How to Turn Off a Pacemaker With a Magnet After Death

A magnet placed over a pacemaker does not actually turn it off. It switches the device to a fixed-rate pacing mode, meaning the pacemaker fires at a steady rate regardless of what the heart is doing. After death, the heart cannot respond to those electrical signals anyway, so the distinction is somewhat academic for a pacemaker alone. The situation is quite different for an implantable cardioverter-defibrillator, or ICD, where a magnet suspends the shock function and genuinely matters for the comfort and safety of everyone nearby. Understanding what magnets can and cannot do to these devices, and why the answer varies by manufacturer and device type, turns out to be more involved than most people expect.

What a Magnet Actually Does Inside the Device

Pacemakers and ICDs contain a tiny component called a reed switch, which is essentially two thin metal strips sealed inside a glass tube. When you hold a sufficiently strong magnet over the device, the magnetic field pulls those strips together, closing the switch. That change in the circuit tells the pulse generator to shift into a pre-programmed response mode.¹ For a standard pacemaker, this means the device stops listening to the heart’s own rhythm and begins pacing at a fixed rate, typically somewhere between 65 and 100 beats per minute depending on the manufacturer and how much battery life remains.² The device is still producing electrical impulses. It has not been shut down. It has simply been switched from “demand” mode, where it only fires when it detects the heart needs help, to “asynchronous” mode, where it fires continuously at a set pace.

After someone has died, a pacemaker in asynchronous mode is still sending tiny electrical pulses into tissue that will never contract again. In a living patient, this asynchronous mode carries its own risks because the device can fire at the wrong moment during the heart’s natural cycle. After death, those risks are irrelevant. The pacemaker will eventually stop on its own when its battery runs out, which could take months or even years. For most post-mortem purposes, the pacemaker itself is not the urgent concern. The ICD is.

Why ICDs Are the Real Post-Mortem Concern

A pacemaker gives gentle electrical nudges to keep the heart beating at the right rhythm. An ICD does that too, but it also monitors for dangerous fast rhythms and delivers powerful shocks to reset them. Those shocks are strong enough to jolt the body visibly. After death, the heart’s electrical activity becomes chaotic and disorganized before stopping entirely, and an ICD can interpret that chaos as a life-threatening arrhythmia. The device may then start delivering shocks to a person who has already died.

This is not just an abstract problem. Studies have documented that shocks from ICDs during the dying process are painful and distressing for patients who are still conscious, and deeply upsetting for family members and caregivers who witness them.³ A family member holding the hand of someone who has just passed away does not expect to feel a strong electrical jolt. Anyone touching the body when the ICD fires can feel the shock. For hospice workers, funeral home staff, and family providing end-of-life care, this is a real and sometimes traumatic safety issue.

When a magnet is placed over an ICD, it suspends the tachyarrhythmia detection function, which means the device stops monitoring for fast rhythms and will not deliver shocks.⁴ The pacing function of the ICD typically continues, but the shocking function, the part that matters most after death, is disabled for as long as the magnet remains in place. Remove the magnet and the ICD begins sensing again and may resume delivering shocks.⁵ This is why, in hospice settings, families are often given a clinical magnet and instructed to tape it over the device if the patient begins receiving repeated shocks near the end of life.

Getting the Magnet in the Right Place

Not just any magnet will work. The magnetic field needs to be strong enough and close enough to activate the reed switch. A field of at least 10 gauss aligned with the switch is required, and the magnet typically needs to be placed directly over the center of the device, which usually sits beneath the skin just below the collarbone on either side of the chest.⁶ Clinical-grade ring magnets or donut magnets designed for this purpose are the standard tool. In patients with more body tissue over the device, two magnets stacked together may be needed to generate a strong enough field.

One manufacturer-specific wrinkle worth knowing: most devices respond to a magnet placed over the center of the generator, but certain older St. Jude (now Abbott) ICDs require the magnet to be positioned over the poles of the device rather than the center.⁶ Placing it in the wrong spot may produce no response at all. Small neodymium magnets, the kind found in consumer products, can interfere with devices at distances of up to about 3 centimeters, but their small size makes them unreliable for intentional clinical use.⁷ A proper clinical magnet is inexpensive and widely available, and it is the right tool for this job.

Manufacturer Differences That Can Surprise You

Here is where things get complicated, and where the simple “place a magnet and you’re done” narrative breaks down. Different manufacturers program their devices to respond to magnets in different ways, and some devices can be programmed to ignore magnets entirely.

Medtronic pacemakers do not have a magnet “off” mode, meaning a magnet will always trigger asynchronous pacing. Boston Scientific pacemakers typically switch to asynchronous mode, but they can be programmed to a magnet “off” setting in which the device simply ignores the magnetic field. St. Jude Medical (Abbott) devices offer multiple programmable magnet modes, including a mode that stores an ECG recording but does not change pacing at all. Biotronik devices have their own set of responses, including a synchronous mode that maintains the programmed pacing rate without switching to asynchronous pacing.⁸

The variability across manufacturers means you cannot assume that every device will respond predictably to a magnet.⁹ In a clinical setting, the device can be reprogrammed using the manufacturer’s dedicated programmer, which communicates wirelessly with the implanted generator. That reprogramming can permanently disable the shock function of an ICD or turn off pacing entirely. A magnet is a temporary workaround, not a permanent solution. For post-mortem purposes, however, permanent reprogramming is rarely necessary because the device will be removed before cremation or burial in many cases anyway.

