VERITAS Adult and Pediatric Resting ECG Physicians Guide Rev A1

Copyright © 2012 by Mortara Instrument, Inc. 7865 N. 86th Street Milwaukee, Wisconsin 53224

This document contains confidential information that belongs to Mortara Instrument, Inc. No part of this document may be transmitted, reproduced, used, or disclosed outside of the receiving organization without the express written consent of Mortara Instrument, Inc. Mortara is a registered trademark of Mortara Instrument, Inc. VERITAS is a trademark of Mortara Instrument, Inc. V7.20

TABLE OF CONTENTS RHYTHM STATEMENTS Rhythm Statements and Modifiers ... 3 Rhythm Statements... 3 Rhythm Statement Criteria ... 3 Modifiers ... 6 Modifiers Used with Atrial Fibrillation or Flutter ... 6

MEDIAN BEAT FORMATION AND MEASUREMENTS Simultaneous Acquisition ... 7 Median Beat Formation ... 7 Global Measurements ... 8 QT ... 8 QRS ... 8 PR ... 8 RR ... 8 Individual Lead Measurements ... 8

ADULT CRITERIA Arm Lead Reversal and Dextrocardia ... 9 Ventricular Preexcitation ... 10 Atrial Enlargement ... 11 Axis Deviation ... 11 Low Voltage ... 12 S1-S2-S3 Pattern ... 12 Pulmonary Disease ... 13

ADULT CONDUCTION ABNORMALITIES Right Bundle Conduction ... 15 Left Bundle Conduction ... 17 Non Specific Conduction Abnormality ... 19

ADULT HYPERTROPHY Right Ventricular Hypertrophy... 21 Left Ventricular Hypertrophy ... 22 Voltage Criteria ... 23

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TABLE OF CONTENTS

ADULT MYOCARDIAL INFARCT Myocardial Infarct Discussion... 25 Anterior Infarct ... 26 Septal Infarct ... 28 Anteroseptal Infarct ... 29 Lateral Infarct ... 30 Anterolateral Infarct ... 31 Inferior Infarct ... 32 Inferior Infarct with Posterior Extension ... 33 Infarct Suppressions ... 33

ADULT ST ELEVATION ST Segment Elevation ... 35 Early Repolarization ... 35 Pericarditis ... 36 Anterior and Septal Epicardial Injury ... 37 Lateral Epicardial Injury... 39 Inferior Epicardial Injury ... 41

ADULT ST DEPRESSION Minimal and Moderate ST Depression ... 43 Subendocardial Injury ... 44

ADULT T WAVE ABNORMALITIES T Wave Abnormality, Ischemia... 45 T Wave Abnormality, Nonspecific ... 47 QT Interval ... 48

ADULT BRUGADA Brugada ... 49

PEDIATRIC CRITERIA Arm Lead Reversal and Dextrocardia ... 51 Wolff-Parkinson-White ... 51 Atrial Enlargement ... 52 Axis Deviation ... 52

PEDIATRIC CONDUCTION ABNORMALITIES Right Bundle Conduction ... 53 Left Bundle Conduction ... 53 Ventricular Conduction Delay ... 54

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TABLE OF CONTENTS

PEDIATRIC HYPERTROPHY Right Ventricular Hypertrophy... 55 Left Ventricular Hypertrophy ... 58

PEDIATRIC ST SEGMENT ABNORMALITIES ST Segment Elevation ... 61 ST Segment Depression ... 62

PEDIATRIC T WAVE ABNORMALITIES T Wave Abnormality, Ischemia... 63 QT Prolongation ... 67 Brugada Pattern ... 67

PEDIATRIC TRICUSPID ATRESIA Tricuspid Atresia ... 69

PEDIATRIC ENDOCARDIAL CUSHION DEFECT Endocardial Cushion Defect ... 71

PEDIATRIC ATRIAL SEPTAL DEFECT Atrial Septal Defect ... 73

REFERENCE SUMMARY Age Tables ... 75 QRS Axis for Age ... 75 QRS Duration for Age ... 75 Prolonged PR Duration, Bradycardia, and Tachycardia for Age ... 75 V6 R/S Amplitude Ratio for Age ... 76 V1/V3R R/S Amplitude Ratio for Age... 76 Conditions - Rhythm Statements ... 76 Conditions - Contour Statements, Adult... 77 Conditions - Contour Statements, Pediatric... 79

