The Minnesota Code Manual of Electrocardiographic Findings, 2nd edition

The Minnesota Code Manual of Electrocardiographic Findings: Standards and Procedures for Measurement and Classification

The Minnesota Code Manual of Electrocardiographic Findings including measurement and comparison with the Novacode

Standards and Procedures for ECG Measurement in Epidemiologic and Clinical Trials

Second Edition New and Enlarged

Ronald J. Prineas, MB, BS, PhD Richard S. Crow, MD Zhu-Ming Zhang, MD

Illustrated by Xueling Hu, M.S.

From the EPICARE, Division of Public Health Sciences, Wake Forest University School of Medicine, and The Division of Epidemiology, School of Public Health, University of Minnesota.

Ronald J. Prineas Wake Forest University School of Medicine Winston-Salem, NC USA [email protected]

Richard S. Crow University of Minnesota Minneapolis, MN USA [email protected]

Zhu-Ming Zhang Wake Forest University School of Medicine Winston-Salem, NC USA [email protected]

ISBN 978-1-84882-777-6 e-ISBN 978-1-84882-778-3 DOI 10.1007/978-1-84882-778-3 Springer London Dordrecht Heidelberg New York Library of Congress Control Number: 2009937250 © Springer-Verlag London Limited 2010 Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency. Enquiries concerning reproduction outside those terms should be sent to the publishers. The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant laws and regulations and therefore free for general use. Product liability: The publisher can give no guarantee for information about drug dosage and application thereof contained in this book. In every individual case the respective user must check its accuracy by consulting other pharmaceutical literature. Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com)

Dedication: To our mentors and colleagues, Henry Blackburn, Pentti Rautaharju, and in memory of Geoffrey Rose

Contents Preface for the second edition ............................................................................................................. ix Preface for the first edition .................................................................................................................. xi Acknowledgments ............................................................................................................................... xiii 1

What is the Electrocardiogram or ECG? ............................................................................................. The Electricity Part of the ECG

1

2

ECG Leads .......................................................................................................................................... Bipolar Limb Leads(I, II, III) / Unipolar Limb Leads(aVR, aVL, aVF) / Chest Leads (V1, V2, V3, V4, V5, V6)

6

3

Measuring Devices .............................................................................................................................. 10 Recording Paper Grid / Measuring Loupe / Plastic Ruler / Calibration Deflection / Beats to Be Measured / Mathematical Symbols

4

Q-QS Waves (1-Codes) ....................................................................................................................... 16

5

Frontal Plane QRS Axis (2-Codes) ..................................................................................................... 49

6

High R-Waves (3-Codes) .................................................................................................................... 55

7

ST Segment Depression (4-Codes) and Negative T-Waves (5-Codes) ............................................... 60

8

Atrioventricular (A-V) Conduction Defects (6-Codes) ....................................................................... 98

9

Intraventricular Conduction Defects (7-Codes) .................................................................................... 111

10 Arrhythmias, 8-Codes.............................................................................................................................134 11 Miscellaneous Codes (9-Codes) .......................................................................................................... 159 12 Exact Measurements ............................................................................................................................. 187 Frontal Plane QRS Axis / Amplitude Measurements / Q-X, Q-T Intervals 13 Coding the Whole ECG ....................................................................................................................... 203 Coding Hierarchy / Data Recording 14 ECG Data Acquisition Procedures and Maintenance of Recording Quality including Technician Training ............................................................................................................................................... 206 Twelve-Lead Rest ECG Using Single Channel Recorder / Twelve-Lead ECG Using Multichannel Recorder / Minimizing Biologic Variability 15 Criteria for Significant Electrocardiographic Change ......................................................................... 226 16 ECG Indices That Add to Independent Prognostication for Cardiovascular Disease Outcomes ........ 263 17 Quality Control of Visual and Electronic Coding ............................................................................... 270 Appendix A Minnesota Code 2009 ....................................................................................................... 277 Q and QS Patterns / QRS Axis Deviation / High Amplitude R-Waves / ST Junction (J) and Segment Depression / T-Wave Items / A-V Conduction Defect / Ventricular Conduction Defect / Arrhythmias / ST Segment Elevation / Miscellaneous Items / Incompatible Codes Appendix B Novacode and Minnesota Code Equivalents ................................................................... 287 Appendix C ..........................................................................................................................................325 Major and Minor ECG Abnormalities for Population Comparisons with Minnesota Code and Novacode Equivalents Index ..................................................................................................................................................... 327 vii

Preface to the Second Edition The manual is suitable for training electrocardiographers and technicians and can be accompanied by sets of training ECGs already coded by trainers. It is our expectation that the manual will serve as a reference, guide, and training source for those conducting studies that require objective evidence of cardiac disease, both prevalent and incident, by noninvasive, highly standardized, inexpensive recording of the electrocardiogram. In our own ECG Reading Center, this has included epidemiologic studies among healthy populations, diabetics, psychiatric patients, pregnant women, cohorts of patients with clinical heart disease, populations exposed to environmental contaminants such as arsenic, populations exposed to Chagas disease, and in clinical trials of HIV-infected participants, diabetics, hypertensives, children, the aged, dietary intervention studies and phase I and phase II drug studies. It is 28 years since the publication of the first edition, which is now out of print. We have produced a second edition because, in the interim, we have received continuous requests over the years for copies of the book that no longer existed and also because there have been refinements and extensions to the Minnesota Code that allow a greater range of abnormalities to be coded; there are even clearer means of demonstrating correct and standardized methods of measurements that are incorporated into this second edition; some minor coding rules have been changed; and now the use of the code has been greatly expanded and is used in countless epidemiologic studies and clinical trials worldwide. Even as far back as 1981 the initial publication describing the Minnesota Code was chosen as a citation classic (CC/NUMBER 51 of SCI December 21, 1981:This Week’s Citation Classic :Blackburn H, Keys A, Simonson E, Rautaharju P & Punsar S. The electrocardiogram in population studies: a classification system. Circulation. 21:1160-75; 1960). It had been cited more than 405 times in published articles. Since then the bibliography has grown many times larger–at the time of writing, over 700 citations were listed in Pub Med. The introduction of digital ECG recordings and analysis has only expanded the role of the Minnesota Code now encompassed in computer programs to analyze digital signals transferred over phone lines or directly on solid digital recording platforms such as CDs. The latter notwithstanding, archival paper tracings are continually mined for data that were collected

without digital recording and that are accompanied by other uniquely rich data. Despite my expectations during the 1960s that such archives would cease to be used after the introduction of digital recording, the tide of such treasures has hardly ebbed. The changes included in this edition arise from more than a quarter of a century of directing central ECG reading and research centers and collectively 60+ large and small epidemiologic studies and multicenter national and international clinical trials. The changes include the description of a new measuring loupe in Chap. 3, developed over the past decade, to better serve a more efficient and a more extensive span for measurement of relevant durations, voltages, and deviations from the isoelectric line. In Chap. 4, the old code 1-2-6 has been removed because of lack of prognostic value, and for a similar reason, code 1-2-8 has been down-coded to 1-3-8 to better represent its place in the hierarchy of Q-wave abnormalities. In addition, a new code 1-3-7 has been added to extend coding of inferior myocardial infarction. In Chap. 7, newer more precise methods of measuring ST-segment and T-wave voltages are presented. Additions to conduction defects in Chap. 9 include measurements for and classification of the Brugada syndrome ECG pattern (code 7-9) and fragmented QRS (code 7-10) – both of the latter codes have been associated with sudden death. The chapter on arrhythmias has minor modifications from the first edition, but, notably, premature beats need no longer be “frequent ” by the old definition to be coded in a standard 12 lead ECG, where the presence of any premature beats is significant for prediction of future cardiovascular disease. In Chap. 11, additional codes have been added for lead reversal (with many examples), technical quality, left atrial enlargement (code 9-6), and early repolarization (code 9-7). More detailed criteria are presented in Chap. 12 for the measurement of QT interval, so important in testing all new drugs. New coding forms are presented in Chap. 13, and Chap. 14 on ECG data acquisition has been re-written and expanded to include training of ECG recording technicians and maintenance of recording quality. Chap. 15 on the criteria for significant serial change has been developed in a much more comprehensive manner and has added descriptive tables and new codes for documenting serial change myocardial infarction. Chap. 16 is a new addition on continuous measurements, which can be derived from a standard 12-lead ECG that have independent prognostic value ix

and includes description of ultrashort heart rate variability. Chap. 17 on quality control is now greatly expanded and includes quality control directions and documentation for both paper (visual) and electronic ECGs. Appendix A has all of the new Minnesota Codes incorporated. Appendix B is new and details

the criteria and classification of the Novacode, including significant serial change, MI diagnosis, and comparisons with the Minnesota Code. Finally, Appendix C lists a summary of minor and major code abnormalities that can be used in comparisons of subgroups in experimental studies and analyses.

NC, USA

Ronald J. Prineas May 2009

x

Preface to the First Edition The electrocardiogram (ECG) is mainly used in clinical and hospital practice for diagnosis and for prognosis. But it is also used for systematic population studies and clinical trials in and outside hospital, where a repeatable, valid, and quantitative method is required for classification of ECG findings related to disease. Useful classification depends, in turn, on standardized methods of acquiring the data, on mounting (sampling), and on reading and measurement of the ECG. In systematic studies the ECG is read centrally, unbiased by clinical information. This blinded classification provides objective criteria for individual events, group differences, and for sequential changes in individuals and groups. Measurement classification criteria and procedural rules for standardized ECG coding were devised and published from this laboratory and became known as the Minnesota Code (Blackburn H, Keys A, Simonson E, Rautaharju P, Punsar S. Circulation. 1960;21:1160). Current updated criteria and coding rules are found in the Appendix to this manual. Since 1960, these criteria and coding rules have been tested and occasionally slightly modified to improve validity and repeatability. The rules are nevertheless continually subject to variation in application because of different quality of recording, baseline trace width, characteristics of the tracing, and the number of beats to be measured. A set of definitions and procedural rules has evolved in this and other laboratories to define more precisely wave onset and offset and wave segments. Other factors affecting standardized ECG coding include ECG coder training, data acquisition, patient preparation, technician training, and quality control. These are presented in this manual along with unambiguous definitions and measurement procedures. The current Minnesota Code criteria are found in the Appendix, in sequence from 1–9-codes. In the body of the manual, separate chapters are provided on the exact measurement of continuous ECG variables such as frontal plane axis and heart rate, on standard ECG acquisition and mounting, and on quality control of coding, as well as detailed presentation of the wave classification system. The codes in the Appendix do not need to be learned by rote for this manual to be used as a training and testing tool. Early in training as ECG findings are recognized, the detailed code may be referred to. It is, however, necessary to develop an

efficient personal system for scanning each ECG for all codable findings, and to learn thoroughly how to measure the findings detected. While the contents of the coding chapters of this manual need not be mastered in one course, the manual should be used as reference when there is doubt how to measure a particular wave form. The ECG measurements described here are easily applied by intelligent, trained, and dedicated medical, technical, or lay persons. The manual can be used by electrocardiographers or experienced investigators to teach measurement and coding of the ECG. This laboratory has for two decades trained “ordinary” university students in coding skills as part-time workers for periods of 1–3 years. Nurses, physicians, and technicians have also been successfully trained. Adherence to specific rules and ongoing quality control allow comparisons of results from different observers and centers at different times. Training requires intensive instruction for a full 10 day course, followed by continual experience. An introductory lecture on electrocardiographic history and physiology imparts understanding of the reasons for the measurements and codes, and is tailored to the sophistication of the students. It explains the current setting of ECG coding for population comparisons and clinical trials and their different requirements from clinical diagnosis. Within 3 months of initial training, further testing for accuracy and speed is carried out. The introductory lectures also explain the recording of 12 lead ECGs and the expected patterns for each lead, and identify P-, Q-, R-, S- and T-waves. Coders are taken sequentially through the coding material in each of Chapters 3 through 12. At the conclusion of each chapter, sample electrocardiograms are coded for the findings and measurements described in that chapter. The student codings are checked by the instructor before proceeding to the next chapter and remedial work is assigned where needed. Specific codes are sought in each lead separately to recognize the range of normal patterns in each lead. At the conclusion of instruction with the text material and practice ECGs, a separate test packet of approximately 20 ECGs, as described in Chap. 13, and enriched with examples of major codable findings, is coded for the complete ECG. Results are checked by the instructor. Duplicate coding of actual “unknown” ECGs then starts, initially, with a new coder against a senior experienced coder for xi

the first three to six months of the program. In this period, misunderstanding of the coding rules is discovered and corrected. After approximately three months of on-the-job coding, new test packets with approximately 50 ECGs per packet are coded and tabulated according to standard tables of repeatability (Rose G, Blackburn H, Gillum RF, Prineas RJ. Cardiovascular Survey Methods.

Geneva: WHO; 1982). Coding rates (speed) and test results (accuracy) are compared among coders so that the suitability of coders, or the need for retraining, is determined. Test packets are available from the Director, ECG Coding Laboratory, Laboratory of Physiological Hygiene, School of Public Health, Stadium Gate 27, 611 Beacon Street SE, University of Minnesota, MN 55455, USA.

Was written in Minnesota

Ronald J. Prineas MB, BS, PhD January 1982

xii

Acknowledgements We thank many programmers, coders, and electrocardiographers, who over the past decades, have contributed much to the process of ECG coding and refinement of rules of application, and in particular, we acknowledge the contributions of Dr. Yabing Li and Charles Campbell for unflagging dedication to their demand for precise definition of code items for both visual and electronic ECG records. We also thank Dr. Elsayed Soliman for his specific refinements in early repolarization definitions.

xiii

1 What Is the Electrocardiogram or ECG1? Electrocardiogram is a written record of a heart beat, while electrocardiograph is an instrument with which it is recorded. The same is true for telegram, written record, and telegraph, the instrument. The abbreviation EKG is obsolete in this country. It comes from the German word, Das Elektrokardiogramm as many early works are done in Germanic countries. The spelling and abbreviation has been anglicized to ECG. An Italian, Galvani, introduced in 1791 the concept that all living tissue can produce an electric current when adequately stimulated. He also showed that injured muscle generates current. If a living nerve attached to a healthy frog leg muscle were allowed to touch the injured area of another frog’s muscle, the healthy nerve–muscle frog preparation would twitch! The Germans, Kolliker and Muller, showed, over a hundred years ago, with the same type of nerve–muscle preparation, that an electrical current was produced rhythmically with each contraction of an animal heart. An Englishman, Waller, in 1887 was the first to demonstrate in his pet bulldog Jimmie that the electrical action of the heart could be registered from the surface of the body. He is also credited with making the first human ECG, which he called a cardiogram. This was registered by light reflected from a capillary tube of mercury, which oscillated with each heart beat from the electrical potential differences the heartbeat causes between the right and left hand. Einthoven, a Dutchman, worked for some years at Leiden with ECG recording instruments and finally in 1901 devised his own instrument a string galvanometer, so sensitive to changes in intensity of electric currents and so rugged and stable in operation that a new branch of medicine, electrocardiography, was made possible. His instrument consisted of a stretched string of quartz filament coated with silver and suspended in a strong magnetic field. The secret of his success was this high-resistance tiny quartz string, which he first made by attaching fused quartz to the tail of an arrow, heating the quartz to a critical point and firing the arrow, thus producing a very fine, uniform string. The history of electrocardiography thereafter is too detailed to recount, but Einthoven’s instrument brought it all about. It was early imported in Britain and the United States and widely used here until after the Second World War. The tiny heart currents are now picked up and amplified with transistorized amplifiers, and instead of photographs of a vibrating string we have an “instant ECG,” from a direct writing stylus on a moving paper strip. In addition, we now transmit the ECG by FM radio, or by telephone. We can also record and store the ECG on digital recording media, and can now make ECG measurements and even Minnesota Code classifications with computers by converting the analog wave form to digital, or numerical form. (see www.ecglibrary.com/ecghist.html.) 1

The development of the ECG wave generation and propagation is not meant to be comprehensive but as a guide to expected wave patterns for coding. More comprehensive descriptions can be found in text books of clinical ECG interpretation.

1

The Electricity Part of the ECG Heart is made up of many interwoven and interconnected bundles of muscle. Each individual muscle cell has an electrical charge as we learned from Galvani and others. With each heart beat, a wave of electrical excitement moves rapidly through the thousands of linked heart muscle cells. There is at that moment an imbalance of the electrical charge at the outer membrane of these cells caused by a rapid flux of charged ions through the cell membrane. As the wave of excitation passes through the heart muscle, millions of individual cell charge set up an electrical current in the chest. This current flows to the surface, and at the skin produces differences in electrical voltage, which can be measured between pairs of electrodes placed at any two points on the body. At the beginning of each heart beat, excitation starts from the firing of the pacemaker sinus node in the right atrium and passes in as wave through both atria, the upper thin-walled chambers of the heart. The tiny differences in voltage between distant points on the skin allow us to register a small deflection on a meter, a galvanometer, named after Galvani. Because the paper is moving at the time the meter needle deflects, a little rounded wave is produced. Einthoven named it the P-wave. This is followed by a delay as the impulse is received at the upper part of the ventricular septum, in the A-V node, and this lag is recorded on paper as a straight line. The exciting electrical wave then spreads rapidly through the large muscle walls of the ventricles over the special (His) bundle of conducting fibers. The ventricular excitation causes sharp and large deflections (still only 1-4 mv), and these deflections as registered on the moving paper are called the QRS waves in the ECG.

Summary

Fig. 1-1 SA NODE

R LEFT ATRIUM T

RIGHT ATRIUM A-V NODE

RIGHT VENTRICLE

P LEFT VENTRICLE

Q

S

LEFT BUNDLE

RIGHT BUNDLE

FIGURE 1.1. Normal heart beat is initiated by spontaneous firing of the sinus (SA) node in the right upper chamber of the heart (right atrium) 2

As the excitation wave goes through the ventricles, the activated cardiac muscle contracts (excitation–contraction coupling) and ejects the blood into the systemic and pulmonary circulation. Then the electrical charges at the muscle cell return in a slowly receding wave to the original resting, electrical state. This slower wave of electrical recovery of the ventricular muscles is inscribed on the moving paper as another rounded wave called the T-wave. The shape and direction of the QRS and T-waves depend on the sequence of depolarization and repolarization, the balance and direction of the individual electrical forces of the wave of excitement through the heart, and the location of the electrodes on the skin. For illustration, consider two poles in water with a pressure gauge on each. One hooks up the

R

Fig. 1-2

T P

S

Q

FIGURE 1.2. The excitation wave passes through the muscles of both atria, activating them to contract. This activation produces electrical currents in the chest, which are measured as differences of potential between the electrodes on the body surface. A moving paper strip records these as the small rounded P-wave of the normal sinus beat R

Fig. 1-3

T P P-R

Q

S

FIGURE 1.3. The electrical wave of activation reaches the atrioventricular (A-V) node between the atria and ventricles and there is a brief delay. The P-R interval includes the P-wave and the period of delay in the A-V node 3

two pressure gauges so that the meter reads positive if the right–hand pole registers a higher pressure than does the left. Scooping up a wave in the middle and shoving it toward this right-hand pole makes the pressure higher there and the meter registers an upward deflection. A wave toward the left pole makes the pressure lower at the right–hand pole and the meter, and therefore, registers a downward deflection. If a wave starts in the middle and its force travels equally toward and reaches each pole at the same time, we get no difference in pressure, and hence no deflection at all.

R

Fig. 1-4

T P

S

Q

FIGURE 1.4. The activation rapidly descends the bundle of His in the muscular septum between the two ventricles, and activates those muscles from left to right. This septal activation produces the first ventricular deflection of the ECG, the Q-wave

R

Fig. 1-5

T P

Q

S

FIGURE 1.5. The activation then spreads rapidly through the special conducting tissues of the ventricles and the wave progresses, in a generally right to left direction, producing the major ventricular deflection, the R-wave. All regions of the ventricles are eventually activated, the entire QRS complex is recorded, and the ventricles contract and pump blood 4

R

Fig. 1-6

T P

S

Q

ST SEGMENT

FIGURE 1.6. There follows a short period of relative inactivity recorded as the ST segment

R

Fig. 1-7

T P Q

S

R

Fig. 1-8

T P

Q

S

FIGURES 1.7 and 1.8. Then the recovery wave spreads in reverse of depolarization (from the epicardium through the ventricular wall) over the same pathway “repolarizing” the heart, producing a broad blunt wave, the T-wave that is in the same direction as the R wave 5

2 ECG Leads The body acts as a large conductor of electrical currents generated by heart. To record, these currents require that only any two points on the body be connected to the electrocardiograph. This establishes the necessary completion of an electrical circuit and is done by means of electrodes attached to the limbs or the chest, each pair of attachments being one “lead.” The ECG leads generally used are I, II, III, aVR, aVL, aVF, V1, V2, V3, V4, V5, and V6.

Bipolar Limb Leads (I, II, III) The major direction of the electrical force wave through the heart ventricles goes from the right to left in a downward direction. Consequently, if we attach the ECG electrodes on the arms with the positive pole of the galvanometer as the left arm, then as the excitation wave approaches it, there is a positive or upright reflection. Actually, the forces from instant to instant form a loop in space, initially and briefly toward the right arm, giving the small Q, then sweeping in a broad orbit toward the left arm, giving the R, and back to the center giving the small S.

FIGURE 2.1. 6

The right arm/left arm lead is lead I and is usually registered as a predominantly upward wave because the average and major direction of the wave force is toward the positive left arm (see Fig. 2.1). The voltage difference between the right arm and the left leg electrodes is measured by lead II. The major direction of the electrical force wave goes parallel, or almost so, to this lead, from above downward, and so the ECG again registers upright, as a mainly positive wave. In lead III, potential differences are reflected between the left hand and left leg. Here the average major force of the wave rolls over the line of the lead at right angles, and we get a low, absent, or approximately equal positive–negative wave (see Fig. 2.1). Einthoven devised this triangle (Fig. 2.2) (right arm, left arm, left leg) and calculated that if we record these three leads at exactly the same time, the height of waves in I and III always adds up to those in lead II. He taught us how to calculate the direction of the major wave force from the voltage values in any two... of these... leads. This is called measuring the electrical axis, which we take up in Chap. 5. The predominant deflection of the QRS waves usually points upward, is positive in I and II, and may be up, down, or in-between in III.

