Thrombotic Disorders

Question 1

General description of the clotting process?

Answer 1

• Formation of a primary clot by platelets
• Coagulation factor cascade activation
• Formation of a fibrin clot
• Triggering of fibrinolytic pathways

Question 2

When there is tissue damage what are the first steps towards clotting response?

Answer 2

• vasoconstriction at the damaged tissue
• Platelet adhesion (to subendothelial collagen)
• Platelet aggregation (via thromboxane released

Question 3

What is the function of thromboxane? When it is released?

Answer 3

Facilitates vasocontriction and platelet aggregation

It is secreted by activated platelets at the site of injury

Question 4

What factors convert plasminogen to plasmin? What is the effect of this?

Answer 4

Urokinase
TPA
Activated factor XII
Activated factor XI

Plasmin functions to degrade fibrin clots

Question 5

What is a thrombus? What is a thromboembolism?

Answer 5

Thrombus - blood clot

Thromboembolism - blood clot moving along a vessel

Question 6

What are the three main types of thrombosis?

Answer 6

Arterial

Venous

Microvasculature

Question 7

Describe the common composition of an arterial clot? What usually results as a complication of this?

Answer 7

White clot - Platelets and fibrin

Results in in ischaemia and infarction distal to the clot

Usually occurs secondary to atherosclerosis

Question 8

What are some risk factors for arterial thrombosis?

Answer 8

Age 
Smoking 
Sedentary lifestyle 
Hypertension 
Diabetes mellitus 
Obesity 
Hypercholesterolaemia

Question 9

What sort of treatments are available for arterial thrombosis?

Answer 9

Primary - lifestyle, treatment of vascular risk factors (hypertension, hypercholesterolaemia)

Acute - thrombolysis / antiplatelets or anticoagulants

Question 10

Describe the common composition of a venous clot? What usually results as a complication of this?

Answer 10

Red thrombus - fibrin and red cells

Results in back-flow pressure

Question 11

What causes arterial clots? What causes venous clots?

Answer 11

Arterial clots tend to occur secondary to atherosclerosis

Venous clots tend to occur due to stasis / hypercoagulability

Question 12

What are some risk factors for venous clots?

Answer 12

Age 
Pregnancy 
Surgery 
Obesity 
Hormonal therapy (COCP / HRT)
Tissue Trauma
Systemic Disease 
Family History 
Immobility

Question 13

What are some systemic conditions that may predispose patients to venous thrombosis?

Answer 13

Cancer

Myeloproliferative Neoplasm

Autoimmune disease (IBD / CT disease / antiphospholipid syndrome)

Question 14

How is venous thrombosis diagnosed?

Answer 14

Pretest probability scoring (wells / Geneva score)

Investigation: D-Dimer (fibrin breakdown product)

If probability high or D dimer positive then proceed to imaging

Question 15

What are some of the commonly used forms of imaging to diagnose venous thrombosis?

Answer 15

Doppler USS (for upper and lower limb veins)

Ventilation perfusion scan (PE)

CT pulmonary angiogram (PE)

Question 16

What are some treatment options for venous thrombosis?

Answer 16

Anticoagulants
(LMWH / warfarin / direct oral anticoagulants)

Thrombolysis (massive PE)

Question 17

What are some hereditary conditions that may predispose a person to venous thrombosis?

Answer 17

• Factor V leiden
• Prothrombin mutation
• Antithrombin deficiency
• Protein C deficiency
• Protein S deficiency

Question 18

Describe the pathophysiology of Factor V Leiden?

Answer 18

Resistance towards activated protein C results in the excessive production of thrombin

Hereditary disorder

Question 19

Which heritable thrombophilia diseases may be screened for?

Answer 19

People at risk of antithrombin deficiency may be screened

Because antithrombin deficiency causes highest likelihood of thrombogenicity due to antithrombins crucial role in thrombolytic processes

Question 20

Describe the common composition of a microvascular clot? What usually results as a complication of this?

Answer 20

Platelts and / or fibrin

Results in diffuse ischaemia at the affected area

Question 21

What tends to cause microvascular thrombosis? What are some risk factors?

Answer 21

Disseminated Intravascular Coagulation

• Diffuse systemic coagulation activation

Risk Factors: malignancy / septicaemia / eclampsia

Question 22

What can occur as a result of disseminated intravascular coagulation?

Answer 22

Activation of coagulation causing widespread fibrin deposition and thrombosis

Also excessive consumption of clotting factors leading to thrombocytopenia and coagulation factor deficiency, which can lead to bleeding

Can present with either a thrombotic or a heamorrhagic phenotype