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Theory and Interpretation Second Edition

Springer PS1151 ^M

Twelve-Lead Electrocardiography

Second Edition

D. Bruce Foster

Twelve-Lead Electrocardiography

Theory and Interpretation

Second Edition

Springer

D. Bruce Foster, DO

Department of Emergency Medicine

Waynesboro Hospital and

Pennsylvania Institute of Applied Health Sciences

Waynesboro, PA, 17268

British Library Cataloguing in Publication Data Foster, D. Bruce, 1945-

Twelve-lead electrocardiography : theory and interpretation. - 2nd ed. 1. Electrocardiography

I. Title II. Foster, D. Bruce, 1945-. Twelve-lead electrocardiography for ACLS providers 616.1'2'07547 ISBN-13: 9781846285929 ISBN-10: 1846285925

Library of Congress Control Number: 2006932407

ISBN-10: 1-84628-592-5 e-ISBN-10: 1-84628-610-7

ISBN-13: 978-1-84628-592-9 e-ISBN-13: 978-1-84628-610-0

Printed on acid-free paper © Springer-Verlag London Limited 2007

Originally Published as Twelve-Lead Electrocardiography for ACLS Providers, WB Saunders, Co., 1996. ISBN 0721658733.

Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency. Enquiries concerning reproduction outside those terms should be sent to the publishers.

The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant laws and regulations and therefore free for general use.

Product liability: The publisher can give no guarantee for information about drug dosage and application thereof contained in this book. In every individual case the respective user must check its accuracy by consulting other pharmaceutical literature.

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Springer Science+Business Media springer.com

To those delightful little souls who daily make me smile: Mckenzie, Lleyton, Alexa, and Olivia.

Foreword

If you are a cardiologist or have a photographic memory, you may not need Dr. Foster's new book. But, for the rest of us on the front lines of emergency care, it is a valuable resource that you will want to have by your side at work. I have had the first edition of this book by my station in the emergency department for ten years now. I use it everyday for teaching house staff and often turn to it for reference myself.

For those of us without perfect memories, Dr. Foster's clinical approach is ideal. He has the knack of making the complex simple. He does not expect the reader to memorize every squiggle on the page; instead he inspires understanding by giving readers the tools they need to comprehend why ECGs look the way they do. When a resident comes to me with an ECG, I do not have to spend ten minutes delivering a confusing explanation. I just open Dr. Foster's book to the right page and hand it to the resident for review.

The book is organized so that you can turn to the relevant chapter and instantly know what the differential diagnosis might be. His selection of case studies covers the vast majority of the ECGs you will be called on to read in any sort of emergent situation; anything else can wait for the cardiologist.

This second edition features some extensively revised new chapters that make it even more useful than the first. Three very clinical chapters, in particular, offer a roadmap to your daily practice. Chapter 9 gives an excellent summary of the pitfalls that can plague a physician in diagnosing infarctions. Chapter 10 provides a concise, coherent review of anginal syndromes that makes it possible for the novice to catch on quickly. And the case presentations in Chapter 14 offer a spectrum of fascinating real-life clinical scenarios that help you to integrate the ECG into daily clinical practice and structure your approach to acute coronary syndromes. They also serve to show us all why an ECG is but one of the many clues that must ultimately be synthesized into an accurate diagnosis.

Mark L. Feldman, MD Supervising Physician Emergency Department Whangarei Base Hospital Whangarei, New Zealand

Preface

Ten years have passed since Twelve Lead Electrocardiography for ACLS Providers was written in response to a need for a clear, concise, introductory level text on the morphologic interpretation of electrocardiograms. This need has grown more compelling in the last decade, as a multiplicity of efficacious therapeutic interventions has made the early recognition of acute coronary syndromes ever more important. The text was developed primarily for physicians, physicians' assistants, nurses, and paramedics who are advanced cardiac life support (ACLS) certified and are already familiar with cardiac dysrhythmias. Therefore, the text deals solely with morphology and does not discuss dysrhythmias.

The need for the first edition was initially spurred by the revolutionary development in the 1980s of thrombolytic therapy for acute myocardial infarction (AMI), and, subsequently, the evolution of percutaneous coronary intervention. The availability of these tools, and their time dependency, has magnified the critical role of first responders and primary care providers in the early recognition and treatment of AMI.

The clinical chapters in this second edition have been extensively rewritten to reflect new concepts in the clinical classification of patients with chest pain, including acute coronary syndrome, and ST and non-ST-segment elevation myocardial infarction. Sections have been added on the diagnosis of AMI in patients with bundle branch block (BBB), and the case presentations have been expanded and updated to better reflect contemporary practice. Additional illustrations and new references have been incorporated.

I have tried to include all of the pertinent information that ACLS providers working in EMS systems, primary care centers, emergency departments, and critical care units will need to know to implement chest pain evaluation protocols and, hopefully, to speed coronary intervention.

In reality, however, the text has proven to be equally valuable to medical students and non-critical care physicians who need a working knowledge of the important fundamentals of morphologic electrocardiography, but who need not become professional electrocardiographers. Thus, the text emphasizes simplicity, clinically useful concepts, and common clinical parlance. It is written in a conversational tone, and is not intended to serve as a reference text for serious postgraduate students of electrocardiography.

Nevertheless, fundamental electrophysiologic principles are emphasized to the extent that students have the opportunity to deduce patterns created by both physiologic and pathologic processes, rather than relying on memorizing electrocardiographic (ECG) patterns of disease. I have tried to communicate the sense of joy that comes from deduction and understanding, as opposed to the drudgery of memorization.

There are many people who played an important role in the writing of this text, primary among whom are the many students who have instructed me in what works and what doesn't over 15 years of teaching electrocardiogra-phy. This second edition is my thanks for the joy they have shared with me in learning.

And finally, special thanks go, again, to Lauren Datcher, R.N., whose eagle eyes never fail to defect virtually every one of my ubiquitous manuscript errors.

D. Bruce Foster, DO

Contents

Foreword by Mark L. Feldman vii

Preface ix

1 Essential Cardiac Anatomy and Physiology as It Relates to the Electrocardiogram 1

2 Electrocardiographic Waveforms 5

3 Cardiac Vectors and Lead Systems 12

4 Derivation of the Normal Electrocardiogram 17

5 Electrical Axis 24

6 Intraventricular Conduction Delays: The Hemiblocks 34

7 Intraventricular Conduction Delays: The Bundle Branch Blocks 42

8 Chamber Enlargement 57

9 Myocardial Infarction 64

10 Ischemia and Anginal Syndromes 84

11 The Electrocardiogram and the Clinical Evaluation of

Chest Pain 94

12 The Advanced Cardiac Life Support Provider and Therapeutic Interventions in Acute Myocardial Infarction 101

13 Miscellaneous Conditions 116

14 Case Presentations 125

Index 165

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