence of haemodialysis and left ventricular failure on peripheral A(2A) adenosine receptor expression.

Background: Haemodialysis (HD) sometimes accelerates left ventricular failure (LVF). As adenosine (ADO) is strongly implicated in cardiovascular functions, particularly via A(2A) receptor activation and as changes of peripheral A(2A) receptors mirror changes occurring in the cardiovascular system, we examined the influence of HD and LVF on both ADO plasma concentration and the expression of A(2A) receptors (i.e.

Role of endogenous adenosine as a predictive marker of vasoplegia during cardiopulmonary bypass and postoperative severe systemic inflammatory response.

Objective: Systemic inflammatory response (SIRS) and severe SIRS (SIRS with organ dysfunction) occurring after cardiopulmonary bypass (CPB) are common causes of morbidity and mortality among cardiac surgical patients. These syndromes are often preceded by a profound vasodilation, characterized by vasoplegia occurring during surgery. Many substances have been implicated in their pathophysiology.

Intra-atrial thrombosis and pulmonary embolism complicating pacemaker leads for cardiac resynchronization therapy.

This is the first report of intracardiac thrombi and pulmonary embolism complicating pacemaker leads implanted for cardiac resynchronization therapy. Prompt diagnosis and successful therapy with a thrombolytic agent lead to a favourable outcome. This report suggests that long-term oral anticoagulation should be considered in patients with depressed left ventricular function undergoing cardiac resynchronization therapy in order to prevent this potentially serious complication.

[Tolerance and efficacy of carvedilol prescription in patients with mild to moderated chronic heart failure].

The current treatment for heart failure, i.e., carvedilol administration, has brought about a significant reduction in cardiovascular morbidity and mortality.

Supraspinal antinociceptive effects of mu and delta agonists involve modulation of adenosine uptake.

Background: The modulation of extracellular adenosine concentration by opioids provides evidence that the antinociceptive effects of these compounds involve endogenous adenosine. The aim of this study was to determine whether there is a relation between the inhibition of brain synaptosome adenosine uptake by opioid agonists and the analgesic effects of these compounds.

Methods: The authors used the hot plate and tail-pinch tests to evaluate in mice (C57BL/6 females; weight, 25-30 g) the effects of caffeine, a nonspecific adenosine receptor antagonist, on the antinociceptive effect induced by the intracerebroventricular administration of oxymorphone as a mu agonist, SNC80 as a delta agonist, or U69593 as a kappa agonist.

Role of endogenous adenosine as a modulator of syncope induced during tilt testing.

Background: Previous reports that used head-up tilt testing and adenosine administration have suggested that adenosine may be an important endogenous mediator that may trigger a vasovagal response in susceptible patients. However, little is known regarding endogenous adenosine plasma levels (APLs) during vasovagal syncope provoked by tilt testing. The aim of this study was to determine whether APLs differ in patients with a positive head-up tilt test compared with those with a negative test and whether APLs are modified during tilt-induced vasovagal syncope.

[Cardioversion by external electric shock for atrial fibrillation: does patient age affect immediate results?].

The restoration of sinus rhythm by external electric shock in patients with persistent atrial fibrillation is a well established treatment. However, in current practice this treatment is generally indicated less in the elderly subject although this attitude is not factual. The objective of this work was to evaluate the immediate results of cardioversion by external electric shock, comparing the success rates in four age groups: under 60 years, between 60 and 69 years, between 70 and 79 years, and over 80 years.

Influence of residual myocardial ischaemia on induced ventricular arrhythmias following a first acute myocardial infarction.

Objectives: The purpose of this study was to assess the possible effect of residual myocardial ischaemia on induced ventricular arrhythmia during programmed ventricular stimulation in survivors of a first acute myocardial infarction.

Background: Most deaths after hospital discharge for acute myocardial infarction are sudden and presumably arrhythmic. Sudden cardiac death results from a dynamic interaction of structural abnormalities and transient triggering factors.

Effects of digoxin on chemoreflex in patients with chronic heart failure.

The effects of digitalis on the baroreflexes in human chronic heart failure have been well studied. Similarly, since it has been recently shown that chemoregulation remains generally effective during cardiac failure, the goal of this study was to evaluate the effects of a chronic administration of digoxin on the chemoreflexes. Hemodynamic and blood gas parameters were assessed in 7 patients with chronic congestive heart failure before and after chronic administration for 10 days of digoxin therapy (0.

Plasma beta-endorphin and adenosine concentration in pulmonary hypertension.

