CV 18 - Acute Coronary Syndrome

Question 1

Describe the anatomy of the coronary arteries

Answer 1

Two main coronary arteries which branch off …

1) Left Main - splits into the circumflex and left anterior descending (LAD).
2) Right - branches into the right marginal artery

• LCA feeds blood into left hand side of heart, circumflex perfuses the left ventricular wall, LAD perfuses the interventricular septum + anterior wall of LV
• Right marginal perfuses the RV.

Question 2

Which ECG leads look at the following regions of the heart:

• Antero-septal
• Inferior aspect
• Lateral aspect

Answer 2

• Antero-septal = V1-V4
• Inferior = 2,3 + aVF
• Lateral = 1, aVL, V5 + V6

Question 3

What do ST elevation, ST depression + T-wave inversion suggest on an ECG?

Answer 3

ST elevation = Sudden occlusion of a coronary artery

ST depression = Under-supply of blood to myocardium (ischaemia) but no sudden coronary artery occlusion (e.g.: unstable angina)

T-wave inversion = Under-supply of blood to myocardium but not sudden coronary occlusion. Non-ischaemic related causes.

Question 4

How are troponins used as a critical marker of MI?

Answer 4

• Typically raised within 3 hours of cardiac damage, peaking at 24-48h. Remained elevated for 2+ weeks
• Raised in many conditions, not exclusive to MI - need to diagnose alongside history, examination + ECG.

Question 5

What is the management routine of STEMI?

Answer 5

• 300mg of aspirin + 2nd anti-platelet
• Morphine for pain
• Supplemental oxygen is saturation <92%
• Direct transfer to cardiac cath lab for percutaneous coronary intervention (PCI).

Question 6

What is the management routine of NSTEMI?

Answer 6

• Have a bit more time in this case as occlusion is not complete
• Aspirin + 2nd anti-platelet
• Anti-ischaemics such as GTN infusion
• Refer to cath lab for urgent PCI if there are ongoing ECG changes or arrhythmias arise.

Question 7

What is the purpose of an invasive coronary angiogram?

Answer 7

• Establishes type of lesion + its location
• Entry through radial or femoral artery
• Visualisation of coronary arteries

Question 8

What is a percutaneous coronary intervention? (angioplasty w/stenting)

Answer 8

• Balloon coated with a stent introduced into affected coronary artery
• Balloon inflated, then deflated which leaves stent in place
• This leaves coronary artery wider than before, thus relieving occlusion

Question 9

What are the long term management options to control re-occurrences of acute coronary syndrome?

Answer 9

• Lifestyle changes (low fat, regular exercise, low salt)
• Dual antiplatelets for 12 months + aspirin for life
• Statins for low cholesterol
• ACE inhibits to control BP
• Bisoprolol to keep HR in check (around 70bpm)