ISO 22077-2:2023

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

General Information

• Status: Published
• Publication Date: 30-Aug-2023
• ICS: 35.240.80 - IT applications in health care technology
• Technical Committee: ISO/TC 215 - Health informatics
• Drafting Committee: ISO/TC 215 - Health informatics
• Current Stage: 6060 - International Standard published
• Start Date: 31-Aug-2023
• Due Date: 22-Feb-2024
• Completion Date: 31-Aug-2023

Relations

• Revises: ISO/TS 22077-2:2015 - Health informatics — Medical waveform format — Part 2: Electrocardiography
• Effective Date: 06-Jun-2022

Overview

ISO 22077-2:2023 - "Health informatics - Medical waveform format - Part 2: Electrocardiography" specifies how to apply the Medical waveform Format Encoding Rules (MFER) to describe standard electrocardiography (ECG) waveforms. It defines structured encoding for ECG recordings taken in physiological labs, hospital wards, clinics and primary care, enabling machine-readable, device‑neutral waveform storage and exchange. The standard is the first edition (2023) and replaces ISO/TS 22077-2:2015.

Key topics

• Scope of ECG types covered: encoding rules for 12‑lead, 15‑lead, 18‑lead, Cabrera lead, Nehb lead, Frank lead, XYZ lead and certain exercise tests recorded by electrocardiographs and MFER‑compatible patient monitors.
• Exclusions: Holter ECG, exercise stress ECG and real‑time ECG waveform encoding for physiological monitors are explicitly out of scope.
• Encoding format elements: primary description (sampling attributes, frame attributes, waveform and channel descriptions), data alignment, abstract waveform representation and lead calculation rules.
• Signal processing metadata: standardized description of filter‑processed data and filter use information to preserve provenance of processed waveforms.
• Measurement information: measurement time/classification, measurement values, observation/event classification, electrode condition, calibration waveform, artifact contamination and automatic interpretation codes (MFER interpretation and heartbeat codes).
• Normative and informative annexes: conformance statement, waveform alignment guidance, encoding of recognition points and measurement values, plus reference coding tables and bibliography.

Applications

ISO 22077-2:2023 supports practical interoperability and reuse of ECG data for:

• Medical device manufacturers - implement standardized waveform export for ECG machines and patient monitors.
• EHR/EMR and PACS vendors - ingest and archive ECG waveforms in a structured, interoperable format.
• Clinical sites and cardiology labs - ensure consistent recording metadata (filters, calibration, electrode status) for diagnostic accuracy and legal traceability.
• Health IT integrators and software developers - build viewers, analytics, and AI models that rely on well‑described, device‑neutral ECG inputs.
• Research and registries - harmonize multicentre ECG datasets for studies and quality assurance.

Related standards

• ISO 22077-1 (MFER encoding rules) - normative reference for format rules.
• Integrations recommended with HL7 CDA, XML and DICOM for richer clinical documents and imaging workflows.

Keywords: ISO 22077-2:2023, MFER, electrocardiography, ECG format, medical waveform format, health informatics, ECG interoperability, 12‑lead ECG, waveform encoding.

