Electromagnetic Interference With Implantable
Cardioverter-Defibrillators at Power Frequency
An In Vivo Study
Andreas Napp, MD*; Stephan Joosten, MSc*; Dominik Stunder, MSc*;
Christian Knackstedt, MD; Matthias Zink, MD; Barbara Bellmann, MD; Nikolaus Marx, MD;
Patrick Schauerte, MD; Jiri Silny, PhD
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Background—The number of implantable cardioverter-defibrillators (ICDs) for the prevention of sudden cardiac death is
continuing to increase. Given the technological complexity of ICDs, it is of critical importance to identify and control
possible harmful electromagnetic interferences between various sources of electromagnetic fields and ICDs in daily life
and occupational environments.
Methods and Results—Interference thresholds of 110 ICD patients (1-, 2-, and 3-chamber ICDs) were evaluated in a
specifically developed test site. Patients were exposed to single and combined electric and magnetic 50-Hz fields with
strengths of up to 30 kV·m−1 and 2.55 mT. Tests were conducted considering worst-case conditions, including maximum
sensitivity of the device or full inspiration. With devices being programmed to nominal sensitivity, ICDs remained
unaffected in 91 patients (83%). Five of 110 devices (5%) showed transient loss of accurate right ventricular sensing,
whereas 14 of 31 (45%) of the 2- and 3-chamber devices displayed impaired right atrial sensing. No interference was
detected in 71 patients (65%) within the tested limits with programming to maximum sensitivity, whereas 20 of 110
subjects (18%) exhibited right ventricular disturbances and 19 of 31 (61%) subjects exhibited right atrial disturbances.
Conclusions—Extremely low-frequency daily-life electromagnetic fields do not disturb sensing capabilities of ICDs.
However, strong 50-Hz electromagnetic fields, present in certain occupational environments, may cause inappropriate
sensing, potentially leading to false detection of atrial/ventricular arrhythmic events. When the right atrial/right ventricular
interferences are compared, the atrial lead is more susceptible to electromagnetic fields.
Clinical Trial Registration—URL: http://clinicaltrials.gov/ct2/show/NCT01626261. Unique identifier: NCT01626261. (Circulation. 2014;129:441-450.)
Key Words: defibrillators, implantable ◼ electromagnetic fields ◼ power sources ◼ threshold limit values
E
xogenous electric and magnetic fields (EMFs) from sources
such as high-voltage power lines, substations, electronic
article surveillance systems, or electrical appliances induce
noise signals in the human body. They superimpose intrinsic
heart signals and may lead to electromagnetic interference
(EMI) with active implantable medical devices such as cardiac
pacemakers or implantable cardioverter-defibrillators (ICDs).
extremely low-frequency EMFs may disturb cardiac pacemakers or ICDs.
New indications for ICD therapy, especially the implantation
for primary prevention of sudden cardiac death, have substantially increased the number of patients carrying an ICD, thus
emphasizing the need for further investigation and regulation.
In Germany alone, there were 21 609 ICD implantations in
2006, increasing to 42 261 in 2012.2,3 Many of these devices
were implanted in relatively young patients possibly still working with the risk of strong field exposure in specific occupational environments (eg, technician in a power plant). In 2011,
51.1% of all patients with first ICD implantation were <70
years of age and 25.5% were <60 years of age in Germany.4
Clinical Perspective on p 450
First reports of EMI with cardiac implants were published
in the early 1960s.1 During the last decades, many different
studies dealing with EMI have been published; however, to
date there is no conclusive evidence as to which sources of
Received April 7, 2013; accepted October 10, 2013.
From the Department of Internal Medicine I (Cardiology, Pneumology, Angiology) (A.N., C.K., M.Z., B.B., N.M., P.S.) and Research Center for
Bioelectromagnetic Interaction at the Institute of Occupational Medicine; former at the Institute of Hygiene and Environmental Medicine (S.J., D.S.,
J.S.), University Hospital RWTH Aachen, Aachen, Germany; and Department of Cardiology, Maastricht University Medical Center, Maastricht, The
Netherlands (C.K.).
*Drs Napp, Joosten, and Stunder contributed equally.
The online-only Data Supplement is available with this article at http://circ.ahajournals.org/lookup/suppl/doi:10.1161/CIRCULATIONAHA.
113.003081-/DC1.
Correspondence to Andreas Napp, MD, Department of Internal Medicine I (Cardiology, Pneumology, Angiology), RWTH Aachen University,
Pauwelsstrasse 30, 52074 Aachen, Germany. E-mail [email protected]
© 2013 American Heart Association, Inc.
Circulation is available at http://circ.ahajournals.org
DOI: 10.1161/CIRCULATIONAHA.113.003081
441
442 Circulation January 28, 2014
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Additionally, the number and types of EMF sources have likewise risen in daily life and occupational environments over the
past 2 decades. EMI with ICDs may cause inadequate oversensing with subsequent inappropriate shock delivery, inhibition
of pacing, or switch to an asynchronous noise mode. Of note,
inappropriate shock delivery seems to carry an increased risk
for overall survival5 and cause psychological distress.
Safety guidelines of the European Union,6–8 the American
National Standards Institute (ANSI),9 and the International
Commission on Non-Ionizing Radiation Protection10 for the
protection of humans exposed to EMFs do not include patients
with medical devices such as ICDs (Table 1). Nevertheless,
several product standards for manufacturers provide test methodologies (so-called benchmark tests) to evaluate the electromagnetic compatibility performance of ICDs.11–14 However,
these standards achieve electromagnetic compatibility only to
a certain degree. It is important to understand that EMI may
occur despite conformance of cardiac implants to the specific
product standards and the conformance of sources of EMFs to
the human exposure safety guidelines according to the ANSI/
Association for the Advancement of Medical Instrumentation
standard PC69.14 There is a lack of comprehensive data, especially on in vivo exposure, to close the current gap in knowledge about the extent to which patients with cardiac implants
may be influenced by extremely low-frequency EMFs.
The objective of the present study was to provide sound data
on the exposure of ICD patients to extremely low-frequency
EMFs to overcome the existing uncertainty among patients
and physicians. In a clinical in vivo provocation study, ICD
patients were exposed to single and combined 50-Hz EMFs of
up to 30 kV·m−1 (electric field strength) and 2.55 mT (magnetic
flux density). These are the maximum occupational limits in
Germany covering EMFs in the vicinity of high-voltage power
lines, power installations, or other power-operated machines.15
We systematically determined the interference thresholds of
patients’ ICDs, that is, the first occurrence of a sensing failure
under worst-case conditions (eg, maximum sensitivity).
Table 1. Overview of Different Guidelines for the Protection
of Humans Exposed to Electric and Magnetic Fields in the
General Public and Occupational/Controlled Environments at
50 Hz (These Guidelines Do Not Consider Protection of Patients
With Medical Devices)
Environment
EU*
ICNIRP†
ANSI/IEEE‡
General public
Electric field, kV/m
5
5
5
Magnetic field, mT
0.1
0.2
0.904
Occupational
Electric field, kV/m
Magnetic field, mT
10
0.5
10
1
20
2.71
*European Union (EU) guidelines 1999/519/EC from 1999 and 2004/40/EC
from 20046,7; new occupational guidelines are currently being discussed in the
EU parliament.8
†International Commission on Non-Ionizing Radiation Protection (ICNIRP)
guideline from 2010.10
‡American National Standards Institute (ANSI)/Institute of Electrical and
Electronics Engineers (IEEE) guideline C95.6 from 2002; limit values also apply
to 60 Hz.9
Methods
The study design was approved by the institutional review committee for Human Research of University Hospital RWTH Aachen
(www.clinicaltrials.gov; identifier NCT01626261). It consisted of 2
parts: (1) benchmark tests, that is, computer-based tests with ICDs to
develop and validate the method of the provocation study, and (2) a
provocation study, that is, a clinical in vivo study with ICD patients to
determine the individual interference thresholds.
