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      Digitalis: Reappraisal of its Use after Acute Myocardial Infarction

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          Abstract

          Digitalis is a potent inhibitor of sarcolemmal sodium (Na<sup>+</sup>), potassium (K<sup>+</sup>)-ATPase, and, through this property, effects net movement of calcium (Ca<sup>++</sup>) into the myocardial cell. Augmented contractility probably directly results from increased concentrations of activator Ca<sup>++</sup> available to the contractile elements. The clinical manifestations of digitalis toxicity are due to intracellular K<sup>+</sup> depletion, which is an obligatory consequence of Na<sup>+</sup>, K<sup>+</sup>-ATPase inhibition.Digitalis, as a positive inotropic agent, also augments myocardial energy consumption in the nonfailing heart. However, when digitalis is employed in the enlarged, failing heart, a simultaneous reduction in the intramyocardial tension leaves net myocardial oxygen balance unchanged or improved. Digitalis has no unique effect on myocardial energy metabolism. Digitalis acutely increases peripheral vascular resistance in man. Through sympathetically mediated responses, digitalis dilates peripheral blood vessels in patients with heart failure. The direct action of digitalis on the coronary vascular bed is uncertain. In ischemic heart muscle, digitalis can improve contractility, but at a metabolic price. The extent to which myocardial energy balance is affected depends on the simultaneous effect of digitalis on all determinants of myocardial oxygen consumption. Similarly, the hemodynamic changes effected by digitalis are not completely predictable because of many variables changing simultaneously, but generally reflect improved ventricular function. Studies in the dog indicate that the cardiovascular response to digitalis after myocardial infarction is a function of the particular time it is administered during recovery. Initial insensitivity is regained within one weeks’ time. Acute intravenous injections of digitalis in patients with myocardial infarctions may increase after load, thus offsetting the anticipated increase in stroke volume due to the change in contractility alone.The use of digitalis after uncomplicated myocardial infarctions is not recommended. Patients with clinical evidence of heart failure are likely to benefit from digitalis. The larger the heart size and the greater the time passed after the acute infarction when digitalis is administered, the better will be the response. No data presently available clearly demonstrate the efficacy of digitalis in patients with cardiogenic shock.

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          Author and article information

          Journal
          CRD
          Cardiology
          10.1159/issn.0008-6312
          Cardiology
          S. Karger AG
          0008-6312
          1421-9751
          1974
          1974
          29 October 2008
          : 59
          : 1
          : 1-20
          Affiliations
          Cardiology Sections, Flower & Fifth Avenue Hospitals, New York, N.Y., and Northern Westchester Hospital, Mt. Kisco, N.Y.
          Article
          169659 Cardiology 1974;59:1–20
          10.1159/000169659
          4279003
          © 1974 S. Karger AG, Basel

          Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

          Page count
          Pages: 20
          Categories
          Editorial Review

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