Electromagnetic comppyatibility - sensibility of ......Electromagnetic Interference...

Sveučilište u ZagrebuFakultet elektrotehnike i računarstva

Biomedicinska instrumentacija

Electromagnetic compatibility -g p ysensibility of implantable

l t i d i t diff telectronic devices to differentkinds of electroterapykinds of electroterapy

Ratko Magjarević University of Zagreb

Faculty of Electrical Engineering and ComputingCroatia

[email protected]

Electromagnetic compatibility (EMC)Electromagnetic compatibility (EMC)

• the degree to which an electronic system is able to function compatibly with other p yelectronic systems

• not susceptible to interference• not susceptible to interference• not produce interference

Opposite Electromagnetic interference• Opposite: Electromagnetic interference (EMI)

EMC - Implantable Devices 2

Electromagnetic interference (EMI)Electromagnetic interference (EMI)

di t b th t ff t l t i l i it d• disturbance that affects an electrical circuit due to

l t ti di ti– electromagnetic radiation – electromagnetic conduction (bellow ~50 MHz)

electrostatic discharge– electrostatic discharge• emitted from a source

external– external– internal

• may interrupt degrade or obstruct the• may interrupt, degrade or obstruct the performance of an electronic circuit



I d ti li• Inductive coupling– Inductive coupling occurs where the source and

receiver are separated by a short distance (typicallyreceiver are separated by a short distance (typically less than a wavelength). Strictly, "Inductive coupling" can be of two kinds, electrical induction and magnetic induction. It is common to refer to electrical inductioninduction. It is common to refer to electrical induction as capacitive coupling, and to magnetic induction as inductive coupling.

• Capacitive coupling• Capacitive coupling– Capacitive coupling occurs when a varying electrical

field exists between two adjacent conductors typically j yp yless than a wavelength apart, inducing a change in voltage across the gap.



C d ti liConductive coupling– Conductive coupling occurs when the coupling path

between the source and the receptor is formed bybetween the source and the receptor is formed by direct contact with a conducting body, for example a transmission line, wire, cable, PCB trace or metal enclosure.enclosure.

• Conduction modes– Conducted noise is also characterised by the way it y y

appears on different conductors:• Common-mode or common-impedance[1]) coupling: noise

appears in phase (in the same direction) on two conductors . pp p ( )• Differential-mode coupling: noise appears out of phase (in

opposite directions) on two conductors.



M ti li• Magnetic coupling– Inductive coupling or magnetic coupling (MC) occurs

when a varying magnetic field exists between twowhen a varying magnetic field exists between two parallel conductors typically less than a wavelength apart, inducing a change in voltage along the receiving conductor.receiving conductor.

• Radiative coupling– Radiative coupling or electromagnetic coupling occurs p g g p g

when source and victim are separated by a large distance, typically more than a wavelength. Source and victim act as radio antennas: the source emits or radiates an electromagnetic wave which propagates across the open space in between and is picked up or received by the victim.


received by the victim.

EMI GrowthEMI Growth

The power density of EMI in an average urban environment since 1945 Light pollution is 1 to 1 correlated with 1945. g p

electromagnetic energy leaking into the environment. Where there is artificial light there is electromagnetic interferences.

EMC - Implantable Devices 7from: www.biotele.com/EMI.htm

g

Pacemakers and EMIPacemakers and EMI

pacemaker – life saving device++

EMI - may interrupt, degrade or obstruct the f f l t i i itperformance of an electronic circuit

=EMI may be life-threatening for patients with

pacemakerspacemakersRuggera P.S. and R. Elder, Electromagnetic Radiation Interference with Cardiac


Pacemakers, DHEW publication BRH DEP 71-5, 1971

EMI to (other) Medical DevicesEMI to (other) Medical DevicesDocumented cases:Documented cases:• a ventilator suddenly

changes its breathchanges its breath rate

• an electric poweredan electric powered wheelchair suddenly veers off course

• an apnea monitor fails to alarm......