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 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
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
iii
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.
iv
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.
v
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.
vi
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.
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).
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.
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
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.
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).
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 heartbeat of P-QRS-T is extracted and
expressed (see Figure 4). The abstract waveform is processed in three ways: extraction as dominant
beat, average beat and median beat. These depend on the system concept and measurement method.
The abstract waveform should be clearly stipulated in implementation specifications, but all leads can
be encoded by abstract waveform of MFER.
Figure 4 — Abstract waveform
4.4 Lead calculation
Recent electrocardiographs frequently adopt systems to record limb leads by Leads I and II only. In such
event, Leads III, aVR, aVL, and aVF shall be calculated. Derivation shall be performed by the following
operations (see Table 13, Table 14, Table 15):
In implementing lead calculation, thorough consideration shall be given to aspects such as A/D
conversion method, phase deviation or electrode disconnection, and care must be practiced to prevent
occurrence of arithmetic waveform distortion.
Table 13 — Lead calculation operation table (calculation from leads I and II)
Lead name Calculation Computation (right arm potential R; left arm potential L, left foot
operation potential F)
III II – I III = F–L = (F–R)– (L–R) where, II = F - R and I = L - R
aVR –(I + II)/2 aVR = R–(L+F)/2 = {(R–L)+(R–F)}/2
aVL I – II/2 aVL = L–(R+F)/2 = {(L–R)+(L–F)}/2 = (I–III)/2 = I–II/2
aVF II – I/2 aVF = F–(R+L)/2 = {(F–R)+(F–L)}/2 = (II+III)/2 = II–I/2
-aVR Inverted aVR
Table 14 — Lead calculation operation table (calculation from leads I and III)
Lead name Calculation Computation (right arm potential R; left arm potential L, left foot
operation potential F)
II III+ I II = F–R = (F–L)+ (L–R) where, III = F - L and I = L - R
aVR – I – III/2 aVR = R–(L+F)/2 = {(R–L)+(R–F)}/2 = {–I–(III+I)}/2 = –I–III/2
aVL (I – III)/2 aVL = L–(R+F)/2 = {(L–R)+(L–F)}/2 = (I–III)/2
aVF III + I/2 aVF = F–(R+L)/2 = {(F–R)+(F–L)}/2 = {(III+I)+III}/2 = III+I/2
-aVR Inverted aVR
Table 15 — Lead calculation operation table (calculation from leads II and III)
Lead name Calculation Computation (right arm potential R; left arm potential L, left foot poten-
operation tial F)
I II – III I = L–R = (F–R)– (F–L) where, II = F - R and III = F - L
aVR –II + III/2 aVR = R–(L+F)/2 = {(R–L)+(R–F)}/2 = {– (II–III) –II }/2 = –II+III/2
aVL –III + II/2 aVL = L–(R+F)/2 = {(L–R)+(L–F)}/2 = {(II–III) –III}/2 = –III+II/2
aVF (II +III)/2 aVF = F–(R+L)/2 = {(F–R)+(F–L)}/2 = (II+III)/2
-aVR Inverted aVR
Sampled ECG data for all leads shall be completely synchronized.
4.5 Filter information
When filter information is described in MFER, it is classified in two cases: filter-processed data and
non-filtered use information.
4.5.1 Description of filter-processed data
Description is made on the filter information processed for the data described by MFER (see Tables 16
and 17).
Table 16 — Filter information
MWF_FLT Data length Duplicated definitions
17 11h Str < 256 Possible
Table 17 — Filter description example
Filter function Abbreviation Example Meaning
Filter information None Hum filter ON Hum filter (characteristics, etc. not specified)
only used.
High-frequency HPF HPF = 0,05 Indefinite characteristics 0,05 Hz low frequency
pass filter cutoff (high-pass) filter used.
Low-frequency pas LPF LPF = 150^secondary Butterworth secondary characteristics 150 Hz
filter Butterworth filter high frequency cutoff (low-pass) filter used.
Band elimination BEF BEF = 50^Hum filter 50 Hz Hum filter used. Cutoff characteristics not
filter known.
In ECG, high-pass (low frequency cutoff) filter is frequently described by the time constant, but in MFER,
it is recommended to describe it by frequency. For example, the low frequency cutoff filter, which has
the primary Butterworth characteristics shown by frequently used CR, is described by the following:
By High-Pass Filter = 1/ωT, the lower cutoff frequency of time constant of 3 s is described by 1/
(2π × 3 s) ≈ 0,05 Hz.
4.5.2 Description of filter use information
In this case, MFER ECG data has not been subject to filter processing, and the fact that a specific filter is
used is stipulated only. For example, this information can be used to indicate that the ECG was measured
by an electrocardiograph, printed on recording paper underwent the relevant filter processing and can
be utilized for diagnosis.
5 Measurement information
5.1 General
Out of information generated during measuring ECG, information that would exert effect on the
authenticity of ECG and validity of waveforms is encoded. For example, it is possible to encode waveform
display information and power supply frequency that do not exert effect on the generating of ECG
waveform measurement but that are required to reproduce the condition at the time of measurement.
The descriptions in this clause should be implemented in accordance with appropriate standards
including HL7® CDA, XML, and DICOM®.
Refer to Annex C.
5.2 Measurement time (classification point)
The measurement time (classification point) is encoded by MWF_EVT format (Table 18).
Table 18 — Event
Data Duplicated defini-
MWF_EVT Encoding range/remarks
length tions
Event code 2
Starting time (point) 4 Number of samples acquired at the
65 41h sampling interval defined in the root Possible
Duration 4
definition
Event information Str < 256
When the recognition point of ECG waveform is shown (Figure C.1), it is encoded by the event code.
When the recognition point in an ECG waveform is encoded by the root definition, it applies to all leads.
When it is in a channel definition (each channel), the recognition point shall only apply to that channel.
By specifying the lead inside the channel definition, the recognition point of each lead can be encoded.