Fig. 2-2

FIGURE 2.2.

Unipolar Limb Leads (aVR, aVL, aVF) The potential differences in the right arm, left arm and left leg are also recorded between an electrode from each of these sites and a neutral or zero potential by connections from all limb electrodes within the electrocardiograph. The unipolar leads then reflect potential values from the right arm (aVR), left arm (aVL), and left leg (aVF) and are useful in determining the electrical position of the heart. The ECG waves in aVR are generally negative or downward deflections; those in aVL and aVF may be upright or of intermediate position depending on the anatomic and electrical position of the heart (see Fig. 2.3). 7

FIGURE 2.3.

Chest Leads (V1, V2, V3, V4, V5, V6) We owe to Drs. Wilson and Johnston from the University of Michigan at Ann Arbor the development of chest leads. Much of our information about heart attacks and other heart muscle problems is obtained from these six leads that have been widely used for the last 60+ years. They are often called Wilson leads or V leads or precordial leads, and are named V1, V2, V3, V4, V5, V6. Six is standard but more may be taken. The chest leads are also unipolar leads, reflecting potential differences between six points on the chest and a combined potentials lead inside the electrocardiograph from the three extremity electrodes. For reference purposes we will define these positions here, but it requires practice to locate the landmarks on a real chest: Subscript 1 (V1) shall be used for a lead from the right sternal margin at the fourth intercostal space; subscript 2 (V2) for a lead from the left sternal margin at the fourth intercostal space; subscript 3 (V3) for a lead midway between 2 (V2) and 4 (V4); subscript 4 (V4) for a lead from the fifth intercostal space where it is crossed by the midclavicular line; subscript 5 (V5) for a lead from the junction of the left anterior axillary, line with the horizontal position of position 4; subscript 6 (V6) for a lead on the same horizontal level but at the left midaxillary line (see also Chap. 14). As we look at the body and the heart from the front, or in the frontal plane, we find that the major wave force is directed from body’s right to left and down, which accounts for the direction of deflection in frontal plane limb leads I, II, and III. For the chest leads, we look at the heart and body from above, i.e., at the horizontally oriented plane. We find that the major QRS force is directed to the left and somewhat toward the back. 8

Each of these chest electrodes register positive when the major wave force sweeps toward it. The main wave force is largely away from the positive electrode at V1 and V2, and so those leads will register predominantly downward deflections. It is toward V5 and V6 so they will register predominantly upward deflections, while V3 and V4 will be somewhere in-between or equiphasic. In detail, the loop starts out toward V1 and away from V6, registering a small R in V1 and Q in V6. The broad mass of the loop then creates the main force described above, away from V1 and V2, toward V5 and V6 (see Fig. 2.4).

FIGURE 2.4.

This is the pattern that should be remembered now, usually negative QRS waves in V1 and V2 and positive waves in V5 and V6 with a transitional zone in between. One should be alerted if the wave directions are different from this pattern. The T-wave recovery force also moves in a slower and smaller loop in space and generally follows the orientation of the QRS forces. With some small exceptions that will be learned, the direction of the T-wave in the limb and chest leads is in the same direction as that of the predominant QRS wave. One should quickly detect whether the T-wave is opposite in direction to the main direction of the QRS wave. 9

3 Measuring Devices The amplitude (distance of positive peaks and negative nadirs from the baseline) and duration (width from beginning or onset to end or offset) of ECG waves are measured by visual reference to the grid lines on the ECG recording paper, or by use of devices including a magnified measuring loupe or a clear plastic ruler on calipers. Use of such devices has been demonstrated to improve coding repeatability. Recording Paper Grid ECG recording paper is divided into a grid of heavier lines 5 mm apart and lighter lines 1 mm apart. When, as in the majority, ECGs are recorded at a paper speed of 25 mm/second, this means that each millimeter mark on the horizontal axis of the grid represents 1/25 second (0.04 second), 0.25 mm represents 0.04/4 = 0.01 second; 0.5mm = 0.04/2 = 0.02 second; and 0.75 mm = 3 × 0.04/4 = 0.03 second (see Fig. 3.1). Amplitude of waves and points of wave onset and offset are measured in millimeter deviations from the baseline (see Fig. 3.2). For durations, (onset to offset 1 × mm = 40 ms, and for amplitude 1 × mm = 100 µV = 0.1 mV.

1mm. 5mm.

a = 0.25 mm.= 0.01 sec. = 10 ms b = 0.5 mm.= 0.02 sec. = 20 ms c = 1 mm.= 0.04 sec. = 40 ms

a b c

Fig. 3-1

FIGURE 3.1. 10

Measuring Loupe For small waves and for wave duration obscured by a grid line, a magnified measuring device must be used. The loupe used in this ECG reading center has improved the repeatability of measurements between different coders and on different occasions. This anastigmatic Loupe 10 × has high resolving power and wide visual field, with a grid protected by a coverplate on the bottom (see Fig. 3.4). It has three precision-constructed achromatic lenses (to enable observers to simultaneously inspect the whole picture area, i.e., flat objects less than 32 mm in diameter) and with specially designed scaled reticle for ECG measurement. It is placed flat on the tracing in a good light, positioned in front of the coder. The top lens system may be focused by a screw. With 20 mm effective aperture of the loupe, an observer can inspect the whole image field by merely moving his/her eyeball, without moving his/her face. This is an advantageous feature for a QT interval measurement. The loupe with special reticle may be obtained from our ECG Reading Center, at cost, by writing to the Director, Epidemiological Cardiology Research Center (EPICARE), Department of Epidemiology and Prevention, Division of Public Health Sciences, Wake Forest University School of Medicine, 2000 West First Street Suite 505, WinstonSalem, NC 27104, USA.

FIGURE 3.4.

Fig. 3-4

SC

LUPE

ALE

3 Lenses

10 8 6

0

10 9 8 7 6 5 4 3 2 0

1

2

3

4

5 6

8

7

9

10 11 12 13 14 15 16MM

1 2

SEC 25MM SEC 50MM MM

3 .12 0.04 0.02 0.04 3 1 2

.22 5

4 5

.44 .22 11

6 7 8 9 10

12

1

2

3

4

5

Plastic Ruler For measuring longer wave durations and intervals and higher waves, a clear flexible plastic ruler with 1 mm interval is useful. A transparent ruler enables the coder to see the ECG trace beneath so that it can be positioned most accurately. The thinner the ruler, the less will be parallax error.

Calibration Deflection The first deflection usually seen in the ECG is a square calibration wave (see Fig. 3.5). This should be exactly 10 mm high from the top margin of the baseline to the top of the square wave.

Fig. 3-5

calibration wave

FIGURE 3.5.

Beats to Be Measured The first beat in a lead is defined as a beat with a complete P-wave, QRS complex, and T-wave. If part of the P-wave is missing, that beat is not included for coding measurements (see Fig. 3.6). The last beat in a lead to be included for coding measurement must include the T-wave, at least to its peak (see Fig. 3.7). 13

1st complete codable beat

Fig. 3-6

1st complete codable beat

FIGURE 3.6.

Fig. 3-7 last complete codable beat

last complete codable beat

FIGURE 3.7. 14

Mathematical Symbols To conserve space and to make precise definitions, mathematical symbols have been used throughout this text for the following: > = greater than < = less than ≥ = equal to or greater than ≤ = equal to or less than So that, 0.06 second < Q duration < 0.07 s, means a Q-wave duration greater than 0.06 second but less than 0.07 second.

Differences in Measurement between Visual and Electronic Measurements There are times when checks (over-reading) need to be made for visual confirmation of computer coding of digital ECG data. At such times, it is important to recognize that there are differences in measurement precision between the two modes of coding. First, most electronic programs use either an average or median beat, whereas visual coding generally requires accepting the findings in the majority of beats. Second, the electronic measurement starts from an isolelectric line of virtually no width, whereas the paper record has to contend with an isolelectric line (baseline) of finite width. The electronic signals at the time of publication can measure at a sampling rate of 500 second, so that the electronic measurements applied in computer coding are often a shade longer in duration when measuring specific intervals and a shade greater in measuring voltage deviations from the isoelectric line.1

Reference 1. Rautaharju PM, Seale D, Prineas RJ, Wolf H, Crow R, Warren J. Changing electrocardiographic recording technology and diagnostic accuracy of myocardial infarction criteria: improved standards for evaluation of ECG measurement precision. J Electrocardiography. 1978;11(4):322-330.

15

4 Q-QS Waves (1-Codes) Injured regions of the heart may become electrically inactive. Myocardial infarction is the most frequent cause of this. The normal excitation wave may be altered by this nonfunctioning part of the heart, thus changing the appearance of the QRS complex. In this situation, the early part of the QRS complex appears as a deep, wide negative Q- or QS-wave in certain leads. Smaller areas of injury cause lesser Q-waves. Ideally, one would measure the amplitude and duration of all Q-waves and refer to standard values for classification. Practically, this is too tedious for visual-manual coding. Instead, the code provides classes that generally reflect degrees of Q-QS abnormality according to lead. R

Fig. 4-1

T P

Q R

Fig. 4-2

T P

S

FIGURES 4.1 and 4.2. The 1-codes classify Q- and QS-waves, which also depend on the type of R-wave present. The earliest positive deflection in a QRS complex is the R-wave. Any negative deflection that precedes the R-wave is a Q-wave (see Fig. 4.1). Any negative deflection that follows the R-wave is an S-wave (see Fig. 4.2) 16

FIGURE 4.3. A Q-wave and an S-wave may be present in the same complex

FIGURE 4.4. There may be no Q- or S-wave, in which case the QRS complex would consist only of an R-wave 17

FIGURE 4.5. If there is no R-wave, then by definition there can be no Q-wave (because a Q is the first negative wave to precede an R-wave and an S the first to follow). The whole QRS complex is negative and is called a QS-wave

FIGURE 4.6. A special form of the QS-wave is a W pattern. Here the negative QRS complex is notched with a central deflection. However, the peak fails to reach the reference baseline (the upper margin of the baseline at the onset of QRS) and the W pattern is classified as a QS-wave 18

Fig. 4-7

Q wave amplitude

measure vertically from the onset of the QRS at the lower margin of the baseline to nadir

Fig. 4-8

QS wave amplitude

measure vertically from the onset of the QRS at the lower margin of the baseline to nadir

FIGURES 4.7 and 4.8. The presence or absence of codable Q- or QS-waves depends on the amplitude of the Q- or QS-wave, which must be ≥1 mm in the majority of beats in any lead (with two exceptions for codes 7-7 and 7-8, see Chap. 9), the duration of the Q-wave, which must be ≥0.02 second in the majority of beats in any lead, the amplitude of the accompanying R-wave, and the lead location of the Q- or QS-wave 19

Fig. 4-9

no codable Q

codable QS

FIGURE 4.9. If the amplitude of the Q- or QS-wave is 50% (a majority) of beats. It is not necessary to measure the duration of QS-waves for coding 23

Fig. 4-16

measure vertically from the onset of the QRS to the peak of the R

Fig. 4-17

measure vertically from the onset of the QRS to the peak of the R

R

T

P

S Q

FIGURES 4.16 and 4.17. R-wave amplitude determines the presence or absence of Q- or QS-waves. R-wave amplitude is measured from the upper margin of the P-R baseline at the onset of the QRS complex vertically to the peak of the R-wave (see Fig. 4.16), even if the R-wave is preceded by a Q-wave (see Fig. 4.17) 24

Fig. 4-18 initial R T

R P

S

FIGURE 4.18. R-wave amplitude determines if a Q- or QS-wave is present. If there is no negative wave of ≥1 mm amplitude preceding the R-wave, then the R-wave is called an initial R-wave Fig. 4-19

initial R

P

T

R

S

Fig. 4-20 no initial R

T P

QS

FIGURES 4.19 and 4.20. An initial R-wave must be ≥0.25 mm in amplitude to be classified 25

Fig. 4-21 QS • initial R0.02 sec.

Fig. 4-25

R

R

FIGURES 4.23–4.25. A QS pattern is considered to be present when the R-waves present are 0.02 second (0.5 mm) (see Fig. 4.25). If the initial R is > 0.5 mm, then there is no restriction on the R peak time 27

FIGURE 4.26. An initial R-wave is an exception to the majority rule. If an initial r is present in any beat in a lead, no q- or qs-code is made for that lead except in V1. That is, in V1, an initial R must be present in the majority of beats to be classified an RS pattern. In any other lead, no 1-code is made if there is a single beat having an initial R-wave, even if the majority of beats have Q- or QS-waves

28

Fig. 4-27 code as QS

terminal R>1mm.

R 26 mm.

FIGURES 6.1–6.3. Code 3-1 is coded if any of the following criteria are present: R amplitude >26 mm in either lead V5 or V6 (see Fig. 6.1); R amplitude >20 mm in any of leads I, II, III, or aVF (see Fig. 6.2); R amplitude >12 mm in lead aVL (see Fig. 6.3)

55

Fig. 6-2 3-1 • lead I, II, or aVF • R amplitude > 20 mm.

Fig. 6-3

3-1 • lead aVL • R amplitude > 12 mm.

56

FIGURES 6.4–6.6. Code 3-2 requires that all three conditions be met. First, V1 must have an RS or QRS pattern. The R-wave amplitude in V1 must be ≥5 mm in the majority of beats (see Fig. 6.4). In addition, the amplitude of the R-waves must be equal to or greater than the amplitude of the S-waves, in the majority of beats in lead V1 (see Fig. 6.5). Finally, Second amplitude must be greater than R amplitude in the majority of beats in any one of leads V2–V6 (see Fig. 6.6). All three of these conditions must exist to code 3-2 57

Fig. 6-7 3-3 • lead I • 15 mm.15 mm but ≤20 mm in lead I (see Fig. 6.7); R-wave amplitude in V5 or V6 plus Second or QS amplitude in V1 >35 mm (see Figs. 6.8 and 6.9). Code 3-3 also requires that there is no 3-1 code 58

Fig. 6-9

3-3 V1 QS=13 mm.

V6

R=24 mm.

Fig. 6-10 3-4

aVL

V1

R amplitude >12 mm.

V3

R amplitude >5 mm. R>S amplitude

R<S amplitude

FIGURE 6.10. Code 3-4 is coded if criteria for both codes 3-1 and 3-2 are met

59

7 ST Segment Depression (4-Codes) and Negative T-Waves (5-Codes) Toward the end of ventricular excitation (QRS), the earliest part of the heart to be excited begins to recover or recharge to produce the T-wave. If the heart muscle is injured or short of oxygen, the electrical recovery starts prematurely, and this may produce a sizable current. The trace between QRS and T is then displaced up or down, depending on the location of the injury and on the lead. The ST segment is continuous with the T-wave and both are often coded together; thus, they are learned together. Moreover, certain damage or inadequate blood supply to the heart ventricles may reverse the usual sequence of recovery. This may result in distinctly negative T-waves in leads where they are usually positive. The lead orientation may display, however, low or diphasic (partly positive, partly negative) T-waves and these, along with ST depression, may be indistinct and cause coding problems. ST segment depression coding requires: 1. Identification of the J-point, the junction between QRS and ST 2. Determination of the slope and shape of the ST segment 3. Measurement of the amplitude of ST segment depression Fig. 7-1

R R

P

J Point

T

P

J Point

T

S

FIGURE 7.1 and 7.2. The end of QRS is called J-point, a break in direction of the tracing at the end of QRS. In the accompanying figures, the J-point is marked with an arrow. Correct placement of the J-point is the first requirement for determining ST segment depression and slope 60

Fig. 7-2

R

R

J Point

P

J Point

P

T

T

Q

Fig. 7-3

R

R

P

P

J Point

J Point T

T

FIGURE 7.3. Notice that the J-point is not always level with the preceding P-R baseline and here is below it

61

R

Fig. 7-4

R

J Point

J Point

P

T

T

P

S

FIGURE 7.4. It shows one example of a depressed J-point and another with J-point level with the P-R baseline Fig. 7-5

J

J

FIGURE 7.5. Sometimes the J-point is not such a sharp angle at the end of the QRS. Though a break in the curve between the QRS and ST segment can be seen, the exact point is indeterminate. In such cases, a tangent is drawn along the straightest section to be found (one at least 2 mm in length) of the lower margin of the ST segment at the beginning of ST. The J-point is on the upper margin opposite the point the tangent and the ECG separate

Fig. 7-6

R

R

perfect curves • no J points

P

P

FIGURE 7.6. Where the J-Point is not easily located or where there is no straight part of the ST segment at least 2 mm long for constructing a tangent, a truly curved ST segment exists and no J-point is measured 62

R

Fig. 7-7

two possible J points P

Q

Fig. 7-8

two possible J points

Fig. 7-9

end of QRS

FIGURES 7.7–7.9. It is not uncommon to observe two separate breaks in the curve at the end of the QRS. When in doubt as to which is the real J-point, take the second or rightward point to determine the J-point for 4-codes (see Fig. 7.7 and 7.8). In Fig. 7.9, the J-point defies assignment. The S-wave continues in a smooth curve to the peak of the T-wave. The end of the QRS is determined from where a horizontal tangent from the upper margin of the baseline at the beginning of the previous QRS complex intersects the upward curve. In this example, no J-point depression and no ST segment depression is coded (see Code 9-2, Chap.11) 63

Fig. 7-10

ST segment ST segment

FIGURE 7.10. The J-point marks the end of the QRS and the beginning of the ST segment. The end of the ST segment is sometimes distinct but more often merges imperceptibly with the T-wave. The ST segment is then considered to extend to the peak of the T-wave. In the first example, the ST is exaggeratedly represented as a distinct segment. In the second, the ST segment merges with the T-wave and extends to the peak of T. Both T-waves are positive Fig. 7-11

ST segment

ST segment

FIGURE 7.11. It shows similar types of ST segment to Fig. 7.10, but with both T-waves negative 64

Fig. 7-12

ST segment

ST segment

FIGURE 7.12. The J-point is depressed in the first beat with the ST segment merging into a positive T-wave. The second beat shows the J-point level with the preceding P-R baseline and the ST segment merging into the T-wave

Fig. 7-13

ST segment

ST segment

FIGURE 7.13. The J-point is depressed with the ST segment merging in different forms into a negative T-wave 65

Fig. 7-14 R ST segment flat T wave

J point P

FIGURE 7.14. An ST segment can be associated with a flat T-wave, giving no measurable segment, even though the J-point can be distinguished

Fig. 7-15

perfect curve • no clearly defined ST segment • no J point

FIGURE 7.15. An example of indeterminate ST segment is illustrated. When a near-perfect curve is present (no straight ST segment for at least 2 mm), there is no clearly defined ST segment. With this type of ST-T wave, there is no measurable J-point 66

FIGURES 7.16–7.18. Different levels of J-point displacement are illustrated. The reference for determining J-point displacement is the upper margin of the baseline immediately preceding the QRS complex. In Fig. 7.16, the J-point is depressed; in Fig.7.17, it is elevated. In Fig. 7.18, there is neither elevation nor depression 67

Fig. 7-19

upward sloping ST segment

Fig. 7-20

upward sloping ST segment

Fig. 7-21

upward sloping ST segment

FIGURES 7.19–7.21. The slope of the ST segment is measured from the J-point to the start of the T-wave or to the peak of the T-wave when there is no distinction between the end of the ST segment and the start of the T-wave. The ST segment is upward sloping in all of these figures. The level of the J-point does not determine the slope 68

Fig. 7-22

upward sloping ST segment

J

J

FIGURE 7.22. Remember, where there are two possible J-points, the depression and slope of the ST segment are determined from the second

Fig. 7-23 upward sloping ST segment elevated J point

FIGURE 7.23. It shows the J-point elevated from the P-R baseline and having an upward sloping ST segment 69

Fig. 7-24

U shaped curve - considered an upward sloping ST segment

upward sloping ST segment

FIGURE 7.24. The direction of the ST segment is classified as horizontal, downward, or upward sloping based on the following rule: The segment is not horizontal or downward sloping if any part of it slopes upward. This also applies to curved or U-shaped ST segments. Both ST segments illustrated in this figure are considered upward sloping Fig. 7-25 downward sloping ST segment

FIGURE 7.25. The exception to this rule sometimes occurs when the ST segment is convex upwards. If the amplitude at the end of the ST segment is lower than the J-point, this convex pattern is considered equivalent to a downward sloping ST segment and is so coded 70

Fig. 7-26

upward sloping ST segment

FIGURE 7.26. The convex ST segment is not considered downward sloping because the end of the ST segment is higher or at the same level as the J-point Fig. 7-27

horizontal ST segment

FIGURE 7.27. Both the J-point and ST segment slope are important in determining 4-codes. The J-point is level with the preceding P-R baseline, and there is a horizontal ST segment Fig. 7-28

horizontal ST segment

FIGURE 7.28. The J-point is depressed and there is a horizontal ST segment 71

Fig. 7-29

horizontal ST segment

J

FIGURE 7.29. The J-point can also be elevated with a horizontal ST segment Fig. 7-30

horizontal ST segment

J

J

FIGURE 7.30. Always remember to use the second of the two possible J-points for determining J-point depression and ST segment slope. In the figure there are two apparent J-points with a horizontal ST segment because the second of two possible J-points is taken as the correct J-point Fig. 7-31

downward sloping ST segment no J point depression

J

FIGURE 7.31. The J-point is at the same level as the P-R baseline. Thus, there is a downward sloping ST segment and no J-point depression 72

Fig. 7-32

downward sloping ST segment

J

FIGURE 7.32. The J-point can also be depressed and be followed by a downward sloping ST segment

Fig. 7-33

J

downward sloping ST segment

J

J point depressed

FIGURE 7.33. Again, remember where two possible J-points appear, always use the second J-point to determine depression and ST segment slope Fig. 7-34

downward sloping ST segment

J

FIGURE 7.34. An elevated J-point accompanied by a downward sloping ST segment is shown 73