Casamento JP, Ruggera PS.Applying standardized electromagnetic compatibility testing methods for evaluating radiofrequency interference with ventilators Biomed Instrum Technol


evaluating radiofrequency interference with ventilators, Biomed Instrum Technol. Witters D.M. and P. S. Ruggera, EMC of Powered Wheelchairs and Scooters, Proc. RESNA '94

Solving EMI at System LevelSolving EMI at System LevelEMI i l• EMI involves: – the device itself – the environment in which it is used– the environment in which it is used– anything that may come into that environment

• EMI - a systems problem requiring a systems approach

• EMI solution requires involvement of – the (medical) device industry, – the EM source industry (power industry,

telecommunications industry....), – the clinical user and patient


the clinical user and patient

IEC ClassificationIEC ClassificationI t ti l• International Electrotechnical Commission (IEC) classification of EMclassification of EM environment

• Conditions for the location d f l l EMand power of local EM

energy sources (e.g., transmitters)T bl 1 i di t th• Table 1 indicates the general classifications and the upper range of radiated EM field strength specifiedEM field strength specified for each environment.


Sources of EMI• Radio broadcasting

• Television

• Public safety (police fire highway forestry and emergency services)Public safety (police, fire, highway, forestry, and emergency services)

• Land transportation (taxis, trucks, buses, railroads)

A t di• Amateur radio

• Cellular phones and paging systems

• Industrial, scientific, and medical

• Citizens' band (CB) radio

• Radar .....


Factors affecting EMCFrequency, Wavelength, and Antenna Effect

g

Depth of Implantation

Modulation

E l f R d d D i M lf ti D t EMIExamples of Recorded Device Malfunction Due to EMI

Electroencephalographic interferenceec oe cep a og ap c e e e ce Impedance-based apnea monitor mishaps

Monitor alarmsMechanism of death due to apneapSusceptibility to EMI

Drug-infusion pump mishaps Ventilator mishaps

EMC - Implantable Devices 13 Powered-vehicle mishaps

Examples of Recorded Device Malfunction Due to EMIExamples of Recorded Device Malfunction Due to EMI

Cellular and Mobile Telephone-Generated EMI

I f t di t i h Infant radiant warmer mishaps

Miscellaneous medical device mishaps

Health effects

Blood pressure monitor Blood pressure monitor


C di P k d EMI

Implanted pacemakers Pacemaker malfunction due to cellular

Cardiac Pacemakers and EMI

Implanted pacemakers Communication with an implanted

pacemaker Failure modes

Pacemaker malfunction due to cellular phones Pacemaker malfunction due to magnetic

resonance imagers Failure modes Effect of EMI on pacemaker function Pacemaker malfunction due to

electrosurgery

resonance imagers Pacemaker malfunction due to

microwave-oven EMI Pacemaker malfunction due to low-electrosurgery

Abandoned pacemaker lead accident

Pacemaker malfunction due to

Pacemaker malfunction due to lowfrequency EMI

Electronic surveillance systems Pacemaker malfunction due to

paging system


Implanted cardioverter defibrillator (ICD)

• Effect of EMI on ICDs

• ICD malfunction due to arc welders

• Cell-phone EMI

• Slot machine EMI

• Pacemaker and ICD interaction• Pacemaker and ICD interaction

• Improper electrode placement

• Powerline ICD accident


Electrostatic Discharge

Introduction Introduction

ESD testing

Mechanism of action of ESD

ESD incidents

Effect of ESD on human subjects


Model of InterferenceModel of Interference

EMC - Implantable Devices 1818from: S. Hrabar, Analysis of EMI between mobile telephone and impllanted medical device, Ph.D. thesis, 1999

Definitions to EMC problemsDefinitions to EMC problemsI it t di t b bilit f d i t• Imunity to disturbance – ability of a device to perform without degradation in presence of EMIC tibilit l l ifi d EM di t b• Compatibility level – specified EM disturbance level expected to be impressed to a deviceI it l l l l f i EM• Imunity level – max level of given EM disturbance incident on a particular deviceI it i diff b t th i it• Imunity margin – difference between the imunity level and EM compatibility level

from IEEE standards


Immunity LimitImmunity Limit

EMC - Implantable Devices 2020from: S. Hrabar, Analysis of EMI between mobile telephone and impllanted medical device, Ph.D. thesis, 1999

Block diagram of an unipolar pacemaker


Unipolar SensingUnipolar SensingUnipolar SensingUnipolar SensingProduces a large potential difference due to:

A cathode and anode that are farther apart than in a bipolar systemy

What about EMI?

