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Pathophysiology of ischaemic heart disease

1. Progressive blockage by atherosclerosis
2. Clinical syndromes result from imbalance of oxygen supply and demand leading to inadequate myocardial perfusion
3. Plaque rupture + thrombosis leads to acute coronary syndromes

Management strategies

• Relief of ischaemia
• Prevent secondary injury

1. Initial treatment
   • Oxygen
   • Aspirin 75-300mg po
   • Morphine 5-10mg iv
   • Nitrates / GTN 1-5mg/hr
   • B-blockers
   • CCBlockers
2. ST segment elevation
   • Angioplasty +/- stenting if within 6 hours of chest pain 
3. Non-ST segment elevation ACS
   • Aspirin
   • Clopidogrel
   • unfractionated / low molecular weight heparin
4. Ongoing treatment / continuing ischaemia
   • Platelet gpIIb/IIa inhibitors (tirofiban, eptifibatide)
   • Early cardiac catheterisation

Indications for surgery

• Refractory angina
• Large amount of myocardium in ischaemic jeopardy

1. PCI not feasible
   • Tight Left main stem
   • Diffuse multivessel disease
   • Calcified coronaries
2. PCI unsuccessful
   • Inability to cross lesion

• LMS > 50%
• 3VD
• 2VD + LAD >70% stenosis

Contraindications to CABG

• Small distal targets

Consideration on Angiography

• Angiograms should not be more than 1 year old
• All stenoses >50% should be grafted if good distal run off
• If RCA is non-dominant it is not grafted
• If significant LMS disease; all major arteries distally need revascularisation

Other investigations

1. Cardiac echo: ?valvular heart disease
2. Carotid artery duplex: in those with previous stroke or TIA, or carotid bruits
3. Myocardial perfusion studies (a) determine if akinesis is due to irreversible dead myocardium or (b) hibernating or stunned myocardium in which bypass is indicated

Selection of Conduits