Week 3- arterial thrombosis and anti-platelet drugs Flashcards
Is atherosclerosis the same as arterial thrombosis?
What is atherosclerosis?
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.
when is an atherosclerotic plaque stable?
When it is hylanised and calcified.
In what conditions do you get stable atherosclerotic plaques?
Stable angina
Intermittent claudication
What is an unstable atherosclerotic plaque?
What symptoms will be seen?
The plaque ruptures. Platelets are then recruited and cause acute thrombosis.
The symptoms will be sudden onset. They will depend on the area.
Give examples of conditions with unstable atherosclerotic plaques?
Unstable angine, MI’s, stroke.
What does unstable atherosclerotic plaques eventually lead too?
Organ ischaemia and infarction.
Describe the relationship between platelets and arterial thrombus?
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.
What are some risk factors for arterial thrombosis?
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 can you prevent arterial thrombosis?
Stop smoking Treat hypertension Treat diabetes Anti-platelet drugs Lower cholesterol
How do platelets bind to collagen when they are forming the platelet plug? What is the term for this?
Via VWF and glycoprotein 1b.
Called adhesion
What occurs during aggregation of the platelet plug?
Platelets attach to each other via GPIIbIIIa and fibrinogen. At the same time as this activation is occurring.
What is activation of platelets?
Platlets alter their shape to expose more phospholipid on the surface- providing a greater surface area for coagulation activation and fibrin clot formation.
What augments the activation of platelets?
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 does aspirin work?
It inhibits cyclo-oxygenase (COX) which is necessary to produce thromboxane A2 (a platelet agonist released from granules)
Side effects of aspirin?
Bleeding
Blocks production of prostaglandins
Gi ulcers
Bronchospasm