Ischaemic heart disease (IHD) occurs when there is an imbalance between oxygen supply and myocardial demand. >90% are due to reduced coronary blood flow. This can result in angina and/or acute coronary syndrome.
Heart disease accounts for 40% of all mortality in developed countries. IHD is the biggest contributor to cardiac mortality.
The right and left coronary arteries arise immediately distal to the aortic valve (aortic sinuses). They initially run in the atrioventricular groove on either side of the pulmonary trunk before giving off branches. It is mostly an end artery system, so blockage of a vessel would lead to myocardial infarction.
The left coronary artery supplies the left atrium, left ventricle and interventricular septum; it divides into the left anterior descending and circumflex arteries.
The right coronary artery provides the posterior interventricular and marginal branches. It supplies the right atrium, right ventricle and the conduction systems. Therefore, occlusion of this vessel may produce heart block.
Most cases of ischaemic heart disease occur because of atherosclerosis.
Rarer causes include:
- Embolism: endocarditis, prosthetic valve embolus
- Coronary artery wall thickening: amyloidosis
- Coronary spasm: cocaine-induced
- Congenital arterial disease: arteriovenous fistula
- Family history
- Stop smoking
- Weight loss
- Aerobic exercise
- Avoid excessive alcohol consumption
- ACE inhibitors
Factors in oxygen supply and demand
- Thrombus formation on fissured atheromatous plaque
- Carbon monoxide poisoning
- Aortic stenosis
- Hypertrophic cardiomyopathy