CCP Anticoagulation & Heparin Management 3 — Questions and Answers
Question 1: A patient develops heparin-induced thrombocytopenia type II (HIT II) prior to elective CABG. Which anticoagulant is most appropriate for CPB?
- Low molecular weight heparin (LMWH)
- Bivalirudin (Correct answer)
- Warfarin
- Fondaparinux
Correct answer: Bivalirudin
Bivalirudin is the preferred alternative anticoagulant for CPB in HIT II patients because it directly inhibits thrombin without cross-reactivity to heparin-PF4 antibodies.
Question 2: What is the primary disadvantage of using bivalirudin as an anticoagulant during CPB compared to unfractionated heparin?
- Inability to monitor anticoagulation effect
- No reversal agent is available (Correct answer)
- Shorter half-life requiring continuous infusion
- Increased risk of heparin-induced thrombocytopenia
Correct answer: No reversal agent is available
Unlike heparin, which can be reversed by protamine, there is no specific reversal agent for bivalirudin, which poses challenges if rapid anticoagulation reversal is needed.
Question 3: Which laboratory test is used to diagnose heparin-induced thrombocytopenia type II (HIT II)?
- Anti-Xa level
- Heparin-PF4 antibody assay (ELISA) and serotonin release assay (SRA) (Correct answer)
- Platelet aggregation study alone
- Fibrinogen level
Correct answer: Heparin-PF4 antibody assay (ELISA) and serotonin release assay (SRA)
HIT II diagnosis combines an immunological test (ELISA for heparin-PF4 antibodies) and a functional assay (SRA) to confirm platelet-activating antibodies.
Question 4: After CPB, a patient receives 350 mg of protamine to neutralize heparin. The ACT remains elevated at 180 seconds (baseline 120 s). What is the most appropriate next step?
- Administer additional protamine (Correct answer)
- Wait 10 minutes and recheck ACT
- Transfuse FFP to dilute excess heparin
- Administer aprotinin
Correct answer: Administer additional protamine
A persistently elevated post-protamine ACT suggests inadequate heparin reversal, and additional small doses of protamine (25–50 mg) should be administered.
Question 5: Which of the following best describes 'heparin rebound' after cardiac surgery?
- Re-elevation of ACT hours after protamine reversal due to heparin re-entering circulation from tissue depots (Correct answer)
- Acute platelet activation caused by residual heparin
- Recurrent AT III deficiency following protamine administration
- Thrombosis caused by excess protamine anticoagulant effect
Correct answer: Re-elevation of ACT hours after protamine reversal due to heparin re-entering circulation from tissue depots
Heparin rebound occurs when heparin sequestered in tissue depots re-enters the systemic circulation hours after protamine reversal, causing re-anticoagulation.
Question 6: During protamine administration for heparin reversal, the patient develops sudden hypotension and bronchospasm. What is the most likely cause?
- Heparin rebound
- Anaphylactic or anaphylactoid protamine reaction (Correct answer)
- Pulmonary embolism
- Air embolism from the CPB circuit
Correct answer: Anaphylactic or anaphylactoid protamine reaction
Protamine can trigger anaphylactic or anaphylactoid reactions, particularly in patients with fish allergies or prior protamine exposure (e.g., NPH insulin users).
Question 7: What effect does excess protamine have on coagulation?
- Enhances fibrinolysis
- Acts as an anticoagulant by inhibiting thrombin (Correct answer)
- Activates platelets causing thrombosis
- Increases factor XIII activity
Correct answer: Acts as an anticoagulant by inhibiting thrombin
Excess protamine itself has anticoagulant properties by directly inhibiting thrombin and platelet function, paradoxically worsening coagulopathy.
CCP Anticoagulation & Heparin Management 3
A patient develops heparin-induced thrombocytopenia type II (HIT II) prior to elective CABG.
Which anticoagulant is most appropriate for CPB?