ISO 14708-3:2008

INTERNATIONAL ISO
STANDARD 14708-3
First edition
2008-11-15
Implants for surgery — Active
implantable medical devices —
Part 3:
Implantable neurostimulators
Implants chirurgicaux — Dispositifs médicaux implantables actifs —
Partie 3: Neurostimulateurs en implant

Reference number
©
ISO 2008
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©  ISO 2008
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ii © ISO 2008 – All rights reserved

Contents Page
Foreword. v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Symbols and abbreviated terms . 3
5 General requirements for non-implantable parts . 3
6 Requirements for particular active implantable medical devices . 3
7 General arrangement of the packaging. 6
8 General markings for active implantable medical devices . 6
9 Markings on the sales packaging . 6
10 Construction of the sales packaging. 7
11 Markings on the sterile pack . 8
12 Construction of the non-reusable pack. 8
13 Markings on the active implantable medical device . 9
14 Protection from unintentional biological effects caused by the active implantable medical
device. 9
15 Protection from harm to the patient or user caused by external physical features of the
active implantable medical device. 10
16 Protection from harm to the patient caused by electricity. 10
17 Protection from harm to the patient caused by heat . 11
18 Protection from ionizing radiation released or emitted from the active implantable
medical device . 11
19 Protection from unintended effects caused by the device. 11
20 Protection of the device from damage caused by external defibrillators. 12
21 Protection of the device from changes caused by high-power electrical fields applied
directly to the patient. 12
22 Protection of the active implantable medical device from changes caused by
miscellaneous medical treatments . 12
23 Protection of the active implantable medical device from mechanical forces . 12
24 Protection of the active implantable medical device from damage caused by electrostatic
discharge . 13
25 Protection of the active implantable medical device from damage caused by atmospheric
pressure changes . 13
26 Protection of the active implantable medical device from damage caused by temperature
changes . 13
27 Protection of the active implantable medical device from electromagnetic non-ionizing
radiation. 13
28 Accompanying documentation. 21
[8]
Annex AA (informative) Relationship between the fundamental principles in ISO/TR 14283 and
the clauses of this part of ISO 14708 . 23
Annex BB (informative) Relationship between the clauses of this part of ISO 14708 and the
fundamental principles listed in Annex AA. 33
Annex CC (informative) Rationale. 35
Bibliography . 44

iv © ISO 2008 – All rights reserved

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 14708-3 was prepared by Technical Committee ISO/TC 150, Implants for surgery, Subcommittee SC 6,
Active implants.
ISO 14708 consists of the following parts, under the general title Implants for surgery — Active implantable
medical devices:
⎯ Part 1: General requirements for safety, marking and for information to be provided by the manufacturer
⎯ Part 2: Cardiac pacemakers
⎯ Part 3: Implantable neurostimulators
⎯ Part 4: Implantable infusion pumps
Introduction
This part of ISO 14708 specifies particular requirements for active implantable medical devices intended for
electrical stimulation of the central or peripheral nervous system, to provide basic assurance of safety for both
patients and users. It amends and supplements ISO 14708-1:2000, hereinafter referred to as ISO 14708-1.
The requirements of this part of ISO 14708 take priority over those of ISO 14708-1.
Devices that use electricity to stimulate the nervous system are commonly called neurostimulators. They
produce controlled electrical pulses that are delivered through electrodes in contact with a specific target area.
Whether or not a neurostimulator is totally or partially implantable, a lead or extension is usually required to
convey stimulation pulses from a form of pulse generator to the electrodes, although newer forms of device
might not utilize leads or extensions. An external programmer might be used to adjust device parameters.
Currently, several types of neurostimulators exist for treating the central or peripheral nervous system. This
part of ISO 14708 is intended to apply to these neurostimulator types regardless of therapy. (See Clause 3 for
device type definitions used throughout this part of ISO 14708.)
This part of ISO 14708 is relevant to all parts and accessories of implantable neurostimulators, including
programmers, trial screeners, software, and technical manuals. Not all parts or accessories might be intended
to be totally or partially implanted, but there is a need to specify some requirements of non-implantable parts
and accessories if they could affect the safety or performance intended by the manufacturer.
Requirements for physiologic sensing functions of implantable neurostimulators are not included in this edition
of this part of ISO 14708 but might be considered in future editions.
Within this part of ISO 14708 the following terms are used to amend and supplement ISO 14708-1:
“Replacement”: the clause of ISO 14708-1 is replaced completely by the text of this part of ISO 14708.
“Addition”: the text of this part of ISO 14708 is additional to the requirements of ISO 14708-1.
“Amendment”: the clause of ISO 14708-1 is amended as indicated by the text of this part ISO 14708.
“Not used”: the clause of ISO 14708-1 is not applied in this part ISO 14708.
Subclauses, figures, or tables that are additional to those of ISO 14708-1 are numbered starting from 101;
additional annexes are lettered AA, BB, etc.

