Arterial Thrombosis and Antiplatelets

Question 1

What is atherosclerosis?

Answer 1

not the same as arterial thrombosis

Damage to endothelium leads to recruitment of ‘foamy’ macrophages rich in cholesterol, forming plaques

Question 2

Name 2 conditions where there are stable plaques.

Answer 2

stable angina (coronary artery), intermittent claudication (leg artery)

Question 3

Name some conditions where there are unstable/ruptured plaques.

Answer 3

Unstable angina or myocardial infarction (coronary arteries)

Stroke (cerebral arteries)

Question 4

What do ruptured plaques lead to?

Answer 4

Leads to acute organ ischaemia and infarction

Question 5

How are platelets involved in arterial thrombosis?

Answer 5

platelet plug formation occurs at ruptured plaque

Question 6

The process of platelet plug formation around a ruptured plaque is augmented by release of granules that further stimulate platelet activation - what are these? What do they do?

Answer 6

Thrombin,Thromboxane A2 and ADP

recruit more platelets to the process.

Question 7

How does aspirin work?

Answer 7

Inhibits cyclo-oxygenase which is necessary to produce Thromboxane A2 (a platelet agonist released from granules on activation)

Question 8

Side effects of aspirin?

Answer 8

1. Bleeding
2. Blocks production of prostaglandins:
   - GI ulceration
   - Bronchospasm

Question 9

What type of drugs are Clopidogrel, prasugrel ?

Answer 9

ADP receptor antagonists

Question 10

What is Dipyridamole?

Answer 10

Phosphodiesterase inhibitor -reduces production of cAMP which is a ‘second messenger’ in platelet activation

Question 11

Give an example of a GP IIb/IIIa inhibitor, and what does this inhibit?

Answer 11

abciximab - inhibits aggregation

Question 12

When should anti-platelet agents be stopped prior to operation?

Answer 12

7 days before

Question 13

Are platelets involved in venous thrombosis?

Answer 13

not really no