22 April, 2010
The Effects of Hearing Aids on a Cardiac Pacemaker
How Does a Pacemaker Work?
If you have had a cardiac pacemaker installed, it is possible that you may also wear a hearing aid, especially if you are elderly. Since both of these devices operate electronically, and a hearing aid is operated by a wireless battery that is often kept, for convenience, in a breast pocket near where a pacemaker is most likely installed, there is some concern about whether your hearing aid battery might affect the function of your pacemaker.
A pacemaker monitors and helps control your heartbeat by means of a battery, a computerized generator and wires with electrodes or sensors at one end. The generator is powered by the battery, and both are encased in a thin metal box. The wires, at the end of the box, connect the generator to your heart. The pacemaker works by electricity, detecting the electrical activity of your heart and then, if your heart beats abnormally, sending electrical impulses to shock your heartbeat back to normal. It also records the ongoing electrical activity of your heart, so your doctor can monitor both your heart and the pacemaker.
How Does a Hearing Aid Work?
A hearing aid is a small electronic device that helps to amplify sound. Every electronic hearing aid has a receiver, an amplifier, a battery and electronic circuitry. Most use a remote control device (RCD) to power the hearing aid. There are at least four distinct types of remote control hearing aid devices: FM, electromagnetic induction, tones and infrared to generate a signal.
Hearing Aids and Pacemakers
The question is whether the electrically powered RCD battery of your hearing aid might cause any interference with, or even completely disrupt, your electrically powered pacemaker. This is of concern, since pacemaker function has been known to react negatively to signals from cell phones, electronic surveillance equipment and other wireless technology.
Some product literature for hearing aid RCDs carry warnings that say if you have a pacemaker, you should not keep the remote control for your hearing aid near where your pacemaker was surgically installed. A good example of where not to carry your RCD, according to the literature, would be a breast pocket in a shirt or a suit.
The April 2001 edition of the Hearing Journal carried an article by Levi A. Reiter and Jorge Camunas on "Hearing Aid Remote Control Devices and the Pacemaker Patient." In the article, the authors described two studies they had done on hearing aid devices and pacemakers. The first was a study on a single patient at a pacemaker center, with his physician present. The second was an exploration of the effects of several types of RCDs on several varieties of pacemaker, done within an artificial chest cavity. The authors noted that no published studies or research existed at the time of the article on whether pacemaker/hearing aid proximity might create electronic interference that could adversely affect the pacemaker. Four hearing-aid RCDs were chosen for the second study and operated in four different positions: directly over the pacemaker site, over the site but about 18 inches away, one inch away from the atrial lead wire and one inch from the ventricular lead wire. None of the remote control devices tested in either study interfered with the pacing of the heart or the sensing function of the pacemakers in operation, and there was no stoppage or interference with the regularity of pacing with any RCD used. There was some loss of remote sensing and measuring of heart data (which your doctor would use to check your heart and the working of the pacemaker), at the one inch distance from the pacemaker with the FM and the electromagnetic induction models. The authors of article concluded that no function of the pacemaker was interfered with by normal operation of any of the RCD devices that were tested in any proximity to the pacemaker. But since remote sensing was affected by FM and electromagnetic induction models, product literature warnings should still be observed as to proximity.
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