To determine whether beta-endorphin plays a role in the regulation of pulmonary vascular tone in patients with pulmonary hypertension, we investigated the relations between hemodynamics and beta-endorphin and adenosine concentrations in 3 clinical situations: (1) normal hemodynamics (7 subjects, mean pulmonary artery [PA] pressure 18.5 +/- 1 mm Hg); (2) moderate pulmonary hypertension secondary to chronic obstructive pulmonary disease (COPD) (8 patients, mean PA pressure 31 +/- 3 mm Hg); and (3) severe primary pulmonary hypertension (PPH) (8 patients, mean PA pressure 70 +/-5 mm Hg). Plasma beta-endorphin and adenosine were measured in a distal PA and in the femoral artery in room air and during oxygen inhalation.

Effects of percutaneous transluminal coronary angioplasty on coronary adenosine concentrations in humans.

Background: Even minimal amounts of adenosine is released during myocardial ischemia. Its role in coronary blood flow has been extensively studied, but little is known about its behaviour during percutaneous transluminal angioplasty (PTCA) in man.

Material And Methods: Using in situ samples the aim of this study was to evaluate adenosine plasma concentration before and after PTCA.

Adenosine plasma concentration in pulmonary hypertension.

Objective: In this study, we sought to appreciate the role of adenosine in the regulation of pulmonary vascular tone, especially in the case of clinical pulmonary hypertension, by investigating the relationship between endogenous plasma adenosine levels and pulmonary artery vasoconstriction.

Methods: Adenosine plasma concentrations, were measured simultaneously in the distal right pulmonary artery and in the femoral artery, both at steady state (room air) and during pure oxygen inhalation. Three clinical situations were considered: (1) normal hemodynamics [7 control subjects, mean pulmonary artery pressure (MPAP) = 18.

Hemodynamic effects of bilevel nasal positive airway pressure ventilation in patients with heart failure.

Aims: Benefits of nasal continuous positive airway pressure (CPAP) in patients presenting with chronic heart failure (CHF) are controversial. The purpose of this study was to compare the hemodynamic effects of CPAP and bilevel positive airway pressure (BiPAP) in patients with or without CHF.

Methods And Results: Twenty patients with CHF and 7 with normal left ventricular function underwent cardiac catheterization.

Hemodynamic response to oxygen administration in chronic heart failure: role of chemoreflexes.

The aim of this study was to assess whether arterial chemoreceptors are activated in chronic heart failure and to appreciate whether this activation is related to the degree of cardiac dysfunction. We examined whether administration of pure oxygen for 30 min to 35 patients with chronic heart failure was followed by hemodynamic modifications that would suggest a negative feedback (inactivation) of such chemoregulation. A decrease in heart rate and cardiac output was observed in all patients.

Long-term effects of cicletanine on secondary pulmonary hypertension.

Cicletanine, a furopyridine-derivative drug, was shown to enhance the production of endogenous prostacyclin. The potent vasodilating properties of prostacyclin are used to treat severe primary pulmonary hypertension. Prostacyclin has a short half-life and can be administered only as an i.

Effect of almitrine bismesylate on pulmonary vasoreactivity to hypoxia in chronic obstructive pulmonary disease.

The aim of this double-blind, placebo-controlled study was to determine whether acute administration of almitrine enhances hypoxic pulmonary vasoconstriction in patients with chronic obstructive pulmonary disease (COPD). Haemodynamics and blood gases were studied at various inspiratory fractional concentrations of oxygen (FIO2): 0.15, 0.

[Acute effects of nicardipine on the vascular reactivity of oxygen in patients with respiratory insufficiency and pulmonary hypertension].

Pulmonary vascular response to the inhalation of various concentrations of oxygen (FIO2) was studied under basal conditions and after nicardipine in 10 patients with pulmonary hypertension secondary to chronic bronchitis. Hemodynamic data and blood gases were measured during inhalation of 3 gas mixtures: hypoxia (FIO2 = 0.15), normoxia (FIO2 = 0.

Nifedipine inhibits the effects of almitrine in patients suffering from pulmonary artery hypertension secondary to chronic obstructive pulmonary disease.

It has been suggested that almitrine improves the local ventilation/perfusion ratio by enhancing hypoxic pulmonary vasoconstriction (HVC), leading to an increase in pulmonary vascular resistance (PVR) and PaO2. The goal of the present study was to determine if pulmonary vasodilation induced by nifedipine inhibits the enhancement of HVC (and consequently of PaO2), in patients suffering from chronic obstructive pulmonary disease (COPD). Two groups of 10 patients were compared in a controlled, double-blind study.

Vascular and cardiac reactivity in pulmonary hypertension due to chronic obstructive lung disease: assessment with various oxygen concentrations.

The aim of the present work was to evaluate vasoreactivity in patients with pulmonary hypertension related to chronic obstructive lung disease. This was done by comparing haemodynamic data recorded while patients were breathing room air, and hypoxic and hyperoxic mixtures. We estimated the role of vasoconstriction in determining the level of pulmonary hypertension.