ISO 14708-7:2013

Implants for surgery - Active implantable medical devices - Part 7: Particular requirements for cochlear implant systems

ISO 14708-7:2013 specifies requirements that are applicable to those active implantable medical devices that are intended to treat hearing impairment via electrical stimulation of the auditory pathways. The tests that are specified in ISO 14708-7:2013 are type tests and are to be carried out on samples of a device to show compliance. ISO 14708-7:2013 is also applicable to non-implantable parts and accessories of the devices.

Implants chirurgicaux — Dispositifs médicaux implantables actifs — Partie 7: Exigences particulières pour les systèmes d'implant cochléaire

General Information

• Status: Withdrawn
• Publication Date: 07-Jan-2013
• Withdrawal Date: 07-Jan-2013
• ICS: 11.040.40 - Implants for surgery, prosthetics and orthotics
• Technical Committee: ISO/TC 150/SC 6 - Active implants
• Drafting Committee: ISO/TC 150/SC 6/WG 3 - Cochlear implants
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 20-Dec-2019
• Completion Date: 13-Dec-2025

Relations

• Revised: ISO 14708-7:2019 - Implants for surgery - Active implantable medical devices - Part 7: Particular requirements for cochlear and auditory brainstem implant systems
• Effective Date: 25-Oct-2014

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 14708-7
First edition
2013-01-15
Implants for surgery — Active
implantable medical devices —
Part 7:
Particular requirements for cochlear
implant systems
Implants chirurgicaux — Dispositifs médicaux implantables actifs —
Partie 7: Exigences particulières pour les systèmes d’implant cochléaire
Reference number
©
ISO 2013
© ISO 2013
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any
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Published in Switzerland
ii © ISO 2013 – All rights reserved

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and abbreviations . 3
5 General requirements for non-implantable parts . 3
6 Inspection and measurement . 4
6.1 Measurement of output signal characteristics . 4
6.2 Measurement of the output signal amplitude and pulse width . 4
6.3 Impedance measurement accuracy . 4
7 General arrangement of the packaging . 5
8 General markings for active implantable medical devices . 5
9 Markings on the sales packaging. 5
10 Construction of the sales packaging. 6
11 Markings on the sterile pack. 6
12 Construction of the non-reusable pack
......................................................................................................................................... 6
13 Markings on the active implantable medical device . 7
14 Protection from unintentional biological effects being caused by the active implantable
medical device. 7
15 Protection from harm to the patient or user caused by external physical features of the
active implantable medical device . 8
16 Protection from harm to the patient caused by electricity . 8
17 Protection from harm to the patient caused by heat . 8
18 Protection from ionizing radiation released or emitted from the active implantable
medical device. 8
19 Protection from unintended effects caused by the device . 9
20 Protection of the device from damage caused by external defibrillators .9
21 Protection of the device from changes caused by high power electrical fields applied
directly to the patient .10
22 Protection of the active implantable medical device from changes caused by
miscellaneous medical treatments .10
23 Protection of the active implantable medical device from mechanical forces .13
24 Protection of the active implantable medical device from damage caused by
electrostatic discharge .18
25 Protection of the active implantable medical device from damage caused by atmospheric
pressure changes .18
26 Protection of the active implantable medical device from damage caused by
temperature changes .18
27 Protection of the active implantable medical device from electromagnetic non-
ionising radiation .19
28 Accompanying documentation .21
Annex AA (informative) Relationship between the fundamental principles in ISO/TR 14283 and
the clauses of this part of ISO 14708 .24
Annex BB (informative) Relationship between the clauses of this part of ISO 14708 and the
fundamental principles listed in Annex A .37
Annex CC (informative) Notes on EN 45502-2-3 (basis for this part of ISO 14708) .39
Annex DD (informative) Notes on theoretical modelling to demonstrate compliance with
Clause 27 .47
Annex EE (informative) Notes on EMI measurements to demonstrate compliance with Clause 27 49
Bibliography .53
iv © ISO 2013 – 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 14708-7 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
— Part 5: Circulatory support devices
— Part 6: Particular requirements for active implantable medical devices intended to treat tachyarrhythmia
(including implantable defibrillators)
— Part 7: Particular requirements for cochlear implant systems
Introduction
This International Standard specifies particular requirements for active implantable medical devices
used to treat hearing impairment via electrical stimulation (for example cochlear implant systems or
auditory brainstem implant systems), to provide basic assurance of safety for both patients and users.
A cochlear implant system or auditory brainstem implant system is an active implantable
medical device comprising implantable and non-implantable parts (external parts). The power
source may be externally derived or from an internal battery. The implant system is designed to
restore hearing via electrical stimulation of the auditory pathways. Externally or internally processed
acoustic information is converted to electrical stimulation signals which are delivered via one or more
electrodes. The working parameters of the device may be adjusted via a non-implantable accessory.
This International Standard is relevant to all parts of implant systems, including accessories.
The requirements of this International Standard supplement or modify those of 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.
Figures or tables that are additional to those of Part 1 are numbered starting from 101; additional
annexes are lettered AA, BB, etc.
In this part of ISO 14708, terms printed in small capital letters are used as defined in Clause 3. Where
a defined term is used as a qualifier in another term, it is not printed in small capital letters unless the
concept thus qualified is also defined.
vi © ISO 2013 – All rights reserved

