Implantable cardioverter defibrillators and cellular telephones: is there any interference?

New-generation electronic appliances and cardiac implantable electronic devices: a systematic literature review of mechanisms and in vivo studies

INTRODUCTION

Cardiac implantable electronic device (CIED) functions are susceptible to electromagnetic interference (EMI) from electromagnetic fields (EMF). Data on EMI risks from new-generation electronic appliances (EA) are limited.

OBJECTIVE

We performed a systematic literature review on the mechanisms of EMI, current evidence, and recently published trials evaluating the effect of EMF on CIEDs from electric vehicles (EV), smartphone, and smartwatch technology and summarize its safety data.

METHODS

Electronic databases, including PubMed and EMBASE, were searched for in vivo studies evaluating EMF strength and incidence between CIEDs and commercial EVs, new-generation smartphones, and new-generation smartwatches.

RESULTS

A total of ten studies (three on EVs, five on smartphones, one on smartphones, one on smartphones and smartwatches) were included in our systematic review. There was no report of EMI incidence associated with EVs or smartwatches. Magnet-containing smartphones (iPhone 12) can cause EMI when placed directly over CIEDs - thereby triggering the magnet mode; otherwise, no report of EMI was observed with other positions or smartphone models.

CONCLUSION

Current evidence suggests CIED recipients are safe from general interaction with EVs/HEVs, smartphones, and smartwatches. Strictly, results may only be applied to commercial brands or models tested in the published studies. There is limited data on EMI risk from EVs wireless charging and smartphones with MagSafe technology.

Low risk of electromagnetic interference between smartphones and contemporary implantable cardioverter defibrillators

AIMS

Manufacturers of implantable cardioverter defibrillators (ICDs) recommend that cell phones be maintained at a distance of ∼15 cm from the implanted device in order to avoid risk of dysfunction due to electromagnetic interference (EMI). Data relating to this issue are outdated and do not reflect modern technology. Our aim was to evaluate whether EMI is still an issue with contemporary ICDs and smartphones.

METHODS AND RESULTS

Consecutive patients implanted with a wireless-enabled ICD were tested for potential interference with two models of recent 4G smartphones in conditions intended to maximize risk of EMI. A magnet effect (due to the phone speakers) was tested by placing the smartphones in the standby mode directly over the ICD generator. The presence of EMI artefacts on the real-time electrograms was evaluated by placing the smartphones in the standby, dialling, and operating modes directly over the generator casing and over the parasternal region in the vicinity of the ventricular lead. A total of 63 patients equipped with 29 different models of single, dual, or biventricular ICDs from five major manufacturers were included. None of the patients showed any evidence of interference with the smartphones during any of the 882 tests.

CONCLUSION

The risk of EMI between modern smartphones and contemporary ICDs is low. This is probably due to the filters incorporated in the ICDs and low emission by the phones, as well as the small size of the magnets in the smartphones tested.

STUDY REGISTRATION

NCT02330900 (http://www.clinicaltrials.gov).

Effects of external electrical and magnetic fields on pacemakers and defibrillators: from engineering principles to clinical practice

The overall risk of clinically significant adverse events related to EMI in recipients of CIEDs is very low. Therefore, no special precautions are needed when household appliances are used. Environmental and industrial sources of EMI are relatively safe when the exposure time is limited and distance from the CIEDs is maximized. The risk of EMI-induced events is highest within the hospital environment. Physician awareness of the possible interactions and methods to minimize them is warranted.

In vitro assessment of the immunity of implantable cardioverter-defibrillators to magnetic fields of 50/60 Hz

Public concern for the compatibility of electromagnetic (EM) sources with active implantable medical devices (AIMD) has prompted the development of new systems that can perform accurate exposure studies. EM field interference with active cardiac implants (e.g. implantable cardioverter-defibrillators (ICDs)) can be critical. This paper describes a magnetic field (MF) exposure system and the method developed for testing the immunity of ICD to continuous-wave MFs. The MFs were created by Helmholtz coils, housed in a Faraday cage. The coils were able to produce highly uniform MFs up to 4000 µT at 50 Hz and 3900 µT at 60 Hz, within the test space. Four ICDs were tested. No dysfunctions were found in the generated MFs. These results confirm that the tested ICDs were immune to low frequency MFs.