vi © ISO 2008 – All rights reserved

INTERNATIONAL STANDARD ISO 14708-3:2008(E)

Implants for surgery — Active implantable medical devices —
Part 3:
Implantable neurostimulators
1 Scope
This part of ISO 14708 is applicable to active implantable medical devices intended for electrical stimulation of
the central or peripheral nervous system.
This part of ISO 14708 is also applicable to all non-implantable parts and accessories of the devices as
defined in Clause 3.
The tests that are specified in this part of ISO 14708 are type tests intended to be carried out on a sample of a
device to show compliance, and are not intended to be used for the routine testing of manufactured products.
NOTE This part of ISO 14708 is not intended to apply to non-implantable neurostimulation devices. However, it does
apply to devices intended to be used as trial screeners because of their close affiliation with implantable neurostimulators.
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 14708-1, Implants for surgery — Active implantable medical devices — Part 1: General requirements for
safety, marking and for information to be provided by the manufacturer
IEC 60601-1:2005, Medical electrical equipment — Part 1: General requirements for basic safety and
essential performance
IEC 60601-1-2:2007, Medical electrical equipment — Part 1-2: General requirements for basic safety and
essential performance — Collateral standard: Electromagnetic compatibility — Requirements and tests
IEC 61000-4-3:2002, Electromagnetic compatibility (EMC) — Part 4-3: Testing and measurement
techniques — Radiated, radio-frequency, electromagnetic field immunity test
ANSI/AAMI PC69:2000, Active implantable medical devices — Electromagnetic compatibility — EMC test
protocols for implantable cardiac pacemakers and implantable cardioverter defibrillators
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 14708-1 and the following apply.
3.101
implantable neurostimulator
INS
active implantable medical device intended for electrical stimulation of the central or peripheral nervous
system
NOTE For purposes of this part of ISO 14708, an implantable neurostimulator can be a single article, or a system
consisting of a set of components and accessories which interact to achieve the performance intended by the
manufacturer. Not all of these components or accessories might be required to be partially or totally implanted, e.g.
programmers, screeners and RF transmitters.
3.102
implantable pulse generator
IPG
implantable part of a particular type of implantable neurostimulator, typically consisting of a power source and
electronic circuit, which produces a stimulation voltage or current pulse
NOTE The complete neurostimulator includes a means for conveying the output pulse to the stimulation site.
3.103
RF transmitter
non-implantable part of a particular type of implantable neurostimulator, typically consisting of a power source
and electronic circuit, which produces an electrical output pulse transmitted through an antenna to an
implanted RF receiver
3.104
RF receiver
implantable part of a particular type of implantable neurostimulator which converts an electrical pulse received
from an external RF transmitter into a stimulation voltage or current pulse
3.105
trial screener
non-implantable neurostimulator, used during a trial period of stimulation, typically consisting of a power
source and electronic circuit, which produces a stimulation voltage or current pulse conveyed to the
stimulation site through a lead or leads
NOTE Although a medical device in its own right, a screener is considered by this part of ISO 14708 as an accessory
to an implantable neurostimulator.
3.106
projected service life
period after implantation when the implantable neurostimulator remains within stated specifications and
characteristics
3.107
DUT
device under test, including conductive leads
3.108
essential performance
performance necessary to achieve freedom from unacceptable risk
NOTE For guidance on essential performance concepts, see IEC 60601-1.
2 © ISO 2008 – All rights reserved

