HP M1700 Physician guide

Hewlett-Packard Interpretive Cardiograph

Physician's Guide

ABCDE

HP Part No. M1700-92908

Printed in USA September 1994

Edition 4

E0994

Notice

The information in this documentmaychange without

notice.

Hewlett-Packard makes no warrantyofany kind with

regard to this material, including, but not limited to,

the implied warranties of merchantability and tness

for a particular purpose. Hewlett-Packard shall not be

liable for errors herein or for incidental or consequential

damages in connection with the furnishing, performance

or use of this material.

This document contains or refers to proprietary

information which is protected by copyright. All

rights are reserved. Copying or other repro duction

of this document without prior written permission of

Hewlett-Packard Company is prohibited.

c



Copyright 1990, 1991, 1992, 1993, 1994

Hewlett-Packard Company.

Printing History

May 1990 Edition 1

September 1990 Edition 2

January 1992 Edition 3

September 1994 Edition 4

iii

About This Guide

This guide explains how the clinical ECG reports

are analyzed by an Hewlett-Packard interpretive

cardiograph. It also shows howanHPinterpretive

cardiograph ensures reliable results.

Note

Computerized ECG analysis should always be reviewed

by a qualied physician.

iv

Who Should Read

This Guide?

Information Resource

This guide is intended for physicians who read or review

ECGs produced by a Hewlett-Packard interpretive

cardiograph. It also maybeofinterest to other

healthcare professionals who want to know more about

HP's interpretive cardiographs. The following table

shows where you can nd additional information on

related topics.

How to congure the cardiograph. The

cardiograph.

Description of ECL (the programming

language in which the interpretive

ECL Programmers Reference Manual

Hewlett-Packard

criteria is written).

Complete ECL program listing of all

criteria statements.

Operating instructions and guidelines for

the Hewlett-Packard ECG Management

System.

Note

This book discusses several functions that may not b e

Interpretive Criteria Listing

Hewlett-Packard

ECG Management System manuals, or contact

your Hewlett-Packard customer support

representative.

available on your HP interpretive cardiograph, suchas

oppy-disk storage, mo dem data transmission, extended

measurement report, signal averaged ECG, internal

congurations, alternate patient lead sets or patient lead

congurations. Refer to the

your cardiograph for a guide to the functions available

on your cardiograph.

User's Reference Guide

User's Guide

provided with your

. Order from

. Order from

supplied with

v

Documentation

Map

Documentation Map

If you want to: Use this manual:

Verify that all equipmentis

included

Packing List

Record ECGs

Enter patientID

Make copies of ECGs

Store ECGs

1

Transmit or receive ECGs

Troubleshoot problems

Maintain the cardiograph

Set up the cardiograph

Install battery

Install software

1

Load paper

Congure the cardiograph

Prepare patient

Maintain the cardiograph

Install and use the mo dem

Order supplies

Use lters

Operating Guide

1

User's Reference Guide

1

Understand analysis

1

Note: your cardiograph may not be equipp ed for this function.

Physician's Guide

vi

Contents

1. Why Use an Interpretive Cardiograph?

What You Can Exp ect of the HP ECG

Analysis Program . . . . . . . . . 1-2

2. How Computerized ECG Interpretation has

Developed

3. Understanding Simultaneous 12-Lead Acquisition

Digitizing the ECG . . . . . . . . . . 3-3

Reducing Artifact . . . . . . . . . . 3-5

Common Mode Rejection . . . . . . 3-5

Using Filters . . . . . . . . . . . . . 3-6

Frequency Response Filters . . . . . 3-7

AC Filter . . . . . . . . . . . . . 3-8

Baseline Wander Filter . . . . . . . 3-8

Artifact Filter . . . . . . . . . . . 3-10

Monitoring ECG Quality . . . . . . . 3-10

4. The HP ECG Analysis Program

Understanding the HP ECG Analysis

Program . . . . . . . . . . . . . 4-2

How the HP Interpretive Cardiograph

Measures ECGs . . . . . . . . . . 4-3

Waveform Recognition . . . . . . . 4-4

Comprehensive Measurements . . . . 4-4

Group Measurements . . . . . . . . 4-4

Lead Measurements . . . . . . . . . 4-5

Atrial Rhythm Analysis . . . . . . . 4-5

Global Measurements . . . . . . . . 4-6

Axis Measurements . . . . . . . . . 4-6

Contents-1

The ECG Criteria Language (ECL) . . . 4-7

Categories . . . . . . . . . . . . . 4-7

Sentences . . . . . . . . . . . . . 4-7

Overall Severity . . . . . . . . . . 4-9

Further Information . . . . . . . . . . 4-9

5. The HP Adult ECG Criteria Program

Understanding the HP Adult ECG Criteria

Program . . . . . . . . . . . . . 5-2

Pediatric Age Disclaimer . . . . . . 5-4

Calibration Notice if Not Standard . . 5-4

Technical Quality Statements . . . . 5-5

Electronic Pacemaker . . . . . . . . 5-5

Basic Cardiac Rhythm . . . . . . . 5-5

Premature Beats (Short R-R) . . . . 5-6

Pauses (Long R-R) . . . . . . . . . 5-6

Miscellaneous Arrhythmias . . . . . 5-7

AV Conduction (PR Interval) . . . . 5-8

QRS Axis . . . . . . . . . . . . . 5-9

Ventricular Conduction Delays . . . . 5-10

RightAtrial Enlargement . . . . . . 5-11

RightVentricular Hypertrophy. . . . 5-11

Prominent R or R

0

in V1 . . . . . 5-11

Prominent Q or S in I or V6 . . . . 5-12

RightAtrial Enlargement . . . . . 5-12

Right Axis Deviation in the Frontal

Plane . . . . . . . . . . . . 5-12

ST{T Changes Characteristic of RVH 5-12

Left Atrial Enlargement. . . . . . . 5-12

Left Ventricular Hypertrophy . . . . 5-13

High Voltage in QRS Components . 5-13

Left Axis Deviation in the Frontal

Plane . . . . . . . . . . . . 5-14

Left Atrial Enlargement. . . . . . 5-14

ST{T Changes Characteristic of LVH 5-14

A Prolonged QRS Duration or

Ventricular Activation Time . . 5-14

Chronic Pulmonary Disease . . . . . 5-15

Contents-2

Inferior Infarct . . . . . . . . . . . 5-15

Posterior Infarct . . . . . . . . . . 5-16

Lateral Infarct . . . . . . . . . . . 5-17

Anteroseptal and Anterior Infarct . . . 5-17

Anterolateral and ExtensiveAnterior

Infarct . . . . . . . . . . . . . 5-18

Apical Infarct . . . . . . . . . . . 5-19

Tall T Waves . . . . . . . . . . . . 5-19

Drug and Electrolyte Eects . . . . . 5-19

TWave Abnormalities . . . . . . . 5-19

Ischemia . . . . . . . . . . . . . . 5-21

ST Segment Depression . . . . . . . 5-21

Subendocardial Injury . . . . . . . . 5-22

Combined ST and T Abnormalities . . 5-23

Injury and Ischemia . . . . . . . . . 5-23

ST Segment Elevation . . . . . . . . 5-23

Severity . . . . . . . . . . . . . . 5-24

6. The HP Pediatric ECG Criteria Program

Understanding the H-P Pediatric ECG

Criteria Program . . . . . . . . . 6-2

Pediatric ECG Interpretation . . . . 6-4

Calibration Notice if Not Standard . . 6-4

Technical Quality Statements . . . . 6-4

Electronic Pacemaker . . . . . . . . 6-5

Dextrocardia . . . . . . . . . . . . 6-5

Basic Cardiac Rhythm . . . . . . . 6-5

Sinus Rhythms . . . . . . . . . . . 6-5

Atrial Premature Complex . . . . . . 6-6

Ventricular Premature Complex . . . 6-7

PR Interval . . . . . . . . . . . . 6-7

Wol-Parkinson-White Syndrome . . . 6-7

Ventricular Conduction Delay . . . . 6-7

Right Bundle Branch Block . . . . . 6-7

Left Bundle Branch Blo ck . . . . . . 6-8

RightAtrial Enlargement . . . . . . 6-8

RVH: QRS Voltage Criteria . . . . . 6-8

Right Axis Deviation . . . . . . . . 6-9

Contents-3

RVH: T Wave Criteria . . . . . . . 6-9

RightVentricular Hypertrophy. . . . 6-9

Left Atrial Enlargement. . . . . . . 6-10

LVH: QRS Voltage Criteria . . . . . 6-10

Left Axis Deviation . . . . . . . . . 6-10

LVH: ST Segment and T Wave Criteria 6-11

Left Ventricular Hypertrophy . . . . 6-11

Biventricular Hypertrophy. . . . . . 6-11

Anterior ST Elevation . . . . . . . . 6-11

Inferior ST Elevation . . . . . . . . 6-12

Anterolateral ST Elevation . . . . . . 6-12

Anterior ST Depression . . . . . . . 6-12

Inferior ST Depression . . . . . . . 6-12

Anterolateral ST Depression . . . . . 6-12

Anterior T Wave Changes . . . . . . 6-13

Inferior T Wave Changes . . . . . . 6-13

Anterolateral T Wave Changes . . . . 6-13

Anatomical Diagnoses . . . . . . . . 6-14

Severity.. . . . . . . . . . . . . 6-14

7. Reading the Printed Rep ort

Auto Interpretive Reports . . . . . . . 7-2

Patient Information . . . . . . . . . 7-3

Basic Measurements . . . . . . . . 7-4

Interpretive Information . . . . . . . 7-5

Calibration Pulse . . . . . . . . . . 7-6

Rhythm Strip . . . . . . . . . . . 7-6

Settings . . . . . . . . . . . . . . 7-7

Auto Rep ort Formats . . . . . . . . 7-8

Extended Measurements Report . . . . 7-10

Manual Reports . . . . . . . . . . . 7-11

Cardiograph Settings . . . . . . . . 7-12

Manual Report Formats . . . . . . . 7-13

Contents-4

8. Managing Your ECGs

PageWriter Communications . . . . . . 8-3

ECG Management Systems . . . . . . 8-4

Clinical Rewards . . . . . . . . . . 8-5

CurrentTrends . . . . . . . . . . . 8-6

A. Questions and Answers

B. PatientIDCodeTables

C. The Extended Measurements Rep ort

Morphology Analysis . . . . . . . . . C-3

Individual Lead Measurements . . . . C-3

Cal Factors . . . . . . . . . . . . C-8

Frontal/Horizontal . . . . . . . . . C-9

Analysis Statement Co des . . . . . . C-10

Rhythm Analysis . . . . . . . . . . . C-10

Group Measurements . . . . . . . . C-10

Group Flags . . . . . . . . . . . . C-13

Global Rhythm Parameters . . . . . C-14

Rhythm Grouping of Beats . . . . . C-16

D. Understanding the M1754A Signal-Averaging

Process

Introduction . . . . . . . . . . . . . D-1

M1754A ECG Signal Averaging . . . . D-3

Signal Acquisition . . . . . . . . . D-3

SAECG Technique . . . . . . . . D-3

Lead System . . . . . . . . . . . D-3

SAECG Signal Path . . . . . . . D-4

Signal Amplication . . . . . . D-5

Signal Digitization . . . . . . . D-5

Signal Conditioning . . . . . . . D-5

Template Selection . . . . . . . . . D-6

Signal Averaging . . . . . . . . . . D-7

Beat Rejection . . . . . . . . . . D-8

Noise Reduction . . . . . . . . . D-10

Filtering . . . . . . . . . . . . . . D-11

Contents-5

Measurements . . . . . . . . . . . D-13

QRS Duration . . . . . . . . . . D-13

Terminal RMS Voltage . . . . . . D-14

Low Amplitude Signal Duration . . D-15

Total RMS Voltage . . . . . . . . D-17

Understanding the M1754A ECG

Signal-Averaging Rep ort . . . . . . D-18

Patient Information . . . . . . . . . D-19

Report Settings . . . . . . . . . . D-20

Individual Lead and Vector

Measurements . . . . . . . . . . D-20

Unltered Leads . . . . . . . . . . D-21

Absolute Filtered Leads . . . . . . . D-21

Vector Magnitude . . . . . . . . . D-21

Bibliography. . . . . . . . . . . . . D-22

Glossary

Index

Contents-6

Figures

3-1. Ten Seconds of 12 Leads on an Auto 3x4

Report. . . . . . . . . . . . . . 3-1

3-2. Ten Seconds of 12 Leads on an Auto 6x2

Report. . . . . . . . . . . . . . 3-2

3-3. Digitizing the ECG. . . . . . . . . . 3-3

3-4. The Filter Box on the ECG Report. . . 3-7

4-1. The HP ECG Analysis Pro cess. . . . 4-1

4-2. ECG Morphology Measurements. . . . 4-3

7-1. A Typical Interpretive Report. . . . . 7-2

7-2. An Auto 3x4 Report. (3x4) . . . . . 7-8

7-3. An Auto 3x4 Report with a Rh

ythm

Strip. (3x4, 1R) . . . . . . . . . 7-8

7-4. An Auto 3x4 Report with 3 Rh

ythm

Strips. (3x4, 3R) . . . . . . . . 7-9

7-5. An Auto 6x2 Report. (6x2) . . . . . 7-9

7-6. An Extended Measurements Report

(Morphology). . . . . . . . . . . 7-10

7-7. An Extended Measurements Report

(Rhythm). . . . . . . . . . . . 7-11

7-8. A Manual 3-Lead Format. . . . . . . 7-13

7-9. A Manual 6-Lead Format. . . . . . . 7-14

7-10. A Manual 12-Lead Format. . . . . . 7-14

8-1. Managing ECGs. . . . . . . . . . . 8-2

A-1. A Cabrera Report. (6x2) . . . . . . A-5

A-2. Frontal Plane Lead Axes. . . . . . . A-5

C-1. An Extended Measurements Report.