If the waveform is not encoded using MFER, then the lead should be specified in the channel definition.
5.3 Measurement value
The measurement value is encoded by MWF_VAL (Table 19).
Table 19 — Measurement value
Data
MWF_VAL Encoding range/remarks Duplicated definition
length
Value code 2
Time point 4 Number of data values sampled is
Multiple definitions avail-
66 42h encoded.
able
Value Str ≤ 32 Value is encoded with a character
string with unit (“^”).
5.4 Measurement information classification
5.4.1 Observation event
Events that have actually occurred, such as clinical observations, can be encoded by the use of MWF_
EVT (Table 20).
Table 20 — Event information
MWF_EVT Data length Encoding range/remarks Duplicated definition
Event code 2
Starting time (point) 4 Number of data values ac-
65 41h quired at the sampling interval Possible
Duration 4
defined in the root definition.
Event information Str < 256
5.4.2 Waveform ancillary information
Information that possibly exert an effect on the waveform, such as power supply frequency, shall be
encoded using MWF_INF (Table 21).
Table 21 — Waveform ancillary information
Duplicated defini-
MWF_INF Data length Encoding range/remarks
tions
Ancillary information 2
code
Starting time (point) 4 Number of data values acquired
21 15h Possible
at the sampling interval defined
Duration 4
in the root definition.
Waveform information Str < 256
5.4.3 Recording/display condition
"MWF_CND" is for describing an electrocardiograph recording and screen image conditions such as
lead name and recording pattern. Doctors diagnose not only by an electrocardiograph recording and
screen image, but also by displaying ECGs in EMR systems. An electrocardiograph recording and screen
image can be reproduced using "MWF_CND".
Table 22 — Recording/display, etc. information
MWF_CND Data length Remarks Duplicated definitions
Recording/display 2
condition
Description code 1 2
68 44h Description code 2 2 Possible
Starting point 4
Duration 4
Descriptive information Str < 256
5.4.3.1 Waveform display example
Recording lead combinations used when ECG is measured are encoded by MWF_CND (Table 22):
Tag: MWF_CND
Recording/display condition: MWF_ECG_LEADS (65030)
Description code 1: channel No. 1 –
Description code 2: lead name
Starting point: record starting point
Duration: Relevant recording time
5.4.3.2 Recording sensitivity display example
The recording sensitivity used at the time of recording is encoded.
5.5 Power supply frequency
The power supply frequency can be encoded. In general, the electrocardiograph has an AC interference
elimination filter, but recording without filter processing and adding encoding of power supply
frequency can eliminate AC interference by secondary processing.
5.6 Electrode condition
This can be specified when electrodes are disconnected. In particular, in the event that lead composition
is performed, the derivation operation will not be performed accurately, a possible situation that should
be thoroughly taken into account in implementation.
5.7 Calibration waveform
Encoding can be performed when the calibrated waveform is implemented.
5.8 Artefact contamination
This code can be used to indicate that artefact and noise get mixed at the time of measuring ECG.
5.9 Automatic interpretation code, etc.
The Interpretation code is used for an automatic analysis system, but in the event that this function can
be represented using another protocol such as HL7®, it that protocol should be used.
5.9.1 MFER interpretation code and heart beat code encoding rules
Interpretation statements code and beat annotation can be encoded using the event tag (see Table 23).
Table 23 — Automatic interpretation code
MWF_EVT Data length Encoding range/remarks Duplicated definitions
Interpretation 2
See Figure 5
statements code
Starting time 4 Number of data values acquired at
(point) the sampling interval defined in
the root definition.
65 41h Possible
Duration 4
Interpretation Str < 256
statements de-
scrip-tive informa-
tion
Figure 5 — Composition of interpretation statements code
The interpretation statements code is composed with 128 - 8191.
The question bit code means:
0: Undesignated (finalization or designation is not particularly needed)
1: In the event that there is little possibility of rendering an opinion
2: When there is any question
3: When there is strong question
and is able to designate the following supplementation:
a) Interpretation code
When the applicable opinion is encoded throughout the whole frame, definition shall be made in
the root definition region. In the event that no event information is used, both starting time and
duration are not used. In the case that event information is used, “zero” shall be employed for both
starting time and duration.
b) Waveform classification for each heart beat
The time of the position of the applicable heart beat shall be designated as the starting time and no
duration time is used. When the event information is used, the duration shall be set to “zero” and
the event information is used.
c) Waveform classification within the period
For example, transient bundle branch block, etc. are encoded, using the starting time and duration,
the relevant regional time shall be specified.
d) When waveform classification is encoded simultaneously with event information, event code and
event information can be specified at the same time, or the event code = 0 and the event information
can be encoded.
Annex A
(informative)
MFER Conformance statement
Each implementer should provide a specification sheet of their MFER waveform format using the
conformance statement in Table A.1. Use of non-default values should be identified clearly. If the
extension capabilities of the MFER description are used, an additional sheet with these optional
extensions should also be provided.
Table A.1 — Conformance statement template
MFER specification Frame / Ver.
Producer Manufacturer Date Model
Author Edited date
Waveform title Specification
Preamble Endianity • Default(big endian) • Big endian • Little
endian
Version . Character
Sampling Sampling rate Unit Exponent Mantissa
attributes
Sampling resolution Unit Exponent Mantissa
Data type • Default • ( ) NULL • Not used • ( ) Offset value • Not used • ( )
Frame number Block Channel Sequence
Channel No. Lead or Waveform Condition Remarks

