ISO 11073-91064:2009

Health informatics — Standard communication protocol — Part 91064: Computer-assisted electrocardiography

ISO 11073-91064:2009 specifies the common conventions required for the cart-to-host as well as cart-to-cart interchange of specific patient data (demographic, recording, ...), ECG signal data, ECG measurement and ECG interpretation results. ISO 11073-91064:2009 specifies the content and structure of the information that is to be interchanged between digital ECG carts and computer ECG management systems, as well as other computer systems where ECG data can be stored.

Informatique de santé — Communication entre dispositifs médicaux sur le site des soins — Partie 91064: Protocole de communication standard pour l'électrocardiographie assistée par ordinateur

General Information

• Status: Withdrawn
• Publication Date: 04-May-2009
• 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: 9599 - Withdrawal of International Standard
• Completion Date: 27-Jun-2023

Relations

• Revised: ISO 41064:2023 - Health informatics — Standard communication protocol — Computer-assisted electrocardiography
• Effective Date: 06-Jun-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 11073-91064
First edition
2009-05-01


Health informatics — Standard
communication protocol —
Part 91064:
Computer-assisted electrocardiography
Informatique de santé — Communication entre dispositifs médicaux sur
le site des soins —
Partie 91064: Protocole de communication standard pour
l'électrocardiographie assistée par ordinateur





Reference number
ISO 11073-91064:2009(E)
©
ISO 2009

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ISO 11073-91064:2009(E)
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ISO 11073-91064:2009(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Abbreviations . 3
5 Definition of the data contents and format . 4
5.1 General considerations. 4
5.2 Specifications for the data structure . 5
5.3 Pointer section – Section 0. 8
5.4 Header information – Patient data/ECG acquisition data – Section 1. 10
5.5 Huffman tables – Section 2. 23
5.6 ECG lead definition – Section 3. 24
5.7 QRS locations, reference beat subtraction zones and protected areas – Section 4 . 30
5.8 Encoded type 0 reference beat data – Section 5 . 32
5.9 Rhythm data – Section 6 . 34
5.10 Global measurements – Section 7 . 36
5.11 Storage of full text interpretive statements – Section 8 . 41
5.12 Storing manufacturer specific interpretive statements and data related to the overreading
trail – Section 9 . 43
5.13 Lead measurement block – Section 10.43
5.14 Storage of the universal ECG interpretive statement codes – Section 11. 46
6 Minimum requirements for encoding and compression of the ECG signal data. 48
6.1 Scope and field of application. 48
6.2 Introduction . 48
6.3 ECG compression methodology. 49
6.4 Main results from investigations on ECG data compression in the SCP-ECG Project. 50
6.5 Minimum requirements for ECG data compression. 51
Annex A (normative) Encoding of alphanumeric ECG data in a multilingual environment . 53
Annex B (normative) Definition of compliance with the SCP ECG standard. 66
Annex C (normative) Methodology and conformance testing of the recommended ECG signal
compression technique. 74
Annex D (informative) Definition of a minimum set of control and query messages for the
interchange of ECG data. 106
Annex E (informative) Standard low-level ECG-Cart to host protocol. 121
Annex F (informative) Universal ECG interpretation statements codes. 132
Annex G (informative) Glossary. 154
Bibliography . 156

