ISO 22077-2:2023
(Main)Health informatics — Medical waveform format — Part 2: Electrocardiography
Health informatics — Medical waveform format — Part 2: Electrocardiography
This document defines the application of medical waveform format encoding rules (MFER) to describe standard electrocardiography waveforms measured in physiological laboratories, hospital wards, clinics, and primary care medical checkups. It covers electrocardiography such as 12-lead, 15-lead, 18-lead, Cabrera lead, Nehb lead, Frank lead, XYZ lead, and exercise tests that are measured by inspection equipment such as electrocardiographs and patient monitors that are compatible with MFER. Medical waveforms that are not in the scope of this document include Holter ECG, exercise stress ECG, and real-time ECG waveform encoding used for physiological monitors.
Informatique de santé — Forme d'onde médicale — Partie 2: Electrocardiographie
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 22077-2
First edition
2023-08
Health informatics — Medical
waveform format —
Part 2:
Electrocardiography
Informatique de santé — Forme d'onde médicale —
Partie 2: Electrocardiographie
Reference number
ISO 22077-2:2023(E)
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ISO 22077-2:2023(E)
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© ISO 2023
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ISO 22077-2:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 2
4 Encoding format . 2
4.1 Primary description . 2
4.1.1 General . 2
4.1.2 Sampling attributes . 2
4.1.3 Frame attributes . 3
4.1.4 Waveform . 4
4.1.5 Channel . 6
4.2 Data alignment . 7
4.3 Abstract waveform . 7
4.4 Lead calculation. 7
4.5 Filter information . 8
4.5.1 Description of filter-processed data . 8
4.5.2 Description of filter use information . 9
5 Measurement information .9
5.1 General . 9
5.2 Measurement time (classification point) . 9
5.3 Measurement value . 10
5.4 Measurement information classification . 10
5.4.1 Observation event . 10
5.4.2 Waveform ancillary information . 10
5.4.3 Recording/display condition . 10
5.5 Power supply frequency . 11
5.6 Electrode condition . 11
5.7 Calibration waveform . 11
5.8 Artefact contamination. 11
5.9 Automatic interpretation code, etc. . 11
5.9.1 MFER interpretation code and heart beat code encoding rules .12
Annex A (informative) MFER Conformance statement .13
Annex B (informative) Waveform alignment .14
Annex C (informative) Encoding of waveform recognition point and measurement values .23
Annex D (informative) Reference table of coding scheme .30
Bibliography .34
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ISO 22077-2:2023(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO document should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had not received
notice of (a) patent(s) which may be required to implement this document. However, implementers are
cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all
such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee 215, Health informatics.
This first edition of ISO 22077-2 cancels and replaces ISO/TS 22077-2:2015, which has been technically
revised.
The main changes are as follows:
— clarified references in the text for all figures and tables;
— updated clause 3;
— corrected Figure 4, Figure C.1 and Figure C.4;
— deleted the description of "Unique identifier", "Measurement date/time", "Patient information", and
"Comment" that are described in ISO 22077-1;
— added and changed the description for some items of Annex B.
— deleted Annex E;
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.
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ISO 22077-2:2023(E)
Introduction
The standard 12-lead electrocardiography (ECG) is one of the most widely used medical waveforms in
clinical sites. In particular, the increased usage of electronic medical records provides the environment
in which these ECGs can be accurately utilized; however, to address the therapeutic requirements, ECG
use should not be constrained to specific machine types and manufacturers. Furthermore, the various
kinds of patient information contained in ECGs that are extensively studied and shared between health
care providers.
This document defines the detailed rules for the electrocardiography waveform format that is encoded
according to the medical waveform format encoding rules (MFER). Rules for other waveforms such as
long-term ECG (Holter ECG), stress ECG, etc. are contained in other MFER documents.
About MFER
Medical waveforms such as ECG, electroencephalography (EEG), and blood pressure waveforms
are widely utilized in clinical areas such as physiological examinations, electronic medical records,
medical investigations, research, education, etc. Medical waveforms are used in various combinations
and document types according to the intended diagnostic purpose. For example, ECG waveforms are
utilized extensively in the clinical arena, with resting 12-lead ECG being used the most. A cardiologist
typically makes diagnoses using 10 s to 15 s ECG waveform measurements; however, longer periods
are sometimes required to recognize heart conditions such as arrhythmia. Also, there are many other
methods using ECG such as Holter ECG, physiologic monitoring ECG, stress ECG, intracardiac ECG,
vectorcardiography (VCG), EEG with ECG, blood pressure with ECG, sleep polysomnography (PSG), etc.
