Upon failure of a primary control unit for controlling an implanted pump in a ventricle assist system enhancing blood flow in a patient, an initial backup control unit is substituted for the failed unit. An interface device is connected to one of the initial backup control unit or the primary control unit. Patient-unique data is downloaded to the interface device to create a transfer data set. The initial backup control unit is connected to the implanted pump as a new primary control unit. The interface device is connected to a replacement backup control unit. The transfer data set is uploaded from the interface device to the replacement backup control unit. The transfer data set on the interface device is modified after uploading to prevent a subsequent uploading from the interface device to another control unit.