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ISO 11073-91064:2009(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 11073-91064 was prepared by Technical Committee ISO/TC 215, Health informatics.
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ISO 11073-91064:2009(E)
Introduction
The electrocardiogram (ECG) is a recording of voltage changes transmitted to the body surface by electrical
events in the heart muscle, providing direct evidence of cardiac rhythm and conduction, and indirect evidence
of certain aspects of myocardial anatomy, blood supply and function. During its propagation to the surface,
extracardiac tissues may intervene and influence the ECG.
Electrocardiography has been used for many years as a key, non-invasive method in the diagnosis and early
detection of coronary heart disease, which is the leading cause of mortality in western countries. In 1993, it
was estimated that more than 100 million standard ECGs are recorded yearly in the European Community
(EC) for routine diagnostic and screening purposes at an estimated cost of more than 1,2 billion € per year.
Almost all newer electrocardiographs nowadays use digital recording, interpretation and communication
techniques. These stand-alone, microcomputer based machines can be connected to each other, and to
larger minicomputer-based management servers for long-term storage and serial comparison. To this end,
various manufacturers have used different techniques.
It is in the general public interest for users not to be restricted in their options by incompatible technical
features and services of different systems. ECG processing is increasingly being integrated with various other
data processing in health care. This evolution shall have considerable impact on the storage and
communication of ECG data. There are many different end-users who for different purposes (support of
patient care, management, research and education) want to obtain a copy of the signal data, of the
interpretive report and/or measurement results. Being one of the very first systems for medical decision
support, computerized ECG interpretation stretches from departments of cardiology in hospitals, to general
practitioners in primary care and health care centres. In life-threatening acute myocardial infarction, ECGs are
being used in ambulances by paramedical personnel to assess the necessity for administering thrombolytic
agents, with long-distance monitoring whenever possible.
To enable the exchange of information between various systems it was of utmost importance that a standard
communications protocol for computer-aided electrocardiography (SCP-ECG) had to be established, as
defined in this document. The primary aim of this document is to specify a data format for transferring ECG
reports and data from any vendor's computerized ECG recorder to any other vendor's central ECG
management system. The same standard should also allow standardized transfer of digitized ECG data and
results between various computer systems.
Under the standard communication protocol (SCP) the contents and format of the ECG waveform data and
the measurements from ECG devices of different manufacturers are not expected to be identical. As a result,
the determination of the suitability of a device and/or system for any particular application remains with the
user/purchaser. The following possible uses of ECG records require special attention:
⎯ serial comparison of ECGs and interpretations;
⎯ plot formats of ECGs;
⎯ maintaining audit trail of edits;
⎯ bi-directional communication and remote query.
The user is cautioned to make sure that the data contents and format of the waveform data, measurements,
and the interpretive statements meet his or her specific needs. If more than one type of ECG device and/or
database management system are interconnected, the user is also advised to verify with the manufacturers
that the data from different systems are compatible with each other and with the user’s needs.
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ISO 11073-91064:2009(E)
In order to understand this document, the reader needs some basic understanding of electrocardiology,
electrocardiography and signal processing.
This part of ISO 11073 relates to the conventional recording of the electrocardiogram, i.e. the so-called
standard 12-lead electrocardiogram and the vectorcardiogram (VCG). Initially, the electrical connections used
for recording the ECG were made to the limbs only. These connections to the right arm (RA), left arm (LA), left
leg (LL) and right leg (RL) were introduced by Einthoven. The electrical variations detected by these leads are
algebraically combined to form the bipolar leads I, II and III. Lead I, for example, records the difference
between the voltages of the electrodes placed on the left arm and the right arm. The unipolar
electrocardiographic leads (aVR, aVL, aVF and the precordial leads V1 to V6) were introduced much later,
starting in 1933. In these leads, potentials are recorded at one location with respect to a level which does not
vary significantly in electrical activity during cardiac contraction. The “augmented” limb lead potentials are
recorded with reference to the average potential of (L+F), (R+F) and (L+R) respectively. The unipolar chest
(RA+RL+LL)
leads are recorded with reference to the average potential of which is called the Wilson “central
3
terminal” (CT). In vectorcardiography, recordings are made of three mutually perpendicular leads, running
parallel to one of the rectilinear coordinate axes of the body. The axes are the X-axis going right to left, the Y-
axis with a top to bottom orientation and the Z or front to back axis.
In some research centres, so-called body surface maps are obtained by placing many (from 24 to 124 or even
more) closely-spaced electrodes around the torso. This part of ISO 11073 has not been designed to handle
exchanges of such recordings, although future extensions could be made to this end. This part of ISO 11073
has also not been designed to exchange specialized recordings of intracardiac potentials or of the so-called
Holter or other long-term ECG recordings made for monitoring cardiac rhythm. This part of ISO 11073 also
does not address exercise ECG recordings.
ECG computer processing can be reduced to three principal stages:
1) data acquisition, encoding, transmission and storage;
2) pattern recognition and feature extraction, i.e. ECG measurement;
3) diagnostic classification.
In each of these stages there are important needs for standardization and quality assurance testing. The
scope of this part of ISO 11073 is confined to the first of these three stages.
The various data sections that shall be transmitted by means of the standard ECG communications protocol
are defined in Clause 5. Minimum requirements for data encoding and compression are defined in Clause 6.
The compliance categories defined in Annex B provide users and manufacturers of ECG devices and/or
systems with a relatively simple codification of SCP-ECG related features and information content that may be
provided by a specific device. Two data format categories have been defined based on information content as
in Table 1.
Table 1 — Data format categories for compliance specifications
Category Data sections required Content description
I 0, 1, [2], 3, 6, (7), (8), (10) Demographics, and ECG rhythm data (uncompressed or with
lossless compression)
II 0, 1, [2], 3, 4, 5, 6, (7), (8), (10) Demographics, ECG rhythm data (uncompressed, with lossless
compression or with high compression), and reference beats
NOTE 1 Square brackets [ ] indicate that data section 2 is required if Huffman encoding has been used.
NOTE 2 Parentheses ( ) indicate that these data sections are optional for export.

