Practical ECG for exercise science and sports medicine

179 Pages·2010·13.415 MB·English

by  Gregory P Whyte, Sanjay Sharma, (Professor of inherited cardiac diseases)

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Practical ECG
f o r
Exercise Science
a n d
Sports Medicine
Greg Whyte, PhD, FACSM
Liverpool John Moores University
Sanjay Sharma, BSc, MD, FRCP, FESC
St George’s University of London
Human Kinetics
Library of Congress Cataloging-in-Publication Data
Whyte, Gregory P.
Practical ECG for exercise science and sports medicine / Greg Whyte, Sanjay Sharma.
p. cm.
Includes bibliographical references and index.
ISBN-13: 978-0-7360-8194-8 (soft cover)
ISBN-10: 0-7360-8194-1 (soft cover)
1. Electrocardiography. 2. Exercise tests. 3. Heart--Diseases--Diagnosis. 4. Exercise--Physiological
aspects. I. Sharma, Sanjay. II. Title.
RC683.5.E5W49 2010
616.1'207547--dc22
2010011261
ISBN-10: 0-7360-8194-1 (print)
ISBN-13: 978-0-7360-8194-8 (print)
Copyright © 2010 by Greg Whyte and Sanjay Sharma
All rights reserved. Except for use in a review, the reproduction or utilization of this work in any form or by any
electronic, mechanical, or other means, now known or hereafter invented, including xerography, photocopying, and
recording, and in any information storage and retrieval system, is forbidden without the written permission of the
publisher.
The Web addresses cited in this text were current as of March 12, 2010 unless otherwise noted.
Acquisitions Editors: John Dickinson, Loarn D. Robertson, PhD, and Karalynn Thomson; Developmental Editor:
Kevin Matz; Assistant Editors: Casey A. Gentis and Steven Calderwood; Copyeditor: Patsy Fortney; Indexer:
Bobbi Swanson; Permission Manager: Dalene Reeder; Graphic Designer: Fred Starbird; Graphic Artist: Yvonne
Griffith; Cover Designer: Bob Reuther; Photographer (interior): Photos courtesy of Greg Whyte, unless otherwise
noted; Photo Production Manager: Jason Allen; Art Manager: Kelly Hendren Associate Art Manager: Alan L.
Wilborn; Printer: Versa Press
Printed in the United States of America 10 9 8 7 6 5 4 3 2 1
The paper in this book is certified under a sustainable forestry program.
Human Kinetics
Web site: www.HumanKinetics.com
United States: Human Kinetics Australia: Human Kinetics
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[phone]
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E4777
For Seema, Anushka, and Shivani
Sanjay Sharma
To my wife, Penny, and my precious girls,
Maya and Elise
Greg Whyte

