Making Sense of the ECG

249 Pages·2020·7.303 MB·English

by  Andrew R Houghton

of the
ECG
A hands-on guide
Fifth edition
Andrew R Houghton
Consultant Cardiologist at
United Lincolnshire Hospitals NHS Trust
and Visiting Fellow, University of Lincoln,
Lincolnshire, UK
Boca Raton London New York
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Contents
Preface to the fifth edition vii
Acknowledgements ix
Author xi
1 Anatomy and physiology 1
Cardiac activation 2
The cardiac conduction system 3
The cardiac cycle 4
Further reading 5
2 PQRST: Where the waves come from 7
What does the ECG actually record? 7
How does the ECG ‘look’ at the heart? 8
Where do each of the waves come from? 11
Further reading 18
3 Performing an ECG recording 19
Initial preparations 19
Placement of the limb electrodes 20
Placement of the chest (precordial) electrodes 21
Einthoven’s triangle 22
Recording the 12-lead ECG 25
Further reading 27
4 Reporting an ECG recording 29
Patient data 29
Technical data 29
ECG fundamentals 30
ECG details 30
Report summary 30
Further reading 31
5 Heart rate 33
Is the heart rate below 60/min? 35
Is the heart rate above 100/min? 36
Further reading 39
6 An approach to heart rhythms 41
Identifying the cardiac rhythm 42
How is the patient? 43
Is ventricular activity present? 44
What is the ventricular rate? 44
Is the ventricular rhythm regular or irregular? 44
Is the QRS complex width normal or broad? 45
Is atrial activity present? 47
How are atrial activity and ventricular activity related? 47
iii
iv Contents
Determining the cardiac rhythm 47
Further reading 48
7 Supraventricular rhythms 49
Sinus rhythm 49
Sinus arrhythmia 50
Sinus bradycardia 50
Sinus tachycardia 51
Sick sinus syndrome 52
Atrial ectopic beats 53
Atrial fibrillation 54
Atrial flutter 59
Atrial tachycardia 61
AV re-entry tachycardia 62
AV nodal re-entry tachycardia 67
Further reading 70
8 Ventricular rhythms 71
Ventricular ectopic beats 71
Accelerated idioventricular rhythm 74
Monomorphic ventricular tachycardia 75
How do I distinguish between VT and SVT? 78
Polymorphic ventricular tachycardia 80
Fascicular ventricular tachycardia 81
Ventricular fibrillation 81
Further reading 83
9 Conduction problems 85
Conduction block at the SA node 85
Conduction block at the AV node or bundle of His 85
Conduction block at the bundle branches 88
Conduction block at the fascicles 93
Escape rhythms 93
Accelerated conduction and accessory pathways 94
Further reading 95
10 The axis 97
Understanding and measuring the QRS axis 97
Is there left axis deviation? 106
Is there right axis deviation? 108
Is there extreme right axis deviation? 110
Further reading 110
11 The P wave 111
Are any P waves absent? 111
Are any P waves inverted? 114
Are any P waves too tall? 115
Are any P waves too wide? 116
Further reading 117
12 The PR interval 119
Is the PR interval less than 0.12 s long? 120
Is the PR interval more than 0.2 s long? 122
Does the PR interval vary or can it not be measured? 123
Contents v
Is the PR segment elevated or depressed? 127
Further reading 129
13 The Q wave 131
Are there any ‘pathological’ Q waves? 131
Further reading 136
14 The QRS complex 137
Are any R or S waves too big? 137
Are the QRS complexes too small? 142
Are any QRS complexes too wide? 145
Are any QRS complexes an abnormal shape? 148
Are epsilon waves present? 150
Further reading 152
15 The ST segment 153
Are the ST segments elevated? 153
Are the ST segments depressed? 166
Are J waves present? 170
Further reading 172
16 The T wave 173
Are the T waves too tall? 174
Are the T waves too small? 176
Are any of the T waves inverted? 177
Further reading 182
17 The QT interval 183
Correcting the QT interval 184
Is the QTc interval long? 185
Is the QTc interval short? 188
Further reading 191
18 The U wave 193
Do the U waves appear too prominent? 194
Are any of the U waves inverted? 195
Further reading 196
19 Artefacts on the ECG 197
Electrode misplacement 197
External electrical interference 197
Incorrect calibration 198
Incorrect paper speed 199
Patient movement 199
Further reading 201
20 ECG interpretation in athletes 203
Normal ECG findings 203
Abnormal ECG findings 206
‘Borderline’ ECG findings 206
Further reading 207
21 Pacemakers and implantable cardioverter-defibrillators 209
What do pacemakers do? 209
Indications for temporary pacing 210
vi Contents