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ISO 11073-91064:2009(E)
A further category may be added in future versions in order to fulfil the specific needs of ECG devices used in
other applications (such as telemedicine or homecare).
All devices stating an SCP-ECG data format category shall import at minimum data sections 0, 1, 3, 6, 7 and
8. All categories may have additional sections added (e.g. 9, 10, 11). Manufacturer-specific data shall be
optionally included only in manufacturer-specific fields, bytes and data blocks that have been defined in the
document. Reserved, unspecified and undefined fields, bytes or data blocks shall not be used for
manufacturer-specific data.
For a particular device, an SCP-ECG compliance statement lists data format category(ies) for export
(i.e. acquiring and making available an SCP-ECG record) and import (i.e. accepting, and making available to a
user, an SCP-ECG record). A device may also state its ability to transfer (i.e. making available an SCP-ECG
record without changing its data format, for example, exporting a record that was previously imported). (These
terms are precisely defined in Annex B for the purpose of this part of ISO 11073).
The selection and definition of ECG-specific high-level syntaxes for transfer of messages and data host-to-
hosts, such as EDIFACT or ASN.1, are beyond the scope of this part of ISO 11073.

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INTERNATIONAL STANDARD ISO 11073-91064:2009(E)

Health informatics — Standard communication protocol —
Part 91064:
Computer-assisted electrocardiography
1 Scope
This part of ISO 11073 specifies the common conventions required for the cart-to-host as well as cart-to-cart
interchange of specific patient data (demographic, recording, .), ECG signal data, ECG measurement and
ECG interpretation results.
This part of ISO 11073 specifies the content and structure of the information that is to be interchanged
between digital ECG carts and computer ECG management systems, as well as other computer systems
where ECG data can be stored.
2 Normative references
The following referenced documents are indispensable for the application 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/IEC 646, Information technology — ISO 7-bit coded character set for information interchange
ISO/IEC 2022:1994, Information technology — Character code structure and extension techniques
ISO/IEC 4873, Information technology — ISO 8-bit code for information interchange — Structure and rules for
implementation
ISO/IEC 8859-1, Information technology — 8-bit single-byte coded graphic character sets — Part 1: Latin
alphabet No. 1
JIS X 0201-1976, Code for Information Interchange
JIS X 0208-1997, Code of the Japanese Graphic Character Set for Information Interchange
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
acquiring cardiograph
cardiograph recording the original ECG signal
3.2
bimodal compression
use of low pass filtering and sample decimation outside of a protected zone containing the QRS complex, with
no decimation or filtering within the protected zone, indicated by 5.9.3 byte 6
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ISO 11073-91064:2009(E)
3.3
confirming
process whereby a trained and experienced cardiologist reviews the computer-generated (or overread)
interpretation of an ECG in order to confirm the computer-generated (or overread) interpretation or to make
the final changes to the interpretation text
NOTE The confirmed ECG is the final clinically acceptable version for diagnosis and treatment.
3.4
CSE Project
project supported by DG XII of the European Commission aiming at the development of Common Standards
for (Quantitative) Electrocardiography
3.5
downsampling factor
decimation factor
factor that gives the reduction of samples in data sections where the sampling rate is reduced with reference
to the original sampling rate.
NOTE This applies for bimodal data compression.
EXAMPLE Original sampling rate 500 S/s (equivalent to a sample interval of 2 ms) is reduced to 125 S/s (equivalent
to a sample interval of 8 ms). The downsampling factor is then 4.
3.6
interpretive device
device (cart, computer) analysing the ECG signal
3.7
message
textual body of information
3.8
overreading