INTERNATIONAL STANDARD ISO 14708-7:2013(E)
Implants for surgery — Active implantable medical devices —
Part 7:
Particular requirements for cochlear implant systems
1 Scope
This part of ISO 14708 specifies requirements that are applicable to those active implantable medical
devices that are intended to treat hearing impairment via electrical stimulation of the auditory
pathways. Devices which treat hearing impairment via means other than electrical stimulation are not
covered by this part of ISO 14708.
The tests that are specified in this part of ISO 14708 are type tests and are to be carried out on samples
of a device to show compliance.
This part of ISO 14708 is also applicable to non-implantable parts and accessories of the devices (see
NOTE).
The electrical characteristics of the implantable part are determined by either the appropriate
method detailed in this part of ISO 14708 or by any other method demonstrated to have an accuracy
equal to, or better than, the method specified. In the case of dispute, the method detailed in this part of
ISO 14708 applies.
NOTE A device that is commonly referred to as an active implantable medical device can in fact be a single
device, a combination of devices, or a combination of a device or devices and one or more accessories. Not all
of these parts are required to be either partially or totally implantable, but there is a need to specify some
requirements of non-implantable parts and accessories if they could affect the safety or performance of the
implantable part.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
This clause of ISO 14708-1 applies except as follows:
Additional references:
ISO 10993-1, Biological evaluation of medical devices — Part 1: Evaluation and testing within a risk
management process
ISO 11607-1, Packaging for terminally sterilized medical devices — Part 1: Requirements for materials,
sterile barrier systems and packaging systems
ISO 14155, Clinical investigation of medical devices for human subjects — Good clinical practice
ISO 14971, Medical devices — Application of risk management to medical devices
IEC 60068-2-27, Environmental testing — Part 2-27: Tests — Test Ea and guidance: Shock
IEC 60068-2-31, Environmental testing — Part 2-31: Tests — Test Ec: Rough handling shocks, primarily for
equipment-type specimens
IEC 60068-2-47, Environmental testing — Part 2-47: Test — Mounting of specimens for vibration, impact
and similar dynamic tests
IEC 60068-2-64, Environmental testing — Part 2-64: Tests — Test Fh: Vibration, broadband random and
guidance
IEC 60068-2-75, Environmental testing — Part 2-75: Tests — Test Eh: Hammer tests
IEC 60118-6, Hearing aids — Part 6: Characteristics of electrical input circuits for hearing aids
IEC 60601-1:2006, Medical electrical equipment — Part 1: General requirements for basic safety and
essential performance
IEC 60601-1-2, Medical electrical equipment — Part 1-2: General requirements for basic safety and essential
performance — Collateral standard: Electromagnetic compatibility — Requirements and tests
IEC 61000-4-2, Electromagnetic compatibility (EMC) — Part 4-2: Testing and measurement techniques —
Electrostatic discharge immunity test
IEC 62304, Medical device software — Software life cycle processes
EN 1593, Non-destructive testing — Leak testing — Bubble emission techniques
EN 13185, Non-destructive testing — Leak testing — Tracer gas method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 14708-1 and the following apply.
3.3.1
cochlear implant system
CIS
active implantable medical device, comprising implantable and non-implantable parts, intended to
treat hearing impairment via electrical stimulation of the cochlea
3.3.2
auditory brainstem implant system
BIS
active implantable medical device, comprising implantable and non-implantable parts, intended
to treat hearing impairment via electrical stimulation of the auditory brainstem
3.3.3
implant system
either cochlear implant system or auditory brainstem implant system
3.3.4
non-implantable part
external part of the implant system
Note 1 to entry: Examples would include, but are not limited to, sound processor, microphone, coil or power source.
3.3.5
stimulator
implantable part of the implant system containing electronic circuitry required to produce
electrical stimulation
3.3.6
body-worn
non-implantable part of the implant system and worn on the body (e.g. belt or ear level)
3.5.1
electrode contact
electrically conducting part which is designed to form an interface with body tissue or body fluid
2 © ISO 2013 – All rights reserved

