Eucomed Position Paper on Ultra Low Power Active Implants and ...

<strong>Eucomed</strong> <strong>Position</strong> <strong>Paper</strong> on
Ultra Low Power Active Implants and Accessory Equipment (ULP-AMI)
Introduction
<strong>Eucomed</strong> is an organization of medical and prosthesis manufacturers with a European presence
that was organized in its present form in November 1999. The organization represents the
interests of the majority of the non-pharmaceutical European medical technology industry – a key
sector that provides in excess of 100 000 products to hundreds of millions of people in Europe
and beyond. <strong>Eucomed</strong> represents more than 3000 individual business entities active in the
medical technology industry. Small and medium size companies make up circa 94% of this
sector. <strong>Eucomed</strong> Membership comprises some 25 national and pan-European Associations and
some 43 multinational-medical-technology manufacturers with a major European presence.
A significant segment of these manufacturers produce products related to ultra low power active
medical implants and their accessory equipment (such as programmers, patient devices) which
provide life saving therapies. These devices employ inductively coupled telemetry systems as
well as heart pacing functions, defibrillation, drug delivery and direct nerve stimulation, among
others, to millions of patients in the European region and worldwide.
Discussion
Current medical-implant-systems providing life saving and enhancing therapies must employ
these telemetry technologies in order to adjust the operating parameters of the implant as the
needs of the patient change. This same telemetry capability also permits patient information, e.g.
electrocardiograms stored within the implant, to be downloaded to an external system thus
providing the physician with valuable information concerning the patient’s condition.
The implant telemetry systems of the ULP-AMI manufacturers, as described above, typically
consist of an external device referred to as a programmer/controller that exchanges data with the
implant typically operating at frequencies of the range of 9 kHz-315 kHz using inductive magnetic
fields technology. Patient protection, mandated under the AIMD, requires prevention of corruption
of the data by ambient signals. To provide this protection medical implant systems employ
several interference mitigation techniques that ensure data integrity. The techniques are
described in Annex 1.
Conclusions
Since 1992 the ULP-AMI devices have been through the Conformity Assessment procedures of the
Active Implantable Medical Device Directive (AIMD) 90/385/EEC and are approved to bear the
CE-Marking by the relevant Notified Body in the EU.
Medical telemetry systems, for implants or other devices, have been used worldwide for many
years, performing valuable services related to reducing medical costs and providing improved
patient care. These systems, that are carefully scrutinized by competent medical authorities and
Ultra Low Power Active Implants and Accessory Equipment (ULP-AMI)
R&TTE TG Board Approved on issue date May 7 2001
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are subject to applicable standards imposed by the medical authorities that mandate patient
safety, must be protected above all else. This is also emphasized in the R&TTE directive: “without
prejudice to the application of Directives 93/42/EEC and 90/385/EEC to medical devices and
active implantable medical devices, respectively.”
One example of such a standard in Europe, is EN 60601-1-4 Medical Electrical equipment, Part 1.
General requirements for safety, Section 1.4 Collateral standard: General requirements for
programmable electrical medical systems. This specifically states in sub-clause 52.204.3.1.6 that
data protection from human intentional or unintentional causes must be satisfactorily addressed
in the hazard analysis in the governing standard. The hazard analysis is reviewed by the
governing medical authorities for acceptability in showing that the data is protected from
corruption. Other standards are also used to meet these requirements. The medical community
itself can attest to the adequacy of the above techniques in ensuring system design prevents
ambient signals from interfering with these telemetry systems.
The magnetic field strengths from the ULP-AMI are well below the levels specified in EN 300 330
as well as the limits of applicable EMC Standards.
The zone of influence and periodicity of signals transmitted from these systems is very small due
to their very low power, low duty cycle, frequency of operation, and the rapid attenuation rate as
a function of distance. Because of these factors, these systems pose no threat of harmful
interference to existing users of the spectrum
Reiterating, the above processes and technical design characteristics ensure that these medical
systems will not cause harmful interference to the existing broadcasters, that the primary status
broadcasters will not cause interference to the medical systems and that the patient’s safety is
always assured.
Proposal
With the above in mind, it is the considered opinion of <strong>Eucomed</strong> to seek an appropriate solution
by extending ANNEX 12 of CEPT/ERC/Rec 70-03 with the following frequency bands for use
specifically by active medical implants and programmer/controllers in the range of 9 kHz up to
315 kHz:
a) 9 kHz – 135 kHz
b) 135 kHz – 148,5 kHz
c) 148,5 kHz – 255 kHz
d) 255 kHz – 283,5 kHz
e) 283,5 kHz - 315 kHz
Therefore <strong>Eucomed</strong> is kindly asking the Short Range Device Management Group to consider:
1) Adopting, under Annex 12 of CEPT/ERC/Rec 70-03, the above stated frequency bands
specifically for low frequency, low power, inductively coupled active medical implant telemetry
systems that have been used for many years by this branch of the medical manufacturing
industry.
2) Concurrently with this request, we urge the appropriate authorities to consider including this
band in the framework of a Decisions Status if at all possible.
3) There should be no licensing requirements for the use of these ULP-AMI devices and their
accessory equipment.
Ultra Low Power Active Implants and Accessory Equipment (ULP-AMI)
R&TTE TG Board Approved on issue date May 7 2001
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Annex to <strong>Eucomed</strong> <strong>Position</strong> <strong>Paper</strong> on Ultra Low Power Active Implantable Medical Devices
and Accessory Equipment (ULP-AMI)
Patient protection, mandated under the AIMD, requires prevention of data corruption by ambient
signals. To provide this protection, medical implant systems employ several techniques that protect
the integrity of transmitted data. These techniques are described below:
PROGRAMMER/CONTROLLER
Programmer/Controllers utilize a number of methods for reducing the levels of interference. Some
examples of such methods are:
1. The programmer/controller head is fully enclosed in a conductive shield that provides excellent
isolation to electric fields.
2. The programmer/controller head often incorporates a dual opposing coil design that cancels
out interference sources that are more than a few feet away. In addition, the programming
information transmitted to the implant is encoded with effective error code protection.
3. Further, the valid command set utilized by the programmer is very limited. Thus, even if the
implant did receive and decode a packet containing an error, the demodulated command
would not match a valid command that the implant is capable of recognizing.
IMPLANT
1. Implants require an external stimulus from a specific programmer with a unique signal code to
activate their data exchange (telemetry) circuits. This stimulus can include a strong external
permanent magnet that closes an internal magnetic switch contained in the implant. Once the
implant is activated the programmer/controller will validate the device identification information
and open a programming session. During this programming session all data packets
generated by the implant or the programmer/controller are effectively encoded to make certain
the decoded data is error free. Thus, a corrupted command that passes the CRC check will
not be recognized by the implant.
2. Implants are fully enclosed in a non-ferrous metallic shield exclusive of the leads associated
with implant function. These leads enter through individual chambers within the implant case
and use low-pass filters which will effectively control the coupling of any signal into the implant
sufficiently that no threat to the normal performance of the implant exists.
Ultra Low Power Active Implants and Accessory Equipment (ULP-AMI)
R&TTE TG Board Approved on issue date May 7 2001
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