Fig. 7-35

measurement of J point depression

FIGURE 7.35. The two most important criteria for measuring 4-codes are correct J-point location and ST slope determination. The amplitude of J-point depression is measured vertically to the intersection of a tangent drawn horizontally from the upper margin of the P-R baseline at the onset of QRS Fig. 7-36

measurement of J point depression

FIGURE 7.36. Locate the J-point by constructing a tangent to the ST segment and measuring vertically to the level of the baseline, upper margin Fig. 7-37

measurement of J point depression

FIGURE 7.37. The J-point is depressed and the ST segment is upward sloping 74

FIGURES 7.38 and 7.39. J-point depression is measured in millimeters, the code depending on the degree of depression. The procedure is to code conservatively in case of doubt. The majority of beats in the lead (>50%) should qualify to be coded in that category. Leads III and aVR are ignored in coding ST segments and T-waves because their waves are too variable to be reliable. The first and major 4-code is 4-1-1. To qualify, the J-point must be depressed ≥ 2mm in the majority of beats in any of leads I, II, aVL, aVF, V1–V6. The slope of the ST segment must also be downward sloping as in Fig. 7.38 or horizontal as in Fig. 7.39 75

Fig. 7-40 4-1-2 • in any of leads I, II, aVL, aVF, V1-V6 • 1 mm. £ J point depression < 2 mm. • horizontal ST segment

Fig. 7-41 4-1-2 • in any of leads I, II, aVL, aVF, V1-V6 • 1 mm. £ J point depression < 2 mm. • downward sloping ST segment

FIGURES 7.40 and 7.41. For code 4-1-2, the J-point depression must be ≥1 mm but < 2 mm with the ST segment horizontal or downward sloping in the majority of beats in any of the leads I, II, aVL, V1–V6

76

Fig. 7-42 4-2 • in any of leads I, II, aVL, aVF, V1-V6 • 0.5 mm. £ J point depression < 1 mm. • downward sloping ST segment

Fig. 7-43 4-2 • in any of leads I, II, aVL, aVF, V1-V6 • 0.5 mm. £ J point depression < 1 mm. • horizontal ST segment

FIGURES 7.42 and 7.43. Code 4-2 is similar to the previous codes, only less marked. To qualify, the J-point must be depressed ≥ 0.5 mm but 50%) of beats in any of these leads. This code is different from the previous codes in which it requires that the end of the ST segment must be at least 0.5 mm below the P-R baseline. In Fig. 7.45, even though the baseline is downward sloping, this is not a 4-3 code because the end of the ST segment (here the same as the T-wave nadir) is depressed less than 0.5 mm below the P-R baseline 78

Fig. 7-46

4-4 • any of leads I, II, aVL, V1-V6 • J point depression ≥ 1 mm. • upward sloping ST segment

J

FIGURE 7.46. A 4-4 code is different in concept from the other 4-codes in which the ST segment is upward sloping from a J-point depressed 1 mm or more from the P-R baseline

Fig. 7-47 4-4 • any of leads I, II, aVL, V1-V6 • J point depression ≥ 1 mm. • upward sloping ST segment

J J

FIGURE 7.47. Use the second J-point to determine the amount of ST depression

79

Fig. 7-48

4-4

FIGURE 7.48. Another example of a 4-4 code is a curved, concave ST segment where no straight part of the segment is 2 mm in length. When the trough of such a curve is depressed ≥ 1 mm from the P-R baseline, it should be coded 4-4. To measure the ST depression, measure from the upper margin of the lower point vertically to the upper margin of the P-R baseline Fig. 7-49

4 codes • lead V1

4-1-1

4-1-2

4-2

4-4

FIGURE 7.49. 4-1-1, 4-1-2, 4-2, and 4-4 may be coded in V1, but not a 4-3. In lead aVF, 4-1-1, 4-1-2, and 4-2 are the only possible 4-codes and there are no 4-codes for III or aVR. Most 4-1 through 4-3 coding requires that a 5-code or negative T-wave code be present. This is because in all 4-1 to 4-3 codes the end of the ST segment is depressed and the end of the ST segment is the beginning of the T-wave. Therefore, the onset of the T-wave must be negative and codable. The exceptions are that 4-codes in V1 are coded without 5-codes, in aVF when the QRS is mostly negative and in aVL when the R-wave is < 5 mm Figures 7.50–7.56 show different forms of the T-wave that need to be recognized to code 5-codes correctly 80

Fig. 7-50 negative T wave R

P

T

FIGURE 7.50. The negative T-wave is distinct from the level (isoelectric) ST segment and is ≥1.0 mm below the P-R baseline. It is important to note in the following illustrations that the presence of a negative T-wave is determined by its relation to the top of the preceding P-R segment Fig. 7-51

diphasic T waves

positive - negative type

negative - positive type

FIGURE 7.51. Illustration of the diphasic T-wave, called diphasic because there is both a negative and a positive component to the T-wave. The diphasic T-wave is categorized as positive–negative or negative–positive depending on which component occurs first 81

Fig. 7-52

negative T wave

negative - positive diphasic T wave

FIGURE 7.52. Difference between a simple negative T-wave and a negative–positive diphasic T-wave is shown

Fig. 7-53

negative T waves

R

R

P

P

T

T

FIGURE 7.53. Further examples of negative T-waves are shown. Here, the S-wave is followed by a negative T-wave. In the first beat, the ST segment merges with the T-wave, and in the second, the ST segment is distinct from the T-wave 82

Fig. 7-54

negative T wave

J

ST

FIGURE 7.54. An example of a T-wave in which the ST segment is distinct from the T-wave Fig. 7-55

flat T wave

P

P

FIGURE 7.55. Illustration of a flat T-wave that neither rises nor falls from the baseline Fig. 7-56

measurement of negative T wave

FIGURE 7.56. Having recognized the negative T-wave, its amplitude is determined. To measure a negative T-wave, find the flattest segment of the baseline in the following T-P interval. Measure from this point on the top margin of the baseline vertically to the top of T-wave nadir 83

Fig. 7-57 5-1 • any of leads I, II, V2-V6 • negative T wave amplitude ≥ 5 mm.

5-1

Fig. 7-58

in aVF the QRS must be mainly positive

R height must be ≥ 5 mm. in aVL

FIGURES 7.57 and 7.58. The negative T-wave amplitude is always measured in millimeters, and is measured conservatively. A majority of beats in a lead have to meet the criteria for each code. The 5-codes are also listed in the order of magnitude. The negative T-wave is coded to the most severe or lowest numbered category for which it qualifies in any lead of the set. The greatest negative T-wave code is 5-1. To qualify as 5-1, the T-wave must be ≥5 mm negative in any of leads I, II, V2-V6 (see Fig. 7.57) or in aVL when the R-wave is ≥5 mm, or in aVF when the QRS is mainly positive (see Fig. 7.58), that is, the sum of R-wave amplitudes is larger than the sum of negative deflections (Q- or S-waves) 84

Fig. 7-59 5-1 • any of leads I, II, V2-V6

FIGURE 7.59. The 5-1 criteria are met, even though the ST segment is upward sloping. The T-wave is separate and negative

Fig. 7-60 5-1 • any of leads I, II, V2-V6

FIGURE 7.60. Illustration of another possible 5-1 pattern. Here the ST-J depression is prominent with the ST segment horizontal and depressed ≥5 mm because the end of the ST segment is the beginning of the T-wave, this point is taken to measure the negative T-wave; amplitude, i.e., ≥5 mm to give a 5-1 code 85

Fig. 7-61 5-1 • any of leads I, II, V2-V6 • diphasic T wave

≥ 5mm

FIGURE 7.61. Negative T-wave amplitude in a diphasic T-wave is measured from the top of the level part of the T-P interval to the top of the nadir of the T-wave

Fig. 7-62 5-1 • any of leads I, II, V2-V6 • diphasic T wave

5mm

FIGURE 7.62. This procedure is used for measuring either type of diphasic T-wave, but it is only the negative component of the T-wave that is measured for coding

86

Fig. 7-63

5-2 • any of leads I, II, V2-V6 • 1 mm £ T amplitude < 5 mm.

FIGURE 7.63. A 5-2 code is less prominent than 5-1. To qualify as 5-2, the negative T-wave amplitude must be ≥1 mm but R in lead V1 or V2 • QRS duration < 0.12 sec. in the majority of beats in each of leads I, II, III, aVL, aVF • S wave ≥ 0.25 mm. below the PR baseline in the majority of beats • initial R ≥ 0.25 mm. in the majority of beats • terminal R amplitude ≥ 1 mm. in the majority of beats

FIGURE 9.35. Code 7-3 is for an incomplete right bundle branch block. Two criteria must exist to code a 7-3. First, the QRS duration must R' • S ≥ 0.25 mm.

FIGURE 9.41. Remember as with 7-3 code, for a 7-5 code, the S amplitude must be ≥0.25 mm. Also, both R and R΄amplitudes are measured from the upper margin of the preceding P-R baseline 7-5

Fig. 9-42

• R' < R • R and R' ≥ 0.25 mm.

FIGURE 9.42. In all cases except for 7-5 codes, terminal R amplitude must be ≥1.0 mm (see Chap. 4). For 7-5 code, initial and terminal R΄ amplitude need only be ≥0.25 mm terminal R (definition for 7-5 only)

Fig. 9-43

• a ≥ 0.25 mm • b £ 0.04 sec. • c ≥ 0.25 mm.

b

c

a

FIGURE 9.43. Sometimes, it is difficult to determine whether a terminal R΄-wave is present. It must meet the following conditions: R΄ amplitude ≥0.25 mm, dropping at least 0.25 mm within 0.04 second of its peak, in the majority of beats of the lead in question 127

Fig. 9-44

7-6 • leads I, aVL and V5 or V6 • 0.10 sec. £ QRS duration < 0.12 sec.

FIGURE 9.44. Code 7-6 is for incomplete left bundle branch block. For this code, QRS must be ≥0.10 second and R R

OR

Fig. 9-49

• lead V1 or V2 • QRS mainly upright (R>Q or S) • R peak duration ≥ 0.06 sec. in the majority of beats

OR

Fig. 9-50

• lead I or II • S duration > R duration in all beats

130

Code 7-9 is for the Brugada pattern1,2 and is a combination of persistent ST elevation in the right precordial leads – in at least two of leads V1 to V3. Code 7-3 may or may not be present in addition. Fig. 9-51

7-9-1 V1

V2

V3

FIGURE 9.51. Type 1 Brugada pattern1,2 7-9-1 has a convex (coved) ST segment elevation ≥2 mm plus a negative T-wave with little or no isolelectric (baseline) separation in at least 2 leads of V1-V3 7-9-2

Fig. 9-52 V1

V2

V3

FIGURE 9.52. Type 2 Brugada pattern 7-9-2 has ST segment elevation ≥2 mm plus a positive or diphasic T-wave that results in a “saddle-back” shape in at least 2 leads of V1-V3 131

FIGURE 9.53. Type 3 Brugada pattern 7-9-3 has an ST segment elevation ≤ 1 mm plus a “saddleback” configuration in at least 2 leads of V1-V3

FIGURE 9.54. Code 7-10 for fragmented QRS shows different morphologies of a fragmented QRS on a 12-lead ECG3-6

132

Rules for coding of Fragmented QRS: (1) notching is a sudden change in slope (down or up) of any part of the Q-, R-, or S-wave such that the angle formed is 30% >36% >25% ±36% ±60% ±30% ±36% +25%

E-LVH 1: Minnesota Code 3-0 in reference ECG followed by an ECG with a 3-1in the follow-up ECG, confirmed as a significant increase. E-LVH 2: Minnesota Code 3-0 in reference ECG followed by an ECG with a 3-3 in the follow-up ECG, confirmed as a significant increase. E-LVH 3: Minnesota Code 3-1 in reference ECG, followed by an ECG with a 3-0 in the event ECG, confirmed by a significant decrease. E-LVH 4: Minnesota Code 3-3 in reference ECG, followed by an ECG with a 3-0 in the event ECG, confirmed by a significant decrease. E-LVH 5: Minnesota Code 3-1 in the reference ECG, followed by an ECG with a 3-1 in the event ECG, confirmed by a significant increase or a significant decrease. E-LVH 6 Minnesota Code 3-3 in the reference ECG, followed by an ECG with a 3-3 in the event ECG, confirmed by a significant increase or decrease. (LVH must by confirmed by serial change criteria for E-LVH)

232

TABLE 15.5. Evolving ECG Measures for LVH. Definition

Formula

Cut-Point for LVH

Change Criteria

Sokolow-Lyon Cornell Voltage

SV1 + RV5 or RV6 RaVL + SV3

3500 µV 2800 µV (men) 2200 µV (women) 243.6 µV.s 17900 µV 1747.2 µV.s

>900 µV >400 µV >400 µV >41 µV. s. >2319 µV >355.6 µV. s.

Cornell Product (RaVL + SV3) ´ QRS duration Sum of 12 leads 12-lead QRS sum (except lead aVR) 12 leads Product 12-lead QRS sum ´ QRS duration Units: µV, microvolts for Q.R.S of amplitudes µV .s. microvolts.seconds for the product of ECG voltage and QRS duration.

Serial Change for Acute Myocardial Infarction A subset of evolving Q and evolving ST-T were labeled as Evolving Diagnostic ECG or Positive ECG in the AHA Scientific Statement for Case Definitions for Acute Coronary Heart Disease in Epidemiology and Clinical Research Studies.1 Evolving Q1Q4 are labeled evolving diagnostic for the AHA epidemiologic case definition of Acute Myocardial Infarction (AMI). Any of these document a definite AMI. Evolving Q5-Q7, evolving STE 1-5, or EBBB1 document “positive ECG.” These serial change criteria have been used in many epidemiologic studies and clinical trials,1 and have been validated in the Multiple Risk Factor Intervention Trial and the Minnesota Heart Study.2,3 There are seven criteria for Q-wave MI and nine for ST-T-wave evolution. Evolving Q-waves have adjusted relative risks about 4.0, and evolving ST-T waves have an adjusted relative risk from 1.5–2.0. These risk levels persist for both silent and symptomatic ischemic cardiac events. Categories of Significant ECG Waveform Change Determined by Minnesota Code Serial Comparison Evolving Diagnostic Q-code pattern with or without ST-T wave changes (ED) Evolving ST-T wave without evolving Q-code pattern (EV) Evolving Bundle Branch Block (E-BBB) Evolving Left Ventricular Hypertrophy (E-LVH) When classifying Minnesota Code changes into the above categories, it is important to remember the following: • The reference ECG is the reference record for non-hospital visits; the reference ECG is the earliest hospital record for in-hospital acute events. • An equivocal Minnesota Q-code is any 1-3-x code. • A diagnostic Minnesota Q-code is any 1-1-x or any 1-2-x. • All ED patterns are confirmed as significant increase by serial comparison. • All EV patterns are confirmed as significant increases or decreases by serial comparison. • All E-BBB are confirmed as significant increases by serial comparisons. • All E-LVH are confirmed as significant increases or decreases by serial comparison criteria. 233

REFERENCE ECG

EVENT ECG

FIGURE 15.1. Minnesota Code 1-1-1. Reference ECG shows initial R-waves V1-V3. Event ECG has 1-1-1 code in V3. Significant pattern change IS confirmed because ≥ 1mm Rwave amplitude decrease occurs between the ECGs in V3 (EVQ1)

REFERENCE ECG

EVENT ECG

FIGURE 15.2. Minnesota Code 1-1-1. Reference ECG shows initial R-waves V2. Event ECG shows no initial R-wave in lead V2 (QR complex) and a 1-1-1 code. Significant ECG pattern change IS NOT confirmed because < 1 mm R-wave amplitude decrease occurs between the reference and event ECG in V2 (EVQ0)

234

REFERENCE ECG

EVENT ECG

FIGURE 15.3. Minnesota Code 1-1-1. Reference ECG shows a small noncodable Q-waves in lead II. Event ECG shows a 1-1-1 in lead II. Significant ECG pattern change IS confirmed in lead II because there is ≥ 1mm R-wave amplitude decrease between reference ECG and event ECG in lead II (EVQ1)

FIGURE 15.4. Minnesota Code 1-1-2. Reference ECG shows initial R-waves V1–V3. Event ECG shows tiny initial R-wave in lead V1 but not in the majority of beats), and QS complex in V2–V3. Lead V1 meets 1-1-2 code criteria. Significant pattern change IS confirmed because ≥ 1 mm R-wave amplitude decrease occurs between the reference and event ECG in lead V1 (EVQ1)

235

EVENT ECG

REFERENCE ECG

FIGURE 15.5. Minnesota Code 1-1-2. Reference ECG shows QS complex in V1. Event ECG has QR pattern in V1, meeting 1-1-2 code criteria. Significant ECG pattern change IS NOT confirmed because < 50% increase in Q/R occurs between the reference and Event ECG’s in lead V1. (The Q/R of reference ECG is infinite because of QS complex.) (EVQ0) REFERENCE ECG

EVENT ECG

FIGURE 15.6. Minnesota Code 1-1-2. Reference ECG shows tiny initial R-wave in V1. Event ECG has QR complex in V1, meeting 1-1-2 code criteria. Significant ECG pattern change IS NOT confirmed because 180° to adjust to the minimal angle. (D) Spatial T-wave axis based on areas of the wave components of the QRS complex and T wave Step 1. Using a matrix transformation algorithm from the digital files of the 12-lead ECG signals to generate the X, Y, and Z leads. First calculate the mean X, Y, and Z lead amplitudes for QRS and T waves in their respective time windows. The spatial T-axis is an estimate of the deviation from the normal reference direction (1/√3=0.5774. X = 1/√3, Y = 1/√3, and Z = −1/√3, where x, y, and z are the unit vector components in X, Y, and Z directions). Thus, this reference direction is 45° anteriorly, with a 45° angle from the +Y axis in the frontal and sagittal plane projections. Step 2. Calculate the spatial magnitude of the T vector. Txyz = (T x2 + T y2 + T z2)0.5 Step 3. The algorithm Spatial T-wave axis Spatial T axis = ACOS[(0.5774 * Tx) + (0.5774 * Ty) + (0.5774 * Tz)]/Txyz where “ACOS” is the inverse cosine. If spatial T axis is obtained in radians, as in Excel, they are converted to degrees by multiplying the inverse cosine by the factor 57.3.

FIGURE 16.1. Spatial QRS/T angle (matrix) = 125; spatial QRS/T angle (simple) = 127; frontal QRS/T angle (frontal) = 124; spatial T-wave axis = 63

265

FIGURE 16.2. Spatial QRS/T angle (matrix) = 141; spatial QRS/T angle (simple) = 138; frontal QRS/T angle (frontal) = 114; spatial T-wave axis = 48

Heart Rate Variability Heart rate variability (HRV) analysis is designed for quantitative assessment of the autonomic nervous system (ANS). Reduced HRV in ultrashort standard ECG tracings indicating time domain but not frequency has been associated in numerous studies with mortality risk.6-13 HRV analysis is based on measuring variability in heart rate, specifically, variability in intervals between R waves – “RR intervals”. Originally, HRV was assessed manually from the calculation of the mean R-R interval, and its standard deviation was measured on short-term (e.g. 5 minutes) ECG. The smaller the standard deviation in R-R intervals, the lower is the HRV. To date, HRV also can be assessed from an ultrashort ECG strips (one or multiple 10 second ECGs). There are many different types of arithmetic manipulations of R-R intervals, which have been used to represent HRV. The basic parameters include the standard deviations (SD) of all normal mean R-R intervals (SDNN) and square root of the mean of the difference of successive R-R intervals (RMSSD). For short-term ECG recordings ( 0.40 and < 0.60; Good: > 0.60 and < 0.75; Excellent: > 0.75). Below is an example of agreement for Minnesota code 1 between two coders.

Second Report

1:0 1:1 1:2 1:3 Total

1:0 39 0 0 0 39

First Report 1:1 1:2 1:3 0 0 1 2 0 0 0 3 0 0 0 8 2 3 9

Total 40 2 3 8 53

Kappa Statistics Statistic

Value

ASE

95%

Confidence Limits

Simple Kappa Weighted Kappa

0.9545 0.9428

0.0452 0.0564

0.8658 0.8322

1.0000 1.0000

Quantitative Variables Disagreements between replicate determinations often have skewed distributions – i.e., most pairs of readings may show relatively small disagreements, but a few may vary widely. 272

Ordinary statistical summaries are based on variance estimates, which are very sensitive to a few outlying observations. It is therefore as well to examine the actual distribution of disagreements on at least a sample of readings and calculate variance, etc., only if the distribution is normal or approximately so. Summarizing the repeatability of a series of repeated measurements such as heart rate, P-R interval, QRS duration, and JT and QT intervals by SAS3 Procedures of MEANS, CORR, and TTEST should be a suitable way to produce a mean of all first readings, mean of all second readings, correlation coefficients, and standard deviation of differences between pairs of readings. The following example is a plotted graph for heart rate measurement by Excel graphics software which first selects paired heart rate measurements to test, then chooses a Chart type XY (scatter) from Chart Wizard in Excel then draws a central line for an exact match between two measurements, and adds two other lines – either five up or five down to give the accepted range for this ECG parameter.