Why the Device Needs to Come Out Before Cremation

The most pressing practical reason to deal with a pacemaker or ICD after death has nothing to do with the magnet question at all. It is about cremation safety. Pacemakers and ICDs contain sealed lithium batteries and, in the case of ICDs, high-voltage capacitors. When exposed to the extreme heat of a cremation furnace, these components can explode violently.

A UK survey found that roughly half of all crematoria had experienced at least one pacemaker explosion, and that these events could cause structural damage to the cremation chamber and pose injury risks to staff.¹⁰ Experimental testing in Japan confirmed that all cardiac devices tested exploded during cremation, with average times from ignition to explosion of about four to five minutes depending on furnace temperature.¹¹ A separate study found that the explosions produced sound levels above 120 decibels and damaged brick structures, while also releasing small quantities of benzene and hydrogen fluoride, though at levels within occupational exposure limits for a cremation chamber environment.¹²

Because of these risks, cremation forms in many countries specifically ask whether the deceased has an implanted cardiac device and whether it has been removed. Funeral homes and crematoria routinely explant these devices before proceeding. A survey of morticians found that each one removed an average of about seven devices per year, with the most common disposal method being placement in medical waste, though roughly one in five devices was donated for potential reuse in developing countries.¹³

One interesting exception: leadless pacemakers, which are tiny capsule-shaped devices implanted directly inside the heart rather than under the skin of the chest, appear not to pose the same explosion risk. A small case series of patients cremated with a Medtronic Micra leadless pacemaker in place reported no explosions and no damage to the cremation chamber.¹⁴ The much smaller battery in these devices likely explains why, though the evidence base is still thin.

The Legal and Ethical Landscape

Families sometimes worry that deactivating an ICD or requesting the disabling of a pacemaker is morally or legally equivalent to euthanasia. The medical and legal consensus is clear on this point: patients with decision-making capacity have the right to request withdrawal of any life-sustaining therapy, and honoring that request is neither euthanasia nor physician-assisted suicide. There is no meaningful legal or ethical distinction between withdrawing mechanical ventilation, stopping dialysis, removing a feeding tube, or deactivating a cardiac device.¹⁵

After death, these ethical questions largely evaporate. The device is functioning in a body that no longer needs it. The decision to disable it via magnet or to remove it physically is a practical matter, not a moral one. Still, some families find the conversation difficult, especially if it was not discussed before the patient died. Hospice and palliative care teams increasingly try to address device management as part of advance care planning so that families are not confronting these decisions in the immediate aftermath of a death.

Forensic Value Before You Remove Anything

Before a pacemaker or ICD is removed from a deceased person, there is an often-overlooked reason to interrogate it first. These devices continuously record cardiac rhythm data, therapy delivery logs, and other diagnostic information that can be medically and forensically valuable. A study of post-mortem device interrogation found that in cases where the forensic autopsy alone could not determine the time of death, interrogating the implanted device helped establish it in 70% of those cases. Where the cause of death was uncertain, device data clarified it in about 61% of cases.¹⁶ A separate investigation found that interrogation revealed potentially lethal heart rhythm disturbances in 9 out of 70 patients investigated post-mortem and enabled reasonable estimation of the day of death in 15 patients.¹⁷

This matters because once the device is removed and discarded, that data is gone. In cases involving unexpected death, questions about inheritance or insurance, or any legal proceedings, the stored rhythm data can be decisive evidence. Forensic pathologists and medical examiners are increasingly recognizing that post-mortem device interrogation should be routine rather than an afterthought. If you are in a position where a family member has died with an implanted cardiac device and the death is being investigated or was unexpected, it is worth asking whether the device has been interrogated before it is removed.

What Happens to Explanted Devices

Most devices removed after death end up in medical waste. But a substantial minority have enough battery life remaining to be useful to patients in countries where new devices are unaffordable. A large device reutilization program that collected generators from funeral homes and crematoria found that about 21% of donated devices still had adequate battery life for potential reuse. Among the more complex biventricular ICDs, that figure was closer to 30%.¹⁸ With proper sterilization and quality control, these refurbished devices can serve patients in low- and middle-income countries who would otherwise have no access to cardiac rhythm management.¹⁹

Despite this potential, the survey of morticians found that only about 4% had ever returned a device to a manufacturer, though the vast majority said routine explantation and return would be feasible if a system existed.¹³ The infrastructure gap between devices being removed and devices reaching patients who need them remains a significant missed opportunity.

Smartphones and Accidental Magnet Mode

A side note worth mentioning for anyone living with a pacemaker or ICD, or caring for someone who does: the magnets in modern smartphones are strong enough to activate the reed switch in some cardiac devices. Testing found that an Apple iPhone 14 induced magnet mode in 44% of the cardiac devices tested, including all tested standard pacemakers and certain Medtronic ICDs. In contrast, a Google Pixel 8 Pro did not trigger magnet mode in any device tested. A thin steel plate placed on the back of the iPhone successfully shielded against the magnetic interaction in every case.²⁰

The practical takeaway is straightforward: keep smartphones at least six inches from an implanted cardiac device. Do not rest a phone on the chest near the device site, and do not carry it in a breast pocket on the same side as the implant. This applies to living patients, not to the post-mortem situation, but it illustrates how sensitive these reed switches can be to magnetic fields and why a dedicated clinical magnet works so reliably when you need it to.