44 Thrombosis risk factors

Question 1

What are the causes of arterial thrombosis? (4).

Answer 1

Atherosclerosis.
Rupture of a atheromatous plaque.
Endothelial injury.
Platelet aggregation.

Question 2

What are the risk factors for arterial thrombi? (9).

Answer 2

Smoking.
Hypertension.
Hypercholesterolaemia.
Diabetes.
Family history.
Obesity.
Inactivity.
Age.
Male.

Question 3

Wat is the pathogenesis of venous thrombi? (2).

Answer 3

Venous stasis.

Hyper coagulable state.

Question 4

What are venous thrombi predominantly composed of?

Answer 4

Fibrin.

Question 5

What percentage of VTE are clinically silent?

Answer 5

80%

Question 6

What is post thrombotic syndrome?

Answer 6

Chronic leg symptoms after VTE damage.

Ulceration, redness, swelling.

Question 7

What proportion of VTE’s are hospital acquired?

Answer 7

2/3rds.

Question 8

What are the prophylactic strategies for VTE prevention?

Answer 8

Risk assessment on admission and repeat in 24 hours.

Small doses of blood thinners and compression stockings.

Question 9

What are the pharmacological methods of VTE prevention (5).

Answer 9

LMWH.
Fondaparinux.
Rivaroxaban.
Apixaban.
Dabigatran.

Question 10

What are the exclusion tests for VTE? (2).

Answer 10

Wells score.

D-dimers.

Question 11

What are D-dimers?

Answer 11

Cross-linked molecules produced when plasmin breaks down fibrin clots. Specific to fibrin break down.

Question 12

What are D-Dimers good at in VTE?

Answer 12

Good -ve predictive value.

Question 13

How are VTEs diagnosed?

Answer 13

D-dimer.
Ultrasound for DVT, CT scan for PE.
Possible VQ scan for PE.

Question 14

How is LMWH used in initiating VTE prevention?

Answer 14

Treat for at least five days AND overlap with warfarin until INR >2 for at least two consecutive days.

Question 15

Which novel anticoagulants have anti IIa mechanism?

Answer 15

Argatroban.

Bivalirudin.

Question 16

Contrast dose response for warfarin and new oral anticoagulants:

Answer 16

Warfarin: high dose variability.
NOACs: usually uniform.

Question 17

Define thrombophilia:

Answer 17

Familial or acquired disorder of heamostasis likely to predispose to thrombosis.
AND co-segregation with clinical thrombosis in pedigree.

Question 18

Simply define thrombophilia:

Answer 18

Patients who develop VTE:

spontaneously, of disproportionate severity, recurrently, or at an early age.

Question 19

What are the heritable thrombophilias? (6).

Answer 19

Antithrombin deficiency.
Protein C deficiency.
Protein S deficiency.
Activated Protein C resistance/FV Leiden.
Dysfibrinogenaemia.
Prothrombin 20210A.

Question 20

Name an acquired thrombophilia:

Answer 20

Antiphospholipid syndrome.

Question 21

What does antithrombin inhibit?

Answer 21

Xa.

Ia (thrombin).

Question 22

How does thrombin act as an anti-coagulant?

Answer 22

Binds to thrombomodulin on endothelial surface. Thrombin-thrombomodulin complex activates protein C, which degrades FVa and FVIIIa.

Question 23

What is factor V Leiden?

Answer 23

Activated protein C resistance.

Question 24

What is the risk of thrombosis in Factor V Leiden?

Answer 24

3-5x for heterozygote.

30-50x fo homozygote.

Question 25

What is the genetic basis of Factor V Leiden?

Answer 25

G to A at 1691.

Arg replaced by Gln at 506 amino acid.

Question 26

What is change in prothrombin 20210A?
Effect?
Who?

Answer 26

Point mutation in 3’ untranslated region of prothrombin gene.
Increased prothrombin levels.
Rare in Africa + Asia.

Question 27

What is antiphospholipid syndrome?

Answer 27

Antiphospholipid antibodies on at least 2 occasions 8 weeks apart with:
Venous or material thrombosis, or >2 foetal losses.