IPOD interference with PM

• by maestro
• 2008-03-29 03:03:35
• General Posting
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Quote from testing:
By the way, none of the researchers provided information on Conflict of Interest.



"Among 800 tests on 100 patients (mean age 77.1) with single- or dual-chamber pacemakers, the findings included:


51% of patients and 20% of calibration tests in the office showed some type of interference.
19% of patients and 7.88% of these tests indicated spurious sensing in either the atrial or ventricular channel detected on the device rate histograms.
32% of patients and 11.75% of these tests indicated interference events only on the display screen of the programmer that were not registered in rate histograms.
None of the patients reported any symptoms.

Interference did not differ by pacing configuration or pacing mode, but most events were seen with the iPod 3G and Photo whereas few occurred with the Nano and Video.


High atrial rates on histograms could lead to unnecessary interventions if misinterpreted as atrial fibrillation, atrial lead fracture, or a loose set screw, the researchers said. High rates in the ventricular channel could likewise raise concerns about ventricular tachycardia or ventricular lead problems, they said.


There were no mode switch episodes observed, possibly because of the short duration of iPod exposure, the investigators said. The lack of pacing inhibition was expected because most patients had a native rhythm at the time of iPod testing and were not paced.


"Telemetry interference may be clinically significant," they concluded, "especially as these devices move toward remote monitoring and possibly remote programming."


However, researchers at Children's Hospital Boston were skeptical. They hadn't seen a clinical effect among their young patients, who are more likely to use portable music players on a daily basis.


So Charles I. Berul, M.D., and colleagues, prospectively studied all 51 of their patients at Children's Hospital who had active pacemakers or ICDs.


Each patient (median age 22) was exposed to the iPod Nano and Video as well as SanDisk Sansa and Microsoft Zune players.


When the players were put on the patients' chests along with the device programmer, the findings included:


41% of patients and 14% of tests showed interference with telemetry programmer communication with pacemakers or ICDs.
No surface electrocardiogram changes during any of the 255 tests.
No oversensing, undersensing, mode reversion, asynchronous pacing or abnormal functioning.
No inappropriate ventricular tachycardia sensing events or shocks.
No interaction between players and routine functioning of the pacemakers or ICDs.

One of the 51 patients complained of symptoms -- mild tingling and burning at the site of the pacemaker -- but the symptoms appeared to be related to the programmer because no interference with the pacemaker was noted and the sensation remained even when the music players were moved away.


Interference with telemetry included abnormal electronic "noise" in the atrial and ventricular recording channels, lost marker channel indicators, and loss of communication with the device programmer.


The interference was seen across all ICD and pacemaker types but appeared to be more common with digital media players with larger storage size, possibly because of larger hard drives or larger batteries, the researchers said.


However, moving the music players six inches from the patient restored lost connections between programmer devices and pacemakers or ICDs and brought tracings on the device programmer back to normal.


This agreed with findings reported earlier this year by FDA researchers suggesting iPods generated weak electromagnetic fields that extended only about 1 cm from the case (See: Cardiac Pacemakers and iPods Can Coexist Without Discord).


Although it might not be a good idea to stick an iPod in a shirt pocket, it doesn't appear to be dangerous, said Gregory Webster, M.D., of Children's Hospital Boston, who was a co-author.


Nevertheless, "as a precaution, patients might be advised to keep their digital music players at least six inches away from their device pocket, and potential electromagnetic interference should always be considered when assessing pacemaker/ICD stored episodes," his group concluded.


This is especially true for all portable electronic devices, including cell phones, during arrhythmia device interrogation and programming, said Drs. Krahn and Yee.


These studies, though, looked only at short-term use of media players on the order of seconds rather than the hours patients often use them, Dr. Webster noted. It's likely that long-term use would be safe as well if patients keep the player at least six inches from their pacemaker or ICD, he said.


Dr. Berul's study was supported by the Boston Children's Heart Foundation. Dr. Berul reported receiving prior research funding for an unrelated project from Medtronic and Guidant, and being a consultant for Medtronic. Co-authors reported consulting for St. Jude Medical and Biosense Webster.



Neither Dr. Thakur's group nor the editorialists provided information on conflicts of interest.


Primary source: Heart Rhythm
Source reference:
Webster G, et al "Digital music players cause interference with interrogation telemetry for pacemakers and implantable cardioverter-defibrillators without affecting device function" Heart Rhythm 2008; 5: 545-550.

Additional source: Heart Rhythm
Source reference:
Thaker JP, et al "Electromagnetic interference with pacemakers caused by portable media players" Heart Rhythm 2008; 5: 538-544.