4 Symbols and abbreviated terms
This clause of ISO 14708-1 applies.
5 General requirements for non-implantable parts
This clause of ISO 14708-1 applies except as follows.
Addition:
NOTE 3 This clause applies to RF transmitters, trial screeners, and programmers, for example. A percutaneous lead,
such as might be used with screeners, is considered to be an implantable part.
6 Requirements for particular active implantable medical devices
Additional subclauses:
6.101 Measurement of stimulation pulse characteristics
This subclause describes a uniform method of measurement for certain stimulation pulse characteristics
(amplitude, pulse width, pulse rate and pulse shape). The related specifications and characteristics stated by
the manufacturer in the accompanying documentation (see 28.8) shall correspond with the results obtained in
accordance with this method.
If the neurostimulator has multiple channels or output modes (e.g. bipolar or unipolar), the characteristics of
each channel or mode shall be determined. Consideration shall be given to all states of operation,
i.e. channels or modes operating individually or simultaneously.
Test conditions and device settings applicable to the stimulation pulse characteristics stated in the
accompanying documentation shall also be stated (see 28.8).
NOTE 1 Test conditions refer, for example, to ambient temperature and any special circumstances that existed during
the measurements. Device settings refer, for example, to the rate and pulse width values that were set during the
amplitude measurement.
The test sample shall be representative of production units, be in normal working condition, and shall not have
reached the elective replacement indication (see 19.2).
⎯ Method: The pulse generator (i.e. IPG, RF receiver, trial screener) shall be connected to a load resistor,
R , and test equipment as shown in Figure 101. Resister values for R shall be determined by the
L L
manufacturer based on appropriate tissue impedances for use of the product. Measurements shall be
replicated to characterize operation at minimum, typical and maximum load impedances. More complex
impedances may be used if they better represent actual use. In addition, the measurements shall be
performed using a nominal impedance, R , of 499 Ω ± 1 %. The load impedances used to obtain the
L
stimulation pulse characteristics stated in the accompanying documentation (see 28.8) shall also be
stated.
Points A and B, as shown in Figure 101, represent either the direct electrical output of the pulse generator
or the electrodes at the distal end of a lead (or lead-extension combination), if applicable. The
manufacturer shall unequivocally state the configuration(s) that are applicable to the stimulation pulse
characteristics stated in the accompanying documentation (see 28.8).
NOTE 2 Configuration refers to the point of measurement and to the model mix of pulse generator, and leads and
extensions, (if applicable).
While performing these measurements, the pulse shapes associated with each channel shall be
characterized and described in the accompanying documentation (see 28.8). Any variations in pulse
shapes, between channels, output modes, states of operation or load conditions, shall also be described.
The measurement accuracy of the test set-up shall be within ± 5 %. Test equipment and test sample shall
be at room temperature.
Key
1 oscilloscope
2 channel 1
3 trigger
4 pulse generator
5 load (as specified)
Figure 101 — Test set-up for measuring stimulation pulse characteristics

The pulse amplitude shall be measured from the base (just prior to the pulse transition) to the peak of the
pulse as shown in Figure 102. The result shall be expressed in volts or milliamperes, as appropriate. In
addition, other units may be used at the manufacturer’s discretion.

Key
1 amplitude
Figure 102 — Measurement of pulse amplitude

4 © ISO 2008 – All rights reserved

The pulse width shall be measured between the points on the pulse equal to one-half of the peak pulse
amplitude as shown in Figure 103. The result shall be expressed in microseconds. In addition, other units may
be used at the manufacturer’s discretion.

