IEC 60601-2-51:2003

INTERNATIONAL IEC
STANDARD
60601-2-51
First edition
2003-02
Medical electrical equipment –
Part 2-51:
Particular requirements for safety,
including essential performance,
of recording and analysing single channel
and multichannel electrocardiographs
Appareils électromédicaux –
Partie 2-51:
Règles particulières de sécurité et
performances essentielles des électrocardiographes
enregistreurs et analyseurs mono et multi-canaux
Reference number
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INTERNATIONAL IEC
STANDARD
60601-2-51
First edition
2003-02
Medical electrical equipment –
Part 2-51:
Particular requirements for safety,
including essential performance,
of recording and analysing single channel
and multichannel electrocardiographs
Appareils électromédicaux –
Partie 2-51:
Règles particulières de sécurité et
performances essentielles des électrocardiographes
enregistreurs et analyseurs mono et multi-canaux
 IEC 2003  Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch  Web: www.iec.ch
PRICE CODE
Commission Electrotechnique Internationale
XC
International Electrotechnical Commission
Международная Электротехническая Комиссия
For price, see current catalogue

– 2 – 60601-2-51 © IEC:2003(E)
CONTENTS
FOREWORD . 4
INTRODUCTION .6
SECTION ONE – GENERAL
1 Scope and object . 7
2 Terminology and definitions. 8
4 General requirements for tests .11
6 Identification, marking and documents.12
SECTION TWO – ENVIRONMENTAL CONDITIONS
SECTION THREE – PROTECTION AGAINST ELECTRIC SHOCK HAZARDS
SECTION FOUR – PROTECTION AGAINST MECHANICAL HAZARDS
SECTION FIVE – PROTECTION AGAINST HAZARDS FROM UNWANTED
OR EXCESSIVE RADIATION
SECTION SIX – PROTECTION AGAINST HAZARDS OF IGNITION OF
FLAMMABLE ANAESTHETIC MIXTURES
SECTION SEVEN – PROTECTION AGAINST EXCESSIVE TEMPERATURES
AND OTHER SAFETY HAZARDS
SECTION EIGHT – ACCURACY OF OPERATING DATA AND PROTECTION
AGAINST HAZARDOUS OUTPUT
50 Accuracy of operating data.14
50.101 Automated measurements on ECGs (for ANALYSING ELECTROCARDIOGRAPHS) .14
50.102 Automated ECG interpretation (for ANALYSING ELECTROCARDIOGRAPHS) .19
51 Protection against hazardous output.23
51.101 LEADS .23
51.102 Input circuit .27
51.103 CALIBRATION.28
51.104 SENSITIVITY.29
51.105 Reduction of the effects of unwanted external voltages .29
51.106 Base-line .30
51.107 Distortion.32
51.108 Printing, electronic storage and transmission .34
51.109 Use with cardiac pacemakers .36
SECTION NINE – ABNORMAL OPERATION AND FAULT CONDITIONS;
ENVIRONMENTAL TESTS
SECTION TEN – CONSTRUCTIONAL REQUIREMENTS
56 Components and general assembly .37
56.7 BATTERIES .37
Appendix L (normative) References – Publications mentioned in this standard .43
Annex AA (informative) General guidance and rationale.44
Annex BB (informative) ELECTRODES, their positions, identifications and colour codes.51
Annex CC (informative) LEADS and their identification (other than described in 51.101).53
Annex DD (informative) Polarity of PATIENT LEADS (other than those specified in 51.101) .55
Annex EE (informative) Additional marking of electrodes.56
Annex FF (informative) Noise .58

60601-2-51 © IEC:2003(E) – 3 –
Annex GG (normative) Definitions and rules for the measurement
of ELECTROCARDIOGRAMS.60
Annex HH (normative) Calibration and test data sets .66
Annex II (informative) CTS test atlas .69
Bibliography .81
INDEX OF DEFINED TERMS .82
Figure 101 – Electrode position according to Frank (see Table 101).38
Figure 102 – Polarity of patient leads (see 51.101.1).38
Figure 103 – Test of weighting networks and input impedance (see 51.101.2.2 and 51.102.1) . 38
Figure 104 – Test of common mode rejection (see 51.105.1 and 51.106.4) .39
Figure 105 – Triangular waveforms for test E of Table 114 (see 51.107.1.1.1).40
Figure 106 – Input impulse signal (dashed trace) and cardiograph response
(continuous trace) (see 51.107.1.1.2) .40
Figure 107 – Circuit for test of linearity (see 51.107.2) .41
Figure 108 – Result of linearity test (see 51.107.2) .41
Figure 109 – Test of rectangular coordinates (see 51.108.4.1) .42
Table 101 – ELECTRODES and NEUTRAL ELECTRODES, their position, identification and
colour code .13
Table 102 – Offset voltage for ST and T amplitude reference values if the signals are
fed through a first order high pass FILTER with a TIME CONSTANT of 3,2 s.16
Table 103 – Acceptable mean differences and standard deviations for global intervals
and Q-, R-, S-durations on calibration and analytical ECGs .17