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TABLE OF CONTENTS

VERITAS RESTING ECG INTERPRETATION EVALUATION Methods, Introduction and General Methodology ... 81 Pediatric Ventricular Hypertrophy ... 81 Pacemaker Detection ... 82 Comparison by Categories... 82 Results, Definitions ... 85 Table 1, Rhythm Criteria Truth Matrices ... 87 Table 2, Contour Criteria Truth Matrices ... 89 Table 3, Sensitivity, Specificity and Predictive Accuracies, Rhythm Criteria ... 92 Table 4, Sensitivity, Specificity and Predictive Accuracies, Contour Criteria ... 93

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PREFACE

PREFACE This guide describes the criteria that the Mortara Instrument VERITAS™ Adult and Pediatric Resting ECG Interpretation algorithm utilizes to analyze and provide interpretive statements for 12-lead ECGs. Adult criteria are considered for patient ages 16 years and older. Adult descriptions are detailed in the first sections of this guide. Pediatric criteria are considered for patient ages 15 years and younger. Pediatric descriptions are detailed in the last sections of this guide. Interpretive statements have two components, the actual interpretive text, and the optional reason statement, which immediately follows in each statement in this Physician’s Guide and provides a synopsis of the principle criteria used to reach the specified conclusion. The intention is to provide these reason statements where users find them helpful. They can be omitted on all ECGs via a setup function on the electrocardiograph. Interpretation of all ECGs proceeds in the sequence of the criteria listing. Ordinarily the last valid statement or conclusion reached within a given section supplants all prior statements. A condition statement follows each interpretive statement. Conditions and their meanings are listed in order of increasing severity in the table below: Condition

Meaning

Normal ECG

Normal

Atypical ECG

An unusual pattern has been observed but has no specific significance.

Borderline ECG

Criteria have limited specificity or prognostic significance or where only minimal criteria are met.

Abnormal Rhythm ECG

Abnormal Rhythm

Abnormal ECG

Abnormal

***ACUTE MI***

Criteria for new or recent myocardial infarction are true or an epicardial injury pattern has been detected

No Further Interpretation Possible

Upon detecting the phenomenon in question, no further useful interpretation of the record is possible.

The statement with the most severe condition provides the conclusion added at the bottom of the interpretative statements when printed. The condition for each statement can be found in the Reference Summary.

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PREFACE

Additional statements may be added to the interpretation text. These statements and their meaning are listed in the table below Statement

Meaning

DATA QUALITY MAY AFFECT INTERPRETATION

A lead may have been detached during part of the recording. Normally, an ECG is not acquired in this condition, unless the operator specifically overrides the electrocardiograph. Note that in some print formats, not all leads are visible for the full recording duration.

INTERPRETATION BASED ON A DEFAULT AGE OF 40 YEARS

40 years is used for age-dependent criteria . This may happen if the age and date of birth have not been entered on the electrocardiograph when the ECG was recorded.

INTERPRETATION BASED ON A DEFAULT AGE OF 6 MONTHS

6 months is used for age-dependent pediatric criteria. This may happen if an age of "0 years" has been entered on the electrocardiograph when the ECG was recorded. Note that if Date of Birth was entered, the precise age is automatically calculated, and this statement does not occur.

Precautions The VERITAS algorithm generates both a rhythm classification and a contour classification based upon criteria described in this guide. These criteria may sometimes differ from criteria found in ECG textbooks or published literature which are intended to train or educate human ECG readers. Human readers and computer algorithms have different strengths and weaknesses. Human readers are less precise, but better able to evaluate the overall pattern of an ECG as well as including a patient’s history and presentation in the evaluation. Computer algorithms are more precise in measuring amplitudes and durations, but less able to evaluate the overall pattern of the ECG and unable to consider a patient’s history or presentation. This aspect, coupled with the fact that there are no universally agreed to criteria, means that criteria used for an ECG algorithm will sometimes differ from other published sources. Statements generated by the VERITAS algorithm should always be reviewed by a physician. The ECG algorithm is not intended to replace a physician review of the ECG. Sensitivity and specificity limitations of ECG algorithms, coupled with their inability to incorporate patient history or presentation, underscore the essential need for physician review of any computer generated interpretation statements. Not all Mortara products are equipped with the pediatric resting ECG interpretation feature. Refer to the equipment user manual for proper instructions and precautions pertaining to equipment use. Definitions Abbreviations used in this guide and in some “reason” statements: Abbreviation