(Morphology) . . . . . . . . . . C-2

C-2. ECG Morphology Measurements. . . . C-3

C-3. An Extended Measurements Report.

(Rhythm) . . . . . . . . . . . C-10

Contents-7

D-1. The Signal-Averaging Process. . . . . D-4

D-2. The Noise Reduction Curve. . . . . . D-10

D-3. The Vector Magnitude Waveform. . . D-12

D-4. QRS Duration. . . . . . . . . . . . D-13

D-5. Terminal RMS Voltage. . . . . . . . D-15

D-6. Low Amplitude Signal Duration. . . . D-16

D-7. The RMS Voltage. . . . . . . . . . D-17

D-8. The SAECG Rep ort. . . . . . . . . D-18

Contents-8

Tables

5-1. Calibration . . . . . . . . . . . . 5-4

5-2. Borderline and Abnormally Prolonged

PR Intervals (ms) . . . . . . . . 5-8

5-3. T Wave Abnormality Lo calization . . 5-20

5-4. ST Segment Depression Localization . 5-22

5-5. ST Segment Elevation Lo calization . . 5-24

6-1. Calibration . . . . . . . . . . . . 6-4

6-2. Age vs. Ventricular Rate for Sinus

Rhythms . . . . . . . . . . . . 6-6

7-1. Basic Measurements . . . . . . . . 7-4

7-2. Calibration Signals . . . . . . . . . 7-6

B-1. Patient ID Fields . . . . . . . . . . B-2

B-2. Medication and Diagnosis Codes . . . B-3

B-3. Race Co des . . . . . . . . . . . . B-4

B-4. Severity Co des . . . . . . . . . . . B-4

D-1. Rep ort Settings . . . . . . . . . . D-20

D-2. Individual Lead and Vector

Measurements . . . . . . . . . . D-20

Contents-9

Why Use an Interpretive Cardiograph?

While a computer-interpreted ECG rep ort is not a

substitute for overreading by a qualied physician,

computerized interpretation is a very useful tool in

improving physician and sta productivity. The

program's basic measurements and interpretation can

help the physician save time when overreading reports.

The HP ECG Analysis program is highly eectiveat

screening normal ECGs. ECGs requiring comment

already have the initial computerized commentary on

them, so the physician has a head start on the nal

interpretation.

The HP ECG Analysis Program makes quick and

consistent measurements of the ECG. It makes detailed

measurements over the entire ECG, providing more data

for a more accurate interpretation. The program can

help identify problem areas for the physician. This saves

time for the physician or editing technician who may

only need to add, delete or mo dify a few statements.

1

Those who read ECGs infrequently may nd the

interpreted rep orts to be useful training to ols. They can

refer to reasons asso ciated with each statement for the

rationale for why a particular condition was suggested.

Why Use an Interpretive Cardiograph? 1-1

What You Can

Expect of the HP

ECG Analysis

Program

The HP ECG Analysis Program provides an analysis of

the amplitudes, durations and morphologies of the ECG

waveform. The ECG waveform analysis is based upon

standards of interpretation of these parameters as well as

upon calculations of the electrical axis and relationship

between leads.

Just as cardiologists may disagree on interpretations,

occasionally there is some disagreementbetween an

interpretation given by the computer program and that

made by a cardiologist. The interpreted ECG is a tool to

assist the physician in making a clinical diagnosis. It is

best used in conjunction with the physician's knowledge

of the patient, the results of the physical examination,

the ECG tracing, and other ndings.

1-2 Why Use an Interpretive Cardiograph?

How Computerized ECG Interpretation has

Developed

Development of computer-assisted ECG analysis began

in the 1960s. Initially only used in research facilities,

computer interpretation has developed into an accepted

tool for physicians.

Hewlett-Packard entered the computerized ECG analysis

eld in 1968 when it obtained and oered sev

existing analysis programs. In 1975 Hewlett-Packard

introduced one of the rst commercially available

systems to provide long-term ECG storage. ECGs were

stored, retrieved and managed on this rst HP 5600C

ECG Management system. The system analyzed ECGs

using the existing analysis programs. Hewlett-Packard

was able to identify some unique contributions it could

make to the eld of ECG analysis, which resulted in

the 1978 introduction of the ECG Criteria Language

(ECL). ECL enabled HP to write the Hewlett-Packard

Adult Criteria program, which replaced all of the earlier

programs.

2

eral

In 1980 Hewlett-Packard intro duced the HP 4700

PageWriter cardiograph, which digitally acquired ECGs.

In 1983 it became p ossible to transmit ECGs digitally

over phone lines to the HP 5600C ECG Managemen

system.

How Computerized ECG Interpretation has Developed 2-1

t

Computerized ECG interpretation b ecame available

on the cardiograph in 1983 when Hewlett-Packard

introduced the HP 4760AI PageWriter Intelligent

cardiograph. The proven ECG analysis program from

the HP 5600C was implemented on the HP 4760AI

cardiograph. Hewlett-Packard's Pediatric Criteria

program was also introduced in 1983 for b oth the HP

ECG Management system and the cardiograph.

Your HP interpretive cardiograph continues the tradition

of improving the p erformance of the analysis program.

The ECG Measurement program has been enhanced and

is now in its seventh revision. Simultaneous twelve-lead

acquisition allows detection of waveform onsets and

osets more accurately. The additional waveform

information helps to dene each beat's components

better in the measurements section of the analysis. This

increased denition produces more consistent results

overall.

The Criteria program continues to evolve. Since its

initial release, the program has undergone several

changes. The current release is the eighth revision of

the Adult analysis criteria and the fourth revision of

the Pediatric analysis criteria. Suggestions made byan

advisory group of respected electro cardiographers are

evaluated regularly for inclusion in subsequent releases.

2-2 How Computerized ECG Interpretation has Developed

Understanding Simultaneous 12-Lead Acquisition

Computer-assisted ECG analysis begins with acquiring

high quality, accurate ECG waveforms. Your HP

interpretive cardiograph simultaneously acquires up to

16 ECG leads (depending on the mo del) and analyzes 12

leads. Although the printed recording doesn't show it,

the Hewlett-Packard ECG Analysis Program uses the

full ten second recording in each lead. Figure 3-1 shows

how the Auto 3x4 format displays consecutive 2.5 second

segments of 12 leads, three leads at a time. Figure 3-2

shows how the Auto 6x2 format displays consecutive5

second segments of 12 leads, six leads at a time.

3

Figure TLD34 here.

Figure 3-1. Ten Seconds of 12 Leads on an Auto 3x4 Report.

Understanding Simultaneous 12-Lead Acquisition 3-1

Figure TLD62 here.

Figure 3-2. Ten Seconds of 12 Leads on an Auto 6x2 Report.

Besides the conventional 12 leads, your cardiograph may

have the capability to use one of the following sets of

supplemental leads:

pediatric leads V4R, V3R, V7

or Frank leads X, Y, Z

or research leads VX1, VX2, VX3, VX4

The p ediatric leads may b e used for conrming certain

right-sided interpretations in pediatric and, o ccasionally,

in adult applications. The research leads provide four

additional V-type leads that may be placed at your

discretion and recorded simultaneously with the standard

12 leads. Because their lo cation is not preassigned as

with the pediatric leads, they are simply labeled VX1

through VX4. The Frank leads, X, Y, and Z,

3-2 Understanding Simultaneous 12-Lead Acquisition

capture a three-dimensional, orthogonal view of the

heart's electrical activity. If they are available on your

cardiograph, any of these supplemental leads can be

displayed as rhythm strips with the conventional 12-lead

ECG. Regardless of which supplemental set of leads you

choose, all ECG waveforms are acquired simultaneously.

Digitizing the ECG

The continuous, analog ECG signal at the bo dy surface

is digitized at the input to the cardiograph. On some

cardiographs the signals are digitized internally,on

others, they are digitized by the patient module (as

shown in Figure 3-3). The ECG waveform data is

captured at a sample rate that signicantly exceeds the

250 samples per second at 5V resolution requirements

of the Hewlett-Packard Analysis Program. It is also fast

enough to accurately detect pacemaker pulses.

A/D Conversion

Patient Mo dule

Cardiograph

Figure 3-3. Digitizing the ECG.

Understanding Simultaneous 12-Lead Acquisition 3-3

As the ECG is converted to digital form, it is digitally

ltered. Not only is this approach more exible, it

provides superior results when compared to analog

ltering. The HP cardiograph's digital signal processing

ensures the most accurate reproduction of the patient's

ECG waveforms.

The American Heart Association's 1989

Recommendations for standardization and specications

in automated electrocardiography: bandwidth and digital

signal processing,

for adult ECGs to 125 Hz and for infant ECGs to

150 Hz. These recommendations are met by the data

acquisition scheme in all HP interpretive cardiographs.

The HP interpretive cardiograph's input circuitry has

a dynamic range that meets or exceeds current AAMI

standards.

extended the recommended bandwidth

3-4 Understanding Simultaneous 12-Lead Acquisition

Reducing Artifact

Electrical interference, patient respiration, patient

movement and muscle tremors can add noise and artifact

to the ECG signal. Poor quality electro des or inadequate

patient preparation can also degrade the ECG signal.

Your HP interpretive cardiograph has b een carefully

designed to substantially reduce artifact and accurately

record the ECG signal.

Common Mode

Rejection

Some of the noise sources that interfere with the ECG

signal are common to each electrode attached to the

patient. To the extent that they have an identical eect

on the ECG signal in each lead, they are removed

from the ECG by the cardiograph's input circuitry as

the signal is acquired and digitized. The amountof

reduction of these

common mode

signals is referred to as

the common mode rejection ratio. The common mo de

rejection ratio of your HP interpretive cardiograph's

input circuitry meets or exceeds current AAMI

standards.

The eects of ACinterference on the ECG are twofold,

common mode and dierential mode. The interference

which is common to all electrodes (common mo de) is

removed in the HP interpretive cardiograph's input

circuitry.Even though this circuitry greatly reduces

common mode noise, go od ECG technique is still

important. In the case of dierential mode, the magnetic

elds associated with electrical p ower interact with

the lead wires. This induces electrical signals which

appear as high frequency noise on the ECG. Ho

wmuch

distortion there is depends on the size of the loop

created by the lead wire and its orientation. A go od way

to prevent this distortion is to align the lead wires with

the patient's bo dy.

Understanding Simultaneous 12-Lead Acquisition 3-5

Using Filters

Computerized signal processing in the HP interpretive

cardiograph removes noise and artifact while minimizing

distortion of the ECG waveform. A sophisticated set of

digital lters can be selected by the op erator (or during

conguration) to optimize the ECG waveform. Digital

lters have the advantage over traditional analog lters

in their abilit y to be nely tuned to selected frequencies.

Unlike analog lters, digital lters are very stable over

time and temperature, meaning that ECGs taken under

various conditions will receive the same high quality

ltering.

With the exception of the AC lter, whichisvery

selective, there is always some tradeo in ltering

between delity and clarit y of the ECG trace. The more

ltering applied to the signal, the greater the possibility

of removing details of the ECG signal with noise of the

same frequency.

There are a variety of noise sources which can potentially

degrade the repro duction of the ECG signal. Sev

types of lters can be used in y

cardiograph to counteract them and reduce the artifact

in the ECG. In the lower right-hand corner of the HP

interpretive ECG report is a bo

about the ltering options used on each ECG. Note that

your PageWriter mayor may not have all of these lters.

our HP interpretive

x containing information

eral

3-6 Understanding Simultaneous 12-Lead Acquisition

Insert artwork here.

Figure 3-4. The Filter Box on the ECG Report.

Frequency Response

Filters

These lters suppress frequencies at the high and lo

ends of the ECG signal spectrum. The a

frequency response lter settings are 40, 100 and 150 Hz.

