Anticoagulation in extracorporeal circulation using recombinant hirudin: a case report

Area of Science:

• Hematology
• Immunology
• Pharmacology

Background:

• Heparin-induced thrombocytopenia (HIT) is a serious immune complication of heparin therapy, mediated by antibodies against heparin-platelet factor 4 complexes.
• HIT can manifest as HIT I (mild, transient thrombocytopenia) or HIT II (severe, delayed thrombocytopenia with thrombotic risk).
• Alternative anticoagulants like recombinant hirudin (r-hirudin) are used when heparin is contraindicated.

Observation:

• A patient with prosthetic aortic valve endocarditis and HIT II experienced massive postoperative bleeding.
• The bleeding was attributed to free-circulating r-hirudin, detected via ecarin-clotting time.
• The presence of a hemofilter was implicated in the excessive r-hirudin levels.

Findings:

• The case demonstrates a critical interaction between r-hirudin and hemofiltration, leading to supratherapeutic anticoagulation.
• Massive bleeding occurred despite the use of an alternative anticoagulant, highlighting potential complications beyond direct HIT.
• Immunologic confirmation of HIT via heparin-induced platelet aggregation assay is crucial for diagnosis.

Implications:

• This case underscores the importance of vigilant monitoring of alternative anticoagulants, such as r-hirudin, especially in patients with HIT.
• The use of hemofilters in conjunction with r-hirudin requires careful consideration due to potential for excessive drug levels and bleeding complications.
• Clinical practice should emphasize tailored anticoagulation strategies and close monitoring to prevent severe bleeding events in HIT patients.