3 Flashcards
What are two acute coronary syndromes
Unstable angina
Acute myocardial infarction
What is the underlying mechanism of ACS
Obstruction of coronary artery blood flow by a thrombus
When is unstable angina not a NSTEMI (2)
When there is no elevation of troponin (sign of myocadial damage)
No ECG changes indicative of ischemia
What do patients presenting with ST segment elevation usually require
Urgent reperfusion by fibrinolytic therapy or primary angioplasty
What is the initial management of acute MI (5)
1) Reperfusion by fibrinolysis within 6 h or percutaneous transluminal coronary angioplasty
2) Analgesia
3) Oxygen
4) Sublingual nitroglycerin
Management of acute STEMI 24 h and beyond
Aspirin or clopidogrel Anticoagulents B-blockers or CCBs ACEI Statin
What is haemostasis
Adhesion, activation and aggregation of platelets
Formation of fibrin via coagulation cascade
What is thrombosis
Haemostasis in the wrong place
Virchow’s triad
What is Virchow’s triad
Injury to vessel wall (plaque rupture)
Altered blood flow (e.g. DVT)
Abnormal blood coagulability
What is an arterial thrombus vs venous thrombus
Arterial - white, mainly platelets in fibrin mesh
Venous - red, white head red tail which can break away and form an embolus
What are two types of antithrombotic therapy
Anticoagulants
Antiplatelets
What does the formation of fibrin involve
a) Protease
b) Proteolysis
What opposes the action of proteases in the cascade
Antithrombin III
How do unfractionated heparin and LMW heparins work
Potentiate the action of antithrombin III
ATIII inactivates thrombin and Xa proteases
Is careful monitoring required with LMW heparins
No, only heparins
What is dabigatran (Pradaxa)
Direct thrombin inhibitor
To inhibit thrombin what does heparin need to bind to
Both ATIII and IIa
To inhibit Xa what does heparin need to bind to
Only ATIII???
What is warfarin
Vitamin K antagonist
How does warfarin work
Interferes with synthesis of coagulation factors
Vitamin K is essential for carboxylation of glutamic acid residues in factors II, VII, IX and X
Blocks vitamin K epoxide reductase
What do P2Y12 receptors do
Increase expression of GP IIb/IIIa receptors
What do GP IIb/IIIa receptors do
Bind fibinogen, which leads to platelet aggregation
What are antiplatelet drugs
Aspirin
Epoprostenol
Clopidegrel
Tirofiban
What is clopidegrel
P2y12 receptor antagonist
