Acute Myocardial Infarction

Question 1

What is Acute Coronary Syndrome? (ACS)

Answer 1

acute presentation of coronary artery disease – covers a spectrum of conditions, it is a provisional diagnosis
- dynamic stenosis

Question 2

What is Chronic Stable Angina?

Answer 2

leads to fixed stenosis

demand led ischaemia

Question 3

What is stenosis?

Answer 3

Narrowing of the heart valves

Question 4

What are ACS?

Answer 4

Myocardial Infarction
Unstable Angina
Cardiac Death

Question 5

What is the difference between ACS and Chronic Angina?

Answer 5

ACS = dynamic stenosis

Chronic Angina = fixed stenosis

Question 6

What factors affect plaque rupture?

Answer 6

lipid content of plaque
thickness of fibrous plaque
sudden changes in intraluminal pressure or tone
bending and twisting of an artery during each heart contraction
plaque shape
mechanical injury

Question 7

What are the assoicated symptoms of MIs?

Answer 7

nausea
vomiting
sweating

Question 8

What ECG changes would you see in a STEMI?

Answer 8

ST elevation would be flat
T wave inversion
Always a Q wave

Question 9

What does Left Bundle Branch block usually signify?

Answer 9

STEMI

Question 10

What protein and enzyme tests can you do to diagnose a STEMI from a NSTEMI?

Answer 10

Enzyme CK – creatinine kinase (not used anymore)

Protein Marker – Tn Troponin: highly specific for cardiac muscle damage can detect tiny amounts of myocardial damage

Question 11

What Antiplatelet drugs may be used in an MI?

Answer 11

Aspirin (300mg)

Clopidogrel (300mg)

Question 12

Give examples of reperfusion surgery?

Answer 12

PCI and thrombolysis

Question 13

What are the indications that a patient should undergo reperfusion surgery?

Answer 13

Chest pain suggestive of acute MI
ECH changes – ST elevation and Left Bundle Branch Block
No contraindications

Question 14

What are the risks of thrombolysis?

Answer 14

Failure to re-perfuse
Haemorrhage – minor, major, intracranial haemorrhage
Hypersensitivity

Question 15

If you cannot access PCI in 20 minutes what should you do?

Answer 15

Community thrombolysis

Question 16

Outline the early STEMI treatment?

Answer 16

• analgesia – diamorphine IV
• anti–emetic – iv
• Aspirin and Clopididogrel – 300mg
• GTN if BP > 90mmHg
• Oxygen – if hypoxic
• Primary Angioplasty
• Thrombolysis – if angioplasty is not available

Question 17

What are the complications of an acute MI?

Answer 17

• Death
• Arrhythmic complications
• Structural complications
• Functional complications

Question 18

Give detail on the structural complications of an acute MI?

Answer 18

left ventricular aneurysm formation
inflammation
acute pericarditis
dresslers syndrome
mural thrombus

Question 19

Give detail on the functional complications of an acute MI?

Answer 19

Acute ventricular failure (left, right and both)
chronic cardiac failure
cardiogenic shock

Question 20

What is the KILLIP Classifications of in hospital heart failure mortality?

Answer 20

1. No signs of heart failure
2. Crepitations <50% lung fields
3. Crepitations >50% lung fields
4. Cardiogenic shock

Question 21

Describe the 3 types of troponin? Which two show he microscopic zone of myocyte necrosis?

Answer 21

I – cardiac specific isoforms – in absence of Ca binds to actin, inhibits actin-myosin ATPase induced contraction
C – identical heart and skeletal muscle - binds to calcium
T – cardiac specific isoform – links troponin complex to tropomyosin, facilitates contraction

TnI and TnT

Question 22

When is TnT also elevated?

Answer 22

CCF
Hypertensive crisis
renal failure
pulmonary embolism
sepsis
stroke/TIA
pericarditis
myocarditis
post arrhythmia