_


Block diagram of a bipolar pacemaker


Bipolar SensingBipolar SensingProduces a smaller potential differenceProduces a smaller potential difference due to the short interelectrode distance:

•Electrical signals from outside the gheart such as myopotentials are less likely to be sensed


Amplifier Circuits DC coupledAmplifier Circuits - DC coupled


Amplifier Circuits AC coupledAmplifier Circuits - AC coupled


Biopotential Isolation AmplifierBiopotential Isolation Amplifier


Electromagnetic InterferenceElectromagnetic Interference


Electromagnetic Interference (EMI)Electromagnetic Interference (EMI)Electromagnetic Interference (EMI)Electromagnetic Interference (EMI)

Interference is caused by electromagnetic energy with a source that is outside the body

Electromagnetic fields that may affect pacemakers are radio-frequency waves

•50-60 Hz are most frequently associated with k i t fpacemaker interference

Few sources of EMI are found in the home or office but several exist in hospitalsoffice but several exist in hospitals


EMI May Result in the Following Problems:EMI May Result in the Following Problems:

•OversensingOversensing

•Transient mode change (noise reversion)

•Reprogramming (Power on Reset or “POR”)


Oversensing May Occur When EMI Signals Are Oversensing May Occur When EMI Signals Are Incorrectly Interpreted as P Waves or R WavesIncorrectly Interpreted as P Waves or R Waves

•Pacing rates will vary as a result of EMI:

– Rates will accelerate if sensed as P waves in dual-chamber systems (P waves are “tracked”)

R t ill b l i hibit d if d i i l h b– Rates will be low or inhibited if sensed in single-chamber systems, or on ventricular lead in dual-chamber systems


EMIEMIEMIEMI

“N i ” d b th“Noise” sensed by the pacemaker

Should have paced


N i R iN i R iNoise ReversionNoise Reversion

Continuous refractory sensing will cause pacing at the lower or sensor driven rate

Lower Rate Interval

Noise Sensed

SRSR SR SRVPVP

SRSR SR SR


EMI May Lead to Inadvertent Reprogramming of EMI May Lead to Inadvertent Reprogramming of the Pacing Parametersthe Pacing Parametersgg

D i ill t t P R t (POR “b k ” d )Device will revert to Power on Reset (POR or “backup” mode)Power on Reset may exhibit a mode and rate change which are often the same as ERIIn some cases reprogrammed parameters may beIn some cases, reprogrammed parameters may be permanent


New technologies will continue to createNew technologies will continue to createNew technologies will continue to create New technologies will continue to create new, unanticipated sources of EMI:new, unanticipated sources of EMI:

• Cellular phones (digital)


Sources of EMI Are Found Most Sources of EMI Are Found Most C l i H it l E i tC l i H it l E i tCommonly in Hospital EnvironmentsCommonly in Hospital Environments

Sources of EMI that interfere with pacemaker operation p pinclude surgical/therapeutic equipment such as:

•Electrocauteryy•Transthoracic defibrillation•Extracorporeal shock-wave lithotripsy•Therapeutic radiation•RF ablation•TENS units•MRI


Sources of EMI Are Found More Rarely in:Sources of EMI Are Found More Rarely in:

•Home, office, and shopping environments

•Industrial environments with very high electrical outputs

T t ti t ith hi h l t i l ith•Transportation systems with high electrical energy exposure or with high-powered radar and radio transmission

Engines or subway braking systemsAirport radarAirport radarAirplane engines

•TV and radio transmission sites•TV and radio transmission sites


Electrocautery is the Most Common Hospital Source of Electrocautery is the Most Common Hospital Source of Pacemaker EMIPacemaker EMI

O tO t P tiP ti•• OutcomesOutcomes– Oversensing–inhibition– Undersensing (noise

•• PrecautionsPrecautions– Reprogram mode to

VOO/DOO, g (reversion)

– Power on Reset– Permanent loss of

– or place a magnet over device

– Strategically place the Permanent loss of pacemaker

– output (if battery voltage is low)

g y pgrounding plate

– Limit electrocautery bursts to 1-second low)

– burst every 10 seconds– Use bipolar electrocautery

forcepsforceps


Transthoracic DefibrillationTransthoracic DefibrillationTransthoracic DefibrillationTransthoracic Defibrillation