Key
1 pulse width (at ½ amplitude point)
Figure 103 — Measurement of pulse width
The pulse rate shall be determined by measuring the interval from the leading edge of one pulse to the
leading edge of the next pulse from the same point on the pulse used to measure pulse width
(see Figure 104). The actual rate is calculated from the reciprocal of the interval measurement. The result
shall be expressed in Hertz (Hz). In addition, other units may be used at the manufacturer’s discretion.

Key
1 pulse interval (at ½ amplitude point)
Figure 104 — Measurement of pulse interval to determine rate
6.102 Measurement of lead or extension d.c. resistance
This subclause describes a uniform method of measurement for lead or extension d.c. resistance. The related
specifications and characteristics stated by the manufacturer in the accompanying documentation (see 28.8)
shall correspond with the results obtained in accordance with this method.
If the lead or extension has multiple conductors, the d.c. resistance of each conductor shall be determined.
Test conditions applicable to the lead or extension d.c. resistance stated in the accompanying documentation
shall also be stated (see 28.8).
NOTE Test conditions refer, for example, to ambient temperature and any special circumstances that existed during
the measurements.
The test sample shall be representative of production units and be in normal working condition.
⎯ Method: The d.c. resistance of lead and extension conductors shall be measured by applying a four
terminal ohmmeter (offset compensated) between the proximal and distal end of each conductive element.
The results shall be expressed in ohms. In addition, other units may be used at the manufacturer’s
discretion.
The measurement accuracy of the test setup shall be within ± 5 %. Test equipment and test sample shall
be at room temperature.
7 General arrangement of the packaging
This clause of ISO 14708-1 applies.
8 General markings for active implantable medical devices
This clause of ISO 14708-1 applies except as follows.
8.2
Addition:
NOTE For leads that are not intended to be implanted and are used only temporarily, this requirement does not apply.
Additional subclauses:
8.101 If special handling measures have to be taken during transport, the transport packaging shall be
[1] [2]
marked accordingly (see ISO 780 or ISO 15223 ).
Compliance shall be checked by inspection.
8.102 The permissible environmental conditions for transport shall be marked on the outside of the transport
packaging.
Compliance shall be checked by inspection.
9 Markings on the sales packaging
This clause of ISO 14708-1 applies except as follows.
9.4
Addition:
Specific additional information shall be provided for the following components:
a) Implantable pulse generator (IPG) and trial screener
⎯ number of electrodes and channels,
⎯ if the output is constant voltage or constant current,
⎯ any additional information and relevant characteristics, as necessary, to identify the device.
b) Lead
⎯ type of lead (e.g. surgical, percutaneous, cuff, CNS, peripheral),
⎯ number of electrodes per lead,
⎯ lead length (in centimetres),
⎯ any additional information and relevant characteristics, as necessary, to identify the device.
6 © ISO 2008 – All rights reserved

