FAQ

Bioimpedance analysis (BIA) — also known as bioimpedance body composition analysis — is a method of estimating body composition by sending a low-level electrical current through the body. It is commonly used in scales, gym equipment, and clinical settings. Manufacturers have traditionally recommended that patients with pacemakers, ICDs, or cardiac resynchronisation therapy devices (CRT-Ds) avoid BIA due to concerns about potential interference.

However, a small study published in 2012 evaluated 20 patients with heart failure who had either an ICD or CRT-D device implanted. The researchers performed BIA whilst monitoring their devices in real time and found no evidence of interference, including no telemetry disruption, no oversensing on the device leads, and no symptoms experienced by the patients.

Whilst this study suggests BIA may be safe in patients with certain cardiac implants, the researchers noted that further confirmatory studies with larger patient groups are still needed. As always, consult your cardiologist or cardiac electrophysiologist before undergoing any procedure if you have an implanted cardiac device.

If you receive a brief electric shock from UK mains (240v) and have no visible injuries, the risk of damage to your ICD or lead is theoretically present but extremely unlikely and would be classed as very low risk.

This is because the current tends not to pass through the ICD or lead but passes through the body to the ground using the shortest and quickest route — for example, hand, up the arm, down the torso, and out through the leg. The majority of devices also have circuitry built in to protect them against electrical surges.

If you are feeling unwell after the shock, go to hospital. Otherwise, contact your local device clinic and request a device check, which can often be performed as a remote transmission. This will pick up any rare issues and provide reassurance.

Maintain at least the recommended distance between the item and your heart device:

30cm (12 inches) distance

Car or motorcycle – from ignition system components
Electric fence
Electric pet containment fence – from buried wire and indoor antenna
Electrical transformer box

60cm (2 feet) distance

Metal detector – from the search head
Induction hob

Not recommended

Abdominal muscle stimulator (TENS-type ab belt)
Electronic body fat scale
Magnetic mattress pad or pillow

Maintain at least a 15cm (6 inch) distance between the item and your heart device:

Electric golf buggy – from motor
Hand-held electric kitchen appliances (electric whisk, electric knife)
Electric shaver – corded
Electric toothbrush charging base
Exercise bike – from magnet in wheel
Hair dryer – hand-held
Hand-held back massager
Magnetic therapy products
Radio-controlled items – from antenna
Sewing machine – from motor
Small household magnet
Speakers
Tattoo machine
Treadmill – from motor
Ultrasonic pest repeller
Vacuum cleaner – from motor

The electromagnetic energy generated by a chainsaw is similar to other electric and liquid fuel-powered tools. If electromagnetic interference occurs with your heart device and you experience symptoms such as becoming dizzy or lightheaded, a running chainsaw may present a higher risk of injury to you than other power tools.

Yes, but exercise extreme caution at all times. Follow the safety precautions below to minimise the risk of interference with your heart device while using a chainsaw.

• Maintain at least 15cm (6 inches) between the motor of an electric chainsaw and your heart device
• Ensure the equipment is properly earthed
• Maintain at least 30cm (12 inches) between the ignition system components of a petrol chainsaw and your heart device. Where possible, use a model with the spark plug positioned away from the handgrips
• Stop cutting and switch off the chainsaw immediately if you feel lightheaded, dizzy, or believe your ICD has delivered a shock
• Do not work on the engine while it is running
• Do not touch the coil, distributor, or spark plug leads of a running engine

It is recommended you avoid using welding currents above 160 amps. If welding with currents under 160 amps, follow the precautions below to minimise the risk of interference with your heart device.

Welding safety precautions

Limit welding to currents below 160 amps
Work in a dry area wearing dry gloves and footwear
Maintain at least 60cm (2 feet) between the welding arc and your heart device
Keep welding cables close together and as far from your device as possible. Position the welding unit approximately 1.5 metres (5 feet) from the work area
Connect the earth clamp to the metal as close to the point of welding as possible
Wait a few seconds between attempts when having difficulty starting a weld
Ensure firm footing and adequate space to move freely
Work with someone else who is aware of your condition
Stop welding immediately and move away from the area if you feel lightheaded, dizzy, or believe your ICD has delivered a shock

As welding equipment may temporarily affect your heart device, any decision to use welding equipment should be made in consultation with your cardiologist or device clinic. Protective aprons and vests will not shield your device from electromagnetic interference generated by welding equipment.