Description

STJ

ST segment amplitude at QRS offset

STM

ST segment amplitude at ST segment midpoint

STE

ST segment amplitude at ST segment endpoint

T

Peak of the T wave

SSS

S-wave is present in lead I and lead II and lead III

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RHYTHM STATEMENTS Rhythm Statements and Modifiers VERITAS rhythm statements describe the predominant rhythm in the 10 seconds of analyzed data. A modifier, listed after the rhythm statements, may also be added to more accurately describe the type of rhythm. The main rhythm statements and their criteria follow. Rhythm Statements Sinus Rhythm Ectopic Atrial Rhythm Junctional Rhythm Supraventricular Rhythm Idioventricular Rhythm Uncertain Regular Rhythm Uncertain Irregular Rhythm Atrial Fibrillation Atrial Flutter/Tachycardia Electronic Atrial Pacemaker Electronic Ventricular Pacemaker Qualifications of the above rhythm statements based on rate are also generated. For example: “Sinus” may be Sinus Bradycardia, Sinus Rhythm, or Sinus Tachycardia. These rate qualifications are made for Sinus, Ectopic Atrial, Junctional and Supraventricular rhythm statements. Criteria for limits of Bradycardia and Tachycardia based on age are included in the Reference Summary. Rhythm Statement Criteria The rationale behind generation of the rhythm statements is described in the following sections. It is important to note that these descriptions are intended to provide a general overview of the VERITAS algorithm logic in a compact reference form. As such, some details and dependencies have been intentionally omitted to improve readability and understanding. Electronic Atrial or Ventricular Pacemaker In interpreting resting ECGs where a pacemaker is present, it is important to note that the VERITAS program does not attempt to assess pacemaker performance criteria such as failure to capture or failure to sense. The 10-second ECG is not adequate in duration for an algorithm to make this determination. All pacemaker generated statements are based upon pacing impulses that have been captured and hence resulted in stimulation of atrial or ventricular activity. There are two independent tests for pacemaker detection: hardware-driven detection (hard pace detection) and software-driven detection (soft pace detection). Hard pace detection is based upon triggering hardware flags and the repeated presence of these flags in a minimum number of beats. These hardware flags are based upon detection of “spikes” in the high resolution front-end data stream (10,000 – 40,000 samples/second depending upon ECG front-end) preceding either atrial activity, ventricular activity, or both. If the hard pace criteria are met, then the appropriate pacemaker statement is set and the subsequent soft pace detection step is skipped.

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RHYTHM STATEMENTS

Soft pace detection utilizes the acquisition data stream (1,000 samples/second) and inspects high frequency, “spike” activity, before atrial and ventricular complexes. This secondary test is used to detect impulses that did not pass the hard pace detection due to low amplitude and/or temporally wide pulses. The distinction between atrial and ventricular pacing is made on the basis of the latency between the spike and the QRS complex. The combined results of applying these two tests are presented in the VERITAS Resting ECG Interpretation Evaluation section. If both electronically paced and intrinsic QRS complexes are found, the phrase “-- contour analysis based on intrinsic rhythm” is added to the statement. Most statements based on contour analysis are suppressed for paced complexes, with the exception of the most severe level of ST-elevation statements. Although this can lead to false positive “Acute MI” statements, this was deemed acceptable given the relatively low percentage of artificially paced ECGs in most hospital populations. Atrial Flutter/Tachycardia The Atrial Flutter/Tachycardia statement is generated if flutter waves (P-P) are detected with a rate above 200 and less than 350 beats per minute. Additionally, in the presence of a ventricular rate above 140 beats per minute, a statement of “Possible Atrial Flutter” will be generated. Note that the P-wave axis and PR interval are not defined in the presence of atrial flutter and hence will not be determined by VERITAS. Atrial Fibrillation The Atrial Fibrillation statement is triggered based on the presence of low amplitude or undetected P waves in combination with a disorganized rhythm. A disorganized rhythm is characterized by the lack of “clustering” of RR intervals, while highly clustered RR intervals are indicative of an organized rhythm. The clustering criteria are utilized to distinguish premature atrial contractions, from atrial fibrillation as illustrated in the following RR histograms.

