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【medical-news】iPod：又一个起搏器干扰源？
The iPod: Another Source of Pacemaker Interference?
from Heartwire — a professional news service of WebMD
May 15, 2007 (Denver, CO) - Perhaps you've seen them--compact, electronic devices with complex circuitry and sophisticated programming, a state-of-the-art battery, and a single external wire separating into two leads distally. Enough to serve a third of the US population have been sold, yet they are not reimbursable.
The iPod (Apple, Inc) is seemingly everywhere, but any pumping out tunes within a few inches of implanted pacemakers might be altering their sensing functions or telemetry, suggests a study that may add to the list of potential sources of pacemaker electromagnetic interference [1].
Jay P Thaker, a high-school student from Okemos, MI, who had conceived the study and conducted it with physician investigators at Michigan State University, in Lansing, tested several iPod models for any measurable effects on pacemakers in 100 patients. The implanted devices, which were from various manufacturers, included 89 dual-chamber and 11 single-chamber models. Thaker presented the results here last week at the Heart Rhythm Society 2007 Scientific Sessions.
Thaker and his coauthors conducted two tests using each of four iPod models on each patient. The tests consisted of allowing the media players to operate for five to 10 seconds when positioned two inches from the implanted pulse generators, followed by interrogation of the devices' event history. Of the 800 individual tests, 13.5% of them in 19 patients were associated with oversensing events, defined as spurious sensed events associated with atrial or ventricular inhibition, mode switching, or high paced rates. Telemetry interference occurred in 37% of the tests in 32 patients. And there was one instance of pacing inhibition, defined as "failure to pace when pacing was expected." On that occasion, the iPod's inhibiting effect on ventricular pacing was transient but reproducible, Thaker said.
During 1200 more tests in 25 of the patients, the team observed that oversensing and telemetry interference were both independent of lead configuration (unipolar vs bipolar), that oversensing was independent of pacing mode (AAI vs VVI vs DDD), and that telemetry interference events were significantly fewer for AAI pacemakers than for devices in either the VVI or DDD modes. Interference events were reproducible, Thaker said; they were seen to occur at about the same rates on different testing days.
"Although the observed interference was not life threatening, the abnormal histogram findings [high atrial or ventricular rates] may be misinterpreted as atrial fibrillation or ventricular tachycardia and could lead to inappropriate therapy or investigations."
Thaker's presentation met with both praise and skepticism from physicians in the audience. During the question-and-answer period, Dr Marcelo E Helguera (Hospital Italiano de Buenos Aires, Argentina) questioned the significance of the findings. He said that the kind of interference documented in the study is observed "all the time" at his center during pacemaker interrogations using a telemetry wand and can come from a variety of consumer electronic devices, such as video cameras or digital cameras. Such interference, he said, "is not a clinically relevant phenomenon."
Dr Richard G Trohman (Rush University, Chicago, IL), cochair of the session that featured Thaker's presentation, said further studies of any iPod effects from distances further than two inches are called for. "I'm guessing that unless a person has a device and puts a working iPod in a shirt pocket right over the device, that this will not be clinically important."
According to a press release issued by the Heart Rhythm Society, Thaker had approached Dr Krit Jongnarangsin (University of Michigan, Ann Arbor) about conducting the study after reading news reports about pacemaker interference from cell phones. Jongnarangsin and Thaker then teamed with researchers at Michigan State to carry it out.
In the press release, Thaker, whose parents are both physicians and whose father is an electrophysiologist, said, "Our findings are disconcerting because although the typical pacemaker patient may not be an iPod user, they are often in close contact with grandchildren or other young people who are avid users."
"I (heart) my iPod--or, um, maybe not" [2]
Clinically relevant or not, the iPod study's findings found their way around the world in one form or another. How serious they seemed to be, however, depended on where one read them.
The widely circulated article from Reuters reporter Debra Sherman was originally published with the matter-of-fact headline, "iPods can make pacemakers malfunction: study" [3]. The article began, "iPods can cause cardiac implantable pacemakers to malfunction by interfering with the electromagnetic equipment monitoring the heart, according to a study presented by a 17-year-old high school student to a meeting of heart specialists on Thursday."
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作者:admin@医学,生命科学 2010-09-24 17:11
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