A Medical Device Daily

Medtronic (Minneapolis) has notified doctors of battery-related issues in certain pacemakers that it said are not putting patients at risk, although one issue has been linked to doctors unnecessarily removing and replacing devices.

The company plans to roll out fixes through a software update by midyear, it said in a letter addressed "Dear Healthcare Professional" and dated "February 2010." The letter was sent out worldwide.

The issues involve "EnRhythm" pacemakers, which are sold worldwide, and "EnRhythm MRI" versions, which are sold in Europe and designed to be compatible with MRI scans.

The coming fix will slightly reduce battery longevity, Medtronic said, but the devices are expected to still last 8 1/2 to 10 1/2 years depending on settings.

"There have been no reports of patient injuries and the devices will continue to deliver therapy, as needed," the company said in a statement Tuesday.

"Medtronic expects to release a software update this summer that will address these issues," the company also said. "We want to inform physicians in advance of when they may see this issue to avoid unnecessary device replacements."

The unneeded replacements stem from confusion about battery-voltage readings during doctor checks that were lower than the level tracked by the pacemakers themselves. This tracking is done to provide data for a so-called elective replacement indicator. Doctors, meantime, check pacemakers during routine office visits with a wand placed over the devices, which are implanted in the chest.