c) Extension
⎯ type of extension (e.g. low profile, bifurcated),
⎯ number of electrodes per extension,
⎯ extension length (in centimetres),
⎯ any additional information and relevant characteristics, as necessary, to identify the device.
d) RF receiver
⎯ number of electrodes and channels,
⎯ if the output is constant voltage or constant current
⎯ maximum recommended implant depth,
⎯ a means of identifying the corresponding RF transmitter,
⎯ a means of identifying the corresponding lead, if not permanently attached,
⎯ any additional information and relevant characteristics, as necessary, to identify the device.
e) RF transmitter
⎯ number of channels,
⎯ maximum recommended transmission distance,
⎯ a means of identifying the corresponding RF receiver,
⎯ any additional information and relevant characteristics, as necessary, to identify the device.
Additional subclause:
9.101 The sales packaging shall, when appropriate, bear an indication that the contents are intended for
single use only.
Compliance shall be checked by inspection.
10 Construction of the sales packaging
This clause of ISO 14708-1 applies except as follows.
10.3
Amendment:
The test is replaced by subclause 7.1.3 b) of IEC 60601-1:2005.
NOTE Removable stickers (e.g. temporary stickers used in the manufacturing process), which provide
supplementary information exceeding the information specified in Clause 9, need not be subjected to this test.
11 Markings on the sterile pack
This clause of ISO 14708-1 applies except as follows.
Additional subclause:
11.101 The sterile pack shall bear specific additional information for the following components:
a) Implantable pulse generator (IPG)
⎯ number of electrodes and/or channels,
⎯ if the output is constant voltage or constant current,
⎯ maximum recommended implant depth, if applicable,
⎯ any additional information and relevant characteristics, as necessary, to identify the device.
b) Lead
⎯ type of lead (e.g. surgical, percutaneous, cuff, CNS, peripheral),
⎯ number of electrodes per lead,
⎯ lead length (in centimetres),
⎯ any additional information and relevant characteristics, as necessary, to identify the device.
c) Extension
⎯ type of extension (e.g. low profile, bifurcated),
⎯ number of electrodes per extension,
⎯ extension length (in centimetres),
⎯ any additional information and relevant characteristics, as necessary, to identify the device.
d) RF receiver
⎯ maximum recommended implant depth
⎯ a means of identifying the corresponding RF transmitter
⎯ a means of identifying the corresponding lead, if not permanently attached
⎯ any additional information and relevant characteristics, as necessary, to identify the device.
Compliance shall be checked by inspection.
12 Construction of the non-reusable pack
This clause of ISO 14708-1 applies.
8 © ISO 2008 – All rights reserved

13 Markings on the active implantable medical device
This clause of ISO 14708-1 applies except as follows.
13.1
Amendment:
The wet rub test is replaced by subclause 7.1.3 b) of IEC 60601-1:2005, after which the markings shall remain
clearly legible.
14 Protection from unintentional biological effects caused by the active implantable
medical device
This clause of ISO 14708-1 applies except as follows.
14.2
Replacement:
Any part of the implantable neurostimulator, intended in normal use to be in contact with body fluids, shall be
evaluated to determine if the release of particulate matter is hazardous.
⎯ Test: Remove the implantable part aseptically from the non-re-usable pack. Immerse the implantable part
in a bath of approximately 9 g/l saline solution, suitable for injection, or filtered saline or ultra-pure water,
in a neutral glass container. The volume of the saline in millilitres shall be (5 ± 0,5) times the numerical
value of the surface area of the implantable part expressed in cm . The container shall be covered with a
glass lid and maintained at 37 °C ± 2 °C for between 8 h and 18 h, the bath being agitated throughout the
period. A reference sample of similar volume shall be prepared from the same batch of saline, maintained
and agitated in a similar way to the specimen. A sample of liquid from the specimen bath and from the
reference bath shall be compared using apparatus suitable for measurement of particle size, such as
apparatus operating on the light blockage principle [see method 2.9.19 of the European Pharmacopoeia,
[3]
3rd edition, 1977, (Council of Europe) ].
The excess average count of particles from the specimen compared to the reference sample shall not exceed
the amount determined, by the manufacturer, to be hazardous. If the manufacturer does not make this
determination then the excess average count shall not exceed 100 per ml greater than 5,0 µm and shall not
exceed 5 per ml greater than 25 µm.
Compliance shall be confirmed by inspection of a design analysis provided by the manufacturer, supported by
the manufacturer’s calculations and data from test studies as appropriate.
14.3
Addition:
[4]
Biocompatibility may be assessed in accordance with one or more parts of ISO 10993, such as ISO 10993-1 .
15 Protection from harm to the patient or user caused by external physical features
of the active implantable medical device
This clause of ISO 14708-1 applies except as follows.
15.1
Amendment:
Clause 23 of IEC 60601-1:1998 is replaced by subclause 9.3 of IEC 60601-1:2005. (See Clause 5.)
Compliance shall be checked as specified in IEC 60601-1.
16 Protection from harm to the patient caused by electricity
This clause of ISO 14708-1 applies except as follows.
16.1
Amendment:
Clause 19 of IEC 60601-1:1998 is replaced by subclause 8.7 of IEC 60601-1:2005. (See Clause 5.)
16.2
Addition:
If the results of a risk assessment or other means (e.g. published data, test studies, calculations) indicate that
the current limit should be less than 1 µA for a particular application, then the allowable limit shall be changed
so that the risk is mitigated.
NOTE This subclause is intended to include implantable parts that depend on a source of electrical energy, such as
RF receivers.
16.3
Replacement:
Insulating parts of implantable leads or extensions that incorporate electrical conductors shall be designed to
withstand the electrical stresses placed on the insulation in normal working conditions over the planned
lifetime of the product.
Compliance shall be confirmed by inspection of a design analysis provided by the manufacturer, supported by
the manufacturer’s calculations and data from test studies as appropriate.
Additional subclause:
16.101 The design of the neurostimulator shall include protection of the electrical output pulse characteristics
from unintended changes.
NOTE 1 Examples of unintended changes are excess charge density, excess voltage, sudden changes in stimulation
amplitude and rate runaway.
Compliance shall be confirmed by inspection of a design or risk analysis provided by the manufacturer,
supported by the manufacturer’s calculations and data from test studies as appropriate.
NOTE 2 The analysis can be included in results from the risk analysis performed in accordance with 19.3
10 © ISO 2008 – All rights reserved