MFER can describe not only ECG for physiological examinations conducted in intensive care unit (ICU)
and operating room acute care contexts, but also EEG, respiration waveforms, and pulse.
Implementation
MFER is a specialized representation for medical waveforms that removes unnecessary coded elements
(“tags”) for waveform description. For example, a standard 12-lead ECG can be described simply only
using a common sampling condition and the lead condition, making waveform synchronization and
correct lead calculation much easier.
Use with other appropriate standards
It is recommended that MFER only describes medical waveforms. Other information can be described
1) 2)
using appropriate standards including HL7® CDA, XML, and DICOM® . For example, clinical reports
that include patient demographics, order information, medication, etc. are supported in other standards
such as HL7® Clinical Document Architecture (CDA); by including references to MFER information in
these documents, implementation for message exchange, networking, database management that
includes waveform information becomes simple and easy.
Separation between supplier and consumer of medical waveforms
The MFER specification concentrates on data format instead of paper-based recording. For example,
recorded ECG is processed by filter, data alignment and other parameters, so that the ECG waveform
can be easily displayed using an application viewer. However, the ECG recordings displayed as images
are not as useful for other purposes such as data processing for research investigations. A design goal
of MFER is that a waveform is described in raw format with as complete as possible recording detail.
When the waveform is used, appropriate processing of the data is supported such as filtering, view
alignment, etc. In this way, the medical waveform described in MFER can be used for multiple purposes.
Product capabilities are not limited
1) HL7 is the registered trademark of Health Level Seven International. This information is given for the convenience
of users of this document and does not constitute an endorsement by ISO of the product named.
2) DICOM is the registered trademark of the National Electrical Manufacturers Association for its standards
publications relating to digital communications of medical information. This information is given for the convenience
of users of this document and does not constitute an endorsement by ISO of the product named.
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ISO 22077-2:2023(E)
Standards often support only a minimum set of requirements, so the expansion of product features
can be greatly limited. MFER can describe medical waveform information without constraining the
potential features of a product. Also, medical waveform display must be very flexible, and thus MFER
has mechanisms supporting not only a machine-readable coded system for abstract data, but also
human-readable representations.
The MFER specification supports both present and future product implementations. MFER supports the
translation of stored waveform data that was encoded using other standards, enabling harmonization
and interoperability. This capability supports not only existing waveform format standards, but it can
also be extended to support future formats as well.
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INTERNATIONAL STANDARD ISO 22077-2:2023(E)
Health informatics — Medical waveform format —
Part 2:
Electrocardiography
1 Scope
This document defines the application of medical waveform format encoding rules (MFER) to describe
standard electrocardiography waveforms measured in physiological laboratories, hospital wards,
clinics, and primary care medical checkups. It covers electrocardiography such as 12-lead, 15-lead, 18-
lead, Cabrera lead, Nehb lead, Frank lead, XYZ lead, and exercise tests that are measured by inspection
equipment such as electrocardiographs and patient monitors that are compatible with MFER.
Medical waveforms that are not in the scope of this document include Holter ECG, exercise stress ECG,
and real-time ECG waveform encoding used for physiological monitors.
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 22077-1, Health informatics — Medical waveform format — Part 1: Encoding rules
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1.1
dominant beat
primary heart beat extracted from typical beats for each lead in a 12-lead ECG
Note 1 to entry: The dominant beat is the beat used for primary measurement and analysis in a 12-lead ECG.
Note 2 to entry: In general, it is the typical beat excepting extrasystole or drifts of baseline.
3.1.2
average beat
beat waveform constructed from the average value of each temporal point in ECG across a number of
beats
Note 1 to entry: The average beat is used for the same purpose as the dominant beat.
Note 2 to entry: This is a waveform with the average value of waveforms excluding the abnormal beats for each
lead.
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ISO 22077-2:2023(E)
3.1.3
median beat
beat waveform constructed from the median value of each temporal point in ECG across a number of
beats
Note 1 to entry: The median beat is used for the same purpose as the dominant beat.
Note 2 to entry: This is a waveform with the median value of waveforms excluding the abnormal beats for each
lead.
3.1.4
tag
identifier code for a semantic concept
3.2 Abbreviated terms
DICOM® Digital Imaging and Communications in Medicine
ECG Electrocardiography
EEG Electroencephalography
HL7® Health Level Seven
MFER Medical waveform Format Encoding Rules
SCP-ECG Standard communication protocol — Computer-assisted electrocardiography (ISO 41064)
VCG Vectorcardiography
XML Extensible Markup Language
4 Encoding format
4.1 Primary description
4.1.1 General
This document provides the encoding of standard 12-lead ECG waveforms. It also supports encodings
other than standard 12-lead ECG for use in encoding other ECG waveforms such as Holter, stress
test, and real-time physiological monitoring. In addition, along with the ECG waveform encoding, the
encoding of waveform recognition information, measurement information, interpretation information,
etc. is provided, but these are all optional functions and depend on each implementation concept. For
instance, along with MFER-encoded waveforms, interpretation codes or measurement values are
described in other standards including HL7® CDA, XML, and DICOM®.
