A 58-year-old man presents with chest pain and dyspnea. Vital signs: BP 128/82 mmHg, HR 102/min, RR 18/min, temp 37.2°C, SpO2 98% on room air. He receives aspirin, clopidogrel, and unfractionated heparin for suspected acute coronary syndrome. Two hours later, aPTT is 95 seconds (normal 25-35 sec), troponin is elevated at 2.8 ng/mL, and ECG shows ST-segment depression. No bleeding noted. Which drug explains the prolonged aPTT?
- A)Aspirin acetylates platelet cyclooxygenase, directly inhibiting thrombin generation
- B)All three drugs synergistically inhibit factor II, V, VII, and X
- C)Heparin directly degrades fibrinogen into fibrin degradation products
- D)Unfractionated heparin inactivates thrombin and factor Xa by enhancing antithrombin III activityGABARITO
- E)Clopidogrel irreversibly inhibits platelet ADP receptors, preventing factor activation
Explicação
Unfractionated heparin is a parenteral anticoagulant that enhances antithrombin III activity, which then inactivates thrombin (factor IIa) and factor Xa. This directly prolongs the aPTT. The elevated aPTT reflects therapeutic anticoagulation for acute coronary... Ver explicação completa e trilha adaptativa →