Increased risk of purge system malfunction after Impella 5.0 replacement: a case series

The Impella 5.0 is an axial-flow percutaneous ventricular assist device used in patients with cardiogenic shock. Although the recommended period of use is 10 days or less, weaning can be delayed because of ongoing hemodynamic instability. In clinical practice, this device sometimes malfunctions during long-term management with heparin and must be replaced; however, the relationship between the duration of support with the initial and replacement Impella 5.0 and the changes in value of the purge system has not been fully elucidated. From July 2018 to May 2021, Impella 5.0 was implanted and used for more than 10 days in 11 patients at our institution. Four patients required Impella replacement because of device malfunction and the second Impella had purge system malfunction in all cases. The second Impella was used for a significantly shorter time than the first Impella (p = 0016). We calculated the ratio of purge pressure to purge flow rate and found that the ratio exceeded 50 mm Hg/mL/h in all cases with purge system malfunction. In conclusion, it is important to construct a treatment strategy considering the duration of use, because the risk of purge system malfunction is high after replaced Impella 5.0.