Benchmark Tests
The purpose of the benchmark tests was to determine whether
the interference threshold is independent of the duration of exposure to validate the method of short-term exposure in the in vivo
provocation study. A computer-generated intracardiac electrogram,
corresponding to the European product standard EN 45502-2-2,11
superimposed with a 50-Hz sinusoidal noise signal was fed into
the pace/sense channel of the ICD to be tested. The injected 50-Hz
sinusoidal noise signal simulated the EMF exposure used in the
provocation study. Interference thresholds of different ICDs were
determined and compared under short-term exposure (1.5 seconds,
≈2 consecutive heartbeats) and long-term exposure (30 seconds).
The ICD parameters were set to nominal settings but maximum
sensitivity. The reaction of the ICD was monitored by standard
programming devices. The amplitude of the 50-Hz sinusoidal noise
signal was increased successively until the first sensing failure of
the device occurred (ie, the interference threshold) or the maximum
amplitude (20 mV peak to peak) was reached. A total of 15 different
ICD models were tested (Table 2). ICDs were previously explanted
in patients as a result of battery depletion, device infection, or
upgrade to a different system.
Provocation Study
In the provocation study, ICD patients were systematically exposed
to EMFs of different intensities to define thresholds of EMI at 50 Hz.
For safety reasons, sequences of field exposure in patients were limited to a maximum of 2 consecutive heartbeats (short-term exposure),
and ICD therapies for ventricular tachycardia (VT) and ventricular
fibrillation (VF) were switched off during the investigation.
Patient Population
During the period of September 2009 to December 2012, all
patients presenting to the outpatient pacemaker/ICD clinic of our
department were screened for the study. Of 1983 patients consecutively requested for routine ambulatory ICD follow-up, 386 patients
met the inclusion/exclusion criteria, and 110 gave written informed
consent. Inclusion criteria were age between 18 and 75 years and
device implantation >4 weeks previously. Exclusion criteria were
pacemaker dependency, hyperthyroidism, ineffective oral anticoagulant therapy in case of atrial fibrillation, serum electrolyte disorders, clinically manifest infection, myocardial infarction <30 days,
and pregnancy.
Pretest examination included a 12-lead ECG, device interrogation, and analysis of blood samples (electrolyte levels and
coagulation). Body measurements (height, weight, thorax circumference, shoulder width) and information about the implanted system (manufacturer and model of the device and leads, chest X-ray)
were documented.
Follow-up examination, immediately after the test and again after
4 weeks, included a 12-lead ECG and device interrogation. No device
defects or software resets were seen. Pacing thresholds remained
unchanged at the follow-up visits.
All 110 patients who consented to participate in the study were
included to obtain a comprehensive picture of interference thresholds of
ICDs. Single-chamber ICDs were implanted in 79 patients, dual-chamber ICDs in 16 patients, and 3-lead ICD systems (cardiac resynchronization therapy–defibrillator [CRT-D]) in 15 subjects. One patient (P090)
with a dual-chamber ICD was programmed to the VVI mode because of
an atrial lead defect. This patient was included as single-chamber ICD.
Table 3 shows the characteristics of the 110 patients.
Napp et al ICDs in Power Frequency Electromagnetic Fields 443
Table 2. Interference Thresholds of 15 Different ICDs Determined in Benchmark Tests for 1.5and 30-Second Exposures
Pacing Mode
At 1.5 seconds,
mV
At 30 seconds,
mV
Bio/Lexos VR-T
VVI
1.1
1.2
VOS
Bio/Lexos DR
DDD
0.3
0.4
AOS
Bio/Lumax 300 DR-T
DDD
0.3
0.3
AMS
Bio/Lumax 300 HF-T
CRT-D
0.3
0.3
AOS
Bio/Lumax 340 VR-T
VVI
1.3
1.3
VOS
Bio/Lumos VR-T
VVI
1.1
1.1
VOS
Gui/Ventak Prizm 2 VR
VVI
2
2
VOS
Gui/Vitality 2 T165 DR
DDD
0.3
0.35
AOS
Med/GEM III VR 7231
VVI
0.55
0.55
VOS
Med/InSync III Marquis 7279
CRT-D
0.15
0.15
AMS
Med/InSync Maximo 7304
CRT-D
0.14
0.14
AOS
Med/Marquis 7230Cx
VVI
0.2
0.2
VOS
Med/Marquis DR
DDD
0.1
0.1
AOS
SJM/Atlas II VR V-168
VVI
1
1.1
ND
SJM/Atlas+ VR V-193
VVI
1.1
1.1
AMS
Manufacturer/Model
Dysfunction
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AMS indicates automatic mode switch; AOS, atrial oversense; Bio, Biotronik; Gui, Guidant; ICD, implantable cardioverterdefibrillator; Med, Medtronic; ND, noise detection; SJM, St. Jude Medical; and VOS, ventricular oversense.
Test System
A computer-controlled test system was developed to continuously
monitor EMF generation and to record the patient’s surface ECG signals in real time. Standard programming devices were used to register intracardiac electrograms and marker channels during the entire
examination. The system aligned the phasing between the magnetic
and electric fields so that in combined field settings a maximum disturbance at the input of the ICD was always ensured. Figure 1 shows
a scheme of the technical test setup.
Electric Field Generation
Generation of strong homogeneous electric 50-Hz fields requires special constructions to comply with safety regulations and to ensure
homogeneous fields.16 The geometric constraints of the laboratory
did not allow this. However, the induced current distribution in the
thorax by exogenous electric fields can be reproduced by direct current injection. See the Methods section and Figure I in the onlineonly Data Supplement for validation. The body current that would
be induced by a vertically oriented exogenous electric field is given
according to the Deno formula.17 The system injected this defined
body current between the neck and feet of the patient. This procedure
Table 3. Patient Characteristics
Male/female, n (%)
91/19 (82.7/17.3)
Age, y
57.0±11.3 (22-75)
Height, cm
176.1±8.5 (153-196)
Weight, kg
85.1±15.0 (50-121)
Body mass index, kg/m2
27.4±4.7 (18-47)
ICD manufacturer, n (%)
Biotronik
26 (23.6)
Guidant/Boston Scientific
14 (12.7)
Medtronic
36 (32.7)
St. Jude Medical
34 (30.9)
Data are expressed as mean±SD (range) when appropriate. ICD indicates
implantable cardioverter-defibrillator;
has been described in detail elsewhere.18 The test setup can produce
body currents up to an equivalent exogenous field strength of 30
kV·m−1 (ie, the occupational limit in Germany).15
Magnetic Field Generation
Homogeneous magnetic 50-Hz fields were generated by a vertical
Helmholtz coil setup with a diameter of 180 cm and a distance of
90 cm. The Helmholtz pair of coils was loaded by a power amplifier (Vortex 6, Camco) and a signal generator (33220A, Agilent
Technologies). In this way, homogeneous 50-Hz magnetic fields of
up to 2.55 mT flux density (ie, the occupational limit in Germany)15
can be produced.
Test Procedure
Field exposure was applied for 2 consecutive heartbeats. Each
sequence of exposure was triggered to the R wave of the surface ECG
to start exposure during the blanking time of the device, thus preventing interferences caused by field initiation.
