Arterial Thrombosis and Anti-Platelet Drugs Flashcards
(27 cards)
What cells are key to arterial thrombosis?
Platelets
What causes atherosclerosis?
Macrophages and cholesterol are pushed into vessel wall = may rupture and attract platelets
What is the first step in atherosclerosis?
Damage to endothelium
Why are atherosclerotic plaques rich in cholesterol?
Foamy macrophages rich in cholesterol are recruited when there is endothelial damage
What are the features of stable plaques?
Hyalinised and calcified
Can cause stable angina and intermittent claudication
What are the features of unstable plaque?
May rupture and recruit platelets to cause an acute thrombosis = cause acute organ ischaemia/infarction
Sudden onset of symptoms
Cause unstable angina, MI or stroke
Why are plaque ruptures more likely in arteries?
Due to the high pressure environment
What are the steps of arterial thrombosis formation?
Platelet adherence, activation and aggregation
What causes platelets to adhere to plaque ruptures?
Exposed collagen and vWF
What occurs when platelets are activated?
Release granules that activate coagulation and recruit other platelets to the developing plug
What causes platelet aggregation?
Occurs via membrane glycoproteins
What are the risk factors for arterial thrombosis?
Endothelial damage, increase in foamy macrophages and platelet activation
What are some conditions that increase the risk of arterial thrombosis?
Hypertension, smoking, high cholesterol, diabetes
What are some preventions against arterial thrombosis?
Stop smoking, treat hypertension and diabetes, lower cholesterol, anti-platelets
What do platelets bind to in order to stick to exposed subendothelial collagen?
Glycoproteins Ib and vWF
What receptors allow platelets to bind to each other?
GP IIb/IIIa and fibrinogen
What is the first step in platelet activation?
Platelets alter their shape to expose more phospholipid on their surface
What effect do platelets changing their shape have?
Provides greater surface area for coagulation and fibrin production to stabilise the clot
What augments the process of platelet activation?
Release of granules which further stimulates activation = thrombin, thromboxane A2, ADP
What is the action of aspirin?
Inhibits COX which is necessary to produce thromboxane A2
What is the action of thromboxane A2?
Acts as platelet agonist = released from granules on activation
What are the side effects of aspirin?
Bleeding, blocks prostaglandin production, GI ulceration, bronchospasm
What is the action of clopidogrel?
ADP receptor antagonist
What is the action of dipyridamole?
Phosphodiesterase inhibitor which reduces cAMP production = less commonly used
