Q: 64 year old male with End Stage Renal disease (on hemodialysis) presented to Emergency Room (ER) with chest pain and found to have unstable angina. Patient is known to cardiology service from previous 'cath' three months ago and was advised to go through bypass surgery but he opted for medical management. Now patient is agreeable for surgery. Review of his record showed that 3 months  ago while in hospital, he was tested positive for Heparin Induced Thrombocytopenia (HIT). His platelet counts are now normal, but to prepare him for surgery, his HIT panel was send again and found to be stayed positive. All of the following can be used in operation theater (OR) except?

A) preemptive  transfusion of platelets
B) Bivalirudin
C) Heparin reexposure but with intravenous Epoprostenol
D) Plasma exchange upon initiation of cardiopulmonary bypass (CPB)
E) Argatroban


Answer: A

Objective of above question is to highlight a less known option, epoprostenol. Epoprostenol is a prostaglandin PGI2 which can be used if heparin is used in a patient with positive HIT panel. Though bivalirudin or Argatroban can be used in this scenario but a surgeon may choose against them due to their inability to reverse the anticoagulant effect at the conclusion of cardiopulmonary bypass (CPB). Another viable option is plasma exchange upon initiation of CPB to reduce the titer of HIT antibodies prior to heparin exposure.

Epoprostenol potently desensitizes platelets during exposure to heparin by inhibiting platelet activation and by increasing intracellular concentrations of platelet cyclic adenosine monophosphate. It is given as an intravenous infusion while CPB runs and till protamine is administered to reverse heparin effect. Pharmacy service should be consulted for protocolized infusion of  epoprostenol. The most common side effect is vasoplegia.

Choices A is not a recommended option.



References:

1. Welsby IJ, Um J, Milano CA, et al. Plasmapheresis and heparin reexposure as a management strategy for cardiac surgical patients with heparin-induced thrombocytopenia. Anesth Analg 2010; 110:30.

2.  Koster A, Dyke CM, Aldea G, et al. Bivalirudin during cardiopulmonary bypass in patients with previous or acute heparin-induced thrombocytopenia and heparin antibodies: results of the CHOOSE-ON trial. Ann Thorac Surg 2007; 83:572.

3. Aouifi A, Blanc P, Piriou V, et al. Cardiac surgery with cardiopulmonary bypass in patients with type II heparin-induced thrombocytopenia. Ann Thorac Surg 2001; 71:678.

4. Mertzlufft F, Kuppe H, Koster A. Management of urgent high-risk cardiopulmonary bypass in patients with heparin-induced thrombocytopenia type II and coexisting disorders of renal function: use of heparin and epoprostenol combined with on-line monitoring of platelet function. J Cardiothorac Vasc Anesth 2000; 14:304. 

5. Warkentin TE, Greinacher A. Heparin-induced thrombocytopenia and cardiac surgery. Ann Thorac Surg 2003; 76:2121. 

6. Argatroban pharmacokinetics and pharmacodynamics in critically ill cardiac surgical patients with suspected heparin-induced thrombocytopenia. Thromb Haemost 2016; 115:1081.