The objective was to determine the lowest interference thresholds
for ICD patients, that is, the first occurrence of a sensing failure, in
either single or combined EMFs. To identify reliable lowest thresholds, worst-case conditions were required and defined as follows:
1.Thorax perpendicular to the orientation of the homogeneous
magnetic field. According to the Faradays law, the induced
noise signal voltage is proportional to the induction area. The
induction area becomes maximum when magnetic fields act
perpendicularly to the frontal plane of the thorax.19
2.Full inspiration. Exposure of electric fields by full inspiration
results in an increase in the noise signal voltage in the body
and hence a potential decline in the interference threshold. It is
supposed that the large volume of insulating air causes a higher
local current density in the area between lung and chest skin.18
3. Sustained pacing, that is, a pacing rate set to a higher value than
the intrinsic heart rate and, for a 2- or 3-chamber device, a foreshortened AV delay. The adjustment of the sensitivity can only
partly be programmed. ICDs automatically adjust their atrial and
ventricular sensitivity thresholds after sensed and paced events,
and only a few parameters, for example, the sensitivity value, can
be set. Depending on the intracardiac electrogram P/R potential,
444 Circulation January 28, 2014
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Figure 1. Scheme of the technical test setup. The patient sat in the center of 2 coils (Helmholtz pair) in an upright position. For current
injection, 4 electrodes were placed on the shoulder/neck of the patient, and 2 electrodes were placed on each leg. The system
continuously monitored and recorded the patient’s surface ECG. Via a programming unit, the intracardiac electrograms were monitored
and printed continuously during electromagnetic field exposure. ICD indicates implantable cardioverter-defibrillator.
device settings, and manufacturer, the sensitivity may be higher
after pacing than after sensing, as explained in device manuals.
4.Maximum sensitivity. ICDs were programmed to the highest
obtainable sensitivity because the interference threshold is
coupled with sensitivity settings.20 Sensitivity has the greatest
impact on interference thresholds of cardiac implants.21
The examination was conducted at maximum and nominal sensitivity, applying worst-case conditions stepwise.
First Run: Maximum Sensitivity
ICDs were set to maximum sensitivity, and interference thresholds were
determined for single and combined EMFs. Then, a second worst-case
parameter was added: The pacing rate was adjusted to ensure continuous
atrial/ventricular pacing, and the previously determined thresholds were
reassessed. Finally, the influence of respiration on the thresholds was analyzed by repeating the exposures while the patient was at full inspiration.
Second Run: Nominal Sensitivity
ICDs were set to nominal sensitivity but maintaining the other worstcase conditions. Nominal sensitivity means that the preset sensitivity
is programmed by the treating physician. Thus, nominal sensitivity
and maximum sensitivity can be equal (eg, in patients with preexisting low R potential). Interference thresholds were determined for
single and combined EMFs at nominal sensitivity. After programming of AV sequential/right ventricular pacing and investigation of
the influence of full inspiration, thresholds were again determined.
At each run and condition, field strengths were increased stepwise
until the individual thresholds were found or maximum field values
(30 kV·m−1/2.55 mT) were reached. For validation, the exposure of
the determined threshold was repeated twice. The strategy of increasing the field strength was based on a binary decision tree, permitting
precise determination within a maximum of 6 steps.
Statistical Analysis
Statistical analysis was performed with MATLAB (MathWorks). Unless
otherwise specified, data are expressed as mean and standard deviation.
Results
Benchmark Tests
The interference thresholds of 15 different ICD models were
determined, which were also part of the provocation study.
The first sensing failure occurred at noise signal amplitudes
between 0.14 and 1.2 mV. Dual-chamber or CRT-D systems
showed lower interference thresholds than single-chamber
ICDs because of the higher sensitivity of the atrium channel.
The interference thresholds of the 1.5-second exposure were
almost identical to the thresholds of the 30-second exposure
(Table 2). The slight differences can be explained by the standard measurement uncertainty. The reaction/dysfunction of
ICDs at the first sensing failure (ie, the interference threshold)
remained the same, independently of the duration of exposure
(either short-term or long-term exposure). Thus, these results
indicate that the interference thresholds obtained in the in vivo
provocation study are also valid for permanent field exposure,
assuming that the other conditions remain constant. In conclusion, the in vivo provocation study allows a general risk
assessment of susceptibility to EMI even if the patients were
only exposed short term (2 consecutive heartbeats).
Of note, the interference thresholds determined in the
benchmark tests cannot be linked directly to the interference
thresholds obtained from the provocation study because of the
missing patient- and lead-related effects.
Provocation Study
Examples of provoked EMI are shown in Figures 2 and 3 and
for atrial and ventricular interference, respectively.
At maximum sensitivity, no interference during EMF
exposure occurred in 71 of 110 implanted devices (64.5%).
The noise signal provoked inadequate ICD responses in 19
patients in the atrial channel and in 20 individuals in the ventricular channel (Figure 4).
Programmed at nominal sensitivity, no disturbance occurred
in 91 of 110 devices (82.7%). In 14 of these 19 ICDs with EMF
interference, the atrial channel was affected, whereas in 5 patients,
interference occurred in the ventricular channel (Figure 4).
At interference thresholds, oversensing in both the atrial and
ventricular channels was the type of the first sensing failure.
None of the tested devices primarily switched into noise mode
Napp et al ICDs in Power Frequency Electromagnetic Fields 445
Figure 2. Biotronik Lumax 540 DR-T
(P085) programmed to maximum
sensitivity (atrium, 0.2 mV; ventricle, 0.5
mV). Electric and magnetic field (EMF)
exposure (30 kV*m-1/1.8 mT) led to
an inappropriate atrial oversense that
caused an inappropriate ventricular pace
and an inadequate mode switch (device
pacing rate, 45 bpm; atrioventricular
delay, 150 milliseconds after sense). The
premature ventricular contractions (PVCs)
evolved spontaneously. Additionally,
inappropriate ventricular oversense
occurred as a result of an automatically
modified sensitivity threshold after
ventricular pace.
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when the first oversensing occurred. One CRT-D showed inhibition of left ventricular pacing (P077).
The percentage of disturbed ICDs per year of market
release showed no dependency on susceptibility to 50-Hz
EMFs (data not shown). Hence, newer ICD models seem not
to be less susceptible, although the number of implants per
year of release was not sufficient for a statistical validation.
The lowest atrial interference thresholds were 15 kV·m−1
in single electric fields (atrial sensitivity, 0.18 mV), 0.45 mT
in single magnetic fields (atrial sensitivity, 0.2 mV), and 3.5
kV·m−1/0.3 mT in combined EMFs (atrial sensitivity, 0.4
mV). Details are given in Table I in the online-only Data
Supplement.
Right Atrial Disturbances
Ventricular interferences were detected in 17 of 110 ICDs
(15.5%) at maximum sensitivity in combined fields of up to 30
kV·m−1 and 2.55 mT. The disturbed ICDs were 16 single-chamber ICDs and 1 CRT-D. An example is depicted in Figure 3.
During single-field application, only 10 ICDs (9.1%) were
disturbed in magnetic fields (8 single-chamber; 2 CRT-Ds) and
none in electric fields. One CRT-D (P077) showed an interference in the left ventricular channel. It was the only left ventricular disturbance elicited in the study; however, it should be noted
that only Biotronik and Guidant/Boston Scientific CRT-Ds provide left ventricular intracardiac electrograms.
At nominal sensitivity, ventricular oversensing of combined
fields was observed in 5 of 110 ICDs (4.5%; 4 single-chamber;
1 dual-chamber). Single magnetic field exposure interfered
with 1 ICD (0.9%). Single electric field exposure did not interfere with ICDs at nominal sensitivity.
Atrial interferences were detected in 19 of 31 (10 dual-chambers; 9 CRT-Ds) 2- or 3-chamber ICDs (61.3%) at maximum
sensitivity in combined fields of up to 30 kV·m−1 (electric field
strength) and 2.55 mT (magnetic flux density). Figure 2 shows
an example of EMI.
In single electric or magnetic field applications, 13 devices
showed interference: 6 (19.4%) in the electric field (3 dual
chambers; 3 CRT-Ds) and 7 (22.6%) in the magnetic field (5
dual-chambers; 2 CRT-Ds).
At nominal sensitivity, 14 of 31 ICDs (45.2%; 9 dual-chambers; 5 CRT-Ds) showed an atrial disturbance in combined
fields of up to 30 kV·m−1 and 2.55 mT.
