A new study has found that an iPod, placed too close to a pacemaker, can pose a serious problem, according to HealthDay News on Thursday.

"The portable music players caused pacemakers to malfunction in 50 percent of patients, according to the study by Jay Thaker, a Michigan high school senior, that was expected to be presented Thursday at the Heart Rhythm Society's annual meeting, in Denver," Steven Reinberg wrote.

Moreover, a pacemaker stores a history of the heart's rhythms, and a pacemaker disrupted by an iPod could cause a physician to misinterpret the heart's history.

In the study, which included doctors from Michigan State University and the University of Michigan, Mr. Thaker held an iPod 2 inches (5 cm) from the chests of 83 people with pacemakers for 10 seconds. Telemetry interference occurred 29 percent of the time, and the pacemaker over sensed the heart function 20 percent of the time.

In some cases, the effects occurred with the iPod was as far as 18 inches (46 cm) from the patient. Dr. Edwin Kevin Heist, a cardiac electrophysiologist at Massachusetts General Hospital, agreed that iPods can be a danger to patients with pacemakers.

Dr. Heist also warned that an iPod, placed too close, could pose a problem for implanted pacemaker defibrillators and could cause an inappropriate and painful shock. He advises his patients that they can still use cell phones and iPods, but to be careful with the placement and warned: "Patients with a pacemaker could safely use an iPod, just don't put it over the device."

In conducting the research, Mr. Thaker acknowledged that pacemaker patients aren't the typical iPod user. "But because the music players are so common, people with pacemakers need to be aware of the risk," he said.