ISO/TS 22077-4:2019

TECHNICAL ISO/TS
SPECIFICATION 22077-4
First edition
2019-10
Health informatics — Medical
waveform format —
Part 4:
Stress test electrocardiography
Reference number
©
ISO 2019
© ISO 2019
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ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviations . 1
3.1 Terms and definitions . 1
3.2 Symbols and abbreviated terms. 2
4 Outline of stress test cardiography rules . 2
4.1 Configuration of waveform data (see Figure 1) . 2
4.2 Time synchronization (see Figure 2) . 4
5 Waveform encoding . 5
5.1 General . 5
5.1.1 Full disclosure waveform (see Figure 3) . 5
5.1.2 Intermittent record waveform (see Figure 4) . 5
5.1.3 Abstract waveform (see Figure 5). 6
5.2 Waveform class . 7
5.2.1 General. 7
5.2.2 Waveform class for stress test electrocardiography . 8
5.2.3 Waveform class for full disclosure waveform . 8
5.2.4 Waveform class for intermittent recorded waveform . 8
5.2.5 Waveform type for abstract waveform . 8
5.3 Lead name (Waveform attributes) . 9
5.4 Sampling attributes .10
5.5 Frame attributes .10
5.6 Pointer .10
5.7 Filter information .11
6 Load information .11
6.1 General .11
6.2 Loading related events .11
6.3 Amount of load .13
7 Measurement information .14
7.1 General .14
7.2 Examination date/time .14
7.3 Rating of perceived exertion .15
7.4 R wave position .16
7.5 Interpretation and beat annotation .17
7.6 ST segment recognition points.17
7.7 ST segment measurement value .18
7.8 Other measurement value .18
Annex A (informative) Encoding of ST segment recognition point and measurement value .19
Annex B (informative) Encoding measurement value and interpretation .21
Annex C (informative) Example of waveform coding.23
Bibliography .30
Foreword
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
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described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
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.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 215, Health informatics.
A list of all parts in the ISO 22077 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved

Introduction
0.1  General
Stress test electrocardiography is an examination that is frequently used. It is used to check the changes
in biological phenomena such as electrocardiogram or blood pressure that occur during cardiac stress.
Cardiac stress can be seen via exercise or by intravenous pharmacological stimulation. The purpose of
this examination is to find cardiac abnormalities, such as myocardial ischemia disease or arrhythmia
during exertion, and to check the athletic capability of the cardiopulmonary function.
This document defines the detailed rules of stress test electrocardiogram waveform format that is
encoded according to the Medical waveform Format Encoding Rules (MFER). In addition to basic rules
defined in ISO 22077-1, there are rules for ECG waveforms electrocardiography (12lead ECG, etc.) and
long-term electrocardiography (Holter ECG) that are contained in other MFER technical specifications,
i.e. ISO/TS 22077-2 and ISO/TS 22077-3. Please refer to those specifications for additional information.
0.2  Information package added to the electrocardiogram
The stress test checks the changes in the electrocardiogram during exercise against the resting
electrocardiogram. To correctly interpret the changes, we also need to capture other waveforms such
as the blood pressure, respiration gas, SpO and the load information. These should be put into a single
package to be delivered to a third party such as a healthcare provider.
The purpose of this document is to describe waveforms of different nature in the package and how they
can be synchronized in order to be interpreted simultaneously by the recipient of the package.
0.3 About electrocardiography waveform encoding in MFER
It is recommended to store the original waveforms as much as possible, i.e. waveforms are not
irreversible compressed or filtered. This is to avoid losing the information contained in the original
waveform when reusing the waveform in research, etc. It is desirable to perform the processing
(e.g., Synthesized lead or filtering) needed for encoded waveforms. The configuration and condition
of an electrocardiogram recording may be encoded with waveform data to assure reproduction of
electrocardiographic representation when using a system such as electronic medical records. However,
it is entrusted to the system whether those can or cannot be reproduced using this information. There
are often large drift noises and EMGs on electrocardiograms during exercise stress tests. Some devices
perform special signal processing to remove these noises. And the system might not be able to perform
the same signal processing to reproduce the electrocardiogram that was recorded. In such a case, in
addition to the original waveform, storing the waveform after signal processing is also an option.
TECHNICAL SPECIFICATION ISO/TS 22077-4:2019(E)
Health informatics — Medical waveform format —
Part 4:
Stress test electrocardiography
1 Scope
This document defines the application of Medical waveform Format Encoding Rules (MFER) to
describe stress test electrocardiography, which is one of the outputs of exercise, pharmacological and
cardiopulmonary stress test. MFER performed in physiological laboratories, healthcare clinics, etc.
This document covers not only the electrocardiogram waveform but also the description of related
stress information and biological signals, e.g. blood pressure, respiration gas, SpO , etc.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO/TS 22077-2, Health informatics — Medical waveform format — Part 2: Electrocardiography
ISO/TS 22077-3, Health informatics — Medical waveform format — Part 3: Long term electrocardiography
3 Terms, definitions, symbols and abbreviations
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1.1
abstract waveform
single beat ECG waveform which is extracted from all ECG waveform during examination period,
including the waveform which did the signal processing such as averaging
3.1.2
intermittent recording
recording electrocardiogram for a given period of time at a preset interval of time
3.1.3
full disclosure waveform
electrocardiographic waveform covering the entire time from the resting period (3.1.4) to the recovery
period (3.1.7) during cardiac stress test
3.1.4
resting period
phase before loading of stress (by exercise or medication) to the patient’s heart
3.1.5
warm-up period
practise stage just before the start loading
3.1.6
loading period
phase immediately after the start loading with stress (by exercise or medication) to the patient’s heart
3.1.7
recovery period
end of loading with stress (by exercise or medication) to the patient’s heart
3.1.8
exercise stress test
examination procedure loaded to the heart to enable diagnosis of cardiac disease by exercise
Note 1 to entry: Ergometer and treadmill are representative methods for exercise stress loading.
3.1.9
pharmacological stress test
medication administered as a stress to the heart to enable diagnosis of heart disease
3.1.10
cardiopulmonary stress test
exercise stress test (3.1.8) to evaluate exercise capacity and predict outcome in patients with heart
failure and other cardiac conditions
3.1.11
borg scale
index used to express the exercise strength and to indicate the rating of perceived exertion
Note 1 to entry: The borg scale is generally used in exercise stress test.
3.2 Symbols and abbreviated terms
ECG Electrocardiogram
MFER Medical waveform Format Encoding Rules
SCP-ECG Standard Communications Protocol for Computerized Electrocardiography
SpO Saturation of Peripheral Oxygen
oxygen consumption

