Inherited and Acquired Thrombotic Disorders

Question 1

What is the link between DVT and PE?

Answer 1

• Most above knee DVTs embolise

Question 2

What 2 factors are most important in venous thrombosis?

Answer 2

• Stasis

- Hypercoaguability

Question 3

What factor are most important in arterial thrombosis?

Answer 3

• Vessel wall damage (atherosclerosis)

Question 4

Comparison between Arterial Thrombosis and Venous Thrombosis

Answer 4

=> Arterial Thrombosis:

• Platelet based so formation of white thrombus
• Primary trigger is rupture of atherosclerotic plaque
• Involves rupture of endothelium and release of constituents of plaque

=> Venous Thrombosis:

• Fibrin based so formation of red thrombus
• Endothelium remains intact but is converted from anti-coagulant surface to pro-coagulant surface

Question 5

What is thrombophilia?

Answer 5

Abnormality in blood coagulation that increases risk of thrombosis

Question 6

What are some examples of Inherited Thrombophilias?

Answer 6

• Factor V Leiden (most common)
• Prothrombin mutation (second most common)
• Protein C deficiency
• Protein S deficiency
• Antithrombin deficiency
• High factor VIII levels
• Hyperhomocysinaemia

Question 7

What is the pathophysiology of Factor V Leiden?

Answer 7

• Point mutation
• Normally, activated protein C is responsible for the inhibition of factor V
• In Factor V Leiden, activated protein C resistance means activated protein C no longer binds to factor V, leading to an increase in fibrin production

Question 8

Thrombosis increases with age. What are the strongest risk factors with increasing age?

Answer 8

• Decreased mobility
• Reduced muscular tone
• Enhancing disease
• Ageing tissue

Question 9

What is the link between thrombosis and the Combined Oral Contraceptive Pill?

Answer 9

=> COCP increases the risk of thrombosis through:

• an acquired increase in resistance to APC
• reduction in protein S levels
• reduction in antithrombin levels

Question 10

What is the link between HRT and venous thromboembolism?

Answer 10

• Increases risk
• Risk if highest shortly after starting
• Irrespective of type or mode of HRT

Question 11

What are the investigations in suspected Thrombophilia/?

Answer 11

=> Inherited Thrombophilia testing

=> Protein C and Protein S levels

=> Antithrombin levels

=> Mutation Analysis