Table 104 – Acceptable mean differences and standard deviations for global durations
and intervals for biological ECGs .18
Table 105 – Disclosed changes of measurements caused by NOISE on ECGs according
to Table HH.3.18
Table 106 – Tabulation of test results .19
Table 107 – Format for disclosure of accuracy measures for diagnostic
interpretative statements .22
Table 108 – Format for disclosure of accuracy measures for rhythm interpretative statements. 23
Table 109 – Connection of ELECTRODES for a particular LEAD.24
Table 110 – LEADS and their identification (nomenclature and definition).24
Table 111 – LEAD networks for Goldberger and Wilson LEADS.26
Table 112 – LEAD network for Frank LEADS.27
Table 113 – Test of input impedance – Positions of LEAD SELECTOR, connection of LEAD
ELECTRODES and peak to valley deflection in mm with S1 open.28
Table 114 – Frequency response.32
Table HH.1 – Calibration and analytical ECGs.66
Table HH.2 – Data set for testing of measurement and wave recognition accuracy of
biological data – 100 ECGs of the CSE-study. .67
Table HH.3 – Data set for testing NOISE stability.67

– 4 – 60601-2-51 © IEC:2003(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEDICAL ELECTRICAL EQUIPMENT –
Part 2-51: Particular requirements for safety, including essential
performance, of recording and analysing single channel
and multichannel electrocardiographs
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International Organization
for Standardization (ISO) in accordance with conditions determined by agreement between the two
organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60601-2-51 has been prepared by subcommittee 62D: Electro-
medical equipment, of IEC technical committee 62: Electrical equipment in medical practice.
The text of this standard is based on the following documents:
FDIS Report on voting
62D/469/FDIS 62D/473/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
In this Particular Standard, the following print types are used:
• requirements, compliance with which can be tested, and definitions: roman type;
• notes, explanations, advice, introductions, general statements, exceptions and references: small roman type;
• test specifications: italic type;
•TERMS DEFINED IN CLAUSE 2 OF THE GENERAL STANDARD OR THIS PARTICULAR STANDARD:
SMALL CAPITALS.
60601-2-51 © IEC:2003(E) – 5 –
The committee has decided that the contents of this publication will remain unchanged until 2007.
At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
A bilingual version of this standard may be issued at a later date.

– 6 – 60601-2-51 © IEC:2003(E)
INTRODUCTION
This Particular Standard concerns additional safety of recording and analysing single
channel and multichannel electrocardiographic equipment. It amends and supplements
IEC 60601-1 (second edition, 1988), including its amendments 1 (1991) and 2 (1995)
hereinafter referred to as the General Standard. The requirements of this Particular Standard
take priority over those of the General Standard, entitled Medical electrical equipment – Part 1:
General requirements for safety.
A “General guidance and rationale” for the requirements of this Particular Standard is included
in Annex AA.
It is considered that a knowledge of the reasons for these requirements will not only facilitate
the proper application of the standard but will, in due course, expedite any revision
necessitated by changes in clinical practice or as a result of developments in technology.
However, this annex does not form part of the requirements of this Standard.
An asterisk (*) by a clause or subclause number indicates that some explanatory notes are
given in Annex AA.
60601-2-51 © IEC:2003(E) – 7 –
MEDICAL ELECTRICAL EQUIPMENT –
Part 2-51: Particular requirements for safety, including essential
performance, of recording and analysing single channel
and multichannel electrocardiographs
SECTION ONE – GENERAL
The clauses and subclauses of this section of the General Standard apply except as follows:
1 Scope and object
This clause of the General Standard applies except as follows:
*1.1 Scope
Addition:
This Particular Standard specifies requirements for the safety, including essential performance,
of RECORDING AND ANALYSING SINGLE CHANNEL AND MULTICHANNEL ELECTROCARDIOGRAPHS as
defined in 2.101, 2.111, 2.117, 2.123, 2.126, hereinafter referred to as EQUIPMENT. The
EQUIPMENT may be attended or unattended.
