Wearing a smartwatch with a pacemaker is possible, but it requires strict adherence to safety precautions and consultation with a cardiac specialist. A pacemaker is a small, implanted device that uses electrical pulses to regulate the heart rhythm. While modern pacemakers are built with shielding to resist most common electronic interference, certain features of smartwatches can still pose a risk to their function. Users must discuss their specific device and intended smartwatch model with their cardiologist to determine a safe approach.
Understanding Electromagnetic Interference from Smartwatches
Electromagnetic interference (EMI) is emitted by the smartwatch’s wireless communication systems, which operate in the radiofrequency (RF) spectrum. Smartwatches constantly transmit low-power signals for Bluetooth, Wi-Fi, and, in some models, cellular connectivity. These signals can sometimes be interpreted by the pacemaker’s sensitive circuitry as a natural heart signal, a phenomenon known as oversensing.
When a pacemaker oversenses an external signal, it may mistakenly believe the heart is beating normally and temporarily stop sending its own electrical pulses. This inhibition of pacing can lead to symptoms like dizziness or fainting in patients who rely heavily on their device. Smartwatches also use bioimpedance sensors to measure body composition or stress levels by sending a minute electrical current across the skin. This specific electrical current can generate interference that potentially confuses the implanted device. Newer pacemaker models are designed with better filtering capabilities to reject these non-cardiac signals. However, avoiding the use of bioimpedance features in proximity to the chest is a common recommendation to mitigate this electronic confusion.
The Specific Risk of Smartwatch Magnets
A significant threat comes from the powerful static magnetic fields found in smartwatches, particularly in wireless charging coils and magnetic watch bands. Pacemakers contain a specialized component, historically a reed switch, which is intentionally designed to react to external magnetic fields. This feature allows physicians to temporarily program the device into a “magnet mode” during certain medical procedures.
When a magnet with a field strength greater than approximately 10 Gauss (G) is placed near the pacemaker, it triggers this internal switch to close. The closure forces the pacemaker into a fixed-rate, asynchronous pacing mode (VOO, DOO, or AOO). In this asynchronous state, the device delivers pulses at a preset rate without regard for the heart’s natural rhythm. The danger arises if the patient’s own heart rhythm competes with the fixed-rate pacing, which could potentially trigger an arrhythmia. While simply removing the magnet allows the device to instantly revert to its normal sensing mode, the brief period of asynchronous pacing poses a risk. This magnetic activation is relevant when a user places the watch directly over the chest or uses a magnetic charging cable near the implantation site.
Essential Safety Guidelines for Pacemaker Users
To safely use a smartwatch, maintain substantial physical separation between the device and the pacemaker generator. Manufacturers recommend keeping the smartwatch and any associated magnetic accessories a minimum of six inches (about 15 centimeters) away from the implanted device at all times. This distance is effective in reducing both electromagnetic and magnetic field exposure.
Pacemaker users should wear the smartwatch exclusively on the wrist opposite the side of their implantation. Avoid carrying the watch or its magnetic charging cable in a shirt pocket or resting it on the chest. Patients are advised to disable or avoid using features that rely on bioimpedance sensing. If the smartwatch has cellular connectivity, turning off the cellular or NFC functions when they are not actively needed can minimize radiofrequency interference. Patients must consult with their electrophysiologist or cardiologist before purchasing or using a smartwatch.