Following the submission of the initial mdr report the suspect controller was returned to heartware for investigation.
Various analyses were conducted and reviewed in order to evaluate the performance of the controller in relation to the reported event.
These included clinical evaluation, review of manufacturing documentation, visual and functional examination, and review of controller log files.
Functional testing of the returned controller showed that the device (including motor control circuits) performed all functions as intended within specification and with no fault alarms or errors.
The controller power and driveline connections were tested and were confirmed to be secure and properly functioning.
Review of the controller log data file indicated that both batteries were changed just prior to the reported event.
The log files further indicated that at the time of the event there was a condition present in which the motor control software was no longer driving the pump's motor controller circuit; this is referred to as "loss of commutation".
When commutation is halted, the pump stops.
Review of the controller log alarm and event files showed a low flow alarm followed by a controller fault alarm (6-seconds later).
The patient was found alone and unresponsive with the controller alarming approximately three hours post event.
Log analysis confirmed the reported event that the pump had stopped.
The exact cause of the loss of commutation cannot be conclusively determined; however, we suspect that an electrostatic discharge (esd) through the exposed controller power ports during battery replacement caused or contributed to data corruption in the pump motor controller resulting in loss of commutation.
Additional information: the post mortem medical report provided by the hospital indicated that the patient suffered from ehlers-danlos syndrome with significant aortic and mitral valve insufficiency which greatly contributed to the risk of mortality in the event of a pump stop.