A pacemaker is a small, implanted medical device designed to help regulate an irregular or slow heart rhythm. It generates low-energy electrical pulses that ensure the heart beats at a consistent and healthy rate. Certain magnetic fields can temporarily influence how a pacemaker functions.
How Pacemakers Interact with Magnetic Fields
Pacemakers are designed with a feature that allows them to respond to external magnetic fields. This is facilitated by a magnetic reed switch or, in newer devices, a Hall effect sensor. When a sufficiently strong magnetic field is applied near the device, it can cause this internal switch to close.
The closure of the reed switch typically prompts the pacemaker to enter a “magnet mode,” where it temporarily switches to a fixed-rate pacing. It delivers electrical impulses at a predetermined, steady rate, regardless of the heart’s natural electrical activity. This effect is temporary and reversible; once the magnetic field is removed, the pacemaker usually returns to its normal function. While this response is often a built-in safety feature used in clinical settings, unexpected activation by external magnets can be a concern.
Which Small Magnets Pose a Risk
The potential for a small magnet to affect a pacemaker depends primarily on two factors: the magnet’s field strength and its proximity to the implanted device. Not all “small” magnets are equally problematic. Very weak magnets, such as typical refrigerator magnets, generally do not pose a risk at a safe distance.
However, stronger rare-earth magnets, like neodymium magnets, are often found in many modern consumer electronics and can interfere with pacemaker function. These magnets can generate magnetic fields strong enough to activate the pacemaker’s magnet mode if brought too close. Fields stronger than about 10 gauss can potentially alter device function.
Common Household Items with Magnets
Many everyday household items contain magnets that could potentially affect pacemakers if held too close. Smartphones have internal magnets for wireless charging and accessories. Smartwatches incorporate magnets in their charging mechanisms and bands.
Headphones and earbuds with magnetic charging cases or strong drivers can pose a risk. E-cigarettes with magnetic components for attaching pods or charging, and small speakers, should be kept at a safe distance. For all these items, maintain the recommended separation from the pacemaker to avoid unintended interference.
Practical Safety Guidelines
For individuals with pacemakers, it is advisable to maintain a safe distance between the device and any items containing magnets. Keeping magnetic devices at least 6 inches (approximately 15 centimeters) away from the pacemaker is a good general practice. Avoid placing items with magnets, such as cell phones or tablets, in shirt pockets or directly over the area where the pacemaker is implanted.
When using a cell phone, hold it to the ear opposite the side of your body where the pacemaker is located. If you experience any symptoms like dizziness, lightheadedness, or heart palpitations when near a magnetic item, move away from the source immediately and contact your doctor or cardiologist. Always inform medical professionals about your pacemaker before any procedures that might involve strong magnetic fields.