In 1989, the American Heart Association recommended

that frequencies up to 125 Hz be recorded for adult

ECGs and that frequencies up to 150 Hz be recorded

for pediatric ECGs (American Heart Asso ciation's 1989

Recommendations for standardization and specications

in automated electrocardiography: bandwidth and digital

signal processing

records and analyzes all ECGs with frequencies up

to 150 Hz. The 40 and 100 Hz lters only aect the

printed report. They result in a smoother-lo oking ECG

waveform, at the expense of eliminating some of the ne

detail in the signal. Small deections, notches, and slurs

may b e distorted or may disapp ear altogether if one of

these lters is selected for the Auto frequency response.

). Your HP interpretive cardiograph

vailable high

w

Understanding Simultaneous 12-Lead Acquisition 3-7

The available low frequency response lter settings are

0.05, 0.15, and 0.5 Hz. The 0.5 Hz lter is also the

baseline wander lter. The low frequency response lter

settings aect analyzed and printed ECGs.

The frequency response of the ECG is indicated in the

ECG rep ort's lter box.

AC Filter

Baseline Wander

Filter

The AC lter adaptively detects the ACinterference in

the ECG signal and very selectively removes it without

aecting the ECG. This lter aects analyzed and

printed ECGs.

The AC lter removes interference created by the

magnetic elds associated with electrical power

interacting with the lead wires. The frequency of the

ACinterference is very stable at 60 or 50 Hz, so the A

C

lter can remove the AC noise and leave the ECG signal

intact.

The line power, or AC, lter is indicated in the second

position of the ECG report lter bo

"(your cardiograph may also report the congured

\

line frequency 50 or 60). If the lter bo

xby the symbol

x does not

contain this symbol, the AC lter was not used for the

ECG.

Baseline wander is the term used to describe the slow

(typically 0.1{0.2 Hz) drifting of the ECG baseline up or

down during the ECG recording. Baseline wander may

result from patient respiration or from other sources.

Severe baseline wander can make it dicult to determine

the true wave shap es in the ECG.

3-8 Understanding Simultaneous 12-Lead Acquisition

Early analog attempts to suppress the eects of baseline

wander resulted in \smearing" the QRS complex

into the ST segment. In 1975, the American Heart

Association addressed this problem by recommending

that frequencies as low as 0.05 Hz be preserved in the

ECG signal to prevent the then common ST segment

distortion. (American Heart Association's 1975

Recommendations for standardization of leads and of

specications for instruments in electrocardiography and

vectorcardiography.

)

Since the advent of digital ECG acquisition in the

1980's, eective baseline wander suppression techniques

that do not distort the ST segmenthave been a part

of Hewlett-Packard's cardiographs. While the lower

frequency limit of 0.15 Hz, whichwe recommend for

normal use, eliminates baseline wander from most ECGs,

you may occasionally need extra suppression. The

4

Filter

5

key on the key panel can b e congured to allow the

operator to turn on the baseline wander lter when

needed. The baseline wander lter suppresses frequencies

below 0.5 Hz. It aects analyzed and prin

ted ECGs.

The baseline wander lter is represented by a \W" in the

ECG report's lter box.

Note

Because of the continuous recording of the ECG in

Manual mo de, a dierent 0.5 Hz (baseline wander)

lter that may distort the ST segmentmust be used.

Therefore, do not attempt to interpret the contour

aspects of Manual ECGs at this setting. If contour

analysis is important in Manual mode, use the 0.05 Hz

Manual frequency response setting which minimizes the

ST segment distortion. Regardless of the low frequency

setting in Manual mo de, the rhythm characteristics of

the ECG are accurately recorded.

Understanding Simultaneous 12-Lead Acquisition 3-9

Artifact Filter

The Artifact lter removes skeletal muscle artifact. This

source of noise is the most dicult to eliminate because

it has the same frequencies as the ECG signals. The

Artifact lter, while eliminating skeletal muscle artifact,

also removes low amplitude, high frequency components

from the ECG.

Specically, the lter removes up to 50V of signals

in the frequency range from 5 Hz to 150 Hz which can

aect P waves as well as the entire QRS-T complex. Use

the Artifact lter only as a last resort for ECGs which

would otherwise b e unreadable due to signican

t levels

of muscle artifact. The Artifact lter only aects ECG

data on the printed ECG report and not ECG data that

is analyzed.

Monitoring ECG

Quality

The letter \F" in the far left position in the lter bo

x

indicates that the Artifact Filter was applied to this

ECG.

The HP interpretive cardiograph monitors ECG trace

quality throughout the lead attachment, ECG acquisition

and analysis process to ensure that you receive the

highest possible quality ECG trace. There are four

possible ways that trace quality problems are indicated,

depending on howyour cardiograph is equipped:

on the patient mo dule display during electro de

attachment

on the preview screen before recording the ECG

on the keyboard display during analysis

in the analysis statements on the printed report

3-10 Understanding Simultaneous 12-Lead Acquisition

In most cases, the operator can use these cardiograph

features to eliminate noise quality problems by

modifying lead placement or improving patient

preparation.

While attaching lead wires to the patient, the operator

receives constant feedback ab out leads with po or contact

and noisy lead wires on the patient module display

and/or on the preview screen. Electrodes that are o are

denoted by an \X" on the patient mo dule display,or

a straight line on the preview screen. On the patient

module, noisy lead wires are indicated with a series of

bars; the taller the bars, the noisier the signal. On

the preview screen, noisy lead wires are indicated b

poor ECG signals. With this immediate feedbac

y

k, the

operator can correct problems b efore the ECG trace is

acquired, analyzed and printed. This saves the operator

time and paper.

The real-time ECG traces in all leads can be view

the preview screen before analysis and prin

ting. Three

ed on

leads are displayed at one time and the op erator can

scroll through all congured leads in groups of three to

check the quality of the actual ECG tracings visually

.

When an Auto ECG is requested, the preview screen will

display the Auto 3x4 ECG tracing that will be analyzed

and printed. The op erator can press the

4

Stop

5

key and

correct visible noise problems.

The HP interpretive cardiograph attempts to preacquire

ECG data by immediately using the data from the most

recent ten seconds if there is good electrode contact for

all leads. Preacquisition saves operator time if go od

ECG signals are available prior to requesting the Auto

ECG.

Understanding Simultaneous 12-Lead Acquisition 3-11

During analysis, the cardiograph further checks to

determine if the trace quality is adequate for go od ECG

measurements. The ECG is analyzed for muscle artifact,

AC noise, baseline wander, and leads-o. Any noise

problems not corrected by the operator are detailed in

the interpretive statements on the ECG analysis report.

If the noise conditions are sucient to prevent ECG

analysis, the ECG will be printed without analysis. The

operator must then correct the noise problem and retake

the ECG.

On some PageWriter models, the qualitycheck presents

an advisory message on the display. If the data is

acceptable on all 12 leads, the message is

ECG ok

.

Otherwise, the types of noise and the leads or lead

groups in which the noise o ccurs are indicated. If the

noise is severe enough that analysis results could be

impaired, then

Retry

is displayed at the end of the

advisory message. At this point the op erator can press

4

5

and correct the noise problem before retaking the

Stop

ECG.

The qualit y checks available on the HP interpretive

cardiograph aid the operator in eliminating noise

problems encountered throughout the pro cess of taking

an ECG. They allow the op erator to correct noise

problems by mo difying ECG technique before the ECG

is printed. The operator can use these features to ensure

that a high quality ECG is recorded.

3-12 Understanding Simultaneous 12-Lead Acquisition

The HP ECG Analysis Program

The HP ECG Analysis Program produces precise,

accurate and consistent ECG measurements. The

program further provides interpretive statements that

highlight key areas of concern for your review. However,

this tool is more helpful if you understand how and

whyitworks and howyou can b est use its capabilities.

Figure 4-1 shows this process. (Note that Operator

Feedback and Extended Measurements report are not

available on some PageWriter models.)

ECG &

Patient

Data

HP ECG Analysis Program

4

Feedback

To

Operator

Quality

Monitor

Measurements

Figure 4-1. The HP ECG Analysis Process.

Criteria

Extended

Measurement

Matrix

The HP ECG Analysis Program 4-1

Interpretive

Report

Overreader

Understanding the

HP ECG Analysis

Program

The analysis process begins with the simultaneous

acquisition of the ECG's 12 conventional leads. It

then pro ceeds through four steps before producing the

interpreted ECG report. These steps are:

1.

Quality Monitor

{ examines the technical qualityof

each ECG lead.

2.

Pattern Recognition

{ locates and identies the

various waveform components.

3.

Measurement

{ measures each comp onent of the

waveform and performs basic rhythm analysis,

producing a comprehensive set of measurements.

4.

Interpretation

{ uses the extended measurements,

with information about the patient such as age and

sex, to select those interpretive statements from the

criteria program which summarize the ndings for the

ECG.

Hewlett-Packard provides two standard criteria

programs, adult and pediatric, for your HP interpretive

cardiograph. Future updates to these programs or

entirely new programs can b e installed easily in y

our

cardiograph, if is equipped with a exible disk.

Patient information, including age, sex, height, weight,

medications (Rx co des) and previous diagnoses (Dx

codes), are used by the criteria programs in selecting the

interpretive statements. (Rx codes and Dx codes may

not be available on some PageWriter models.)

4-2 The HP ECG Analysis Program

How the HP

Interpretive

Cardiograph

Measures ECGs

The HP interpretive cardiograph calculates

measurements for all the waveforms that you see on the

Auto 3x4 report. Every beat in every lead is measured

individually, allowing the natural variations among

beats to contribute to the representative measurements.

This is in contrast to other measurement methods in

which a representative b eat is constructed and then

measurements are made only for the constructed beat.

In the HP interpretive cardiograph, representative

group, lead and global measurements are calculated from

combinations of the comprehensive set of measurements

for each b eat. The ECG criteria program can use an

combination of these three types of measurements, which

enhances the exibility and p ower of its interpretive

capabilities.

y

Figure 4-2. ECG Morphology Measurements.

The HP ECG Analysis Program 4-3

Waveform

Recognition

The rst step of the measurement program involves

waveform recognition and beat detection. A boundary

indicator waveform in which QRS complexes and

pacemaker spikes are enhanced is derived from all

leads over the ten-second analysis perio d. After the

approximate QRS complex and pacemaker spike

locations are known, another boundary indicator

waveform that enhances P and T wave detection is

derived. Approximate P wave, QRS complex and T wave

regions are then determined for each beat in the ECG.

Comprehensive

Measurements

Group Measurements

After the approximate waveform lo cations are known,

they are further rened to determine precise onsets

and osets for eachwaveform. Once onsets and osets

are known, amplitude, duration, area and shape are

calculated for every P wave, QRS complex, T wave and

ST segmentinevery lead that you see on the Auto 3x4

report. Waveform irregularities such as notches, slurs,

delta waves and pacemaker spikes are also noted for

every beat. A table of all these measurements is created,

from which the representative measurements are

calculated.

After all the beats have b een measured, each beat in the

ECG is classied into one of verhythm groups based on

rate and morphology parameters. Each group consists

of beats with similar R-R intervals, durations, and

shapes, except that all paced beats are grouped together,

regardless of other parameters. Group 1 represents

the type of beat that is most normal or predominan

t

and groups 2 through 5 represent other beat types.

The group into which each b eat is classied is noted

under the heading \Rhythm Grouping of Beats" on the

Extended Measurements report. Group measurements

4-4 The HP ECG Analysis Program

are calculated byaveraging the measurements for all

the beats in each of the groups and are reported in the

Rhythm Analysis section of the Extended Measurements

report.

Lead Measurements

Atrial Rhythm

Analysis

Representative measurements for each of the 12 leads are

calculated from the comprehensive set of measurements

for all the beats in the ECG. Only the beats of the

predominant group (Group 1) are used. If a particular

lead (as shown on the Auto 3x4 report) do es not have

any Group 1 b eats, a beat group with similar parameters

is used, if possible. The measurement program tries

to select a beat group for whic

h the beats are not

paced. Only if all beats in the ECG are paced will the

measurements b e for paced beats. If there are paced and

non-paced beats in an ECG, only the non-paced b eats

will be measured, whichmay result in leads for whichno

measurements are rep orted.

In each lead, the measurements for all the beats

belonging to the selected beat group are a

veraged. The

lead measurements are representative of the dominant

waveform present in each lead and are reported in

the Morphology Analysis section of the Extended

Measurements rep ort.

Atrial rhythm is determined by examining leads V1,

aVF, II and II I in succession until the program can

report conclusively that there are multiple P waves, that

there are no P waves, or that there is one P waveper

QRS complex. If a conclusive result is achieved, then the

last lead analyzed will be used to calculate group and

global atrial rhythm parameters. If no conclusive result

is achieved, no atrial rhythm parameters are calculated.