This Particular Standard complements IEC 60601-2-25 and its Amendment 1 (1999).
1.2 Object
Replacement:
The object of this Particular Standard is to establish particular requirements, in addition to the
requirements of IEC 60601-2-25, for the safety, including essential performance of RECORDING
AND ANALYSING SINGLE CHANNEL AND MULTICHANNEL ELECTROCARDIOGRAPHS.
These requirements shall apply particularly to
− RECORDING ELECTROCARDIOGRAPHS;
− ELECTROCARDIOGRAPHS which are part of other MEDICAL ELECTRICAL EQUIPMENT, for example
exercise testing systems, if this EQUIPMENT is used to record ECGs for diagnostic purposes;
− ELECTROCARDIOGRAPHS which are used as output units for ECG data base management
systems or ELECTROCARDIOGRAPHS which are used as output units located at other places
than the recording unit;
− ANALYSING ELECTROCARDIOGRAPHS, systems, and computing devices which by means of
electronic data processing and pattern recognition derive measurements (e.g. intervals and
amplitudes) and diagnostic statements from the ECG;
− those parts of PATIENT monitors or other specialised ELECTROCARDIOGRAPHS that are
capable of performing the functions of the ANALYSING ELECTROCARDIOGRAPHS.
This standard shall not apply to Holter ELECTROCARDIOGRAPHS, invasive electrocardiography,
PATIENT monitoring systems and high-resolution ELECTROCARDIOGRAPHS (e.g. HIS bundle
ELECTROCARDIOGRAPHS, ELECTROCARDIOGRAPHS for late potential detection) other than
stated above.
– 8 – 60601-2-51 © IEC:2003(E)
1.3 Particular Standards
Addition:
This Particular Standard refers to IEC 60601-1:1988, Medical electrical equipment – Part 1:
General requirements for safety, as amended by its Amendment 1 (1991) and Amendment 2
(1995), hereafter referred to as the General Standard, and to IEC 60601-2-25:1993, Medical
electrical equipment – Part 2-25: Particular requirements for the safety of electrocardiographs
and its Amendment 1 (1999).
The General Standard also takes into account IEC 60601-1-2:1993, Medical electrical
equipment – Part 1: General requirements for safety – 2. Collateral Standard: Electromagnetic
compatibility – Requirements and tests, and IEC 60601-1-4:1996, Medical electrical equipment
– Part 1: General requirements for safety – 4. Collateral Standard: Programmable electrical
medical systems.
The term “this Standard” is used to make reference to the General Standard and this Particular
Standard taken together.
The numbering of sections, clauses or subclauses of this Particular Standard corresponds with
that of the General Standard. The changes to the text of the General Standard are specified by
the use of the following words:
“Replacement” means that the clause or subclause of the General Standard is replaced
completely by the text of this Particular Standard.
“Addition” means that the text of this Particular Standard is additional to the requirements of
the General Standard.
“Amendment” means that the clause or subclause of the General Standard is amended as
indicated by the text of this Particular Standard.
Subclauses or figures which are additional to those of the General Standard are numbered
starting from 101, additional annexes are lettered AA, BB, etc., and additional items aa), bb), etc.
Where there is no corresponding section, clause or subclause in this Particular Standard, the
section, clause or subclause of the General Standard, although possibly not relevant, applies
without modification.
Where it is intended that any part of the General Standard, although possibly relevant, is not to be
applied, a statement to that effect is given in this Particular Standard.
The requirements of this Particular Standard take priority over those of the General Standard
and Collateral Standard mentioned above.
2 Terminology and definitions
This clause of the General Standard applies except as follows:
Additional definitions:
2.101
ANALYSING ELECTROCARDIOGRAPH
ELECTROCARDIOGRAPH capable of analysing heart action potentials, deriving measurements
from them and/or making interpretative statements. These may be also capable of
communicating ECGs and/or analysis results

60601-2-51 © IEC:2003(E) – 9 –
2.102
CALIBRATION (“CAL”)
facility enabling the CALIBRATION VOLTAGE and zero voltage to be recorded in place of the
ELECTROCARDIOGRAM
2.103
CALIBRATION VOLTAGE
voltage step recorded for amplitude CALIBRATION purposes
2.104
CENTRAL TERMINAL ACCORDING TO WILSON (CT)
terminal at the average potential of the R, L and F potentials
2.105
CHANNEL
hardware and/or software selection of a particular electrocardiographic LEAD for purposes of
display, recording, or transmission
2.106
COMMON MODE REJECTION
ability of the ELECTROCARDIOGRAPH including the PATIENT CABLE and LEAD ELECTRODES, high
frequency FILTERS, protection networks, LEAD networks, amplifier input, etc., to discriminate
between signals with differences between amplifier inputs (differential signal) and signals
common to amplifier inputs (common signal), in the presence of LEAD ELECTRODE impedance
imbalance
2.107
COMMON MODE DC OFFSET VOLTAGE
DC voltage appearing on LEAD ELECTRODES with respect to the NEUTRAL ELECTRODE resulting
from ELECTRODE-skin voltages
2.108
ECG RECORD
a registration (e.g. a hard copy write-out or a display) of an ECG signal including the associated
data such as date and time of the registration, name and identification of the PATIENT, etc.
