44 Thrombosis risk factors Flashcards
What are the causes of arterial thrombosis? (4).
Atherosclerosis.
Rupture of a atheromatous plaque.
Endothelial injury.
Platelet aggregation.
What are the risk factors for arterial thrombi? (9).
Smoking. Hypertension. Hypercholesterolaemia. Diabetes. Family history. Obesity. Inactivity. Age. Male.
Wat is the pathogenesis of venous thrombi? (2).
Venous stasis.
Hyper coagulable state.
What are venous thrombi predominantly composed of?
Fibrin.
What percentage of VTE are clinically silent?
80%
What is post thrombotic syndrome?
Chronic leg symptoms after VTE damage.
Ulceration, redness, swelling.
What proportion of VTE’s are hospital acquired?
2/3rds.
What are the prophylactic strategies for VTE prevention?
Risk assessment on admission and repeat in 24 hours.
Small doses of blood thinners and compression stockings.
What are the pharmacological methods of VTE prevention (5).
LMWH. Fondaparinux. Rivaroxaban. Apixaban. Dabigatran.
What are the exclusion tests for VTE? (2).
Wells score.
D-dimers.
What are D-dimers?
Cross-linked molecules produced when plasmin breaks down fibrin clots. Specific to fibrin break down.
What are D-Dimers good at in VTE?
Good -ve predictive value.
How are VTEs diagnosed?
D-dimer.
Ultrasound for DVT, CT scan for PE.
Possible VQ scan for PE.
How is LMWH used in initiating VTE prevention?
Treat for at least five days AND overlap with warfarin until INR >2 for at least two consecutive days.
Which novel anticoagulants have anti IIa mechanism?
Argatroban.
Bivalirudin.
Contrast dose response for warfarin and new oral anticoagulants:
Warfarin: high dose variability.
NOACs: usually uniform.
Define thrombophilia:
Familial or acquired disorder of heamostasis likely to predispose to thrombosis.
AND co-segregation with clinical thrombosis in pedigree.
Simply define thrombophilia:
Patients who develop VTE:
spontaneously, of disproportionate severity, recurrently, or at an early age.
What are the heritable thrombophilias? (6).
Antithrombin deficiency. Protein C deficiency. Protein S deficiency. Activated Protein C resistance/FV Leiden. Dysfibrinogenaemia. Prothrombin 20210A.
Name an acquired thrombophilia:
Antiphospholipid syndrome.
What does antithrombin inhibit?
Xa.
Ia (thrombin).
How does thrombin act as an anti-coagulant?
Binds to thrombomodulin on endothelial surface. Thrombin-thrombomodulin complex activates protein C, which degrades FVa and FVIIIa.
What is factor V Leiden?
Activated protein C resistance.
What is the risk of thrombosis in Factor V Leiden?
3-5x for heterozygote.
30-50x fo homozygote.
What is the genetic basis of Factor V Leiden?
G to A at 1691.
Arg replaced by Gln at 506 amino acid.
What is change in prothrombin 20210A?
Effect?
Who?
Point mutation in 3’ untranslated region of prothrombin gene.
Increased prothrombin levels.
Rare in Africa + Asia.
What is antiphospholipid syndrome?
Antiphospholipid antibodies on at least 2 occasions 8 weeks apart with:
Venous or material thrombosis, or >2 foetal losses.