3.5.2
electrode array
distal part of a lead containing more than one electrode contact
3.5.3
reference electrode
electrically conducting part designed as return path for electrical stimulation current
3.5.4
distal
located away from the point of attachment to the stimulator
3.5.5
proximal
located closest to the point of attachment to the stimulator
3.9.1
model designation
name and/or a combination of letters and numbers used by a manufacturer to distinguish, by function
or type, one device from another
3.9.2
serial number
unique combination of letters and/or numbers, selected by the manufacturer, intended to distinguish a
device from other devices with the same model designation
3.20.1
output signal
electrical output, either pulsatile or analogue, of an implant system intended to stimulate the
auditory pathways
3.20.2
pulse
specified electrical output signal (voltage or current) of a specified amplitude and duration
3.20.3
biphasic pulse
pulse which has both negative and positive going phases
3.22.1
use-before-date
date after which the manufacturer recommends that the implant system should not be implanted
3.22.2
magnet
component producing an external magnetic flux
4 Symbols and abbreviations
There are no requirements specified in this part of ISO 14708. However this does not preclude the use of
symbols defined in other standards nor special symbols defined in the accompanying documentation.
5 General requirements for non-implantable parts
5.1 This subclause of ISO 14708-1 applies.
5.2 Replacement
Software of an active implantable medical device or software that falls within the definition of
an active implantable medical device shall be designed according to software life cycle process
activities compliant with IEC 62304 and validated.
6 Inspection and measurement
If this part of ISO 14708 refers to inspection of design analysis documentation provided by the
manufacturer, it shall include an inspection of the risk management file as required by ISO 14971.
6.1 Measurement of output signal characteristics
The measurement shall be performed with the implantable part of the implant system at a temperature
of (37 ± 2) °C. The implant system shall be configured to use its maximum number of outputs and
each output shall be programmed to its maximum value (amplitude and pulse width). An input signal
equivalent to 70dB SPL shall be applied to the microphone. Where applicable, the transcutaneous link
shall operate over a distance of (5 ± 1) mm. Where the implant system provides alternative output
signals each shall be measured and listed separately. To facilitate connection the test sample may be
unfinished. The accuracy of the amplitude measurement shall be better than ± 5 % taking all errors into
consideration.
6.2 Measurement of the output signal amplitude and pulse width
A representative sample of the implant system shall have each output connected to a 1 kΩ (±1 %) load
resistor (see Figure 101) and configured per 6.1. An oscilloscope shall be adjusted to display the full
output at its maximum resolution. The measurement shall be made in the peak of the output signal.
Each output shall be in turn connected to the oscilloscope and the amplitude and pulse width shall be
measured. The median of the amplitudes and pulse widths and their range shall be recorded and the
result shall be expressed in μA and μs.
6.3 Impedance measurement accuracy
Where the implant system allows an impedance measurement (either by telemetry or direct
measurement) the manufacturer shall specify the accuracy of the impedance measurement for a
10 kΩ load resistor. The measurement conditions shall be chosen to reflect normal clinical practice.
The measurement shall be repeated on every output (see Figure 101). The accuracy of the impedance
measurement shall be expressed as a percentage.
Implantable
part
NOTE Ground is connected to the external reference electrode, if available.
Figure 101 — Measurement of output signal amplitude and load impedance
4 © ISO 2013 – All rights reserved