In single-field applications, only 3 ICDs (9.7%; 2 dualchambers; 1 CRT-D) could be disturbed in magnetic fields and
1 ICD (3.2%) in electric fields.
Right Ventricular Disturbances
Figure 3. Vitality 2 VR T175 (P063) programmed
at ventricular pacing (VVI) at a pacing rate of 75
bpm at maximum sensitivity (0.18 mV). Electric and
magnetic field (EMF) exposure (25.5 kV*m-1/2.15
mT) led to a ventricular oversense in the ventricular
fibrillation (VF) zone that led to pacing inhibition and
maybe to inappropriate antitachycardia therapy (eg,
shock delivery) if it would sustain. EGM indicates
electrogram.
446 Circulation January 28, 2014
Figure 4. Right atrial (RA) and right
ventricular (RV) disturbances caused
by single and combined electric
and magnetic fields (EMFs). CRT-D
indicates cardiac resynchronization
therapy–defibrillator; and ICD, implantable
cardioverter-defibrillator.
Downloaded from http://circ.ahajournals.org/ by guest on June 15, 2017
The lowest ventricular interference thresholds were >2.55
mT in single electric fields, 0.6 mT in single magnetic fields
(ventricular sensitivity, 0.18 mV), and 16.4 kV·m−1/1.8 mT in
combined EMFs (ventricular sensitivity, 0.18 mV). Details are
given in Table II in the online-only Data Supplement.
Interference Thresholds in Relation to Limit Values
The interference thresholds of the disturbed ICDs at maximum and nominal sensitivity within the range of the limit
values set by the European Union and the ANSI/Institute
of Electrical and Electronics Engineers (IEEE; Table 1) are
shown in Figure 5.
At maximum sensitivity, 39 ICDs could be disturbed
in single and combined fields up to the tested limits (30
kV·m−1/2.55 mT). Of these, no interference occurred within
the limit values set by the European Union for the general
public, and only 1 device could be disturbed within the set
occupational limits.
With respect to the limits defined by the ANSI/IEEE C95.6
guideline, the interference thresholds of 3 ICDs with atrial
interference and 1 ICD with ventricular interference were
in the range for the general public. Within the occupational
limits of this guideline, the ICDs of 21 patients could be disturbed: 10 atrial and 11 ventricular disturbances respectively.
Focusing on nominal sensitivity, 19 ICDs could be disturbed
within tested limits; of these, 3 ICDs with atrial interference
were within the limits of the ANSI/IEEE C95.6 guideline for
general public, and 6 ICDs were within the limits for occupational exposure (4 atrial and 2 ventricular disturbances). At
nominal sensitivity, no interference could be elicited within
the European Union limit values in either the general public
or the occupational limits.
Discussion
The main findings of the present study are (see also Table 4)
as follows:
1.Interference of EMFs with ICDs occurred in 17.3% at programmed nominal sensitivity and in 35.5% at maximum sensitivity within the tested limits.
2. Interference of EMFs with the ventricular channel occurred in
4.5% of ICDs at nominal sensitivity and in 15.5% at maximum
sensitivity.
3. EMF interference with the atrial channel occurred in 45.2% at
nominal sensitivity and in 61.3% at maximum sensitivity.
4. No interference occurred within the European Union limit values set for the general public, and only 1 device could be disturbed in the atrial channel within the occupational limits.
5.Within the limit values of the United States (ANSI/IEEE),
EMI with the atrial and the ventricular channel occurred in
4% (general public limits) and 19% (occupational limits) of all
patients.
6.Active pacing of the ventricle increased the susceptibility to
EMI by 91% of all tested ICDs.
The EMF-Portal (www.emf-portal.org), the most comprehensive scientific literature database on the effects of EMFs,
currently reveals ≈300 publications on EMI with cardiac
implants. Although 189 studies have investigated EMI in
the low-frequency range (including direct current), only
47 publications have dealt with the power frequency range
(50/60 Hz). However, many of these 47 publications were
conducted on various numerical and physical models (eg,
see References 22–26). Additionally, there have been a
number of case studies (eg, References 27 and 28) or retrospective observational studies (eg, References 29 and 30).
Another group of publications comprises investigations on
EMI caused by medical electrical equipment working in the
50/60-Hz range.31–33 Even though the first evidence of EMI
appeared in the early 1960s,1 to date, there have been only
4 clinical studies21,34–36 with patients bearing a cardiac
implant under standardized or controlled exposure conditions in the 50/60-Hz power frequency range. Nevertheless,
provocation studies were recommended in numerous previous studies.24,33,35,37 Trigano and coworkers34 showed in a
large in vivo study of cardiac pacemaker patients that single
magnetic fields pulsed at power frequency are able to cause
an inappropriate mode switch and pacing inhibition in unipolar lead configuration. Bipolar sensing seemed to be rather
safe in magnetic fields with a flux density of up to 100 µT.
Recently, Tiikkaja and coworkers36 investigated interference
thresholds of cardiac pacemakers and ICDs at extremely
low-frequency EMFs, but only in a small number of volunteers (13 ICD patients, 11 cardiac pacemaker patients)
at magnetic flux densities not higher than 300 µT and not
considering combined magnetic and electric exposure. None
of the previous studies considered worst-case conditions, for
example, maximum sensitivity of devices or full inspiration
(see Test Procedure).
The present study investigated EMI with ICDs in a large in
vivo study under worst-case conditions. We determined the
Napp et al ICDs in Power Frequency Electromagnetic Fields 447
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Figure 5. Determined interference thresholds of the implantable cardioverter-defibrillators are shown in relation to the limit values of
European Union (EU) and American Nationals Standards Institute/Institute of Electrical and Electronics Engineers (ANSI/IEEE). The
markers represent the interference thresholds of the 39 devices (maximum sensitivity, top) and the 19 devices (nominal sensitivity,
bottom) that could be disturbed within the tested limits.
lowest interference thresholds of 110 ICD patients in single
and combined 50-Hz EMFs of up to 30 kV·m−1 and 2.55 mT.
The determined thresholds also apply for 60 Hz, the
power frequency in the Americas. Previous studies showed
that the susceptibility to EMI of cardiac implants is in the
same range at 50/60 Hz.20,38 The limit values of the American
National Standards Institute do not differ between 50 and
60 Hz (Table 1).
448 Circulation January 28, 2014
Table 4. Number of Right Atrial and Right Ventricular
Disturbances at Maximum and Nominal Sensitivity
Maximum Sensitivity
Nominal Sensitivity
Single E Single B Combined Single E Single B Combined
Field
Field
E/B Field
Field
Field
E/B Field
Right atrial
disturbances,
n (%)
6 (19)
Right
ventricular
disturbances,
n (%)
0 (0)
7 (23)
10 (9)
19 (61)
1 (3)
3 (10)
14 (45)
17 (15)
0 (0)
1 (1)
5 (5)
E indicates electric; and B, magnetic.
Downloaded from http://circ.ahajournals.org/ by guest on June 15, 2017
The knowledge of these interference thresholds closes the
gap in the current guidelines for limiting exposure of ICD
wearers to EMFs. Our data provides evidence that ICD disturbances do not occur within the limits values of the European
Union for the general public (5 kV·m−1/0.1 mT). The first
sensing failures were detected at stronger fields, and only
1 device could be disturbed in the atrial channel within the
range of current European Union limit values for occupational
exposure (10 kV·m−1/0.5 mT). However, new occupational
guidelines are currently being discussed in the European
Union parliament (up to 10 kV·m−1/6 mT at 50 Hz).8 Our data
indicate that, should these limits come into action, ICD disturbances are more likely to occur.
Right Atrial Disturbances
In 19 of 31 patients (61.3%), an atrial oversensing was registered in EMFs within the tested limits (30 kV·m−1/2.55 mT).
The higher probability of EMF interference in the atrial channel can be ascribed to the small intrinsic atrial signals with
consecutively higher programmed atrial sensitivities and a
corresponding poor signal-to-noise ratio in the atrium channel.
