Antibodies v. factor 4 platelets complexes
10 x more common with heparin than with LMWH
20-50 percent get arterial or venous thrombosis
platelet count is less than fifty percent normal
may use a direct thrombin inhibitor eg. argabotran
basic science notes
heparin and LMWH are indirect thrombin inhibitors as they do not act on fibrin bound thrombin. By contrast, the direct inhibitors (hirudin, argabotran, bivalirudin) inactivate fibrin bound thrombin.
At an injury site, F VIIa (extrinsic pathway) and tissue factor are activated. Thrombus propagates when F IXa binds to cofactor VIIIa (intrinsic pathway) and forms a complex that binds F X. Xa binds Va to form prothrombinase that converts prothrombin to thrombin. XI promotes Xa, final step is conversion of fibrinogen to fibrin
10 x more common with heparin than with LMWH
20-50 percent get arterial or venous thrombosis
platelet count is less than fifty percent normal
may use a direct thrombin inhibitor eg. argabotran
basic science notes
heparin and LMWH are indirect thrombin inhibitors as they do not act on fibrin bound thrombin. By contrast, the direct inhibitors (hirudin, argabotran, bivalirudin) inactivate fibrin bound thrombin.
At an injury site, F VIIa (extrinsic pathway) and tissue factor are activated. Thrombus propagates when F IXa binds to cofactor VIIIa (intrinsic pathway) and forms a complex that binds F X. Xa binds Va to form prothrombinase that converts prothrombin to thrombin. XI promotes Xa, final step is conversion of fibrinogen to fibrin
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