All encoding rules shall apply the requirements described in ISO 22077-1.
In order to make effective use of this document, a MFER conformance statement is provided in Annex A.
4.1.2 Sampling attributes
Sampling attributes including sampling rate and resolution are given in Tables 1 to 4.
4.1.2.1 MWF_IVL (0Bh): Sampling rate
This tag indicates the frequency or sampling interval for the medical waveform is sampled (Table 1).
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ISO 22077-2:2023(E)
Table 1 — Sampling rate
Data Duplicated defini-
MWF_IVL Default Encoding range/remarks
length tions
Unit 1 —
-128 to +127
11 0Bh Exponent (10th power) 1 1 000 Hz 10 Override
Mantissa ≤4 e.g. unsigned 16-bit integer
The unit can be frequency in hertz, time in seconds, or distance in meters (Table 2).
Table 2 — Sampling rate unit
Unit Value Remarks
Frequency Hz 0 Including power
Time interval s 1 —
4.1.2.2 MWF_SEN (0Ch): Sampling resolution
This tag indicates the resolution, minimum bits, the medical waveform sampled (generally, digitized)
(Table 3).
Table 3 — Sampling resolution
Duplicated
MWF_SEN Data length Default Encoding range/remarks
definitions
Unit 1 —
-128 to +127
12 0Ch Exponent (10th power) 1 See Table 4 10 Override
Mantissa ≤4 e.g. unsigned 16-bit integer
Table 4 — Sampling units
Unit Value Default Remarks
Voltage Volt 0 0,000 001 V —
4.1.3 Frame attributes
4.1.3.1 General
A frame is composed of data blocks, channels and sequences.
4.1.3.2 MWF_BLK (04h): Data block length
This tag indicates the number of data sampled in a block (Table 5).
Table 5 — Data block length
MWF_BLK Data length Default Remarks Duplicated definitions
04 04h ≤4 1 — Override
4.1.3.3 MWF_CHN (05h): Number of channels
This tag indicates the number of ECG channels (Table 6). If a previously specified channel attribute is
reset to the root definition including Default, the number of channels should be specified before each
definition of the channel attribute. The number of channels cannot be specified within the definition of
a channel attribute.
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Table 6 — Number of channels
MWF_CHN Data length Default Remarks Duplicated definitions
05 05h ≤4 1 — Override
4.1.3.4 MWF_SEQ (06h): Number of sequences
This tag indicates the number of sequences (Table 7). If the number of sequences is not designated, it
depends on the data block length, the number of channels and the number of waveform data values that
are defined for the specified frame.
Table 7 — Number of sequences
MWF_SEQ Data length Default Remarks Duplicated definitions
06 06h ≤4 Depends on waveform data length — Override
4.1.4 Waveform
The waveform class and type, waveform attributes and waveform data are encoded as follows.
4.1.4.1 MWF_WFM (08h): Waveform class
Waveforms such as standard 12-lead ECG and monitoring ECG are grouped based on instruments and
purpose, as shown in Table 8.
Table 8 — Waveform class
MWF_WFM Data length Default Remarks Duplicated definitions
2 Non-specific waveform —
08 08h Override
Str ≤ 32 Waveform description —
As a general rule, each type of waveform is described in a separate specification.
For types of waveforms (Table 9), numbers 1 to 49151 (BFFFh) are reserved. Numbers 49152 to 65535
can be used privately, but it is recommended to add these to the MFER specification rather than rely on
private extensions.
Table 9 — Standard 12-lead ECG waveforms
Waveform kind Type Value Waveform description Remarks
ECG_STD12 1 Standard 12-lead ECG Standard 12-lead ECG including
general ECG in short-term record-
ing.
ECG_BEAT 9 QRS beat In general, one heart beat wave-
form extracted from standard
Electrocardiogra-
12-lead ECG recording.
phy
Write comment
Average, Median, Dominant
ECG_DRV 12 Derived lead Derived ECG from Frank vector
leads, EASI lead, etc.
4.1.4.2 MWF_LDN (09h): Waveform attributes (lead name, etc.)
Code and information can be added to the type of waveform (Table 10). Table 11 shows lead name code
used in 12-lead ECGs and vector lead ECGs. Because the lead code is encoded by 0 to 127, care should be
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ISO 22077-2:2023(E)
taken when other standards such as SCP-ECG, etc. are followed. Since part of these code spaces overlap,
the present table shall be followed in all MFER applications.