process whereby a cardiologist or a cardiology fellow reviews the computer-generated interpretation of an
ECG in order to verify the accuracy or to make changes to the interpretation text
NOTE An overread ECG is generally not the final clinically acceptable version for diagnosis and treatment. Usually,
the overreading process precedes the confirming process.
3.9
record
entire data file to be transmitted, including the ECG data and associated information, such as patient
identification, demographic and other clinical data
3.10
reference beat
reference/representative ECG cycle computed through any (but not specified) algorithm comprising the P,
QRS and the ST-T waves
3.11
residual data
remaining original ECG data after “proper” subtraction of the reference beat where the adjective “proper”
refers to accurate beat alignment
3.12
rhythm data
full original ECG data, or the decompressed and reconstructed ECG data at reduced resolution
NOTE Rhythm data is typically 10 s in length.
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ISO 11073-91064:2009(E)
3.13
section
aggregate of data elements related to one aspect of the electrocardiographic recording, measurement or
interpretation
3.14
universal statement codes
ECG interpretation codes
See Annex F.
NOTE See Glossary in Annex G for other technical terms related to this part of ISO 11073.
4 Abbreviations
AAMI American Association for the Advancement of Medical Instrumentation
AC Alternating current
AHA American Heart Association
AIM Advanced Informatics for Medicine Programmes of the European Commission Directorate
General XIII
ANSI American National Standards Institute
ASCII American Standard Code for Information Interchange
ASN.1 Abstract Syntax Notation One
AVM Amplitude Value Multiplier (see 5.8.3)
BS Backspace (control character)
CCITT International Telegraph and Telephone Consultative Committee
CEN Comité Européen de Normalisation/European Committee for Standardization
CR Carriage return (control character)
CRC Cyclic redundancy check
CSE Common standards for quantitative electrocardiography
DG Directorate General (of the European Commission)
EC European Community
ECG Electrocardiogram
ECU European currency unit (€)
EDIFACT Electronic Data Interchange for Administration, Commerce and Transport
EN Europäische Norm (European Standard)
ENV Europäische Norm Vorausgabe (European Pre-standard)
ESC Escape (control character)
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ISO 11073-91064:2009(E)
FF Form feed (control character)
HT Horizontal Tab (control character)
ICD International Classification of Diseases
ID Identification
IEC International Electrotechnical Commission
IEEE Institute of Electrical and Electronic Engineers
IMIA International Medical Informatics Association
ISO International Organization for Standardization
JIS Japanese Industrial Standard
LF Line feed (control character)
LSB Least significant bit
MSB Most significant bit
RMS Root mean square
SCP Standard Communications Protocol
SCP-ECG Standard Communications Protocol for Computerized Electrocardiography
TC Technical Committee
VCG Vectorcardiogram
VT Vertical tab (control character)
5 Definition of the data contents and format
5.1 General considerations
5.1.1 The data record which is to be interchanged shall be divided into different sections. The contents and
format of each of these sections are defined in this part of ISO 11073.
5.1.2 All text data (character strings) shall comply to the limited conformance requirements of
ISO/IEC 2022, described in Annex A. Latin-1 (ISO/IEC 8859-1) shall be the default character set.
5.1.3 All character strings shall be NULL terminated (not part of ISO/IEC 2022).
5.1.4 For all signed binary values 2's-complement coding shall be applied.
5.1.5 All single and multiple byte binary values are regarded as unsigned integers, if not otherwise
specified.
5.1.6 Binary values spanning more than 1 byte shall be transmitted in ascending order of significance (the
least significant byte is transmitted first, the most significant byte last).
5.1.7 Consecutive bytes are numbered from left to right (starting with 1). Bits of a byte are numbered from
right to left (0 = LSB, 7 = MSB).
5.1.8 The first byte in the record (i.e. the first byte of the checksum) is defined as Byte 1.
