Acute Coronary Syndrome
What is the function of the coronary arteries?
They supply our heart muscle with oxygen rich blood
Give me an example of a plasminogen activator
Alteplase
Give an example of an antiplatelet drug
Aspirin
Give an example of a P2Y12 inhibitor
Clopidogrel
Give an example of a beta blocker
Propanolol
Define an acute coronary syndrome
When there is a significant decrease in coronary blood flow leading to acute myocardial ischaemia
How do plasminogen activators work
They convert plasminogen to plasmin. Plasmin breaks down fibrin resulting in degradation of the thrombus
How does aspirin cause vasoconstriction?
Aspirin irreversibly inhibits COX1, inhibiting the production of TXA2 (a prostaglandin).
How do P2Y12 inhibitors work?
Inhibit the binding of ADP to platelet P2Y12 receptors, inhibiting platelet aggregation
Give an example of a statin
Simvastatin
Name 3 symptoms/events that come under Acute Coronary Syndrome?
NSTEMI
STEMI
Do plasminogen activators have a thrombogenic or thrombolytic effect?
Thrombolytic
Why can't platelets regenerate COX1, and why can vascular tissue regenerate it?
Platelets do not have a nucleus
List two beneficial effects of ACE inhibitors after a myocardial infarction
Limit infarct size
Reduce ventricular remodelling
Reduce cardiovascular mortality
How do beta blockers work?
They competitively antagonise actions of adrenaline and noradrenaline at beta adrenergic receptors, reducing the impact of the SNS on the heart and exerting an antiarrythmic effect.
Describe what STEMI is
Sudden and complete block of a coronary artery causing full thickness damage of the ventricular wall
What are some side effects of plasminogen activators
Bleeding and hemorrhage which can be life threatening (e.g. intracranial and GI bleeding)
Why are patients often told not to take aspirin a couple days before surgery?
Lifetime of a platelet is about 7 days. If you don't take aspirin for a couple days it will allow your body time to make more platelets. You don't want to bleed too much during surgery.
What can be considered as an alternative for patients who are intolerant of ACE inhibitors
Angiotension II receptor antagonists (sartans)
Describe the mechanism of action of statins
Statins inhibit the enzyme HMG-CoA reductase, and therefore inhibit an early rate limiting step in cholesterol synthesis
Outline immediate treatment of all patients with a STEMI
Dual antiplatelet therapy, and emergency reperfusion either with primary percutaneous coronary intervention (PCI) or if primary PCI unavailable -> thrombolytic therapy
What are the three stages of haemostasis?
Vascular spasm/vasoconstriction
Platelet aggregation and plug formation
Coagulation (thrombus, clot)
How can atherosclerotic plaques lead to a myocardial infarction
Plaque on inside of blood vessel walls can precipitate aggregation of platelets (plug formation) and thrombus formation. If plaques are inflammed or not as smooth or jagged, platelets can recognise this as a bleed and clump together, potentially blocking the blood vessels.
What does STEMI dual antiplatelet therapy include (two drugs)
Aspirin and a P2Y12 inhibitor (clopidogrel, prasugrel, ticagrelor)
What is the effect of statins on hepatocytes, and which two cholesterol levels do statins mainly change?
They increase the number of LDL receptors on hepatocytes, leading to an increased uptake of LDL cholesterol from the blood.
Statins result in a reduction of total cholesterol and LDL cholesterol levels.