Quality Control Testing -- Visual ECG Reading for Heart Rate 110

Heart Rate (/min) - Second Reading

105 100 95 90 85 80 75 70 65 60 55 50 45 45

50

55

60

65

70

75

80

85

90

95

100

105

110

Heart Rate (/min) - Standard (First Reading)

The Minimum Accepted Standard for Repeatability Tests The difference between coders and the standard for heart rate should be less than ± 5 beats/ min, the difference for P-R interval and QRS duration should be less than ± 10 ms, the difference for JT and QT intervals should be less than ± 20 ms, and the difference for QTI and JTI should be less than ± 5%. Repeatability of MI and continuous measurement coding from our Reading Center, EPICARE, in the recent decade are shown in Tables 1 to 6. 273

(A) Internal Quality Control Analysis between the ECG Coder and Standard (Quarterly) TABLE 17.1. The Agreement for Myocardial Infarction by Minnesota Code (MC-MI – see appendix A). Final Adjudicated Code (Standard) Initial Visual Code MC-MI = 0 MC-MI = 1 Total

MC-MI = 0

MC-MI = 1

Total

34 0 34

1 18 19

35 18 53

Simple Kappa Coefficient Kappa ASE 95% Lower Conf Limit 95% Upper Conf Limit

0.9585 0.0411 0.8782 1.0000

TABLE 17.2. The Agreement for Myocardial Infarction by Novacode (NC-MI – see appendix B). Final Adjudicated Code (Standard) Initial Visual Code NC-MI = 0 NC-MI = 1 Total

NC-MI = 0

NC-MI = 1

Total

36 1 37

2 14 16

38 15 53

Simple Kappa Coefficient Kappa ASE 95% Lower Conf Limit 95% Upper Conf Limit

0.8633 0.0765 0.7134 1.0000

TABLE 17.3. Correlation Analysis Between the Coder and Standard. Pearson Correlation

Coefficients

Heart Rate P-R Interval QRS Duration Q-T Interval QTI QRS Axis

0.9981 0.9829 0.8092 0.9638 0.9064 0.9803 274

TABLE 17.4. T-Test for the Difference Between the Coder and Standard. Variables

Mean

SD

P Value

Heart Rate PR interval QRS Duration QT interval QTI QRS Axis

0.26 0.19 0.19 1.43 0.52 – 0.06

0.68 5.71 7.00 9.07 2.37 7.9

0.0069 0.8110 0.8452 0.2550 0.1159 0.9589

(B) Intra-coder Quality Control Analysis between of an ECG coder (From 2000 – 2008) TABLE 17.5. Kappa for Myocardial Infarction by Minnesota Code & Novacode – (see Appendies A and B). Years

MC-MI

NC-MI

2000 2001 2002 2003 2004 2005 2006 2007 2008

0.9077 1.0000 0.9529 0.9113 0.9548 0.8643 0.8586 0.9548 0.9207

0.8100 0.8383 0.8628 0.8129 0.9459 0.9170 0.9462 0.8525 0.8591

TABLE 17.6. The Correlation for ECG Measurements with year 2008 Year

Heart rate

PR interval

QRS duration

QT interval

2001 2002 2003 2004 2005 2006 2007

0.9961 0.9977 0.9986 0.9907 0.9962 0.9979 0.9980

0.9965 0.9706 0.9733 0.9784 0.9562 0.9662 0.9681

0.8839 0.9361 0.9164 0.9454 0.9326 0.9379 0.9380

0.9087 0.9168 0.8787 0.9322 0.9145 0.9273 0.9272

Quality Control of Electronically Processed ECGs The variability of current, directly electronically transmitted ECG source data will be 0% due to the digital nature of the stored and transmitted data. This was not always so with digital data transmitted on cassettes with wave averaging analysis.4 With current systems, the median (most representative) P-QRS-T complex produced is used by EPICARE to classify ECG findings according to the Minnesota Code and Novacode algorithms. Interval measurements by the program are ideal for the assessment of time trends. The measurements are very robust, with the exception of the rare occurrences of missed detection of low amplitude P waves and misplacement of the T wave at the end of the U wave when T-U 275

fusion takes place. Every ECG is checked for these possible wave detection errors and an interactive computer graphics terminal with special software is used to correct these errors. It can be categorically stated that when the global onsets and offsets of ECG waves are properly detected, wave amplitude measurements used to assign Minnesota Codes are invariable, done with a precision far superior to that possible with visual inspection (even with fourfold magnification). As with the use of any computer-ECG program, built-in safeguards have to be in place to protect against software changes that may produce secular time trends in ECG measurements due to possible software upgrades during a prolonged period of an observational study. This task can be achieved by using a test library of say, 200+ ECGs enriched with abnormal ECG patterns (MIs, conduction defects etc.). The ECGs from this library should be processed using the Minnesota Code classification algorithms in the beginning of the study and annually. Contingency tables demonstrating the invariability of classification can then be produced for each Minnesota Code classification category. Trend Analysis The digital “raw” measurements for PR QT interval and QRS duration should be maintained by a study Coordinating Center to check for unsuspected technological, recording procedural changes, or editing changes that might occur during the course of a long recruitment period as in some population based epidemiologic studies or clinic-based clinical trials. Monitoring of QRS, QT and PR intervals will reflect seasonal variation due to heart rate (HR) sensitive intervals, such as QT. With HR correction of QT, trend analysis based on electronic measurements (obtained from the electronically transmitted ECGs from the field centers or clinics) will provide data on aging changes due to biological alteration of these intervals with time. More importantly, any sudden unexplained deviation from a steady state in these parameters would signal procedural or software alteration (at local electrocardiographs or central analytic programs) that can be investigated and corrected by the study directorate. Such monitoring may uncover problems not otherwise apparent from other QC monitoring. For the same reasons, QRS and T axis should be monitored for trend analysis reflecting frontal plane voltage changes. References 1. Streiner DL, Norman GR. Health Measurement Scales. 4th ed. Oxford: Oxford University Press; 1994. 2. Altman DG. Practical Statistics for Medical Research. London: Chapman and Hall; 1991. 3. SAS Version 9.1: The FREQ Procedure. Cary, North Carolina. SAS Institute, Inc., 4. Rautaharju PM, Broste SK, Prineas RJ, et al. Quality control procedures for the resting electrocardiogram in the Multiple Risk Factor Intervention Trial. Controlled Clin Trials. 1986;7:46S-65S.

276

Appendix A MINNESOTA CODE 2009 Q and QS Patterns Do not code in the presence of WPW code 6-4-1, or artificial pacemaker code 6-8 or code 6-1, 8-2-1. 8-2-2, or 8-4-1 with a heart rate ≥ 140. To qualify as a Q-wave, the deflection should be at least 0.1 mV (1 mm in amplitude). Anterolateral Site (leads I, aVL, V6) 1-1-1 Q/R amplitude ratio ≥ 1/3, plus Q duration ≥ 0.03 s in lead I or V6. 1-1-2 Q duration ≥ 0.04 s* in lead I or V6. 1-1-3 Q duration ≥ 0.04 s plus R amplitude ≥ 3 mm in lead aVL. 1-2-1 Q/R amplitude ratio ≥ 1/3, plus Q duration ≥ 0.02 s and < 0.03 s in lead I or V6. 1-2-2 Q duration ≥ 0.03 s and < 0.04 s in lead I or V6. 1-2-3 QS pattern in lead I. Do not code in the presence of 7-1-1. 1-3-1 Q/R amplitude ratio ≥ 1/5 and < 1/3, plus Q duration ≥ 0.02 s and < 0.03 s in lead I or V6. 1-3-3 Q duration ≥ 0.03 s and < 0.04 s, plus R amplitude ≥ 3 mm in lead aVL. 1-3-81 Initial R amplitude decreasing to 2 mm or less in every beat (and absence of codes 3-2, 7-1-1, 7-2-1, or 7-3) between V5 and V6. (All beats in lead V5 must have an initial R > 2 mm.) Posterior (inferior) site (leads II, III, aVF) 1-1-1 Q/R amplitude ratio ≥ 1/3, plus Q duration ≥ 0.03 s in lead II. 1-1-2 Q duration ≥ 0.04 s in lead II. 1-1-4 Q duration ≥ 0.05 s in lead III, plus a Q-wave amplitude ≥ 1.0 mm in the majority of beats in lead aVF. 1-1-5 Q duration ≥ 0.05 s in lead aVF. 1-2-1 Q/R amplitude ratio ≥ 1/3, plus Q duration ≥ 0.02 s and < 0.03 s in lead II. 1-2-2 Q duration ≥ 0.03 s and < 0.04 s in lead II. 1-2-3 QS pattern in lead II. Do not code in the presence of 7-1-1. 1-2-4 Q duration ≥ 0.04 s and < 0.05 s in lead III, plus a Q-wave ≥ 1.0 mm amplitude in the majority of beats in aVF. 1-2-5 Q duration ≥ 0.04 s and < 0.05 s in lead aVF. 1-3-1 Q/R amplitude ratio ≥ 1/5 and < 1/3, plus Q duration ≥ 0.02 s and < 0.03 s in lead II. 1-3-4 Q duration ≥ 0.03 s and < 0.04 s in lead III, plus a Q-wave ≥ 1.0 mm amplitude in the majority of beats in lead aVF. 1-3-5 Q duration ≥ 0.03 s and < 0.04 s in lead aVF. 1-3-6 QS pattern in each of leads III and aVF. (Do not code in the presence of 7-1-1.) 1-3-72 QS pattern in lead aVF only. (Do not code in the presence 7-1-1) * s = second

277

Anterior Site (leads V1, V2, V3, V4, V5) 1-1-1 Q/R amplitude ratio ≥ 1/3 plus Q duration ≥ 0.03 s in any of leads V2, V3, V4, V5. 1-1-2 Q duration ≥ 0.04 s in any of leads V1, V2, V3, V4, V5. 1-1-6 QS pattern when initial R-wave is present in adjacent lead to the right on the chest, in any of leads V2, V3, V4, V5, V6. 1-1-7 QS pattern in all of leads V1-V4 or V1-V5. 1-2-1 Q/R amplitude ratio ≥ 1/3 plus Q duration ≥ 0.02 s and < 0.03 s, in any of leads V2, V3, V4, V5. 1-2-2 Q duration ≥ 0.03 s and < 0.04 s in any of leads V2, V3, V4, V5. 1-2-7 QS pattern in all of leads V1, V2, and V3. (Do not code in the presence of 7-1-1.) 1-3-1 Q/R amplitude ratio ≥ 1/5 and < 1/3, plus Q duration ≥ 0.02 s and < 0.03 s in any of leads V2, V3, V4, V5. 1-3-2 QS pattern in lead V1 and V2. (Do not code in the presence of 3-1 or 7-1-1.) 1-3-81 Initial R amplitude decreasing to 2.0 mm or less in every beat (and absence of codes 3-2, 7-1-1, 7-2-1, or 7-3) between any of leads V2 and V3, V3, and V4, or V4 and V5. (All beats in the lead immediately to the right on the chest must have an initial R > 2 mm.) QRS Axis Deviation Do not code in presence of low-voltage QRS code 9-1, WPW 6-4-1, artificial pacemaker code 6-8, ventricular conduction defects 7-1-1, 7-2-1, 7-4, or 7-8. 2-1

2-2

2-3

2-4

2-5

Left. QRS axis from –30° through –90° in leads I, II and III. (The algebraic sum of major positive and major negative QRS waves must be zero or positive in I, negative in III, and zero or negative in II.) Right. QRS axis from +120° through –150° in leads I, II, and III. (The algebraic sum of major positive and major negative QRS waves must be negative in I, and zero or positive in III, and in I must be one-half or more of that in III.) Right (optional code when 2-2 is not present). QRS axis from +90° through +119° in leads I, II, and III. (The algebraic sum of major positive and major negative QRS waves must be zero or negative in I and positive in II and III.) Extreme axis deviation (usually S1, S2, S3 pattern). QRS axis from –90° through –149° in leads I, II and III. (The algebraic sum of major positive and major negative QRS waves must be negative in each of leads I, II, and III.) Indeterminate axis. QRS axis approximately 90° from the frontal plane. (The algebraic sum of major positive and major negative QRS waves is zero in each of leads I, II and III, or the information from these three leads is incongruous.)

High Amplitude R Waves Do not code in the presence of codes 6-4-1, 6-8, 7-1-1, 7-2-1, 7-4, or 7-8. 3-1

Left: R amplitude > 26 mm in either V5 or V6, or R amplitude > 20.0 mm in any of leads I, II, III, aVF, or R amplitude > 12.0 mm in lead aVL measured only on second to last complete normal beat. 278

3-2

3-3 3-4

Right: R amplitude ≥ 5.0 mm and R amplitude ≥ S amplitude in the majority of beats in lead V1, when S amplitude is > R amplitude somewhere to the left on the chest of V1 (codes 7-3 and 3-2, if criteria for both are present). Left (optional code when 3-1 is not present): R amplitude > 15.0 mm but ≤ 20.0 mm in lead I, or R amplitude in V5 or V6, plus S amplitude in V1 > 35.0 mm. Criteria for 3-1 and 3-2 both present.

ST Junction (J) and Segment Depression Do not code in the presence of codes 6-4-1, 6-8, 7-1-1, 7-2-1, 7-4, or 7-8. When 4-1, 4-2, or 4-3 is coded, then a 5-code most often must also be assigned except in lead V1. Anterolateral Site (leads I, aVL, V6) 4-1-1 STJ depression ≥ 2.0 mm and ST segment horizontal or downward sloping in any of leads I, aVL, or V6. 4-1-2 STJ depression ≥ 1.0 mm but < 2.0 mm, and ST segment horizontal or downward sloping in any of leads I, aVL, or V6. 4-2 STJ depression ≥ 0.5 mm but < 1.0 mm and ST segment horizontal or downward sloping in any of leads I, aVL, or V6. 4-3 No STJ depression as much as 0.5 mm, but ST segment downward sloping and segment or T-wave nadir ≥ 0.5 mm below P-R baseline, in any of leads I, aVL, or V6. 4-4 STJ depression ≥ 1.0 mm and ST segment upward sloping or U-shaped, in any of leads I, aVL, or V6. Posterior (inferior) Site (leads II, III, aVF) 4-1-1 STJ depression ≥ 2.0 mm and ST segment horizontal or downward sloping in lead II or aVF. 4-1-2 STJ depression ≥ 1.0 mm but < 2.0 mm and ST segment horizontal or downward sloping in lead II or aVF. 4-2 STJ depression ≥ 0.5 mm but < 1.0 mm and ST segment horizontal or downward sloping in lead II or aVF. 4-3 No STJ depression as much as 0.5 mm, but ST segment downward sloping and segment or T-wave nadir ≥ 0.5 mm below P-R baseline in lead II. 4-4 STJ depression ≥ 1.0 mm and ST segment upward sloping, or U-shaped, in lead II. Anterior Site (leads V1, V2, V3, V4, V5) 4-1-1 STJ depression ≥ 2.0 mm and ST segment horizontal or downward sloping in any of leads V1, V2, V3, V4, V5. 4-1-2 STJ depression ≥ 1.0 mm but < 2.0 mm and ST segment horizontal or downward sloping in any of leads V1, V2, V3, V4, V5. 4-2 STJ depression ≥ 0.5 mm but < 1.0 mm and ST segment horizontal or downward sloping in any of leads V1, V2, V3, V4, V5. 4-3 No STJ depression as much as 0.5 mm, but ST segment downward sloping and segment or T-wave nadir ≥ 0.5 mm below P-R baseline in any of leads V2, V3, V4, V5. 4-4 STJ depression ≥ 1.0 mm and ST segment upward sloping or U-shaped in any of leads V1, V2, V3, V4, V5. 279

T-Wave Items Do not code in the presence of codes 6-4-1, 6-8, 7-1-1, 7-2-1, 7-4, or 7-8. Anterolateral Site (leads I, aVL, V6) 5-1 T amplitude negative 5.0 mm or more in either of leads I, V6, or in lead aVL when R amplitude is ≥ 5.0 mm. 5-2 T amplitude negative or diphasic (positive–negative or negative–positive type) with negative phase at least 1.0 mm but not as deep as 5.0 mm in lead I or V6, or in lead aVL when R amplitude is ≥ 5.0 mm. 5-3 T amplitude zero (flat), or negative, or diphasic (negative–positive type only) with less than 1.0 mm negative phase in lead I or V6, or in lead aVL when R amplitude is ≥ 5.0 mm. 5-4 T amplitude positive and T/R amplitude ratio < 1/20 in any of leads I, aVL, V6; R wave amplitude must be ≥ 10.0 mm. Posterior (Inferior) Site (leads II, III, aVF) 5-1 T amplitude negative 5.0 mm or more in lead II, or in lead aVF when QRS is mainly upright. 5-2 T amplitude negative or diphasic with negative phase (negative–positive or positive– negative type) at least 1.0 mm but not as deep as 5.0 mm in lead II, or in lead aVF when QRS is mainly upright. 5-3 T amplitude zero (flat), or negative, or diphasic (negative-positive type only) with less than 1.0 mm negative phase in lead II; not coded in lead aVF. 5-4 T amplitude positive and T/R amplitude ratio < 1/20 in lead II; R wave amplitude must be ≥ 10.0 mm. Anterior Site (leads V2, V3, V4, V5) 5-1 T amplitude negative 5.0 mm or more in any of leads V2, V3, V4, V5. 5-2 T amplitude negative, or diphasic (negative–positive or positive–negative type) with negative phase at least 1.0 mm but not as deep as 5.0 mm, in any of leads V2, V3, V4, V5. 5-3 T amplitude zero (flat), or negative, or diphasic (negative–positive type only) with less than 1.0 mm negative phase, in any of leads V3, V4, V5. 5-4 T amplitude positive and T/R amplitude ratio < 1/20 in any of leads V3, V4, V5; R wave amplitude must be ≥ 10.0 mm. A-V Conduction Defect 6-1

Complete (third degree) A-V block (permanent or intermittent) in any lead. Atrial and ventricular complexes independent, and atrial rate faster than ventricular rate, with ventricular rate < 60. 6-2-1 Mobitz Type II (occurrence of P-wave on time with dropped QRS and T). 6-2-2 Partial (second degree) A-V block in any lead (2:1 or 3:1 block). 6-2-3 Wenckebach’s Phenomenon (P-R interval increasing from beat to beat until QRS and T dropped). 280

6-3 P-R (P-Q) interval ≥ 0.22 s in the majority of beats in any of leads I, II, III, aVL, aVF. 6-4-1 Wolff-Parkinson-White Pattern (WPW), persistent. Sinus P-wave. P-R interval < 0.12 s, plus QRS duration ≥ 0.12 s, plus R peak duration ≥ 0.06 s, coexisting in the same beat and present in the majority of beats in any of leads I, II, aVL, V4, V5, V6. (6-4-1 suppresses 1-2-3, 1-2-7, 1-3-2, 1-3-6, 1-3-8, all 3, 4, 5, 7, 9-2, 9-4, 9-5 codes.) 6-4-2 WPW Pattern, intermittent. WPW pattern in ≤ 50% of beats in appropriate leads. 6-5 Short P-R interval. P-R interval < 0.12 s in all beats of any two of leads I, II, III, aVL, aVF. 6-6 Intermittent aberrant atrioventricular conduction. P-R > 0.12 s (except in presence of 6-5 or heart rate greater than 100), and wide QRS complex > 0.12 s, and normal P-wave when most beats are sinus rhythm. (Do not code in the presence of 6-4-2.) 6-8 Electronic pacemaker. Ventricular Conduction Defect 7-1-1 Complete left bundle branch block (LBBB). (Do not code in presence of 6-1, 6-4-1, 6-8, 8-2-1 or 8-2-2.) QRS duration ≥ 0.12 s in a majority of beats (of the same QRS pattern) in any of leads I, II, III, aVL, aVF, plus R peak duration ≥ 0.06 s in a majority of beats (of the same QRS pattern) in any of leads I, II, aVL, V5, V6. (7-1-1 suppresses 1-2-3, 1-2-7, 1-3-2, 1-3-6, 1-3-7, 1-3-8, all 2, 3, 4, 5, 9-2, 9-4, 9-5 codes. If any other codable Q-wave coexists with the LBBB pattern, code the Q and diminish the 7-1-1 code to a 7-4 code.) 7-1-2 Intermittent left bundle branch block. Same as 7-1-1 but with presence of normally conducted QRS complexes of different shape than the LBBB pattern. 7-2-1 Complete right bundle branch block (RBBB). (Do not code in the presence of 6-1, 6-4-1, 6-8, 8-2-1 or 8-2-2.) QRS duration ≥ 0.12 s in a majority of beats (of the same QRS pattern) in any of leads I, II, III, aVL, aVF, plus: R΄ > R in V1; or QRS mainly upright, plus R peak duration ≥ 0.06 s in V1 or V2; or S duration > R duration in all beats in lead I or II. (Suppresses 1-3-8, all 2-, 3-, 4-and 5-codes, 9-2, 9-4, 9-5.) 7-2-2 Intermittent right bundle branch block. Same as 7-2-1 but with presence of normally conducted QRS complexes of different shape than the RBBB pattern. 7-3 Incomplete right bundle branch block. QRS duration < 0.12 s in each of leads I, II, III, aVL, aVF, and R΄ > R in either of leads V1, V2 (Code as 3-2 in addition if those criteria are met. 7-3 suppresses code 1-3-8.) 7-4 Intraventricular block. QRS duration ≥ 0.12 s in a majority of beats in any of leads I, II, III, aVL, aVF. (7-4 suppresses all 2, 3, 4, 5, 9-2, 9-4, 9-5 codes.) 7-5 R-R΄ pattern in either of leads V1, V2 with R΄ amplitude ≤ R. 7-6 Incomplete left bundle branch block. (Do not code in the presence of any codable Q- or QS-wave.) QRS duration ≥ 0.10 s and < 0.12 s in the majority of beats of each of leads I, aVL, and V5 or V6. 7-7 Left anterior hemiblock (LAH). QRS duration < 0.12 s in the majority of beats in leads I, II,III, aVL, aVF, plus Q-wave amplitude ≥ 0.25 mm and < 0.03 s duration in lead I or aVL, plus left axis deviation of –45° or more negative. (In presence of 7-2, code 7-8 if axis is < – 45° and the Q-wave in lead I meets the above criteria.) 7-8 Combination of 7-7 and 7-2. 281