Electromagnetic interference and implanted cardiac devices: the nonmedical environment (part I)

The number of patients with cardiovascular implantable electronic devices (CIEDs), such as permanent pacemakers and implantable cardioverter-defibrillators, is dramatically rising due to an aging population and recent clinical trials showing benefits in mortality and morbidity. Coupled with this increase in the number of patients with CIEDs is the proliferation of technology that emits electromagnetic signals, which can potentially interfere with CIED function through electromagnetic interference (EMI). Despite continuous efforts of manufacturers to create "EMI-proof" CIEDs, adverse events from EMI still occur. Physicians caring for patients with CIEDs should be aware of potential sources of EMI and appropriate management options. This 2-part review aims to provide a contemporary overview of the current knowledge regarding risks attributable to EMI interactions from the most common nonmedical (Part I) and medical (Part II) sources.

Do mobile phones pose a potential risk to autonomic modulation of the heart?

BACKGROUND

It has long been speculated that mobile phones may interact with the cardiac devices and thereby cardiovascular system may be a potential target for the electromagnetic fields emitted by the mobile phones. Therefore, the present study was designed to test possible effects of radiofrequency waves emitted by digital mobile phones on cardiac autonomic modulation by short-time heart rate variability (HRV) analysis.

METHODS AND RESULTS

A total of 20 healthy young subjects were included to the study. All participants were rested in supine position at least for 15 minutes on a comfortable bed, and then time and frequency domain HRV parameters were recorded at baseline in supine position for 5 minutes. After completion of baseline records, by using a mobile GSM (Global System for Mobile Communication) phone, HRV parameters were recorded at turned off mode, at turned on mode, and at calling mode over 5 minutes periods for each stage.

CONCLUSION

Neither time nor frequency domain HRV parameters altered significantly during off mode compare to their baseline values. Also, neither time nor frequency domain HRV parameters altered significantly during turned on and calling mode compared to their baseline values. Short-time exposure to electromagnetic fields emitted by mobile phone does not affect cardiac autonomic modulation in healthy subjects.

Patient safety and electromagnetic protection: a review

A systematic literature review was carried out to study patient security and possible harmful effects, immunity and interferences on medical devices, and effectiveness and transmission problems in healthcare and hospital environments due to electromagnetic interferences. The objective was to determine already-reported cases of patient security, immunity of medical devices, and transmission/reception failure in order to evaluate safety and security of patients. Literature published in the last 10 years has been reviewed by searching in bibliographic databases, journals, and proceedings of conferences. Search strategies developed in electronic databases identified a total of 820 references, with 50 finally being included. The study reveals the existence of numerous publications on interferences in medical devices due to radiofrequency fields. However, literature on effectiveness, transmission problems and measurements of electromagnetic fields is limited. From the studies collected, it can be concluded that several cases of serious interferences in medical instruments have been reported. Measures of electromagnetic fields in healthcare environments have been also reported, concluding that special protective measures should be taken against electromagnetic interferences by incoming radio waves.

Third-generation mobile phones (UMTS) do not interfere with permanent implanted pacemakers

AIMS

Third-generation mobile phones, UMTS (Universal Mobile Telecommunication System), were recently introduced in Europe. The safety of these devices with regard to their interference with implanted pacemakers is as yet unknown and is the point of interest in this study.

METHODS AND RESULTS

The study comprised 100 patients with permanent pacemaker implantation between November 2004 and June 2005. Two UMTS cellular phones (T-Mobile, Vodafone) were tested in the standby, dialing, and operating mode with 23 single-chamber and 77 dual-chamber pacemakers. Continuous surface electrocardiograms (ECGs), intracardiac electrograms, and marker channels were recorded when calls were made by a stationary phone to cellular phone. All pacemakers were tested under a "worst-case scenario," which includes a programming of the pacemaker to unipolar sensing and pacing modes and inducing of a maximum sensitivity setting during continuous pacing of the patient. Patients had pacemaker implantation between June 1990 and April 2005. The mean age was 68.4 +/- 15.1 years. Regardless of atrial and ventricular sensitivity settings, both UMTS mobile phones (Nokia 6650 and Motorola A835) did not show any interference with all tested pacemakers. In addition, both cellular phones did not interfere with the marker channels and the intracardiac ECGs of the pacemakers.

CONCLUSION

Third-generation mobile phones are safe for patients with permanent pacemakers. This is due to the high-frequency band for this system (1,800-2,200 MHz) and the low power output between 0.01 W and 0.25 W.

