Persisting autoimmune heparin-induced thrombocytopenia after elective abdominal aortic aneurysm repair: a case report
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Persisting autoimmune heparin-induced thrombocytopenia after elective abdominal aortic aneurysm repair: a case report Guillaume Roberge1,2 · Tobias Tritschler1,3 · Caleb MacGillivray4 · Laurence Dufresne5 · Sudhir Kumar Nagpal5 · Dimitrios Scarvelis1
© Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Persisting heparin-induced thrombocytopenia (HIT) is characterized by ongoing thrombocytopenia more than 7 days after stopping heparin. It is part of cases referred to as autoimmune HIT (aHIT). In contrast to typical HIT cases, aHIT involves heparin-independent platelet activation mechanism highlighted by a strongly positive functional assay done without heparin. We report the first case of persisting HIT after an elective abdominal aortic aneurysm repair presenting with arterial and venous thrombosis, and describe the potential role of intravenous immunoglobulin in such patients. Keywords Case report · Heparin · Thrombocytopenia · Thrombosis · Immunoglobulin
Highlights • Ongoing thrombocytopenia more than 7 days after stop-
ping heparin and new thrombosis despite receiving treatment characterize persisting HIT. • Autoimmune HIT is characterized by a strongly positive functional assay done without heparin. • Intravenous immunoglobulin for treatment of autoimmune HIT results in improvement of thrombocytopenia and the most used dosing schedule is 1 g/kg daily for 2 doses.
* Guillaume Roberge [email protected] 1
Department of Medicine, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, ON, Canada
2
Department of General Internal Medicine, Centre Hospitalier Universitaire de Québec, Hôpital St-François d’Assise, Université Laval, Québec, QC, Canada
3
Department of General Internal Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
4
Clinical Epidemiology Program, Thrombosis Research Group, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, ON, Canada
5
Division of Vascular Surgery, The Ottawa Hospital, University of Ottawa, Ottawa, ON, Canada
• Intravenous immunoglobulin should be considered as an
emerging therapy for autoimmune HIT.
Introduction Heparin-induced thrombocytopenia (HIT) is an immunologic condition characterised by the association of venous and arterial thrombosis with thrombocytopenia classically in the context of heparin exposure [1]. HIT usually starts 5–10 days after initiation of heparin, in many cases after major surgery [2, 3]. The pathogenesis of HIT is complex and not completely understood. HIT is induced by pathologic IgG class antibodies recognizing macromolecular complexes formed by the cationic platelet factor 4 (PF4) and the polyanionic heparin. The immune complexes then activate platelets, endothelial cells and monocytes by binding to their Fcɣ specific receptors. The subsequent increase in thrombin generation explains the thrombotic processes seen in this pathology [4]. Over the past decade, it has been recognized that cases of particularly severe HIT involve
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