ECG for the Small Animal Practitioner

110 Pages·2009·13.579 MB·English

by  Lawrence P Tilley, Naomi L Burtnick

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ECG
for the Small
Animal Practitioner
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Dedication
To my wife Jeri, and my son Kyle,
and to all my students of electrocardiography
for whom this book is written.
Larry Patrick Tilley
To my mother Beryl,
who continues to nurture my independent
spirit and deep love of learning,
and to my brother David,
who shares my delight in figuring out
how things work.
Naomi Lee Burtnick
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VetMed
Dr.LarryP.Tilley & Associates
Suite 279
1704-B Llano Street
Santa Fe, New Mexico, 87505 USA
Telephone: [phone]
Fax: [phone]
Email: [email protected]
Within the United States:
Telephone: [phone]
Fax: [phone]
4
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Preface
We take great satisfaction
in bringing the reader this convenient review of basic canine and
feline electrocardiography. It is our hope that the text will both help
the practicing veterinarian meet his day-to-day needs and stimulate
the interest of students in small animal electrocardiography. We feel
that the conciseness and clarity of this presentation has contributed
immeasurably to these ends.
We also want to acknowledge thanks to Williams and Wilkins
for permission to reuse selected illustrations from my Textbook:
Essentials of Canine and Feline Electrocardiography,Interpretation
and Treatment, 3rd Edition, Lea & Febiger, 1992.
The rapid evolution of animal electrocardiography has made an
easily accessible text such as this both necessary and welcome.
Today’s ECG instruments have placed in the hands of the
veterinarian an accurate and efficient means of recording the
electrical activity of the animal’s heart. But what does the ECG
tracing mean? To own an electrocardiograph is not enough; the
veterinarian must use his ECG instrument correctly and interpret
the ECG recording accurately.
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Table of Contents
1
Section “How To”
Introduction & Helpful Hints . . . . . . . . . . . . . . . . . . . . . . . . 9
Applications of the Electrocardiogram . . . . . . . . . . . . . . . . 10
Circulation System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Conduction System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Five Physiologic Properties of Cardiac Muscle . . . . . . . . . . 13
Electrocardiogram–Definition . . . . . . . . . . . . . . . . . . . . . . . 14
What is a Lead, Anyway? . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Generation of the Electrocardiogram . . . . . . . . . . . . . . . . . 16
Electrocardiographic Recording Technique . . . . . . . . . . . . 17
ECG Paper & Standardization . . . . . . . . . . . . . . . . . . . . . . 19
Calculating the Heart Rate . . . . . . . . . . . . . . . . . . . . . . . . . 20
Measuring the P-QRS-T . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Canine ECG Normal Values . . . . . . . . . . . . . . . . . . . . . . . . 24
Feline ECG Normal Values . . . . . . . . . . . . . . . . . . . . . . . . . 25
Quick & Dirty Guide to ECG Enlargements &
Bundle Branch Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Classification of Arrhythmias . . . . . . . . . . . . . . . . . . . . . . . 27
Building Blocks for Arrhythmia Interpretation . . . . . . . . . 28
Interpreting Arrhythmias–the Easy Way . . . . . . . . . . . . . . . 30
2
Section -Electrocardiographic Examples
Normal Sinus Impulse Formation
Normal Sinus Rhythm . . . . . . . . . . . . . . . . . . . . . . . 34
Sinus Arrhythmia . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Disturbances of Sinus Impulse Formation
Sinus Bradycardia . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Sinus Tachycardia . . . . . . . . . . . . . . . . . . . . . . . . . . 40
6
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Disturbances of Supraventricular
Impulse Formation
Atrial Premature Complexes . . . . . . . . . . . . . . . . . . 44
Atrial Tachycardia . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Atrial Fibrillation . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Atrioventricular(AV)Junctional Premature
Complexes &Tachycardia . . . . . . . . . . . . . . . . . . . . 50
Disturbancesof Ventricular Impulse Formation
Ventricular Premature Complexes . . . . . . . . . . . . . 54
Ventricular Tachycardia . . . . . . . . . . . . . . . . . . . . . . 56
Ventricular Asystole . . . . . . . . . . . . . . . . . . . . . . . . 58
Ventricular Fibrillation . . . . . . . . . . . . . . . . . . . . . . 60
Disturbances of Impulse Conduction
Sinus Arrest or Block . . . . . . . . . . . . . . . . . . . . . . . 64
Sick Sinus Syndrome . . . . . . . . . . . . . . . . . . . . . . . . 66
Atrial Standstill . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Ventricular Pre-Excitation &
Wolff-Parkinson-White Syndrome . . . . . . . . . . . . . 70
Secret to AtrioventricularBlocks . . . . . . . . . . . . . . 73
First-Degree Atrioventricular Block . . . . . . . . . . . . 74
Second-Degree Atrioventricular Block . . . . . . . . . . 76
Third-Degree Atrioventricular Block . . . . . . . . . . . 80
Left Bundle Branch Block . . . . . . . . . . . . . . . . . . . . 82
Right Bundle Branch Block . . . . . . . . . . . . . . . . . . 84
Escape Rhythms
Junctional & Ventricular Escape Rhythms . . . . . . . 88
Miscellaneous Disturbances
Pericardial Effusion (low voltage QRS
complexes & electrical alternans) . . . . . . . . . . . . . . 92
ST Segment & T Wave Changes . . . . . . . . . . . . . . 94
Artifacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Appendix
Anti-Arrhythmic Drugs . . . . . . . . . . . . . . . . . . . . . 100
Recommended Textbook Readings . . . . . . . . . . . . 104
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1
Section
“How To”