Effects of electromagnetic interference on implanted cardiac devices and their management

Potential interference between implanted cardiac devices such as pacemakers and implantable cardioverter-defibrillators and electromagnetic fields is an important concern for physicians taking care of patients with pacemakers and implantable cardioverter-defibrillators. There are many sources of electromagnetic interference (EMI); however, only a small number of these cause significant problems that need attention. Regardless of its source, EMI is of greater concern for a patient who is dependent on paced rhythm because inhibition of the pacemaker by EMI may produce ventricular standstill. It is important that cardiologists, internists, emergency medicine, critical care physicians, and anesthesiologists be aware of how EMI can affect the function of implanted cardiac devices so that appropriate treatment can be rendered and preventive measures instituted.

Inappropriate implantable cardioverter-defibrillator discharges unrelated to supraventricular tachyarrhythmias

AIMS

The development of implantable cardioverter-defibrillators (ICDs) with QRS morphology discrimination and dual-chamber sensing capabilities has improved the differentiation of supraventricular from ventricular tachycardias (VTs). Inappropriate ICD discharges may result from extracardiac signals caused by electromagnetic interference (EMI), because of electric fields and leakage currents from domestic or medical electrical devices, damaged sensing leads, and various cardiac and extracardiac signals that mimic VT and/or ventricular fibrillation. The aim of our study was to determine retrospectively the incidence and clinical relevance of these ICD behaviours and offer possible therapeutic solutions.

METHODS AND RESULTS

We have observed inappropriate discharges unrelated to supraventricular arrhythmias in 13 (3.9%) of the 336 patients implanted with ICDs in our centre from 1989 to 2005. Seven patients received inappropriate shocks following exposure to external EMI: improperly grounded electric stove, electrically powered watering system, hydro-massage bath, electrical pruner, electrocautery current during cardiac surgery, transcutaneous electric nerve stimulation. In four patients, spurious discharges were related to internal noise of the ICD system from inappropriate lead connections. In two cases, erroneous antitachycardia therapy was delivered following different body signals oversensing (T-wave oversensing, wide QRS double-counting and myopotentials). In nine patients, non-invasive solutions prevented further inappropriate therapies (avoidance of EMI, malfunctioning atrial lead exclusion, ventricular sensing reprogramming). In four patients, surgical revision of the system was required (lead connections or position revision).

CONCLUSION

In our experience, inappropriate ICD discharges unrelated to supraventricular arrhythmias occurred in about 4% of ICD patients. A careful evaluation of clinical data and telemetric information (lead impedance, sensed R-wave, stored electrograms) is essential in order to understand the nature of inappropriate ICD discharges and to select the most appropriate solution.

Effects of mobile telephones on the function of implantable cardioverter defibrillators

OBJECTIVE

We investigated whether mobile telephones affect the function of implantable cardioverter defibrillators (ICDs).

BACKGROUND

It is well known that electromagnetic fields can affect medical devices.

METHODS

The study included 43 patients with ventricular tachycardia and/or fibrillation treated with transvenous pectoral ICDs. Testing was done under continuous electrocardiograph monitoring under supervision of an ICD programmer. Initially, each patient was tested during spontaneous rhythm. Then the ICD was programmed to a pace rhythm higher than the patient's heart rate, and the tests were repeated at paced rhythm. In 7 patients, tests were performed during the implantation procedure as well. In 3 of the patients, only a single defibrillation zone was active. The other 40 patients had one or more active ventricular tachycardia zones. Two mobile phones (both GSM 900 MHz) were positioned 50 cm away from the implanted device in opposite directions and switched on. Communication was established between these phones, two investigators had a 20-second conversation, and then the phones were switched off. The same procedure was repeated at 30, 20, and 10 cm away from the implantation site, respectively. Finally, the procedure was performed with the antennae of both phones touching the device pocket. In the above-mentioned 7 cases where testing was done during implantation of the ICD, a call was made from one phone to the other, ringing occurred for 5 seconds, and then two investigators conversed while the device was implanted.

RESULTS

There was no change in the function of the ICDs during any of the phone testing procedures. In 5 cases, artifacts were noted on the surface electrocardiographic (ECG) screen of the programmer during the tests, but no such changes were observed on the simultaneous intracardiac ECGs.

CONCLUSION

The results of the study suggest that mobile phones have no effects on ICD function.

