ACS Flashcards
What comes under ACS?
Unstable angina, NSTEMI, STEMI or sudden cardiac death
What are the features of a vulnerable plaque?
- Thin fibrous cap
- Inflam. cell infiltrates > proteolytic activity
- Lipid-rich plaque
What are the features of a stable plaque?
- Thick fibrous cap
- SMC’s + more ECM
- Lipid poor plaque
What happens when a plaque ruptures?
Platelet aggregation + activation > Thrombus
What causes platelet adhesion to endothelium?
BV exposed collagen > contact with platelet > release of TAXA2, ADP, Serotonin > chemokines cause platelets to change shape + express GBIIb.IIa receptor > once receptors activation of coag cascade = thrombin
Thrombin converts fibrinogen > fibrin = laid over platelets
Ruptured plaque > super adherent thrombus > can occlude BV > ACS
What is a STEMI and how is it treated?
- Coronary artery blocked
- Need to open BV
- Mechanical (stent) + pharmacological
- Aspirin + prasugrel/tricagrelor > cath lab > heparin
What is an NSTEMI and how is it treated?
- Coronary artery not blocked
- Pt acutely ischaemic
- Treated with anti-platelet therapy then angiogram to find where to stent later
- Aspirin + Clopidogrel
- High risk = more potent antiplatelet - prasugrel/tricagrelor > cath lab > heparin
What is the purpose of anti-platelet therapy?
Reduce ability of blood to clot
What is the MOA of Aspirin?
Blocks COX in PGHS so no TXA2
What is the MOA of Clopidogrel?
ADP receptor blocker (ADP binding to platelets stimulates platelet aggregation)
What is the MOA of of Prasugrel?
ADP receptor blocker
Quicker + more potent
Metabolised by CYP450
What is the MOA of Tricagrelor?
Reversible ADP blocker
What are GBIIb.IIa inhibitors used for?
Most potent, only IV
Only used for STEMI in cath lab
What is the purpose of anti-coagulant therapy?
Prevents blood clots
What is the MOA of Heparin?
Complexes with antithrombin 3 (breaks down thrombin), making it more potent
Narrow therapeutic index