VO
carbon dioxide output

VCO
minute ventilation

V
E
4 Outline of stress test cardiography rules
4.1 Configuration of waveform data (see Figure 1)
Medical waveform data described in accordance with the MFER is an aggregate of waveform frame
data that consists of a header section (encoding detailed information about the waveform) and a
waveform data section (main data of waveform). The header and waveform data are encoded based
on the encoding rules which are composed of TLV (Tag - Data length - Value). One MFER waveform file
can include several waveforms. The definition of the MFER waveform file is sequentially interpreted
2 © ISO 2019 – All rights reserved

from the beginning of the file. As most definitions, multiple use is possible. The definition is used until
another definition for the same tag is encountered. Then the new definition replaces the older definition.
When there are several waveforms in a MFER waveform file, each waveform may be located anywhere
in the file. However, in the specification of stress test electrocardiography, waveform should be located
as follows for usability and to avoid erroneous interpretation.
— The information about stress test should be described before description of waveform. And the
value of waveform class definition (MWF_WFM) for the information should be ECG_EXER (stress
test ECG).
— The same type waveforms should be described in a mass and that should be located chronological.
Key
a. stress test information 1 tag
b. waveform (type #1) 2 length
c. waveform (type #2) 3 value
d. explanation about stress test 4 tag: MWF_WFM(8)
e. explanation (waveform class) 5 length: 2
f. waveform #1 of type #1 6 value: ECG_EXCER(4)
g. waveform #2 of type #1 7 tag: MWF_WAV(30)
h. frame #1 of waveform #1
i. frame #2 of waveform #1
j. header
k. waveform data
l. explanation about frame
Figure 1 — Configuration of waveform data
4.2 Time synchronization (see Figure 2)
In the data of stress test electrocardiography, several types of electrocardiogram and biomedical data,
such as blood pressure, are described together. In addition, it is necessary to grasp the state of the load
at the time the data was acquired.
The reference time of description starts counting from examination beginning. The provider shall
describe the acquisition time which is defined using the reference time for each data. The user can get
the synchronization between data by collating the acquisition time for each data.
The reference time of waveform such as electrocardiogram is described using the pointer tag (MWF_
PNT). The reference time of events such as load information (loading period, recovery period, stage
period, etc.) is described using "starting time" item of the event tag (MWF_EVT). The reference time of
measurements such as blood pressure and the amount of load such as treadmill speed are described
using the "time point" item of the value tag (MWF_VAL). The reference time is indicated as a data pointer
which depend on the sampling rate of the frame. The user may get the synchronization using pointer of
different sampling rate.
For example, if the sampling interval of load information event is 1 second (s) and the sampling interval
of ECG waveform is 2 ms, then the point of load information event becomes 60 and the point of ECG
waveform becomes 30 000 at the time of the start of the load.
Key
1 load information
tag: MWF_EVT
code:
starting time: 60 s
2 60 s
3 start of examination
4 start of load
Figure 2 — Time synchronization
4 © ISO 2019 – All rights reserved

