Final answer:
The abbreviation for activated partial thromboplastin time is PTT, a test used to measure blood clotting time and important in the context of thrombolytic therapy.
Step-by-step explanation:
The abbreviation for activated partial thromboplastin time is PTT. This test measures how long it takes for a person's blood to clot and can be used to assess coagulation disorders. In the context of thrombolytic therapy, which involves drugs like tissue plasminogen activator that convert plasminogen to plasmin and break down clots, monitoring coagulation times like PTT is crucial to ensure patient safety and treatment efficacy.