The HP ECG Analysis Program 4-5

Global Measurements

The global measurements for the ECG, including

the frontal and horizontal plane axis measurements,

are reported to the right of the lead measurements

in the Morphology Analysis section of the Extended

Measurements report.

These interval, duration, and segment measurements

are weighted averages of the lead measurements. The

global rate reported is the mean ventricular rate over the

entire ECG unless the ECG criteria program determines

that one of the group mean ventricular rates is more

representative of the underlying rh

ythm.

Axis Measurements

Although it is most convenient to use waveform

amplitudes when making axis measurements manually,

using the areas of the waveforms yields more accurate

results. The HP interpretive cardiograph uses the

waveform areas from the lead measurements in

calculating the P, QRS and T axes, while the sum of

the ST onset, middle and end amplitudes is used in

calculating the ST axis. For the frontal plane axis

measurements, which use the limb leads, nine lead pairs,

all at least 60 degrees apart, are used to estimate the

axes. The resulting estimates are examined to ensure

that they converge to a single result. If so, they are

averaged to form the representative axis measurement.

The horizontal plane axis measurements, which use leads

V1{V6, are calculated similarly from seven lead pairs.

The representative measurements are rep orted on the

Extended Measurements report. A printed example

and a brief explanation of this rep ort are in Chapter

7,

Reading the Printed Rep ort

Extended Measurements Rep ort

. App endix C,

The

explains each of the

measurements on the report in more detail.

4-6 The HP ECG Analysis Program

The ECG Criteria

Language (ECL)

The ECG Criteria Language (ECL) is a

medically-oriented computer language developed

specically by Hewlett-Packard for the denition of

electrocardiographic criteria. First introduced in 1978,

the HP ECG Analysis Program, using ECL, was one of

the rst commercially-available expert systems.

The primary ob jective of ECL is to allow criteria

denition byphysicians with little or no knowledge

of computer programming. Basically, it provides a

way through which ECG criteria may be expressed in

a form that both a cardiologist and a computer can

read. Consistently-used terminology was chosen to

describe ECG criteria for the foundation of ECL. This

terminology was chosen from a broad base of users as

well as electro cardiography texts.

Categories

Sentences

At the highest level, criteria expressed in ECL are

broken into medically signicant categories that are like

the chapters of an electro cardiography textb ook.

Within each category is a series of sentences in which

the criteria are expressed. These sentences allow the

program to PRINT an interpretive statement when

the criteria are met, to SUPPRESS a statementin

the presence of a higher-priority statement, to GOTO

another point in the program, or to perform calculations

and assign (SET) the result to a variable for use later in

the program. The PRINT sentence has this form:

PRINT<interpretive statement>IF<medical criteria>;

The HP ECG Analysis Program 4-7

For example, the following statement causes an inferior

infarct statement to b e printed on the report if the

criteria are met:

PRINT #IMI10 BO

\Consider inferior infarct"

. \Small Q waves in II, III, aVF"

IF (Q:DURATION . . . ;

where IMI10 is the statement code corresponding to

the statement enclosed in quotation marks and BO

stands for a severity of borderline signicance for this

statement. In this example the interpretive statement

is \Consider inferior infarct". The reason statement,

\Small Q waves in I I, II I, aVF", summarizes the detailed

criteria which follow the IF.

Interpretive statements on the rep ort are preceded by

3

either a \.", as shown in this example, or a \$" or a \

".

Statements preceded by a \$" or a \3" call attention

to certain technical aspects of the ECG which are of

interest to the overreader, but not essential for the nal

report. These statements are automatically suppressed

by the HP 5600C ECG Management system after the

ECG rep ort has been conrmed.

A cardiologist reading an ECG can immediately

discount many classes of interpretation. However,

the computer-based program must check them all

sequentially. Within a category, the criteria for

interpretive statements become more and more

restrictive from beginning to end. Consequently, criteria

met for any given ECL statement in a category

4-8 The HP ECG Analysis Program

automatically suppress any previous statements (in that

category) that had been selected for printing. Thus, each

category can only be represented on the nal report

by one statement at most. This statement is the last

one encountered whose medical criteria were true based

on the measurements, earlier decisions, and patientID

information.

Overall Severity

Further

Information

Each statement selected for the interpretive rep ort has

an associated severity. The severities of all selected

statements are considered by a set of rules in the criteria

program to determine the ECG's overall severity. This

severity is printed on each page of the interpretive

report.

The HP 5600C ECG Management System supports

the complete developmentenvironment for ECL

programs. ECL programs modied or developed on

the ECG Management System can be used with the

HP interpretive cardiograph. For further information

about the ECL programming language, please refer

to the

Programmer's Reference Manual

Model 5600C ECG Criteria Language (ECL)

.

The HP ECG Analysis Program 4-9

The HP Adult ECG Criteria Program

Development of the Hewlett-Packard Adult ECG

Criteria Program began in 1971 as a combined eort

between Hewlett-Packard and a worldwide panel of

cardiologists. The program is written in the ECG

Criteria Language (ECL), whichwas created by

Hewlett-Packard to follow the logical pro cess used by

skilled physicians to analyze ECGs. The design of the

program and a complete developmentenvironment

allow it to b e modied easily on the HP 5600C ECG

Management System.

The adult ECG program was rst intro duced into the

clinical environment in 1978 as part of the HP 5600C

ECG Management System. It has evolved through the

years into the sophisticated program available today.

The program has also been available as part of the

Hewlett-Packard PageWriter intelligent cardiograph

family since 1983. Now in its eighth release, the

Hewlett-Packard adult ECG program has been used

worldwide to analyze an estimated 16 million ECGs

annually.

5

The HP Adult ECG Criteria Program 5-1

Understanding the

HP Adult ECG

Criteria Program

This chapter contains brief descriptions of the

ma jor categories of interpretive statements in the

Hewlett-Packard adult ECG program. Reviewing these

descriptions will help you understand the program's

breadth of scope and depth of analysis in various areas

of ECG interpretation. You will then be b etter able to

use Hewlett-Packard's computer-assisted ECG analysis

eectively in your daily ECG overreading activities.

The criteria used to select the interpretive statements

in this program use the full range of measurements in

the measurement matrix. These include durations,

amplitudes, areas, and other parameters described in

Appendix C,

The Extended Measurements Rep ort

.

For clarity and conciseness, the following summaries

are not comprehensive. Rather, when describing the

criteria logic where the signicantvalues vary, only

one measurementvalue is mentioned and it is labeled

\(typical)". The typical value is the one that is most

generally applied in the logic. You will then be better

able to use Hewlett-Packard's computer-assisted ECG

analysis eectively in your daily ECG overreading

activities.

In the criteria logic there are many situations in which

an interpretive statement that is otherwise qualied to

be printed, is suppressed by more signicant conditions

that override the initial statement. For example, left

bundle branch blo ck will prevent the printing of many

statements including all of those relating to ventricular

hypertrophy, most infarcts, T wave abnormalities, ST

deviations, etc. These suppressive conditions generally

are not addressed in the categories discussed in this

chapter.

5-2 The HP Adult ECG Criteria Program

The following categories, representing clinically

relevant statements and some technical statements and

disclaimers, are described in the following sections.

Pediatric Age Disclaimer

Calibration Notice if not Standard

Technical Quality Statements

Electronic Pacemaker

Basic Cardiac Rhythm

Premature Beats (Short R-R)

Pauses (Long R-R Interval)

Miscellaneous Arrhythmias

AV Conduction (PR Interval)

QRS Axis

Ventricular Conduction Delays

RightAtrial Enlargement

RightVentricular Hypertrophy

Left Atrial Enlargement

Left Ventricular Hypertrophy

Chronic Pulmonary Disease

Inferior Infarct

Posterior Infarct

Lateral Infarct

Anterior Septal and Anterior Infarct

Anterolateral and External Anterior MI

Apical Infarct

Tall T Waves

Drug and Electrolyte Eects

TWave Abnormalities

Ischemia

ST Segment Depression

Subendocardial Injury

Combined ST and T Abnormalities

Injury and Ischemia

ST Segment Elevation

Severity

The HP Adult ECG Criteria Program 5-3

Pediatric Age

Disclaimer

The Hewlett-Packard Adult ECG criteria program

is intended for use on ECGs of adults. The

Hewlett-Packard Pediatric ECG criteria are selected for

use on ECGs of patients under 16 years old. If adult

criteria are selected and if the patient is less than 16

years old, a statement is printed to remind you that no

attempt will be made to interpret signs of infarction or

ST{T abnormalities.

On the cardiograph, the patient's age can be entered in

units of hours, days, weeks, months, or years. It also

maybe entered as the year of birth, in whic

h case an age

in years will be calculated by the cardiograph.

Calibration Notice if

Not Standard

Calibration Nominal

Half standard 5 mm/mV 4.75{5.25 mm/mV 5%

Standard 10 mm/mV 9.5{10.5 mm/mV 5%

Double standard 20 mm/mV 19.0{21.0 mm/mV 5%

If the age is entered improp erly or not at all, the patien

is assumed to be more than 35 y

ears old.

This category checks the calibration pulse in each

channel of the ECG. Except for the case where both

the limb leads and the precordial leads are at standard

calibration (10 mm/mV), a statement describing the

calibration for the ECG is included in the report.

Table 5-1. Calibration

Value

Allowed

Range

6

%

t

5-4 The HP Adult ECG Criteria Program

Technical Quality

Statements

This category contains non-clinical statements which

are intended to identify ECGs with technical problems

and prevent them from being interpreted by the medical

criteria.

Electronic Pacemaker

Basic Cardiac Rhythm

This category relies on the ECG measurements to detect

paced ECGs. For ECGs which are predominantly-paced

there is no further consideration of medical criteria.

For demand-paced ECGs in which there are enough

non-paced beats, no further rhythm analysis is

attempted. However, the non-paced beat measurements

are used in the remaining categories to c

heck for other

abnormalities in the ECG.

One statement describing the basic cardiac rhythm is

selected from this category based on the morphology and

rhythm measurements made from the ECG.

Interpretive statements regarding the basic cardiac

rhythm are generated based on the interrelationships of

the various measurements and determinations. These

statements include those related to:

Tachycardia, bradycardia, and varying rate

Sinus, atrial, supraventricular, junctional and

ventricular rhythms

Second and third degree AV block (rst degree blockis

addressed in the AV Conduction category)

AV disso ciation

Atrial brillation

Atrial utter

Bigeminy and Trigeminy patterns

The HP Adult ECG Criteria Program 5-5

A normal P axis measurement(030 to 120 degrees

in the frontal plane) is assumed to indicate a

sinus-originated P wave while an abnormal P axis

signies an atrial or a junctional origin.

Tachycardia is generally dened as a rate of 100 b eats

per minute (bpm) or higher; bradycardia as slower than

50 bpm. For a more denitive discussion of tachycardia

and bradycardia see the recommendations of the

\Task Force on Standardization of Terminology and

Interpretation" as published in the

Cardiology

, January 1978.

American Journal of

Premature Beats

(Short R-R)

Pauses (Long R-R)

Interpretive statements in this category relate to

premature beats. These are recognized when the

preceding R-R interval is shorter than the average R-R

interval of a background ventricular rate that is basically

regular. A 15% (typical) or greater reduction in R-R

interval is considered signicant.

Premature b eats with normal QRS duration (QRSD) are

considered to be atrial or junctional in origin depending

on the presence or absence of a P w

ave. Those with

longer than normal QRSD are considered to be either

ventricular in origin or to be aberrant supraventricular in

origin.

Long R-R intervals are signicant if they are more than

140% (typical) of the average R-R in a background

ventricular rate that is basically regular. They are

considered to indicate either a sinus arrest or an

intermittentAV block. Interpretive statements in this

category indicate either escape b eats or t

ypes of second

degree AV blo ck.

5-6 The HP Adult ECG Criteria Program

The presence or absence of a P waveaswell as the

duration of the QRS indicates the origin of an escape

beat. Atrial and supraventricular escapes will showaP

wave and a normal QRSD. Junctional escape will show

no P wave, but a normal QRSD. A prolonged QRSD

indicates a ventricular origin of the escap e beat.

Dierent second degree AV blo cks are indicated on

the basis of more P waves than QRS complexes. A

statement indicating Mobitz I (Wenckebach) second

degree AV blo ck depends on progressively longer PR

intervals preceding the long R-R interval.

Miscellaneous

Arrhythmias

This category provides interpretive statements related to

arrhythmias that are not covered in the preceding Basic

Cardiac Rhythm, Premature Beats, or Pauses categories.

Statements relating to interpolated b eats depend on the

measurement program recognizing that such beats are

present. It recognizes the beats if there are consecutiv

R-R intervals that are approximately one half the

average R-R of a background ventricular rate that is

basically regular.

