Coagulation

Question 1

What is virchows triad?

Answer 1

Hypercoagulable blood,
Stasis/turbulence,
Endothelial injury

Question 2

Which clotting factors are key to the coagulation cascade?

Answer 2

II, V, VIII, IX, X

2, 5, 8, 9, 10

Question 3

Which 2 clotting factors form tenase and what is its purpose?

Answer 3

Tenase: IXa & VIIIa

Activates factor X (X => Xa)

Question 4

What forms prothrombinase and what is its purpose?

Answer 4

Prothrombin: Xa & Va
Activates factor II (II => IIa)
Prothrombin => thrombin

Question 5

What is the purpose of thrombin?

Answer 5

To convert fibrinogen to fibrin and allow formation fo a solid clot

Question 6

What is the difference between an arterial and venous thrombus?

Answer 6

Arterial = white thrombus (platelet rich)
Venous = red thrombus (red blood cell rich)

Question 7

What is the difference in treatment for arterial and venous thrombosis (give an example)?

Answer 7

Arterial = anti-platelet drugs (aspirin/clopidogrel)
Venous = anti-coagulant drugs (heparin/warfarin/apixiban)

Question 8

What effect does warfarin have upon the coagulation cascade?

Answer 8

Blocks modification of factor X and factor II

Question 9

How long does warfarin take to be active in the body?

Answer 9

2-3 days

Question 10

How long is the half life of warfarin and what does this mean in relation to preparation fro surgery?

Answer 10

Half life = 40 hours

Must be stopped a few days in advance of surgery to prevent risk of haemorrhage

Question 11

What is used if overdosed on warfarin?

Answer 11

Vit K

Question 12

What does heparin target?

Answer 12

Antithrombin III - increases rate of activity to counteract coagulation cascade (by thousands of times)

Question 13

What are the main anti-platelet drugs?

Answer 13

Aspirin, clopidogrel, ticegralor

Question 14

Name a fibrinolytic and its target

Answer 14

Streptokinase
tPA (tissue plasminogen activator):

Activates plasminogen so increases conversion to plasmin (plasmin breaks fibrin into fragments)