Unlike most other household power tools, welding with currents above 160 amps may have a higher tendency to temporarily affect the normal function of your pacemaker or implantable defibrillator.

Even though most electromagnetic fields in the home environment will rarely affect the function of a pacemaker or ICD, it is recommended you keep any item containing magnets at least 15cm (6 inches) away from your device.

The reason for this is that there is a small magnetically activated switch built into pacemakers and ICDs. This internal switch is designed to close when a magnet of sufficient strength is placed over it.

When the switch closes in a pacemaker, the device paces the heart at a fixed pre-set rate (which may differ from your programmed settings).

When the switch closes in an ICD, it prevents the device from delivering treatment therapies.

You may not always know whether an item contains a magnet. However, if household items are used as intended and properly maintained, they should have no effect on your heart device. This includes microwaves, kitchen appliances, cordless phones, radios, televisions, computers, hair dryers, electric shavers, electric toothbrushes, electric blankets, and small power tools.

If you accidentally place a magnet too close to your device, simply move the item away. The pacemaker or ICD will return to its normal programmed settings once the magnet is removed.

The use of magnetic mattress pads and pillows is not recommended as it would be difficult to maintain a 15cm (6 inch) separation from your device at all times.

Yes. Anti-theft security systems in shops and libraries generate electromagnetic fields that detect embedded tags on merchandise. Under unusual circumstances, these fields could temporarily affect the operation of your heart device, but significant interference is unlikely if you walk through normally.

It is recommended that you:

Be aware of anti-theft detector gates as you enter and leave
Walk through at a normal pace and do not linger near the equipment
If you experience any symptoms such as dizziness or palpitations near a security system, move away promptly. Your device will resume normal operation once you are clear of the equipment.

Prior to any scan, your doctor should determine whether there is an effect on your heart device.

See our MRI Compatibility page for more information.

Your doctor should discuss all potential benefits and risks of an MRI scan with you. Present your ID card to the doctor recommending the MRI scan. If needed, your doctor can seek more information from the manufacturer of your ICD.

You should speak with your doctor regarding this situation.

Many modern ICDs and leads are compatible with MRI scanners and many are retrospectively approved.

See our MRI Compatibility page for more information.

Many modern devices and leads are now MRI compatible but older ones are often not.

You can get more information about how to check by going to our MRI Compatibility page.

When using a powered hand tool, whether battery-powered or electric, keep the tool’s motor at least 15cm (6 inches) away from your device.

Yes, you can use a heating pad. They have no known effect on ICDs.

In most cases, you can undergo laser hair removal. Check with your doctor and the manufacturer of your ICD.

A transmitting sound amplifier worn around the neck should be kept at least 15cm (6 inches) away from your ICD at all times. If the device hangs at chest level, check that the position does not bring it close to your implant site.

It is possible to have both an ICD and a vagal nerve stimulator. Some precautions may be necessary, however. Consult with your doctor.

Phones, which use wireless signals, have electromagnetic fields around them. Some of these fields may affect the normal operation of your heart device. Your phone should be kept at least 6 inches away from your device.  When using a mobile phone, it is best to hold it to the ear that is farthest away from your heart device. Also, is a good idea to avoid carrying your phone in a shirt pocket that is close to the ICD.

No, your phone should be kept at least 6 inches away from your device. Cell phones, which use wireless signals, have electromagnetic fields around them. Some of these fields may affect the normal operation of your heart device. When using a mobile phone, it is best to hold it to the ear that is farthest away from your heart device.

Wireless battery chargers that don’t require an AC plug-in are used to charge items such as cell phones, music players and tablets. When using this type of charger, keep at least 6 inches between the charger and your ICD.

When using an AC charger of up to 100 amps, such as those used to recharge a car battery, keep your ICD at least 12 inches away from the charger.

For some electric vehicles, there may be safety precautions when charging the battery. For example, you may not be able to sit in the vehicle while it is charging. Check with the car’s manufacturer for guidelines.

