Maureen McMichael, DVM, DACVECC, is a Professor in the Department of Veterinary Clinical Medicine and Section Chief of the Small Animal Emergency and Critical Care Section at the University of Illinois College of Veterinary Medicine in Urbana, Illinois, USA.

Ryan Fries, DVM, DACVIM, is an Assistant Professor in the Department of Veterinary Clinical Medicine (cardiologist) at the University of Illinois College of Veterinary Medicine in Urbana, Illinois, USA.

Preface ix

Acknowledgments xi

Introduction xiii

1 Normal ECG 1

Before recording 1

ECG set up 2

Recording the ECG 2

What is measured 3

Normal ECG 3

Calculating the heart rate 3

Calculating the mean electrical axis 5

Measuring the complexes 5

2 Bradyarrhythmias 8

Sinus bradycardia 8

Sinus arrhythmia 9

Sinus arrest 10

Atrial standstill 10

AV block overview 12

First-degree AV block 12

Second-degree AV block 12

Third-degree AV block 13

Asystole 15

Cardiopulmonary arrest 16

Escape rhythms 20

3 Tachyarrhythmias 22

Atrial premature complexes 22

Ventricular premature complexes 23

Differentiating SVT from VT 25

Supraventricular tachycardia 27

Atrial fibrillation 29

Ventricular pre-excitation 32

Re-entrant tachycardia 33

Wolff-Parkinson-White syndrome 34

Ventricular tachycardia 36

Accelerated idioventricular rhythm 39

Ventricular flutter 40

Ventricular fibrillation 40

Torsade de pointes 41

4 Miscellaneous arrhythmias and cardiac conditions 42

Artifacts and anomalies 42

Arrhythmogenic right ventricular cardiomyopathy 42

AV junctional rhythms 45

Junctional escape beats 45

Junctional rhythm 46

Bradycardia-tachycardia syndrome (sick sinus syndrome) 47

Electrical alternans (pericardial effusion) 48

Left bundle branch block 50

Left anterior fascicular block 51

Right bundle branch block 52

ST segment abnormalities 52

T wave abnormalities 53

Canine congestive heart failure-mitral valve insufficiency 55

Canine dilated cardiomyopathy 58

Feline aortic thromboembolism (saddle thrombus) 61

Feline congestive heart failure 64

Heartworm-caval syndrome (CS) 68

Pericardial effusion 73

5 Electrolyte disturbance and the ECG 77

Hyperkalemia 77

Hypokalemia 78

Hypercalcemia 78

Hypocalcemia 79

6 Emergency algorithms 80

Bradycardia algorithm 80

Tachycardia algorithm 80

Asystole algorithm (CPR) 80

Arrhythmia drug chart 80

Further reading 86

Index 87