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79 Anticoagulant Therapy 3. Parenteral anticoagulants a. Heparin (unfractionated) 1. Platelet inhibitors...

79 Anticoagulant Therapy 3. Parenteral anticoagulants a. Heparin (unfractionated) 1. Platelet inhibitors ❖ Inhibits the active serine a. Aspirin- destroys cyclo-oxygenase to protease factors via Anti- inhibit r elease reaction thromhin ❖Affected platelets are inhibited ❖ Usually monitored with the permanently until replaced APTT using a heparin response b. Clopidogre1 (Plavix™)- Blocks the curve ADP recptor (P2Yl2) and is also ❖ Can also h e monitored using permanent until platelet is r eplaced anti-Xa assay c. Glycoprotein IIb/lIIa receptor b. Low Molecular Weight H eparin inhibitors (Ahciximah, (LMWH) Eptifibatide,Tirofiban)- not ! Targets Factor Xa permanent ❖ Yields a more predictable 2. Oral plasma protein anticoagu]ants response tha11 unfractionated a. Wafarin- prevents production of heparin functional Factors II, VII, IX and ❖ Does not usually require X by inhibiting Vitamin K. monitoring but if needed, ❖ requires monitoring using monitor with the anti factor Xa PT/INR assay. b. Thrombin inhibitor (Dabigatran)- requires no monitoring c. Factor Xa inhibitors (Rivaroxaban and Apixaban)- generally require no monitoring COAGULATION SAMPLE QUESTIONS I. If one pertorms an APTT on a patient on 4. A 22 year old female was seen in the high-dose warfarin therapy, we would emergency room with evidence of expect that the result would be: bleeding following a spider bite. A. Normal because warfarin effects the PT only Laboratory results show B. ,t. because of fibrinogen split Blood smear: Schistocytes products Platelet count: S0,000/mm3 C. l because of factor VII deficiency D. + because of other multiple factor PT: 20 secs APTT: 60 secs deficiencies d-dimer: positive 2. Abnormal PFA results and giant platelets The most likely diagnosis is best describe A. Allergic r eaction A. Bernard-Soulier syndrome B. Primary fihrinolysis B. Glanzmann thrombasthenia C. Secondary fihrinolysis C. von Willebrand disease D. Vitamin K deficiency D. Wiskott-Aldrich syndrome 5. A 4 year old male has a prolonged APTT of 3. A 7 year old male child is a candidate for 53 seconds. Mixing with normal plasma at ear tube surgery because of repeated ear a ratio of I to I yields an APTT of SO infections but he has a persistent seconds. Which of the following is most prolonged Prothrombin Time. The APTT is likely? normal. Which condition is most likely? A. Systemic 1upus erythematosu s A. Congenital factor VII deficiency B. Inhibitor or other anticoagulant B. Vitamin K deficiency C. Hemophilia B C. Hemophilia A D. Hemophilia A D. Factor V Leiden 80 ANSWERS AND RATIONALE 1. D 4. C The prothrombin time is used to monitor Option A is incorrect as allergies do not warfarin therapy, but warfarin results in. result in coagulation abnormalities. Option Bis deficiencies of Factors II, VII, IX, and X. The incorrect because schistocytes, decreased correct answer is D because Factors II, IX and X platelets and a positive D-dimer test are not seen are also measured by the APTT. in primary fibrinolysis. Option D is NOT char acterized by schistocytes and a positive D- 2. A dimer test. Options B and C are incorrect because 5. B platelet morphology is normal even though the bleeding time is prolonged. Option D is incorrect The 1 to 1 mix is still abnormal so the mixing because this syndrome is characterized by tiny study indicates a strong anticogulant or platelets and a prolonged bleeding time. inhibitor. Option A is incorrect since the patient might have a "lupus anticoagulant" but that does 3. B not mean he has systemic lupus erythematosus B is most likely because of the presentation. (SLE). A small number of patients with SLE The child is likely treated with repeated courses ex hibit the lupus anticoagulant but it is also of antibiotics which kills Vitamin K producing seen in many other conditions. Options C and organisms. Congenital deficiencies are extremely D are b oth incorrect since a 1: 1 mix would rare since inheritance is autosomal recessive. correct in either condition. Hemophilia A yields a normal PT and prolonged APTT and Factor V Leiden causes neither.