5 Waveform encoding
5.1 General
This set of rules is aimed at ensuring that the waveforms collected serially during stress test
electrocardiography are encoded together with the information of the stress test. The waveforms
involved in stress test electrocardiography include “full disclosure waveform” (waveform in all
segments during the test), “intermittent record waveform” (waveform records in some short segments
during the test) and “abstract waveform” (waveform for a single heart beat extracted periodically
during the test).
5.1.1 Full disclosure waveform (see Figure 3)
This form is used when encoding all waveforms of electrocardiogram, etc., covering the resting
period (pre-loading), the loading period and the recovery period (post-loading). This includes not only
encoding of waveforms of all leads used in the test but also encoding of only the waveform for selected
one or multiple leads. It is a simpler description of full disclosure waveform to encode the waveform of
the entire period of the examination within one frame.
Encoding of full disclosure waveform shall be done in accordance with ISO/TS 22077-3. The waveform
class of this waveform is ECG_LTERM (2).
Figure 3 — Full disclosure waveform
5.1.2 Intermittent record waveform (see Figure 4)
This form is used when encoding the waveforms of electrocardiogram, etc., using the interval records at
the resting, the loading and the recovery periods or one-shot records taken at random during the test.
Encoding of intermittent record waveform shall be done in accordance with ISO/TS 22077-2. The
waveform class of this waveform is ECG_STD12 (1), ECG_SURF (6) or ECG_DRV (12), etc.
The point of time when the record concerned was taken during the test is encoded with using the
pointer tag (MWF PNT).
Key
1 60 s after examination starting
2 120 s after examination starting
3 sampling interval: 2 ms
4 start of examination
Figure 4 — Intermittent record waveform
5.1.3 Abstract waveform (see Figure 5)
This form is used when encoding a group of electrocardiograms for individual heart beats extracted
at the resting, the loading and the recovery periods to evaluate changes in the characteristics of
electrocardiogram waveforms during the test.
The abstract waveform includes not only the extracted waveform which is one beat during a certain
period but also the average waveform which averaged several beats during a certain period. In addition,
it includes a derived waveform which is made by a special signal processing. Encoding of an abstract
waveform is done in accordance with ISO/TS 22077-2. The waveform class of this waveform is ECG_
BAET (9).
The abstract waveforms at the same time are encoded as one frame, and there are frames of abstract
waveforms which are extracted each time. The pointer tag (MWF_PNT) of frame indicates the time of
an abstract waveform.
6 © ISO 2019 – All rights reserved

Key
1 sampling interval: 2 ms
2 start of examination
3 start of load (resting)
4 3 min after load
5 end of load (post exercise)
Figure 5 — Abstract waveform
5.2 Waveform class
5.2.1 General
The waveform class indicates that this waveform data is as stress test ECG. Furthermore, the waveform
class indicates the kind of waveform that included in this data. The format is given in Table 1.
Table 1 — Waveform class
MWF_WFM Data length Default Remarks Duplicated definitions
2 Non-specific waveform Override
08 08h
Str ≤ 32 Waveform description Override
5.2.2 Waveform class for stress test electrocardiography
A description of waveform class for stress test ECG shall be provided in the data. This description shall
precede the description of the waveform class of the waveforms included in this data.
The type for this waveform is designated in Table 2.
Table 2 — Stress test ECG waveform
Classification Type Value Waveform description Remarks
Exercise stress test ECG
Pharmacological stress test ECG
Electrocardiogram ECG_EXCER 4 Stress test ECG
Cardiopulmonary stress test
ECG
5.2.3 Waveform class for full disclosure waveform
The waveform class for full disclosure waveform is "Long term ECG". Long term ECG waveform should
be encoded in accordance with ISO/TS 22077-3.
The type for this waveform is designated in Table 3.
Table 3 — Full disclosure waveform
Classification Type Value Waveform description Remarks
Electrocardiogram ECG_LTERM 2 Long term ECG Full disclosure ECG
5.2.4 Waveform class for intermittent recorded waveform
The waveform class for intermittent record waveform is "Standard 12lead ECG", etc. This waveform
should be encoded in accordance with ISO/TS 22077-2.
The type for this waveform is designated in Table 4.
Table 4 — Intermittent record waveform
Classification Type Value Waveform description Remarks
Standard 12lead ECG including
ECG_STD12 1 Standard 12lead ECG general ECG in short term
recording.
Electrocardiogram Frank’s lead, chest bipolar lead,
ECG_SURF 6 Body surface ECG
Nehb lead, etc.
Derived ECG from Frank vector
ECG_DRV 12 Derived lead
leads, EASI lead, etc.
5.2.5 Waveform type for abstract waveform
The waveform class for abstract waveform is "QRS beat". This waveform should be encoded in
accordance with ISO/TS 22077-2.
The type for this waveform is designated in Table 5.
8 © ISO 2019 – All rights reserved

