Rapid Review of ECG Interpretation in Small Animal Practice PDF
Preview Rapid Review of ECG Interpretation in Small Animal Practice
Rapid Review ECG Interpretation In Small Animal Practice prelims.indd 1 10/9/13 10:40 PM TThhiiss ppaaggee iinntteennttiioonnaallllyy lleefftt bbllaannkk Rapid Review ECG Interpretation In Small Animal Practice Mark A. Oyama DVM Professor Department of Clinical Studies Matthew J. Ryan Veterinary Hospital University of Pennsylvania Philadelphia, PA, USA Marc S. Kraus DVM Senior Lecturer College of Veterinary Medicine Cornell University Department of Clinical Sciences Ithaca, NY, USA Anna R. Gelzer Dr. med. vet., PhD Heart & Rhythm Veterinary Specialists Ithaca, NY, USA prelims.indd 3 10/9/13 10:40 PM CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2014 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Version Date: 20131028 International Standard Book Number-13: 978-1-84076-654-7 (eBook - PDF) This book contains information obtained from authentic and highly regarded sources. While all reasonable efforts have been made to publish reliable data and information, neither the author[s] nor the publisher can accept any legal responsibility or liability for any errors or omissions that may be made. The publishers wish to make clear that any views or opinions expressed in this book by individual editors, authors or contributors are personal to them and do not necessarily reflect the views/opinions of the publishers. 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CCC is a not-for-profit organization that pro- vides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com CONTENTS Preface 6 Abbreviations 7 Section 1 Principles of Electrocardiography 9 Section 2 Evaluation of the Electrocardiogram 17 Section 3 Approach to Evaluating Arrhythmias 27 ECG Cases 35 Index 93 prelims.indd 5 10/9/13 10:40 PM PREFACE Clinicians can choose from many different cardiac the subject. Following a brief consideration of the diagnostic tests when assessing dogs and cats theoretical basis of the ECG, a systematic approach with heart disease. Many of these modalities, to interpretation is presented in the introductory such as thoracic radiography, are widely used and chapters. Included are several flow charts that modalities such as echocardiography as well as new will help users to diagnose arrhythmias with more cardiac blood and biomarker tests are increasingly confidence. These sections cover determination of available. Notwithstanding the availability of these heart rate, measurement of intervals, derivation and other tests, the standard electrocardiogram of the mean electrical axis, criteria for atrial (ECG) is an indispensable part of cardiac medicine. and ventricular enlargement or hypertrophy, It can be obtained easily, rapidly, and inexpensively, intraventricular conduction disturbances, and both and with little to no risk to the patient. Results can normal and abnormal cardiac rhythms. The second be interpreted in real time and its format lends itself part of the book contains a comprehensive collection to easy electronic transmission should consultation of real cases and ECG tracings in an easy to use with a remote specialist be desired. The ECG is the format. The cases cover the common arrhythmias gold standard for assessment of cardiac rhythm encountered in small animal medicine, and will disturbances, and a sound working knowledge of help develop the necessary skills to assess the ECG ECG principles is needed for proper interpretation. quickly and accurately in both the dog and the cat. Most veterinarians have some experience in We hope that you find this book useful and that it ECG interpretation, but many still feel uncertain makes interpretation of the ECG an enjoyable and about their ability in this respect. ECG textbooks productive endeavor. are often lengthy, detailed, and not intended for immediate clinical application. This book is Mark A. Oyama designed with the general practitioner in mind, and Marc S. Kraus presented as a concise and practical overview of Anna R. Gelzer 6 prelims.indd 6 10/9/13 10:40 PM ABBREVIATIONS AC alternating current LAFB left anterior fascicular block AF atrial fibrillation LBBB left bundle branch block AFL atrial flutter MEA mean electrical axis AP accessory pathway RBBB right bundle branch block ARVC arrhythmogenic right ventricular SA sinoatrial cardiomyopathy SB sinus bradycardia ATP adenosine triphosphate SSS sick sinus syndrome AV atrioventricular SVA supraventricular arrhythmia AVRT atrioventricular re-entrant tachycardia SVT supraventricular tachycardia cTnI cardiac troponin VF ventricular fibrillation ECG electrocardiography/electrocardiogram VPC ventricular premature contraction FAT focal atrial tachycardia VT ventricular tachycardia ICU Intensive Care Unit 7 prelims.indd 7 10/9/13 10:40 PM 8 prelims.indd 8 10/9/13 10:40 PM Section 1 PRINCIPLES OF ELECTROCARDIOGRAPHY The electrocardiogram (ECG) is a graphical record ECG LEAD TERMINOLOGY of electric potentials generated by the heart muscle In order to record an ECG waveform, a differential during each cardiac cycle. These potentials are recording is made between two electrodes, placed detected on the surface of the body using electrodes on different points on the body. One of the attached to the limbs and chest wall, and are then electrodes is labeled positive, and the other negative. amplified by the electrocardiograph machine and The positions of the electrodes on the body are displayed on special graph paper in voltage and standardized (Fig. 1.1) and defined as RA = right time. The ECG serves to characterize arrhythmias arm, LA = left arm, and LL = left leg. The output and conduction disturbances. from each electrode pair (differential recording) is referred to as a lead and numbered with the Roman INDICATIONS FOR ECG RECORDINGS numerals I, II, and III. These leads are called limb • Evaluating arrhythmias and heart rate leads. disturbances detected on auscultation. • History of syncope (fainting) or episodic weakness. • Cardiac monitoring during anesthesia. • Cardiac monitoring in critically ill patients. • Monitoring changes in rate and rhythm due to drug administration. • Assessing changes in ECG morphology and heart rate due to electrolyte imbalances associated with extracardiac disease or drug toxicities. • In addition, the ECG may also be helpful to identify anatomical changes due to myocardial I hypertrophy or dilation, and detect pericardial disease. However, echocardiography has largely replaced the ECG for these indications due to its RA LA superior sensitivity. I = LA – RA II = LL – RA III = LL – LA II III Fig. 1.1 The standardized positions of the electrodes on the body are defined as RA = right arm, LA = RL LL left arm, and LL = left leg. The output from each electrode pair is referred to as a lead and numbered with the Roman numerals I, II, and III. 9 Oyama layout vfinal.indd 9 10/9/13 9:50 PM
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