by

Charles A. Bertrand, M.D., FACP, DIM-CD (Ret.)
Associate Clinical Professor of Medicine at New York Medical College
and at the Medical University of South Carolina

INTERFERENCE WITH CARDIAC PACEMAKERS BY CELLULAR TELEPHONES

There are many patients in the United States who have cardiac pacemakers and the question has arisen as to the degree of interference, if any, with pacemaker function by the use of cellular telephones. Hence, a group of hospitals combined to answer the question. This study was a multi-centered trial coming from the Mayo Clinic, New England Medical Center, and the University of Oklahoma Health Sciences Center. It was published in The New England Journal of Medicine, Vol. 336, No. 21, pp. 1473-1479 (May 22, 1997) with a companion editorial as well.

A growing body of evidence suggests that electromagnetic interference can occur between pacemakers and hand-held cellular telephones that may pose a public health problem. As a result, this multi-centered prospective trial was a cross-over study including 980 patients who had cardiac pacemakers. These pacemakers were tested against five types of cellular telephones (one analogue and four digital) in order to assess the potential for interference in pacemaker function by cellular telephones. During the time these studies were done the patients had continuous electrocardiography performed to see if there were any changes in the rhythm of the heart. The cellular telephones were tested at different sites, such as in the ear, and in a series of other locations including placement of the 'phone directly over the pacemaker.

A total of 5,533 tests were performed and the electrical interference was approximately twenty percent and the incidence of patient symptoms about seven percent. However, there was no clinically significant interference when the telephone was placed in the usual position over the ear. The most commonly reported symptom was palpitation due to an irregularity of the heartbeat. Lightheadedness and dizziness were also reported, but only in 1.2 percent. No patient passed out, however. The highest incidence of interference occurred when the cellular telephone was placed directly over the pacemaker. The most interesting (and relevant) finding is that cellular telephones had no effect on pacemaker function if they were farther away from the pacemaker generator than four inches. It was also found that analogue telephones appeared to be safer and had even less interference with pacemaker function.

If one has a cardiac pacemaker, then he or she is well advised to keep the cellular telephone away from the pacemaker site by at least four inches. Some recommend, as in the companion editorial, that the ear opposite to the site of the pacemaker should be used when talking on the telephone. This may or may not be necessary since even using the ear on the same side of the pacemaker generator would be farther away than four inches. If any symptoms occur in the pacemaker patient when using a cellular telephone, then that individual should be promptly tested by a cardiologist. It also seems likely that, in the future, there will be appropriate filters or other barriers incorporated in pacemakers to prevent any interference from digital cellular telephones. But, for the present, if one is wearing a shirt, then the patient is well advised not to put the cellular telephone in the breast pocket on the same side as the pacemaker.

The advice provided on this website is intended to be general in nature and should not be relied upon for specific treatment. If you need personal medical attention please contact your physician.

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