Microaxial Flow Pump Thrombosis Presenting as Predominant Direct Hyperbilirubinemia

Clinically significant hemolysis and device thrombosis are uncommon with the Impella 5.5, and presentation with predominant direct hyperbilirubinemia has not been described.

A 57-year-old man with refractory cardiogenic shock underwent Impella 5.5 placement as a bridge to transplant. He developed severe direct-predominant hyperbilirubinemia (total bilirubin 18.4 mg/dL; direct 11.7 mg/dL) with rising lactate dehydrogenase (1,395 U/L) and undetectable haptoglobin, despite normal purge pressures and no device alarms. Duplex ultrasonography excluded biliary obstruction. Device exchange revealed a large, organized thrombus in the motor/outflow housing, after which hemolysis was resolved, and biochemical improvement followed, allowing successful bridging to heart transplantation.

Occult Impella thrombosis may present as direct-predominant hyperbilirubinemia, an atypical pattern that can mimic hepatobiliary disease and confound the diagnostic evaluation.

Direct hyperbilirubinemia during Impella support should prompt evaluation for subclinical device thrombosis. Timely device exchange can reverse hemolysis and preserve transplant candidacy.