Background: Urgent cardiopulmonary bypass (CPB) in acute heparin-induced thrombocytopenia (HIT) presents a clinical challenge. Direct thrombin inhibitors carry bleeding and monitoring risks, while re-exposure to unfractionated heparin (UFH) risks thrombosis in the presence of pathogenic HIT antibodies.

Objective: To evaluate whether a combined regimen of therapeutic plasma exchange (TPE) and high-dose intravenous immunoglobulin (IVIg) enables safe intraoperative UFH administration in acute HIT.

Methods: Five consecutive patients with confirmed acute HIT (PF4-heparin ELISA OD ≥1.5; serotonin release assay [SRA] ≥50%) requiring urgent CPB underwent 3–4 sessions of TPE (1 plasma volume each; fresh frozen plasma replacement), followed by two IVIg infusions (1 g/kg each). Serial PF4-heparin ELISA, SRA, and PF4-dependent P-selectin expression assay (PEA) were measured. UFH dosing followed standard CPB protocols and was reversed with protamine.

Results: Post-TPE, functional assays normalized (SRA <20%), while ELISA optical densities remained positive (0.8–1.2), demonstrating antigen-functional dissociation. PEA remained elevated (30–45%) until after the first IVIg dose and normalized (<19%) only after the second. All patients received UFH (28 000–36 000 U) during CPB without thrombotic or major bleeding complications. Platelet counts recovered to baseline by postoperative days 5–7.

Conclusion: A protocol of preoperative TPE followed by high-dose IVIg effectively removes and neutralizes HIT antibodies, enabling safe UFH use during urgent CPB in acute HIT. Serial functional assays (SRA, PEA) are essential to guide timing of heparin re-exposure. This combined approach offers a reproducible strategy for centers facing resource or bleeding-risk constraints with non-heparin anticoagulants.

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2025
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