7-9-12 Type 1 Brugada pattern convex (coved) ST segment elevation ≥ 2 mm plus T-wave negative with little or no isolelectric (baseline) separation in at least 2 leads of V1-V3. 2 7-9-2 Type 2 Brugada pattern ST segment elevation ≥ 2 mm plus T-wave positive or diphasic that results in a “saddle-back” shape in at least 2 leads of V1-V3. 2 7-9-3 Type 3 Brugada pattern. 7-2-1 plus ST segment elevation ≤ 1 mm plus a “saddle-back” configuration in at least 2 leads of V1–V3. 2 7-10 Fragmented QRS. Arrhythmias 8-1-1 Presence of any atrial or junctional premature beats. 8-1-2 Presence of any ventricular premature beats. 8-1-3 Presence of both atrial and/or junctional premature beats and ventricular premature beats. 8-1-4 Wandering atrial pacemaker. 8-1-5 Presence of 8-1-2 and 8-1-4. 8-2-1 Ventricular fibrillation or ventricular asystole. 8-2-2 Persistent ventricular (idioventricular) rhythm. 8-2-3 Intermittent ventricular tachycardia. Three or more consutive ventricular premature beats occurring at a rate ≥ 100. This includes more persistent ventricular tachycardia. 8-2-4 Ventricular parasystole (should not be coded in presence of 8-3-1). 8-3-1 Atrial fibrillation (persistent). 8-3-2 Atrial flutter (persistent). 8-3-3 Intermittent atrial fibrillation (code if 3 or more clear-cut, consutive sinus beats are present in any lead). 8-3-4 Intermittent atrial flutter (code if 3 or more clear-cut, consutive sinus beats are present in any lead). 8-4-1 Supraventricular rhythm persistent. QRS duration < 0.12 s; and absent P-waves or presence of abnormal P-waves (inverted or flat in II, III and aVF); and regular rhythm. 8-4-2 Supraventricular tachycardia intermittent. Three consutive atrial or junctional premature beats occurring at a rate ≥ 100. 8-5-1 Sinoatrial arrest. Unexpected absence of P, QRS and T, plus a R-R interval at a fixed multiple of the normal interval, ±10%. 8-5-2 Sinoatrial block. Unexpected absence of P, QRS and T, preceded by progressive shortening of P-P intervals. (R-R interval at a fixed multiple of the normal interval, ± 10%.) 8-6-1 A-V dissociation with ventricular pacemaker (without capture). Requires: P-P and R-R occur at variable rates with ventricular rate as fast as or faster than the atrial rate, plus variable P-R intervals, plus no capture beats. 8-6-2 A-V dissociation with ventricular pacemaker (with capture). 8-6-3 A-V dissociation with atrial pacemaker (without capture). 8-6-4 A-V dissociation with atrial pacemaker (with capture). 8-7 Sinus tachycardia (≥100/min). 8-8 Sinus bradycardia (≤50/min). 8-9 Other arthythmias. Heart rate may be recorded as a continuous variable. 282

ST Segment Elevation Do not code in the presence of codes 6-4-1, 6-8, 7-1-1, 7-2-1, 7-4, or 7-8. Anterolateral Site (leads I, aVL, V6) 9-2 ST segment elevation ≥ 1.0 mm in any of leads I, aVL, V6. Posterior (Inferior) Site (leads II, III, aVF) 9-2 ST segment elevation ≥ 1.0 mm in any of leads II, III, aVF. Anterior site (Leads V1, V2, V3, V4, V5) 9-2 ST segment elevation ≥ 1.0 mm in lead V5 or ST segment elevation ≥ 2.0 mm in any of leads V1, V2, V3, V4. Miscellaneous Items 9-1

Low QRS amplitude. QRS peak-to-peak amplitude < 5 mm in all beats in each of leads I, II, III, or < 10 mm in all beats in each of leads V1, V2, V3, V4, V5, V6. (Check calibration before coding.) 9-3 P-wave amplitude ≥ 2.5 mm in any of leads II, III, aVF, in a majority of beats. 9-4-1 QRS transition zone at V3 or to the right of V3 on the chest. (Do not code in the presence of 6-4-1, 6-8, 7-1-1, 7-2-1, 7-4, or 7-8.) 9-4-2 QRS transition zone at V4 or to the left of V4 on the chest. (Do not code in the presence of 6-4-1, 6-8, 7-1-1, 7-2-1, 7-4, or 7-8.) 9-5 T-wave amplitude > 12 mm in any of leads I, II, III, aVL, aVF, V1, V2, V3, V4, V5, V6. (Do not code in the presence of 6-4-1, 6-8, 7-1-1, 7-2-1, 7-4, or 7-8.) 9-62 Notched and widened P wave (duration ≥ 0.12 s.) in frontal plane (usually lead II), and/or deep negative component to the P wave in lead V1 duration ≥ 0.04 s. and depth ≥ 1 mm. 9-7-12 Definite Early Repolarization.STJ elevation ≥ 1mm in the majority of beats, T wave amplitude≥ 5 mm, prominent J point, upward concavity of the ST segment, and a distinct notch or slur on the down-stroke of the R wave in any of V3 –V6, OR STJ elevation ≥ 2 mm in the majority of beats and T wave amplitude ≥ 5 mm, prominent J point and upward concavity of the ST segment in any of V3 –V6. 2 9-7-2 Probable Early Repolarization. STJ elevation ≥ 1 mm in the majority of beats, prominent J point, and upward concavity of the ST segment in any of V3 –V6 and T wave amplitude ≥ 8 mm in any of the leads V3 –V6. 9-8-12 Uncorrectable lead reversal. 9-8-23 Poor Quality/Technical problems which interfere with coding. 9-8-32 Correctable lead reversal i. Correctable limb lead connection error ii. Correctable chest lead connection error in V1-V3 iii. Correctable chest lead connection error in V4-V6 iv. Correctable other chest lead connection error 3 9-8-4 Technical problems that do not interfere with coding.

283

Incompatible Codes The codes in the left column suppress codes in the right column. Code

Suppresses this code(s)

All Q-, QS-codes Q ≥ 0.03 in lead I 3-1 3-2 6-1 6-4-1 6-8 7-1-1

7-6 7-7 1-3-2 1-3-8, 7-3 All other codes except 8-2 All other codes All other codes 1-2-3, 1-2-7, 1-3-2, 1-3-6, 1-3-7, 1-3-8, all 2-, 3-, 4-, and 5-codes, 7-7, 7-8, 7-9, 7-10, 9-2, 9-4, 9-5, 9-7-1, 9-7-2 1-3-8, all 2-, 3-, 4-, and 5-codes, 9-2, 9-4, 9-5, 9-7-1, 9-7-2 1-3-8 All 2-, 3-, 4-, and 5-codes, 9-2, 9-4, 9-5 1-3-8, all 2-, 3-, 4-, and 5-codes, 9-2, 9-4, 9-5, 9-7-1, 9-7-2 8-2-4 8-1-1, 9-3 All other codes All other codes 8-1-2 8-1-1, 8-1-2 6-2-2, 8-1-1, 8-1-2 8-1-1, 8-1-2 6-2-2 6-5 All other codes except 7-4 or 6-2 6-5 8-1-1 All 2-codes

7-2-1 7-3 7-4 7-8 8-1-2 8-1-4 8-2-1 8-2-2 8-2-3 8-3-1 8-3-2 8-3-3 8-3-4 8-4-1 8-4-1 + heart rate ≥ 140 Heart rate > 100 8-4-2 9-1 1

1-3-8 was previously 1-2-8 New code from first edition 3 9-8-2 in the first edition was 9-8-1, and 9-8-4 was 9-8-2 in the first edition. 2

ECG Criteria for Significant Serial ECG Change See Chap. 15 for serial comparison rules Evolving Q-wave Q1. No Q-code in reference ECG followed by a record with a diagnostic Q-code (MC 1-1-1 through 1-2-7) OR an Equivocal Q-code (any MC 1-3-x) in reference ECG followed by record with any code 1-1-x Q-code. Q2. An Equivocal Q-code (any MC 1-3-x code) and no major ST-segment depression (MC 4-0, 4-4, 4-3) in reference ECG followed by a record with a diagnostic Qcode (MC 1-2-1 – 1-2-7) Plus a major ST-segment depression (MC 4-1-x or 4-2). 284

Q3.

Q4.

Q5. Q6. Q7.

An Equivocal Q-code (any MC 1-3-x) and no major T-wave inversion (MC 5-4, 5-3 or 5-0) in reference ECG followed by a record with a diagnostic Q-code (MC1-2-1 through 1-2-7) Plus a major T-wave inversion (MC 5-1 or 5-2). An Equivocal Q-code (any MC 1-3-x) and no ST-elevation in reference ECG followed by a record with a diagnostic Q-code (MC1-2-1 through 1-2-7) Plus an ST-segment elevation (MC 9-2). No Q-code and no MC 4-1-x or 4-2 in reference ECG followed by a record with an Equivocal Q- code (any MC 1-3-x) Plus MC 4-1-x or 4-2. No Q-code and no MC 5-1 or 5-2 in reference ECG followed by a record with an Equivocal Q- code (any MC 1-3-x) Plus a MC 5-1 or 5-2. No Q-code and no MC 9-2 in reference ECG followed by a record with an Equivocal Q-code (any MC 1-3-x) Plus a MC 9-2.

Evolving ST-Elevation STE-1 MC 9-0 in reference ECG followed by a record with MC 9-2 in at least 2 leads and >100% increase ST elevation in both leads. STE-2 MC 9-2 in reference ECG followed by a record with MC 9-2 in at least 2 leads and >100% increase in ST elevation in both leads. STE-3 MC 9-2 and no MC 5-1 or 5-2 in reference ECG followed by a record appearance of MC 5-1 or 5-2 with 100% increase in T wave inversion in at least 2 leads. STE-4 Reversal of evolving STE-1 (within the hospital ECG only). STE-5 Reversal of evolving STE-2 (within the hospital ECG only). Evolving ST-Depression / T Wave Inversion ST-T1 Either MC 4-0 (no 4-code), 4-4 or 4-3 in reference ECG followed by a record with MC 4-2 or 4-1-2 or 4-1-1 and > 100% increase in ST segment depression. ST-T2 Either MC 4-2 or 4-1-2 in reference ECG followed by a record with MC 4-1-1 and >100% increase in ST segment depression. ST-T3 Either MC 5-0, 5-4 or 5-3 in reference ECG followed by a record with MC 5-2 or 5-1 and > 100% increase in T-wave inversion. ST-T4 MC 5-2 in reference ECG followed by a record with MC 5-1 and >100% in T-wave inversion. ST-T5 MC 4-1-1 in reference ECG followed by a record with MC 4-1-1 and > 100% increase in ST depression. ST-T6 MC 5-1 in reference ECG followed by a record with MC 5-1 and >100% increase in T-wave inversion. ST-T7 MC 5-2 in reference ECG followed by a record with MC 5-2 and >100% increase in T-wave inversion. ST-T1R Reverse of ST-T14 ST-T2R Reverse of ST-T24 ST-T3R Reverse of ST-T34 ST-T4R Reverse of ST-T44 ST-T5R Reverse of ST-T54

285

ST-T6R ST-T7R

Reverse of ST-T64 Reverse of ST-T74

4

Requires >100% decrease in ST depression or T-wave inversion of follow-up record compared to reference ECG, and code changes must occur in the same lead groups.

Evolving Bundle Branch Block E-BBB1 No MC 7-1 in the reference ECG followed by an ECG with MC 7-1-1 in follow-up ECG and QRS duration increased by > 0.02 s. E-BBB2 No MC 7-2 in the reference ECG followed by an ECG with MC 7-2-1 in follow-up ECG and QRS duration increased by > 0.02 s. E-BBB3 No MC 7-4 in the reference ECG followed by an ECG with MC 7-4 in followup ECG and QRS duration increased by > 0.02 s. Evolving ECG – LVH 5 E-LVH 1 MC 3-0 in reference ECG followed by an ECG with a MC 3-1in the follow-up ECG, confirmed as a significant increase. E-LVH 2 MC 3-0 in reference ECG followed by an ECG with a MC 3-3 in the follow-up ECG, confirmed as a significant increase. E-LVH 3 MC 3-1 in reference ECG followed by an ECG with a MC 3-0 in the follow-up ECG, confirmed by a significant decrease. E-LVH 4 MC 3-3 in reference ECG followed by an ECG with a MC 3-0 in the follow-up ECG, confirmed by a significant decrease. E-LVH 5 MC 3-1 in the reference ECG followed by an ECG with a MC 3-1 in the follow-up ECG, confirmed by a significant increase or a significant decrease. E-LVH 6 MC 3-3 in the reference ECG followed by an ECG with a MC3-3 in the followup ECG, confirmed by a significant increase or significant decrease.

5

see page 232 for significant 3-code change

286

Appendix B The Novacode Criteria for Classification of ECG Abnormalities and Their Clinically Significant Progression and Regression The Novacode classification system is an extension of the Minnesota Code. It was developed initially in the late 1980s and further refined in 1998 and is still evolving.1,2 The Novacode ECG classification system provides a comprehensive hierarchical set of criteria for prevalent ECG abnormalities and for clinically significant serial ECG changes. The Structure of the Novacode -- Coding Categories for Prevalent ECG Abnormalities Baseline ECGs are commonly used to categorize a study population into groups based on major and minor abnormalities. The sequential coding categories of prevalent ECG abnormalities are summarized in Table B.1 (with corresponding Minnesota Codes). The first category of the coding system is applied to indicate conditions that suppress coding of some or all ECG abnormalities (code 0). The other categories are rhythms (code 1), atrioventricular conduction (code 2), complete bundle branch blocks (code 3), prolonged repolarization (code 4), myocardial infarction (MI) and ischemia (code 5), left ventricular hypertrophy (LVH) (code 6), left atrial enlargement (code 7), right ventricular hypertrophy (code 8), right atrial enlargement (code 9), and fascicular blocks (code 10). Detailed definitions for various ECG criteria used in the code for prevalent ECG abnormalities are listed below, which also contains definitions of the variables used to denote ECG measurements and waveform labels, as well as a table that provided a simple scheme for visual assessment of ECG record quality. Measurement The rules for basic ECG measurement and calculation as heart rate, durations and amplitudes for P-Q-R-S-T, intervals for P-R, Q-T, and QRS axis are same as the rules of the Minnesota Code in this manual, except the cut point for the codable Q wave (–75 µV for Novacode and –100 µV for Minnesota Code). TABLE B.1. Classification Code for Prevalent ECG Abnormalities (with Corresponding Minnesota Codes). Definition and Description

Novacode

Baseline ECG Suppression Codes

Novacode 0

ECG not available Inadequate quality or missing leads Inadequate quality Missing leads Lead connection interchange Uncorrectable lead connection interchanges (ECG uncodable)

287

NC-0.1 NC-0.2 NC-0.2.1 NC-0.2.2 NC-0.3 NC-0.3.1.x

Minnesota Code MC-9.8.2 MC-9.8.2 MC-9.8.2 MC-9.8.1

TABLE B.1. (continued) Definition and Description

Novacode

Minnesota Code

Correctable limb lead connection error (ECG codable) Correctable chest lead in V1-V3 connection error (ECG codable) Correctable chest lead in V4-V6 connection error (ECG codable) Correctable other chest lead connection error (ECG codable) QRS duration ≥ 120 ms

NC-0.3.2.x NC-0.3.3.x NC-0.3.4.x NC-0.3.5.x NC-0.4

Atrial fibrillation or atrial flutter Electronic pacemaker Other suppression codes Uncertain P wave detection

NC-0.5 NC-0.6 NC-0.7 NC-0.8

MC-9.8.3 MC-9.8.3 MC-9.8.3 MC-9.8.3 MC-7.1, MC-7.2, MC-7.4, MC-7.8, MC-6.4 MC-8.3.1, MC-8.3.2, MC-8.3.3 MC-6.8 MC-6.2, MC-6.1, MC-8.6

Rhythm Codes

Novacode 1

Basic sinus rhythm (SR) Normal sinus rhythm (NSR), rate from 51–94 cpm Sinus Bradycardia (SB) Sinus Tachycardia (ST) Supplementary codes to sinus rhythm With ectopic supraventricular complexes (ESVC) With aberrant supraventricular complexes (ASVC) With ectopic ventricular complexes (EVC) With pause (possible sinal arrest or sinoatrial block) Wandering atrial pacemaker (WAP) Junctional rhythm (JR) Junctional rhythm, rate from 45-64 cpm Junctional bradycardia (JB) Accelerated junctional rhythm (AJR) Ectopic atrial rhythm (EAR) Ectopic atrial rhythm, rate from 50–90 cpm Ectopic atrial bradycardia (EAB) Ectopic atrial tachycardia (EAT) Supraventricular tachycardia (SVT) Supraventricular tachycardia, rate < 130 cpm Supraventricular tachycardia, rate ≥ 130 cpm Atrial flutter or atrial fibrillation (AFLF) Atrial flutter type 1 (AFL1) Atrial flutter type 2 (AFL2) Atrial fibrillation (AF) Electronic pacemaker (PM) Ventricular pacemaker (VPM) or combination pacemaker (CPM) Atrial pacemaker only (APM) Ventricular Tachycardia (VT) Other abnormal rhythm codes Other Atrial Rhythms Other Ventricular Rhythms Indeterminate rhythm classification Inderminate Atrial Rhythms Indeterminate ventricular rhythm

AV Conduction Abnormalities

NC-1.0 NC-1.0.1 NC-1.0.2 NC-1.0.3 NC-1.0.S.1 NC-1.0.S.2 NC-1.0.S.3 NC-1.0.S.4 NC-1.1 NC-1.2 NC-1.2.1 NC-1.2.2 NC-1.2.3 NC-1.3 NC-1.3.1 NC-1.3.2 NC-1.3.3 NC-1.4 NC-1.4.1 NC-1.4.2 NC-1.5 NC-1.5.1 NC-1.5.2 NC-1.5.3 NC-1.6 NC-1.6.1 NC-1.6.2 NC-1.7 NC-1.8 NC-1.8.1 NC-1.8.2 NC-1.9 NC-1.9.1 NC-1.9.2

MC-8.8 MC-8.7 MC-8.1.1 MC-8.1.1 MC-8.1.2 MC-8.5.1 MC-8.1.4 MC-8.4.1 MC-8.4.1 MC-8.4.1 MC-8.4.1 MC-8.4.1 MC-8.4.1 MC-8.4.2 MC-8.4.2 MC-8.3.2 MC-8.3.2 MC-8.3.1 MC-6.8 MC-6.8 MC-8.2.3 MC-8.9 MC-8.2.x MC-8.9 MC-8.2.x

Novacode 2

First-degree AV block (AVB1) Second-degree AV block (AVB2) Second-degree AV block type Wenckebach or Mobitz 1 (AVB2W) Second-degree singular AV block or type Mobitz 2 (AVB2S) Second-degree multiple AV block (AVB2M) High-grade AV dissociation (AVD) Third-degree (complete) AV block (AVB3) AV dissociation with capture (AVDC) Ventricular preexcitation pattern (WPW)

NC-2.1 NC-2.2 NC-2.2.1 NC-2.2.2 NC-2.2.3 NC 2.3 NC-2.3.1 NC-2.3.2 NC-2.4

MC-6.3 MC-6.2.3 MC-6.2.2 MC-6.2.1 MC-6.1 MC-8.6.x MC-6.4 (continued)

288

TABLE B.1. (continued) Definition and Description

Novacode

Prolonged Ventricular Excitation

Novacode 3

Left bundle branch block (LBBB) LBBB without ECG evidence of myocardial infarction (MI) LBBB with possible MI Right bundle branch block (RBBB) RBBB without ECG evidence of MI RBBB with possible MI Indeterminate ventricular conduction delay (IVCD) IVCD without ECG evidence of MI IVCD with possible MI Borderline prolonged ventricular excitation Borderline delay of right ventricular excitation Borderline delay of left ventricular excitation

NC-3.1 NC-3.1.0 NC-3.1.1 NC-3.2 NC-3.2.0 NC-3.2.1 NC-3.3 NC-3.3.0 NC-3.3.1 NC-3.4 NC-3.4.1a NC-3.4.2

Minnesota Code

MC-7.1 MC-7.4 plus MC-1.x MC-7.2, MC-7.8 MC-7.2, 7.8 plus MC-1.x MC-7.4 MC-7.4 plus MC-1.x MC-7.3 MC-7.6

Novacode 4a

Prolonged Ventricular Repolarization Prolonged ventricular repolarization Marginal prolongation of ventricular repolarization Significant prolongation of ventricular repolarization

NC-4.1 NC-4.1.1 NC-4.1.2

ECG Categories Associated With Myocardial Infarction / Ischemia Q wave MI Q wave MI; major Q waves with or without ST-T abnormalities Q wave MI; moderate Q waves with ST-T abnormalities Possible Q wave MI; moderate Q waves without ST-T abnormalities Possible Q wave MI; minor Q waves with ST-T abnormalities Isolated ischemic abnormalities ST abnormalities without Q waves T wave abnormalities without Q waves Isolated minor Q and ST- T abnormalities Minor Q waves without ST - T abnormalities Minor ST-T abnormalities

Left Ventricular Hypertrophy

Novacode 5a

MC-1, MC-4, MC-5, MC-9.2

NC-5.1 NC-5.2

MC-1.1.x MC-1.2.x plus MC-4.1, 4.2, MC-5.1, 5.2 MC-1.2.x MC-1.3.x plus MC-4.1, 4.2, MC-5.1, 5.2

NC-5.3 NC-5.4

NC-5.5 NC-5.6

MC-4.1, 4.2 MC-5.1, 5.2

NC-5.7 NC-5.8

MC-1.3.x MC-4.3, 4.4, MC-5.3, 5.4

Novacode 6*

Left ventricular hypertrophy (LVH) Left ventricular hypertrophy without ST-T Left ventricular hypertrophy with ST-T

NC-6.1 NC-6.1.0 NC-6.1.1

MC-3.1 (if meet the Cornell Votage Criteria) MC-3.1 plus MC-5.1, 5.2, MC-4.1, 4.2 (if meet the Cornell Voltage Criteria)

Left Atrial Enlargement

Novacode 7

Left atrial enlargement (LAE)

NC-7.1

Right Ventricular Hypertrophy

Novacode 8

Right ventricular hypertrophy (RVH)

NC-8.1

Right Atrial Enlargement

MC-3.2

Novacode 9

Right Atrial Enlargement (RAE)

NC-9.1

Fascicular Blocks

MC-9.3

Novacode 10

Left anterior fascicular block (LAFB) Left posterior fascicular block (LPFB) a

MC-9.6

NC-10.1 NC-10.2

MC-7.7 MC-7.6

The criteria are different between Novacode and Minnesota Code NC-3.1 with QRS duration ≥ 125 ms (MC-7.1 with QRS duration ≥ 120 ms) NC-3.4.1 with QRS duration between 110 and 119 ms (MC-7.3 no QRS duration limit requirement) NC-3.4.2 with QRS duration between 110 and 119 ms (MC-7.6 with QRS duration between 100 and 119 ms) NC-4 (No MC code for prolonged ventricular repolarization) NC-5 (Novacode for MI/Ischemia–see Tables B. 2–5 below. MC combines the codes of MC 1, 4, 5, and 92 for MI/Ischemia see Chap. 4, 7, and 11) NC-6 (NC-LVH by Cornell Voltage Criteria; MC-LVH by Sokolow-Lyon Voltage Criteria)