17 Protection from harm to the patient caused by heat
Replacement:
No outer surface of an implantable part of the implantable neurostimulator shall be greater than 2 °C above
the normal surrounding body temperature, in normal operation or single-fault condition, unless the
manufacturer demonstrates that a higher temperature rise is justified for a particular application.
Compliance shall be confirmed by a review of the manufacturer’s documentation, including results from
modelling, a design or risk assessment, test studies, or other appropriate means.
NOTE At the present time some studies have shown that, depending on the location of specific tissue within the
human body, a 2 °C temperature limit can be unnecessarily restrictive. Under this circumstance, the manufacturer is
allowed the burden of substantiation.
18 Protection from ionizing radiation released or emitted from the active implantable
medical device
This clause of ISO 14708-1 applies.
19 Protection from unintended effects caused by the device
This clause of ISO 14708-1 applies except as follows.
19.2
Replacement:
If the service life (see 3.106) of the implantable neurostimulator is dependent upon an implanted source of
electrical energy, such as a battery, an indication shall be provided that gives an advanced notice of energy
source depletion. The manufacturer shall define the expected duration of the remaining service life following
this notice.
Compliance shall be confirmed by inspection of a design analysis provided by the manufacturer, supported by
the manufacturer’s calculations and data from test studies as appropriate.
NOTE This subclause is also applicable to rechargeable energy sources.
19.3
Replacement:
An implantable neurostimulator shall be designed so that the failure of any single component, part or (if the
device incorporates a programmable electronic system) software program shall not cause an unacceptable
hazard.
⎯ Assessment: Risk assessment and risk control shall be conducted in accordance with published
[5]
standards, such as ISO 14971 .
Compliance shall be confirmed by a review of the risk management report or equivalent manufacturer’s
documents.
19.4
Amendment:
The Assessment is amended to allow clinical investigations conducted in accordance with published
[6] [7]
standards, such as ISO 14155-1 and ISO 14155-2 .
20 Protection of the device from damage caused by external defibrillators
This clause of ISO 14708-1 applies.
21 Protection of the device from changes caused by high-power electrical fields
applied directly to the patient
This clause of ISO 14708-1 applies.
22 Protection of the active implantable medical device from changes caused by
miscellaneous medical treatments
Addition:
Other treatments and procedures, such as (but not limited to) MRI, PET scans, therapeutic ultrasound and
lithotripsy, shall also be considered. Compliance shall be confirmed by a review of the manufacturer’s
documentation, including results from modelling, a design or risk assessment, test studies, or other
appropriate means.
23 Protection of the active implantable medical device from mechanical forces
This clause of ISO 14708-1 applies except as follows.
23.1
Replacement:
Non-implantable parts of neurostimulators shall comply with subclause 15.3 of IEC 60601-1:2005. (See
Clause 5). The number of drops for patient-carried parts that are hand-held shall be three from each of three
different starting orientations encountered during normal use (see subclause 15.3.4.1 of IEC 60601-1:2005).
Compliance shall be checked as specified in IEC 60601-1.
23.2
Amendment:
The implantable parts of the neurostimulator shall be constructed to withstand the mechanical forces that can
occur during normal conditions of use.
a) test frequency range: 5 Hz to 500 Hz;
2 2
b) acceleration spectral density: 0,7 (m/s ) /Hz;
c) shape of acceleration spectral density curve: flat horizontal, 5 Hz to 500 Hz;
d) duration of testing: 30 min in each of three mutually perpendicular axes.
12 © ISO 2008 – All rights reserved

