The purpose of this study is to evaluate the effectiveness and safety of nafamostat mesilate compared with unfractionated heparin for anticoagulation in patients with ECMO after cardiac surgery.

Selecting patients who require systemic anticoagulation as the study subjects from patients undergoing extracorporeal membrane oxygenation assistance after cardiac surgery. Randomly divided into the nafamostat mesilate group and unfractionated heparin group. To evaluate the efficacy and safety of nafamostat mesilate by comparing the incidence of bleeding and thrombosis within the target anticoagulant level range between two groups of patients during ECMO

Inclusion Criteria:

1. Age ≥ 18 years old
2. VA-ECMO or VV-ECMO was accepted after cardiac surgery.
3. The ECMO treatment team believes that systemic anticoagulation is needed
4. Sign the informed consent form

Exclusion Criteria:

1. The researchers believe that there are other causes of active bleeding that are not suitable to participate in this study.
2. Long-term use of anticoagulants before establishment of ECMO
3. Antiplatelet drugs were used before the establishment of ECMO
4. Severe liver insufficiency
5. Connective tissue disease
6. There is a history of allergy to heparin or nemolastat mesylate.
7. Pregnant
8. Previous diagnosis of heparin-induced thrombocytopenia
9. Expect to die within 48 hours
10. ECPR