Sample RR histogram of normal conduction. Note single cluster of RR intervals characteristic of normal conduction at steady sinus rate.

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RHYTHM STATEMENTS

Sample RR histogram in presence of SVPBs. Note two clusters of RR intervals. The larger cluster would be associated with the normal conduction, the smaller, shorter RR with SVPBs.

Sample RR interval histogram for atrial fibrillation. Note lack of clustering.

Note that the P-wave axis and PR interval are not defined in the presence of atrial fibrillation and hence will not be determined by VERITAS. Sinus Rhythm Sinus Rhythm is called in the presence of a normal P-wave axis, between -45 and 120 degrees. For a P-wave axis outside of this range, Ectopic Atrial or Junctional Rhythm is considered. Junctional Rhythm The Junctional Rhythm statement is generated in the presence of a superior P-wave axis between -60 and 240 degrees coupled with a short PR interval (less than 140 milliseconds).

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RHYTHM STATEMENTS

Ectopic Atrial The Ectopic Atrial Rhythm statement is generated in instances when the P-wave axis is outside of the criteria for Sinus Rhythm, but the PR interval is not shortened. Supraventricular Rhythm In instances when the QRS is narrow and the rhythm is organized, but no P-wave is detected, a statement of Supraventricular Rhythm is generated. The narrow QRS suggests conduction through the AV node, but the lack of P-wave detection leaves uncertainty as to whether the rhythm is Sinus or Ectopic Atrial in origin. Note that the P-wave axis and PR interval are not defined when no P-wave is detected by VERITAS. Hence, these values will not be determined. Idioventricular Rhythm The Idioventricular Rhythm statement is generated with a slow (less than 45 beats per minute), wide QRS rhythm. Uncertain Regular/Irregular Rhythm The Uncertain Regular Rhythm statement is generated when a wide QRS rhythm with no apparent P-wave and regular RR interval is present. The Uncertain Irregular Rhythm statement is generated when a wide QRS rhythm with no apparent P-wave and irregular RR interval is present. The previous rhythm statements can be qualified with the following modifiers. Modifiers ...with (marked) sinus arrhythmia ...with first degree AV block ("prolonged PR interval for age" for pediatric records) ...with short PR interval ...with second degree AV block, Mobitz Type (I, II) ...with high grade AV block ...with (occasional/frequent) ventricular premature complexes ...with (occasional/frequent) ectopic premature complexes ...with (occasional/frequent) atrial premature complexes ...with (occasional/frequent) supraventricular premature complexes ...in a pattern of bigeminy ...with marked rhythm irregularity, possible non-conducted PAC, SA block, AV block, or sinus pause ...possible atrial flutter (regular rate near 150) ...contour analysis based on intrinsic rhythm (pacemaker rhythm alternated with intrinsic rhythm) ...intermittent ventricular preexcitation/WPW Modifiers Used with Atrial Fibrillation or Flutter ...with (rapid/slow) ventricular response ...with aberrant conduction or ventricular premature complexes

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MEDIAN BEAT FORMATION AND MEASUREMENTS The following summary provides a high-level review of how the Mortara VERITAS algorithm performs automatic ECG measurements. The general flow of how the Mortara algorithm functions is illustrated below.

Simultaneous Acquisition Following 12-lead or 15-lead simultaneous ECG acquisition using front end sampling rates of 10,000 or 40,000 kHz, ECG analysis is performed at 1000 samples/second/channel. Electrocardiographs using a WAM™ or AM12™ acquisition module feature 40,000 kHz sampling, all others feature 10,000 kHz sampling. The high resolution sampling rate is used to detect pacemaker pulses on the surface ECG. All other analysis is performed at the 1000 samples/second data resolution. Median Beat Formation The Mortara algorithm forms mediani beats from all 12 leads of the ECG. Median beats are utilized to minimize the impact of noise present in any given single beat. Multiple global measurements can be determined utilizing the median beats including the PR, QRS, and QT duration. Median beat formation involves the identification of a “primary” beat type within a sequence of beats. This categorization identifies beats which are to be included in the median or representative beat formation. Beats which are not considered part of the “primary” class are not included in the formation of the median. In applying these criteria, beats such as occasional premature ventricular complexes are excluded from the median beat formation. Following selection of beats, the beats are aligned and combined to form the median beat. This concept is schematically illustrated in the figure below.

