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Last Updated: April 26, 2024

Claims for Patent: 6,010,911


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Summary for Patent: 6,010,911
Title: Apparatus for performing a heparin-independent high sensitivity platelet function evaluation technique
Abstract:An apparatus and method for performing activated clotting time tests, including their use for evaluating platelet functionality of a blood sample. The apparatus includes a plurality of test cells. Each of the cells comprises a heparin-inactivating agent, an anticoagulant agent, and a clotting reagent. At least one of the test cells further comprises a platelet activating agent. The clotting time is determined for each of the aliquot portions, and the relative clotting times of the aliquot portions in the cells are determinative of the platelet functionality of the sample. The method comprises the steps of combining a heparin-inactivating agent, an anticoagulant agent, a clotting reagent, a platelet activating agent, and the sample of blood to be tested to form a test mixture. The platelets of the sample are activated by agitating the test mixture, and the activated clotting time test is terminated upon detecting a predetermined change in a property of the test mixture. The activated clotting time of the sample of blood is calculated based on the elapsed time.
Inventor(s): Baugh; Robert F. (Parker, CO), Lane; Carole G. (Greenwood Village, CO), Wilson; Adrian C. (Denver, CO)
Assignee: Medtronic, Inc. (Minneapolis, MN)
Application Number:08/847,152
Patent Claims:1. An apparatus for performing a platelet functionality test on a blood sample, said apparatus comprising a plurality of test cells, each of said cells comprising a reaction chamber for receiving an aliquot portion of said sample, wherein each of said cells comprises a heparin-inactivating agent, an anticoagulant agent and a sufficient amount of a clotting reagent to achieve clotting, and wherein at least one of the cells comprises a platelet activating agent, wherein said platelet activating agent is a reagent other than said clotting reagent.

2. The apparatus as defined in claim 1, wherein the heparin-inactivating agent is an enzyme specific for heparin.

3. The apparatus as defined in claim 2, wherein the enzyme is heparinase.

4. The apparatus as defined in claim 1, wherein the heparin-inactivating agent is present at a concentration of between about 0.1. and about 10 international units per milliliter of blood sample.

5. The apparatus as defined in claim 1, wherein the heparin-inactivating agent is present at a concentration of between about 1.5 and about 2.5 international units per milliliter of blood sample.

6. The apparatus as defined in claim 1, wherein the heparin-inactivating agent is present at a concentration of between about 1.5 and about 2.5 international units per milliliter of blood sample.

7. The apparatus as defined in claim 1, wherein the anticoagulant agent is an inhibitor of at least one of Factor Xa and Factor II.

8. The apparatus as defined in claim 1, wherein the anticoagulant agent is a substrate-derived competitive thrombin inhibitor.

9. The apparatus as defined in claim 1, wherein the anticoagulant agent is a thrombin inhibitor selected from the group consisting of synthetic peptides, arginine derivatives, benzamidine derivatives, and lysine derivatives.

10. The apparatus as defined in claim 1, wherein the anticoagulant agent is argatroban.

11. The apparatus as defined in claim 1, wherein the anticoagulant agent is present at a concentration of between about 0.1 .mu.g and about 20 .mu.g per milliliter of blood sample.

12. The apparatus as defined in claim 1, wherein the anticoagulant agent is present at a concentration of between about 1 .mu.g and about 15 .mu.g per milliliter of blood sample.

13. The apparatus as defined in claim 1, wherein the anticoagulant agent is present at a concentration of between about 7 .mu.g and about 12 .mu.g per milliliter of blood sample.

14. The apparatus as defined in claim 1, wherein the clotting reagent is an activator of at least one of Factor XII and Factor XI.

15. The apparatus as defined in claim 1, wherein the clotting reagent is kaolin or diatomaceous earth.

16. The apparatus as defined in claim 1, wherein the clotting reagent is kaolin.

17. The apparatus as defined in claim 1, wherein the platelet activating agent is selected from the group consisting of 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine, arachidonic acid, collagen, epinephrine, and ristocetin.

18. The apparatus as defined in claim 1, wherein the platelet activating agent is 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine.

19. The apparatus as defined in claim 1, wherein the platelet activating agent in the blood sample is present at a concentration of between 0 and about 10 .mu.M.

20. The apparatus as defined in claim 1, wherein the platelet activating agent in the blood sample is present at a concentration of between 0 and about 1.0 .mu.M.

21. The apparatus as defined in claim 1, wherein the platelet activating agent in the blood sample is present at a concentration of between 0 and about 200 nM.

22. The apparatus as defined in claim 1, wherein the platelet functionality test is performed using a plunger sensor technique.

23. The apparatus as defined in claim 1, wherein the blood comprises a therapeutic amount of a platelet function inhibitor.

24. The apparatus as defined in claim 1, wherein the platelet function inhibitor is selected from the group consisting of Abciximab, 4-[4-[4-(aminoiminomethyl)phenyl]-1-piperazinyl]-1-piperidineacetic acid, hydrochloride trihydrate, and acetylsalicylic acid.

25. The apparatus as defined in claim 1, wherein the platelet function inhibitor is Abciximab, and wherein the platelet activating agent is 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine.

26. The apparatus as defined in claim 1, wherein the platelet function inhibitor is 4-[4-[4-(aminoiminomethyl)phenyl]-1-piperazinyl]-1-piperidincacetic acid, hydrochloride trihydrate, and wherein the platelet activating agent is 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine.

27. The apparatus as defined in claim 1, wherein the platelet function inhibitor is acetylsalicylic acid, and wherein the platelet activating agent is arachidonic acid.

28. An apparatus for performing a platelet functionality test on blood containing platelets using a plunger sensor technique, said apparatus comprising a cartridge having first and second test cells, each test cell containing a heparin-inactivating agent, an anticoagulant agent, and a sufficient amount of a clotting reagent to achieve clotting, and wherein said first test cell further comprises a platelet activating agent, wherein said platelet activating agent is a reagent other than said clotting reagent, and wherein a relative clotting time is determined for said first test cell as compared to said second test cell, and wherein the relative clotting time of said first cell is determinative of the platelet functionality of said blood.

29. The apparatus as defined in claim 28, wherein the heparin-inactivating agent is heparinase.

30. The apparatus as defined in claim 28, wherein the anticoagulant agent is a thrombin inhibitor selected from the group consisting of synthetic peptides, arginine derivatives, benzamidine derivatives and lysine derivatives.

31. The apparatus as defined in claim 28, wherein the anticoagulant agent is argatroban.

32. The apparatus as defined in claim 28, wherein the clotting reagent is kaolin.

33. The apparatus as defined in claim 28, wherein the platelet activating agent is 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine or arachidonic acid.

34. The apparatus as defined in claim 28, wherein the platelet activating agent is 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine.

35. The apparatus as defined in claim 29, wherein the heparinase is present at a concentration of between about 1.5 and about 2.5 units per milliliter of blood.

36. The apparatus as defined in claim 31, wherein the argatroban is present at a concentration of between about 7 .mu.g and about 12 .mu.g per milliliter of blood sample.

37. The apparatus as defined in claim 34, wherein the 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine in the blood is present at a concentration of between 0 and about 1.0 .mu.M.

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