7 General arrangement of the packaging
7.1 This subclause of ISO 14708-1 applies.
7.2 This subclause of ISO 14708-1 applies.
8 General markings for active implantable medical devices
8.1 This subclause of ISO 14708-1 applies.
8.2 This subclause of ISO 14708-1 applies.
9 Markings on the sales packaging
9.1 This subclause of ISO 14708-1 applies.
9.2 This subclause of ISO 14708-1 applies except as follows:
Replacement:
The sales packaging shall bear the name and address of the manufacturer, the address including at least the
city and country. The sales packaging shall bear the name and address of the authorized representative,
if the manufacturer does not have a registered place of business in the European Community.
Compliance is checked by inspection.
9.3 Replacement
Where an IMPLANT SYSTEM is supplied in separate sub-assembly packaging, each individual SALES
PACKAGING shall bear a description of the contents of the packaging, the model designation or part
number and, if applicable the batch number or the serial number.
Compliance is checked by inspection.
9.4 This subclause of ISO 14708-1 applies.
9.5 This subclause of ISO 14708-1 applies.
9.6 This subclause of ISO 14708-1 applies.
9.7 Replacement
The sales packaging of implantable parts of an active implantable medical device shall bear the
use-before-date, as expressed in 9.6.
Compliance shall be checked by inspection.
9.8 This subclause of ISO 14708-1 applies.
9.9 This subclause of ISO 14708-1 applies.
9.10 This subclause of ISO 14708-1 applies.
9.11 This subclause of ISO 14708-1 applies.
9.12 Additional subclause
Where an implant system is supplied in separate sub-assembly packaging, each individual sales packaging
shall bear a description of the contents of the packaging, the model designation or part number and, if
applicable, the batch number or the serial number.
Compliance shall be checked by inspection.
10 Construction of the sales packaging
10.1 This subclause of ISO 14708-1 applies.
10.2 This subclause of ISO 14708-1 applies.
10.3 This subclause of ISO 14708-1 applies.
Additional note:
NOTE Removable stickers, which provide supplementary information exceeding the information specified in
Clause 9 need not to be subjected to the test specified in 10.3.
10.4 This subclause of ISO 14708-1 applies.
11 Markings on the sterile pack
11.1 This subclause of ISO 14708-1 applies.
11.2 This subclause of ISO 14708-1 applies.
11.3 This subclause of ISO 14708-1 applies.
11.4 This subclause of ISO 14708-1 applies.
11.5 This subclause of ISO 14708-1 applies.
11.6 This subclause of ISO 14708-1 applies.
11.7 This subclause of ISO 14708-1 applies.
11.8 This subclause of ISO 14708-1 applies.
11.9 This subclause of ISO 14708-1 applies.
11.10 This subclause of ISO 14708-1 applies.
NOTE This subclause can be fulfilled using an unambiguous symbol.
12 Construction of the non-reusable pack
12.1 This subclause of ISO 14708-1 applies. except as follows:
Replacement:
6 © ISO 2013 – All rights reserved