Aberrant complexes are recognized when the R-R

interval is only slightly decreased but the QRSD is

prolonged, as if it were of ventricular origin.

e

The HP Adult ECG Criteria Program 5-7

AV Conduction (PR

Interval)

All statements in this category are based on the

measurement of a prolonged PR interval, with the

exception of one statement which identies ECGs with

accelerated AV conduction.

The PR interval varies slightly according to age and

heart rate. The following table denes the limits:

Table 5-2.

Borderline and Abnormally Prolonged PR

Intervals (ms)

Age

(years)

0{15 200{210 190{200 185{195 180{190

16{60 210{220 200{210 195{205 190{200

over 60 220{230 210{220 205{215 200{210

Left Value = PR Interval Upper Limit (Borderline)

RightValue = PR Interval Upper Limit (1st degree AV

Block)

1{50 51{90 91{120 over 120

Heart Rate (bpm)

5-8 The HP Adult ECG Criteria Program

QRS Axis

The mean electrical vector (mean QRS axis) is

calculated in the frontal and horizontal planes. The

normal frontal axis range varies with age and body

build. The frontal QRS axis in young persons will

tend to the right. The frontal QRS axis in old persons

will tend to the left. In addition, the QRS axis in

thin persons will tend to b e more to the right than in

heavy persons. A frontal QRS axis between030 and

+90 degrees is considered normal, generally sub ject

to modication by age and build. Frontal QRS axis

measurements counterclockwise from030 will be

considered to be deviated to the left and those cloc

from +90 will be considered to be deviated to the righ

Interpretive statements based on frontal QRS axis

measurements are made describing left and right

deviation as well as sup erior, horizontal, and vertical

directions.

Statements involving p osterior axis, arm lead reversal

and dextrocardia are based on the horizontal plane axis

measurements as well as the frontal plane measurements.

These statements are skipp ed if the ECG is paced, if the

patientisinaventricular rhythm or if the mean QRS

axis is well within the normal range (30 to 80 degrees,

clockwise, in the frontal plane).

kwise

t.

The HP Adult ECG Criteria Program 5-9

Ventricular

Conduction Delays

A QRS duration (QRSD) greater than 100 ms is

common to all of the interpretations in this category

except for isolated Left Anterior Fascicular Block

(LAFB) and Left Posterior Fascicular Blo ck (LPFB)

which are present in the absence of a prolonged QRS.

Otherwise, any denitive blockinterpretation requires

that the QRSD exceed 120 ms. A QRSD between 110

and 120 ms is considered incomplete blo ck and between

100 and 110 ms is considered marginal intraventricular

conduction delay.

LAFB interpretations are asso ciated with left

ward

deviation of the mean frontal QRS axis b etween040 and

240 (typical) degrees counterclockwise.

interpretations are asso ciated with rightward deviation

of the mean frontal QRS axis b etween 120 and 210

(typical) degrees clo ckwise.

RBBB interpretations are always associated with the

terminal portion of the QRS being directed to the righ

t,

i.e. dominant negative (Q, S) forces in I, aVL, and V6

and p ositive forces in V1.

LBBB interpretations are always associated with the

terminal portion of the QRS being directed to the left,

i.e. dominant positive (R, R

0

) forces in I, aVL and V6

and negative forces (Q, S) in V1.

LAFB and LPFB may b e recognized in combination

with RBBB.

The Wol-Parkinson-White conduction abnormalityis

also recognized in this category based on the occurrence

of delta waves in multiple leads and a QRS duration

more than 100 ms. A short PR (PR segment<55 ms or

PR interval<120 ms) reduces the required number of

leads with delta waves required to detect this condition.

5-10 The HP Adult ECG Criteria Program

Right Atrial

Enlargement

Large P waves are considered suggestive of RAE. The

minimum voltage considered signicant is 0.24 mV

(typical). P wave duration and amplitude are examined

in all leads.

Larger P waves lead to more severe interpretive

statements regarding the likeliho od of RAE.

Right Ventricular

Hypertrophy

Rightventricular hypertrophy statements are made on

the basis of the presence of several ndings:

The presence of a prominen

t R or R

0

in lead V1

The presence of a prominent negative voltage in either

of leads I or V6

Right atrial enlargement

Right axis deviation in the frontal plane

ST{T changes characteristic of RVH

The statements to b e printed regarding RVH are

determined by the combinations of the above ndings.

Stronger statements result when multiple ndings are

present.

Prominent R or R0in V1

An R that is more than 75% the size of the Q or S is

signicant. An R0larger than 20 ms and 0.30 mV is

signicant. A QRS with a positive comp onent larger

than the negative comp onent (i.e., a p ositive QRS area )

is highly signicant.

The HP Adult ECG Criteria Program 5-11

Prominent Q or S in I or V6

AQ,S,orS0larger than 40 ms and 0.20 mV is

signicant. A QRS with a negative component larger

than the positive component (i.e., a negative QRS area)

is highly signicant.

Right Atrial Enlargement

This nding is determined by the presence of RAE from

the RightAtrial Enlargement category.

Right Axis Deviation in the Frontal Plane

This nding is determined by a frontal QRS axis

between 111 and 269 degrees (clo ckwise).

ST{T Changes Characteristic of RVH

This nding is determined by an examination of leads

II, aVF, V1, V2, and V3 for the presence of negative

ST and T values typical of the rightventricular strain

pattern.

Left Atrial

Enlargement

All leads are examined for the duration and the

amplitude of both the initial and terminal portions of

a biphasic P wave. Durations over 110 ms combined

with amplitudes over 0.10 mV are considered signicant

though not necessarily abnormal unless they are present

in multiple leads. A notched P wave adds to the

signicance of the other values.

Lead V1 is specically examined for duration, amplitude

and area of the negative component of the T wave.

Though durations of over 30 ms and amplitudes over

0.09 mV can be considered signicant, the area of this

negative componentmust be greater than 0.60 Ashman

5-12 The HP Adult ECG Criteria Program

units to be considered LAE. An Ashman unit is the area

of 1 square millimeter at normal speed (25 mm/sec) and

normal sensitivity (10 mm/mV). An Ashman unit equals

40 ms x 0.1 mV.

Left Ventricular

Hypertrophy

Left Ventricular Hypertrophy statements are made on

the basis of a point score derived from several ndings:

High voltage in QRS components

Left axis deviation in the frontal plane

Left atrial enlargement

ST{T changes characteristic of LVH

Prolonged QRS duration or ventricular activation time

(VAT)

Higher point scores result in more severe statements

regarding the likelihood of LVH.

High Voltage in QRS Components

Voltage values for the QRS comp onents that are

considered excessively high vary with the leads involved

and whether the deection is positive or negative. In

frontal leads the minimum value that is considered

excessive is a p ositive deection of more than 1.20 mV in

lead aVL.

Precordial leads V1 and V2 are examined for negative

deections (Q or S) and V5 and V6 are examined

for positive deections (R or R0). These values are

considered individually and anyvalue greater than

2.50 mV is considered signicant. In addition, the

negative values in V1, V2 and the positive v

alues in V5,

V6 are added together. Any total for Q or S in V1 plus

RorR0in V5 or V6 that exceeds 3.50 mV is signicant.

A total of Q or S in V2 plus R or R0in V5 or V6 must

exceed 4.0 mV to be signicant.

The HP Adult ECG Criteria Program 5-13

Higher voltages will result in more points for qualifying

statements regarding LVH.

Because higher voltages are normal for young persons,

age is given consideration in the recognition of LVH.

The younger the patient, the more stringent are the

requirements for an LVH statement.

Left Axis Deviation in the Frontal Plane

This nding is determined by a frontal QRS axis

between031 and090 in the absence of any statement

indicating either anterior fascicular blo ck or inferior

infarct.

Left Atrial Enlargement

This nding is determined by a statement from the Left

Atrial Enlargement category indicating the presence of

LAE. This feature is ignored in the presence of mitral

valvular disease, atrial utter, or atrial brillation.

ST{T Changes Characteristic of LVH

This nding is determined by an examination of leads

I, aVL, V4, V5, and V6 for the presence of negative

ST and T values typical of the left ventricular strain

pattern.

A Prolonged QRS Duration or Ventricular Activation Time

This nding is determined by a QRS duration of 95 to

120 ms, and a VAT longer than 55 ms. It is ignored if

any bundle branch block statement has b een made.

The statements to b e printed regarding LVH are

determined by the combinations of the above ndings

that are present.

5-14 The HP Adult ECG Criteria Program

Chronic Pulmonary

Disease

All frontal leads are examined for QRS peak-to-peak

voltage. If no lead has a value exceeding 0.60 mV the

ECG is considered borderline lowvoltage. If no value

exceeds 0.50 mV the ECG is considered denite low

voltage, an abnormal nding.

All precordial leads are examined for QRS peak-to-p eak

voltage. If no lead has a value exceeding 1.00 mV the

ECG is considered denite lowvoltage, an abnormal

nding.

Combinations of lowvoltage statements, and the

presence of rightward deviation of the frontal P and

QRS axes and right atrial enlargement, may lead

to statements suggesting the likeliho od of c

hronic

pulmonary disease.

Inferior Infarct

Leads II, II I. and aVF are examined for Q w

ave presence

and size (amp x dur), the relative amplitudes of the Q

and R, the presence of T wavechanges (attened or

inverted), and the presence of an elevated or depressed

ST segment.

As the Q waves become larger and/or show in more

leads, and the R waves become less prominent the

interpretive statements b ecome stronger.

For inferior Q waves to be considered signicant, at

least one of them must be longer than 25 ms in duration

and more than 1/6 the amplitude of the asso ciated R.

For any infarct statement to qualify, at least one Q

wavemust b e longer than 35 ms and more than 1/5 the

amplitude of the R wave.

The HP Adult ECG Criteria Program 5-15

A leftward direction of the axis of the initial portion

of the QRS adds to the likelihoo d of an inferior infarct

statement.

Twave and ST changes are used to estimate the age of

the infarct. Increased T waveinversion and larger ST

segment deviations will generate statements indicating

more recent infarction.

Sex and age inuence the detection of inferior infarct in

that b eing male and/or young makes normal Q waves

more likely in the inferior leads.

Posterior Infarct

Leads V1 and V2 are examined for the relative and

absolute sizes of the R and S waves, an absentor

insignicantQwave (less than 10 ms and 0.05 mV), and

a positiveTwave. A prominentR(typical is three times

the size of the S), in the presence of an insignican

tQ

(typical is<10 ms,<0.05 mV), and an uprightT,

might generate a statement suggesting the likelihoo d

of a p osterior infarct (PMI). There are no statemen

denitely indicating the presence of a PMI. In ev

ts

aluating

the signicance of the R wave, the duration is given

more emphasis than the amplitude.

Indications of LVH or RVH will decrease the likelihoo d

of a PMI statement.

Sex and age inuence the detection of a p osterior infarct

in that being male and/or young makes prominentR

waves more likely in V1 and V2.

5-16 The HP Adult ECG Criteria Program

Lateral Infarct

Leads I, aVL, V5 and V6 are examined for Q wave

presence and size (amp x dur), the relative amplitudes

of the Q and R, the presence of T wavechanges

(attened or inverted), and the presence of an elevated

or depressed ST segment.

For lateral Q waves to be considered signicant there

must b e at least one that is longer than 35 ms and more

than 0.10 mV in amplitude. In addition it must havean

amplitude that is at least 20% as large as that of the R

wave.

As the Q waves become larger and/or show in more

leads, and the R waves become less prominent, the

interpretive statements b ecome stronger.

Twave and ST changes are used to estimate the age of

the infarct. Increased T waveinversion and larger ST

segment deviations will generate statements indicating

more recent infarction.

Sex and age inuence the detection of lateral infarct in

that being male or young or both makes normal Q waves

more likely in the lateral leads.

Anteroseptal and

Anterior Infarct

Leads V1, V2, V3, and V4 are examined for Q w

ave

presence and area, the relative and absolute sizes of

the R and S, whether the QRS area is negative or

positive, the presence of T wavechanges (attened or

inverted), and the presence of an elevated or depressed

ST segment.

For anyanteroseptal or anterior Q wave to b e considered

signicant, it must be longer than 30 ms (typical) in

duration and over 0.07 mV in amplitude.

Positive ndings that o ccur in V1 and V2 will tend to

be reported as anteroseptal statements while those that

occur in V3 and V4 will tend to be rep orted as anterior

statements.

The HP Adult ECG Criteria Program 5-17

As the Q waves become larger and/or show in more

leads, and the QRS progression from negative to

positive becomes more shifted laterally, the interpretive

statements become stronger for infarction in the anterior

region.

Twave and ST changes are used to estimate the age of

the infarct. Increased T waveinversion and larger ST

segment deviations will generate statements indicating

more recent infarction.

