Thrombosis management Flashcards
What is the anticoagulant effects of heparin?
Binds to antithrombin and catalyses the inactivation of thrombin, IIa, Xa, IXa, XIa and XIIa
BInds to HCH and inactivates IIz
Binds factor IXa which inhibits factor X activiation
Mechanism of action of warfarin?
Vitamin K reductase inhibitor
–> Stops the reduction of Vitamin K –> stops carboxylation of factors II, VII, IX, X and XI
Oral anti-Xa inhibitors?
Rivaroxaban and Apixaban
Direct thrombin inhibitors?
Dabigatran
Evidence for NOACs?
Non inferior to warfarin
NOACs have better safety profile - less major bleeding
Highest risk of recurrence of VTE?
Unprovoked VTE
Long term anticoagulation after VTE?
For unprovoked VTE only
Long term warfarin or NOACs
If doesn’t want warfarin or NOAC = aspirin
Aspirin decreases risk of recurrent VTE by 30%
Thrombophilia testing after unprovoked VTE?
Most thrombophilias increase risk of a primary VTE but not recurrent VTEs
= Don’t test
What about lupus anticoagulant?
Increases risk of venous and arterial thrombosis
How to test for lupus anticoagulant?
Prolonged ApTT and DRVVT
ApTT not corrected with mixing test
Confirm test with dilute russel venom viper test - adding phospholipid will correct antibody
Also check for the presence of anti-cardiolipin antibody and Anti-beta2 GPI antibody
What should be checked for if patient diagnosed with splanchic vein thrombosis?
Prevalence of JAK2
What about IVC filters for preventing recurrence?
Nil mortality benefit
Increased mortality after 1 yr
Only for patients who can’t be anticoagulated safely
How do you measure the presence of Dabigatran?
ApTT and Thrombin clotting time very sensitive to the presence of dabigatran
If normal ApTT and thrombin clotting time = minimal or no drug
If normal ApTT and prolonged thrmbin clotting time = low drug levels
If both prolonged = significant drug levels
How do you measure the levels of dabigatran?
Haemaclot assay
How do you measure the presence of anti-Xa drugs
Modified Anti-Xa assay
Need to know what drug the patient is taking
How do you reverse Dabigatran
Idaracizimab
2.5gm bolus and repeated at 15 minutes
Works within 1 minute
Monoclonal antibody which has a greater binding affinity for dabigatran than thrombin –> neutralizes activity
How to reverse rivaroxaban and apixaban?
Adexenate
Decoy Xa without anticoagulant activity
BInds drugs –> neutralizes activity
Can NOACs be used for prosthetic heart valve prophylaxis?
NO
Which side is a pregnant woman more likely to get a DVT?
Left side
Due to anatomy of the vessels
Does screening for cancer in unprovoked VVTE improve outcomes?
10% of patients with unprovoked VTE have cancer at 12-24 months
SOME study = no difference in time to diagnosis, mortality from cancer or reduction in recurrent VTEs with extensive screening - targeted hx and ex and ix same outcomes
Do males or females have a higher risk of recurrence of VTE?
Males
