Medtronic, a medical technology company, advised physicians on July 8, 2011 about an issue with some of their SynchroMed II implantable drug infusion pumps. The batteries, designed to last seven years, are failing after four to six years. The pumps involved do not include the Medtronic external insulin pumps for diabetes.
The pumps are used to provide pain relief medications, and to treat spasticity--a condition where muscles contract uncontrollably. When the batteries fail early, one of several different battery alarms can be activated to let the patient know what is going on, including a premature End of Service alarm.
Patients whose pumps fail experience a return of underlying symptoms, and those using pain relief medications experience withdrawal symptoms as well. There have been no reported patient deaths. For those patients being treated for spasticity, it's possible that the sudden absence of their medications could lead to a life-threatening condition.
Medtronic first warned of this issue in July of 2009 when it reported nine cases of reduced battery performance. The latest advisory reports 55 confirmed cases as of May 31, 2011, out of almost 140,000 pumps in use.
The formation of a film within the pump battery seems to be the primary cause of early battery failure. Medtronic has changed the battery design to prevent this issue from occurring again, but is still working to obtain US approval for the change.
Medtronic does not recommend the removal of implantable pumps that have not had problems with batteries, because of the surgical risks, and the low probability that a unit will be affected.