Safety of wireless capsule endoscopy in patients with implantable cardiac defibrillators

OBJECTIVES

Wireless video capsule endoscopy (CE) is a new technology that allows visualization of the entire small intestinal mucosa. It is indicated for the evaluation of obscure gastrointestinal bleeding (OGIB) and other disorders of the small intestine. Studies to date suggest that CE is safe and associated with few adverse events. A concern, which has not been studied, is the potential effect of CE on implanted cardiac devices such as implantable cardiac defibrillators (ICD) and other electromedical devices. We previously found CE to be safe in patients with cardiac pacemakers. The primary aim of this study was to evaluate the safety of CE in patients with ICDs who were being evaluated for OGIB. In addition, a secondary aim of the study was to determine whether ICDs had any effect on the images captured by CE.

METHODS

Patients referred for the evaluation of OGIB and who also had an ICD were enrolled into the study after informed consent. Five consecutive patients (four females and one male; mean age: 72 yr; range: 60-81 yr) with ICDs were studied. All patients had transvenous endocardial ICDs located in the chest. Prior to CE, patients had a baseline electrocardiogram (ECG) and ICD interrogation. Thereafter, CE was performed in a hospital setting with telemetry monitoring performed simultaneously. A post-procedure ICD interrogation was carried out to evaluate changes in programmed parameters. A cardiologist and ICD nurse specialist together reviewed both the telemetry monitor and the post-procedure ICD interrogation on each patient. When CE studies were reviewed, observations pertaining to technical difficulties and interference with video imaging were documented.

RESULTS

No arrhythmia or other adverse cardiac events were noted during capsule transmission. No interference by the ICD on the CE video images was seen.

CONCLUSIONS

CE was performed safely in these five patients with ICDs, and was not associated with any adverse cardiac events. ICDs also do not appear to interfere with video capsule imaging.

Influence des champs électromagnétiques non ionisants sur les dispositifs cardiaques médicaux implantables

AN INCREASINGLY FREQUENT PROBLEM: Since sources of electromagnetic interferences can alter the functioning of pacemakers (PM) and implantable cardioverter-defibrillators (ACD) are increasing and cover wide range of frequencies, from 0 to 300 GHz, including very low (VLF) and radio-frequencies (RF), carriers of such devices can suffer from decreased quality of life, without clinical impact, or even dangerous situations. PACEMAKERS: Pacemakers and implantable cardioverter-defibrillators are usually well protected from external interference. With pacemakers, such problems are handled fairly well and the consequences are usually benign. REGARDING DEFIBRILLATION: An interference can result in the inappropriate functioning of the device, the first consequence of which is an unexpected shock for the patient or, conversely, the lack of effective treatment when the patient most needs it. With ICD, the data in the literature suggest more attention should be paid, notably with anti-theft detector gates.

Electronic medical devices: a primer for pathologists

CONTEXT

Electronic medical devices (EMDs) with downloadable memories, such as implantable cardiac pacemakers, defibrillators, drug pumps, insulin pumps, and glucose monitors, are now an integral part of routine medical practice in the United States, and functional organ replacements, such as the artificial heart, pancreas, and retina, will most likely become commonplace in the near future. Often, EMDs end up in the hands of the pathologist as a surgical specimen or at autopsy. No established guidelines for systematic examination and reporting or comprehensive reviews of EMDs currently exist for the pathologist.

OBJECTIVE

To provide pathologists with a general overview of EMDs, including a brief history; epidemiology; essential technical aspects, indications, contraindications, and complications of selected devices; potential applications in pathology; relevant government regulations; and suggested examination and reporting guidelines.

DATA SOURCES

Articles indexed on PubMed of the National Library of Medicine, various medical and history of medicine textbooks, US Food and Drug Administration publications and product information, and specifications provided by device manufacturers.

STUDY SELECTION

Studies were selected on the basis of relevance to the study objectives.

DATA EXTRACTION

Descriptive data were selected by the author.

DATA SYNTHESIS

Suggested examination and reporting guidelines for EMDs received as surgical specimens and retrieved at autopsy.

CONCLUSIONS

Electronic medical devices received as surgical specimens and retrieved at autopsy are increasing in number and level of sophistication. They should be systematically examined and reported, should have electronic memories downloaded when indicated, will help pathologists answer more questions with greater certainty, and should become an integral part of the formal knowledge base, research focus, training, and practice of pathology.

Do airport metal detectors interfere with implantable pacemakers or cardioverter-defibrillators?

OBJECTIVES

The aim of this study was to determine whether airport metal detector gates (AMDGs) interfere with pacemakers (PMs) or implantable cardioverter-defibrillators (ICDs).

