Chorda Tendinea Obstruction of Impella Causing Massive Hemolysis Detected by Methemoglobinemia: A Case Report.

The Impella microaxial flow pump is increasingly used in cardiogenic shock and high-risk coronary interventions. Hemolysis is a frequent complication, but established markers lack bedside availability. We report the first case of Impella obstruction by a chorda tendinea, causing massive hemolysis detected through severe methemoglobinemia. A 60-year-old male with non-ST-elevation myocardial infarction and cardiogenic shock underwent protected percutaneous coronary intervention with Impella CP SmartAssist support. After 42 hours, motor current increased abruptly while purge flow remained unchanged. Despite correct positioning and optimized volume status, hemoglobin fell from 9.2 to 4.6 g/dl within 14 hours, methemoglobin peaked at 10.2%, and anuric kidney injury developed. Device explantation revealed a native filamentous structure incorporated in the impeller, morphologically consistent with a chorda tendinea. Hemolysis resolved promptly post-explantation. The patient recovered and was discharged home after three months. Mobile cardiac structures can cause impeller obstruction leading to severe hemolysis. Methemoglobinemia-measured on routine blood gas analysis-may serve as an early indicator of evolving hemolysis during mechanical circulatory support and warrants prospective validation. Increased motor current with unchanged purge flow may differentiate intraluminal obstruction from thrombosis and guide targeted intervention.