Contents
Preface vii
Part I
Structure and function of the Heart
Chapter 1 The Heart . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Cardiac Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Cardiac Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Electrical Properties of the Heart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Electrocardiography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Contractile Properties of the Heart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Exercise and the Heart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Key Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Chapter 2 Monitoring the Electrical
activity of the Heart . . . . . . . . . . . . . . . . . 19
Palpation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Heart Rate Monitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Electrocardiography at Rest and During Exercise . . . . . . . . . . . . . . . . . . . . 21
Exercise Modalities and Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Ambulatory ECG Monitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Implantable Loop Recorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Key Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Part II
The ECG
Chapter 3 normal ECG at rest . . . . . . . . . . . . . . . . . . 39
Reading the ECG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Interpreting the ECG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Common Mistakes In Preparing and Placing Leads (Troubleshooting) . . . . . . 53
Key Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Chapter 4 abnormal ECG at rest . . . . . . . . . . . . . . . . 55
Bradyarrhythmias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Tachyarrhythmias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Atrial and Ventricular Enlargement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
ECG Abnormalities in Diseases of the Coronary Circulation:
Ischemia and Myocardial Infarction . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Unusual ECG Abnormalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Key Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
v
vi    Contents
Chapter 5 ECG during Exercise . . . . . . . . . . . . . . . . . 97
Normal ECG Responses During and Postexercise . . . . . . . . . . . . . . . . . . . . 98
Evaluation of People With Known or Suspected Exercise-
or Exertion-Related Arrhythmias . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
ECG Exercise Stress Testing
in the Diagnosis of Coronary Artery Disease (CAD) . . . . . . . . . . . . . . . . 105
Key Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Part III
The athlete’s Heart
Chapter 6 The athlete’s Heart:
Physiological Versus Pathological . . . . . 115
Cardiac Structure and Function in Highly Trained Athletes . . . . . . . . . . . . . 116
Electrocardiogram (ECG) of an Athlete . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Arrhythmias and the Athlete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Syncope and the Athlete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Sudden Cardiac Death (SCD) in Athletes . . . . . . . . . . . . . . . . . . . . . . . . . 123
Preparticipation Screening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Key Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Chapter 7 athlete Case Studies . . . . . . . . . . . . . . . . 127
Case Study 1: Spontaneous Atrial Fibrillation in a Freestyle Skier . . . . . . . . . 127
Case Study 2: Exercise-Induced Vasodepressor Syncope in an Elite Rower:
A Treatment Dilemma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Case Study 3: Prevalence and Significance
of an Isolated Long QT Interval in Elite Athletes . . . . . . . . . . . . . . . . . . 132
Case Study 4: Differentiation of RVOT-VT and ARVC in an Elite Athlete . . . . . 139
Case Study 5: Treat the Patient Not the Blood Test: The Implications of an
Elevation in Cardiac Troponin Following Prolonged Endurance Exercise . . 145
Case Study 6: Acute Myocardial Infarction in the Presence
of Normal Coronaries and the Absence of Risk Factors in a Young,
Lifelong Regular Exerciser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
References 153
Index 159
About the Authors 167
Preface
T
he electrocardiogram (ECG) was first troubleshooting common problems. Chapter
described by Einthoven (a Dutch phy- 4 offers an interrogation of normal and abnor-
sician) in the late 19th century. Following mal ECG findings with a detailed examination
the invention of the bipolar limb leads by of cardiac abnormalities. Each abnormality is
Einthoven, Dr. Frank N. Wilson and colleagues accompanied by a sample ECG trace. Chapter
established the six chest leads in the 1930s. 5 focuses on the ECG during exercise. Exer-
That was followed by Dr. Goldberger’s inven- cise creates a unique physiologic situation
tion of the three augmented limb leads. In the that results in a provocative challenge to
subsequent years, ECG has become the most the cardiovascular system. As a result, the
widely used noninvasive tool in the assess- ECG during exercise has become a tool in
ment of cardiac electrical function. The ECG the identification of a variety of pathologies,
offers the opportunity to examine the heart including coronary artery disease, exercise-
to discover information about the electrical induced arrhythmias, and assistance in the
conduction system and its morphology, func- differentiation of pathologic and physiologic
tion, and circulation. Practical ECG for Exercise enlargement of the left ventricle. While the
Science and Sports Medicine is based on our role of the exercise ECG for the identification
experience evidenced by over 100 peer- of myocardial ischemia has been in use for
reviewed papers, multiple books and book decades, a burgeoning understanding of the
chapters, and over a decade of interpreting importance of the exercise ECG in identify-
ECGs from clinical patients to elite athletes ing and differentiating various diseases has
both at rest and during exercise. resulted in an increased use of exercise as
Practical ECG for Exercise Science and a diagnostic tool in cardiology. Chapter 6
Sports Medicine offers an overview for those focuses on athletes’ hearts. The physiologic
unfamiliar with the ECG and a resource for adaptations associated with chronic physical
those working in the field of exercise and training manifest as cardiac enlargement and
sports medicine and science. Featuring more increased thickness of the walls, additional
than 100 ECGs and illustrations, the seven heart sounds on auscultation, sinus brady-
chapters in this text progress from theory cardia, and ECG anomalies. These physi-
to practice. Chapter 1 presents an overview ologic changes may mimic those observed in
of the morphology of both the heart and the pathologic processes, so accurate diagnosis is
electrical conduction system. An examina- required for differentiating a physiologic from
tion of cardiac function at rest and during a pathologic substrate. This is of particular
exercise offers the underlying theory relevant importance for those pathologies that cause
to the interpretation of the ECG. Chapter 2 sudden cardiac death in athletes. An under-
examines methods of monitoring heart rate standing of the anomalies often present in
and rhythm, facilitating an understanding of athletic individuals at rest and during exercise
the breadth of measurement modalities avail- is important for those working in sporting
able. Chapters 3, 4, and 5 examine the ECG in environments. Chapter 7 presents case stud-
detail at rest and during exercise. Chapter 3 ies to highlight the problems encountered in
focuses on obtaining a 12-lead ECG, including dealing with athletes’ hearts.
vii
viii    Preface
Understanding a normal ECG at rest and ECG for Exercise Science and Sports Medicine
during exercise and being able to interpret find- contains timely information for undergraduate
ings are becoming increasingly important for and postgraduate students from a variety of
noncardiologists, including health profession- disciplines. In addition, this book is a valuable
als, sports medicine specialists, physiothera- resource for health professionals working with
pists, clinical exercise physiologists, and sport athletic and sedentary individuals at rest and
and exercise scientists. Accordingly, Practical in exercise stress testing.