Arterial and Venous Thrombosis

Question 1

Arterial thromboses most commonly affect which circulations?

Answer 1

Coronary
Cerebral
Peripheral

Question 2

Why do plaques not rupture in venous thrombosis?

Answer 2

As it is a low pressure system

Question 3

Which is activated in venous thrombosis - the coagulation cascade or platelet plug?

Answer 3

Coagulation cascade

Question 4

What is Virchow’s triad of venous thrombosis?

Answer 4

Stasis
Vessel wall damage
Hypercoaguability

Question 5

Give some risk factors for venous thrombo-embolism

Answer 5

Age
Obesity
Pregnancy
Puerperium
Oestrogen therapy
Previous DVT/PT
Trauma
Malignancy
Paralysis
Infection
Thrombophilia

Question 6

What is thrombophilia?

Answer 6

A disorder of the haemostatic mechanism predisposing an individual to thrombosis

Question 7

What are the broad causes of thrombophilia?

Answer 7

Increased coagulation activity
Decreased fibrinolytic activity
Decreased anticoagulant activity

Question 8

What naturally occurring anticoagulants are found in the blood?

Answer 8

Anti-thrombin

Protein C and protein S

Question 9

Give some examples of hereditary thrombophilias

Answer 9

Factor V Leiden
Prothrombin 20210 mutation
Antithrombin/protein C/protein S deficiencies

Question 10

How is hereditary thrombophilia managed?

Answer 10

Short term prophylaxis (during periods of known risk)
Short term anticoagulation (treat events)
Long term anticoagulation (recurrent events)

Question 11

What is the main cause of acquired thrombophilia?

Answer 11

Anti-phospholipid syndrome

Question 12

Give some features of anti-phospholipid syndrome

Answer 12

Recurrent thromboses (either arterial/venous)
Recurrent fetal loss
Mild thrombocytopenia

Question 13

What is the pathogenesis of anti-phospholipid syndrome?

Answer 13

Antibodies causes a change in beta 2 glycoprotein 1 causing activation of primary and secodary haemostasis

Question 14

Patients with antiphospholipid syndrome will have a prolonged PT/APTT

Answer 14

APTT

Question 15

What is the main risk factor for an arterial thrombosis?

Answer 15

Atherosclerosis

Question 16

What occurs in atherosclerosis?

Answer 16

Damage to the endothelium causes recruitment of cholesterol-rich macrophages that form plaques

Question 17

What occurs when atherosclerotic plaques rupture?

Answer 17

Platelets adhere to the plaque and become activated recruiting more platelets to form a plug

Question 18

What are the main risk factors for arterial thrombosis?

Answer 18

Hypertension
Smoking
High cholesterol
Diabetes mellitus

Question 19

What allows platelets to bind to subendothelial collagen?

Answer 19

Glycoprotein 1b

von Willebrand factor

Question 20

What allows platelets to attach to each other?

Answer 20

Glycoproteins IIb and IIIa

Fibrinogen

Question 21

Why do platelets alter their shape to stabilise the clot?

Answer 21

To expose more phospholipid on the surface and provide a greater surface area for coagulation

Question 22

What granules are released by platelets to further stimulate platelet activation?

Answer 22

Thrombin
Thromboxane A2
ADP

Question 23

How does aspirin work?

Answer 23

Inhibits cyclo-oxygenase preventing production of thromboxane A2

Question 24

What are the main side effects of aspirin?

Answer 24

Bleeding
GI ulceration (due to blocking of prostaglandins)

Question 25

What drugs act as ADP receptor antagonists?

Answer 25

Clopidogrel

Prasugrel

Question 26

How do clopidogrel and prasugrel work?

Answer 26

They bind to the P2Y12 receptor meaning ADP cannot bind to it and stimulate platelet aggregation

Question 27

What drug acts as a glycoprotein IIb/IIIa inhibitor?

Answer 27

Abciximab

Question 28

For how long do anti-platelet drugs affect platelet function?

Answer 28

7-10 days