Right atrial disturbances may lead to a scenario that potentially
carries risks for patients; sustained oversensing can cause an
inadequate mode switch to VVI(-R)/DDI(-R). If patients are in
sinus rhythm, the asynchronous pacing mode may increase the
risk for developing atrial fibrillation or pacemaker syndrome.
The latter is caused by an atrioventricular dyssynchrony with
subsequent loss of atrial contribution to ventricular diastolic
filling and nonphysiological pressure waves. In case of chronotropic incompetence in patients with sick sinus node with an
implanted 2- or 3-chamber device, a mode switch from DDD-R
to VVI/DDI without activation of rate response may lead to the
loss of chronotropic competence. In case of a dual-chamber
device and sinus bradycardia, a pacing-induced left bundlebranch block pattern of activation with subsequent mechanical
dyssynchrony can potentially lead to a loss of physical capacity. In the case of isolated atrial oversensing, a spontaneous VT
may be inadequately classified as supraventricular tachycardia.
If a supraventricular tachycardia time-out is not programmed,
no therapy would be delivered in case of VT.
Right Ventricular Disturbances
Ventricular interferences caused by the field exposure were
detected 20 times at maximum sensitivity and 5 times at
nominal sensitivity. Right ventricular disturbances may lead
to an inadequate detection of VT/VF and subsequent antitachycardia pacing or shock delivery. There is increasing evidence that inadequate shocks by themselves are associated
with worse prognosis, although a clear cause-effect relationship has not yet been proven.39 Some devices interpret these
signals, depending on the individual sensing algorithm, as an
artificial noise (eg, short intervals <120–130 milliseconds are
unlikely to be VF) and subsequently switch to a certain disturbance mode, which may be programmed at V00/D00/000.
However, in this case, a spontaneous VT/VF episode cannot
be detected. In cases of premature ventricular contractions or
intrinsic heart rates higher than the programmed pacing rate
of V00/D00, stimulation may lead to delivery of stimuli into
the T wave, carrying the risk of VT/VF induction. This is not
unlikely because strong EMFs occur mostly in occupational
environments when the patient may be under physical stress
and thus have an increased intrinsic heart rate and an overall
higher likelihood of VT/VF occurrence (eg, because of ischemia in coronary artery disease) and elevated serum catecholamine levels.
Shorter or pulsed noise episodes may not trigger VT/VF
detection and subsequent ICD therapy but may lead to pacing
inhibition in patients with pacemaker dependency, which may
cause symptomatic bradycardia or loss of resynchronization
efficacy in CRT patients.
Worst-Case Conditions
In Tables I and II in the online-only Data Supplement, worstcase conditions are shown for all interference thresholds
determined.
In terms of the atrial channel, sustained pacing affected the
interference thresholds in 15 of 41 runs (36.6%) under single or combined exposure. At full inspiration, the thresholds
decreased in 5 of 41 runs (12.2%). Both conditions had an
impact in 5 of 41 cases (12.2%).
For the ventricular channel, interference thresholds changed
in 30 of 33 exposures (90.9%) during pacing. Respiration
influenced the interference thresholds in only 1 patient (P095);
sustained pacing had no impact. Thus, the results support the
assumption of the influence of the worst-case conditions of
full inspiration and sustained pacing.
Our results further confirm previously obtained data from
pacemakers21 showing the influence of the programmable sensitivity on interference thresholds of ICDs. The susceptibility to
EMI was coupled with the sensitivity settings, that is, the lower
the sensitivity value, the lower the interference threshold of the
ICD and vice versa (in the same patient). However, different
patients with equal interference thresholds do not necessarily
have the same sensitivity settings (Tables I and II in the onlineonly Data Supplement). The impact of the sensitivity values
varies among manufacturers because of the manufacturer’s
specific automatic adjustment of the sensitivity threshold. For
example, when the ventricular disturbances of the Biotronik
and St. Jude Medical single-chamber ICDs were compared, the
data revealed that 4 of 26 tested Biotronik ICDs (15.4%) and
4 of 34 tested St. Jude Medical ICDs (11.8%) could be disturbed at sensitivity values of 0.5 and 0.2 mV, respectively.
Napp et al ICDs in Power Frequency Electromagnetic Fields 449
The susceptibility to EMI of an ICD is also influenced by
the type of lead and the patient’s physique.18,21 Table III in the
online-only Data Supplement gives details of the leads and
patient physique for all patients.
Potential Clinical Implications and Clinical
Management
Downloaded from http://circ.ahajournals.org/ by guest on June 15, 2017
It is important to identify patients at risk of EMI. If strong
EMF exposure is expected, particular care must be taken to
optimize the implantation procedure (maximum achievable
P/R potential). An ICD test with low-sensitivity settings has to
be considered. Moreover, regular control of the intrinsic signal
amplitudes (P/R wave) and the occurrence of EMIs via telemedicine transmitter is advisable.
It is not possible to define general sensitivity settings for
EMF protection because of several individual factors, including lead position, patient physique, and type of EMF source.
It remains a challenge for physicians to find a sensitivity level
that gives a good balance between reduced EMI and accurate
VT/VF sensing.
When inappropriate ICD discharges or episodes of EMI
occur, patients should be assessed carefully. The situation
of EMI occurrence should clearly be evaluated. Sometimes
onsite measurements of EMFs are necessary. In terms of minimal device sensitivity, adjustment should be combined with
ICD testing. Furthermore, patients should be tested in simulated EMFs, as in the present study.
In case of suddenly perceiving interference, increasing the
distance to sources of EMF is the first remedial action to stop
the dysfunction. Device defects caused by low-frequency
EMFs have not yet been documented.
Study Limitations
The present study was not designed to classify specific ICD
models concerning their susceptibility in EMF exposure situations. However, further investigations may identify patient-,
device-, and lead-related predictors of EMI.
Dual-chamber ICDs and CRT-Ds are underrepresented in
this study. Therefore, conclusions on atrial interferences are
not based on as many patients as for the right ventricular lead.
In addition, the uneven distribution of the number of implants
from each manufacturer may have influenced the results.
The validation of the electric field generation is based on
a method comparison with 6 volunteers (see the online-only
Data Supplement for details). Although the results indicate
good agreement between the 2 methods, the data should be
validated with a larger number of volunteers.
Furthermore, the findings of this study cannot be transferred
to EMI at intermediate frequency and radiofrequency. Finally,
the data are not applicable to pacemakers because of the difference in signal analysis of pacemakers and ICDs. Further
study focusing on pacemaker patients is necessary.
Conclusions
The findings indicate that extremely low-frequency EMFs of
everyday life do not disturb sensing capabilities of ICDs. The
limit values for the protection of humans exposed to EMFs in
general public assume to protect patients with ICDs at 50/60
Hz. In contrast, strong electric, magnetic, or combined fields
in certain occupational environments are capable of causing
undersensing or inappropriate sensing of atrial/ventricular
tachyarrhythmias. However, a correct device function can still
be expected in most cases. ICD devices with atrial sensing are
more susceptible to EMI than single-chamber systems. Pacing
in the ventricle increases the susceptibility to EMI.
In case of uncertainty about EMI, in vivo provocation
examination such as those described in this study can provide
a reliable and individual risk assessment for patients with
implanted devices.
Acknowledgments
We thank the volunteers who participated in this study and the EMFPortal team for the valuable contribution on the current status of publications on this topic and their editorial input to this manuscript.
Source of Funding
This study was funded through a grant from the German Social
Accident Insurance Institution for the energy, textile, electrical, and
media products sectors (BG ETEM) and the research unit for electropathology (FFE).
Disclosures
Drs Napp and Zink received travel grants from Biotronik, Boston
Scientific, Medtronic, and St. Jude Medical. Drs Knackstedt,
Bellmann, Marx, and Schauerte have received funding from
Biotronik, Boston Scientific, Medtronic, and St. Jude Medical for
consulting and lectures. The other authors report no conflicts.
