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A 65-year-old woman is admitted to the ICU after coronary bypass surgery for acute myocardial infarction with cardiogenic shock. The postoperative course is complicated by acute renal insufficiency, and on postoperative day 5 the patient develops acute dyspnea with hypoxemia. A diagnosis of left lower extremity deep venous thrombosis is made by lower extremity ultrasonography, with probable pulmonary embolism. The patient is started on IV unfractionated heparin (weight-based nomogram) to achieve a partial thromboplastin time (PTT) 1.5 to 2 times the normal value.
Laboratory studies at this time reveal normal electrolyte levels, a blood urea nitrogen level of 45 mg/dL, creatinine level of 2.8 mg/dL, WBC count of 9,000/µL, hemoglobin level of 10.1 g/dL, platelet count of 250,000/µL, and normal prothrombin time, international normalized ratio, and partial thromboplastin time. After 2 days of therapeutic anticoagulation with unfractionated heparin, the patient reports right lower extremity pain. Examination of the right lower extremity reveals a cold, painful extremity with loss of distal pulses. Laboratory studies reveal a blood urea nitrogen level of 50 mg/dL, creatinine level of 2.8 mg/dL, platelet count of 90,000/µL, international normalized ratio of 1.2, and PTT of 50 seconds. Which of the following therapeutic options is most appropriate at this time?
A. Increase unfractionated heparin to achieve a higher PTT.
B. Discontinue unfractionated heparin and start enoxaparin.
C. Discontinue unfractionated heparin and start warfarin.
D. Discontinue unfractionated heparin and start argatroban.
E. Discontinue anticoagulation.
What is D. Discontinue unfractionated heparin and start argatroban.