2.109
EFFECTIVE RECORDING WIDTH
width of the recording paper within which the signal of a CHANNEL can be recorded according to
this performance standard
2.110
ELECTROCARDIOGRAM (ECG)
visible recording of heart action potentials as measured at the body surface (see also definition
2.108 ‘ECG RECORD’)
2.111
ELECTROCARDIOGRAPH (ecg)
MEDICAL ELECTRICAL EQUIPMENT and associated ELECTRODES intended for the production of
ELECTROCARDIOGRAMS for diagnostic purposes
2.112
ELECTRODE(S)
means (typically, an electrical sensor) in contact with a specified part of the body to detect
heart action voltage in combination with another means (see also Table 109). Both means
(electrical sensors) are connected to the ELECTROCARDIOGRAPH via a PATIENT CABLE

– 10 – 60601-2-51 © IEC:2003(E)
2.113
FILTER(S)
means, realized in hardware, firmware or software, to attenuate unwanted components in the
signal being recorded, e.g. muscle action voltages in ECG signal
2.114
LEAD WIRE(S)
cable(s) connected between ELECTRODE(s) and the ELECTROCARDIOGRAPH
2.115
LEAD(S)
Combination(s) of ELECTRODES and LEAD WIRES used for a certain ECG recording (see also
Table 110)
2.116
LEAD SELECTOR
system to select certain LEADS and CAL
2.117
MULTICHANNEL ELECTROCARDIOGRAPH
EQUIPMENT for the simultaneous recording of two or more ECG LEADS. This EQUIPMENT may also
provide facilities for phonocardiography and pulse recording, etc.
2.118
NEUTRAL ELECTRODE
reference point for differential amplifiers and/or interference suppression circuits. Any electro-
cardiographic LEAD is independent of the potential of this reference point
2.119
NOISE
unwanted signals of any frequency present in the ELECTROCARDIOGRAM
2.120
NORMAL SENSITIVITY
SENSITIVITY of 10 mm/mV
2.121
OVERLOAD TOLERANCE
maximum input-circuit voltage which does not alter the functioning of the ELECTROCARDIOGRAPH
2.122
PATIENT CABLE
multiwire cable and associated connector(s) to connect the ELECTRODES to the
ELECTROCARDIOGRAPH
2.123
RECORDING ELECTROCARDIOGRAPH
MEDICAL ELECTRICAL EQUIPMENT intended for the production of ECG RECORDS
2.124
REFERENCE POINT ACCORDING TO GOLDBERGER
reference point at an average potential of two limbs (e.g. average of L and F)
2.125
SENSITIVITY
ratio of the amplitude of a recording to the amplitude of the signal producing it, expressed
in mm/mV
60601-2-51 © IEC:2003(E) – 11 –
2.126
SINGLE CHANNEL ELECTROCARDIOGRAPH
EQUIPMENT for the recording of one ECG LEAD at a time
2.127
TEST
other designation for CAL
2.128
TIME CONSTANT
time taken for the output waveform step to decay to (37 %) of the initial amplitude. It is used
e
to define the low frequency response of an a.c. coupled amplifier to a d.c. step input
NOTE This definition is derived from a first order network.
2.129
WAVE RECOGNITION POINTS
reference points on the time axis of the ECG waveform for interval and amplitude measure-
ments on an ECG cycle:
• P-ONSET: beginning of the P-wave (atrial depolarisation);
• P-OFFSET: end of the P-wave;
• QRS-ONSET: beginning of the QRS-complex (ventricular depolarisation);
• QRS-OFFSET: end of the QRS-complex;
• T-OFFSET: end of the T-wave (end of ventricular repolarisation).