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Clinical Perspective
To date, reliable systematic data on electromagnetic interferences on implantable cardioverter-defibrillators are scarce despite
a high potential clinical relevance. Current recommendations by the manufacturers are very conservative with respect to exposure of implantable cardioverter-defibrillator patients to electric and magnetic fields (EMFs). This is based on the assumption
that EMFs may lead to harmful interferences with the device. Recommendations on the code of behavior on how to handle
electric and magnetic field sources in everyday life are inconsistent and are not based on in vivo studies. Decision making for
implantable cardioverter-defibrillator implantation for the primary prevention in job-related EMF-exposed patients and subsequent recommendation of early retirement is often complex. National and international guidelines for the protection of humans
exposed to EMF exclude patients wearing electric cardiac implants. The present study shows that electromagnetic interferences
occur predominantly in relatively strong EMFs, which are normally present only in occupational environments. Moreover, we
demonstrate a strong dependency on the programmed sensitivity of the device. Additionally, our data suggest that individual
thresholds of electromagnetic interferences can be obtained and compared with the individual exposure of the patient. These
results are important for clinicians to optimize the implantation procedure to achieve maximum obtainable intracardiac electrogram potentials, to choose appropriate device programming, and to provide advice for the management of patients with foreseeable high EMF exposure. Nonetheless, further investigations are needed to investigate patient- and device-related predictors of
electromagnetic interferences. This may help to develop better sensing algorithms and to design new implantable cardioverterdefibrillator leads for the prevention of harmful electromagnetic interferences of implantable cardioverter-defibrillators.
Electromagnetic Interference With Implantable Cardioverter-Defibrillators at Power
Frequency: An In Vivo Study
Andreas Napp, Stephan Joosten, Dominik Stunder, Christian Knackstedt, Matthias Zink,
Barbara Bellmann, Nikolaus Marx, Patrick Schauerte and Jiri Silny
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Circulation. 2014;129:441-450; originally published online October 25, 2013;
doi: 10.1161/CIRCULATIONAHA.113.003081
Circulation is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231
Copyright © 2013 American Heart Association, Inc. All rights reserved.
Print ISSN: 0009-7322. Online ISSN: 1524-4539
The online version of this article, along with updated information and services, is located on the
World Wide Web at:
http://circ.ahajournals.org/content/129/4/441
Data Supplement (unedited) at:
http://circ.ahajournals.org/content/suppl/2013/10/25/CIRCULATIONAHA.113.003081.DC1
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1
SUPPLEMENTAL MATERIAL
Supplemental Methods
As stated in the manuscript the induced current in the thorax by exogenous electric fields can
be reproduced by direct current injection. For validation we conducted a test with 6 volunteers
applying real electric field exposure as well as direct current injection and compared the
induced voltage in the body.
The test was performed in the high voltage laboratory of the Institute for High Voltage
Technology at the RWTH Aachen University. We generated a real electric field with a special
high voltage electrode (O-shape, diameter 3 m). The electrode was connected to 50 Hz AC
voltage in order to create an environmental equivalent vertically oriented electric field as it
occurs e.g. under power lines.
Moreover 4 electrodes were placed on the shoulder/neck of the volunteers to directly supply
50 Hz AC currents as we did in the present study. Also 2 electrodes were placed on each leg.
With these electrodes the body current due to field induction, as well as direct injection, was
measured.
The two methods - real field exposure and direct current injection - were compared on the
basis of measurements in the body. Through esophagus catheters with sensing electrodes, the
induced voltage close to the apex of the right ventricle, was measured. Details about this
procedure can be found elsewhere.1
2
The volunteers were exposed for 30 seconds to different electric fields: 1 kV/m, 4 kV/m, 8
kV/m and 12 kV/m. The field strength was controlled as well as the induced body current and
the induced voltage was recorded continuously. In the same setting subsequent to real field
exposure, the direct current injection measurements were performed while AC currents of 40
μA und 90 μA were applied.
To compare the induced voltages of the measurement series the averaged peak value is
calculated and normalized to the particular body current. In Figure S1 the results are shown
for real field exposure and direct current injection. Depicted are the minimum, mean and
maximum values of the measurements. The variations are caused due to the nonlinear relation
between the body current and the induced voltage, as well as body movements, like
swallowing and muscle contractions. However, the results of the two methods are in the same
range, so therefore we conclude that direct current injection is a valid reproduction of real
electric field exposure.
3
Supplemental Tables
Table I. Interference of EMF with the atrial channel.
As explanation e.g. patient 36: The interference threshold of the patient’s Medtronic Consult CRT-D D234TRK was 30 kV/m in a single electric
field and 2.55 mT in a single magnetic field at maximum sensitivity (0.15 mV). Combined electric and magnetic fields the CRT-D could be
disturbed at 8.5 kV/m and 1.4 mT at maximum sensitivity. At nominal sensitivity (0.3 mV) no interference occurred under single field application,
however in combined fields the interference threshold was found at 30 kV/m and 2.55 mT.
Worst-case conditions
Single/Combined
Atrium lead
Manu-
Pacing
Model
facturer
DysAtrium
Patient
interference thresholds
(tip/ring
Full inspisensitivity*
mode
Mode‡
space) [mm]
E field
B field
ration
tion§
-1
[mV]
Biotronik
func-
[kVm ]
[mT]
Lexos DR-T
DDD
P017
10
0.2
S
No
30
1.8
AOS
Lumax 300 DR-T
DDD
P064
10
0.2
P
No
21.5
2.15
AOS
0.4†
P
Yes
27.1
2.55
AOS
0.2
S
No
30
1.4
AOS
0.4†
P
Yes
27.4
2.55
AOS
0.2
S
No
--
0.45
AOS
Lumax 540 DR-T
Lumax 540 DR-T
DDD
DDD
P085
P091
10
10
4
Guidant /
Ventak Prizm 2 DR DDD
Boston
1861
0.2
P
No
3.5
0.3
AOS
0.4†
S
No
--
0.64
AOS
0.4†
S
No
14
0.45
AOS
P050
17.8
0.18†
S
No
25.9
2.15
AOS
P056
17.8
0.18†
S
No
15
--
AOS
0.18†
S
No
--
0.8
AOS
0.18†
P
No
12
0.64
AOS
0.15
P
Yes
9
1.2
AOS
0.25†
P
No
9
1.4
AOS
0.15
S
No
30
--
AOS
0.15
S
No
--
2.55
AOS
0.15
S
No
8.5
1.4
AOS
0.3†
S
No
30
2.55
AOS
0.15
S
No
24.6
--
AOS
Scientific
Vitality2 T165DR
Teligen 100 F110
Medtronic
Consulta CRT-D
DDD
DDD
CRT-D
P105
P036
10
10
D234TRK
Consulta CRT-D
CRT-D
P069
10
5
D234TRK
Consulta CRT-D
0.15
P
No
16.5
1.8
AOS
CRT-D
P099
10
0.15
P
No
18.2
1.6
AOS
CRT-D
P070
10
0.15
S
No
25.6
--
AOS
0.15
S
No
21.1
1.8
AOS
D234TRK
InSync III Marquis
7279
InSync Maximo
CRT-D
P072
10
0.15
S
No
23
1.8
AOS
InSync Sentry 7298 CRT-D
P002
17.8
0.15†
P
No
28
1
AOS
Intrinsic 7288
P026
10
0.15
S
No
19.5
--
AOS
0.15
S
No
--
2.35
AOS
0.15
S
No
7.4
1.8
AOS
0.45†
P
No
25
1.8
AOS
0.15
S
No
23
--
AOS
0.15
S
No
--
1.9
AOS
0.15
S
No
10.5
1.1
AOS
0.15
S
No
--
0.94
AOS
7304
Protecta DR
DDD
DDD
P092
10
D364DRG
Protecta XT-DR
DDD
P103
8
6
Secura DR
0.15
S
No
8.9
0.8
AOS
0.6†
P
No
30
2.15
AOS
DDD
P079
10
0.3†
P
Yes
25.2
2
AOS
CRT-D
P073
10
0.2†
S
No
--
0.57
AOS
0.2†
S
No
13.6
0.64
AOS
D234DRG
St. Jude
Atlas + HF V-341
Medical
Promote Accel RF
CRT-D
P096
1.1
0.2†
P
Yes
30
2.55
AOS
CRT-D
P098
1.1
0.2†
P
No
29.6
2.55
AOS
3215-36
Promote Q
* nominal and maximum atrial sensitivity values specified by the manufacturer
nominal
maximum
Biotronik:
0.4 mV
0.2 mV
Boston Scientific:
0.25 mV
0.15 mV
Guidant:
0.18 mV
0.18 mV
Medtronic:
0.3 mV
0.15 mV
St. Jude Medical:
0.2 mV
0.2 mV
7
† nominal sensitivity (preset sensitivity programmed by the treating physician)
‡ P: exposure during sustained pacing - S: exposure during intrinsic heart rate
§ AOS: atrial over sense
8
Table II. Interference of EMF with the ventricular channel.
