ID:127 FC-PC1-1 Managing heparin and urokinase during ECMO and EKOS for pulmonary embolism: a perfusionist single–center experience

Background: Ultrasound–assisted catheter–directed thrombolysis (EKOS) with urokinase (UK) is increasingly used for high–risk pulmonary embolism (PE), but perfusion–driven anticoagulation strategies during concomitant extracorporeal membrane oxygenation (ECMO) remain poorly defined. Methods: From December 2020 to January 2026, 20 adults with CT–confirmed PE underwent EKOS with UK at a tertiary cardiac center; 3 required concomitant ECMO for cardiogenic shock or cardiac arrest. Perfusion management targeted continuous unfractionated heparin titrated by bedside activated clotting time (ACT) with protocolized 4–hourly fibrinogen measurements during UK infusion. Demographics, PE risk, ECMO configuration, ACT–fibrinogen trajectories, survival, and major bleeding (especially intracranial hemorrhage, ICH) were reviewed. Results: Overall survival among EKOS patients was high, but outcomes were heterogeneous in the ECMO subgroup (1/3 survival). The survivor showed profound initial hypofibrinogenemia (≈70–90 mg/dl) that recovered to >400 mg/dl over 3 days, with ACT maintained around 150–190 seconds under stable heparin doses, and no major bleeding before ECMO explant. In contrast, one patient progressing to brain death after in–hospital cardiac arrest had ACT 170–210 seconds with frequent heparin adjustments and preserved fibrinogen mostly >200 mg/dl, yet developed fixed pupils and ultimately died. Another V–VA ECMO patient, managed with ACT 140–200 seconds and fibrinogen generally 200–400 mg/dl, suffered catastrophic ICH after initial weaning. Conclusion: From a perfusionist perspective, combining ECMO, systemic heparin, and EKOS–UK for PE exposes patients to a very narrow therapeutic window between circuit thrombosis and malignant bleeding, including ICH, even when ACT and fibrinogen are tightly monitored. These data highlight the need for ECMO–specific anticoagulation and fibrinolysis protocols, and for prospective studies to define safe ACT and fibrinogen targets during catheter–directed thrombolysis