4 General requirements for tests
This clause of the General Standard applies except as follows:
4.6 Other conditions
Addition:
aa) Unless otherwise stated, tests shall be carried out with the accessories and the recording
materials specified by the manufacturer.
bb) EQUIPMENT with an INTERNAL ELECTRICAL POWER SOURCE shall be tested with the maximum
and minimum INTERNAL ELECTRICAL POWER SOURCE voltages specified by the manufacturer.
If necessary for the purpose of conducting this test, an external battery of specified
minimum or maximum voltage may be connected.
cc) The values used in test circuits shall have at least an accuracy as given below:
– resistors ±2 %
– capacitors ±10 %
– inductors ±10 %
– test voltages ±1 %
– 12 – 60601-2-51 © IEC:2003(E)
4.11 Sequence
Addition:
Tests called for in this Particular Standard shall be performed after the tests of the General
Standard and the tests of IEC 60601-2-25 and its Amendment 1 (1999).
6 Identification, marking and documents
This clause of the General Standard applies except as follows:
*6.1 Marking on the outside of EQUIPMENT or EQUIPMENT parts
Addition:
aa) In order to minimize the possibility of incorrect connections, the PATIENT CABLE shall be
permanently marked with one of the identifiers (ELECTRODE identifier and/or colour code)
specified in Table 101;
bb) The PATIENT CABLE to EQUIPMENT connector shall be so constructed or marked as to enable
the USER to identify the EQUIPMENT to which the PATIENT CABLE is intended to be connected.
6.8.2 Instructions for use
Addition:
aa) Manufacturer shall disclose the following in the ACCOMPANYING DOCUMENTS:
– the way amplitude values for the P-, QRS-, ST- and T-waves are determined as required in
50.101.2;
– the way isoelectric segments within the QRS complex are treated as required in 50.101.3;
– the criteria applied in the EQUIPMENT for acceptance of minimum waves and stability of the
measurements in the presence of NOISE as required in 50.101.4;
– the intended use of the analysing electrocardiograph as required in 50.102.2;
– the cardiac abnormalities of low prevalence that were not included in the test contour
diagnostic data base as required in 50.102.3.1;
– the ECG categories and the number of ECGs tested in these categories as required in
50.102.3.2 (see also 50.102.3.1);
– accuracy measures for diagnostic interpretative statements, non-ECG means for validation
of cardiac diagnosis and the group statistics of patient demographics (such as age, gender,
race etc.) as required in 50.102.3.2;
– the cardiac rhythms of low prevalence that were not included in the test rhythm ECG
database as required in 50.102.4.1;
– the ECG categories and the number of ECGs tested in these categories as required in
50.102.4.2 (see also 50.102.4.1);
– accuracy measures for rhythm interpretative statements and the group statistics of patient
demographics (such as age, gender, race etc.) as required in 50.102.4.2;
– the instructions for regular testing of the SENSITIVITY, when the CALIBRATION does not check
the overall SENSITIVITY as required in 51.103.2;
– if the ELECTROCARDIOGRAPH must have FILTERS set, the arrangements to pass the distortion
test, and the effect of these FILTER settings on ECG signal distortion as required in 51.109.1;
– the minimum length of time that the ELECTROCARDIOGRAPH will conform to the requirements
of this Particular Standard under the conditions required in Clause 56.

60601-2-51  IEC:2003(E)           – 13 –
Table 101 – ELECTRODES and NEUTRAL ELECTRODES, their position, identification and colour code
CODE 1 (usually European) CODE 2 (usually American)
System Position on body surface
ELECTRODE Colour code ELECTRODE Colour code
identifier identifier
R Red RA White Right arm
L Yellow LA Black Left arm
Limb
F Green LL Red Left leg
C White V Brown Single movable chest ELECTRODE
C1 White/red V1 Brown/red Fourth intercostal space at right border of sternum
C2 White/yellow V2 Brown/yellow Fourth intercostal space at left border of sternum
Chest
C3 White/green V3 Brown/green Fifth rib between C2 and C4
according to
C4 White/brown V4 Brown/blue Fifth intercostal space on left midclavicular line
Wilson
C5 White/black V5 Brown/orange Left anterior axillary line at the horizontal level of C4
C6 White/violet V6 Brown/violet Left midaxillary line at the horizontal level of C4
I Orange/red At the right midaxillary line a)
I Light blue/red
E Light blue/yellow E Orange/yellow At the front midline a)
C Light blue/green C Orange/green Between front midline and left midaxillary
Position
line at an angle of 45 degrees a)
according to
A Light blue/brown A Orange/brown At the left midaxillary line a)
Frank (see
a
M Light blue/black M Orange/black At the back midline a)
Figure 1)
H Light blue/violet H Orange/violet On the back of the neck
F Green F Red On the left leg
N Black RL Green Right leg (NEUTRAL)
NOTE Additional recommendations are given in Annex BB and Annex EE.
a
Located at the transverse level of the ventricles, if known, or otherwise at the fifth intercostal space

– 14 – 60601-2-51 © IEC:2003(E)
SECTION TWO – ENVIRONMENTAL CONDITIONS
The clauses and subclauses of this section of the General Standard (and of IEC 60601-2-25
including its Amendment 1 (1999)) apply.