289

Dictionary of Variables and Novacode Definitions of ECG Wavesa Amplitudes are in microvolts and durations in milliseconds (µV after variable name implies the amplitude and ms the duration of the wave; if not clear from the context, subscript a is used to indicate amplitude and d to indicate duration). The amplitudes of P, PP (P prime), J, ST, T, and T prime are positive or negative (signed); the amplitudes of other waves (QRS) are absolute values. Definitions of ECG Waveform Variables HR J JT JTI P P2 PR Q QRS QRSn QRSp QS QT QTI R Ri RPT R2 R/Q R/S S2 STD STE T Tn TP a

Heart (ventricular) rate, complexes per min (CPM) j point (QRS offset); used to define time point reference for ST-segment measurements and time point for amplitude measurement for ST-segment elevation QTd – QRSd JT prolongation index (%) = (JT/518)*(Heart Rate + 100) Initial P wave exceeding 25 µV (absolute value) Secondary P (prime) deflection (with opposite polarity of P) exceeding 25 µV (absolute value) P-R interval Initial deflection within QRS complex ≤ –75 µV and ≥ 20 ms followed by a positive deflection (R) ≥100 µV QRS interval Net QRS deflection (maximum positive – absolute value of maximum negative QRS deflection) Peak-to-peak amplitude (µV) of QRS (maximum positive + absolute value of maximum negative amplitude) Initial deflection within QRS ≤ –75 µV, with no positive deflection ≥ 100 µV QT interval QT prolongation index (%) = (QT/656)*(Heart Rate + 100) First positive deflection within QRS (in Q score, used to flag the presence of Ri) Initial R within QRS with ≥ 25 µV and no Q wave preceding (Qa ≤ 50 µV) R peak time (ms), from QRS onset to R maximum Secondary R (prime) wave, a positive deflection ≥ 100 µV within QRS complex following an S wave Ra/Qa ratio Ra/Sa ratio Secondary S (prime) wave, a negative deflection ≥ 100 µV within ORS complex following an RP wave ST depression amplitude at J + 60 ms ST elevation amplitude at J point if > 0 First deflection within T wave, positive or negative Net T deflection (maximum positive – absolute value of maximum negative T deflection) T prime deflection, positive or negative, with opposite polarity of T

Dictionary reproduced from reference 2 with permission of ELSEVIER publishing company. 290

Tp TQ X Z

Peak-to-peak amplitude (µV) of T wave (maximum positive + absolute value of maximum negative amplitude) Interval from end of T to beginning of QRS complex Flag used to denote in Q score assignment initial R with amplitude of 100 –199 µV Flag for QRS waveform pattern with no codable Q or QS wave and initial R ≥ 200 µV (no flag E or X)

General Definitions Related to Rhythm Codes Aberrant Coalescent cpm Ectosinal (ES) Junctional Nodal Sinal Sinal P Sinal QRS

QRS complex (generally ectosinal premature) with blocked conduction in some branch of the conduction system QRS complex overlapping ST-T of the preceding QRS-T complex (“R-on-T”) cycles per minute, referring to ventricular rate, atrial rate, or the rate of flutter waves Ectopic supraventricular excitation originating from outside the sinus node Atrial and/or ventricular complex or rhythm originating from atrioventricular (AV) junction Atrioventricular nodal or atrioventricular junctional complex or rhythm Originating at SA node P wave with normal P axis (PII ≥ 0 µV and P aVR ≤ 0 µV) QRS complex coupled with a sinal P wave

Codes for Prevalent ECG Abnormalities 0. Baseline EGG Suppression Codes

Note: Character “-” or “.” on the coding or report form indicates codes suppressed. 0.1 ECG not available 0.2 Inadequate quality or missing leads 0.2.1 Inadequate quality Criteria C1: Quality grade 5 C2: ECG hard copy contrast inadequate Code 0.2 = C1 or C2 Note: C1 = poor quality and is present if either there is a baseline drift > 4 mm (choose three successive P-QRS-T complexes and measure peakto-peak baseline drift in millimeters in the worst lead); OR > 2 mm perturbation of the isoelectric line (measurement in millimeters from the highest peak-to-peak random [muscle] or 60-Hz noise in the worst lead). 0.2.2 Missing leads 0.3 Lead connection interchange 0.3.1 RA/RL interchange (ECG uncodable) Criteria C1: PII < 50 µV, QRSplI < 50 µV and TpII < 50 µV C2: I = -III (P, ORS, and T are mirror images of each other) Code 0.3 = C1 and C2 291

0.4 0.5

0.6

0.7

0.8 0.0

0.3.2 Other lead connection interchanges (correction made and ECG coded) 0.3.3 Correctable chest lead in V1-V3 connection error (ECG codable) 0.3.4 Correctable chest lead in V4-V6 connection error (ECG codable) 0.3.5 Correctable other chest lead connection error (ECG codable) Any conditions with ORS duration ≥ 120 ms (codes 2.4, 3.1, 3.2, 4.3, and 1.9) Note: Code 0.4 suppresses ST-T scores. Atrial fibrillation or flutter Criteria C1: Rhythm codes 1.5.1 or 1.5.2 (atrial flutter type 1 or type 2) or 1.5.3 (atrial fibrillation) present Code 0.5 = C1 Note: Code 0.5 suppresses code 2, code 7, and code 9. Atrial flutter suppresses ST-T scores and the corresponding prevalent and incident ischemic codes. Ventricular or dual-chamber electronic pacemaker Note 1: Except demand pacemaker with more than two adequate-quality nonpaced complexes is available for coding from all lead groups. Note 2: Code 0.6 suppresses all codes (except code 1.6.2). Other suppression codes Note: Includes atrial electronic pacemaker, which suppresses code 3, code 7, and code 9. Uncertain P wave detection No suppression codes

1. Rhythm Codes 1.0 Basic sinus rhythm (SR) Criteria C1: PII ≥ 0 µV and PaVR ≤ 0 µV C2: P amplitude variation < 100 µV C3: Presence of three or more P-QRS-T complexes meeting criteria C1 and C2 Code 1.0 = C1 and C2 and C3 Note 1: C1 implies P axis ≤ 120° and ≥ -30°. Note 2: Usually sinus rhythm is associated with fixed coupling between the normal P waves and the following QRS complexes, with P-R interval variation < 20% from the median PR. However, in Mobitz type 1 first degree AV block (code 2.2.1), the PR interval varies. 1.0.1 Normal sinus rhythm (NSR) Criteria C1: Basic rhythm sinus (code 1.0) C2: Ventricular rate 51-94 cpm Code 1.0.1 = C1 and C2 1.0.2 Sinus bradycardia (SB) Criteria C1: Basic rhythm sinus (code 1.0) C2: Ventricular rate ≤ 50 cpm Code 1.0.2 = C1 and C2 292

1.0.3 Sinus tachycardia (ST) Criteria C1: Basic rhythm sinus (code 1.0) C2: Ventricular rate ≥ 95 cpm Code 1.0.3 = C1 and C2 1.1 Wandering atrial pacemaker (WAP) Criteria C1: Presence of more than one P wave trains with three or more P waves in each and with P amplitudes changing by 100 µV or more Code 1.1 = C1 Note: Sinus rhythm with segments of transient ectopic atrial or junctional rhythm (defined below) is coded as WAP 1.2 Junctional rhythm (JR) Criteria C1: PaVR > 0 µV and PI ≥ 0 µV C2: PR≤ 120 ms and PR variation < 20 ms C3: Retrograde P waves C4: No P waves identifiable and no atrial flutter or fibrillation waves C5: R-Rmax - R-R min ≤ 40 ms Code 1.2 = (C1 and C2) or ([C3 or C4] and C5) Note 1: Criterion C1 implies a P axis from -60° to -90°. Note 2: C1 with PR > 120 ms (possible coronary sinus rhythm or JR with delayed antegrade conduction) is coded under code 1.3 (EAR). Note 3: For C5, exclude possible competing ectopic or sinus complexes. Note 4: Atrial fibrillation with junctional rhythm is coded under code 1.5.3 (atrial fibrillation). 1.2.1 Junctional rhythm, rate 45-64 cpm Criteria C1: Code 1.2 C2: Ventricular rate 45-64 cpm Code 1.2.1 = C1 and C2 1.2.2 Junctional bradycardia (JBR) Criteria C1: Code 1.2 C2: Ventricular rate < 45 cpm Code 1.2.2 = C1 and C2 1.2.3 Accelerated junctional rhythm (AJR) Criteria C1: Code 1.2 C2: Ventricular rate from 65 cpm and < 89 cpm Code 1.2.3 = C1 and C2 Note: Code as narrow QRS tachycardia (code 1.4) if rate ≥ 90 cpm. 1.3 Ectopic atrial rhythm (EAR) Criteria C1: PII < 0 µV 293

C2: PaVR > 0 µV C3: No code 1.2 (JR) Code 1.3 = (C1 or C2) and C3 Note: Criterion C1 or C2 implies a P axis < -30° or > 120° . 1.3.1 Ectopic atrial rhythm, rate 50-90 cpm Criteria C1: Code 1.3 C2: Ventricular rate 50-89 cpm Code 1.3.1 = C1 and C2 1.3.2 Ectopic atrial bradycardia (EABR) Criteria C1: Code 1.3 C2: Ventricular rate < 50 cpm Code 1.3.2 = C1 and C2 1.3.3 Ectopic atrial tachycardia (EAT) Criteria C1: Code 1.3 C2: Ventricular rate ≥ 90 cpm Code 1.3.3 = C1 and C2 1.4 Supraventricular (SVT) or narrow QRS tachycardia Criteria C1: Six or more successive supraventricular ectopic complexes, with QRS < 120 ms C2: Ventricular rate ≥ 95 cpm Code 1.4 = C1 and C2 Note: If fewer than six ectopic complexes, include them in supraventricular ectopic complex count. 1.4.1 Supraventricular tachycardia, rate < 130 cpm Criteria C1: Code 1.4 C2: Ventricular rate during episode < 130 cpm Code 1.4.1 = C1 and C2 1.4.2 Supraventricular tachycardia, rate ≥ 130 cpm Criteria C1: Code 1.4 C2: Ventricular rate during episode ≥ 130 cpm Code 1.4.2 = C1 and C2 1.5 Atrial flutter or fibrillation (AFLF) Screening criteria C1: No P waves present C2: Flutter (F) waves ≥ 100 µV peak to peak with repetitive, regular morphology, present in lead II, aVF or V1 C3: Fibrillation (f) waves or F waves with irregular cycle intervals or amplitudes, in II, III, or aVF C4: R-R intervals irregular (fewer than three R-R within 40-ms class interval) Code 1.5 = C1 and (C2 or C3 or C4 or C5) 294

1.5.1 Atrial flutter type 1 (AFL1) Criteria C1: Five or more R-R intervals, each with F wave amplitudes ≥ 100 µV peak to peak C2: F ≤ 333 cpm (F cycle interval ≥ 180 ms) (i.e., ≥ 4.5 mm at 25 mm/second) C3: At least partial regularity of R-R intervals, with three or more R-R intervals within 40 ms of each other (i.e., within two adjacent class intervals of 20 ms); if ventricular rate ≥ 100 cpm, four or fewer R-R intervals are required to be within 40 ms of each other Code 1.5.1 = C1 and C2 and C3 1.5.1.1 Classic atrial flutter type 1 (AFL1C) Criteria C1: Code 1.5.1 C2: F waves predominant in lead II or aVF, sawtooth pattern, with the initial leading edge notch of the F wave negative with respect to ECG baseline (onset of QRS) Code 1.5.1.1 = C1 and C2 1.5.1.2 Variant atrial flutter type 1 (AFL1V) Criteria C1: Code 1.5.1 C2: F waves predominant in lead II or aVF sawtooth pattern, with the initial leading edge notch of the F wave positive with respect to ECG baseline Code 1.5.1.2 = C1 and C2 Note 1: Possible atrial flutter with 1:1 AV conduction is coded under code 1.4 (supraventricular tachycardia). Note 2: Supplementary codes for dominant and variable AV conduction with atrial flutter are defined under codes 1.5.1 S 9 and 1.5.1 S 11. 1.5.2 Atrial flutter type 2 (AFL2) Criteria C1: F waves ≥ 100 µV peak to peak sustained for 5 or more R-R intervals C2: F > 333 cpm and < 430 cpm (F cycle interval 141–179 ms, i.e., 3.6-4.4 mm at 25 mm/second Code 1.5.2 = C1 and C2 Note: In type 2 atrial flutter at F > 350 cpm, F wave morphology tends to become irregular in amplitude and in cycle length, and ventricular rate often does not meet the partial regularity criteria characteristics of atrial flutter type 1. 1.5.3 Atrial fibrillation (AF) Criteria C1: Code 1.5 C2: Criteria for codes 1.5.1 and 1.5.2 not met Code 1.5.3 = C1 and C2 Note: Supplementary code for atrial fibrillation with probable junctional rhythm is defined under code 1.5.3 S 12 - 1.5.3 S 14. 295

1.6

1.7

1.8

1.9

1.5.4 Atrial fibrillation/flutter with possible dominant AV conduction Criteria C1: Fibrillation waves or four or less R-R intervals, each with F waves ≥ 100 µV peak to peak C2: Possible dominant AV conduction present, with R-R within two adjacent class intervals of 20 ms (i.e., within 40 ms from each other). If mean R-R ≤ 600 ms, four or more R-R intervals within 40 ms required to define possible dominant conduction. Code 1.5.4 = C1 and C2 Electronic pacemaker (PM) 1.6.1 Ventricular pacemaker (VPM) or combination (dual chamber) pacemaker (CPM) Criteria C1: Coupled pacemaker spikes with spike–spike interval ≥ 80 ms C2: Single pacemaker spikes C3: QRS ≥ 120 ms Code 1.6.1 = (C1 and C3) or (C2 and C3) 1.6.2 Atrial electronic pacemaker (APM) Criteria C1: Single pacemaker spikes >80 ms before QRS complex, preceding P waves C2: QRS < 120 ms Code 1.6.2 = C1 and C2 Ventricular tachycardia (VT) Criteria C1: Three or more successive ventricular ectopic complexes with rate ≥ 130 cpm Code 1.7 = C1 Note: Other ventricular ectopic complexes counted separately (under continuous measurements and counts). Other abnormal rhythm classification 1.8.1 Other atrial rhythms 1.8.2 Other ventricular rhythms Indeterminate rhythm classification 1.9.1 Indeterminate atrial rhythm 1.9.2 Indeterminate ventricular rhythm (IVR)

2. Atrioventricular Conduction Abnormalities 2.0 AV conduction normal Criteria C1: PR interval 120-219 ms C2: PR intervals within 40-ms class interval (excluding ectopic complexes) Code 2.0 = C1 and C2 2.1 First-degree AV block (AVB1) Criteria C1: PR ≥ 220 ms 296

C2: P-R intervals within 40-ms class interval (excluding ectopic complexes) Code 2.1 = C1 and C2 2.2 Second-degree AV block (AVB2) Criteria C1: Occurrence of one or more blocked P waves within the R-R interval of conducted P waves Code 2.2 = C1 2.2.1 Second-degree AV block type Wenckebach or Mobitz 1 (AVB2W) Criteria C1: Repetitive cycles of progressive prolongation of PR followed by a blocked P wave Code 2.2.1 = C1 2.2.2 Second-degree singular AV block or type Mobitz 2 (AVB2S) Criteria C1: Singular blocked P at variable or fixed (1:2, 1:3, etc.) block ratio Code 2.2.2 = C1 Note 1: Singular blocked P wave equal to no more than one blocked P wave within any R-R interval. Blocked P is in a “regular” P wave train (rather than an early premature P within the refractory period of AV node). Note 2: Block ratio for the second degree singular AV block is the ratio of blocked P waves to conducted P waves. Block ratio = 1:x, where x is the number of conducted P waves following the blocked P wave. Second-degree singular AV block with 1:1 block ratio is often confusingly called 2:1 AV block, and with a 1:2 block ratio, it is called 3:1 AV block. Note 3: Second-degree singular AV block with 1:1 block ratio may be a Wenckebach block that is revealed only if the block ratio changes to 1:2 or 1:3. A true Mobitz 2 second-degree AV block is commonly associated with a complete bundle branch block or with bifascicular block. 2.2.3 Second-degree multiple AV block (AVB2M) Criteria C1: Two or more blocked P waves within R-R interval of conducted atrial complexes Code 2.2.3 = C1 2.3 High-grade AV dissociation (AVD) Criteria C1: P wave train and QRS wave train independent (with no consistent relationship) for the majority of the complexes C2: R-R intervals of the independent QRS complexes regular within 100 ms, with QRS duration varying less than 10 ms Code 2.3 = C1 and C2 Note 1: Second-degree AV blocks can also be considered to present a form of AV dissociation. Note 2: AV dissociation with atrial flutter is coded under Code 1.5.1 S 10. 297

2.3.1 Third-degree (complete) AV block (AVB3) Criteria C1: Criteria for code 2.3 persist throughout the record Code 2.3.1 = C1 Note 1: Ventricular rate is usually slower than atrial rate. Note 2: If several types of AV blocks coexist in the same record, code the highest block. 2.3.2 AV dissociation with captured ventricular or atrial complexes (AVDC) Criteria C1: Code 2.3 C2: Occurrence of a P wave followed by a QRS complex with preceding R-R interval ≥ 100 ms shorter than R-R intervals meeting the regularity criteria C3: Occurrence of a retrograde P wave with preceding P-P interval ≥ 100 ms shorter than those in the regular P wave train Code 2.3.2 = C1 and (C2 or C3) 2.4 Ventricular preexcitation pattern Wolff-Parkinson-White syndrome (WPW) Criteria C1: PR < 120 ms C2: P axis from 1° to 90° C3: QRS complex ≥ 120 ms C4: Delta wave present Code 2.4 = C1 and C2 and C3 and C4 Subclassiflcation of Preexcitation Patterns Criteria C1: Delta wave positive in lead I C2: Delta wave positive in lead V1 C3: Delta wave negative in lead V1 C4: Delta wave isoelectric in lead V1 C5: Q or QS waves in leads I and V6 C6: Q or QS waves in leads II and aVF C7: QRS mainly positive in lead III C8: QRS mainly negative in lead III C9: QRS mainly positive in lead V1 C10: QRS mainly negative in lead V1 C11: Delta wave positive in leads II and aVF and positive or isoelectric in lead III C12: Delta wave negative in leads II, III, and aVF C13: Delta wave positive in leads V2, V3, V4, V5 and V6 C14: Delta wave negative or isoelectric in lead V6 C15: Ri < 100 µV and S ≥ 100 µV in lead V1 C16: Ri ≥ 100 µV and S ≤ 100 µV in lead V2 Code 2.4.1 Anterior right ventricular preexcitation = C1 and C4 and C8 and C10 Code 2.4.2 Posterior right ventricular preexcitation = C3 and C6 and C10 Code 2.4.3 Posterior left ventricular preexcitation =C1 and C2 and C6 and C8 and C9 and C14 298

Code 2.4.4 Lateral left ventricular preexcitation = C2 and C5 and C7 and C14 Code 2.4.5 Anterior paraseptal preexcitation = C1 and C4 and C11 Code 2.4.6 Posterior paraseptal preexcitation = C1 and C12 and C13 and C15 and C16 2.5 Other AV conduction abnormalities (concealed conduction, AV dissociation other than third-degree AV block, etc.) 3. Prolonged Ventricular Excitation 3.0 QRS duration normal Criteria C1: QRS < 110 ms Code 3.0 = C1 3.1 Left bundle branch block (LBBB) Criteria C1: QRS ≥ 125 ms C2: WPW absent (no code 2.4) C3: R peak time or R2 peak time ≥ 60 ms in leads V5 or V6 or I or aVL Code 3.1 = C1 and C2 and C3 3.1.0 LBBB without ECG evidence of myocardial infarction (MI) Criteria C1: Code 3.1 C2: Q score < 25 Code 3.1.0 = C1 and C2 3.1.1 LBBB with possible MI Criteria C1: Code 3.1 C2: Q score ≥ 25 Code 3.1.1 = C1 and C2 3.2 Right bundle branch block (RBBB) Criteria C1: QRS ≥ 120 ms C2: WPW absent (no code 2.4) C3: R peak time or R2 peak time ≥ 60 ms in leads V1 or V2 C4: S duration ≥ R duration in I or V6 Code 3.2 = (C1 and C2 and C3) or (C1 and C2 and C4) 3.2.0 RBBB without ECG evidence of MI Criteria C1: Code 3.2 C2: Q score < 25 Code 3.2.0 = C1 and C2 3.2.1 RBBB with possible MI Criteria C1: Code 3.2 C2: Q score ≥ 25 Code 3.2.1 = C1 and C2

299

3.3 Indeterminate ventricular conduction delay (IVCD) Criteria C1: QRS ≥ 120 ms C2: WPW absent (no code 2.4) C3: No code 3.1 or 3.2 Code 3.3 = C1 and C2 and C3 Note: Code 3.3 includes LBBB pattern with QRS 120–124 ms. 3.3.0 IVCD without ECG evidence of MI Criteria C1: Code 3.3 C2: Q score < 25 Code 3.3.0 = C1 and C2 3.3.1 IVCD with possible MI Criteria C1: Code 3.3 C2: Q score ≥ 25 Code 3.3.1 = C1 and C2 3.4 Borderline prolonged ventricular excitation Criteria C1: QRS 110–119 ms Code 3.4 = C1 3.4.1 Borderline delay of right ventricular excitation Criteria C1: Code 3.4 C2: R2 in V1 Code 3.4.1 = C1 and C2 3.4.2 Borderline delay of left ventricular excitation Criteria C1: Code 3.4 C2: No code 3.4.1 Code 3.4.2 = C1 and C2 4. Prolonged Ventricular Repolarization 4.0 No prolonged ventricular repolarization Criteria C1: QTI < 112% Code 4.0 = C1 4.1 Prolonged ventricular repolarization Criteria C1: QTI ≥ 112% Code 4.1 = C1 4.1.1 Marginal prolongation of ventricular repolarization Criteria C1: QTI 112% to 116% Code 4.1.1 = C1 300