• OutcomeInappropriate

• PrecautionsPosition defibrillation– Inappropriate

reprogramming of the pulse generator (POR)D t k

– Position defibrillation paddles apex-posterior (AP) and as far from the pacemaker and leads as– Damage to pacemaker

circuitrypacemaker and leads as possible


Magnetic Resonance Imaging (MRI) is Generally Magnetic Resonance Imaging (MRI) is Generally Contraindicated in Patients with PacemakersContraindicated in Patients with Pacemakers

• Outcomes • Precautions– Extremely high pacing rate– Reversion to asynchronous

pacing

– Program pacemaker output low enough to create persistentpacing pnon-capture, ODO or OVO mode


Lithotripsy Shock Waves May Have an Effect on Lithotripsy Shock Waves May Have an Effect on Pacemaker SystemsPacemaker SystemsPacemaker SystemsPacemaker Systems

O t i P ti• Outcomes indual-chamber modes:– Inhibition of ventricular

• Precautions:– Program pacemaker to VVI

or VOO modepacing

• Outcomes in rate adaptive pacemakers

– Lithotriptor focal point should be greater than 6 inches from the pacemaker

– High pacing rates– Piezoelectric crystal

damage

– Carefully monitor heart function throughout procedureg


Radiation Energy May Cause Permanent Damage Radiation Energy May Cause Permanent Damage

•Certain kinds of radiation energy may cause damage to the semi-conductor circuitry

– Ionizing radiation used for breast or lung cancer therapy

•Damage can be permanent and requires replacement of the•Damage can be permanent and requires replacement of the pacemaker


Therapeutic Radiation May Therapeutic Radiation May Cause Severe DamageCause Severe Damage

• Outcomes:– Pacemaker circuit damage

• Precautions:– Keep cumulative radiation g

– Loss of output– “Runaway”

pabsorbed by the pacemaker to less than 500 rads; shielding may be required

– Check pacemaker after radiation sessions for changes in pacemaker function (can be done transtelephonically)


Pacemaker Features That Address Pacemaker Features That Address InterferenceInterferenceInterference Interference

Pacemaker sensing circuits amplify, filter and either process or reject incoming signals

InputInputBandpass

filterAbsolute

valueReversion

circuitLevel

detectorPacemaker

logic

Sensitivity adjustment


Equipment interference with pacemakers

At homeAt homeHousehold devices: shavers, hairdryers and microwave ovens, household tools such as drills,mowers and electric screwdrivers - not be a problem, as long as they are well maintained.

PhonesUseing a mobile phone or a cordless phone is safe, but it is best to keep the phone more than 15 centimetres (6 inches) from your pacemaker. Always

th th it id t k d d t t thuse the ear on the opposite side to your pacemaker, and do not put the phone in a pocket over your pacemaker.

Travelling and security systemsAi i d i h f i h d lib iAirport screening systems and anti-theft systems in shops and libraries may, very rarely, cause problems with pacemakers. There is also a small chance that you may trigger the alarms. Always carry your pacemaker registration card with you. In some countries you may be asked to go g y y y gthrough the security system. Move quickly through the gateway.


Equipment interference with pacemakers

At workAt work Some workplaces have strong electromagnetic fields which can interfere with your pacemaker. Arc-welding is an example.

In hospitals Some hospital equipment may interfere with pacemakers. Some types of equipment used in surgery can also cause problems. M ti i i (MRI) b d fMagnetic resonance imaging (MRI) scans can be dangerous for pacemaker patients..


The SureScan™Pacing SystemThe SureScan Pacing SystemThe first pacing systems The first pacing systems p g yp g ydesigneddesigned, tested and , tested and approved for MRIapproved for MRI


The SureScan™Pacing SystemThe SureScan Pacing System“Patients and physicians need a device p y

specifically designed to address the unique hazards of magnetic resonance imaging.”