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MEDIAN BEAT FORMATION AND MEASUREMENTS

Global Measurements With the median beats constructed, a series of “global” measurements can be obtained. These measurements are global in the sense that they are not lead specific, but rather span the 12-lead simultaneous data. In the case of the PR, QRS and QT duration, the VERITAS algorithm determines onsets and offsets by reference to a composite measure of electrical activity reflecting the total activity across all leads. Specific comments for individual measurements follow. QT The Mortara algorithm determines QT from the interval between the earliest ventricular depolarization activity and the latest “end-of-T”, considering all leads. This determination utilizes median beats, which reduce the effects of noise. A composite measure of electrical activity, reflecting the total activity across all leads, is formed from these median beats. This composite measure is then utilized to infer the moment of earliest ventricular depolarization and the latest “end-of-T”. This “global QT” is naturally longer (statistically) than the QT measured in a single lead, due to the impact of isoelectric onsets/offsets in a single lead measurement. Moreover, in the presence of QT interval increases within a single individual’s ECG, concomitant axis shifts of the T wave may cause the full extent of the QT increase to be more accurately recorded by the global QT measure. QRS The VERITAS algorithm determines QRS duration as the earliest QRS onset (as manifested in any of the 12-lead medians) to the latest QRS offset (considering all 12-lead medians). Comments regarding the “global QT” above similarly apply for the “global QRS”. PR Using the 12-lead median beats, the Mortara algorithm determines the PR interval using the global onset for the P wave to the global onset of the QRS. RR The Mortara algorithm utilizes an average RR interval over 10 second period. Individual Lead Measurements Amplitudes and lead specific intervals, unlike global interval duration measurements, are performed on an individual lead basis. These measurements are determined using individual lead median beats and criteria are applied as described in the following sections.

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It should be noted that although the term “median” is used, the median beat is not a statistical median in the formal mathematical sense. It is a combination of both averaging and median techniques applied to the ECG signal.

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ADULT CRITERIA Arm Lead Reversal and Dextrocardia Criteria IF No Q in lead I and R amplitude < 150uV in lead I or Q amplitude > 0 in lead I and P axis > 90 and PR duration ≥ 110 ms and QRS axis > 90 If above criteria are met and R amplitude < 500 µV in lead V6 and Maximum S amplitude > Maximum R amplitude in lead V6 and P amplitude < 20 µV in lead V6 and P' amplitude < -20 µV in lead V6

THEN PRINT “Arm leads reversed” REASON: Inverted P & QRS in lead I

PRINT “Dextrocardia” REASON: Inverted P & QRS in V6

Rationale Simultaneously negative P and QRS contours in lead ‘I’ are unlikely in a properly recorded ECG. If, in addition, the QRS has a Qr (or rSr') configuration, the most probable explanation is that the arm leads are reversed or dextrocardia is present. If lead V6 has a typical upright configuration, arm lead reversal is more likely: otherwise, dextrocardia is the remaining plausible explanation. Although the reason statement for both lead reversal and dextrocardia mentions only the inverted P & QRS, the requirement of Qr/rSr' morphology is important to distinguish these cases from pulmonary disease and right ventricular hypertrophy patterns, where rS configurations are the norm. (Further separation from the latter is ensured by the requirement of an inverted P.)