4.1.2* Definite prolongation of ventricular repolarization Criteria C1: QTI > 116% Code 4.1.2 = C1 Note 1: QTI (%) = (QT/656) × (HR + 100). QT is in ms. At heart rate 60 cpm, QTI 112% corresponds to a QT of 460 ms. Note 2: It is essential to use JTI rather than QTI for coding prolonged repolarization if QRS ≥ 120 ms. JT prolongation index JTI (%) = (JT/518) × (HR + 100) where JT = QT – QRS. Note 3: It should be recognized that QTI includes not only the period of ventricular repolarization but also ventricular excitation. The inclusion of separate terms for ventricular repolarization (JT) and excitation (QRS) may be warranted. 5. ECG Categories Associated with Prevalent Myocardial Infarction/Ischemia (MI Likelihood) 5.0 No significant Q waves and no significant STT abnormalities Criteria C1: No codes 5.1 through 5.8 Code 5.0 = C1 High Likelihood of Q Wave MI 5.1 Q wave MI with major Q waves Criteria C1: Q score ≥ 35 in any lead group Code 5.1 = C1 5.2 Q wave MI with moderate Q waves and with ST-T abnormalities Criteria C1: Q score ≥ 25 in any lead group C2: ST-segment depression (STD) or T wave negativity (TN) score 20 or higher in any lead group Code 5.2 = C1 and C2 Moderate Likelihood of MI 5.3 Possible Q wave MI with moderate Q waves and without ST-T abnormalities Criteria C1: Q score ≥ 25 in any lead C2: STD and TN score < 20 in all lead groups Code 5.3 = C1 and C2 5.4 Possible Q wave MI with minor Q waves and with ST-T abnormalities Criteria C1: Q score ≥ 15 in any lead C2: STD or TN score ≥ 20 in any lead group Code 5.4 = C1 and C2 Isolated Ischemic Abnormalities 5.5 ST abnormalities without Q waves Criteria C1: STD score ≥ 20 in any lead group 301

C2: Q score < 15 in all leads Code 5.5 = C1 and C2 5.6 T wave abnormalities without Q waves Criteria C1: TN score ≥ 20 in any lead group C2: Q score < 15 in all leads Code 5.6 = C1 and C2 Minor Q Wave or ST- T Abnormalities 5.7 Minor Q waves without ST-T abnormalities Criteria C1: Q score ≥ 15 in any lead C2: STD and TN score < 20 in all lead groups Code 5.7 = C1 and C2 5.8 Minor ST-T abnormalities Criteria C1: STD or TN score ≥ 10 in any lead group Code 5.8 = C1 Note 1: Code 0.1 (ECG not available) and codes 0.2.1 and 0.2.3 (inadequate quality or missing leads, including RA/RL reversal) interfere with morphologic codes 0.3 (ventricular pacemaker), 0.4 (complete bundle branch block and Wolff-Parkinson-White pattern), 0.6 (electronic pacemaker) and suppress all code 5 items. Note 2: Code 6.0 (no left ventricular hypertrophy) is recommended as an additional condition for codes 5.5 and 5.6. 6. Left Ventricular Hypertrophy 6.0 No ventricular hypertrophy Criteria C1: Code 6.1 not present Code 6.0 = C1 6.1 Left ventricular hypertrophy (LVH) Criteria C1: RaVL + SV3 ≥ 2,800 µV in men C2: RaVL + SV3 ≥ 2,200 µV in women Code 6.1 = C1 or C2 6.1.0 LVH without ST-T abnormalities Criteria C1: Code 6.1 C2: STD or TN score < 20 Code 6.1.0 = C1 and C2 6.1.1 LVH with ST-T abnormalities Criteria C1: Code 6.1 C2: STD or TN score ≥ 20 Code 6.1.1 = C1 and C2 302

7. Left Atrial Enlargement 7.0 No left atrial enlargement Criteria C1: Code 7.1 not present Code 7.0 = C1 7.1 Left atrial enlargement Criteria C1: PII ≥ 120 ms C2: P2V1 ≤ -100 µV, or (PV1 ≤ -100 µV if P2V1 = 0) C3: (P2aV1 x P2dV1) < -4000 µVms Code 7.1 = C1 or C2 or C3 Note: Use C3 alone, if available, for higher specificity. 8. Right Ventricular Hypertrophy 8.0 No right ventricular hypertrophy Criteria C1: Code 8.1 not present and QRSd < 120 ms Code 8.0 = C1 8.1 Right ventricular hypertrophy (RVH) Criteria C 1: QRSnaVR ≥ 0 µV and QRSnaVL ≤ 0 µV C2: (R/S) I ≤ 1 and (R/S) II ≤ 1 and (R/S) III ≤1 C3: (R/S) V5 ≤ 1 C4: (R/S) V6 ≤ 1 Code 8.1 = (C1 or C2) and (C3 or C4) Note: Criterion 1 (net QRS amplitude in aVR ≥ 0 µV and in aVL ≤ 0 µV) implies QRS axis from 120° to 240° (right axis deviation). 9. Right Atrial Enlargement 9.0 No right atrial enlargement Criteria C1: Code 9.1 not present Code 9.0 = C1 9.1 Right atrial enlargement Criteria C1: PII > 250 µV Code 9.1 = C1 10. Fascicular Blocks 10.0 No fascicular block Criteria C1: QRS axis > –45° C2: QRS axis ≤ 90° Code 10.0 = C1 and C2

303

10.1 Left anterior fascicular block (LAFB) Criteria C1: QRS < 120 ms C2: QRSII < 0 µV and QRSIII < 0 µV C3: RiS patterns in lead II, with initial Ra < 200 µV C4: Q 25-100 µV in lead aVL C5: R ≥ 200 µV and R peak time ≥ 40 ms in lead aVL Code 10.1 = C1 and C2 and C3 and C4 and C5 Note: Criterion 2 (net QRS amplitude < 0 µV in leads II and III) implies QRS axis from -31° to -119°. 10.2 Left posterior fascicular block (LPFB) Criteria C1: QRS < 120 ms C2: QRSI < 0 µV and QRSaVF > 0 µV C3: Code 8.0 (no RVH) C4: Q from 25 µV to 99 µV and R ≥ 100 µV in III and aVF C5: Q < 40 ms in III and aVF Code 10.2 = C1 and C2 and C3 and C4 and C5 Note: Criterion C2 implies QRS axis from 91° to 179° . 11. Other Clinically Significant Abnormalities Note: Code 11 is reserved for other abnormalities not included in codes 1 through 10 and not specified in this context Definitions of Supplementary Codes (S) Note: The first two digits (preceding S) identify the associated main rhythm code (i.e. 1.0 S = supplementary condition to sinus rhythm, code 1.0). Supplementary Codes to Sinus Rhythm 1.0 S 1 With ectopic (ectosinal) supraventricular complexes (ESVC) Criteria C1: Code 1.0.1 or code 1.0.2 (NSR or SB) C2: QRS morphology matches sinal QRS complexes (QRS duration within 20 ms and QRS wave labeling same as for sinal QRS) C3: P amplitude differs by more than 100 µV from sinal P waves, or retrograde P or no P wave discernible C4: PR ≥ 40 ms shorter than PR of sinal QRS complexes C5: R-R of the early complex 200 ms shorter than the preceding R-R and ≥ 240 ms shorter than the R-R following the ectopic complex Code 1.0 S 1 = (C1 and C2) and (C3 or C4 or C5) Note: C5 reflects the minimum expected combined effect of the ectopic complex on the prematurely (R-R preceding) and SA node suppression (R-R following). 1.0 S 1.1 With atrial bigeminy (ABG) Criteria C1: Code 1.0 S.1 304

C2: Ectopic complex follows every sinal QRS complex Code 1.0 S 1.1 = C1 and C2 1.0 S 1.2 With atrial trigeminy (ATG) Criteria C1: Code 1.0 S.1 C2: Ectopic complex after every pair of sinal QRS complexes Code 1.0 S 1.2 = C1 and C2 1.0 S 2 With aberrant supraventricular complexes (ASVC) Criteria C1: Code 1.0.1 or code 1.0.2 (NSR or SB) C2: QRS ≥ 20 ms longer than normally conducted sinal QRS C3: P wave precedes wide QRS complex C4: RSR2 in V1, with R2 > R C5: QRSd ≤ 140 ms Code 1.0 S 2 = C1 and C2 and [C3 or (C4 and C5)] or (C5 and (C6 or C7))] 1.0 S 3 With ectopic ventricular complexes (EVC) Criteria C1: QRS ≥ 120 ms or QRS ≥ 20 ms longer than normally conducted QRS complexes. C2: Criteria for code 1.0 S.2 not met Code 1.0 S 3 = C1 and C2 Note 1: Code 1.0 S.2 includes interpolated ectopic ventricular complexes Note 2: QRS fusion complexes (preceding sinal P occurring with normal timing in the P wave train) are counted as ectopic ventricular complexes. 1.0 S 3.1 With a doublet of ectopic ventricular complexes (DEVC) Criteria C1: Code 1.0 S.3 C2: Two EVCs in succession within one R-R interval of sinal QRS complexes Code 1.0 S 3.1 = C1 and C2 Note: A triplet of EVCs is coded under code 1.9 (VT). 1.0 S 3.2 With coalescent ventricular ectopic complexes (CEVC) Criteria C1: Ectopic ventricular complex overlaps the ST-T of the preceding QRS-T complex Code 1.0 S 3.2 = C1 1.0 S 3.3 With polymorphic ectopic ventricular complexes (PEVC) Criteria C1: QRSa (net QRS amplitudes) of EVCs differ by ≥ 50% C2: QRS durations of EVCs differ by ≥ 20 ms Code 1.0 S 3.3 = C1 and C2 1.0 S 3.4 With ventricular bigeminy (VBG) Criteria C1: Code 1.0 S.3 C2: Ectopic complex follows every sinal QRS complex Code 1.0 S 3.4 = C1 and C2 305

1.0 S 3.5 With ventricular trigeminy (VTG) Criteria C1: Code 1.0 S.3 C2: Ectopic complex after every pair of sinal QRS complexes Code 1.0 S 3.5 = C1 and C2 1.0 S 4 With pause (possible sinoatrial arrest or block) Criteria C1: Code 1.0 C2: P-P interval containing pause prolonged ≥ 90% compared with median P-P of sinal P waves C3: No P wave in the prolonged P-P interval until the next PQRS complex C4: Preceding PQRS complex not an ectopic supraventricular or ventricular complex Code 1.0 S 4 = C1 and C2 and C3 and C4 1.0 S 5 With reduced heart rate variability (HRV) Criteria C1: Code 1.0.1 (normal sinus rhythm) C2: R-R interval variation range of normally conducted QRS complexes < 40 ms, excluding complexes following ectopic (ventricular or supraventricular) complexes (interpolated or with compensatory pause) Code 1.0 S 5 = C1 and C2 Note: With computer measurements of all R-R intervals of normally conducted QRS complexes (N-N intervals) available, code 1.0 S.5 = SDNN ≤ 5 ms, where SDNN is the standard deviation of N-N intervals. 1.0 S 6 With increased heart rate variability Criteria C1: Code 1.0.1 (normal sinus rhythm) C2: Largest successive difference of R-R intervals of normally conducted QRS complexes > 100 ms excluding complexes following ectopic (ventricular or supraventricular) complexes (interpolated or with compensatory pause) Code 1.0 S 6 = C1 and C2 Note: With computer measurements of all R-R intervals of normally conducted QRS complexes (N-N intervals) available, 1.0 S.6 = SDNN ≥ 30 ms, where SDNN is the standard deviation of N-N intervals. Supplementary Codes to Ectopic Atrial Rhythm 1.3 S 7 Probably left atrial ectopic focus Criteria C1: Code 1.3 C2: PI < 0 C3: PV1 > 0 and PPV1 ≥ 0 Code 1.3 S 7 = C1 and C2 and C3 Note: C3 implies that PV1 is positive of bifid.

306

1.3 S 8 Probably right atrial ectopic focus Criteria C1: Code 1.3 C2: No code 1.3 S 7 Code 1.3 S 8 = C1 and C2 Supplementary Codes to Atrial Flutter 1.5.1 S 9 With dominant AV conduction ratio 1 to x (specify x) Criteria C1: Conduction ratio (x) is constant for the majority of R-R intervals Code 1.5.1 S 9 = C1 Note 1: In AV conduction ratio, x = (1 + N), where N is the number of nonconducted F waves following a conducted F wave (x is also the ratio of the dominant regular R-R interval to the F cycle length). 1.5.1 S 10 With AV dissociation Criteria C1: The majority of R-R intervals are constant within 40 ms C2: FR intervals are irregular (except for possible captured ventricular complexes) C3: Dominant R-R is not a multiple of the F cycle length within 40 ms Code 1.5.1 S 10 = C1 and C2 and C3 1.5.1 S 11 With variable AV conduction Criteria C1: No code 1.5.1 S 10 C2: Conduction ratio varies Code 1.5.1 S 11 = C1 and C2 Supplementary Codes to Atrial Fibrillation 1.5.3 S 12 With AV dissociation and junctional rhythm Criteria C1: Code 1.5.3 C2: R-R interval variation range < 40 ms Code 1.5.3 S 12 = C1 and C2 1.5.3 S 13 With slow ventricular response Criteria C1: Code 1.5.3 C2: Ventricular rate < 50 cpm Code 1.5.3 S 13 = C1 and C2 1.5.3 S 14 With rapid ventricular response Criteria C1: Code 1.5.3 C2: Ventricular rate > 95 Code 1.5.3 S 14 = C1 and C2

307

Supplementary Codes to AV Dissociation 2.3 S 15 With narrow QRS complex Criteria C1: Code 2.3 C2: QRS < 120 ms (in the majority group) Code 2.3 S 15 = C1 and C2 Note: Code 2.3 S 15 indicates that the likely block site is the AV node or His bundle. 2.3 S 16 With wide QRS complex Criteria C1: Code 2.3 C2: QRS ≥ 120 ms (in the majority group) Code 2.3 S 16 = C1 and C2 2.3 S 17 With wide QRS complex and slow ventricular rate Criteria C1: Code 2.3 S 16 C2: Ventricular rate ≤ 45 cpm Code 2.3 S 17 = C1 and C2

The Novacode Criteria for Classification of Myocardial Infarction and Ischemic Abnormalities Waveform Pattern Labels for Coding of Q Wave Abnormalities The Novacode MI coding system is based on the use of a hierarchy of waveform pattern labels (“flags”) to identify Q wave abnormalities (Table B.2). The coder first determines for each ECG lead if flags QS, EQS, E, X, or Z are present, corresponding to patterns in rows Ha, Hb, I, J, and K of Table B. 2 (Flag QS in row Ha = QS wave; Flag EQS in row Hb= if Flag ‘E’, or ‘X’, or ‘Z’ in V1-V5, and ‘QS’ wave in next lead V2-V6; Flag E in row I = initial R < 100 µV; Flag X in row J = initial R < 200 µV; Flag Z in row K = initial R ≥ 200 µV, respectively [see Fig. B. 1, B. 2]). Identification of these flags is essential for reliable serial ECG coding. If present for a given lead, the appropriate flag is entered on the coding entry form; otherwise the coder checks for the presence of Q waves. Q wave durations exceeding the limits 20, 30, 40, and 50 ms carry flags 20, 30, 40, and 50, respectively. An additional symbol “4” is entered with these Q wave duration flags if the R/Q ratio is less than 4 – for example, 30/4 for a Q duration of 30–39 ms with an R/Q ratio less than 4 (R/Q ratios need not be considered for leads aVL, aVF, III, V1, and V2). These flags in the reference and follow-up ECG coding forms determine the prevalent MI codes and MI incidence codes by assigning lead-specific Q scores, listed in Table B. 2. The advantage of this approach is that the ECG coder does not need to memorize any coding criteria or even the Q scores assigned to different abnormal patterns as long as a proper flag is entered for each lead on the coding data entry form. A look-up table can then be used, or a simple algorithm can assign the appropriate scores and classification codes (Fig. B.3 and B.4).

308

In case electronic data entry is not used for ECG coding forms, the scores assigned for different waveform flags are entered for each ECG lead on the coding form. These scores are relatively easy to memorize. It is noted that the Q scores increase uniformly in steps of 10 points for Q wave duration increments of 10 ms, with five extra points added if the R/Q ratio is less than 4 (except for leads aVL, aVF, III, V1 and V2). The weights for the Q scores are otherwise identical for all leads except that they are 5 points lower for leads aVF and III, and 10 points lower for lead aVL. The Q score limits 1). The ECG coder identifies for each lead group the ECG lead exceeding the highest threshold, and the score of this lead defines the score assigned for its lead group. With computer coding, each of the 12 leads is scored separately for ST-segment elevation, ST depression, and T wave patterns, and the lead with the largest score determines the overall score in each lead group. The ST-segment elevation score is used primarily for identification of an evolving ST-T abnormality from acute-phase hospitalization ECGs and is offered as an optional item for coding of regularly scheduled follow-up ECGs.

309

Classification Criteria for Prevalent Myocardial Infarction and Categorization for Risk Stratification The Novacode category 5 contains a hierarchical classification scheme categorizing MI/ ischemia into high, moderate, marginal, or low likelihood (Table B.4). The categories with high and moderate likelihood of MI are considered as major ECG abnormalities and the marginal MI likelihood categories as minor abnormalities. Novacode 5 categories 5.1 – 5.4 contain criteria for old Q wave infarction, category 5.5 represents profound myocardial ischemia, possibly associated with a non-Q wave infarction, and category 5.6 isolates major ST-T abnormalities without significant Q waves. The remaining two categories (5.7 and 5.8) are for borderline Q waves and ST-T abnormalities. The primary focus of Novacode 5 is on the manifestations of coronary heart disease, and for this reason LVH shown by ECG is excluded for classification of codes 5.5 and 5.6. Novacode 5 abnormalities listed in Table B.4 are also used together with additional information on the history of MI to categorize study participants into high-, moderate-, marginal-, and low-risk subgroups for evaluation of the risk of coronary heart disease mortality. Classification of Incident Myocardial Infarctions For classification of incident MI from regularly scheduled follow-up ECGs, the Q score and ST-T score algorithms are identical to those used for evaluating prevalent MIs. The classification of an incident MI is based on the change of the Q score exceeding specified limits and on whether the ST-T has evolved significantly from the reference ECG (Table B.5). Incident MI codes I 5.1 to I 5.4 are ranked according to the likelihood of Q wave MIs. Evolving ischemic repolarization abnormalities are categorized as profound ST-T evolution (code I 5.5), evolving ST-T with nonevolving Q waves (code I 5.6.1), or isolated ST-T evolution (code I 5.6.2). In case of moderate Q wave evolution (grade 1 change, or Q score increase of 15 points), a two-lead involvement is required for the higher-order codes. A borderline Q wave evolution in a single lead without ST-T evolution is included as the lowest category in the incidence code 5 hierarchy (code I 5.7) because chest lead placement errors or changes in QRS patterns due to secondary directional changes (due to respiration, obesity, minor changes with time, poor record quality, etc.) may produce a false ECG event in this category. An evolving ST-T pattern for regularly scheduled follow-up ECGs is defined by an increase of 20 or more points in ST depression or T wave negativity score, without considering ST elevation. For acute-phase, unscheduled hospitalization ECGs, ST-T evolution is defined as an ST elevation score increase in any event ECG of 40 or more points or a change (increase or decrease) in ST elevation score of 20 or more points, with the highest increase in the ST depression or T wave negativity score being 20 or more points in the same or in some other ECG recorded later on in the acute phase (Note 2 in Table B.5). Note 3 in Table B.5 defines criteria for incident acute MI in the presence of left bundle branch block, adapted from the 1996 report of the GUSTO-1 trial.4 Both prevalent and incident Novacode major and minor ECG abnormalities are independent significant predictors of future cardiovascular disease events and mortality.5 310

Novacode Flag

QS

E

X R

R

Z R

FIGURE B.1. Novacode flags for ECG waveform pattern: Flag QS for QS wave; Flag E for initial R 25–99 μV; Flag X for initial R 100–199 μV; Flag Z for initial R ≥ 200 μV, respectively

Novacode Flag EQS V1 V2

or

V2 V3

V3

or

or

V4

V4

V5

or

V5

V6

FIGURE B.2. Flag EQS = if Flag ‘E’, or ‘X’, or ‘Z’ in V1-V5, and ‘QS’ wave in next lead V2–V6

311

Novacode 5 ECG QRS Flag

Group L

Group I

Group S

Group A

aVL

I

-aVR

II

aVF

III

V1

V2

V3

V4

V5

V6

Z

Z

20/4

40/4

50

50

Z

Z

Z

30

40/4

40/4

0

0

0

0

0

0

0

0

0

0

__

__

0

100

ST Elevation (maximum)

0

ST Depression (maximum)

25

T Negative (maximum)

50

Max. Q Score

35

__ __ __

0

__

Max. ST-T Score

20

Novacode 5

5.1

FIGURE B.3. The ECG with codable QRS and ST-T patterns, Q waves in the leads II, aVF, III, and V4-V6, ST-T abnormality in lead I, aVL and V5–V6, producing a myocardial infarction code – Novacode 5.1

Novacode 5 ECG QRS Flag

Group L

Group I

Group S

Group A

aVL

I

-aVR

II

aVF

III

V1

V2

V3

V4

V5

V6

Z

Z

Z

Z

QS

QS

QS

QS

QS

Z

Z

Z

50

0

0

0

0

0

0

0

0

0

__

__

0

0

ST Elevation (maximum)

0

ST Depression (maximum)

50

T Negative (maximum)

100

Max. Q Score

30

__ __ __

0

Max. ST-T Score

__ 20

Novacode 5

5.2

FIGURE B.4. The ECG with codable QRS and ST-T patterns, QS waves in the lead V1-V3 and lead aVF and III, ST-T abnormality in lead I and aVL, producing a myocardial infarction code – Novacode 5.2 312

TABLE B.2. Hierarchy and Definitions of Waveform Patterns and Corresponding Novacode Q Scores for ECG Leads of Four lead Groups.a L (Lateral)

I (Inferior)

