Washington, March 30 : Disapproving a recent suggestion that errant electronic noise from iPods may cause implantable cardiac pacemakers to malfunction, cardiac electrophysiologists at Children's Hospital Boston say that they have not found any such effect in hundreds of children and young adults requiring pacemakers for their heart conditions.
"Many of our pacemaker patients have iPods and other digital music players, and we've never seen any problem. But kids and parents bring up this concern all the time, prompting us to do our own study," says Dr. Charles Berul, director of the Pacemaker Service at Children's.
Dr. Gregory Webster, a cardiac fellow in training at Children's, directed a team of electrophysiology nurses and physicians to conducts tests on 51 patients coming in for appointments between September and December last year.
The average age of the subjects was 22, ranging from six to 60, and all patients had active pacemakers or implantable cardioverter-defibrillators (ICD).
The pacemakers and ICDs were tested against four digital music players - two kinds of iPods (Apple Nano and Apple Video), SanDisk Sansa and Microsoft Zune.
All patients were lying down during the tests, and each digital player was placed directly over the pacemaker or ICD.
In their study report, reported in the journal Heart Rhythm, the researchers revealed that there was no interference with intrinsic device functioning, and that patients' electrocardiographic (EKG) recordings did not show any change in any of the 255 tests.
"This provides reassuring evidence that should allay the fears of people using iPods and other digital music players," says Berul, the study's senior investigator.
But in 41 percent of patients, the music players interfered with telemetry or communications between the programmer - a computerized device used by physicians to check and recalibrate the pacemaker/ICD - and the pacemaker or ICD itself.
The interference picked up in 29 of 204 tests went away when the digital player was moved six inches or more from the device, and did not compromise device function.
The larger digital players (Zune and Apple Video) caused more interference with telemetry than the small players.
Based on their observations, the researchers came to the conclusion that patients should nto use digital music players while the doctor is trying to reprogram their device.
"If the iPod is right in the field, the programmer might not be able to communicate with the pacemaker or ICD effectively," Webster says.
The researchers, however, concede that their testing was only short-term.
"We can't conclude that it's completely safe to have an iPod right on top of the device for hours at a time. That's why we suggest the precaution of keeping it at least six inches away," Berul says.