Advisory

2003-23
April 28, 2003
For immediate release

Health Canada is advising Canadians of a dangerous interaction between diathermy therapy and implanted metallic leads

OTTAWA - Health Canada is advising Canadians of important safety information regarding the interaction between diathermy ("deep heat") therapy and implanted metallic (electrical) leads or implanted medical devices with leads, such as deep brain stimulators, cardiac pacemakers and defibrillators.

There have been two cases reported in the United States where the patient received shortwave diathermy in the vicinity of their implanted deep brain stimulation system. In both cases, the heat from the therapy caused severe and permanent brain damage around the implanted lead electrodes of the medical device.

Individuals with an implanted lead or an implanted system, or who have previously had an implanted lead or system should tell their health professional before receiving any type of diathermy treatment.

Diathermy treatments are used by a variety of health professionals, including physical therapists, nurses, chiropractors, dentists, and sports therapists. Health professionals may refer to diathermy using the term "deep heat".

Diathermy treatments are usually used for the following purposes:

• to relieve pain, stiffness and muscle spasm
• reduce joint contracture
• reduce swelling and pain after surgery
• promote wound healing.

This advisory applies to different types of diathermy therapy, including short wave (radio frequency) diathermy, microwave diathermy, and, under certain conditions, ultrasound diathermy.

The energy from shortwave or microwave diathermy can cause permanent injury to patients with implanted metallic leads, even if the diathermy is set at levels that do not cause deep heating. Interaction of the energy released by the diathermy device with the implanted lead may cause excessive heating in the surrounding tissue, resulting in serious injury and death.

Ultrasound diathermy may also be dangerous, but only when the ultrasound is applied directly over or near the implant or its leads.

This interaction can occur even if the lead is not connected to any medical device, or even if an implanted medical device is turned off. Patients are still at risk even if only a small portion of the implanted lead or electrode remains in the body.

Diathermy therapy can also cause damage to some implanted systems that contain metallic leads, causing them to malfunction. Examples of implanted systems that may contain a lead include cardiac pacemakers and defibrillators, cochlear implants, bone growth stimulators, deep brain stimulators, spinal cord stimulators, and other nerve stimulators.

If you have an implanted lead or an implanted system, or have previously had an implantead lead or system, tell your health professional before receiving any type of diathermy treatment. If you have any questions or concerns regarding this advisory, Health Canada encourages you to consult with your health professional.

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Media Inquiries:
Emmanuel Chabot
Health Canada
(613) 957-1803

Public Inquiries:
(613) 957-2991