(L-I-API) Waveform Pattern A B C D E F G Ha Hb I J K

Q≥ 50 ms R/Q 20 cpm from reference ECG Code I 1.0.3 = C1 and C2 and C3 Incident wandering atrial pacemaker (WAP) Criteria C1: Code 1.1 in event ECG C2: Code 1.0 in reference ECG Code I l.1 = C1 and C2 Incident junctional rhythm (JR) Criteria C1: Code 1.2 in event ECG C2: Code 1.0 in reference ECG Code I 1.2 = C1 and C2 Incident ectopic atrial rhythm (EAR) Criteria C1: Code 1.3 in event ECG C2: Code 1.0 in reference ECG Code I 1.3 = C1 and C2 Incident supraventricular tachycardia (SVT) Criteria C1: Code 1.4 in event ECG C2: Code 1.0.0 or 1.0.1 in reference ECG Code I 1.4 = C1 and C2 I 1.4.1 Incident SVT, rate < 130 cpm Criteria C1: Code 1.4.1 in event ECG C2: Code 1.0.1 or 1.0.2 in reference ECG Code I 1.4.1 = C1 and C2 I 1.4.2 Incident SVT, rate ≥ 130 cpm Criteria C1: Code 1.4.2 in event ECG C2: Heart rate increase ≥ 30 cpm from the reference ECG Code I 1.4.2 = C1 and C2 Incident atrial fibrillation/flutter (AFLF) Criteria C1: Code 1.5 in event ECG C2: No code 1.5 in reference ECG Code I 1.5 = C1 and C2 I 1.5.1 Incident atrial flutter type 1 (AFL1) Criteria C1: Code 1.5.1 in event ECG C2: No code 1.5 in reference ECG Code I 1.5.1 = C1 and C2 I 1.5.1.1 Incident atrial flutter type 1 classic (AFL1C) 318

Criteria C1: Code 1.5.1.1 in event ECG C2: No code 1.5.1 in reference ECG Code I 1.5.1.1 = C1 and C2 I 1.5.1.2 Incident atrial flutter type 1 variant (AFL1V) Criteria C1: Code 1.5.1.2 in event ECG C2: No code 1.5.1 in reference ECG Code I 1.5.1.2 = C1 and C2 I 1.5.2 Incident atrial flutter type 2 (AFL2) Criteria C1: Code 1.5.2 in event ECG C2: No code 1.5 in reference ECG Code I 1.5.2 = CI and C2 I 1.5.3 Incident atrial fibrillation (AF) Criteria C1: Code 1.5 in event ECG C2: No code 1.5.1 in event ECG C3: No code 1.5.2 in event ECG Code I 1.5.3 = C1 and C2 and C3 I 1.6 Incident electronic pacemaker (PM) Criteria C1: Code 1.6 in event ECG C2: No code 1.6 in reference ECG Code I 1.6 = C1 and C2 I 1.6.1 Incident ventricular pacemaker (VPM) or combination pacemaker (CPM) Criteria C1: Code 1.6.1 in event ECG C2: No code 1.6 in reference ECG Code I 1.6.1 = C1 and C2 I 1.6.2 Incident atrial pacemaker (APM) Criteria C1: Code 1.6.2 in event ECG C2: No code 1.6 in reference ECG Code I 1.6.2 = C1 and C2 I 1.7 Incident ventricular tachycardia (VT) Criteria C1: Code 1.7 in event ECG C2: No code 1.7 in reference ECG Code I 1.7 = C1 and C2 I 1.8 Other incident abnormal rhythms Criteria C1: Code 1.8 in event ECG C2: No code 1.8 in reference ECG Code I 1.8 = C1 and C2 I 1.9 Indeterminate incident rhythm (IAR) Criteria C1: Code 1.9 in event ECG C2: No code 1.9 in reference ECG Code I 1.9 = C1 and C2 Note: Supplementary conditions listed under prevalent arrhythmia codes (S 1 through S 16) can also be coded for incident arrhythmic codes. I 2 Incident AV Conduction Abnormalities 319

I 2.0

No codable incident AV conduction abnormalities Criteria C1: Code 2.0 in event ECG Code I 2.0 = C1 I 2.1 Incident first-degree AV block (AVB1) Criteria C1: Code 2.1 in event ECG C2: Code 2.0 in reference ECG C3: PR increase ≥ 40 ms from reference ECG Code I 2.1 = C1 and C2 and C3 I 2.2 Incident second-degree AV block (AVB2) Criteria C1: Code 2.2 in event ECG C2: Code 2.0 in reference ECG Code I 2.2 = C1 and C2 I 2.2.1 Incident second-degree AV block type Wenckebach or Mobitz 1 (AVB2W) Criteria C1: Code 2.2.1 in event ECG C2: Code 2.0 or 2.1.1 in reference ECG Code I 2.2.1 = C1 and C2 I 2.2.2 Incident second-degree singular AV block or type Mobitz 2 (AVB2S) Criteria C1: Code 2.2.2 in event ECG C2: Code 2.0 or 2.1.1 in reference ECG Code I 2.2.2 = C1 and C2 I 2.2.3 Incident second-degree multiple AV block (AVB2M) Criteria C1: Code 2.2.3 in event ECG C2: Code 2.0 or 2.1.1 in reference ECG Code I 2.2.3 = C1 and C2 I 2.3 Incident third-degree or complete AV block (AVB3) Criteria C1: Code 2.3 in event ECG C2: Code 2.0 or 2.1 or 2.2 in reference ECG Code I 2.3 = C1 and C2 I 2.4 Incident ventricular preexcitation (WPW) Criteria C1: Code 2.4 in event ECG C2: Code 2.0 in reference ECG C3: QRS duration increase ≥ 20 ms from reference ECG C4: PR duration decrease ≥ 20 ms from reference ECG Code I 2.4 = C1 and C2 and C3 and C4 I 2.5 New ventricular preexcitation pattern, change not significant Criteria C1: Code 2.4 in event ECG C2: Code 2.0 in reference ECG C3: QRS duration increase < 20 ms from reference ECG C4: PR duration decrease < 20 ms from reference ECG Code I 2.5 = C1 and C2 and (C3 or C4) I 3 Incident Prolonged Ventricular Excitation

320

I 3.0

I 3.1

I 3.2

I 3.3

No incident prolonged ventricular excitation Criteria C1: Code 3.0 in event ECG (QRS < 115 ms) Code I 3.0 = C1 Incident left bundle branch block (LBBB) Criteria C1: Code 3.1 in event ECG C2: Code 3.0 in reference ECG C3: QRS duration increase ≥ 20 ms from reference ECG Code I 3.1 = C1 and C2 and C3 I 3.1.0 Incident LBBB without ECG evidence of incident MI Criteria C1: Code I 3.1 in event ECG C2: Q score increase ≤ 15 from reference ECG Code I 3.1.0 = C1 and C2 I 3.1.1 Incident LBBB with possible incident MI Criteria C1: Code I 3.1 in event ECG C2: Q score ≥ 20 C3: Q score increase 15 or more Code I 3.1.1 = C1 and C2 and C3 Note: Criteria for acute MI in the presence of LBBB are listed in Table B.5, Note 4. Incident right bundle branch block (RBBB) Criteria C1: Code 3.2 in event ECG C2: Code 3.0 in reference ECG C3: QRS duration increase ≥ 20 ms Code I 3.2 = C1 and C2 and C3 I 3.2.0 Incident RBBB without ECG evidence of incident MI Criteria C1: Code I 3.2 in event ECG C2: Q score increase less than 15 from reference ECG Code I 3.2.0 = C1 and C2 I 3.2.1 RBBB with possible incident MI Criteria C1: Code I 3.2 in event ECG C2: Q score ≥ 20 in event ECG C3: Q score increase 15 or more from reference ECG Code I 3.2.1 = C1 and C2 and C3 Incident indeterminate ventricular conduction delay (IVCD) Criteria C1: Code 3.3 in event ECG C2: Code 3.0 in reference ECG C3: QRS duration increase ≥ 20 ms Code I 3.3 = C1 and C2 and C3 I 3.3.0 Incident IVCD without ECG evidence of incident MI Criteria C1: Code I 3.3 in event ECG C2: Q score increase less than 15 from reference ECG Code I 3.3.0 = C1 and C2 I 3.3.1* Incident IVCD with possible incident MI 321

I 3.4

I 3.5

Criteria C1: Code I 3.3 in event ECG C2: Q score ≥ 20 in event ECG C3: Q score increase 15 or more from reference ECG Code I 3.3.1 = C1 and C2 and C3 New borderline prolonged ventricular exaltation Criteria C1: Code 3.4 in event ECG C2: Code 3.0 in reference ECG C3: QRS duration increase ≥ 20 ms from reference ECG Code I 3.4 = C1 and C2 and C3 New bundle branch block, QRS duration increase < 20 ms Criteria C1: Code 3.1 or 3.2 or 3.3 in event ECG C2: QRS duration increase < 20 ms from reference ECG Code I 3.5 = C1 and C2 I 3.5.0 New bundle branch block with QRS duration increase < 20 ms and with no ECG evidence of incident MI Criteria C1: Code I 3.5 in reference ECG C2: Q score increase less than 15 from the reference ECG Code I 3.5.0 = C1 and C2 I 3.5.1 New bundle branch block with QRS duration increase < 20 ms and possible incident MI Criteria C1: Code I 3.5 in reference ECG C2: Q score increase 15 or more from the reference ECG Code I 3.5.1 = C1 and C2

I 4 Incident Prolonged Ventricular Repolarization I 4.0

I 4.1

No incident prolonged ventricular repolarization C1: QTI < 112 in event ECG C2: QTI ≥ 112 in event ECG and QTI < I12 in reference ECG and QTI increase 400 µV from reference ECG Code I 6.1 = C1 and C2 and C3 New LVH in ECG 2, change not significant Criteria C1: Code 6.1 in event ECG C2: (RaVL + SV3) increase ≤ 400 µV from reference ECG Code I 6.2 = C1 and C2 Note: For risk analysis, the following optional criteria are suggested: LVH progression Criteria C1: (RaVL + SV3) increase > 400 µV from reference ECG C2: ST-segment depression or T wave negativity score increase ≥ 20 points Code I 6.3 = C1 and C2 LVH regression Criteria C1: (RaVL + SV3) decrease > 400 µV from reference ECG Code I 6.4 = C1 Note: Incident and regression codes for other abnormalities are not defined in this version of the Novacode due to unavailability of criteria or limits for short-term biologic and technical variation.

***Update from the 1998 article (2) I 7 Incident Left Atrial Enlargement (LAE) I 7.0

I 7.1

No incident LAE Criteria C1: Code 7.0 in event ECG Code I 7.0 = C1 Incident LAE Criteria C1: Code 7.1 in event ECG C2: Code 7.0 in reference ECG Code I 7.1 = C1 and C2

I 8 Incident Right Ventricular Hypertrophy (RVH) I 8.0

No incident RVH Criteria C1: Code 8.0 in event ECG Code I 8.0 = C1 I 8.1 Incident RVH Criteria C1: Code 8.1 in event ECG C2: Code 8.0 in reference ECG Code I 8.1 = C1 and C2 I 9 Incident Right Atrial Enlargement (RAE)

323

I 9.0

I 9.1

No incident RAE Criteria C1: Code 9.0 in event ECG Code I 9.0 = C1 Incident RAE Criteria C1: Code 9.1 in event ECG C2: Code 9.0 in reference ECG Code I 9.1 = C1 and C2

I 10 Incident Fascicular Block I 10.0 No incident Fascicular Block Criteria C1: Code 10.0 in event ECG Code I 10.0 = C1 I 10.1 Incident Left Anterior Fascicular Block (LAFB) Criteria C1: Code 10.1 in event ECG C2: Code 10.0 in reference ECG Code I 10.1 = C1 and C2 I 10.2 Incident Left Posterior Fascicular Block (LPFB) Criteria C1: Code 10.2 in event ECG C2: Code 10.0 in reference ECG Code I 10.2 = C1 and C2

References 1. Rautaharju PM, Calhoun HP, Chaitman BR. Novacode serial ECG classification system for clinical trials and epidemiological studies. J Electrocardiol 1992;24(suppl):179-187. 2. Rautaharju PM, Park LP, Chaitman BR, Rautaharju F, Zhang ZM. The Novacode criteria for classification of ECG abnormalities and their clinically significant progression and regression. J Electrocardiol 1998;31(3):157-187. 3. Selvester R. Wagner G, Hindman N. The Selvester QRS scoring system for estimating myocardial infarct size. The development and application of the system, Arch Intern Med. 1985;145:1877-1881. 4. Sgarbossa EB, Pinski SL, Barbagelata A, et al. The GUSTO-1 (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries) Investigators. Electrocardiographic diagnosis of evolving acute myocardial infarction in the presence of left bundle-branch block. N Engl J Med. 1996; 334:481-487. 5. Denes P, Larson JC, Lloyd-Jones DM, Prineas RJ, Greenland P. Major and minor ECG abnormalities in asymptomatic women and risk of cardiovascular events and mortality. JAMA. 2007;298 (9):978-985.

324

Appendix C Major and Minor ECG Abnormalities for Population Comparisons with Minnesota Code and Novacode Equivalents Major Abnormalities Abnormality

Minnesota Codes

Novacodes

Major Q wave abnormalities (Old prevalent MI)

MC 1-1, 1-2

NC 5.1, 5.2, 5.3

Minor Q wave abnormalities plus ST-T abnormalities (Possible old MI)

MC I-3 plus MC 4-1 or 4-2, or 5-1 or 5-2

NC 5.4

Major Isolated ST-T abnormalities

MC 4-1 or 4-2 or 5-1 or 5-2

NC 5.5, 5.6

Complete or intermittent LBBB Complete or intermittent RBBB Nonspecific intraventricular block RBBB with left anterior hemiblock Brugada pattern

MC 7-1 MC 7-2 MC 7-4 MC 7.8 MC 7-9

NC 3.1 NC 3.2 NC 3.3 NC 3.2 plus NC 10.1 ―

Left ventricular hypertrophy plus ST-T abnormalities

MC 3-1 plus MC 4-1 or 4-2 or 5-1 or 5-2

NC 6.1.1

Major QT prolongation

QTI ≥ 116%

NC 4.1.2

Atrial Fibrillation or Flutter (Continuous or intermittent)

MC 8-3

NC 1.5

MC 6-1 MC 6-2 MC 6-4 MC 6-8

NC 2.3 NC 2.2 NC 2.4 NC 1.6

MC 8-2

NC 1.7, 1.8.2, 1.9.2

MC 8-4-2 or MC 8-4-1with HR>140

NC 1.4 or NC 1.3.3, 1.2.3 with HR>140

Major AV conduction abnormalities Third-degree AV block (AVB3) Second-degree AV block (AVB2) Ventricular preexcitation pattern (WPW) Artificial pacemaker Other major arrhythmias Ventricular fibrillation or Ventricular asystole Supraventricular tachycardia (SVT)

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Minor Abnormalities Abnormality

Minnesota Codes

Novacodes

Minor Isolated Q/QS waves Minor ST/T abnormalities High R waves (left ventricular) High R waves (right ventricular) ST segment elevation Incomplete RBBB Incomplete LBBB Minor QT prolongation Short PR interval Long PR interval Left axis deviation Right axis deviation Premature beats (supraventricular) Premature beats (ventricular) Premature beats (combined)

MC 1-3 MC 4-3, 4-4, 5-3, 5-4 MC 3-1, 3-3, 3-4 MC 3-2 MC 9-2 MC 7-3 MC 7-6, 7-7 QTI ≥ 112% MC 6-5 MC 6-3 MC 2-1 MC 2-2 MC 8-1-1 MC 8-1-2 MC 8-1-3, 8-1-5

Wandering atrial pacemaker Sinus tachycardia Sinus bradycardia Supraventricular rhythm persistent Low voltage QRS High amplitude P wave Left atrial enlargement (LAE) Fragmented QRS (Early Repolarization)a

MC 8-1-4 MC 8-7 MC 8-8 MC 8-4-1 MC 9-1 MC 9-3 MC 9-6 MC 7-10 MC 9-7a

NC 5.7 NC 5.8 NC 6.1.0 NC 8.1 (Event ECG I-5.5) NC 3.4.1 NC 3.4.2, 10.1, 10.2 NC 4.1.1 ― NC 2.1 ― ― NC 1.0.A.1, 1.0.A.2 NC 1.0.A.3 NC 1.0.A.1, 1.0.A.3, (with NC 1.1) NC 1.1 NC 1.0.3 NC 1.0.2 NC 1.2, 1.3 ― NC 9.1 NC 7.1 ― ―

a

If Early Repolarization is shown to be independently predictive of future mortality

326

Index 1-Codes, 16, 34–48, 128, 220, 222 2-Codes, 49–54 3-Codes, 55–59, 187, 220, 232 4-Codes, 60, 63, 75–80 5-Codes, 60, 64–97, 203, 220, 248, 254, 255 6-Codes, 98, 105–110, 140–143 7-Codes, 111, 119–132 8-Codes, 134–158 9-Codes, 159–185 A Aberrant ventricular conduction, 110 Acute myocardial infarction, 233–257, 308–316 Arrhythmias, 134–158 Atrial flutter, 151, 184, 307 Atrial fibrillation, 150, 184, 307 A-V dissociation, 155–157 B Beats to be measured, 13 Bifascicular block, 129 Biologic variability, 224 Bipolar limb leads, 6 Brugada pattern, 131, 132 C Calibration deflection, 13, 159–161 Chest leads, 8 Coding forms, 203–205 Criteria for serial change, 226–262 D Depolarization, 3 Digital Records, 15 E E point, 208, 214 Early repolarization, 170, 171 ECG leads, 6 ECG recording, 207–225 Electrode positions, 207, 212–215 Electronic (artificial) pacemaker, 110 Electronic records, see Digital Evolving ST segment elevation, 231 Evolving ST depression, 231 Evolving T wave inversion, 227 Evolving Q waves, 227–230

F Fasting, 206 Forms, see Coding form Fragmented QRS, 132–133 Frontal plane QRS/T angle, 265 Fusion beats, 138, 140, 141 H Heart block complete (third degree), 105 Heart block (second degree), 105–107 Heart block (first degree), 107 Heart rate, 187–190 Heart rate variability, 266–268 High R-wave (MC 3), 55–59 History, 1 I Intraventricular block (non-specific), 126 Incompatible codes, 284 J J Point, 60–79, 115, 170, 171 J Point depression, 63, 67, 72–79, 93 J Point elevation, 67, 162–165 L Lead reversals, 171–185 Left anterior fascicular block, 128 Left axis deviation, 50 Left bundle branch block (LBBB), 121, 122, 128 Left ventricular hypertrophy, 55–59, 232, 302 Left Atrial hypertrophy, 159, 170, 383 Low QRS amplitude, 159–161 M Major ECG abnormalities by Minnesota code, 325 Major ECG abnormalities by Novacode, 325 Mathematical symbols, 15 Measurement differences, 15 Measuring devices, 10 Measuring loupe, 12 Minor ECG abnormalities by Minnesota code, 326 Minor ECG abnormalities by Novacode, 326 Mobitz type I heart block, 107 Mobitz type II heart block, 105, 107, 153, 154

327

N Novacode, 287–324 Novacode criteria, 287–324 Novacode criteria for myocardial infarction, 308–316 Novacode criteria for serial change myocardial infarction, 308–315 Novacode/Minnesota code equivalents, 287–289, 325–326 P P wave amplitude, 166 P wave duration, 170 P wave offset (QRS onset), 98, 101 P wave onset, 98, 101 Persistent ventricular rhythm, 148 Plastic ruler, 13 Position for ECG recording, 207–208 PR interval, 98–105 Premature beats supraventricular, 134–140, 144–146 Premature beats ventricular, 137–146, 149 P-terminal force, 170 Q Q wave amplitude, 19 Q wave codes by site, 277, 278 Q wave onset, 22, 99 Q wave duration, 15, 21, 22, 222, (309, 310?) QRS axis, 49–54, 191–195 QRS duration, 111–118, 222 QRS onset, 18, 26, 50, 74, 98, 101–103, 119, 125, 200, 201 QRS offset, 111–118 QRS/T matrix, 264 QRS transition zone, 167–169 QS waves, 16–20, 23–26, 28, 32–34, 45, 47, 48 QT interval, 200–202 Quality of ECG recording, 216–218 Quality control of ECG data, 223–225 Quality control of visual coding, 270–275 Quality control of digital coding, 275 QRS/T simple, 264 QRS/T frontal, 265 R Rate corrected QT interval, 200 R peak duration, 119–122, 129, 130, 140 R wave voltage, 55–59 R wave amplitude, 24–29, 125, 196, 227 R wave initial amplitude, 125 R wave terminal amplitude, 125, 127 Ratio Q/R, 33–35, 41, 45

Recording paper grid, 10 Recording form, 203 Repolarization, 5 Right axis deviation, 51, 52 Right bundle branch block (RBBB), 122–124, 259 S S wave amplitude, 120, 126, 197 Serial ECG change, 226–261 Short PR interval, 109 Single channel electrocardiographs, 207 Sino-atrial arrest, 153–154 Sino-atrial block, 155 Sinus bradycardia, 158 Sinus tachycardia, 157 Spatial QRS/T angle, 264, 265 Spatial T axis, 265 ST segment codes by site, 279 ST segment depression, 60, 63 ST segment elevation, 162–165, 170 ST segment slope, 71–74 Summary of Minnesota codes, 277–286 Supraventricular rhythm, 152, 153 Suppression codes, see Incompatible codes T T wave amplitude, 86–88, 90, 93, 169–171, 198–199, 255 T wave axis, 5, 54 T wave codes by site, 280 T wave offset, 201, 202 T wave negative, 82–84 T wave diphasic, 81, 82, 86, 89, 90, 95, 131, 198, 199 Terminal R wave, 29, 30 The electricity part of the ECG, 2–5 U Unipolar limb leads, 7 V Ventricular asystole, 147 Ventricular fibrillation, 147 Ventricular parasystole, 149 Ventricular tachycardia, 149 Visual records, 15, 270 W W pattern QRS, 31, 32 What is the Electrocardiogram or ECG?, 1 Wolff-Parkinson-White (WPW), 108, 142

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