Cardiology
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Octogenarians are the fastest growing segment of the population and little is known about the results of cardiopulmonary resuscitation (CPR) after in-hospital cardiac arrest in this population. ⋯ In comparison with other life-saving strategies, CPR in octogenarians is effective. The favorable cost-effectiveness ratio is highly dependent on the patients' preference for quality rather than quantity of life, as expressed by the utility assumptions.
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Cellular mechanisms of adenosine include a direct effect on the activation of the adenosine-sensitive potassium current (I(K,Ado)) and an indirect effect on antagonism of catecholamine-stimulated adenylate cyclase activity. However, previous studies evaluating the influence of catecholamine activity on the electrophysiologic effects of adenosine have yielded conflicting results. We tested the hypotheses that if adenosine exerts its atrioventricular (AV) nodal blocking effects directly by activating the I(K,Ado) potassium current, rather than indirectly by reversing the catecholamine effects, then pretreatment with beta-adrenergic blockade would not potentiate the effects of adenosine in terminating AV nodal-dependent supraventricular tachycardia (SVT). ⋯ Intravenous esmolol infusion (up to 100 mg total dose) usually fails to terminate AV nodal-dependent SVT. In the esmolol-resistant tachycardia, esmolol pretreatment does not produce a positive synergistic effect on the efficacy of adenosine-induced termination of SVT. Therefore, in this tachycardia adenosine may exert its effects on AV nodal conduction directly by activation of the I(K,Ado) potassium current, rather than by antagonizing the beta-adrenergic system.
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Fluid overload is common before, during and after cardiac surgery. The fluid associated with cardiopulmonary bypass (CPB) and cardioplegia is a particularly important source of such fluid overload. In addition, renal dysfunction, which is common in these patients, participates in the pathogenesis of a positive sodium and water balance. ⋯ However, in many patients, diuretics do not achieve sufficient sodium and water diuresis. In these patients, the application of hemofiltration (HF) during CPB and also immediately after CPB is an effective and safe approach to the maintenance of fluid homeostasis. If acute renal failure occurs, early intervention with HF may even improve survival.
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Comparative Study
Autonomic patterns preceding and following accelerated idioventricular rhythm in acute myocardial infarction.
We have investigated the potential relationship between cardiac autonomic activity and accelerated idioventricular rhythm (AIVR) in response to reperfusion in the setting of an acute myocardial infarction (AMI) through spectral analysis of heart rate variability (HRV). ⋯ Our results indicate that reperfusion-induced AIVR is modulated by sympathetic stimulatory effects, whereas a counterregulatory vagal response seems to exert a profound effect upon its suppression. Clinically, the occurrence of early sustained AIVR appears to offer reliable information about both timely reperfusion and sustained and effective coronary artery patency.