I’ve reported here before how the magnets in your headphones or ear phones can interfere with your cardiac implants such as a pacemaker or an implantable cardioverter-defibrillators (ICD). Portable headphones of MP3 players, mobile phones, and iPods usually contain neodymium magnets to create vibrations and sound waves. The magnetic field can cause interference when worn close to the implants.
A group of scientists at the Beth Israel Deaconess Medical Center decided to look deeper in the issue. They evaluated the magnetic field strength of portable headphones and investigated whether they can cause clinically relevant magnetic interference. Specifically, they looked at effects of different types of portable headphones on 100 patients with implants.
The researchers looked at the 8 most commonly used models of headphones, two which are clip on headphones (over the ears) and 6 ear phones (aka ear buds or inside the ears).
The models evaluated were:
- Sony MDR-Q22LP clip-on
- Phillips SBC HS430 clip-on
- Phillips SHE5920 in-ear
- Bose in-ear
- Sony MDR-E828LP in-ear
- JVC HA-F130A in-ear
- Apple in-ear
- JVC HA-FX33A in-ear
The electromagnetic fields of the 8 models were measured with a Gauss meter. The results showed:
- All eight models tested exceeded 10 Gauss, an electromagnetic field strong enough to close the read switch and disable sensing in the implanted cardiac device.
- Five out of the 8 models had levels over 200 Gauss.
- The strengths were the same whether the phones were plugged into the music player or not or whether the music player was running or not.
- 30 patients with implants experienced interference when certain models were placed within 2 cm or less from the skin surface of the chest.
- Problems included a disruption in the detection of tachyarrhythmia in cardioverter-defibrillators and asynchronous pacing in pacemakers.
- Removal of the phones from the patient’s chest immediately restored device function in all except one of the 30 cases of magnetic interference. In this one case, the implant was permanently reprogrammed.
- Magnetic interference was not observed when phones were placed at a distance of 3 cm or more from the skin surface.
The model with the highest strength at 0 cm (directly on the skin) was Sony MDR-Q22LP clip-on which measure 344 Gauss. However, distance seems to matter. As the sound devices were moved away from the implant, the strength of the electromagnetic field decreased below 10 Gauss, at least with the ear bud models but not with the two clip-on versions, which remained above 10 Gauss at 2 cm. At 3 cm, all models have strengths below 10 Gauss.
The model that produced the least amount of magnetic field strength was the JVC HA-FX33A in-ear model at 11 Gauss when placed directly over the meter.
The study concluded:
Clinically significant magnetic interference can occur when portable headphones are placed in close proximity to implanted PMs and ICDs. Patients with such a device should be advised to keep portable headphones at least 3 cm from their device.
With these study results, consumers can judge better which models of headphones can pose a risk for those with heart implants.