The Heart Beat

Photo Credit: Bruno Pedro

A high school student with a desire to pursue a medical career has produced an interesting study in which it was determined that when an iPod is placed in close proximity to a pacemaker, it can cause the pacemaker to malfunction.

It has long been known that electrical devices, such as microwave ovens, cell phones, and other electronic appliances, can cause pacemaker malfunction. Medical providers typically recommend to pacemaker patients that they not place hand held electronic devices directly over the pacemaker, and that they not stand within 2-3 inches of appliances such as a microwave oven.

Jay Thaker, a Michigan high school student reported that his study involved holding an iPod within two inches of a the pacemaker in 83 patients for a range of 5-10 seconds. His results indicated that “telemetry interference” occurred in 29% of the study participants, and “over sensing” occurred in another 20% of the patients.

Telemetry interference could cause a pacemaker to record what appears to be an abnormal heart rhythm when one doesn’t really exist. This is important because the history of heart rhythm disturbances is stored in the pacemaker for the medical provider to read at some future date; this interference could cause the provider to treat an abnormal rhythm that didn’t really occur, but seemed to be present on the recorded data.

Over sensing is a situation in which the pacemaker thinks that it sees a rhythm problem that it should respond to and does so, even though that rhythm doesn’t exist. For example, it might think that the person’s heart rate is rising because of exertion, and if it has a rate smoothing function it would make an incremental adjustment in heart rate, increasing the heart’s pace. This could be disconcerting if the person was lying down to sleep for the night with a good book in the iPod. In a more serious situation, a combination pacemaker-defibrillator might think that it was seeing a rhythm thst should be shocked; this could cause an inappropriate shock to be delivered to the heart. At best this is an unplesant surprize; at worst it would send the heart into electrical chaos.

In one patient from this study the iPod caused the pacemaker to stop altogether. In a person who is dependant on their pacemaker to maintain a heart beat at all, device failure would result in the heart stopping, known as cardiac arrest.

Student Thacker recognizes that the typical iPod user doesn’t also have a pacemaker, but wants them to be aware of the risk, because iPods may be commonly used around them. His study will be published in association with doctors from Michigan State University and the University of Michigan, and was expected to be presented to the Heart Rhythm Society’s annual meeting, in Denver on May 10th, 2007.

Take care, Laurie

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• WebMD Video: Surgery for Heart Rhythm Disorder Improved

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