iPods have joined late-opening restaurants and children playing on old people's lawns on the list of things that can make pacemakers go haywire.

A new study, presented today to a meeting of heart specialists by a 17-year-old high school student, suggests that the music-playing device can interfere with the electromagnetic equipment in implanted pacemakers.

Reuters reports 100 pacemaker patients (with a mean age of 77) were examined in the study.

Holding the iPod just two inches away from their chests for 5 to 10 seconds was enough to cause electrical interference half the time. In some cases, iShenanigans could be detected as far as 18 inches away. The interference usually just caused the equipment to misread the heart's pacing, but one case caused the pacemaker to stop working entirely.

But before you buy grandpa a gift to speed up that inheritance money; none of the symptoms are life-threatening, and the pacemakers returned to normal when the iPods were shut off.

Jay Thaker, a student at Okemos High School in Michigan, co-authored the the report with a friend of his father, Dr. Krit Jongnarangsin, an assistant professor in the Division of Cardiovascular Medicine at the University of Michigan.

The iPod was the only portable music player tested in the study.

The reason why it this hasn't been caught before?

"Most pacemaker patients are not iPod users," Jongnarangsin said.