Table 5 — Abstract waveform
Classification Type Value Waveform description Remarks
One heart beat waveform which
the abstraction is made periodi-
Electrocardiogram ECG_BEAT 9 QRS beat
cally during the examination.
Average, median, dominant, etc.
5.3 Lead name (Waveform attributes)
Lead name means the waveform code that is one of waveform attributes. The format is as Table 6.
Table 6 — Definition of waveform attributes
Data Duplicated
MWF_LDN Default Remarks
length definitions
Data length = 2,
Waveform code 2 Override
if waveform information is
09 09h undefined
encoded
Waveform
Str ≤ 32 — Override
information
This is the waveform code used in stress test ECG. As the lead code is encoded by the number 0-127,
extra attention would be required in the case of conforming with other rules such as SCP-ECG.
Table 7 — Lead name 1
Code Lead Code Lead Code Lead Code Lead
0 Config 32 CB4 64 aVF 97 —
b
1 I 33 CB5 65 (-aVR) 98 —
2 II 34 CB6 66 V8 98 —
3 V1 35 — 67 V9 99 —
4 V2 36 — 68 V8R 100 —
5 V3 37 — 69 V9R 101 —
6 V4 38 — 70 Nehb-D 102 —
7 V5 39 — 71 Nehb-A 103 —
8 V6 40 — 72 Nehb-I 104 —
9 V7 41 — 73 — 105 —
a
10 (V2R) 42 — 74 — 106 —
11 V3R 43 — 75 — 107 —
12 V4R 44 — 76 — 108 —
13 V5R 45 — 77 — 109 —
14 V6R 46 — 78 — 110 —
15 V7R 47 — 79 — 111 —
16 X 48 — 80 — 112 —
17 Y 49 — 81 — 113 —
18 Z 50 — 82 — 114 —
19 CC5 51 — 83 — 115 —
a
Although V2R (10) is defined in other rules such as SCP-ECG, the definition shall not be used in MFER. V2R shall be
used as V1.
b
-aVR lead shall not be encoded according to MFER. The users (viewer) shall make a calculation to derive –aVR when
required.
Table 7 (continued)
Code Lead Code Lead Code Lead Code Lead
20 CM5 52 — 84 — 116 —
21 — 53 — 85 — 117 —
22 — 54 — 86 — 118 —
23 — 55 — 87 — 119 —
24 — 56 — 88 — 120 —
25 — 57 — 89 — 121 —
26 — 58 — 90 — 122 —
27 — 59 — 91 MCL 123 —
28 — 60 — 92 — 124 —
29 — 61 III 93 — 125 —
30 — 62 aVR 94 — 126 —
31 NASA 63 aVL 95 — 127 —
a
Although V2R (10) is defined in other rules such as SCP-ECG, the definition shall not be used in MFER. V2R shall be
used as V1.
b
-aVR lead shall not be encoded according to MFER. The users (viewer) shall make a calculation to derive –aVR when
required.
Table 8 — Lead name 2
Code Lead Remarks
175 SpO
In case status including pacing and lead off. Status should be
4160 Status
encoded in accordance with ISO/TS 22077-3.
4166 ECG1
4167 ECG2
These shall be used in case lead name is not definite.
4168 ECG3
4169 ECG4
4224 VO
4225 VCO
These signals about respiration gas are used in
4226 Tidal Volume
cardiopulmonary stress test.
4227 Respiratory Rate
4228 V
E
5.4 Sampling attributes
"Sampling interval (MWF_IVL)" and "Sampling resolution (MWF_SEN)" should be described in
accordance with ISO 22077-1. If multiple types of waveform are present, the sampling attributes
described immediately before description of their waveform data are used.
5.5 Frame attributes
"Data block length (MWF_BLK)", "Number of channels (MWF_CHN)" and "Number of sequences (MWF_
SEQ)" should be described in accordance with ISO 22077-1. If multiple types of waveform are present,
the frame attributes described immediately before description of their waveform data are used.
5.6 Pointer
This tag indicates the waveform data pointer, which is represented by the sampling rate of the root
level, in the frame. If no pointer is designated, the pointer of the first frame is initialized as zero. The
10 © ISO 2019 – All rights reserved

ISO/TS 22077-4:2
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