Venous Thrombosis & Anticoagulants

Question 1

Describe how veins move blood back to the heart

Answer 1

Rely on muscles surrounding to pump the blood
Valves help to move blood towards the heart
Low pressure system - only activates the coagulation cascade

Question 2

State Virchow’s triad

Answer 2

Stasis
Hypercoagulation
Vessel wall

Question 3

How will a DVT present?

Answer 3

Hot, swollen, tender, pitting oedema

Question 4

How will a PE present?

Answer 4

Pulmonary infarction, pleuritic chest pain, collapse, hypoxia, right heart strain

Question 5

Name the risk factors for venous thrombosis

Answer 5

Age
Obesity 
Pregnancy & Puerperium 
Previous DVT/PE
Trauma/surgery 
Malignancy 
Paralysis 
Oestrogen therapy 
Infection 
Thrombophilia

Question 6

What is thrombophilia?

Answer 6

Inherited condition that increases the chances of having blood clots - increased fibrin clot formation and decreased anticoagulation

Question 7

What is factor V leiden?

Answer 7

Change in factor V meaning it is not switched off as efficiently as normal factor V

Question 8

Name the types of hereditary thrombophilia

Answer 8

Factor V leiden 
Prothrombin 20210 
Antithrombin deficiency 
Protein C deficiency 
Protein S deficiency

Question 9

What signs would increase you suspicious of hereditary thrombophilia?

Answer 9

Venous thrombosis <45 years old
Recurrent venous thrombosis
Unusual sites
Family history

Question 10

Describe the management for thrombophilia

Answer 10

Short term prophylaxis around events of known risk
Anticoagulation to treat thrombotic event
Long term anticoagulation if recurrent

Question 11

What signs would suggest long term anticoagulation is required?

Answer 11

History of previous thrombosis
Spontaneous thrombosis
Family history
Thrombophilia screening results

Question 12

What is the main cause of acquired thrombophilia?

Answer 12

Antiphospholipid antibody syndrome

Question 13

State the three main clinical features of anti-phospholipid antibody syndrome

Answer 13

Recurrent thrombosis
Recurrent foetal loss
Mild thrombocytopenia

Question 14

Describe the pathology in anti-phospholipid antibody syndrome

Answer 14

Antibodies bind to B2 glycoprotein 1 causing conformation change and activation of primary and secondary haemostasis

Question 15

What happens to APTT in anti-phospholipid antibody syndrome?

Answer 15

Prolong due to artefacts with assay - lupus anticoagulants

Question 16

What conditions are associated with anti-phospholipid antibody?

Answer 16

Autoimmune
Lymphoproliferative
Viral
Drugs

Question 17

How is anti-phospholipid antibody syndrome managed?

Answer 17

Aspirin - arterial

Warfarin - venous

Question 18

Name the two indications for anticoagulants

Answer 18

Venous thrombosis

AF

Question 19

What is the target of anticoagulants?

Answer 19

Fibrin clot

Coagulation cascade

Question 20

How does heparin work?

Answer 20

Potentiates antithrombin and has an immediate effect

Question 21

How is heparin administered?

Answer 21

IV or SC

Question 22

What are the two forms of heparin?

Answer 22

Unfractionated

Low molecular weight

Question 23

Describe the mechanism of action of heparin

Answer 23

Binds to antithrombin to keep it bound to thrombin/Xa leading to inactivation of coagulation

Question 24

What is the predominant action of the two forms of heparin?

Answer 24

Unfractionated - thrombin binding

LMWH - Xa binding

Question 25

How is heparin monitored?

Answer 25

APTT is sensitive for unfractionated | Anti-Xa assay can be used for LMWH

Question 26

What are the complications of heparin?

Answer 26

Bleeding Heparin induced thrombocytopenia Osteoporosis

Question 27

Describe heparin induced thrombocytopenia

Answer 27

Antibodies cause platelets to stick together (HITT)

Question 28

Which type of heparin is HITT more common in?

Answer 28

Unfractionated

Question 29

How do you reverse heparin?

Answer 29

Stop heparin | Protamine sulphate in severe bleeding

Question 30

How does protamine sulphate work?

Answer 30

Reverses antithrombin effect and complete reversal for unfractionated and partial for LMWH

Question 31

Name the coumarin anticoagulants

Answer 31

Warfarin, phenindione, acenocaoumarin, phenprocoumarin

Question 32

How do coumarin anticoagulants work?

Answer 32

Inhibition of vitamin K

Question 33

What depends on vitamin K?

Answer 33

Clotting factors II, VII, IX and X | Protein C and S

Question 34

What must be done at the start of warfarin therapy?

Answer 34

Heparin should be prescribed as initially increased risk of clot due to protein C and S decreased

Question 35

Describe the action of vitamin K

Answer 35

Carboxylation of glutamic acid residues allowing the clotting factors to bind to the platelet

Question 36

Why must warfarin be closely monitored?

Answer 36

Narrow therapeutic index

Question 37

How is warfarin monitored?

Answer 37

INR - mathematical correction using prothrombin time to allow for differences in lab techniques

Question 38

What is the INR aim for patients on warfarin?

Answer 38

2-3

Question 39

How can you reverse warfarin?

Answer 39

Stop therapy Oral vit K if INR >8 Administer clotting factors - blood components

Question 40

How long does vitamin K take to work in comparison to clotting factors?

Answer 40

Vit K - 6 hours | Clotting factors - immediate

Question 41

Name the two types of new anticoagulant

Answer 41

Oral direct thrombin inhibitor | Oral Xa inhibitor

Question 42

Give an example of an oral direct thrombin inhibitor and what is the problem with it?

Answer 42

Dabigatran | Excreted via kidneys and minor insult can lead to complications

Question 43

What are the Xa inhibitors?

Answer 43

Edoxaban, rivaroxaban, apixaban

Question 44

What are the indications for the new anticoagulants?

Answer 44

Prophylaxis DVT/PE Stroke prevention in AF