Answer:
Option A, heparin
Explanation:
Activated partial thromboplastin time (aPTT) is the measure of how long it takes for the blood to coagulate, or clot, typically measure in seconds. The expected range for aPTT is 25 to 35 seconds. Times quicker than this can indicate that the blood is clotting faster than normal, such as in patients with thrombophilia or early disseminated intravascular coagulation (DIC). Times slower than this can indicate that the blood is not clotting as fast as it should.
Heparin is an anticoagulant medication that works by inhibiting factor Xa and thrombin from forming clot formations. The idea is that in doing so, the medication will prevent further clots from developing while the body's normal processes breakdown the clots currently present within the blood vessels.
Because of this direct relationship with clotting ability, aPTT is used to monitor its therapies. If the aPTT is too high, meaning it takes much too long for the blood to form clots, this can indicate the dose of heparin is too high. Vice versa is also true; aPTT too low, heparin may need boosted.
Thus, option A, is the correct choice.
Why Not Other Options:
Aspirin has antiplatelet properties which, in turn, can help with preventing clot formations, but this is not the primary purpose of this medication nor is this test directed at monitoring its effectiveness.
Alteplase (t-PA) is a thrombolytic medication aimed at breaking down current clots rather than preventing clot formations altogether. So aPTT may not reflect its efficacy as well as this test would for heparin.
Lastly, dabigatran is a thrombin inhibitor anticoagulant medication that employs the use of aPTT to monitor anticoagulation activity, but this test becomes less reliable with higher doses of medication administered.