The non-reusable pack shall comply with ISO 11607-1.
Compliance shall be checked by inspection and by review of records provided by the manufacturer.
12.2 This subclause of ISO 14708-1 applies.
12.3 This subclause of ISO 14708-1 applies.
13 Markings on the active implantable medical device
13.1 This subclause of ISO 14708-1 applies.
13.2 This subclause of ISO 14708-1 applies.
13.3 Replacement
Implantable parts of an implant system shall be unequivocally identifiable (particularly with regard
to the model designation of the device), when necessary, without the need for a surgical intervention.
Compliance shall be confirmed by inspection of the procedure defined by the manufacturer in the
instructions for use (see 28.6).
13.4 This subclause of ISO 14708-1 applies.
14 Protection from unintentional biological effects being caused by the active im-
plantable medical device
14.1 This subclause of ISO 14708-1 applies.
14.2 Replacement
Any implantable part of the active implantable medical device, intended in normal use to be in
contact with body fluids, shall cause no unacceptable release of particulate matter when the device is
used as intended by the manufacturer.
Test:  The implantable part of the implant system shall be removed aseptically from the non-reusable
pack. The implantable part shall be immersed in a bath of saline solution, approximately 9 g/l and
suitable for injection in a neutral glass container. The volume of the saline in millilitres (ml) 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 ± 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 V.5.7.1 of the European Pharmacopoeia) or the electrical zone sensing principle (the Coulter
principle, see Appendix XIII of the British Pharmacopoeia).
Compliance shall be confirmed if the excess average count of unintentional particles from the specimen
compared to the reference sample does not exceed 100 per ml greater than 5,0 µm and does not exceed
5 per ml greater than 25 µm.
14.3 Replacement
This subclause of ISO 14708-1 applies with the addition that ISO 10993-1 shall be used.
14.4 This subclause of ISO 14708-1 applies.
15 Protection from harm to the patient or user caused by external physical fea-
tures of the active implantable medical device
15.1 This subclause of ISO 14708-1 applies.
15.2 Replacement
Implantable parts of an implant system shall have no surface features, such as sharp corners or edges
that could cause excessive reaction or inflammation beyond that caused by the implanting procedure, or
rough surfaces which are not required for the correct functioning of the device.
Compliance shall be confirmed if records provided by the manufacturer establish that the safety of the
physical characteristics has been verified with appropriate methods.
16 Protection from harm to the patient caused by electricity
16.1 Replacement
Electrical audio inputs into non-implantable parts of an implant system shall comply with the
requirements for electrical safety of the hearing aid standard IEC 60118-6. Other electrical inputs or
outputs of non-implantable parts of an implant system that allow the non-implantable part to be
connected to supply mains or mains powered devices which do not meet the insulation requirements
of IEC 60601-1 shall either contain or be provided with a separation device which complies with the
applicable clauses regarding insulation of IEC 60601-1 (separation device as defined in IEC 60601-
1:2006, 16.5.).
NOTE A separation device is not required for battery powered devices when used alone.
Compliance shall be checked as specified in IEC 60601-1 (if applicable) and by review of the documentation
provided by the manufacturer.
16.2 Replacement
Except for its intended function, implantable parts of an implant system shall be electrically neutral
when in contact with the body. No leakage current (direct current) of more than 0,1 µA shall be sustained
in any of the current pathways when the device is in use.
Compliance shall be confirmed by inspection of test procedures and results provided by the manufacturer.
16.3 This subclause of ISO 14708-1 applies.
17 Protection from harm to the patient caused by heat
17.1 This subclause of ISO 14708-1 applies.
17.2 This subclause is to be left vacant for future editions.
18 Protection from ionizing radiation released or emitted from the active im-
plantable medical device
18.1 This subclause of ISO 14708-1 applies.
8 © ISO 2013 – All rights reserved

18.2 This subclause of ISO 14708-1 applies.
18.3 This subclause of ISO 14708-1 applies.
19 Protection from unintended effects caused by the device
NOTE See also 28.20.
19.1 This subclause of ISO 14708-1 applies.
19.2 Replacement
If the implantable part of an implant system contains within it a source of power, such as a battery, the
implant system shall include an ‘indicator’ that gives advance notice of energy source depletion to the
clinician and user.
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.
19.3 This subclause of ISO 14708-1 applies.
19.4 This subclause of ISO 14708-1 applies except as follows:
Replacement of the assessment:
Side effects and benefits from the intended use of the device shall be identified either by reference
to current medical practice and demonstrated by analogy, or by reference to clinical investigations
conducted according to ISO 14155.
Additional subclauses:
19.5 The physical, biological and geometric properties of the implantable parts of an implant system
shall, as far as necessary, be designed to ensure that device removal and replacement with a device from
the same manufacturer is not compromised.
Compliance shall be confirmed by inspection of a design analysis provided by the manufacturer and
where available supported by appropriate test and clinical data e.g. post market surveillance data
relating to device replacement.
19.6 The implantable stimulator case of an implant system intended in normal use to be in contact
with body fluids shall provide sufficient hermeticity so that no fluid can infiltrate the stimulator case.
Tests:  Fine and gross leak tests shall be conducted on the hermetic casing of the stimulator of an
implant system in accordance with EN 13185 and EN 1593. If a group A technique is used from the
EN 13185 standard then a gross leak test is not required; if a group B technique is used then the gross
leak test shall follow the fine leak test.
NOTE The manufacturer should include adequate hermeticity testing in their manufacturing process.
Compliance shall be confirmed by inspection of test procedures and results provided by the manufacturer
−9 3
and by the device leak rate not exceeding 5 × 10 Pa m /s for the fine leak test and no definite stream
of bubbles, or two or more large bubbles, originating from the same point of the stimulator case for
the gross leak test.
20 Protection of the device from damage caused by external defibrillators
NOTE See also 28.12.
20.1 This subclause of ISO 14708-1 is not applicable to this part of ISO 14708.
20.2 This subclause of ISO 14708-1 applies.
21 Protection of the device from changes caused by high power electrical fields
applied directly to the patient
NOTE See also 28.12 and 28.13.
21.1 Replacement:
The implantable part of an implant system shall be designed so that stray, high frequency current from
surgical equipment (surgical diathermy) flowing through the patient shall not permanently affect the
device provided the implant System does not lie directly in the path between cutting and return (RF
earth) electrodes (see also requirement for warning advice, 28.13).
Test:  Use a signal generator with an output impedance of 50 Ω (R1). The test signal frequency shall be
500 kHz sinusoid and the open loop test signal amplitude 20 V .
pp
The implant System shall be switched off. Each output of the implantable part of the implant system
shall be connected via a resistor (R) of 4,7 kΩ to a common point which shall be connected to the output of
the signal generator (see Figure 102). The reference electrode of the implantable part of the implant
System shall be connected via a 100 Ω resistor (R3) to the ground of the signal generator.
R2 = 4,7 kΩ
Rn = 4,7 kΩ
R1 = 50 kΩ
Cochlear or
Brainstem
Implant
500 kHz
V
T
20 V
pp
R3 = 100 kΩ
Figure 102 — Test set-up for proof of protection from high frequency currents caused by
surgical equipment
Apply the test signal in 10 bursts each for a duration of 1 s, allowing a recovery period of 5 s between bursts.
Compliance shall be confirmed if, after completing the test procedure and reactivating, the implant
System characteristics conform with the manufacturer’s original specification.
21.2 This subclause is to be left vacant for future editions.
22 Protection of the active implantable medical device from changes caused by
miscellaneous medical treatments
NOTE See also 28.12, 28.14 and 28.15.
10 © ISO 2013 – All rights reserved

