Defining heparin resistance: communication from the ISTH SSC Subcommittee of Perioperative and Critical Care Thrombosis and Hemostasis.


The term heparin resistance (HR) is used by clinicians without specific criteria. We performed a literature search and surveyed our SSC membership to better define the term when applied to medical and intensive care unit patients. The most common heparin dosing strategy reported in the literature (53%) and by survey respondents (80.4%) was the use of weight-based dosing. Heparin monitoring results were similar based on the proportion of publications and respondents that reported the use of anti-Xa and activated partial thromboplastin time. The most common literature definition of HR was >35 000 U/d, but no consensus was reported among survey respondents regarding weight-based and the total dose of heparin when determining resistance. Respondent consensus on treating HR included antithrombin supplementation, direct thrombin inhibitors, or administering more heparin as the strategies available for treating HR. A range of definitions for HR exist. Given the common use of heparin weight-based dosing, future publications employing the term HR should include weight-based definitions, monitoring assay, and target level used. Further work is needed to develop a consensus for defining HR.





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Publication Info

Levy, Jerrold H, Roman M Sniecinski, Bianca Rocca, Kamrouz Ghadimi, James Douketis, Corinne Frere, Julie Helms, Toshiaki Iba, et al. (2023). Defining heparin resistance: communication from the ISTH SSC Subcommittee of Perioperative and Critical Care Thrombosis and Hemostasis. Journal of thrombosis and haemostasis : JTH, 21(12). pp. 3649–3657. 10.1016/j.jtha.2023.08.013 Retrieved from

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Kamrouz Ghadimi

Associate Professor of Anesthesiology

Dr. Ghadimi is a cardiothoracic anesthesiologist, intensivist (ICU doctor), researcher, educator, and director of the clinical research unit in the Department of Anesthesiology at Duke Health. He has published over 100 peer-reviewed manuscripts, book chapters, online reviews, and editorials. His expertise involves the perioperative and intensive care management of patients undergoing cardiac and noncardiac surgery, with a special focus on the treatment of bleeding and inflammation related to shock and mechanical circulatory support and on the modification of pulmonary circulation to optimize end-organ blood flow.

Clinical Education
Dr. Ghadimi is a medical school graduate of Boston University School of Medicine, completed his internship in general surgery at the University of California Irvine Medical Center and Long Beach Veterans Affairs Medical Center and completed clinical anesthesiology residency at the Allegheny Health Network in Pittsburgh, Pennsylvania. He completed advanced clinical fellowship specialization in adult Critical Care Medicine (surgical focus) and Cardiothoracic Anesthesiology at the University of Pennsylvania Health System in Philadelphia, Pennsylvania. 

Dr. Ghadimi's expertise and instruction spans across the cardiothoracic operating rooms and cardiothoracic surgical ICU environments. His expertise includes perioperative hemostasis & thrombosis, critical care of the heart or lung transplant recipient, and critical care for the patient on mechanical circulatory support, which may include extracorporeal life support (ECMO) or ventricular assist devices/systems.

Research Education
Dr. Ghadimi is a clinical and translational researcher and holds a Master in Health Sciences (M.H.Sc.) from the Duke-NIH Clinical Research Training Program. 

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