Anterolateral and

Extensive Anterior

Infarct

Leads V3, V4, V5, and V6 are examined for Q w

ave

presence and size (amp x dur), the relative and absolute

sizes of the R and S, whether the QRS area in V3 is

negative or p ositive, the presence of T w

avechanges

(attened or inverted), and the presence of an elevated

or depressed ST segment.

For anyanterolateral Q wave to be considered signicant

it must be longer than 30 ms (typical) in duration and

over 0.07 mV in amplitude.

As the Q waves become larger and/or show in more

leads, the interpretive statements b ecome stronger for

infarction.

Positive ndings in all six precordial leads will lead

to statements describing extensiveanterior infarct

conditions.

Sex and age inuence the detection of anterolateral

infarct in that being male and/or young makes normal Q

waves more likely in the anterolateral leads.

Twave and ST changes are used to estimate the age of

the infarct. Increased T waveinversion and larger ST

segment deviations will generate statements indicating

more recent infarction.

5-18 The HP Adult ECG Criteria Program

Apical Infarct

Only one statement is contained in this category and it

indicates an apical infarct in the presence of signicant

Qwaves (>25 ms,>0.10 mV) in four of these ve

leads: I I, aVF, V4, V5, and V6.

Tall T Waves

Drug and Electrolyte

Effects

All leads are examined for the presence of positiv e T

waves with amplitudes that exceed 1.20 mV, or for

positive T waves that exceed 0.50 mV and are also more

than half the size of the peak-to-peak QRS voltage. The

presence of suchTwaves can lead to statements calling

attention to the p ossibility of metab olic, electrolyte or

ischemic abnormalities.

Measurements of QT interval as corrected for heart

rate, and measurements associated with ST segment

depression and T wavechanges are examined for values

characteristic of the eects of quinidine, procainamide,

digitalis and abnormal calcium and potassium levels.

Interpretive statements are made calling attention to the

possible correlation b etween the ndings and clinical

conditions.

The presence of an Rx code indicating use of quinidine,

procainamide or digitalis will favor interpretive

statements calling attention to the ndings compatible

with the eects of those drugs.

TWave Abnormalities

All leads are examined for T wave amplitude, the

relative amplitude of the T and the QRS, and whether

the T is negative or p ositive. The fron

tal axis of the

Twave and its relation to the frontal QRS axis is also

measured.

The HP Adult ECG Criteria Program 5-19

Reduced T wave amplitude, both absolute and relative

to the QRS, as well as negative T waves, are considered

to b e abnormal ndings. Minimal changes in one or a

few leads will lead to less severe statements. As the

changes become more prominent in magnitude and the

number of aected leads increase, the statements become

more severe.

A frontal T axis that is not b etween010 and 100

degrees or a QRS-T angle greater than 90 degrees may

result in a statement indicating nonspecic T wave

abnormalities.

ECGs of persons younger than 16 years are excluded

from the least severe statements because suchTwave

ndings can be considered normal.

Whenever possible the location of T w

will be indicated as part of the in

ave abnormalities

terpretive statements.

Though not rigidly dened, the localization will generally

t the following:

Table 5-3. T Wave Abnormality Localization

Location I II II I aVR aVL aVF V1 V2 V3 V4 V5 V6

Anterior X X X

Anterolateral X X X X X X X

Lateral X X X X

Inferior X X X

A concurrent statement regarding RVH, LVH, LBBB,

RBBB, any infarct, or any statement associated with

drug therapy or electrolyte imbalance will impact this

category by tending to suppress T wave statements. This

is more true for the less severe T wave statements than

for the more severe T wave statements.

5-20 The HP Adult ECG Criteria Program

Ischemia

This category contains statements calling attention to

the likelihood of ischemia. None of these statements

involveany new examination of measurements. All

ischemia statements in this category are determined

by the qualication of a statement or combination

of statements in the preceding category,TWave

Abnormalities. The degree of likelihood of ischemia

is based on the severity of the qualifying T wave

statements.

ST Segment

Depression

All leads are examined for negative values in the ST

segment. The values examined include the following

points in the ST segment:

The onset of the ST segment (the J point)

The p oint midwaybetween the onset and the end of

the ST segment

80 ms past the J point

The end of the ST segment (the beginning of the T

wave)

Besides negative values in the ST segment, other features

are examined:

The slop e of the ST segment in degrees

The shap e of the ST segment (straight, concaveupor

concavedown)

The smallest negative ST deection considered

signicant is 0.03 mV.

The HP Adult ECG Criteria Program 5-21

As the negativity of the ST segment increases, more

severe statements are generated. Minor depression of

the segment pro duces statements with a severitycode

of Otherwise Normal. Increasing depression pro duces

statements progressing through Borderline to Abnormal.

Whenever possible the location of ST abnormalities

will be indicated as part of the interpretive statements.

Though not rigidly dened, the localization will generally

t the following:

Table 5-4. ST Segment Depression Localization

Location I II II I aVR aVL aVF V1 V2 V3 V4 V5 V6

Anterior X X X

Anterolateral X X X X X X X X

Lateral X X X X

Inferior X X X

A concurrent statement regarding RVH, LVH, LBBB,

RBBB, any new infarct, or any statement asso ciated

with drug therapy or electrolyte imbalance will impact

this category by tending to suppress ST depression

statements. This is more true for the less severe ST

depression statements than for the more severe ones.

Subendocardial Injury

This category contains statements calling attention

to the likelihood of subendo cardial injury. None of

these statements involveany new examination of

measurements. All subendo cardial injury statements

in this category are determined by the qualication

of a statement or combination of statements in the

preceding category, ST Segment Depression. The degree

of likelihood of subendo cardial injury is based on the

severity of the qualifying ST depression statements.

5-22 The HP Adult ECG Criteria Program

Combined ST and T

Abnormalities

This category contains statements calling attention to

the presence of both ST segment and T wavechanges.

None of these statements involveany new examination

of measurements. All statements in this category

are determined by the qualication of a combination

of statements in the T Wave Abnormalities and ST

Segment Depression categories. The severity of the

statements in this category are dep endent on the severity

of the qualifying ST and T wavechanges.

Injury and Ischemia

ST Segment Elevation

This category contains statements calling attention to

the possibility of subendocardial injury and/or isc

hemia.

None of these statements involveany new examination

of measurements. All statements in this category

are determined by the qualication of a combination

of statements in the T Wave Abnormalities and ST

Segment Depression categories.

All leads are examined for positive v

alues in the ST

segment and for negative T waves. The ST segment

measurements examined include the deection at the

onset of the ST segment (the J point), and the deection

at a point 80 ms after the J poin

t. The slope of the ST

segment in degrees is also examined.

The smallest positive ST deection considered signicant

is 0.05 mV.

When ST elevation is small (0.05 mV to approximately

0.25 mV) the statements are considered of Borderline

severity while larger deections are considered to b e

Abnormal.

When inverted T waves are associated with ST elevation,

the statement will include subepicardial injury as a

possibility.

If many leads show ST elevation, the statement will

include pericarditis as a p ossibility.

The HP Adult ECG Criteria Program 5-23

Whenever possible, the location of ST elevation and

subepicardial injury will be indicated as part of the

interpretive statements. Though not rigidly dened, the

localization will generally t the following:

Table 5-5. ST Segment Elevation Localization

Location I II II I aVR aVL aVF V1 V2 V3 V4 V5 V6

Anterior X X X

Anterolateral X X X X X X X

Lateral X X X X

Inferior X X X

Severity

This is the nal category of the ECL program. The

overall severity for the entire ECG is determined based

on the severity of the statements whichhave been

selected for the report. Each statement which appears

on the ECG report carries one of the following sev

NO { Normal

ON { Otherwise Normal

BO { Borderline

AB { Abnormal

DE { Defective

NS { No Severity Assigned

The severity that is assigned to the ECG interpretive

report as a whole is generally the same as the most

severe statement in the report. The severitymaybe

advanced one level from Otherwise Normal to Borderline

or from Borderline to Abnormal if three or more

statements on the report have the lesser severity.

erities:

5-24 The HP Adult ECG Criteria Program

The HP Pediatric ECG Criteria Program

Pediatric ECG interpretation criteria are particularly

well-suited for computer-assisted analysis because of

their complex, age-dependent nature. Developmentof

the Hewlett-Packard Pediatric ECG Criteria Program

began in 1975 as a natural adjunct to the adult program.

The program is written in the ECG Criteria Language

(ECL) whichwas created by Hewlett-Packard to follow

the logical process used by skilled physicians to analyze

ECGs. The design of the program and a complete

developmentenvironment allow it to b e modied easily

on the Hewlett-Packard ECG Management System.

The pediatric ECG program was rst introduced

into the clinical environment in 1983 as part of the

Hewlett-Packard ECG Management System and the

PageWriter cardiograph.

6

The HP Pediatric ECG Criteria Program 6-1

Understanding the

H-P Pediatric ECG

Criteria Program

This chapter contains brief descriptions of the

ma jor categories of interpretive statements in the

Hewlett-Packard p ediatric ECG program. Reviewing

these descriptions will help you understand the

program's breadth of scope and depth of analysis in

various areas of ECG interpretation. You will then be

better able to use Hewlett-Packard's computer-assisted

ECG analysis eectively in your daily ECG overreading

activities.

The criteria used to select the interpretive statements

in this program use the full range of measurements in

the measurement matrix. These include durations,

amplitudes, areas, and other parameters described in

Appendix C,

The Extended Measurements Rep ort

.For

clarity and conciseness in the summaries that follow,

the detailed logic of the program will not be described.

Rather, when describing the criteria logic where the

signicantvalues vary, only one measurementvalue will

be mentioned and it will be lab eled \(typical)". The

typical value is the one that is most generally applied in

the logic.

In the criteria logic there are many situations in which

an interpretive statement that is otherwise qualied to

be printed, is suppressed by other qualifying conditions

that override the initial statement. These suppressive

conditions generally are not addressed in the categories

discussed in this chapter.

6-2 The HP Pediatric ECG Criteria Program

The following categories, representing clinically

relevant statements and some technical statements and

disclaimers, are described in the following sections.

Pediatric ECG Interpretation

Calibration Notice if not Standard

Technical Quality Statements

Electronic Pacemaker

Dextrocardia

Sinus Rhythms

Atrial Premature Complex

Ventricular Premature Complex

PR Interval

Wol-Parkinson-White Syndrome

Ventricular Conduction Delay

Right Bundle Branch Block

Left Bundle Branch Blo ck

RightAtrial Enlargement

RVH: QRS Voltage Criteria

Right Axis Deviation

RVH: T Wave Criteria

RightVentricular Hypertrophy

Left Atrial Enlargement

LVH: QRS Voltage Criteria

Left Axis Deviation

LVH: ST Segment and T Wave Criteria

Left Ventricular Hypertrophy

Biventricular Hypertrophy

Anterior ST Elevation

Inferior ST Elevation

Anterolateral ST Elevation

Anterior ST Depression

Inferior ST Depression

Anterolateral ST Depression

Anterior T Wave Changes

Inferior T Wave Changes

Anterolateral T Wave Changes

Anatomical Diagnoses

Severity

The HP Pediatric ECG Criteria Program 6-3

Pediatric ECG

Interpretation

The Hewlett-Packard Pediatric ECG criteria program is

intended for use on ECGs of children from birth to age

15. If an age is entered that is invalid, the interpretation

will be based on an assumed age of 15 years. A special

statement noting this assumption is printed instead of

the standard notice that the ECG is being interpreted

with p ediatric criteria.

The patient's age can be entered at the cardiograph in

units of hours, days, weeks, months, or years. It also

maybe entered as the year of birth, in which case an age

in years will be calculated b

y the cardiograph.

Calibration Notice if

Not Standard

Calibration Nominal

Half standard 5 mm/mV 4.75{5.25 mm/mV 5%

Standard 10 mm/mV 9.5{10.5 mm/mV 5%

Double standard 20 mm/mV 19.0{21.0 mm/mV 5%

Technical Quality

Statements

This category checks the calibration pulse in each

channel of the ECG. Except for the case where both

the limb leads and the precordial leads are at standard

calibration (10 mm/mV), a statement describing the

calibration for the ECG is included in the report.

Table 6-1. Calibration

Value

Allowed

Range

6

%

This category contains non-clinical statements which

identify ECGs with technical problems and prevent them

from b eing interpreted by the medical criteria program.

6-4 The HP Pediatric ECG Criteria Program

Electronic Pacemaker

This category relies on the ECG measurements to

detect ECGs which are paced. For ECGs which are

predominantly-paced there is no further consideration

of medical criteria. For demand-paced ECGs in which

there are enough non-paced beats, no further rhythm

analysis is attempted. However, the non-paced b eat

measurements are used in the remaining categories to

check for other abnormalities in the ECG.