24 Protection of the active implantable medical device from damage caused by
electrostatic discharge
Replacement:
Non-implantable parts of a neurostimulator shall comply with subclause 6.2.2 of IEC 60601-1-2:2007.
(See Clause 5.)
Compliance shall be checked as specified in IEC 60601-1-2.
25 Protection of the active implantable medical device from damage caused by
atmospheric pressure changes
This clause of ISO 14708-1 applies.
26 Protection of the active implantable medical device from damage caused by
temperature changes
This clause of ISO 14708-1 applies except as follows.
26.1
Amendment:
Clause 42 of IEC 60601-1:1998 is replaced by subclause 11.1 of IEC 60601-1:2005. (See clause 5.)
27 Protection of the active implantable medical device from electromagnetic non-
ionizing radiation
Replacement:
27.101 Immunity
Implantable parts of the implantable neurostimulator shall not cause any harm because of susceptibility to
electrical influences due to external electromagnetic fields, whether through malfunction of the device,
damage to the device, heating of the device or by causing local increase of induced electrical current density
within the patient.
Compliance shall be confirmed by review of test results and documentation, prepared by the manufacturer, for
the tests in 27.103 to 27.106.
27.102 General test conditions
a) Operating mode
During immunity testing, each function of the implantable neurostimulator associated with essential
performance shall be tested in a mode that is most critical from a patient outcome perspective, based on a risk
analysis. The test documentation shall state the function and mode used.
NOTE For example, essential performance could very well be related to pulse amplitude or to other output
characteristics where a sudden change could be hazardous.
b) Performance criteria
Under the test conditions specified in Clause 27, each function of the implantable neurostimulator that is
tested [see 27.102 a)] shall be evaluated for general performance using the appropriate criteria stated in
Table 101. If DUT performance satisfies the criteria stated, then compliance with the requirements of the
test(s) is, consequentially, achieved. For criterion B, performance degradation, loss of function or unintentional
responses are allowed if no unacceptable risk is created.
NOTE A risk assessment can demonstrate that a hazard, created as a result of performance degradation, loss of
function, or an unintentional response, does not result in an unacceptable risk.
The following degradations are not allowed:
⎯ component failures;
⎯ changes in programmable parameter settings;
⎯ reset to factory defaults;
⎯ change of operating mode;
⎯ false alarms;
⎯ initiation of any unintended operation.
Table 101 — General performance criteria of the DUT for the immunity tests in clause 27
Criterion During test After test Test summary
A Operate as intended Operate as intended 27.103 – 1 mT level
No loss of function No loss of function 27,104 – A-line
No unintentional responses No degradation of performance 27.105 – 16 V/m
Conforms to device specs 27.106 – 40 mW
B Allowed if no unacceptable risk: Operate as intended 27.103 – 50 mT level
Performance degradation No loss of function 27.104 – B-line
Loss of function No degradation of performance 27.105 – 140 V/m
Unintentional responses Conforms to device specs
Lost functions shall be self-
recoverable
C Manufacturer defined Manufacturer defined 27.106 – optional levels

