Week 3- arterial thrombosis and anti-platelet drugs Flashcards

1
Q

Is atherosclerosis the same as arterial thrombosis?

What is atherosclerosis?

A

No they are not the same.
Damage to endothelium causes recruitment of macrophages, they eat the cholesterol forming ‘foamy macrophages’
This forms plaques rich in cholesterol.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

when is an atherosclerotic plaque stable?

A

When it is hylanised and calcified.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

In what conditions do you get stable atherosclerotic plaques?

A

Stable angina

Intermittent claudication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is an unstable atherosclerotic plaque?

What symptoms will be seen?

A

The plaque ruptures. Platelets are then recruited and cause acute thrombosis.
The symptoms will be sudden onset. They will depend on the area.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Give examples of conditions with unstable atherosclerotic plaques?

A

Unstable angine, MI’s, stroke.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does unstable atherosclerotic plaques eventually lead too?

A

Organ ischaemia and infarction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the relationship between platelets and arterial thrombus?

A

The plaque ruptures in the high pressure environment of the arteries. The endothelium is exposed and VWF is exposed, meaning platelets adhere to it. Platelets become activated releasing granules that activate coagulation and recruit other platelets to the developing plug.
Platelet aggregation occurs via membrane glycoproteins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are some risk factors for arterial thrombosis?

A
Any factors causing damage to the endothelium, increase in foamy macrophages and platelet activation. 
Hypertension (damage to endothelium, platelets)
Smoking (endothelium, platelets)
High cholesterol (accumulates in the plaque)
Diabetes mellitus (endothelium, platelets, cholesterol)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How can you prevent arterial thrombosis?

A
Stop smoking
Treat hypertension
Treat diabetes
Anti-platelet drugs
Lower cholesterol
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How do platelets bind to collagen when they are forming the platelet plug? What is the term for this?

A

Via VWF and glycoprotein 1b.

Called adhesion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What occurs during aggregation of the platelet plug?

A

Platelets attach to each other via GPIIbIIIa and fibrinogen. At the same time as this activation is occurring.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is activation of platelets?

A

Platlets alter their shape to expose more phospholipid on the surface- providing a greater surface area for coagulation activation and fibrin clot formation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What augments the activation of platelets?

A

Augmented by release of granules that further stimulate platelet activation e.g. thrombin, thromboxane A2 and ADP In order to recruit more platelets into the process. This occurs via receptors to ADP on the platelet surface.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does aspirin work?

A

It inhibits cyclo-oxygenase (COX) which is necessary to produce thromboxane A2 (a platelet agonist released from granules)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Side effects of aspirin?

A

Bleeding
Blocks production of prostaglandins
Gi ulcers
Bronchospasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What other anti platelet drugs exist?

A

Clopidogrel and prasugrel- they work by being ADP receptor antagonists.
Dypiridamole- phosphodiesterase inhibitor- reduces production of cAMP which is the ‘second messenger’ in platelet activation

17
Q

How do GPIIb/IIIa inhibitors work?

A

They inhibit aggregation of the platelet plug. e.g. abciximab.

18
Q

When should you stop anti platelet drugs before operations?

A

7-10 days before as the anti platelet drugs affect platelets for their lifespan (which is 7-10 days).

19
Q

How can you reverse the effects of anti platelet drugs in serious bleeds?

A

Platelet transfusion.