Acute Coronary Syndromes Flashcards
What is chronic stable angina? (Not an acute coronary syndrome)
Fixed stenosis within the coronary artery
Demand lead ischaemia - ischaemia only comes on when demand is on the heart
This makes it predictable
Safe symptoms
How to relieve symptoms of chronic stable angina? (Not an acute coronary syndrome)
Ask patients to stop and sit down = reduce work rate of heart
Take GTN spray - decreases blood pressure, reduces afterload on the heart, may cause coronary vasodilation to bring about sensation to chest pain
How can cardiac chest pain be described?
Heavy feeling
Weight on chest
Pressure, tightness
Usually in centre of chest and radiating to jaw and arms
What is an acute coronary syndrome?
Any acute presentation of coronary artery disease
Only a provision of diagnosis that covers a spectrum of conditions
Why are the Acute coronary syndromes?
Unstable angina > acute non-STEMI (ST elevation MI), non-Q wave, sub-endocardial MI > STEMI, AMI, Q wave MI
What is the pathogenic trigger for coronary syndromes
Atherosclerotic plaque develops until spontaneous plaque rupture/fissure and thrombosis and acute occlusion of a vessel
What is unstable angina/MI?
Dynamic stenosis (subtotal or complete occlusion)
It is supply led ischaemia
It is very unpredictable (can happen at rest)
Dangerous
What causes plaque rupture?
Cause still debatable but:
Lipid content and thickness - Young fatty plaques more at risk of rupturing
Sudden changes in pressure/tone or bending in vessel
Plaque shape
Mechanical injury
How is a blood clot formed?
Damage to vessel wall or spontaneous plaque rupture - sub-endothelial tissue to blood
Platelet = initiator
Platelet forms a monolayer over the site of vascular injury (recruitment and adhesion of platelets at injury)
Monolayer develops and leads to adhesion of circulating platelets
How is left sided heart failure caused? (This is associated with mortality)
Patents that survive MI of left coronary artery-
Muscle in left ventricle damaged and is replaced with scar tissue
Volume in left ventricular cavity increases and heart function decreases as volume decreases
Loss of muscle function
What is the first step in diagnosing an ST elevation MI (highest risk ACS)?
History:
Severe crushing central chest pain (similar to angina if they previously had it but is more severe and prolonged)
Radiating to jaw and arms (especially left)
Not relieved by GTN
Sweating nausea and sometimes vomiting
Differentiation of angina vs acute MI
Angina:
Lasts 10 mins
Occurs on exertion
Severity: usual pain
GTN:relief
Usually no associated symptoms
MI:
Lasts 30+mins
Occurs at rest
Severe pain
GTN: no effect
Sweating, nausea, vomiting associated symptoms
What is the next step in diagnosing an ST elevation MI?
An ECG
Looking for:
ST elevation
- >1mm ST elevation in 2 adjacent limb leads
-> 2mm ST elevation in at least 2 contiguous pericardial leads
- new onset bundle branch block
T wave inversion
Q waves
How to tel the difference from an acute MI (happening now) to an “old MI”
Acute - ST elevation = first few hours
Old MI - Q waves +/- nerve that T waves
Diagnosis using cardiac enzymes and protein markers
Markers may be normal at presentation and we dont have time to wait for results in STEMI
We use protein marker - Tn - troponin
> highly specific for cardiac muscle damage
> can detect tiny amounts of myocardial necrosis
What is the criteria to determine MI
A rise and/or fall of a cardiac biomarker values (preferably cardiac troponin) with at least on value above the 99* percentile upper reference limit, and at least ONE of the following:
- Symptoms of ischaemia
- New significant ST-segment T-wave (ST-T) changes or new left bundle branch block
- Development of pathological Q waves in the ECG
- Imaging evidence of new loss of viable myocardium or new regional wall motion abnormality
- Identification of an interacoronary thrombus by angiography or autopsy
What is early treatment of ST elevation MI?
1st line aspirin and clopidogrel (antiplatelet)
In the presence of ischaemic electrocardiograph if changes or elevation of cardiac troponin, patients with acute coronary syndrome should be treated immediately with what?
Aspirin (300mg loading dose) AND ticagrelor (180mg loading dose)
For patients with acute coronary syndrome undergoing percutaneous coronary innervation, what drugs/treatment should be considered?
Aspirin and Prasugrel (60 mg loading dose)
For patients with acute coronary syndrome that have greater risks (bleeding) than the benefits (reduction in recurrent atherothrombotic events) when on ticagrelor or prasugrel should be considered for what drugs instead?
Aspirin (300mg loading dose) and clopidogrel (300mg loading dose)
What is the central pathway to platelet aggregation and therefore Acute MI, stroke or death?
Activation of platelet
Activator released, aggregation, inflammation
Vascular blockage
Acute MI, stroke or death
How should aspirin be taken and why?
In tablet form
Starts at a loading dose of 300mg
Patients asked to chew tablet to increase surface area to start immediate absorption