Acute coronary syndrome

Question 1

Unstable angina

Answer 1

1. Atherosclerotic plaque within the coronary artery ruptures forming a thrombus
   • 70% stenosis
   • Ischaemia at rest - pain without exertion

Question 2

Consequences of unstable angina

Answer 2

• Subendocardial ischaemia - inner most of the heart muscle is deprived most of oxygen as coronary arteries begin at the epicardium
• Progress to NSTEMI/STEMI

Question 3

Non ST elevation MI

Answer 3

• thrombus with higher degree of stenosis
• Infarction of inner most cardiac tissue
• Ischaemia of outer epicardium closest to blood supply

Question 4

ST elevation MI

Answer 4

• thrombus completely obstructs coronary artery
• blood supply to heart muscle is cut off completely
• Severe ischaemia and necrosis

Question 5

Consequence of STEMI

Answer 5

• Transmural infarction - necrosis of all layer sof heart muscle
• Damage to papillary muscles cayses regurgitation and prolapse of valves

Question 6

consequences of acute coronary syndrome ( 4)

Answer 6

1. Cardiogenic shock
   - more than 40% of LV has been infarcted
   - hypotension and decreased CO
   - hypotension leads to decreased coronary perfusion , exacerbates ischaemic damage
2. Arrythmia
   - Ventricular fibrillation and conduction block
3. Congestive heart failure
   - ischaemia results in impaired ventricular contraction and increased myocardial stiffness
4. Angina
   - ischaemia of myocytes causes lactic acid to build up and adenosine to be released which activates pain fibres

Question 7

Serum markers of infarction

Answer 7

heart cells become damaged and proteins within the myocytes become released
1. Troponin T and I levels are elevated
• Stay elevated for 7-10 days after
2. Creatine Kinase M + B
•Elevated in 2-4 hours
• Return to normal within 24 hours - helpful in identifying reinfarction