Surgically Implanted Impella Device for Patients on Impella CP Support Experiencing Refractory Hemolysis

The Impella CP (Abiomed Inc., Danvers, MA) is widely used in cardiac catheterization laboratories for patients presenting with cardiogenic shock, but it is also known to cause significant hemolysis. The risk of hemolysis can be reduced by properly positioning the device, ensuring an adequate volume status, and using full anticoagulation strategies; however, in some cases hemolysis persists. We present a case series of eight patients that were diagnosed with cardiogenic shock, underwent Impella CP placement, and then suffered from refractory hemolysis which was treated by upgrading the Impella device to the 5.0 or 5.5 version. Fifty percent (4/8) of the patients in this series were already receiving continuous renal replacement therapy, and the levels of plasma free hemoglobin (pFHb) and lactate dehydrogenase continued to increase after the implantation of the Impella CP. The median time between Impella CP placement and the diagnosis of refractory hemolysis was 16.5 hours (interquartile range [IQR], 8.0-26.0). The median time between the diagnosis of hemolysis to Impella upgrade was 6.0 hours (IQR, 4.0-7.0). A total of 87.5% (7/8) of patients experienced a drop in pFHb to below 40 mg/dl at 72 hours post-Impella upgrade, and they were discharged without any further need of dialysis. One patient expired due to irreversible multiple organ failure. We propose that early identification of hemolysis by close monitoring of pFHb and upgrading to the Impella 5.5 reduces hemolysis, prevents further kidney damage, and significantly improves clinical outcomes.