22.2 Clause 22 of ISO 14708-1 applies.
Additional subclauses
22.2 Implantable parts of an implant system shall be identified where MRI safety is declared by the
manufacturer (see 28.8). The manufacturer shall declare (see 28.12) the conditions (including the specific
field strengths) under which the safety of MRI testing has been verified. The declaration shall include the
risk for demagnetisation, image distortion and instructions for safe performance of MRI investigations,
where applicable.
The risks to a subject implanted with an implant system entering an MRI machine may be grouped
under the following areas: force from the magnetic field, heat generation, unintentional device output
and implant damage. Each of these factors shall be tested as follows:
a) Force
The implantable part of an implant system shall not produce harm to the patient through
mechanical forces which might occur during MRI scanning.
Test:  The force is calculated from the magnetic field strength of the MRI machine, the magnetic
properties of any ferromagnetic or paramagnetic materials incorporated in the implantable part,
the strength of any internal magnet and the geometry of the implanted part containing the magnet.
Alternatively, the force may be measured.
Compliance shall be confirmed if the maximum force under worst case orientation is below 10 N or
no displacement of the implant or magnet is demonstrated.
b) Heat generation
The implantable part of an implant system shall not generate excessive heat during MRI scanning.
Test:  Two identical covered plastic containers shall be selected with volume sufficient to contain the
entire implantable part of the implant system ensuring that it will be completely submerged. The
volume of the saline shall be 3 ± 0,3 × the volume of the implantable part. The volume of the implant
plus saline in one container shall be identical to the volume of the saline in the other container. The
implantable part of the implant system stored at the temperature of the scanning location of the
MRI department for the past 24 h shall be placed in one container. Both containers shall be filled
with 9 g/l saline also previously stored for the previous 24 h in the same location. The temperature
of each container’s saline shall be recorded using a digital thermometer with a resolution of 0,1 °C.
Room temperature is also recorded. Both containers are then placed in a position within the MRI
machine judged to receive the highest amount of RF power. An MRI test sequence representing the
worst case clinical scan typically performed (highest absorption rate) shall be initiated and run for
at least 15 min. Immediately after the scan is completed the two containers shall be removed from
the MRI chamber and the temperature of each container recorded again. Alternatively ASTM F2182
may be used to test for the temperature rise at the implant and lead.
Compliance shall be confirmed if the temperature difference between the two containers or
temperature rise at the implant or electrode tip is less than 2 °C.
c) Unintentional output
The implantable part of an implant system shall not generate harmful output to the patient during
MRI scanning.
Test:  The implantable part of the implant system shall be placed inside the MRI machine. Two
modified implant systems shall be tested: One implant system which has an additional sense
resistor R1 placed in series with the reference electrode, with access to both ends of R1, and a
second implant system with access to the supply voltage of the implant. A receive/transmit optical
fibre circuit and oscilloscope shall be connected to the sense resistor R1 as shown in Figure 103.
For this test it is essential to use shielded twisted pair cable and a passive low pass filter. The
recommended resistors are R1 = 10 kΩ, R2 = R3 = 22 kΩ. The three resistors shall be mounted within
an area of less than 1 cm . A low pass filter is formed by the resistors R2 to R5 and the capacitor
C1. The input impedance of the optical fibre unit should be taken into account when specifying the
values R4 and R5. The cut-off frequency shall be approximately 10 kHz. All components should be
constructed using surface mount technology and made of non-magnetic materials. The oscilloscope
shall be placed outside the MRI room or a measurement equipment which is not affected by the MRI
machine shall be used. The implantable part of the implant system including the electrode array
and the reference electrode shall be placed in a container filled with 9 g/l saline or a gelled
phantom material of similar conductivity in a position typical for an implanted device. An MRI test
sequence representing the worst case clinical scan shall be performed. The output charge shall be
determined from the voltage measured across the sense resistor.
Compliance shall be confirmed if the charge per phase does not exceed 10 nC.
R4
Shielded twisted
C1
pair wires
(as short as possible)
R5
Electrode array(s)
Optical
ibre
transmitter
R3
R2
R1
Optical
ibre to
remote
measurement
Cochlear or
equipment
Brainstem
Implant
Reference electrode
Saline
Figure 103 — Test set-up for proof of protection from harmful output during MRI scanning
d) Implant damage
The implantable part of an implant system shall not be damaged during MRI scanning.
Test:  The following test shall be applied for each field strength specified as MRI safe by the implant
manufacturer. A representative sample of the implantable part of the implant system shall be
completely immersed in a non-metallic container filled with 9 g/l saline. The container shall be
placed in the centre of the MRI machine and a worst case scan as described in b) initiated.
Compliance shall be confirmed if after the scan the device conforms to the manufacturer’s
specifications. A reduction in strength of the internal magnet is acceptable providing the
manufacturer makes available an alternative fixation method and appropriate information in the
labelling (see 28.12).
12 © ISO 2013 – All rights reserved

