Clinical Haemostasis and Thrombosis

Question 1

what is primary homeostasis and what is required to form this?

Answer 1

It is the formation of an UNSTABLE PLATELET PLUG.

Von willebrand factor and collagen are required.

Question 2

What clinical feature is common to all bleeding disorders?

Answer 2

Easy bruising

Question 3

A disease of primary haemostasis could affect what components of the unstable platelet plug?

Answer 3

Vessel wall - ageing and steroids can damage the endothelium
Von Willebrand factor - vWF disease means that you have no vWF
Platelets - warfarin and other drugs affect platelet activity.
Thrombocytopenia (decrease in the number of platelets in the blood)

Question 4

What is a characteristic feature of thrombocytopenia?

Answer 4

Petechiae ( these are small spots which occur in people)

Question 5

what are the defects of primary homeostasis?

Answer 5

• Immediate
• easy bruising
• Nosebleeds
• Gum bleeding
• Menorrhagia
• Bleeding after trauma/surgery
• Petechiae

Question 6

What is the main role of secondary homeostasis?

Answer 6

1. involves the generation of thrombin from prothrombin

2. Thrombin converts fibrinogen to fibrin which form the insoluble mesh around the platelets.

Question 7

What do we use to visualise the process of coagulation?

Answer 7

-we can visualise by measuring thrombin generation over time- this is called thrombogram.

Question 8

Why is there a lag between the administration of a tissue factor trigger and the thrombin burst?

Answer 8

This is when co-factors and clotting factors are synthesised. This is when the co-factors and anticoagulant enzymes are being generated then there is a burst of thrombin.

Question 9

what happens in haemophilia?

Answer 9

In haemophilia, coagulation factor 8 is missing causing failure of the thrombin burst. There is a much slower increase in thrombin and not as much thrombin is produced, this means that you do not get much of a fibrin mesh formed so the clot does NOT become stabilised.

Question 10

what are the defects of secondary heamostasis?

Answer 10

Deficiency or defect of coagulation Factor 1-13.

e. g.
- haemophilia co factors 8 or 9.
- Liver disease (most coagulation factors are made in the liver)
- Drugs (warfarin- inhibits synthesis of coagulation factors)
- Dilution (results from volume replacement)
- Consumption (disseminated intravascular coagulation-acquired)

Question 11

What is haemophilia defined as?

Answer 11

Failure to generate fibrin to stabilise the platelet plug

Question 12

Describe the pattern of bleeding of defects in secondary haemostasis.

Answer 12

DELAYED - people with defects in secondary haemostasis are generally fine with small cuts. They bleed deeper into joints and muscles. Do NOT tend to bleed excessively from small cuts (because the primary haemostasis is fine)

Question 13

What is the hallmark of haemophilia?

Answer 13

Haemarthrosis - bleeding into joints. This is a characteristic feature of severe haemophilia A and B. They bleed into joints and the pressure builds up and the joint becomes swollen and painful.

Question 14

State some defects of clot stability.

Answer 14

Excess fibrinolytic (tPA)
Deficient antifibrinolytic (antiplasmin)

Question 15

What is DIC?

Answer 15

Disseminated intravascular coagulation - widespread activation of the coagulation cascade
Leads to consumption of the clotting factors - that’s why it’s also called consumptive coagulopathy

Question 16

what are the clinical features of secondary heamostasis?

Answer 16

• often delayed
• -prolonged
• Deeper: joints and muscles
• Do not tend to get excessive bleeding from small cuts
• small vessels are generally ok
• Nosebleeds are rare
• bleeding after trauma/surgery
• bleeding after intramuscular injections

Question 17

what does venous emboli and arterial emboli cause?

Answer 17

Venous emboli= Pulmonary embolism

Arterial embolism= usually from heart, may cause stroke or limb ischaemia.

Question 18

What are the consequences of thromboembolism?

Answer 18

Thrombophlebitic syndrome= swelling and ulcers in the leg due to damage to valves leading to stasis.
Pulmonary hypertension

Question 19

what can increase the irsk of thrombosis?

Answer 19

• inflammatory disorder
• pregnancy
• combined contraceptive pill

Question 20

How does risk of thrombosis change with age?

Answer 20

Increases

Question 21

What are the three components of Virchow’s triad?

Answer 21

Hypercoagulability= dominant in venous thrombosis
Vessel wall injury = dominant in arterial thrombosis
Stasis= complex, contributes to both. the fater the blood flows, the more activated coagulation factors get swept away and the less chance of a thrombus forming

Question 22

Why is pregnancy associated with an increase in the risk of thrombosis?
.

Answer 22

Pregnancy involved reduced mobility and reduced flow and a decrease in protein S meaning that blood becomes procoagulant

Question 23

What is the only circumstance in which thrombolytic therapy is given? Why is it not given more often?

Answer 23

STROKE

Because giving thrombolytic therapy increases the risk of bleeding.

Question 24

What happens in haemophilia?

Answer 24

Deficiency of factor 8 or factor 9. Massively slows down the production of thrombin and so there is no real thrombin burst. Not much fibrin mesh is formed and so the clot is not stabilised.

Question 25

What is abnormal bleeding?

Answer 25

Abnormal bleeding is characterised by being spontaneous, prolonged or out of proportion to the injury.

Question 26

what is thrombosis

Answer 26

Thrombosis is inappropriate clot formation and occurs in an intact vessel

Question 27

what type of embolism do most patients die from?

Answer 27

Venous thromboembolism is an important cause of death in hospital patients

Question 28

what should patients who are at increased risk receive?

Answer 28

should receive anticoagulant therapy as thromboprophylaxis