SECTION THREE – PROTECTION AGAINST ELECTRIC SHOCK HAZARDS
The clauses and subclauses of this section of the General Standard (and of IEC 60601-2-25
including its Amendment 1 (1999)) apply.
SECTION FOUR – PROTECTION AGAINST MECHANICAL HAZARDS
The clauses and subclauses of this section of the General Standard (and of IEC 60601-2-25
including its Amendment 1 (1999)) apply.
SECTION FIVE – PROTECTION AGAINST HAZARDS FROM UNWANTED
OR EXCESSIVE RADIATION
The clauses and subclauses of this section of the General Standard (and of IEC 60601-2-25
including its Amendment 1 (1999)) apply.
SECTION SIX – PROTECTION AGAINST HAZARDS OF IGNITION OF FLAMMABLE
ANAESTHETIC MIXTURES
The clauses and subclauses of this section of the General Standard (and of IEC 60601-2-25
including its Amendment 1 (1999)) apply.
SECTION SEVEN – PROTECTION AGAINST EXCESSIVE TEMPERATURES AND
OTHER SAFETY HAZARDS
The clauses and subclauses of this section of the General Standard (and of IEC 60601-2-25
including its Amendment 1 (1999)) apply.
SECTION EIGHT – ACCURACY OF OPERATING DATA AND PROTECTION
AGAINST HAZARDOUS OUTPUT
The clauses and subclauses of this section of the General Standard apply except as follows:
50 Accuracy of operating data
Addition:
*50.101 Automated measurements on ECGs (for ANALYSING ELECTROCARDIOGRAPHS)
If automated measurements are provided by the ELECTROCARDIOGRAPH, their accuracy shall
meet the requirements as stated in this section. If the stated requirement(s) is (are) only for
disclosure, the manufacturer shall disclose the required performance accuracy in the
ACCOMPANYING DOCUMENTS.
50.101.1 Standard databases to evaluate accuracy of automated ECG measurements
50.101.1.1 Standard databases to evaluate accuracy of amplitude measurements
Calibration and analytical ECGs of Table HH.1 of Annex HH shall be used to evaluate the
accuracy of amplitude measurements (see 50.101.2).

60601-2-51 © IEC:2003(E) – 15 –
50.101.1.2 Standard databases to evaluate the accuracy of absolute interval and wave
duration measurements
Calibration and analytical ECGs of Table HH.1 of Annex HH shall be used to evaluate the
accuracy of absolute interval and wave duration measurements (see 50.101.3.1).
50.101.1.3 Standard databases to evaluate the accuracy of interval measurements on
biological ECGs
ECGs of Table HH.2 of Annex HH shall be used to evaluate the accuracy of interval
measurements on biological ECGs (see 50.101.3.2).
50.101.1.4 Standard databases to evaluate stability of measurements against NOISE
ECGs of Table HH.3 of Annex HH shall be used to evaluate the stability of measurements
against NOISE (see 50.101.4).
*50.101.2 Requirements for amplitude measurements
The manufacturer shall disclose in the ACCOMPANYING DOCUMENTS in which way amplitude
values for the P-, QRS-, ST- and T-waves are determined.
If an ANALYSING ELECTROCARDIOGRAPH provides measurements, their accuracy shall be tested.
Amplitude measurements given for P, Q, R, S, ST and T shall not deviate from the reference
values by more than ±25 µV for amplitudes ≤500 µV or by more than 5 % for amplitudes
>500 µV.
The calibration and analytical ECGs listed in Table HH.1 of Annex HH shall be fed into the
ELECTROCARDIOGRAPH under test and shall be recorded for at least 8 s (see guidelines at the
end of Annex AA for inputting ECGs). The differences between the amplitude measurements
and the reference values for LEADS I, II, V1, ., V6 shall be determined for all provided P-, Q-,
R-, S-, ST- and T-waveforms.