Worst-case conditions
Single/Combined
Lead (tip/ring space)
Manu-
Pacing
Model
facturer
[mm]
Ventricle
sensitivity*
Mode‡
ventricle
Scientific
func-
E field
B field
[kVm-1]
[mT]
tion§
ration
ventricle
Lexos VR-T
VVI
P043
9
--
0.5
P
No
26.8
2.55
VOS
Lexos VR-T
VVI
P066
9
--
0.5
P
No
27.1
2.55
VOS
Lumax 300 VR-T
VVI
P055
11.5
--
0.5
P
No
--
0.8
VOS
0.5
P
No
29.8
0.8
VOS
0.8†
P
No
25.5
0.9
VOS
No
--
--
Lumax 300 HF-T
Boston
thresholds
inspi-
Left
[mV]
Guidant /
Dys-
Patient
mode
Right
Biotronik
interference
Full
CRT-D
Ventak Prizm 2 VR VVI
P077
P076||
11.5
12
18
--
0.5 (RV)
0.5 (LV)
P
No
--
2
LVI
0.18
P
No
--
1.8
VOS
9
Ventak Prizm VR
VVI
P016
12
--
0.18
P
No
30
2.55
VOS
Vitality 2T175VR
VVI
P063
12
--
0.18
P
No
16.4
1.8
VOS
Vitality 2T175VR
VVI
P104
12
--
0.18
P
No
--
0.6
VOS
0.18
P
No
25.6
0.5
VOS
0.27†
P
No
--
2
VOS
0.27†
P
No
30
2.15
VOS
0.15
P
No
--
2.15
VOS
0.15
P
No
28.3
1.9
VOS
0.15
S
No
--
1.66
VOS
0.15
P
No
30
1.53
VOS
HE
Medtronic
Consulta CRT-D
CRT-D
P028
8
21
D234TRK
EnTrust Escudo
VVI
P093
8
--
D144VRC
GEM III VR 7231
VVI
P045
8
--
0.15
P
No
27.3
2.55
VOS
GEM III VR 7231
VVI
P095
8
--
0.15
S
Yes
25.5
2.55
VOS
Marquis 7230Cx
VVI
P097
8
--
0.15
S
No
--
1.8
VOS
0.15
P
No
30
1.4
VOS
0.3†
P
No
29.8
2.55
VOS
10
Maximo VR 7232
VVI
P029
8
--
0.15
P
No
21.3
1.4
VOS
0.3†
P
No
25.6
1.4
VOS
Maximo VR 7232
VVI
P053
8
--
0.15
P
No
30
2.55
VOS
Protecta DR
DDD
P092
8
--
0.3†
P
No
16.7
1.8
VOS
VVI
P088
8
--
0.15
P
No
30
2.3
VOS
Atlas+ VR V-193
VVI
P033||
11
--
0.2
P
No
--
1.4
VOS
Atlas+ VR V-193
VVI
P065
11
--
0.2
P
No
--
2
VOS
0.2
P
No
29.9
2.15
VOS
D364DRG
Virtuoso VR
D164VWC
St. Jude
Medical
Atlas+ VR V-193
VVI
P068
11
--
0.2
P
No
21
2.15
VOS
Atlas II VR V-168
VVI
P102
11
--
0.2
P
No
--
2.55
VOS
0.2
P
No
29.9
2.55
VOS
* nominal and maximum ventricular sensitivity values specified by the manufacturer
11
nominal
maximum
Biotronik:
RV 0.8 mV/LV 1.6 mV
RV 0.5mV/LV 0.5 mV
Boston Scientific:
RV 0.6 mV
RV 0.15 mV
Guidant:
RV 0.27 mV/LV 1.24 mV
RV 0.18 mV/LV 0.62 mV
Medtronic:
RV 0.3 mV
RV 0.15mV
St. Jude Medical:
RV 0.3 mV
RV 0.2 mV
† nominal sensitivity (preset sensitivity programmed by the treating physician)
‡ P: exposure during sustained pacing - S: exposure during intrinsic heart rate
§ VOS: ventricular over sense - LVI: left ventricular inhibition
|| Was not further tested under combined field settings due to time constraints of the patients.
12
Table III. Details of all 110 patients regarding their ICD models, the tip to ring space of the leads and the patient’s weight, height and age.
Lead (tip/ring
Manu-
Pacing
Model
facturer
Biotronik
Age
Patient
space) [mm]
Gender
mode
Height [m]
Weight [kg]
[years]
A*
RV†
LV‡
Lexos VR-T
VVI
P005
--
11.5
--
male
59
1.87
84
Lexos VR-T
VVI
P007
--
9
--
male
60
1.76
98
Lexos VR-T
VVI
P042
--
9
--
female
54
1.67
70
Lexos VR-T
VVI
P043
--
9
--
male
67
1.72
94
Lexos VR-T
VVI
P066
--
9
--
female
69
1.62
65
Lexos VR-T
VVI
P046
--
9
--
male
55
1.73
104
Lexos DR-T
DDD
P017
10
9
--
male
61
1.89
78
Lumax 300 VR-T
VVI
P062
--
11
--
male
34
1.93
82
Lumax 300 VR-T
VVI
P055
--
11.5
--
male
72
1.70
81
Lumax 300 VR-T
VVI
P074
--
11.5
--
male
74
1.86
89
Lumax 300 DR-T
DDD
P064
10
11
--
male
75
1.84
91
Lumax 300 HF-T
CRT-D
P077
10
11.5
18
female
57
1.72
106
13
Guidant /
Boston
Lumax 340 VR-T
VVI
P021
--
11
--
male
51
1.78
86
Lumax 340 VR-T
VVI
P083
--
11
--
male
67
1.72
82
Lumax 340 HF
CRT-D
P060
10
11
female
69
1.57
62
Lumax 500 VR-T
VVI
P071
--
9
--
male
60
1.90
121
Lumax 540 VR-T
VVI
P004
--
11
--
male
31
1.84
84
Lumax 540 VR-T
VVI
P011
--
9
--
male
73
1.74
83
Lumax 540 VR-T
VVI
P030
--
11
--
male
49
1.80
105
Lumax 540 VR-T
VVI
P031
--
11
--
male
65
1.86
99
Lumax 540 VR-T
VVI
P051
--
11
--
male
62
1.68
62
Lumax 540 VR-T
VVI
P054
--
11
--
male
73
1.80
93
Lumax 540 VR-T
VVI
P082
--
11
--
male
71
1.78
73
Lumax 540 DR-T
DDD
P085
10
9
--
male
75
1.74
71
Lumax 540 DR-T
DDD
P091
10
11
--
male
52
1.75
105
Lumos VR-T
VVI
P009
--
11.5
--
male
56
1.80
90
Prizm VR HE 1857
VVI
P058
--
12
--
female
53
1.75
100
14
Scientific
Medtronic
Punctua F050
VVI
P108
--
12
--
male
54
1.80
100
Teligen 100 F102
VVI
P067
--
12
--
male
50
1.76
78
Teligen 100 F110
DDD
P105
10
12
--
male
52
1.83
98
Teligen 100 F110
DDD
P109
10
11
--
male
54
1.80
74
Ventak Prizm 2 VR
VVI
P014
--
11
--
male
63
1.73
96
Ventak Prizm 2 VR
VVI
P076
--
12
--
female
55
1.65
57
Ventak Prizm VR HE
VVI
P016
--
12
--
male
47
1.88
83
Ventak Prizm 2 DR 1861
DDD
P050
17.8
12
--
male
59
1.72
78
Vitality 2 T175 VR
VVI
P018
--
12
--
male
45
1.73
71
