Manufacturer's investigation conclusion: review of the submitted log files confirmed power/estimated flow fluctuations.A specific cause for the power/estimated flow fluctuations could not be conclusively determined through this evaluation, and a direct correlation with heartmate ii left ventricular assist system (lvas), serial number (b)(6), could not be conclusively established.Power/flow elevations were noted by the account on (b)(6) 2020 during a routine visit.Labs were taken, and the patient was asymptomatic and doing well with stable blood pressure.The cause of the elevations was reportedly not determined, and the plan was to continue to monitor the patient.The patient remains stable at home as of (b)(6) 2021 with no reported alarms.A review of the submitted log files from (b)(6) 2020 and from (b)(6) 2020 found that the pump maintained a stable speed above the low speed limit without issue.Fluctuations in power and estimated flow were observed; however, power trended flat over time.Of note, multiple pulsatility index (pi) events were captured throughout the log files.The system appeared to be operating as intended, and there were no notable alarms active in the log file.The patient remains ongoing on (b)(6) with no related issues reported at this time.It was reported that the device operated as expected.The relevant sections of the device history records for (b)(6) were reviewed and showed no deviations from manufacturing or quality assurance specifications.The implant kit shipped on 14apr2017.The heartmate ii left ventricular assist system (lvas) instructions for use (ifu), is currently available.The ifu provides an explanation of each of the pump parameters, including pump power and flow, in sections 1 "introduction" and 4 "system monitor".Section 1 (under "explanation of parameters") explains that device power is a direct measurement of pump motor voltage and current.Changes in pump speed, flow, or physiological demand can affect pump power.Abrupt changes in power should be evaluated for cause.In addition, device flow and power generally retain a linear relationship at a given speed.However, while power is directly measured by the system controller, the reported flow is estimated, based on power.Since the flow displayed on the system controller is a calculated value, it becomes imprecise at the low and high ends of the linear power-flow relationship.Section 4 (under ¿low speed limit¿) addresses pi events as well as potential causes.It is explained that if the system detects a pi event, the pump speed automatically drops to the low speed limit and slowly ramps back up at a rate of 100 rpm per second to the fixed speed setpoint.In addition, section 4 cautions that no single parameter is a surrogate for monitoring the clinical status of the patient, and the changes in all parameters should be considered when assessing any clinical situation.Section 6 "patient care and management" (under "pump performance monitoring") addresses assessing pump flow and explains that pump performance is sensitive to changes in systemic vascular resistance and left ventricular filling.No further information was provided.The manufacturer is closing the file on this event.
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