Flashcards in Arterial Thrombus and Antiplatelet Drugs Deck (45)
What are the 2 main types of thrombotic event?
1. Arterial: conorary, cerebral, peripheral
2. Venous: DVT, PE
What type of drug is used to treat an arterial thrombus?
What type of drug is used to treat a venous thrombus?
Arterial thrombus are found in a ____ pressure system
How do arterial thrombus form?
* Atherosclerosis narrows the blood vessel
* This damages the vessel wall
* vWF recruits platelets
* Platelets come and aggregate
* PLATELET RICH THROMBUS is formed
How is an arterial thrombus treated?
* Aspirin and other anti-platelet drugs (e.g. clopidogrel).
* Modify risk factors for atherosclerosis.
What is atherosclerosis not the same as?
Describe how atherosclerosis forms.
* Damage to endothelium.
* Recruitment of ‘foamy’ macrophages rich in cholesterol.
* Forms plaques rich in cholesterol.
Describe stable atherosclerotic plaques.
Hyalinised and calcified
What are the 2 clinical conditions that people get from having a stable atherosclerotic plaque?
* Stable angina (coronary artery).
* Intermittent claudication (leg artery).
How does an unstable atherosclerotic plaque cause an acute thrombus?
Plaques rupture, damage to endothelium, platelets are recruited and cause acute thrombosis
What symptoms arise from an acute thrombus?
Sudden onset sx:
* Unstable angina or myocardial infarction (coronary arteries).
* Stroke (cerebral arteries).
What can an acute thrombus ultimately lead to?
**** LEADS TO ACUTE ORGAN ISCHAEMIA AND INFARCTION ****
In what type of environment is the rupture of a plaque more likely to happen?
In the high pressure environment of arteries.
Outline how an arterial thrombus develops after the rupture of a plaque?
* Platelets adhere to the ruptured plaque – exposed endothelium and release of Von Willebrand factor.
* Platelets become activated – release granules that activate coagulation and recruit other platelets to developing platelet plug.
* Platelet aggregation via membrane glycoproteins.
What do all the risk factors for an arterial thrombus ultimately do?
Cause damage to the endothelium, increase in foamy macrophages and platelet activation.
List risk factors for arterial thrombus (and state what they effect).
* Hypertension – damage to endothelium, platelet activation.
* Smoking – endothelium, platelets.
* High cholesterol (accumulated in plaque).
* Diabetes mellitus (endothelium, platelets, cholesterol).
How can an arterial thrombus be prevented?
* Stop smoking.
* Treat hypertension.
* Treat diabetes.
* Lower cholesterol.
* Anti-platelet drugs.
The venous system is a ____ pressure system
What triad is important in understanding the aetiology of a venous thrombus?
* Vessel wall (valves not atheroma).
* Hypercoagulability (high clotting factors).
The clot in a venous thrombus is ______ rich
How is a venous thrombus treated?
Where are platelets formed? How?
In the bone marrow, by ‘budding’ from megakaryocytes.
Describe the appearance of platelets.
Small anucleate discs
What is the lifespan of a platelet?
Explain the steps which lead to PLATELET ADHESION at the site of injury.
Endothelial (vessel wall) damage exposes collagen, Von Willebrand Factor, and other proteins to which platelets have receptors.
After platelet aggregation has occurred at a site of injury what happens?
There is then secretion of various chemicals from the platelets (eg ADP, thromboxane A2), which leads to aggregation of platelets at the site of injury.
What are the 3 main stages (3 A's) in the formation of a platelet plug?
Describe what happens in adhesion.
Platelets bind to subendothelial collagen via glycoprotein 1b and vWF.