ECGs are fed into the system after digital to analogue
If the calibration and analytical
conversion via the ELECTRODE cables (see guidelines at the end of Annex AA for inputting
ECGs), the tests shall be performed five times. If the ELECTROCARDIOGRAPH can be tested with
digital input of calibration and analytical ECGs, the test needs to be performed only once. The
differences between measurements and reference values shall be calculated either from the
single test or from the mean values of the five tests.
If there are obvious fiducial point (P-, QRS-ONSET/OFFSET and T-OFFSET) errors, exclude the
differences in the affected amplitude measurements. Exclusion of differences resulting from not
more than two fiducial point errors shall be allowed. The difference for each remaining
amplitude measurement shall not deviate from the reference value by more than ±25 µV for
reference values ≤500 µV, or by more than 5 % or ±40 µV (whichever is greater) for reference
values >500 µV.
NOTE For the calibration ECGs CAL20100, CAL20200, and CAL20260, an offset voltage for ST and T amplitudes
of approximately 20 µV is to be considered if the signals are fed through a first order high pass FILTER (e.g. an
analogue amplifier) with a TIME CONSTANT of 3,2 s as shown in Table 102.

– 16 – 60601-2-51 © IEC:2003(E)
Table 102 – Offset voltage for ST and T amplitude reference values if the signals are fed
through a first order high pass FILTER with a TIME CONSTANT of 3,2 s
Offset voltages
µV
Calibration ECG
LEADS I, II, V1 . V6 LEAD III LEAD aVR LEADS aVL, aVF
CAL05000 0 0 0 0
CAL10000 0 0 0 0
CAL15000 0 0 0 0
CAL20000 0 0 0 0
CAL20002 0 0 0 0
CAL30000 0 0 0 0
CAL20100 −−−−20 0 +20 −−−−10
CAL20200 20 0 −−−−20 10
CAL20260 20 0 −−−−20 10
ANE20000
ANE20001
ANE20002
NOTE If, due to the artificial nature of the CAL ECGs, the ELECTROCARDIOGRAPH suppresses printing of
measurements, then the measurement values that are obtained but not printed shall be used for these tests.

50.101.3 Requirements for interval measurements
The manufacturer shall disclose in the ACCOMPANYING DOCUMENTS in which way the isoelectric
segments within the QRS complex are treated: whether they are included into or excluded from
the Q-, R- or S-waves. He shall specifically explain whether isoelectric parts (I-wave) after
global QRS-ONSET or before global QRS-OFFSET (K-wave) are included in the duration
measurement of the respective adjacent waveform.
If the measurements are provided for the ECG RECORD, their accuracy shall be tested as
follows.
*50.101.3.1 Requirements for absolute interval and wave duration measurements
These measurements shall be derived from the global interval and the wave duration
measurements (see Table HH.1) on the calibration and analytical ECGs. Acceptable tolerances
for the mean differences of global durations and intervals and Q-, R- and S-duration
measurements are given in Table 103.

60601-2-51 © IEC:2003(E) – 17 –
Table 103 – Acceptable mean differences and standard deviations for
global intervals and Q-, R-, S-durations on calibration and analytical ECGs
All dimensions in ms
Acceptable Acceptable
Measurement
mean difference standard deviation
P-duration ±10 8
PQ-interval ±10 8
QRS-duration ±65
QT-interval ±12 10
Q-duration ±65
R-duration ±65
S-duration ±65
The calibration and analytical ECGs listed in Table HH.1 shall be fed into the electrocardiograph
under test; simultaneous acquisition of all LEADS is assumed.
If the calibration and analytical ECGs are fed into the system after digital to analogue
conversion via the ELECTRODE cables (see guidelines at the end of Annex AA for inputting
ECGs), the tests shall be performed five times. If the ELECTROCARDIOGRAPH can be tested with
digital input of the test ECGs, the test need be performed only once. The differences between
measurements and reference values shall be calculated either from the single test or from the
mean values of the five tests.
For each of the global measurements (P-duration, PQ-interval, QRS-duration, and QT-interval)
there will be 16 difference numbers. If there are obvious fiducial point (P-, QRS-ONSET/OFFSET
and T-OFFSET) errors, exclude the differences in the affected global and individual LEAD
intervals. Exclusion of differences resulting from not more than two fiducial point errors shall be
allowed. From the remaining differences, remove the two largest deviations from the mean
(outliers) for each measurement. The means and standard deviations of the remaining
differences are computed and shall not exceed the tolerances given in Table 103.
