Interpreting ECGs in Clinical Practice

119 Pages·2018·9.129 MB·English

by  Sercan Okutucu, Ali Oto

In Clinical Practice
Sercan Okutucu
Ali Oto
Interpreting
ECGs in
Clinical
Practice
In Clinical Practice
Taking a practical approach to clinical medicine, this series of
smaller reference books is designed for the trainee physician,
primary care physician, nurse practitioner and other general
medical professionals to understand each topic covered. The
coverage is comprehensive but concise and is designed to act
as a primary reference tool for subjects across the field of
medicine.
More information about this series at http://www.springer.
com/series/13483
Sercan Okutucu • Ali Oto
Interpreting ECGs
in Clinical Practice
Sercan Okutucu Ali Oto
Department of Cardiology Department of Cardiology
Memorial Ankara Hospital Memorial Ankara Hospital
Ankara Ankara
Turkey Turkey
In Clinical Practice
ISSN 2199-6652 ISSN 2199-6660 (electronic)
ISBN 978-3-319-90556-3 ISBN 978-3-319-90557-0 (eBook)
https://doi.org/10.1007/978-3-319-90557-0
Library of Congress Control Number: 2018943841
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Preface
Electrocardiography has been a very useful clinical diagnos-
tic tool for more than a century. It has been a first step after
clinical evaluation of the cardiac patients and in many situa-
tions for non-cardiac patients as it is widely available, easy to
reach, of low cost and reproducible. To learn how to read the
ECG however is a challenge and one should start from the
basics and relentlessly review large number of ECGs to make
the best use of it.
This book has been prepared for the medical students,
physicians in training and allied professionals who would like
to begin learning ECG. The format is to start with a short
explanation of the basics of ECG and the ABC of “How to
read an ECG?” followed by the typical real-life examples for
the most frequently encountered situations. The ECG trac-
ings are kept as they are; therefore, the reader will see the
tracings as they will meet in their practice. This small book is
designed to be carried in the pocket as an everyday reference
and easy to reach. A short explanation is provided for each
ECG example. However, for further details any textbook can
be used. At the end ECG case studies are added for self-
assessment; brief explanations are also provided to increase
benefits.
As a final note we express our gratitude to those who gave
energy and efforts into this book from the digital arrange-
ment to printing.
Ankara, Turkey Sercan Okutucu
Ankara, Turkey Ali Oto
March 2018
Contents
1 Fundamentals of ECG....................... 1
1.1 Basics for ECG Interpretation ............ 1
References................................. 18
2 E CG Rhythm Interpretation ................. 19
2.1 Normal Rhythm and Arrhythmia.......... 19
References................................. 42
3 E CG in Conduction Disturbances............. 45
3.1 Normal Electrical Conduction
and Disturbances........................ 45
References................................. 55
4 E CG in Cardiac Chamber Enlargement........ 57
4.1 Cardiac Chamber Enlargement ........... 57
References................................. 63
5 E CG in Coronary Artery Disease............. 65
5.1 ECG Changes in Spectrum of Coronary
Artery Disease ......................... 65
References................................. 75
6 E CG in Miscellaneous Conditions ............ 77
6.1 Acute Pericarditis ....................... 77
6.2 Electrolyte Abnormalities ................ 80
6.3 Drug Effects and Miscellaneous Situations.. 83
References................................. 89
viii Contents
7 Eponymous ECGs.......................... 91
7.1 Eponymous ECG Concepts............... 91
References................................. 96
Appendix .................................... 99
ECG Cases ................................ 99
Index ........................................ 113
Chapter 1
Fundamentals of ECG
1.1 Basics for ECG Interpretation
Electrocardiography (ECG) is the process of recording the
electrical activity of the heart over a period using electrodes
placed on the skin. These electrodes detect the subtle electri-
cal changes on the skin that arise from the heart muscle’s
electrophysiologic pattern of depolarization and repolariza-
tion during each heartbeat [1, 2].
The electrocardiograph defines one electrode as exploring
(positive) and the other as reference (negative) electrode. A
vector heading towards the exploring electrode yields a posi-
tive wave/deflection and vice versa (Fig. 1.1).
The ECG waves are recorded on special ECG paper that
is divided into 1 mm2 grid-like boxes. The ECG paper speed
is ordinarily 25 mm/s. As a result, each 1 mm (small) horizon-
tal box corresponds to 0.04 s (40 ms), with dark lines forming
larger boxes that include five small boxes and hence repre-
sent 0.20 s (200 ms) intervals (Fig. 1.2).
On occasion, the paper speed is increased to 50 mm/s to
better define waveforms. In this situation, the heart rate
appears to be one-half of what is recorded at 25 mm/s, and all
the ECG intervals are twice with respect to standard record-
ing. Other paper speeds are occasionally used. Vertically, the
ECG graph measures the height (amplitude) of a given wave
© Springer International Publishing AG, part of Springer 1
Nature 2018
S. Okutucu, A. Oto, Interpreting ECGs in Clinical Practice,
In Clinical Practice, https://doi.org/10.1007/978-3-319-90557-0_1
2 Chapter 1. Fundamentals of ECG
Reference Exploring
electrode electrode Electrical vector is oriented towards the
ECG exploring electrode and therefore
causes a positive deflection.
– Vector +
Reference Exploring
electrode electrode Electrical vector is oriented away from
ECG the exploring electrode therefore
– Vector + causes a negative deflection.
Figure 1.1 ECG Acquisition of electrical signal in different vectors
with opposite orientation is shown
1 mm = 5 mm =
0.04 s 0.2 s
10 mm =
1.0 mV
1 mm =
0.1 mV
Figure 1.2 ECG tracings are recorded on grid paper. The horizontal
axis of the ECG paper records time, each large block equals 0.2 s.
The vertical axis records ECG amplitude (voltage). Two large blocks
equal 1 millivolt (mV). Each small block equals 0.1 mV