Venous thrombosis

Question 1

Describe the characteristics of venous thrombosis?

Answer 1

low pressure system
platelets not activated
activated coagulation cascade so clots rich in fibrin

Question 2

How do you treat venous thrombosis? (3)

Answer 2

heparin
Warfarin
new oral anticoagulants
these interfere with secondary haemostasis

Question 3

clinical signs of:

• DVT?
• PE?

Answer 3

-limb feels hot, swollen, tender
pitting oedema

-Pulmonary infarction causing pleuritic chest pain
CV collapse and death
hypoxia
R heart strain

Question 4

What are the risk factors for venous thromboembolism?

-what is hypercoagulability associated with?

Answer 4

changes in: stasis, vessel wall, hypercoaguability

Age
Marked obesity
Pregnancy
puerperium
Oestrogen therapy
Previous DVT/PE
Trauma/surgery
malignancy 
Paralysis
Infection
Thrombophilia

-release of tissue factor, raised vWF and factor VIII

Question 5

Thrombophilia

• what is it?
• give the potential mechanisms by which this occurs?

Answer 5

-familial or acquired disorders of the haemostatic mechanism which are likely to predispose to thrombosis

-inc coagulation activity: platelet plug formation and fibrin clot formation
Dec fibrinolytic activity
Dec anticoagulant activity (most common) e.g. deficiency in antithrombin protein C & protein S

Question 6

Hereditary thrombophilias

• what are they?
• name 5
• when should screening be considered?
• management

Answer 6

-group of genetic defects in which affected individuals have an inc tendency codevelop premature, unusual and recurrent thromboses

-Factoe V Leiden
Prothrombin 20210 mutation
antithrombin deficiency 
protein C deficiency 
Protein S deficiency 
*dont increase risk of venous thrombosis*

-VT <45 
recurrent VT
unusual VT
Fam hx of venous thrombosis
Fam hx of thrombophilia 

-advice on avoiding risk
short term prophylaxis
short term anticoagulation
long term anticoagulation if recurrent events

Question 7

How do you asses the need for long term anticoagulation?

• first episode?
• second?
• how do you asses risk of recurrent thrombosis?

Answer 7

Risk of recurrent thrombosis balanced with
Risk of serious haemorrhage

• anticoagulate for 6 months
• lifelong anticoagulation

-Hx prev thrombosis
spontaneous= greater risk than acquired
family hx
Thrombophilia screen

Question 8

Acquired thrombophilia: antiphospholipid antibody syndrome

• features?
• describe the pathogenesis?
• name the antibodies involved and their effect on the APTT?
• associated with which conditions?
• treatment?

Answer 8

-recurrent thromboses at young age
Arterial & venous
recurrent foetal loss
Mild thrombocytopenia

• antibodies lead to conformational change in Bets 2 glycoprotein 1 which leads to activation of both primary and secondary haemostasis and vessel wall abnormalities
• autoantibodies with specificity for anionic phospholipids and which prolong phospholipid dependant coagulation tests in vitro- lupus anticoagulants
• Autoimmune, Lymphoproliferative disorders, Viral infections, drugs, primary

-Give treatment depending on thrombotic events
Aspirin- arterial
warfarin- venous