A nurse is caring for a client who has thrombophlebitis and is receiving a continuous infusion of heparin. The client asks the nurse how long it will take for the heparin to dissolve the clot. Which of the following responses should the nurse make?

Choice A rationale While pharmacodynamics can vary among individuals, this response fails to educate the client on the primary mechanism of action of heparin, which is its role as an anticoagulant. Heparin works by potentiating the action of antithrombin III, an enzyme that inactivates clotting factors like thrombin, thus preventing the formation and growth of new clots. Choice B rationale This response is factually incorrect regarding heparin's primary function. Thrombolytic agents, such as alteplase (tPA), are designed to dissolve established clots by activating plasminogen to plasmin, which breaks down the fibrin mesh. Heparin is an anticoagulant and does not directly lyse (dissolve) existing thrombi; it merely stops their growth. Choice C rationale This response is also scientifically inaccurate regarding heparin's action. Heparin's main therapeutic benefit in thrombophlebitis is preventing clot extension and subsequent embolization (movement) of the clot to other locations, such as the lungs (pulmonary embolism), by interfering with the coagulation cascade, not by actively breaking down the pre-existing clot mass. Choice D rationale Heparin is an anticoagulant, which functions by inhibiting the synthesis or activity of one or more coagulation factors, primarily by augmenting antithrombin III, thus preventing the formation of new clots and halting the growth of existing ones. Fibrinolytic or thrombolytic drugs are the agents that actually dissolve an established thrombus; therefore, this response is scientifically accurate.