– Professor Richard Sutton St Mary’s Hospital LondonSt. Mary s Hospital, London


Pacing Systems need to be MRI safe by Design not ChanceMRI-safe by Design – not Chance

• Control about Reed switch behavior• Better protection against electromagnetic• Better protection against electromagnetic

interference leading to electrical resetP bl MRI d f diff• Programmable MRI modes for different pts. populations

• Leads with less RF-induction and less temperature increasep


SureScan Innovations

Change: Lead input filtering capacitancef /

Change: Reed switch replaced by Hall sensor Benefit: Control switch behavior

Benefit: Minimize the energy induced on leads/discharged at tip

Benefit: Control switch behavior

Change: Internal power supply circuit protectionBenefit: Prevents the energy induced on the telemetry antenna from

disrupting the internal power supplies

R d S i h

disrupting the internal power suppliesChange: Significantly reduced ferromagnetic components

Benefit: Decrease susceptibility to magnetic attraction


Hall sensor

Reed Switch


Change: Dedicated SureScan modes: asynchronous pacing or non‐pacing mode(Programmer+ Device Software/Firmware)

Benefit: Ease of patient managementSuspension of diagnostic data collection and atrial arrhythmia therapy



Change: 5086 lead geometry and i l k (fil # i hinternal make‐up (filar #, pitch, size, Impedance, …) changed to prevent interactions with gradient field and produce low RFfield and produce low RF conduction characteristicsBenefit: Reduces lead heating Standard MRI

Pitch



Change: Radiographic markersBenefit: Ease of device identification


The SureScan™Pacing SystemMRI f b D i t ChMRI-safe by Design – not Chance

1997

Initiate Research

2001Begin technology

work with international

e perts

2004Commence formaldiscussions withregulatory bodies(TUV FDA )

2005Complete first

systemmodifications:

start extensive

2006Finalize devicemodifications;define human

clinical trial

2007Commenceworldwide

EnRhythm MRI™Pacing System

2008Clinical trialcompleted;

CE mark received; EnRhythm MRI

2010

2nd generationSureScan Pacing

Systems market releaseexperts (TUV, FDA, …) test program clinical trial g y

clinical trialy

market releasemarket release

MRI Unsafe MRI Conditional: Safe for use inSafe for use in MRI under certain conditions


Approval by the authoritiespp o a by t e aut o t es

SureScan was rigorously tested clinicallySureScan was rigorously tested, clinically studied, and CE-mark approvedThe CE marking (also known as CE mark) is a mandatory conformance mark on many products placed on the single market in the European Economic Area (EEA) The CE marking certifies that a product has metEconomic Area (EEA). The CE marking certifies that a product has met EU consumer safety, health or environmental requirements.


Literature• Yadin, D et al, eds. “Clinical Engineering” CRC Press, 2003• Kimmel D.D., D.D. Gerke, Protecting Medical Devices FromKimmel D.D., D.D. Gerke, Protecting Medical Devices From

Electromagnetic Interference, Designer's Handbook: Medical Electronics,

• Brown,B.H. et alt., “Medical Physics and Biomedical Engineering”., y g gIoP Publishing, London, reprinted 2001.

• Webster,J.G. (Ed.), “Medical Instrumentation, Application and Design.” 2nd ed., J. Wiley & Sons, Inc., New York, 1995.

• Webster,J.G. (Ed.), “Bioinstrumentation”. John Wiley & Sons, Inc., New York, 2003

In Croatian:Š Š• Šantić, A., “Biomedicinska elektronika”, Školska knjiga, Zagreb, 1995


Standards RegulationsStandards, Regulations....• EU directive 2004/108/CE (previously 89/336/EEC) on EMC• CISPR 11 - Industrial, scientific and medical (ISM) radio-frequency

equipment - Electromagnetic disturbance characteristics - Limits and methods of measurement

• ANSI/AAMI PC69:2000, “Active implantable medical devices-Electromagnetic compatibility- EMC test protocols for implantable cardiac pacemakers and implantable cardioverter defibrillators”, American National S 2000Standards Institute, 2000.

• Medical Electrical Equipment, Part 1: General Requirements for Safety, Collateral Standard: Electromagnetic Compatibility, International El t t h i l C i i IEC 60601 1 2Electrotechnical Commission IEC 60601-1-2

• IEC 1000-4-3 Electromagnetic Compatibility (EMC)- Part 4; Testing and measurement techniques- Section 3: Radiated, Radio frequency, electromagnetic field immunity testelectromagnetic field immunity test

• The Safe Medical Devices Act (SMDA) of 1990, Public Law 91- 4243. • International Electrotechnical Committee IEC/TC or SC: TC77,

Electromagnetic Compatibility Between Electrical Equipment Including


Electromagnetic Compatibility Between Electrical Equipment Including Networks, Classification of Electromagnetic Environments ..........

Electromagnetic comppyatibility - sensibility of ......Electromagnetic Interference...

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