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ADULT CRITERIA

Ventricular Preexcitation SKIP TEST IF The test for coupled P wave to QRS is negative or PR duration > 170 ms or QRS duration < 100 ms or Heart rate > 120 BPM or QRS duration > 200 ms or PR duration > 100 ms and QRS duration > 160 ms Criteria IF

THEN

PR duration < 140 ms

PRINT “Ventricular preexcitation/WPW”

and Delta wave is present in 2 leads or Delta wave is present in 2 leads and R amplitude > S amplitude in V1 or QRS area ratio ≥ 0.6 in 2 leads of I/V5/V6 and R duration > 30 ms in V2 or Delta wave is present in 2 leads and PR duration is < 140 ms and R amplitude ≤ S amplitude in V1

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ADULT CRITERIA

Atrial Enlargement Criteria IF Heart rate < 120 and P amplitude > 250 µV in any 1 of leads II/III/aVF/V1/V2 Heart rate < 120 and P amplitude > 300 µV in any 1 of leads II/III/aVF/V1/V2 P' amplitude < -100 µV in V1 or V2 and negative P wave area ≥ 400 µV/ms in the same lead P' amplitude < -150 µV in V1 or V2 and negative P wave area ≥ 600 µV/ms in the same lead

THEN PRINT “Possible right atrial enlargement” REASON: 0.25 mV P wave PRINT “Right atrial enlargement” REASON: 0.3 mV P wave PRINT “Possible left atrial enlargement” REASON: -0.1 mV P wave in V1/V2 PRINT “Left atrial enlargement” REASON: -0.15 mV P wave in V1/V2

Rationale The criteria are the customary ones. For those records meeting only minimal criteria, the qualifier “possible” is used to convey this information. Right atrial enlargement is not “read” for rates of 120 or above, because it is unclear whether increased P amplitude at elevated rates should be attributed to enlargement.

Axis Deviation Criteria IF QRS axis < -20

THEN PRINT “Borderline Left axis deviation”

QRS axis < -30

REASON: QRS axis < -20 PRINT “Marked Left axis deviation”

QRS axis > 90

REASON: QRS axis < -30 PRINT “Borderline Right axis deviation”

QRS axis > 100

REASON: QRS axis > 90 PRINT “Marked Right axis deviation”

The total net QRS amplitude in leads I, II, and III is < 33% of the total QRS deflection in leads I, II, and III.

REASON: QRS axis > 100 PRINT “Indeterminate axis”

Rationale The criteria are more or less conventional. (Axis deviation statements are omitted when subsequently identified diagnostic categories may be regarded as the probable cause of the axis deviation.) Whenever the net amplitude is a small fraction of the total QRS deflection in each lead, the measurement of axis is lacking in meaning. The term “indeterminate axis” is used to convey this information.

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ADULT CRITERIA

Low Voltage SKIP TEST IF QRS duration ≥ 120 ms Criteria IF Total QRS deflection < 500 µV in all limb leads

THEN PRINT “Low QRS voltage in extremity leads”

Total QRS deflection < 1000 µV in all V leads

REASON: QRS deflection < 0.5 mV in limb leads PRINT “Low QRS voltage in precordial leads”

If both of the above are true

REASON: QRS deflection < 1.0 mV in chest leads PRINT “Low QRS voltage” REASON: QRS deflection < 0.5/1.0 mV in limb/chest leads

S1-S2-S3 Pattern Criteria IF

THEN

S amplitude > 300 µV in I

PRINT “S1-S2-S3 pattern, consistent with pulmonary disease, RVH, or normal variant”

and S amplitude > 400 µV in II and S amplitude > 700 µV in III or S amplitude > R amplitude in leads I, II & III and S amplitude > 200 µV in leads I, II & III and the test for R' is negative in any of these leads and age > 15

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ADULT CRITERIA

Pulmonary Disease SKIP TEST IF QRS duration ≥ 120 ms Criteria The test for pulmonary disease is based on counting how many of its typical characteristics are present. One point is awarded for each of • Right atrial enlargement • QRS axis < -30 • QRS axis > 90 • QRS axis is indeterminate • S1-S2-S3 pattern • Low voltage in limb leads • Low voltage in chest leads Three points are awarded if QRS net amplitude is negative in lead V5 and the R (and R') amplitude in V6 < 500 µV. IF Cumulative points > 3

THEN PRINT “Pattern consistent with pulmonary disease”

Rationale There is room to doubt whether sufficient ECG criteria exist to diagnose pulmonary disease. However, if at least 4 (from a list of 8 distinct) features common to pulmonary disease are present, then the comment “consistent with” seems prudent.

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ADULT CRITERIA

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