Acute intraoperative HIT during heart surgery: Why so rare?

  • Theodore E. Warkentin
    Affiliations
    Department of Pathology and Molecular Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
    Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
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Published:September 12, 2016DOI:https://doi.org/10.1016/j.thromres.2016.09.005
      Cardiac and vascular surgery are almost always performed using intraoperative unfractionated heparin (UFH), with doses ranging from approximately 5000 units (vascular surgery) to tens of thousands of units (cardiac surgery utilizing cardiopulmonary bypass [CPB]). Moreover, many–if not most–cardiac or vascular surgery patients have previously received heparin, often recently, for such reasons as treating atherothrombosis (acute coronary ischemia, peripheral arterial disease), preventing thrombosis (congestive heart failure, atrial fibrillation), or even at preoperative diagnostic angiography. Since heparin exposure often triggers formation of antibodies against multimolecular complexes of platelet factor 4 (PF4) and heparin [
      • Linkins L.A.
      • Lee D.H.
      Frequency of heparin-induced thrombocytopenia.
      ], at least transiently, and since it is not standard practice to check for such anti-PF4/heparin antibodies prior to surgery, it is certain that each day there must be several patients around the world who receive intraoperative anticoagulation with heparin while harboring anti-PF4/heparin antibodies of varying levels of pathogenicity. Yet, to this editorialist's knowledge, until this issue of Thrombosis Research, there are no reports of adverse consequences related to acute intraoperative HIT during cardiac surgery.
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