Test documentation shall include the details of the performance criteria used, a description of the methods
used to verify performance, justification for any allowances of this subclause used, and a report of the test
results indicating DUT performance as it pertains to criterion A, B or C.
Electromagnetic interference that the patient should avoid or be aware of, as a result of DUT performance
during these immunity tests, shall be described in the accompanying documentation (see 28.22).
c) DUT configuration
The DUT shall consist of the IPG, lead and any other implantable part necessary for it to achieve its intended
function. Lead length and layout are described in the test setup for each test.
14 © ISO 2008 – All rights reserved

Neurostimulators that have more than one available electrode configuration for stimulation, such as bipolar or
unipolar, shall be tested with the electrode configuration that is the most susceptible to electromagnetic
interference.
NOTE For magnetic field tests the electrode configuration that is normally the most susceptible is unipolar. For
electric fields, susceptibility is usually dependant upon neurostimulator design implementation.
Test documentation shall describe the DUT configuration and environmental conditions affecting the test
(e.g. temperature and pressure).
d) Testing of normally non-observable functions
If the operation of a function to be tested [see 27.102 a)] cannot normally be observed or verified during the
test, a method shall be provided for determining performance. The use of special hardware or software might
be necessary.
e) Implantable neurostimulators that use wireless telemetry
For a wireless telemetry function tested to satisfy the requirements of 27.102 a), criterion B shall apply in an
exclusion band. All other functions shall comply with the requirements as stated.
The exclusion band shall not be larger than normally required for the telemetry function to operate as intended.
f) Implantable RF receiver type neurostimulator
For a neurostimulator that has a design based on a non-implantable RF transmitter and implantable RF
receiver the appropriate tests in IEC 60601-1-2 shall apply. The test setup for the implantable part shall be
based on the setup described in 27.105.
NOTE The tests in Clause 27 of this part of ISO 14708 do not apply. An implantable RF receiver works in tandem
with a non-implantable transmitter that is subject to IEC 60601-1-2. The RF receiver needs only to be subjected to
radiated immunity in accordance with IEC 60601-1-2.
27.103 Protection from static magnetic fields
The assessment of the implantable neurostimulator for static magnetic fields is made by exposure of the DUT
to two levels of static (non time varying) fields.
⎯ Test: General test conditions are described in 27.102.
Test levels: two test field strengths are used, applying different performance criteria to each. A lower level
of 1 mT shall be subjected to the DUT, applying performance criterion A, as stated in 27.102 b). A second
level of 50 mT shall be used, applying performance criterion B.
Test setup: the apparatus for generating the magnetic field shall be capable of producing a field with
uniformity of dB over an area of radius 7,5 cm (minimum) that lies on a plane parallel to the apparatus.
+ 3
This plane shall be called the central plane. The uniformity of the magnetic field is only prescribed over the
central plane, which contains imaginary Y and Z axes. Uniformity is not prescribed in the X+ or X− direction,
which represents the imaginary, perpendicular, axis running through the centre of the plane of the apparatus
and the central plane.
For most test configurations [see 27.102 c)] a uniform area of radius 7,5 cm will be large enough to cover the
DUT. If not, the uniform area shall be increased until it meets the requirements of this subclause.
Place the DUT at the centre of the central plane where the magnetic field is the most uniform. The plane of the
largest surface area of the DUT is placed parallel to the central plane (this exposes the neurostimulator’s
largest surface to the primary magnetic flux lines which are perpendicular to the central plane). This is the only
orientation of the DUT that is requ
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