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Thursday, 18 May, 2000, 12:03 GMT 13:03 UK
Magnet mattresses 'could switch off pacemakers'
Pacemakers could be affected
Mattresses containing magnets, sold as a remedy to arthritis and back pain, could interfere with pacemakers, says a doctor.

Dr Thomas Mattioni, of the Arizona Heart Institute in Phoenix, said that should a powerful magnet be placed too close to the heart, it could temporarily switch off the device.

Anything that has a magnetic field, including these mattresses, should be considered carefully

British Heart Foundation
Magnets could also interfere with the workings of implantable heart defibrillators, he said.

Magnet therapy is growing in popularity, with strap-on magnets available for aches and pains in various parts of the body.

It is believed that the magnets may improve blood flow, although many doctors are sceptical.

However, it is those magnets placed within a few inches of the heart that concern Dr Mattioni.

One inch warning

He conducted experiments on a variety of commercially-bought mattress pads, and while most were weaker than claimed in literature, they were still able to interfere with the pacemaker when the magnet was placed less than one inch from the skin on the chest.

He advises that "therapeutic magnets" should be kept at least six inches away from the chest to be on the safe side.

Thousands of Britons have pacemakers, which regulate the heartbeat in people who have abnormal heart rhythms.

If the pacemaker is halted, and the patient suffers an abnormal rhythm, there is a potential danger.

A spokesman for the British Heart Foundation said: ""Pacemakers are manufactured to the very highest standards and problems with them are rare.

"They are fairly resistant to outside interference - however close proximity to powerful electromagnetic signals or metal detectors could affect the sensing mechanism of some pacemakers.

'Treat with caution'

"Patients are advised to walk past and not linger near them. Anything that has a magnetic field, including these mattresses, should be considered carefully and treated with caution by people with pacemakers fitted.

"Patients should not be unduly anxious but should raise any concerns they have with their pacemaker clinic."

Last year other scientists warned that security scanning devices placed in shop doorways - which produce an electromagnetic field - could also be dangerous to those with implantable defibrillators.

The field can trick the device into thinking the patient's heart has stopped, and start delivering electric shocks to get it started again.

At least one case in which this happened was quoted by the scientists, and shops were asked to make sure any scanners were accompanied by clearly visible warning signs.

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02 Apr 99 | Health
Baby fitted with pacemaker
06 Apr 00 | Health
40 years of the heart pacemaker
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