Acute coronary syndromes Flashcards
Cardiac chest pain generally presents due to 1 of 4 causes
What are these?
New exertional angina - most common
Unstable angina
Acute MI
Sudden cardiac death
What is the difference between stable and unstable angina?
Stable angina only occurs on exertion - when myocardial demand for oxygen increases past supply
What are the key symptoms/signs of stable angina?
Central chest tightness - often with radiation to neck and/or arms
Aggravated by exertion or stress
Relief by stopping activity & rapid improvement with sublingual nitrate (GTN spray)
What aspect of WIrchow’s triad causes angina?
Changes of vessel wall
Angina causes by atherosclerotic plaque in coronary arteries
How big does a plaque need to be to cause stable angina?
Obstructive plaque
Occludes >70% of the lumen
How big does a plaque need to be to risk acute coronary syndromes?
It is not the plaques size that really matters (although it has to be»_space;70% occlusion)
ACS’s caused by spontaneous plaque rupture & local thrombosis with occlusion
Plaque rupture causes the formation of ___________
Atherothrombosis
What is included in ‘Acute coronary syndromes’?
Unstable angina
NSTEMI - Non ST segment elevation MI
STEMI - ST segment elevation MI
Sudden cardiac death
What is the basic difference between symptoms of stable angina and of ACS?
ACS will give symptoms at rest whereas stable angina is only on exertion
What are the risk factors for coronary artery disease?
Age, gender, family/genetics, creed (the usual)
Previous angina, other cardiac events & interventions
Smoking Diabetes Hyperlipidaemia Hypertension Lifestyle
Describe the typical presentation of Unstable angina pectoris (UAP)
UAP, angina on effort, but of progressive, increasing frequency & severity
Often provoked by less exertion and/or then at rest
“It started when I was walking up the stairs so I sat down but the pain just kept on getting worse”
Describe the typical presentation for NSTEMI
Myocardial ischaemic symptoms occurring at rest
“I was sitting watching eastenders and all of a sudden i had a really tight pain on my chest”
How would you examine someone with suspected UAP or NSTEMI?
Might look like shite but also might look fine
Not really any specific signs/features to find
Check:
- HR & BP
- Auscultate for murmurs & crackles in chest
What piece of kit is needed to diagnose NSTEMI (or STEMI)?
ECG
What features on an ECG would you look for, for UAP and NSTEMI, on an ECG?
You would look at:
ST segment:
- ST depression?
- Transient ST elevation?
- T wave inversion?
If the patient’s pain has gone:
- Is the ECG normal? = UAP (generally)
- Is the ECG abnormal? = NSTEMI (generally)
Why must you take ‘serial ECGs’?
To detect late changes
This is essential in differentiation UAP & NSTEMI (and in general diagnosis)
How often are ACS symptoms ‘Atypical’?
Atypical symptoms are relatively common
Atypical symptoms more common in:
- Women
- Elderly
- Diabetics
What are the typical atypical symptoms for UAP & NSTEMI?
Breathlessness alone +/- signs of heart failure
Nausea & vomiting +/- other autonomic symptoms
Epigastric pain +/- indigestion
Why would you take bloods of someone presenting with cardiac pain?
What biomarkers would be looked for?
Cardiac biomarkers are useful in diagnosing UAP & NSTEMI
Cardiac troponin (cTn) I & T
Useful for:
- Diagnosis
- Risk stratification
- High cTn indicates risk of adverse events
If someone presents with cardiac chest pain and all the symptoms of ACS
Why can you not make a diagnosis entirely from their bloods?
Elevated troponin (cTn) can be caused by may different things, not just ACS & atherothrombosis
What is cardiac troponin?
cTn - the contractile apparatus of myocytes thin (actin) filaments
Cardiac troponin is unique and is only detectable in the blood if myocyte intergrity is compromised (this makes their levels elevate)
Why can’t you measure the cTn levels in someones blood immediately after they present with ACS?
cTn blood levels take a while to rise after acute ischaemia
They have a characteristic rise & fall of blood levels
Contrast the levels of elevation of cTn in the blood after different ACSs
Acute MI - massive (largest) increase in cTn levels
UAP - smaller increase in cTn levels
As UAP causes a smaller elevation, there is a AMI reference limit, so if cTn levels rise above it, they know it is AMI
Aside from cTn, what other molecules’ levels in the blood can be measured to help identify & diagnose acute MI?
Myoglobin
CK-MB