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Medicine - Cardiology > Emergency - Acute coronary syndromes > Flashcards

Emergency - Acute coronary syndromes Flashcards

1
Q

Describe the pathophysiology of coronary artery disease.

A
  • Atherosclerotic plaque formation narrows the coronary artery. The atherosclerotic plaque may rupture and lead to thrombus formation, further narrowing the coronary artery.
  • This reduces blood flow and hence the delivery of oxygen and glucose to the myocardium, resulting in ischaemia.
  • Depending on the extent of narrowing, the ischaemia may:
    • only be present when there is an increased demand for oxygen and glucose during exertion (stable angina)
    • or may be present at rest (acute coronary syndrome)
  • If the narrowing is severe enough, ischaemia can result in necrosis and the myocardium undergoes infarction.
    • Partial occlusion of the artery (NSTEMI)
    • Complete occlusion of the artery (STEMI)
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2
Q

Describe the formation of an atherosclerotic plaque.

A
  1. Chronic endothelial injury - raised LDL, toxins, hypertension
  2. Endothelial dysfunction with platelet adhesion and monocyte acccummulation, causing release of growth factors and cytokines
  3. Smooth muscle emigration from tunica media to tunica intima
  4. Macrophages and smooth muscle cells engulf lipid to form foam cells
  5. Smooth muscle proliferation, collagen and matrix deposition, extracellular lipid deposition and neovascularisation
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3
Q

What is meant by the stability of an atherosclerotic plaque?

A

An unstable atherosclerotic plaque is more likely to rupture and lead to thrombus formation.

  • Rupture of the plaque allows blood to enter the plaque
  • This causes smooth muscle constriction which narrows the artery
  • Thrombus formation can occlude the artery completely
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4
Q

Which clinical syndromes are classed as acute coronary syndromes?

A

Unstable angina

Non-ST-elevation myocardial infarction

ST-elevation myocardial infarction

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5
Q

How can unstable angina present?

A
  1. Angina on exertion with increasing frequency over a few days, provoked by less exertion (crescendo angina)
    or
  2. Angina occurring recurrently and unpredictably - not specific to exercise
    or
  3. Unprovoked and prolonged episode of chest pain
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6
Q

ECG and Troponin in unstable angina?

A
  • Non-specific ECG change OR commonly, a normal ECG
    • T wave inversion
    • ST segment depression suggests high risk of progressing to MI
  • No troponin release
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7
Q

ECG and Troponin in NSTEMI?

A
  • Non-specific ECG abnormalities (usually these are present, though ECG can be normal)
    • ST segment depression
    • T wave inversion
  • Troponin release
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8
Q

What differentiates unstable angina and NSTEMI?

A

Unstable angina - no troponin release (no myocardial cell death)

NSTEMI - TROPONIN RELEASE (MYOCARDIAL CELL DEATH)

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9
Q

Does a STEMI require troponin to confirm diagnosis?

A

NO

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10
Q

Does an NSTEMI require troponin to confirm diagnosis?

A

YES

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11
Q

What are the typical features of an acute MI?

A
  • prolonged chest, throat or arm pain
    • usually lasts for 20 mins or longer
  • SOB
  • clammy
  • nauseous
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12
Q

Is the immediate management of an NSTEMI and STEMI the same?

A

NO

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13
Q

ECG and Troponin in STEMI?

A
  • ECG - Acute ST-segment elevation / new LBBB
    • Q waves likely to develop
  • Troponin release

(ECG shows STEMI in lateral limb leads and anterior chest leads, the anterior chest leads show pathological q waves)

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14
Q

What do pathological q waves represent?

A

myocardial necrosis

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15
Q

What is the difference between the immediate management of an NSTEMI and STEMI?

A

STEMI - immediate reperfusion therapy

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16
Q

Early effective treatment (including reperfusion therapy) may limit myocardial damage and prevent Q wave development in STEMI.

True or False?

A

TRUE

17
Q

What is common to the immediate management of ALL acute coronary syndromes?

A

ABCDE approach + MONA

M – morphine 2-5mg IV PRN

O – oxygen if indicated (sats<94%) 2-4L via nasal cannula

N – nitrate 0.4mg sublingual (GTN spray) / IV

A – aspirin 300mg chewable/crushed

18
Q

A patient presents with suspected ACS. ABCDE + MONA immediate management is initiated. Once diagnosis of NSTEMI or Unstable angina is confirmed, what are your next steps in management?

