Heart & Pacemakers

My 94-year-old neighbour bought a massage chair. Could the magnetic field of this chair disrupt the smooth functioning of his pacemaker?

The possible disturbances depend on the field strength near the chair in functioning and the type of pacemaker. Your question is in the field of electromagnetic compatibility between appliances.

Generally, new pacemakers are less sensitive to these problems of electromagnetic compatibility. However, if the chair is not certified by European standards, it is advisable to perform field measurements to ensure the absence of risk of pacemaker malfunctioning.

From a practical standpoint, we suggest you to consult the supplier / manufacturer of the chair to have information on field values, and to ask the cardiologist for the type of pacemaker implanted. The supplier / manufacturer of the pacemaker (via the cardiologist) will then be able to forward all needed information.

Should workers with pacemakers be careful and avoid working in the vicinity of high voltage powerlines and transformers?

First of all, it’s a question of specifying that the limit values of present directives/recommendations (EU, ICNIRP, ACGIH) do not take account people with pacemakers.

Technically, you need to know that pacemakers in a bipolar mode are a lot less sensitive to fields that the ones in a unipolar mode (adjustment of sensitivity threshold also plays a part). Unipolar pacemakers could be disrupted by electric field intensities lower than the ones recommended by directives and recommendations, sometimes 2kV/m. People with this kind of pacemaker should avoid being in an area where electric fields exceed 1.5 kV/m to have a sufficient safety margin.

In some places, the electric field around high voltage powerlines can exceed 1.5kV/m. However, keep in mind that field intensity varies with line configuration, voltage and the distance from the line.

Concerning magnetic fields, bipolar pacemakers with threshold sensitivity greater than or equal to 2mV, no interference has been detected under 100 microTesla. In the study of Souques et al (2004), more or less 3% of pacemakers were transitory disrupted by magnetic fields, but never under 45 microTesla. This value can be considered as the possible perturbation threshold for a unipolar pacemaker (in one room or in both). Practically, maximal level of magnetic field under a high voltage powerline (measured with respect of legal safety distances) are always below 50 microTesla

To summarize the situation, according to Souques et al (2004),

“Avec les pacemakers actuels, réglés en mode bipolaire avec une sensibilité ventriculaire courante (2mV en général), le risque d’interférence est quasi inexistant pour les expositions rencontrées couramment. Les pacemakers réglés en mode unipolaire ou avec une sensibilité importante sont plus sujets aux interférences. [.] Il est recommandé de ne pas utiliser de petits moteurs (type appareil de bricolage, perceuse…) à proximité immédiate du boîtier du pacemaker.”

(“With actual pacemakers, in a bipolar mode with a current ventricular sensitivity (generally 2mV), interference risk is almost impossible for usual exposures. Pacemakers in a unipolar mode or with a high sensitivity are more subject to interference. […] The use of devices with tiny motors (e.g. DIY devices, drills and so on) are not recommended close to pacemakers.”)

Unipolar pacemakers are increasingly less used in new implantations. However, on the other hand, it happens that pacemakers are changed, when the batteries are weak, without changing the probes placed in the past. Practically, until now, nobody has reported a mishap or incident caused by walking under a high voltage powerline. It should be more dangerous to stand a while under the line, if the person has an unipolar pacemaker with high sensitivity (<2mV).

Let us add that pacemaker disruptions are not as dangerous as we might imagine because the apparatus quickly restores its own rhythm. In most cases, the person fitted with the pacemaker is not conscious of such a disruption.

We advise you to ask your heart specialist which kind of pacemaker is implanted, its programming, and its immunity level to electric and magnetic fields. With these details, an occupational physician will be able to inform workers on the subject.

Some publications:

  • Souques M, Magne I, Lambrozo J. Implantable cardioverter defibrillator and 50-Hz electric and magnetic fields exposure in the workplace. Int Arch Occup Environ Health, 2011 Jan;84(1):1-6 (pdf).
  • Souques M, Magne I, Trigano, A., Franck, R., Héro, M., Nadi, M., Audran, F., & Lambrozo J. Implants cardiaques et exposition aux champs électromagnétiques 50 Hz en environnement professionnel. Archives des Maladies Professionnelles et de l’Environnement, 2008, 69:547-552. (pdf).
  • Hocking B., & Hansson Mild K. Guidance Note: Risk Management of Workers
    With Medical Electronic Devices and Metallic Implants in Electromagnetic Fields. International Journal of Occupational Safety and Ergonomics (JOSE), 2008, Vol. 14, No. 2, 217–222. (pdf)
  • Souques, M. Influence des champs électromagnétiques non ionisants sur les dispositifs cardiaques médicaux implantables. La Presse médicale, 2004 Dec 18; 33(22):1611-5.

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