What are the four steps of atherosclerosis development?
1. Endothelial cell injury 2. Migration of inflammatory cells 3. Lipid accumulation and SMC proliferation 4. Plaque structure
Describe how endothelial cell injury occurs
Factors such as smoking, high LDLs, or pressure from HTN instigate the inflammatory process causing monocyte and platelet adhesion, LDLs deposited in the intimal layer
Describe the migration of inflammatory cell stage
Monocytes migrate into the intima (becoming macrophages) and engulf lipoproteins
What happens during the lipid accumulation and SMC proliferation phase
Activated macrophages oxidize and ingest LDL, resulting in foam cell formation (primary component of atherosclerotic lesion). Macrophages instigate SMC proliferation and ECM elaboration which extends into lumen of vessel
Discuss the plaque structure and its complications
The fibrous cap (composed of SMC and ECM) is formed and a necrotic core/lipid pool composed of lipid-laden foam cells and fatty debris are contained beneath it. Lesion may be stable or vunerable dependant on thickness of cap, size of lipid pool, number of inflammatory and muscle cells
What is a complicated lesion?
An unstable or vulnerable plaque that can rupture, ulcerate, or erode leading to hemorrhage into the plaque or thrombotic occlusion of the vessel. This process can repeat itself. If thrombosis breaks off it becomes an emboli