BACKGROUND

It is currently unknown whether AMDGs interfere with implanted PMs or ICDs.

METHODS

A total of 348 consecutive patients (200 PM and 148 ICD recipients) have been tested for the occurrence of electromagnetic interference (EMI) within the electromagnetic field of a worldwide-used airport metal detector.

RESULTS

No interference, such as pacing or sensing abnormalities, was observed in any of the 200 PM and 148 ICD patients; also no reprogramming occurred.

CONCLUSIONS

In vivo testing of PM and ICD systems showed no EMI with a standard AMDG. Clinically relevant interactions with implanted PMs or ICDs seem unlikely.

Mobile phones in the hospital--past, present and future

The phenomenon of electromagnetic interference by mobile phones is real and potentially clinically significant. This has been recognised by the Department of Health and the Medical Devices Agency, leading to bans on phone use in hospitals. Current evidence suggests that mobile phones can cause malfunction of medical equipment, but only when used in close proximity. Allowing phone use in non-patient care areas and improving staff education may improve compliance with hospital policies.

Influence of mobile phones on accuracy of ECG interpretation algorithm in automated external defibrillator

BACKGROUND

Automated External Defibrillators (AED) are a recommended tool for out-of-hospital emergency medical services. Mobile phones (GSM) are a potential source of electromagnetic interference which may cause failure of ECG interpretation and subsequent inappropriate action of AED's.

METHODS

We evaluated the influence of 900 MHz GSM phones on the accuracy of automatic ECG interpretation with a GSM Mobile Station Tester with adjustable power and mode of transmission (Hewlett-Packard HP5515A), GSM phones (Alcatel, Ericsson, Nokia, Panasonic), ECG simulator (Metron) and four AEDs (Fore Runner-Hewlett-Packard, Heartstart 3000-Laerdal, Cardio-Aid 100-Artema, Heartstream XLT-Agilent). The protocol included 18 different ECG patterns, different ECG voltages, and different power and mode of transmission.

RESULTS

The first stage of the protocol included minimal power of signal transmitted from GSM Mobile Station Tester and maximum power of GSM phone's signal--hence maximal potential interference to AED. The protocol was based on close direct contact between the GSM phone and the AED device. Regardless of the ECG pattern, with both 0.5 and 1.0 mV ECG voltage, and the GSM phone placed on various parts of AED device or at the patient cable, no failure of AED algorithm occurred. No detectable noise was seen at AED's ECG display.

CONCLUSION

AEDs seems to be well protected against clinically significant failure caused by noise from 900 MHz GSM phones.

Current status of the implantable cardioverter-defibrillator

Clinical trials have established the superiority of the implantable cardioverter-defibrillator (ICD) over antiarrhythmic drug therapy in survivors of sudden cardiac death and in high-risk patients with coronary artery disease. The ICD has evolved to overcome the limitation of earlier devices that required thoracotomy for implantation and were fraught with inappropriate shock delivery. Current ICDs are implanted in a similar manner to cardiac pacemakers and incorporate sophisticated rhythm-discrimination algorithms to prevent inappropriate therapy. Managing the patient with an ICD requires an understanding of the multiprogrammable features of modern devices. Drug interactions and potential sources of electromagnetic interference may adversely affect ICD function. Driving restrictions may be necessary under certain conditions. The cost-effectiveness of ICD therapy appears favorable, given the marked survival benefit seen in randomized trials relative to antiarrhythmic drug treatment. The growing number of ICD recipients necessitates an understanding of the specialized features of the modern ICD and the role of device therapy in clinical practice.

Epidemiological evidence on health risks of cellular telephones

It is too soon for a verdict on the health risks from cellular telephones, especially in view of changing technology. From the Interphone project and some other large studies in progress, better information may emerge. Based on the epidemiological evidence available now, the main public-health concern is clearly motor vehicle collisions, a behavioural effect rather than an effect of radiofrequency exposure as such. Neither the several studies of occupational exposure to radiofrequencies nor the few of cellular telephone users offer any clear evidence of an association with brain tumours or other malignancies. Even if the studies in progress were to find large relative effects for brain cancer, the absolute increase in risk would probably be much smaller than the risk stemming from motor vehicle collisions. Cellular telephones affect the quality of our lives in myriad ways, for good and ill; the health risk is just one part of a picture that is slowly coming into focus.