Since in this specification, the code for the lead name is encoded by 127 or less, the codes specified in
systems such as SCP-ECG shall require conversion. However, in the present lead code table, leads which
are not used in standard 12-lead ECG are defined and, in general, will not need to be replaced.
Table 10 — Definition of waveform attributes
Data Duplicated
MWF_LDN Default Description range, remarks
length definition
Waveform code 2 Data length = 2, if waveform
information is encoded
09 09h Undefined Override
Waveform information Str ≤ 32 —
The present code supports 12-lead electrocardiography waveforms. It is recommended to encode leads
using MFER waveform information, rather than those specified in other standards.
In addition, this document extends the 12-lead names for humans to include ECG lead names for animals.
When other leads for animals are used, such as CV5RL, CV6LL, CV6LU, and V10, they should be specified
by waveform information.
Table 11 — Lead name
Code Lead Code Lead
1 I — —
2 II — —
3 V1 — —
4 V2 — —
5 V3 — —
6 V4 — —
7 V5 — —
8 V6 — —
9 V7 — —
b
10 — —
11 V3R 61 III
12 V4R 62 aVR
13 V5R 63 aVL
14 V6R 64 aVF
a
15 V7R 65 -aVR
16 X 66 V8
17 Y 67 V9
18 Z 68 V8R
19 CC5 69 V9R
20 CM5 70 D(Nehb Dosal)
— — 71 A(Nehb Anterior)
31 NASA 72 J(Nehb Inferior)
32 CB4 — —
a
aVR lead shall not be encoded according to MFER. The users (viewer)
should mke a calculation to derive -aVR when required.
b
Although V2R (10) is defined in other rules such as SCP-ECG, the definition
shall not be used in MFER.
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ISO 22077-2:2023(E)
TTaabbllee 1111 ((ccoonnttiinnueuedd))
Code Lead Code Lead
33 CB5 — —
34 CB6 — —
a
aVR lead shall not be encoded according to MFER. The users (viewer)
should mke a calculation to derive -aVR when required.
b
Although V2R (10) is defined in other rules such as SCP-ECG, the definition
shall not be used in MFER.
Code and information can be added to the type of waveform. If a waveform is required to be
reconfigured, as in the case of deriving leads III and aVF from leads I and II, the codes should always be
specified. The codes should be taken into special consideration as they have a function to specify some
processing, as in the case of deriving other limb leads from leads I and II or deriving a waveform based
on the lead name. See Annex D for the definition of waveform attributes.
As the lead names are defined depending on the class of waveform, the lead subsets are not called out
for each class of waveform in MFER. Thus, caution should be taken in encoding lead names.
For waveform codes, numbers 1 to 49151 (BFFFh) are already reserved. Numbers 49152 to 65535 can
be used privately but it is recommended to add these to the MFER specification rather than rely on
private extensions.
4.1.4.3 MWF_WAV (1Eh): Waveform data
The entire set of waveform data should be strictly aligned as defined in Frame attributes. If the
waveform data are compressed, the data alignment can depend on the compression method, but the
waveform data after un-compressing should be aligned according to the definition. Refer to Annex B.
If waveform data are different from what is defined in frame information, they can be discarded
depending on application processing. MFER behaviour is undefined in this case.
4.1.5 Channel
4.1.5.1 MWF_ATT (3Fh): Channel attributes (channel definition)
This tag defines the attributes for each channel (see Table 12). Before this definition, the channel
number shall be specified using the values in Table 6.
Table 12 — Channel attributes
MWF_ATT Data length Default Remarks Duplicated definitions
63 3Fh Depends on definition — — Override
NOTE Channel definition for each channel is encoded with a special context tag of P/C = 1 and tag number of
1Fh. That is, the type number is P/C + tag number encoded with 3Fh and identifies the attribute of the relevant
channel.
For the tag of the channel attribute definition, context mode is selected with P/C (bit 6 = 1) (Figure 1).
Figure 1 — Number of channel
The data length includes all the range of the channel attribute definition (Figure 2).
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Figure 2 — Definition of channel attributes
The channel attribute definition can be described with the indefinite length (Figure 3).
Figure 3 — Definition of channel attributes with indefinite length
4.2 Data alignment
This document supports many ECG alignment styles according to Annex B, allowing for complicated
alignment formats that could result in processing issues. It is recommended that formats be simplified
as much as possible in order to maximize interoperability.
4.3 Abstract waveform
This example is in principle the same as the 12-lead ECG, but one heart
...
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