39: Heparin Induced Thrombocytopenia on V-V ECMO - Case Report

Background: Heparin-induced thrombocytopenia (HIT) is a serious immune-mediated complication of heparin exposure, characterized by a reduction in platelet count and a paradoxical hypercoagulable state with potentially catastrophic thrombotic events. Patients supported with extracorporeal membrane oxygenation (ECMO) are particularly vulnerable due to prolonged heparin exposure and circuit-related activation of coagulation. We report a case of HIT developing during veno-venous (VV) ECMO support for severe acute respiratory distress syndrome (ARDS). Case Description: A 40-year-old male presented with severe ARDS secondary to H1N1 pneumonia and refractory hypoxemia. Following failure of prone ventilation, VV-ECMO was initiated. Systemic anticoagulation was started with unfractionated heparin, monitored using activated clotting time every two hours. During the ECMO course, the patient developed recurrent oxygenator failure due to clot formation, necessitating multiple oxygenator exchanges. Concurrently, he developed thrombocytopenia and a right lower limb deep venous thrombosis extending into the internal iliac vessels. HIT was suspected based on a high 4T score and subsequently confirmed. Anticoagulation was transitioned from heparin to bivalirudin infusion. An inferior vena cava filter was placed for thromboembolic protection. The patient’s course was further complicated by refractory hypoxia, episodes of bradycardia with cardiac arrest, and multiple blood transfusions resulting in transfusion-related acute lung injury, further impairing gas exchange. Despite these challenges, the patient was successfully decannulated from VV-ECMO and discharged home. Conclusion: This case highlights the importance of early recognition of HIT in ECMO patients presenting with thrombocytopenia, circuit thrombosis, and oxygenator failure. Prompt transition to non-heparin anticoagulation and multidisciplinary management are essential to mitigate thrombotic complications and achieve favorable outcomes during VV-ECMO support.