Medtronic Inc in July said it sent a letter to healthcare professionals warning them about the potential for reduced battery performance in a small percentage of its SynchroMed II Implantable Drug Infusion Pumps.

As of May 31, there were 55 confirmed cases of the issue from some 139,653 SynchroMed II pump implants worldwide. The battery issue does not include Medtronic's external insulin pumps for diabetes.

The medical device maker had issued its first warning in July 2009.

The company, which makes a broad range of heart, neurological and spinal devices, said it is not recalling the product, nor is it recommending surgical removal of the devices unless a patient's pump demonstrates reduced battery performance.

The company said its analysis indicates that the problem is related to the formation of a film within the pump battery that may impact battery performance. This can lead to the sudden loss of therapy and the return of underlying symptoms and/or withdrawal symptoms, Medtronic said.

Patients receiving intrathecal baclofen therapy are at risk for baclofen withdrawal syndrome, which can lead to a life-threatening condition if left untreated.

Medtronic said it encourages patients to carry their patient identification cards with them at all times and to contact their physicians immediately if they experience a return of symptoms or hear a device alarm.

It said it is working to obtain U.S. approval for a battery design change intended to prevent the issue from occurring in future pumps. The design change has been implemented in several regions, including Europe, Australia, New Zealand, Canada, Africa and India.

Reuters Health Information © 2011