Temporary pacemaker insertion and care 210
Indications for permanent pacing 210
Selection of a permanent pacemaker 211
Pacing and the ECG 212
Pacemakers and surgery 214
Implantable cardioverter-defibrillators 214
Cardiac resynchronization therapy (biventricular pacing) 215
Further reading 215
22 Ambulatory ECG recording 217
24-h ambulatory ECG recording 218
Event recorder 218
ECG ‘on demand’ 219
Bedside monitoring/telemetry (inpatient) 219
Insertable cardiac monitor (ICM) 220
External loop recorder (ELR) 220
Smartphone/smartwatch applications 220
Further reading 221
23 Exercise ECG testing 223
What are the indications for an exercise ECG? 223
What are the risks of an exercise ECG? 224
How do I perform an exercise ECG? 225
When do I stop an exercise ECG? 226
How do I interpret an exercise ECG? 226
Further reading 228
Appendix 1: Glossary 229
Appendix 2: ECG resources 233
Appendix 3: Help with the next edition 235
Index 237
Preface to the fifth edition
The primary aim of this fifth edition of Making Sense of the ECG remains the same as all its predecessors –
to provide the reader with a comprehensive yet readable introduction to electrocardiogram (ECG)
interpretation, supplemented by clinical information about how to act upon your findings.
Each chapter has been revised and updated, incorporating current guidelines and research. The text has
been clarified and/or expanded where necessary, new ECGs have been included, and the references and
suggestions for further reading at the end of each chapter have been updated throughout.
A new chapter has been added on ECG interpretation in athletes, with reference to the latest guidelines in
this field. New material has been included on Brugada syndrome and on ECG findings in arrhythmogenic
right ventricular cardiomyopathy. A glossary of ECG terminology has also been added as an appendix.
Once again, I am grateful to everyone who has taken the time to comment on the text and provide ECGs
from their collections. Finally, I would like to thank all the staff at CRC Press who have contributed to the
success of the Making Sense series of books.
Andrew R Houghton
2019
vii
Acknowledgements
I would like to thank everyone who provided suggestions and constructive criticism during the preparation
of each edition of Making Sense of the ECG. I am particularly grateful to the following for their invaluable
comments on the text and for allowing me to use ECGs from their collections:
Mookhter Ajij Lawrence Green V B S Naidu
Richard Andrews Mahesh Harishchandra Vicky Nelmes
Khin Maung Aye Michael Holmes Claire Poole
Stephanie Baker Tim Jones George B Pradhan
Michael Bamber Safiy Karim Jane Robinson
Sophie Beech Dave Kendall Alun Roebuck
Muneer Ahmad Bhat Jeffrey Khoo Catherine Scott
Gabriella Captur Daniel Law Penelope R Sensky
Andrea Charman Diane Lunn Neville Smith
Nigel Dewey Iain Lyburn Gary Spiers
Matthew Donnelly Sonia Lyburn Andrew Staniforth
Simon Dubrey Martin Melville Andrew Stein
Chris Eggett Cara Mercer Robin Touquet
Ian Ferrer Yuji Murakawa Upul Wijayawardhana
Catherine Goult Francis Murgatroyd Bernadette Williamson
I am grateful to the Resuscitation Council (UK) for its permission to reproduce algorithms from its adult
Advanced Life Support guidelines (2015). I also wish to thank the BMJ Publishing Group Ltd, Elsevier, John
Wiley & Sons Australia Ltd and Wolters Kluwer Health Inc for granting permission to use material from
their publications.
Finally, I would like to express my gratitude to Dr David Gray for all his hard work and commitment in
co-authoring the first four editions of this textbook, and to Dr Joanna Koster and the rest of the publishing
team at CRC Press for their encouragement, guidance and support during this project.
ix
Author
Dr Andrew R Houghton studied Medicine at the University of Oxford and undertook postgraduate training
in cardiology in Nottingham and Leicester. He has also trained at Stanford University in California and at
the Mayo Clinic in Minnesota. He was appointed as a Consultant Cardiologist at the United Lincolnshire
Hospitals NHS Trust, UK, in 2002, and is also a Visiting Fellow at the University of Lincoln. His subspecialty
interest is in cardiac imaging (echocardiography and cardiac MRI). He is a Fellow of the European Society
of Cardiology and of the Royal College of Physicians (London).
xi