The Fridley, Minn.-based medical device titan said the change is aimed at improving the long-term rate of non-recoverable motor stall in the SynchroMed II devices, estimating that pump survivability rates at six years for stalled pumps to be 97.3%2 with on-label drugs and 91.1%2 with off-label drugs.
“The most common contributing factor to motor stall is shaft wear and this is observed in 59% of SynchroMed II pumps returned and analyzed for motor stall,” the company said in a November letter to physicians. “Engineering testing estimates that this new design change addresses over 99% of shaft wear and will decrease the occurrence of motor stall.”
Medtronic said that all SynchroMed II pumps are now made using the design change, although quantities are limited.
“To ensure your patients have access to uninterrupted therapy, pumps manufactured prior to this latest change will remain available. Once there is sufficient inventory of the pumps with the new design, we will no longer distribute pumps manufactured prior to this change,” the company said, noting that it’s the third change aimed at the motor stall issue. “Medtronic initiated distribution of SynchroMed II pumps with the first two design changes in January 2016. These design changes addressed motor corrosion of the drive gear and internal electrical shorting, observed in 2% and 14% respectively, of pumps returned and analyzed for motor stalls. Engineering testing estimates that these design changes address over 93% of corrosion of the drive gear and over 96% of internal shorting.”
SynchroMed II ran into trouble back in July 2009, when reports surfaced about the formation of a filmy substance within the pump battery that could lead the device to shut down suddenly. Returned product analysis proved the failed devices’ alarms functioned as designed, Fridley, Minn.-based Medtronic said in July 2011.
There were 55 confirmed cases of the devices failing as of May 32, 2011, Medtronic said back then, including 1 death attributed to baclofen withdrawal syndrome.
In a letter dated April 2017 sent to European doctors, Medtronic updated the numbers for pumps with batteries made from March 2005 through December 2010. The company said there was a 0.13% cumulative probability for pump failure at 72 months due to the batter issue.
The SynchroMed II and SynchroMed EL pumps were recalled in 2013 because they unintentionally delivered drugs during the priming bolus procedure and patients were at risk for over-infusion in the cerebrospinal fluid followed by a period of reduced drug delivery. As of July 5, 2016, there were 103 incidents of over-infusion among the more than 238,000 SynchroMed II pumps implanted since the device came to market (0.04%).