Electrical devices can create electromagnetic fields. Electricity can create an electrical field and as electric current flows through a machine or device, it can generate an electromagnetic field. As a rule of thumb, the higher the voltage of the machine, the stronger the field. Electromagnetic fields can also be produced naturally, such as in the air after the build-up of electricity following a thunderstorm. The earth’s North and South Poles also generate an electromagnetic field that can be used by birds for navigation.1 Most of the time, the electromagnetic fields all around us have little effect on us.
However, there are times when the electromagnetic fields generated by certain machines, equipment, and devices can interfere with implantable pacemakers and ICDs. This is called electromagnetic interference (EMI) and it is something pacemaker or ICD patients should know about. The EMI is generated externally, but it may be able travel through your body to reach the pacemaker or ICD, where it can affect how the device operates.
Not all electrical devices create EMI that affects pacemakers or ICDs. However, it is well known that the following devices and equipment create EMI that can be a problem for people with pacemakers and ICDs:2
- Magnetic resonance imaging (MRI) devices in the hospital
- Cardioversion procedures using direct current
- Radiofrequency catheter ablation procedures
- Electrocautery used during surgery and other medical procedures
- Radiation therapy
- Extracorporeal shock-wave lithotripsy
- Arc welding equipment
Some things may or may not create EMI that can affect your device:
- Security systems such as those at the airport
- Anti-theft detection systems used in stores
- Cell phones
- Transcutaneous nerve stimulators
When pacemakers were first invented, it was generally thought that microwave ovens would interfere with these devices. With today’s well-shielded devices and modern microwaves, this is no longer a problem.
It is hard to live modern life without encountering electrical and electromagnetic fields, but if an electromagnetic field interferes with your pacemaker or ICD you are likely to experience symptoms such as feeling dizzy, woozy, light-headed, or unwell. If you move out of range of the electromagnetic field—even just taking a few steps away—may put you out of reach of EMI and cause you to feel better. Even if you do not have symptoms, you should avoid getting close to known sources of EMI.
EMI and Your Device
EMI does not permanently damage your device, but it may cause it to act abnormally. In simple terms, the pacemaker or ICD receives the EMI and mistakes it for cardiac activity and then does not pace the way it normally would. In truth, your heart may not be beating rapidly at all. When you get away from the EMI, the pacemaker or ICD should resume normal activity.
In some cases, the EMI may reset your device. A device reset occurs as a safety precaution. In this case, the pacemaker or ICD recognizes that there is EMI making it hard for the pacemaker or ICD circuits to know what is a cardiac signal and what is noise. The device then “resets” to a safety program to provide you with appropriate pacing support and tune out the outside signals. However, you may need to see your doctor to have the reset mode turned back to normal pacing. This does not damage the device but pacing in the reset mode may not be the most optimal pacing therapy for you.
Sometimes you may know you are in an EMI zone even if you do not feel any symptoms. For example, if you go to the airport and pass through the security checkpoints, it is likely that you are near an electromagnetic field. Even if this does not seem to affect your device, it is best for you to pass through the metal detectors and other security systems as quickly as you reasonably can. You do not need to run through them, but you should not linger under a metal detector, either.
Cell Phones and EMI
Cell phones are usually not problematic for people with pacemakers or ICDs but it is recommended that you hold the phone to the ear on the opposite side of the body from your implant site. If your pacemaker or ICD is implanted on the right side of your chest, hold your phone up to your left ear. Avoid carrying the cell phone in a pocket that would put it in proximity to where your device is implanted.
Other Sources of EMI
Many machines and devices used in medicine can cause EMI. A good practice is to tell all of your doctors, dentists, nurses, chiropractors, clinicians, and other healthcare practitioners that you have a pacemaker or ICD. Remind them, even if you think they know. They will know about potential sources of EMI with medical equipment and what can be done. In some cases, there may be simple steps to take to protect you from EMI.
If you need to undergo an MRI make sure you tell your heart doctor as well as the doctor ordering the image. An MRI has the potential to cause serious damage to the pacemaker or ICD and may even injure you. There are some pacemakers and ICDs that are compatible with an MRI, but this should be discussed in advance because special preparations may be needed.
Have a conversation with your heart doctor about environments that concern you, such as being near high-power lines. Amusement park rides, in particular bumper cars and go-karts, may be a source of EMI. When in doubt, talk to your physician.
1 World Health Organization. What are electromagnetic fields? World Health Organization,. Electromagnetic fields (EMF) Web site. https://www.who.int/peh-emf/about/WhatisEMF/en/. Accessed November 13, 2019.
2 Erdogan O. Electromagnetic interference on pacemakers. Indian pacing and electrophysiology journal. 2002;2(3):74-78.