22.3 The implantable part of an implant system shall withstand levels of therapeutic ionising radiation
as specified by the implant manufacturer.
Test:  Three samples of the implantable part of the implant system shall be irradiated using Photon
radiation with 5 Gray doses to a maximum cumulative dose as specified by the manufacturer. Irradiation
shall be delivered at 24 h intervals, at least four times per week. After each exposure the device shall be
powered using normal clinical conditions. Before each irradiation the amplitude of the output signal
shall be monitored as specified in 6.1 and 6.2. While the output signal amplitude of each sample
remains within 10 % of its value before the first irradiation, a further dose is applied. The manufacturer
shall state the median dose of the three samples for which the output signal last met the above criteria.
The labelling statement (see 28.12) shall include a safety margin of 20 % of this dose.
Compliance shall be checked by review of the test results and documentation provided by the
manufacturer.
23 Protection of the active implantable medical device from mechanical forces
23.1 Replacement:
Non-implantable parts of an implant system that are either hand-held in normal use, portable or
body worn and weigh not more than 10 kg, shall be constructed so that shocks caused by mishandling
or dropping while in use do not damage the device.
Test:  Hand-held, body-worn or portable parts of an implant system weighing up to 10 kg shall
withstand the free fall test in accordance with IEC 60068-2-31, under the following conditions:
a) test surface: hard wood, density not less than 630 kg/m , thickness between 50 mm and 55 mm;
b) height of fall:
hand-held devices: 1 m;
portable devices: 50 mm;
body worn part: 1,5 m or the height of normal use whatever is more severe;
c) attitude from which specimen is dropped: attitude as in normal use.
Compliance shall be confirmed if the dropped part operates as stated in the manufacturer’s original
specification.
23.2 Replacement:
The implantable part of the implant system shall be constructed to withstand the mechanical forces
that might occur during normal conditions of use, including the time prior to implantation.
Test:  The implantable part of the implant system, mounted in accordance with the requirements
and guidance given in IEC 60068-2-47, shall withstand a random vibration test in accordance with
IEC 60068-2-64, Test Fh, under the following conditions:
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.
Compliance shall be confirmed if, after completing the test procedur
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