Acute Coronary Syndromes

Question 1

Define ACS

Answer 1

Umbrella term for syndromes where blood supply to the heart is impaired, leading to myocardium damage

Question 2

Common SYMPTOMS of cardiac ischaemia?

Answer 2

Central crushing chest pain that may remit within minutes following exacerbation
May radiate to neck, abdomen or inner left arm (T1)
Relived by rest of sublingual nitrate (GTN)

Question 3

Differential diagnoses for ACS?

Answer 3

Reflux oesophagitis (not effort related)
Costochondritis (reproducible on palpation)
Musculoskeletal pain (reproducible on movement)
Pericarditis (sharp, better on rest, ECG shows universal ST elevation)
Mediastinitis (inflammatory markers raised, really ill)
Gastritis (modified by eating, epigastric pain)

Question 4

Common SIGNS of cardiac ischaemia?

Answer 4

Bibasal crackles, weakness, dizziness, low SpO2, central/peripheral cyanosis, raised JVP, pallor, hypotension, diaphoresis

Question 5

Differences between unstable angina, STEMI, NSTEMI?

Answer 5

Unstable angina - Myocardial ischaemia without detectable Myocardial necrosis

NSTEMI - shows evidence of necrosis by raised troponin but no ECG characteristics

STEMI - ST elevation on ECG

Question 6

What does ischaemia show on ECG? Infarction?

Answer 6

ST depression/T wave invertion

ST elevation in infarction

Question 7

Pathophysiology of NSTEMI/UA?

Answer 7

Transmural thrombus with variable occlusion - may embolise downstream to occlude vessel

Question 8

Pathophysiology of STEMI?

Answer 8

Occlusive thrombus leading to acute transmural myocardial infarction

Question 9

Phases of MI?

Answer 9

Ischaemic phase several minutes - survives on anaerobic metabolism

Infarction phase - anaerobic metabolism cannot keep up with demands, irreversible damage and cell death
= affected area contributes less to depolarisation

Question 10

MI treatment?

Answer 10

Anticoagulants (Heparins, Dabigatran, Warfarin)
Antiplatelets (Aspirin, Clopidogrel)
Thrombolytics (alteplase, urokinase, streptokinase)
Invasive strategies

Question 11

Diagnostically, how can you differentiate between NSTEMI, STEMI and Unstable Angina?

Answer 11

Chest pain -> ACS
ECG: ST elevation = STEMI
No ST elevation then check Troponin levels (indicative of myocardial cell death)
Raised troponin = NSTEMI
Normal troponin = unstable angina (as just ischaemia no infarction)

Question 12

Where will you get oedema with R and L sided heart failure?

Answer 12

R side - fluid backs up in systemic circulation so raised JVP, lower leg, sacral

L side - pulmonary oedema as fluid backs up into the lungs

Question 13

What are some complications of ACS?

Answer 13

Hypotension 
Cardiogenic shock (hypovolaemia)
AKI
Tachy/brady-arrhythmias
Pericarditis
Recurrent ischaemia

Question 14

What actually is stable angina?

Answer 14

Narrowing of cardiac arteries = when exercising so increased O2 demands and blood flow, ischaemia arises

Relief with GTN spray confirms artery vasoconstriction

Question 15

What else can cause raised Troponin levels?

Answer 15

Renal failure

Question 16

How does a platelet-fibrin thrombus form from vascular injury?

Answer 16

Two pathways:
Platelet aggregation pathway: exposure of collagen + vWF, platelet adhesion, platelet recruitment

Fibrin formation: tissue factor exposure, coagulation, thrombin generation -> fibrin

Question 17

What’s the difference between ST elevation and ST depression?

Answer 17

ST elevation caused by infarction (and pathological Q wave formation)

ST depression (and T wave inversion) caused by ischaemia