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(Circulation. 2004;110:2773.)
© 2004 American Heart Association, Inc.
Issue Highlights |
ACUTE ß-BLOCKADE INCREASES MUSCLE SYMPATHETIC ACTIVITY AND MODIFIES ITS FREQUENCY DISTRIBUTION, by Cogliati et al.
The acute administration of ß-blocker leads to a paradoxical increase in postganglionic muscle sympathetic activity (MSNA). However, as with many dynamic physiological systems, the net effect of sympathetic activity on vasomotor tone depends on factors other than the amplitude of MSNA. This study in normal humans examined the effect of ß-blockade with atenolol on the spectral frequency characteristics of MSNA. Despite an increase in MSNA amplitude with atenolol, there was a shift in the frequency distribution, which, the authors suggest, may have led to a decrease in the efficiency of sympathetic vasomotor coupling blockade. See p 2786.
FROM MOUSE TO WHALE: A UNIVERSAL SCALING RELATION FOR THE PR INTERVAL OF THE ELECTROCARDIOGRAM OF MAMMALS, by Noujaim et al.
Mammalian hearts have evolved to optimize coordinated contraction for optimal function using essentially the same structural components from mice to whales. The delay between atrial and ventricular contraction imposed by the conduction times from sinus node, through the atria, AV node, and His bundle is a crucial component of cardiac function. This study of PR intervals in 541 mammals from 33 different species demonstrates that a mathematical relation exists between the PR interval and body mass, which follows a fundamental property of biological scaling. See p 2802.
ASCORBIC ACID PREVENTS CONTRAST-MEDIATED NEPHROPATHY IN PATIENTS WITH RENAL DYSFUNCTION UNDERGOING CORONARY ANGIOGRAPHY OR INTERVENTION, by Spargias et al.
Contrast-induced nephropathy remains a daunting complication both of diagnostic and interventional angiography. Despite its considerable impact on patient morbidity and healthcare expenditures, few effective treatments for this problem exist. In this issue, Spargias and colleagues report a clever study in which ordinary vitamin C was used as a simple and effective prophylactic treatment for contrast-induced nephropathy. This study has the potential to both change clinical practice and reduce healthcare expenditures. See p 2837.
Visit www.circ.ahajournals.org:
Clinician Update
Heparin-Induced Thrombocytopenia: Diagnosis and Management. See p e454.
Images in Cardiovascular Medicine
Drug-Induced Long-QT Syndrome With Macroscopic T-Wave Alternans. See p e459.
Untreated Tetralogy of Fallot With Pulmonary Atresia in a 55-Year-Old Woman: Findings From Magnetic Resonance Imaging. See p e461.
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Related Articles:
Circulation 2004 110: 2786-2791.
Circulation 2004 110: 2837-2842.
Circulation 2004 110: 2802-2808.
Circulation 2004 110: e454-e458.
Circulation 2004 110: e459-e460.
Circulation 2004 110: e461-e462.
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