Cardiovascular Flashcards
What are the 7 risk factors for atherosclerosis?
Age Smoking High serum cholesterol Obesity Diabetes Hypertension Family history
Where are atherosclerotic plaques found?
Peripheral or coronary arteries - Focal distribution along the artery length
What harm-dynamic factors govern atherosclerotic plaque distribution
Changes In flow and turbulence ie. at bifurcations causes artery to adjust wall thickness leading to neointima development
Describe the structural components of a atherosclerotic plaque
Lipid Necrotic core Connective tissue Fibrous cap lymphocytes
What happens if the atherosclerotic plaque occludes a vessel lumen
Restricts blood Flow (Angina)
What happens if an atherosclerotic plaque ruptures
Thrombus formation and death
What initiates the formation of an atherosclerotic plaque?
Injury to endothelial cells leading to endothelial dysfunction - this causes signals to be sent to circulating leukocytes which accumulate and migrate into vessel wall
What stimuli cause inflammation in the arterial wall?
- LDL passing in and out of arterial wall in excess, accumulate in arterial wall and undergo oxidation and glyceration
- Endothelial dysfunction in response to injury hypothesis
What is the role of chemoattractants in the formation of atherosclerotic plaque?
Once released from the endothelium, They attract leukocytes through chemotaxis - concentration gradient is created which drives the movement of cells
Which inflammatory cytokines can be found in atherosclerotic plaques
IL-1 IL-6 IL-8 IFN-y (Proinflammatory agent) TGF-B Monocyte Chemoattractive Protein-1
What are the 4 stages of atherosclerosis?
- Fatty streak formation
- Intermediate lesion
- Fibrous plaque or advanced lesion
- Plaque rupture
At what age do fatty streaks begin to form
<10 years
What does a fatty streak consist of?
Aggregations of lipid laden macrophages and T lymphocytes within the intimal layer of the vessel wall
What are the layers of an intermediate lesion
Foam cells Vascular smooth muscle cells T-lymphocytes Adhesion and aggregation of platelets to vessel wall Isolated pools of extracellular lipid
What are the 4 steps of the adhesion cascade
- Capture
- Rolling - slows cell down for adherence
- Adhesion
- Transmigration
What mediates the capture and rolling stage of the adhesion cascade?
Selectins
What mediates the adhesion and transmigration stages of the adhesion cascade
Integrins and chemoattractants
What are the main concerns with fibrous plaques and advanced lesions?
They made impede blood flow or be prone to rupture
Which cells secrete the fibrous cap that covers fibrous plaques
Smooth muscle cells that overlie the lipid core and the necrotic debris
What does a fibrous plaque contain?
Smooth muscle cells, macrophages, foam cells and T-lymphocytes
What does the dense fibrous cap on a fibrous plaque contain
ECM proteins including collagen (Strength) and elastin (Flexibility)
What occurs in order for a plaque to rupture
If the balance is shifted in favour of inflammatory conditions such as increased enzyme activity that causes the cap to become weak hence the cap ruptures
What is the result of plaque rupture?
Thrombus formation and vessel occlusion
What is the treatment for coronary artery disease?
Percutaneous coronary intervention