Myocardial ischaemic occur when there is imbalance between O2 supply and myocardial and myocardial demand.
Can be due to
1) Mechanical obstruction
- Atheroma
- Thrombosis
- Spasm
- Embolus
- Coronary ostial stenosis
- Coronary arteritis
2) Decrease blood flow of oxygenated blood to myocardium
- Anaemia
- Carboxyhaemoglobulinaemia
- Hypotension leads to decrease coronary perfusion pressure.
3) Increase demand of O2
- Increase cardiac input in thyrotoxicosis
- Myocardial hypertrophy (aortic stenosis@ hypertension)
The most common causes for IHD is Coronary artery disease (CAD) due to coronary atherosclerosis.
Mechanism responsible for thrombosis on plaque
1) Superficial endothelial injury
- Break of endothelial lining
- Platelet adhesion
- Migration of smooth muscle from tunica media to intima
- Formation of form cell
- Thrombus formation.
2) Deep endothelial fissuring
- Advanced plaque with lipid core
- Tearing of plaque cap allows entering of blood from lumen into plaque itself
- Core with lamellar lipid surface, tissue fator produced by amcrophage + exposed collegen highly thrombogenic
- Formation of thrombus and expendation of thrombus
- Thrombus extends into lumen.
No comments:
Post a Comment