P2: Impella Smart Assist Technology and Hemodynamics Management in Cardiogenic Shock Management

Background: Smart Assist Impella pumps provide enhanced hemodynamic metrics via real-time assessment of aortic pressure (AoP), left ventricular pressure (LVP), cardiac output (CO) and cardiac power output (CPO). These data can constitute powerful management tools for clinicians yet information on the Smart Assist Technology algorithms and calculations remains scarce. This case reports illustrates the importance of an in-depth understanding of this newer technology to effectively manage cardiogenic shock patients on Impella support. Method: A 64yo man with cardiogenic shock supported with Impella 5.5 as a bridge to transplant had been on support for 27 days, with stable hemodynamics on P8, flowing 4.5 LPM. On day 28 patient experienced suction alarms and LVDP <-40mmHg prompting the team to reduce P level, administer fluid and attempt Impella repositioning. None of the interventions resolved the issue and consideration was given to reducing support to P2 and weaning or exchanging the Impella. The pump appeared correctly positioned by echo and hemolysis markers were negative. Careful review of patients’ data demonstrated a discrepancy between the transduced radial artery MAP at 73 mmHg and the aortic pressure measured by the Impella fiber optic sensor at 42 mmHg. This prompted a review of the LVP metric. The Impella Left ventricular pressure is calculated in real time by subtracting from the AoP the differential pressure gradient between pump outlet and inlet as derived from the motor current. An erroneous Ao signal input will result in an inaccurate LVP. Furthermore, the Impella suction alarm algorithm utilizes a sustained low LVDP as a trigger and can thus be triggered erroneously if the Ao signal is inaccurate. The suctions alarms and the low LVP were determined to be caused by drifting data feed from the Impella aortic fiber optic sensor. An Impella Ao signal bedside recalibration based on transduced MAP resolved the suction alarms. Result A drifting AoP signal resulted in an erroneous LVP measurements and subsequent suction alarms. Fiber optic technology does not require periodic calibrations once in vivo. Per IFU, the accuracy of the Ao is 1.9mmHg and the accuracy of the LV is 8.8 mmHg. In this case, the recalibration of the AO signal resolved the suction alarms and low LVP. Decision was made to not undertake an invasive pump exchange and continue supporting the patient on the implanted pump managing the metrics with daily manual recalibration. The patient was supported for an additional 17 days demonstrating optimal perfusion pressure and LV unloading and successfully underwent orthotopic heart transplant on Impella day 45. Conclusion: Impella Smart Assist technology is a powerful tool to manage patients’ hemodynamics. An in-depth understanding of the technology and its algorithms is crucial in delivering optimal patient care and preventing erroneous data feed from guiding hemodynamic management.Figure 1. Impella Smart Assist metrics. A. Stable on P8. B. Suction alarm generated by low LVDP. C. Persistent alarms despite fluid bolus and lower P level. D. Suction alarm resolved by Ao recalibrationFigure 2. LVP Calculation