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ISO 11073-91064:2009(E)
5.1.9 ECG samples are indexed and numbered starting with sample number 1. Sample index 0 is not used
in this part of ISO 11073. The sample index is a ones-based 16-bit index. The first sample starts at time 0.
The second sample is at time (0 + 2) ms in case of 500 samples/s sampling rate.
5.1.10 Sections are numbered starting from 0 (the Pointer Section) to 32 767.
5.1.11 The term “Reference Beat” used in this part of ISO 11073 refers to an ECG complex that is chosen as
representative of a class of such complexes. No specific statistical meaning is implied by this term; for
example, it may be an averaged beat, a “Median Beat”, a selected or any other representative single cycle
taken from the total ECG recording. This “Reference Beat” does include the P-wave if present (not in case of
atrial fibrillation), the ST-T segment and the T wave of this beat.
An ECG may have multiple reference beats. The term “Beat type” used in this part of ISO 11073 refers to any
one of an ordered list of reference beats, starting with reference beat type 0 (zero). Reference beat type 0 is,
by definition, the reference beat used for classification of the ECG, and for reference beat subtraction, if
reference beat subtraction is used in compression. The ordering of the list of reference beats does not imply a
temporal sequence within the rhythm data.
The term “Rhythm Data” is used to indicate the ECG recording over the entire recording time, usually 10 s in
most recorders. A description of these terms and of the recommended data compression methodology,
including numerical examples and the methods for conformance testing on the minimum requirements of data
compression and signal distortion are given in Clause 6, Annex B and Annex C.
Reference Beat type 0 data in 5.8 are intended to be used for display, (re)analysis and, if reference beat
subtraction has been used for data compression, for Rhythm Data reconstruction.
5.1.12 All indexes or pointers to a field are defined in bytes and are ones-based (start at 1) if not otherwise
specified.
5.1.13 1 KByte = 1 024 bytes.
5.2 Specifications for the data structure
5.2.1 All sections shall start on an odd index (even offset) boundary. This implies that all sections shall
contain an even number of bytes. A padding byte has to be added to the end of any section containing an odd
number of bytes. Padding bytes shall always be set to NULL. Blocks of data within a section may contain
either odd or even numbers of bytes. Padding occurs only at the end of a section if needed.
5.2.2 All sections are given identification numbers. Section ID numbers 0 to 11 are currently defined in the
SCP-ECG protocol, numbers 12 to 127, as well as numbers above 1 024 are reserved for future use.
Numbers 128 to 1 023 are for manufacturer-specific sections. The combination of the manufacturer code
(see 5.4.3.1, tag 14) and section numbers 128 to 1 023 uniquely defines the content of the manufacturer-
specific sections. There are no specific rules for the layout and format of these sections. However, use of the
structure defined in 5.2.7 is recommended.
5.2.3 Inclusion of Sections 2, 4, 5, 7 to 11 (5.2.7 and 5.2.8) is optional. Any SCP-ECG data record shall
contain Section 0 (Pointers), Section 1 (Header), Section 3 (ECG Lead Definition) and Section 6 (Rhythm
Data). No other consistency checking among the presence of different sections is assumed. Specifically, if any
of the Sections 8, 9 or 11 is present, it is not assumed that all three shall be present.
5.2.4 The ECG record starts with a 6-byte record header, consisting of a 2-byte CRC followed by a 4-byte
record length. These are defined as follows:
1) the 2-byte cyclic redundancy check (CRC) is calculated as a CRC-CCITT, the algorithm of which is
described in E.5.5, and is calculated over the entire range starting with the first byte following the
CRC and ending with the last byte in the record;
2) the 4-byte record length denotes the number of bytes in the total record, including the 6 bytes of this
record header.
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ISO 11073-91064:2009(E)
5.2.5 Record overview:

Figure 1 — Record overview
5.2.6 The sequence
...