Dextrocardia

Basic Cardiac Rhythm

Sinus Rhythms

Dextrocardia is suggested if the frontal P axis is between

90 and 180 degrees, and either lead I or V6 has a small

negative P wave, and b oth leads I and V6 ha

ve a large

Swave(>0.6 mV), and the P wave is larger in lead II

than in lead II I.

One statement describing the basic cardiac rhythm is

selected from this category based on the morphology and

rhythm measurements made from the ECG.

Interpretive statements regarding the basic cardiac

rhythm are generated based on the interrelationships of

the various measurements and determinations.

Sinus versus atrial rhythm statements are based on the

frontal P axis. If the P axis is bet

ween 0 and 90 degrees

the rhythm is considered to be of sinus origin. Outside

this range the rhythm is considered to be either atrial or

supraventricular.

Sinus arrhythmia is detected when there is a minor but

signicantvariation in rate within the ten second perio d

analyzed, and the P axis is normal.

The HP Pediatric ECG Criteria Program 6-5

Heart rates slower than the normal range are considered

bradycardia and those higher are considered tachycardia

as shown in the table below:

Table 6-2.

Age vs. Ventricular Rate for Sinus Rhythms

Heart Rate (bpm)

Age Range Bradycardia Normal Tachycardia

Atrial Premature

Complex

0 { 23 hours

1{7days

8 { 30 days

1{2mo.

3 { 11 mo.

1{2yr.

3{4yr.

5{7yr.

8 { 11 yr.

12 { 15 yr.



93 94{145



99 100{175



114 115{190



123 124{190



109 110{178



97 98{163



64 65{132



64 65{115



59 60{107



59 60{102



146



176



191



191



179



164



133



116



108



103

If there is a beat with essentially the same morphology

as the basic background b eat but with a rate that is

faster (thus, premature), an interpretive statementis

made for a premature atrial complex. More than one

of this type b eat within the ten seconds analyzed will

produce a statement regarding multiple premature atrial

complexes.

6-6 The HP Pediatric ECG Criteria Program

Ventricular Premature

Complex

An interpretive statement is made for premature

ventricular complex if there is a beat that has a longer

QRS duration than the background complex, has an

aberrant shape and a faster rate (thus, premature).

More than one of this type beat within the ten seconds

analyzed will produce a statement regarding multiple

premature ventricular complexes.

PR Interval

Wolff-Parkinson-White

Syndrome

Ventricular

Conduction Delay

Right Bundle Branch

Block

Upper limits for a normal PR interval vary from 130 ms

in a newborn to 180 ms in a 15 year old. PR intervals

longer than the upper limit for the patien

t's age will

produce a statement regarding prolonged PR interval for

age. However, a PR interval of 210 ms or longer will,

in all age groups, produce a statement regarding rst

degree AV blo ck.

The presence of delta waves along with a shortened

PR interval (less than 120 ms) and a QRS duration

longer than 90 ms will produce a statemen

t regarding

Wol-Parkinson-White syndrome.

A QRS duration between 100 ms and 190 ms in a

patient less than one year, or a QRS duration between

110 ms and 190 ms in a patient 1 to 15 years old will

produce a statement regarding ventricular conduction

delay for age.

The presence of a ventricular conduction delay for age

and either an RSR0or no negative component at all (no

Q or S) in V1 will produce a righ

statement. In order for the RSR

t bundle branch blo ck

0

to be signicant, the

R0must be at least 20 ms in duration and 0.15 mV in

amplitude.

The HP Pediatric ECG Criteria Program 6-7

Left Bundle Branch

Block

A statement indicating left bundle branch block will be

made in the presence of:

aventricular conduction delay for age,

a QRS axis for the terminal 40 ms between090 and

+90 degrees (clockwise),

a short (<20 ms) or absent S in I, aVL, V5, V6, and

a small or absentRwave in V1, V2, V3.

In the absence of a statement regarding LBBB, a mean

QRS axis b etween060 and090 degrees will result in a

left anterior superior fascicular block statement.

Right Atrial

Enlargement

RVH: QRS Voltage

Criteria

High amplitude P waves will pro duce a right atrial

enlargement statement. Leads I, II, I II, aVF, V1, and

V2 are examined. At least one must haveaPwave

larger than 0.25 mV in amplitude with a P w

ave larger

than 0.20 mV in another lead as conrmation.

Six dierent age groups are established with appropriate

voltage criteria for each group. A total of 24 dierent

conditions meet the criteria for the presence of adequate

RVH voltage in the varying age groups. Factors

considered in meeting these conditions are:

the absolute size of R and R0in V1 and/or V2

the absolute size of S in V6

the relative sizes of R and S in V1 and/or V6

the presence of a QR pattern in V1

This category is bypassed in the presence of any RBBB

statement.

6-8 The HP Pediatric ECG Criteria Program

Right Axis Deviation

The mean QRS axis is considered in making the

determination of right axis deviation (RAD). Three

age groups with three dierent ranges for RAD are

established as follows:

Birth to 5 days: 181 to 269 degrees clo ckwise

6days to 30 days: 161 to 269 degrees clockwise

1 month to 15 years: 135 to 269 degrees clockwise

RVH: T Wave Criteria

Right Ventricular

Hypertrophy

RVH T wave criteria are met as follows:

5days to 4 years V1 T wave amplitude>+0.10 mV,

and b oth V5 and V6 T wave

amplitude>0.01 mV, and no T

0

in

either V1, V5 or V6

5to8years V1 T wave amplitude>0.15 mV,

and b oth V5 and V6 T wave

amplitude>0.01 mV, and no T

0

in

either V1, V5 or V6

The detection of RVH is made on the basis of the

presence of qualifying statements in the RVH Voltage,

RAD, and RVH T Wave Criteria categories. Various

combinations of statements from these categories will

produce statements varying in severity from borderline

to abnormal. The likelihood of RVH increases as the

severity of the qualifying statements increases.

The HP Pediatric ECG Criteria Program 6-9

Left Atrial

Enlargement

A large negative comp onent to the P wavein V1 is

used to call attention to the likelihoo d of left atrial

enlargement. Negative P waves longer than 40 ms in

duration and larger than 0.08 mV in amplitude are

signicant when they combine to produce a negative area

of more than 4.00 ms-mV.

LVH: QRS Voltage

Criteria

Left Axis Deviation

Values considered signicantasLVH voltages are:

S amplitude more than 2.5 mV in V1

S amplitude more than 3.5 mV in V2

R amplitude more than 3.0 mV in V5

R amplitude more than 2.3 mV in V6

R amplitude more than 3.0 mV in I, II, aVL, or aVF

S amplitude more than 2.5 mV in V1

S amplitude in V1 plus R amplitude in V5 more than

4.5 mV

A combination of a 0.40 mV Q and a 1.0 mV R in

either V5 or V6

These LVH voltage criteria are used regardless of the

patient's age. This category is bypassed in the presence

of RBBB or LBBB.

The mean QRS axis is considered in making the

determination of left axis deviation. Four age groups

with dierent ranges for LAD are established as follows:

Birth to 30 days:090 to +60 degrees clockwise

1 to 2 months:090 to +40 degrees clockwise

3 to 5 months:090 to +20 degrees clockwise

6 months to 15 years:090 to 0 degrees clockwise

6-10 The HP Pediatric ECG Criteria Program

LVH: ST Segment and

TWave Criteria

Leads I, aVL, V4, V5, and V6 are examined for ST

segment and T wavechanges characteristic of LVH.

Positive ndings are of twotypes:

a mid ST segment elevation, with a large positive T

wave or:

a slight mid ST segment depression that is upsloping,

with a negative T wave.

Left Ventricular

Hypertrophy

Biventricular

Hypertrophy

Anterior ST Elevation

The determination of LVH is made on the basis of the

presence of qualifying statements in the LVH Voltage,

LAD, and LVH ST Segment and T Wave Criteria

categories. Various combinations of statements from

these categories will produce statements of varying

severity and certainty regarding the presence of LVH.

Associated RVH should be considered when anyLVH

statement is combined with a large R (>1.0 mV) in V1.

Similarly, associated LVH should b e considered when

RVH statements are combined with both a signicantQ

wave(>10 ms and>0.07 mV) and a large R wave

(>1.0 mV) in V6. Biventricular hypertrophy should

also be considered when the combined amplitudes of R

and S exceed 6.0 mV in two of leads V2, V3, or V4.

Leads V2, V3, V4, and V5 are examined for ST

elevation. ST elevation of more than 0.15 mV in

these leads produces a statement suggesting a normal

variation.

The HP Pediatric ECG Criteria Program 6-11

Inferior ST Elevation

Leads I I, II I, and aVF are examined for ST elevation.

ST elevation of more than 0.15 mV in these leads

produces a statement suggesting nonspecic ST changes

that are probably normal.

Anterolateral ST

Elevation

Anterior ST

Depression

Inferior ST

Depression

Anterolateral ST

Depression

Leads I, aVL, V2, V3, V4, V5, and V6 are examined

for ST elevation. ST elevation of more than 0.15 mV

in these leads produces one of two statements. One

suggests normal variation; the other is of borderline

severity and suggests probable asso ciation of ST changes

with LVH.

Leads V2, V3, V4 and V5 are examined for ST

depression. ST depression of more than 0.20 mV in

these leads produces a statement suggesting possible

subendocardial injury.

Leads I I, II I, and aVF are examined for ST depression.

ST depression of more than 0.20 mV in these leads

produces a statement suggesting possible subendo cardial

injury.

Leads I, aVL, V2, V3, V4, V5, and V6 are examined for

ST depression. ST depression of more than 0.20 mV

in these leads produces one of two statements, eachof

borderline severity. One suggests p ossible subendocardial

injury; the other is in asso ciation with LVH and suggests

that the ST changes are probably secondary to LVH.

6-12 The HP Pediatric ECG Criteria Program

Anterior T Wave

Changes

Leads V1, V2, V3, V4, and V5 are examined for negative

Twaves. As negative values increase from 0.01 mV

to more than 1.0 mV, the statements change from

\nonspecic" T wavechanges with a severity of Normal,

to \anterior ischemia" with a severity of Borderline.

Inferior T Wave

Changes

Anterolateral T Wave

Changes

Leads II, II I, and aVF are examined for negative

Twavevalues. As negative values increase from

0.10 mV to more than 1.0 mV, the statements change

from \Nonspecic T wavechanges" with a severity

of Borderline, to \Consider Inferior Isc

severity of Abnormal.

Leads I, aVL, V2, V3, V4, V5, and V6 are examined

for T wavevalues. Positivevalues more than 1.0 mV

indicate a probably normal T wavevariant. Negative

values call attention to the p ossibility of ischemia, with

increasing severity codes as the negative values increase

from 0.01 mV to more than 1.0 mV. Statemen

from those referring to \Nonspecic T w

with a severity of Borderline to \Consider Anterolateral

Ischemia" with a severity of Abnormal.

hemia" with a

ts range

avechanges"

The HP Pediatric ECG Criteria Program 6-13

Anatomical

Diagnoses

The likeliho od of various congenital cardiac conditions

is suggested on the basis of varying combinations of

atrial enlargement, ventricular hypertrophy, conduction

patterns, axis determinations, and QRS morphological

features.

Severity

This is the nal module of the ECL program where

the overall severity for the entire ECG is determined

based on the severity of the statements whichhave been

selected for the report. Each statement which appears

on the ECG report carries one of the following severities:

NO { Normal

ON { Otherwise Normal

BO { Borderline

AB { Abnormal

DE { Defective

NS { No severity assigned

The severity that is assigned to the ECG interpretive

report as a whole is generally the same as the most

severe statement in the report. The severitymaybe

advanced one level from Otherwise Normal to Borderline

or from Borderline to Abnormal if three or more

statements on the report have the lesser severity.

6-14 The HP Pediatric ECG Criteria Program

Reading the Printed Report

This chapter describ es the printed reports produced on

the HP interpretive cardiograph. There are three types

of clinical reports that the cardiograph can print:

7

Interpretive Report

information, a ten-second ECG waveform, and a set

of standard waveform measurements and interpretive

statements.

Extended Measurements Rep ort

on some models, shows all the waveform measurements

the HP interpretive cardiograph makes on an ECG,

including morphology and rhythm measurements. These

measurements are used to generate the interpretive

statements printed on the Auto report.

Manual Rep ort

also print a continuous ECG waveform in a variety of

formats.

This report can include patient

This report, available

The HP interpretive cardiograph can

Reading the Printed Report 7-1

Auto Interpretive

Reports

Insert artwork here.

Interpretive reports show up to six blocks of information,

as shown below. The operator can congure the HP

interpretive cardiograph so it do es not prompt for

(and therefore does not print) any patient information

except patient ID. The op erator can also congure the

cardiograph to include or omit various combinations of

the basic measurements, the interpretive statements and

the reasons statements. Note that your PageWriter may

or may not have all of these capabilities.