Yes, it is safe to drive an electric car if you have an ICD or other heart device.

Cosmic rays consist of high-energy radiation that strikes the earth from space. Most of these flares and rays are absorbed in the atmosphere and are unlikely to affect an ICD once they reach the ground.

If you work on power lines, you may encounter interference with your ICD’s operation. Consult with your employer and your doctor.

Standing under large power lines at ground level should not affect your ICD. However, stay out of any fenced areas such as substations.

Yes. You can work on your car as long as there is no medical reason to avoid working around engines. You should, however, keep at least 12 inches between your ICD and parts of the car’s ignition system.

You should keep at least 12 inches between your ICD and parts of the car’s ignition system.

Using a vibrator poses no risks. Just make sure the vibrator is in good working condition and has no electrical problems.

A momentary shock will not permanently damage your ICD. A memorable (longer) shock may cause some ICD settings to be reset to nominal values. Your doctor can restore your individual settings in the clinic.

Yes. Both mains-powered and battery-powered electric fences pose a low risk to your ICD, because the electrical pulse is delivered very briefly — approximately once per second. If you accidentally touch an electric fence, the momentary shock will be startling but will not permanently damage your device. It may temporarily affect the pacing function of your ICD, but normal operation will resume once you move away.

Keep at least 30cm (12 inches) between your ICD and the fence wire and energiser unit when working near electric fencing.

MRI equipment generates large magnetic fields and radio waves that may interfere with ICD operation. Check with your doctor to see what precautions, if any, you should follow when working around MRI machines.

Items that generate or use electricity or transmit wireless signals have electromagnetic fields around them. Some of these fields may affect ICD operation. Remember that most items used in everyday life are not likely to affect your ICD. However, if you are concerned about equipment in your work environment, ask your employer to measure electric field intensity limits that may interfere with your ICD or to hire an outside firm to do so.

Yes, you can use a urinary monitor that includes a magnet. Just remember to keep the tether magnetic strap and battery compartment of the monitor at least 6 inches away from your ICD.

No. The tiny electrical current produced by a novelty hand buzzer or similar toy is far too weak to interfere with an ICD. There is no clinical evidence that these devices pose any risk to implanted cardiac devices.

If you have any concerns about a specific device or situation, contact your ICD clinic for reassurance.

Pet shock collars for electric pet fences, including remote controls and bases with antennas, should be kept six inches away from your heart device.  Buried wires should be at least 12 inches from your ICD.

Yes. A petrol-powered lawn mower requires you to keep at least 30cm (12 inches) between the running ignition system and your ICD. For electric lawn mowers, maintain at least 15cm (6 inches) between the motor and your device. These are the same precautions as for other petrol and electric powered tools.

E-readers have wireless transmitters to work on data networks, so we recommend keeping them 6 inches away from your ICD. So, no, you shouldn’t fall sleep with them snuggled up close. That’s getting a little too attached to your technology anyway.

Yes, you can use mobile phones. However, mobile phones may cause electrical interference with your heart device when the phone is turned on and held too close to your heart device. Also, some accessories for mobile phones contain magnets that may cause interference, such as earbuds or cases with magnetic clasps. Any effect is temporary, and simply moving the phone or accessory away will return the heart device to its previous state of operation.

Definitely. Just keep them 6 inches away from your ICD.

Get your yard maintenance on. It’s fine to use a powered lawnmower as long as you keep some distance between the running mower and your ICD. For electric motors, stay 6 inches away. If you’re using a gas-powered mower, keep the ignition (spark plug area) at least a foot away from your heart device.

Always carry your heart device ID card. This card is helpful if your heart device sets off a metal detector or a security system.

Yes. Using a microwave won’t affect your ICD.

Don’t be all pins and needles about this one. Acupuncture is no problem, as long as it’s not acupuncture with an electrical stimulus. Electrical stimulus could be detected by your ICD, potentially resulting in an inappropriate shock.

Yes. Gas powered snow blowers can be used. It is recommended that you keep at least 12 inches between the running motor and the ICD.

Yes, you can. But keep it at least a foot away from your chest, which you’d probably do anyway.

Yes, you can stay toasty under your electric blanket without harming your ICD.