A

Partial occlusion so prevent the clot from getting bigger:

  • Second anti-platelet drug - clopidogrel, prasugrel or ticagrelor
  • Enoxaparin/fondapurinax for 48 hour

Urgent invasive intervention for high risk patients (recurrent chest pain, uncertain ECG features):

  • Tirofiban and urgent angiography within 96 hours with probable stent insertion

Continue with MON:

  • Nitrate - sublingually or infusion
  • Morphine - if pain does not respond to above
  • Oxygen - if hypoxic

Myocardial protection:

  • Beta-blocker - bisoprolol
  • Coronary angiography/PCI in most patients - not as an emergency but usually during same admission

Frequently reassess patient and cardiac monitoring is required

19
Q

A patient presents with suspected ACS. ABCDE + MONA immediate management is initiated. Once diagnosis of STEMI is confirmed, what are your next steps in management?

A

Call cath-lab immediately and activate PPCI pathway for emergency reperfusion therapy (PCI/thrombolysis).

  • Percutaneous coronary intervention (PCI)
  • Fibrinolytic therapy only if no access to primary PCI

Avoid delay, coronary artery is occluded and needs to be opened up - “Time is muscle”. If there is any doubt about PCI or fibrinolysis, discuss with cardiology team at nearest hospital offering PCI.

20
Q

A patient presents with chest pain and this ECG. A previous ECG from a few months ago showed sinus rhythm. Diagnosis?

A

New LBBB - treated as STEMI

Immediate primary percutaneous intervention or fibrinolysis if PCI is not available

21
Q

What are the absolute contraindications for fibrinolytic therapy?

A
  • Previous haemorrhagic stroke
  • Other stroke or CVA within six months
  • CNS damage or neoplasm
  • Active internal bleeding
  • Aortic dissection
  • Recent major surgery or trauma
  • Known bleeding disorder
22
Q

What should be done if a patient presents with a STEMI and has a known bleeding disorder?

A

Primary PCI is a priority in this patient as fibrinolysis is absolutely contraindicated.

If there is PCI providers nearby, consider other anti-thrombotic drugs with the advice of a cardiologist.

23
Q

What is the long-term management of a patient who has been treated for an acute coronary syndrome?

A
  • Lifestyle advice – cardiac rehabilitation after MI
  • Dual anti-platelet – aspirin (lifelong) + prasugrel/ticagrelor (1 year)
  • Statin – atorvastatin
  • Beta-blocker – bisoprolol. If asthma verapamil or diltiazem. If blood pressure drops too low then ivabradine
  • ACEi/ARB – ramipril
  • GTN spray PRN
  • If they have not already had angiography then this will be done on discharge
24
Q

Name 3 non-modifiable risk factors for ACS.

A

Age

Male

Family history of IHD – MI in 1st degree relative <55 years

25
Q

Name 5 modifiable risk factors of ACS.

A

Smoking

Hypertension

Hypercholesterolaemia

Diabetes

Obesity

Previous MI, CABG or stent

26
Q

Which initial investigations would you request for all suspected ACS patients?

A
  • Bloods - troponin T and I, creatine kinase, FBC, U&E’s, HbA1c, lipids
  • 12-lead ECG
27
Q

Describe the evolving ECG changes seen in a STEMI.

A

hyperacute T waves, T wave inversion, ST elevation, ST segment recovers, T wave recovers, pathological Q waves

28
Q

What are the complications of an MI?

A

ACT RAPID

Arrhythmias – Bradycardias, heart block, tachychardia

Congestive heart failure

Tamponade

Rupture of ventricle – ventricular septal defect

Angina

PE

Infection – pericarditis

Death/Dressler’s syndrome

29
Q

Which coronary artery supplies the inferior aspect of the heart?

A

RCA

30
Q

Which coronary artery supplies the lateral aspect of the heart?

A

Circumflex (Left coronary artery)

31
Q

Which coronary artery supplies the anteroseptal aspect of the heart?

A

Left anterior descending artery (Left coronary artery)

32
Q

Which coronary artery supplies the postero-inferior aspect of the heart?

A

RCA

33
Q

What is cardiac rehabilitation?

A
  • It is available to anyone that has had an MI, coronary angioplasty or heart surgery
  • Should include: Health education, Lifestyle advice, Stress management, Physical exercise
  • It is done because: Improves clinical outcomes, Cost saving through less re-admissions
34
Q

Where are patients with an acute MI usually managed?

A

Coronary care unit

Medicine - Cardiology (8 decks)

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