Vitality 2 T175VR
VVI
P078
--
12
--
male
56
1.88
104
Vitality 2 T175VR
VVI
P104
--
12
--
male
40
1.86
94
Vitality 2 T175 VR
VVI
P063
--
12
--
male
53
1.82
95
Vitality 2 T165 DR
DDD
P056
17.8
12
--
male
59
1.63
84
Consulta CRT-D D234TRK
CRT-D
P006
10
8
11
male
56
1.86
98
Consulta CRT-D D234TRK
CRT-D
P028
10
8
21
male
70
1.80
80
15
Consulta CRT-D D234TRK
CRT-D
P036
10
8
11
male
58
1.84
96
Consulta CRT-D D234TRK
CRT-D
P069
10
8
11
male
71
1.68
71
Consulta CRT-D D234TRK
CRT-D
P099
10
8
21
female
51
1.55
112
EnTrust Escudo D144VRC
VVI
P093
--
8
--
male
45
1.93
76
GEM III VR 7231
VVI
P013
--
9
--
male
41
1.81
82
GEM III VR 7231
VVI
P020
--
9
--
male
62
1.86
94
GEM III VR 7231
VVI
P023
--
9
--
male
55
1.82
102
GEM III VR 7231
VVI
P037
--
12
--
male
66
1.75
90
GEM III VR 7231
VVI
P039
--
9
--
male
54
1.65
68
GEM III VR 7231
VVI
P044
--
9
--
male
56
1.70
83
GEM III VR 7231
VVI
P045
--
8
--
male
59
1.86
89
GEM III VR 7231
VVI
P049
--
9
--
male
65
1.70
73
GEM III VR 7231
VVI
P095
--
8
--
male
67
1.80
108
InSync III Marquis 7279
CRT-D
P061
10
8
female
62
1.60
88
InSync III Marquis 7279
CRT-D
P070
10
8
male
56
1.76
79
InSync Maximo 7304
CRT-D
P072
10
8
male
59
1.85
83
11
16
InSync Sentry 7298
CRT-D
P002
17.8
8
11
female
50
1.85
72
Intrinsic 7288
DDD
P026
10
8
--
male
49
1.86
84
Marquis 7230Cx
VVI
P097
--
8
--
male
71
1.76
64
Maximo VR 7232
VVI
P003
--
8
--
male
22
1.68
67
Maximo VR 7232
VVI
P029
--
8
--
female
47
1.75
62
Maximo VR 7232
VVI
P053
--
8
--
male
71
1.70
70
Protecta VR D364VRG
VVI
P110
--
8
--
male
63
1.65
81
Protecta DR D364DRG
DDD
P092
10
8
--
male
69
1.71
71
Protecta XT-DR
DDD
P103
8
10
--
male
38
1.80
110
Secura VR D234VRC
VVI
P008
--
8
--
male
45
1.83
94
Secura VR D234VRC
VVI
P048
--
12
--
male
67
1.75
108
Secura DR D234DRG
DDD
P079
10
8
--
male
51
1.80
85
Secura VR D234VRC
VVI
P084
--
8
--
male
56
1.81
120
Secura VR D234VRC
VVI
P086
--
8
--
female
41
1.53
55
Virtuoso VR D164VWC
VVI
P059
--
8
--
male
55
1.83
99
Virtuoso VR D164VWC
VVI
P080
--
8
--
female
66
1.68
61
17
St. Jude
Virtuoso VR D164VWC
VVI
P088
--
8
--
male
70
1.76
77
Virtuoso VR D164VWC
VVI
P100
--
8
--
female
52
1.68
73
Analyst Accel VR 1219-36
VVI
P047
--
11
--
male
59
1.79
95
Analyst Accel VR 1219-36
VVI
P025
--
11
--
male
49
1.80
94
Atlas + VR V-193
VVI
P019
--
11
--
male
63
1.75
84
Atlas + VR V-193
VVI
P033
--
11
--
male
59
1.76
81
Atlas + VR V-193
VVI
P038
--
11
--
male
56
1.82
90
Atlas + VR V-193
VVI
P041
--
11
--
male
56
1.80
96
Atlas + VR V-193
VVI
P065
--
11
--
female
47
1.70
85
Atlas + VR V-193
VVI
P068
--
11
--
male
53
1.72
95
Atlas + VR V-193
VVI
P101
--
11
--
male
68
1.70
85
Atlas + HF V-341
DDD
P015
10
11
--
male
54
1.86
95
Atlas + HF V-341
CRT-D
P073
10
11
male
68
1.81
83
Atlas DR V-242
VVI
P090
--
11
--
male
62
1.72
115
Atlas II + DR V-268
DDD
P057
10
11
--
female
36
1.68
50
Medical
18
Atlas II VR V-168
VVI
P001
--
11
--
male
30
1.73
59
Atlas II VR V-168
VVI
P010
--
11
--
male
57
1.68
78
Atlas II VR V-168
VVI
P012
--
11
--
male
48
1.76
76
Atlas II VR V-168
VVI
P024
--
11
--
male
51
1.85
94
Atlas II VR V-168
VVI
P032
--
11
--
male
70
1.72
74
Atlas II VR V-168
VVI
P034
--
11
--
female
49
1.70
75
Atlas II VR V-168
VVI
P035
--
11
--
male
63
1.65
86
Atlas II VR V-168
VVI
P040
--
11
--
male
66
1.80
94
Atlas II VR V-168
VVI
P052
--
11
--
female
67
1.58
60
Atlas II VR V-168
VVI
P075
--
11
--
male
60
1.80
97
Atlas II VR V-168
VVI
P081
--
11
--
male
68
1.80
74
Atlas II VR V-168
VVI
P102
--
11
--
male
22
1.83
60
Current VR RF 1207-36
VVI
P094
--
11
--
male
71
1.68
87
Current + VR CD1211-36Q
VVI
P107
--
11
--
male
49
1.84
90
Current + DR CD2211-36
DDD
P089
10
11
--
male
30
1.96
104
Current Accel VR CD1215-36
VVI
P087
--
11
--
male
53
1.72
108
19
Fortify VR 1233-40Q
VVI
P106
--
11
--
male
56
1.68
97
Promote Accel RF 3215-36
DDD
P022
1.1
11
--
male
61
1.75
97
Promote Accel RF 3215-36
CRT-D
P096
1.1
11
20
female
69
1.64
80
Promote RF 3213-16
CRT-D
P027
10
11
20
male
60
1.86
71
Promote Q
CRT-D
P098
1.1
11
27
female
74
1.63
62
* Atrium
† Right ventricle
‡ Left ventricle
20
Supplemental Figures
Figure I. Comparison of minimum, mean and maximum value of the induced voltages
normalized to the body current for real field exposure and direct current injection of 6
volunteers.
Supplemental References
1. Joosten S, Pammler K, Silny J. The influence of anatomical and physiological parameters
on the interference voltage at the input of unipolar cardiac pacemakers in low frequency
electric fields. Physics in medicine and biology. 2009;54(3):591–609.