What is the role of protamine in the cath lab?

• A. Reverses platelet aggregation.
• B. Reverses warfarin.
• C. A vasodilator for radial spasm.
• D. Reverses unfractionated heparin to help achieve hemostasis after sheath removal or reversal of anticoagulation.

Answer: (D)

Protamine’s role in the cath lab is to reverse unfractionated heparin so you can achieve hemostasis after the sheath is removed. Heparin is given during catheter-based procedures to prevent clotting, and once the intervention is done you want to stop that anticoagulant effect to minimize bleeding. Protamine, a positively charged protein, binds to the negatively charged heparin and forms a stable complex, neutralizing its anticoagulant action. The typical dose is about 1 mg of protamine for every 100 units of heparin given, with adjustments based on timing and residual heparin activity. This reversal specifically targets unfractionated heparin; low-molecular-weight heparin is only partially reversed and warfarin reversal requires vitamin K or other agents, not protamine. Protamine is not a vasodilator and does not reverse platelet aggregation. You do need to monitor for potential adverse reactions, such as hypotension or allergic responses, especially in patients with fish allergies or prior protamine exposure, and administer it carefully rather than as a rapid bolus.