Note
Annex B
(informative)
Waveform alignment
NOTE In this section, the term “channel” is used differently from the “channel attributes” of the frame
referred to in MFER Part 1 according to traditional electrocardiography. Be careful to avoid any misunderstanding
in its interpretation. For example, a 3-channel ECG has a different meaning from the channel attributes of the
MFER frame.
B.1 1-channel ECG
B.1.1 General
This model describes the oldest type of 1-channel electrocardiograph, where an ECG is recorded by
measuring over one lead. For each lead, the frame is encoded and the waveform length is variable
(Figure B.1). Waveforms can be viewed in chronological order, but the format should be properly changed
for display or recording as is the case with the realignment to 3x4 leads of Figure B.2. This encoding is
old-fashioned as an electrocardiograph but is still popularly used for a biological information monitor,
for example.
B.1.2 1-channel ECG recording
ECG is recorded frame by frame and relevant lead waveform is not ensured of temporal continuation.
Consequently, time-phase that bestrides leads, for example, RR interval, has no meaning.
Figure B.1 — 1-channel ECG
B.1.3 3-channel realignment of waveforms recorded in 1-channel ECG
In this case, 1-lead ECGs that are shown in 1-channel ECG of Figure B.1 are realigned into 3x4 leads
(Figure B.2). In such events, the waveform phase between channels is not compensated and there is no
synchronism in each heartbeat.
Figure B.2 — Realignment to 3x4 leads
B.1.4 6-channel realignment of waveforms recorded in 1-channel ECG
This is a case in which 1-lead ECG shown in 1-channel ECG of Figure B.1 is realigned into 6x2 leads
(Figure B.3). In such event, the waveform phase between channels is not compensated and there is no
synchronism in each heartbeat.
Figure B.3 — Realignment to 6x2 leads
B.2 Multichannel ECG
This is a model to represent
...