For each of the individual LEAD measurements (Q-, R-, and S-durations) compute the
differences for LEADS I, II, V1 . V6 (if the wave is present) for all the calibration and analytical
ECGs listed in Table HH.1. Exclude differences resulting from fiducial point errors as described
above. From the remaining differences remove the two largest deviations from the mean
(outliers) for each measurement. The means and standard deviations of the remaining
differences are computed and shall not exceed the tolerances given in Table 103.
*50.101.3.2 Requirements for interval measurements on biological ECGs
One hundred (100) real test ECGs (MA1_ or MO1_ series from the CSE study, listed in Table
HH.2) shall be fed into the ELECTROCARDIOGRAPH (either digitally or after D/A-conversion) and
analysed by the system under test (see guidelines at the end of Annex AA for inputting ECGs).
Measurement results shall be analysed according to the following rules.
If there are obvious fiducial point (P-, QRS-ONSET/OFFSET and T-OFFSET) errors, exclude the
differences in the affected global intervals. Exclusion of differences resulting from not more
than four fiducial point errors shall be allowed. From the remaining differences, remove the four
largest deviations from the mean (outliers) for each measurement. The means and standard
deviations of the remaining differences are computed and shall not exceed the tolerances given
in Table 104.
– 18 – 60601-2-51 © IEC:2003(E)
Table 104 – Acceptable mean differences and standard deviations
for global durations and intervals for biological ECGs
Dimensions in ms
Acceptable Acceptable
Global measurement
mean difference standard deviation
P-duration ±10 15
PQ-interval 10
±10
QRS-duration ±10 10
QT-interval 30
±25
*50.101.4 Disclosure requirements for stability of measurements against NOISE
The manufacturer shall disclose in the ACCOMPANYING DOCUMENTS the criteria applied in the
EQUIPMENT for acceptance of minimum waveforms.
If measurements are provided, the stability of the measurements in the presence of NOISE shall
be disclosed in the ACCOMPANYING DOCUMENTS according to Table 105.
Table 105 – Disclosed changes of measurements caused by
NOISE on ECGs according to Table HH.3
Disclosed differences
Global Type of added
Standard
Mean
measurement NOISE
deviation
ms ms
P-duration High frequency
P-duration Line frequency
P-duration Base-line
QRS-duration High frequency
QRS-duration Line frequency
QRS-duration Base-line
QT-interval High frequency
QT-interval Line frequency
QT-interval Base-line
The ten ELECTROCARDIOGRAMS listed in Table HH.3, shall be fed into the ELECTROCARDIOGRAPH
under test:
a) without NOISE;
b) with 25 µV r.m.s. high frequency NOISE generated as specified in Clause HH.3;
c) with 50 µV peak to valley 50/60 Hz sinusoidal line frequency NOISE;
d) with 1 mV peak to valley 0,3 Hz sinusoidal base-line NOISE.
If the biological ECGs are fed into the system after digital to analogue conversion via the
ELECTRODE cables, the tests shall be performed five times (see guidelines at the end
of Annex AA for inputting ECGs). If the ELECTROCARDIOGRAPH can be tested with digital input of
biological ECGs the test need be performed only once. The differences between measurements
and reference values shall be calculated either from the single test or from the mean values of
the five tests.
60601-2-51 © IEC:2003(E) – 19 –
For each NOISE level the differences of measurements according to Table 105 between the
NOISE-free ECGs and the ECGs with NOISE shall be determined and their mean value and
standard deviation shall be calculated. The two largest deviations from the mean (outliers) shall
be eliminated before calculation of mean and standard deviation of differences.
*50.102 Automated ECG interpretation (for ANALYSING ELECTROCARDIOGRAPHS)
If automated ECG interpretation is provided by the ELECTROCARDIOGRAPH, the manufacturer
shall disclose the required interpretation accuracy measures in the ACCOMPANYING DOCUMENTS
as stated in this subclause.
50.102.1 Definition of accuracy measures for automated ECG interpretation
For the purpose of this document, four key accuracy measures are explained below.
It is assumed that the true diagnosis for a PATIENT is known (“truth”). The ECG interpretation
(classification) is called “Test”. The following designations are applied to characterise the
performance of a test (respectively of an ECG interpretation system), see Table 106:
a) a “Normal” correctly classified as “Normal” is called “True normal” (TN);
b) a “Normal” incorrectly classified as “Pathologic” is called “False pathologic” (FP);
c) a “Pathologic” incorrectly classified ’as “Normal” is called “False normal” (FN);
d) a “Pathologic”
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