Figure 7-1. A Typical Interpretive Report.

A. Patient ID Information

B. Basic Measurements

C. Interpretive Information

D. Calibration Pulse

E. Rhythm Strip

F. Settings

7-2 Reading the Printed Report

Patient Information

This information is entered (or updated) by the

technician when the ECG is taken. A complete listing

of patient information codes is listed in App endix B,

PatientIDCodeTables.

Some patient information app ears to the right of the

interpretive information. This information can be

changed when conguring the cardiograph. It includes

the following information:

User A Label Lab el such as \Smoker?" or \Temp?"

that appears in ID entry process.

Limited to eightcharacters.

User B Label Label such as \Smoker?" or \Temp?"

that appears in ID entry process.

Limited to eightcharacters.

Requested by This eld displays the name of the

physician who requested the report.

Limited to 16 characters.

Edited This memo prints if the patientID

information has been edited since it was

rst entered.

Reading the Printed Report 7-3

Basic Measurements

This block gives standard interval and duration

measurements in milliseconds, and limb lead axis

measurements in degrees. These are representative

values for the dominant beat pattern in the ECG. For

more information on how representative measurements

are derived, refer to \How the HP Interpretive

Cardiograph Measures ECGs" in Chapter 4.

Table 7-1. Basic Measurements

Item Description Units

RATE Heart rate beats per

minute

PR PR interval milliseconds

QRSD QRS duration milliseconds

QT QT interval milliseconds

QTc QT interval corrected for rate milliseconds

P Frontal P axis degrees

QRS Frontal mean QRS axis degrees

T Frontal T axis degrees

7-4 Reading the Printed Report

Interpretive

Information

This block contains:

The interpretive statements whichmaybe

accompanied by,

\Reasons" statements summarizing the conditions that

produced eachinterpretive statement.

This block can also include the following types of

technical information:

Calibration statements

indicating the scaling of the

ECG trace. For example:

All leads HALF standard calibration.

All channels = 5 mm/mV.

Quality statements

indicating signal problems that

occurred during the recording. For example:

Artifact in lead(s) I III aVL

Severity statement

indicating the ECG's classication.

The severity that is assigned to the ECG interpretive

report is generally the same as the most sev

statement in the report. This is alwa

ys the last

ere

statement in this blo ck. The Criteria dene ve

severity levels. In order of severity, they are:

Normal ECG

Otherwise Normal ECG

Borderline ECG

Abnormal ECG

Defective ECG

Reading the Printed Report 7-5

Calibration Pulse

This is the rectangular waveform shown in each line

of ECG trace. It shows howmuch the cardiograph

deected the trace in response to a 1 mV calibration

pulse applied to the acquisition circuitry.

The shap e of the calibration pulse reects the scaling

of the trace. (Set with the

4

ECG Size

5

or the

4F55

keys

depending on your cardiograph.). If the calibration pulse

is square, the chest leads and limb leads were recorded at

the same scale. If the calibration pulse is stepped, the

cardiograph recorded the chest leads at half the scale

of the limb leads. The follo

wing table shows how the

calibration pulse indicates ECG sensitivity.

Table 7-2. Calibration Signals

V Leads/ECG Size

ECG Size

Full Half

mm/mV

5

10

20

Rhythm Strip

The HP interpretive cardiograph can print ten seconds

of one lead or of three leads at the bottom of the Auto

report. This additional trace is a rhythm strip. Rhythm

strips show the same ten seconds of ECG data as in the

Auto report.

7-6 Reading the Printed Report

Settings

Information about the settings at which the ECG was

taken is listed at the bottom of the Auto rep ort. Note

that your PageWriter cardiograph may not have all these

settings available.

LOC

Speed:

Limb:

Chest:

Filter box

Faulty Electrode

HP708

This label includes a lo cation co de

and a cart number.

Indicates the speed at which the

ECG was printed. Auto reports

can be printed at 25 mm/sec or

50 mm/sec.

Limb lead sensitivity setting. Can be

5, 10, or 20 mm/mV.

Chest lead sensitivity setting. Can

be 2.5, 5, 10, or 20 mm/mV.

Indicates which lters were active

when the ECG was recorded.

F

Artifact lter.

W

Baseline wander lter.

60

0.5{40 Hz

AC lter

Auto frequency lters

Leads o indication.

This is the measurements program

(7) and criteria (08) versions used by

the cardiograph.

00016

This is the sequence number, which

indicates the number of ECGs taken

as of the current rep ort since the

software was last installed.

Reading the Printed Report 7-7

Auto Report Formats

Insert artwork here.

The ECG trace can be printed in any of the following

formats.

Figure 7-2. An Auto 3x4 Report. (3x4)

Insert artwork here.

Figure 7-3. An Auto 3x4 Report with a Rhythm Strip. (3x4, 1R)

7-8 Reading the Printed Report

Insert artwork here.

Figure 7-4. An Auto 3x4 Report with 3 Rhythm Strips. (3x4, 3R)

Insert artwork here.

Figure 7-5. An Auto 6x2 Report. (6x2)

Reading the Printed Report 7-9

Extended

Measurements

Report

Insert artwork here.

The Extended Measurements report gives a complete

listing of the measurements the cardiograph made to

derive the interpretation of an ECG. This report is

especially useful if you want to examine the logic of the

given interpretation. Refer to your cardiograph's

Reference Guide

Note that your PageWriter cardiograph may not have

this capabilit y.

An explanation of each eld of the report is in Appendix

C,

The Extended Measurements Report.

for information on printing this rep ort.

User's

Figure 7-6. An Extended Measurements Report (Morphology).

7-10 Reading the Printed Report

Insert artwork here.

Figure 7-7. An Extended Measurements Report (Rhythm).

Manual Reports

When the operator starts a Manual report, the HP

interpretive cardiograph prints the ECG until the

operator stops the recording.

Manual reports show up to three types of information:

Patient information

ECG trace

Settings information

Reading the Printed Report 7-11

Manual ECGs include the same patient information as

on Auto ECGs. This information appears ab ove the

waveform. Manual reports are not analyzed, so they do

not provide measurement information or interpretive

statements. The calibration pulse appears at the

beginning of the ECG trace.

Cardiograph Settings

The cardiograph settings appear ab ove the waveforms on

Manual reports. Note that your PageWriter cardiograph

may not have all these settings available.

LOC

This lab el is at the bottom of the

Manual report page. It includes the

location code and cart number.

Speed:

Indicates the sp eed at which the

ECG was printed. Manual reports

can be printed at 5, 10, 25, or 50

mm/sec.

Limb:

Limb lead sensitivity. Can b e 5, 10,

or 20 mm/mV.

Chest:

Chest lead sensitivity. Can be 2.5, 5,

10, or 20 mm/mV.

Filter box

Indicates which lters were active

when the ECG was recorded.

F

Artifact lter.

W

Baseline wander lter.

60

AC lter

Faulty Electro de

00019

7-12 Reading the Printed Report

0.5{40 Hz

Manual frequency lters

Leads o indication.

This is the sequence number, which

indicates the number of ECGs taken

as of the current report since the

software was last installed.

Manual Report

Formats

Insert artwork here.

Manual reports can haveany combination of three, six,

or 12 leads. These Manual report formats are shown in

the following gures:

Figure 7-8. A Manual 3-Lead Format.

Reading the Printed Report 7-13

Insert artwork here.

Insert artwork here.

Figure 7-9. A Manual 6-Lead Format.

Figure 7-10. A Manual 12-Lead Format.

7-14 Reading the Printed Report

Managing Your ECGs

Besides producing lo cal hardcopy reports, many

HP interpretive cardiographs can be linked to

Hewlett-Packard ECG Management Systems. On some

PageWriter models, ECGs may b e stored to exible

disk for permanent archival, storage or transmission.

You maywant to send your ECGs to another site for

clinical review, long-term storage and retrieval, or for

management. Figure 8-1 shows the ECG management

process. (Note that Operator Feedback is not available

on some PageWriter models.)

The method of transfer can vary, depending on your

requirements and the capabilities of your cardiograph:

8

storage on exible disk: can be used b

interpretive cardiograph for subsequent retrieval and

for batch ECG transmission

local transmission through direct connect cable.

remote transmission via telephone mo dem.

ECGs can be received byany of Hewlett-Packard's ECG

Management Systems and WorkStations, or by some

models of HP interpretive cardiographs. ECGs stored to

exible disk by non-interpretive PageWriter cardiographs

can both be analyzed and transmitted in batc

disk-equipped HP interpretive cardiograph.

Managing Your ECGs 8-1

y the HP

hbya

ECG &

Patient

Data

Feedback

To

Operator

ECG Reports To

Cart Printer

Quality

Monitor

Measurements

HP ECG Analysis Program

Criteria

Serial Comparison

Previous

ECG Report

For Serial

Comparison

Cardiologist

Editing

Previous ECG

Report Dispatcher

Reports

To

Extended

Measurement

Matrix

Conrmed

Diagnostic

Report

Active

Patient

Files

Hospital

Wards

Physicians

Oces

Figure 8-1. Managing ECGs.

Unconrmed Report

and Trace, Previous

ECGS

Permanent

Patient Files

On Line

Remote

Hospitals

Other

Subscribers

8-2 Managing Your ECGs

PageWriter

Communications

ManyHPinterpretive cardiographs incorp orate a digital

transmission scheme to provide exibility and guarantee

error-free ECG transmission. ECG storage space and

telephone connect time are minimized by the use of

non-distorting compression algorithms.

An important part of the transmission proto col is its

error detection and handling capabilities. The lower level

of the protocol packages each block of data with CRC

(cyclic redundancy check) codes, and any detected error

results in retransmission of data. If a block cannot be

transmitted without error after numerous attempts have

been made, the link is terminated and the operator is

notied.

The upper level of the proto col supports an expandable

command interpreter that allows the transmission of

ECGs, analysis reports and measurement matrices from

cardiograph to cardiograph, cardiograph to an ECG

Management System, and ECG Management System to

a cardiograph. For example, following ECG transmission

from the patient's b edside, a physician can receive

a previous ECG from the system for an immediate

comparison.

Managing Your ECGs 8-3

ECG Management

Systems

When an ECG is received and stored bya

Hewlett-Packard ECG Management System several

functions can be initiated.

reports can be automatically generated. When, where,

and in which format are all under your control.

a previous ECG (or ECGs) can be retrieved and

appended to the current report for immediate review.

ECGs can be edited. Using Hewlett-Packard's ECL

statement library or using free-form text, the ECG can

be mo died with overreading comments.

Automatic dispatch. The nal rep ort, with any

necessary comments or corrections can be returned to

its originating location, and/or to other sites sharing

the ECG Management Network.

ECGs can be archived for long-term storage. The

system can archive many thousands of ECGs,

automating a very lab or intensive process.

ECGs can be used for clinical research.

8-4 Managing Your ECGs

Clinical Rewards

On a practical level, ECG management will assist

the cardiologist or physician in the recovery of ECG

information. Those who use ECG Management systems

have found that automating their ECG ling system

signicantly reduces the number of misplaced ECGs.

This, combined with the greater speed and consistency

associated with computerized record management, has

resulted in a 3% to 15% improvement in recaptured

billings for these institutions.

Automated ECG departments can further help the

cardiologist when overreading ECGs. Our experience has

shown that a doctor can overread up to three times more

quickly with computerization. Ultimately this means

more time with the patient.

There are benets to be gained in the areas of clinical

research. Having thousands of ECGs on line and

available for study on very specic parameters (How

many male patients over 60 years have rst degree

AV block?) enables drug trials, therapeutic care and

teaching improvements to be realized very easily. Sucha

statistically signicant p opulation has encouraged many

of the largest drug companies in the world to employ

Hewlett-Packard systems in their research. Most of the

information that appears on the nal rep ort ma

as a search eld. Furthermore, searches may b e made

on search result les, thus allowing multiple detailed

secondary levels of examination.

y be used

Managing Your ECGs 8-5

Current Trends

Worldwide, health-care facilities are under mounting

governmental pressure to reduce costs and manage

themselves more eciently.Aswould be expected, they

are relying heavily on information systems to assist them

in this challenge. In the cardiology department, sta

productivity related to the management and storage

of test data from high-volume tasks such as ECG

processing are especially improved.

Networking these products oers a unique solution

to the institution lo oking to manage their expanding

ECG volume eectively, and to respond to the

overreading demands of smaller surrounding institutions.

Transaction logging prevents loss of ECGs.

Previously, the high cost of large centralized ECG

Management systems limited them to only the

largest hospitals. However, the decreasing cost of

technology will now allowvendors to oer solutions to

all institutions, regardless of size. As these solutions

develop, Hewlett-Packard customers can continue to

expect a high standard of compatibility. This means that

the manyyears of ECGs stored on your current system

will not b e lost in a transition to our next generation

products.

8-6 Managing Your ECGs