Define atheroma
Accum of IC & EC lipids in intima and media of large n medium sized arteries
Define atherosclerosis
Thickening n hardening of artery walls bc atheroma
Define arteriosclerosis
Thickening n hardening or artery/arteriole walls bc hypertension / diabetes
What are the 5 cellular events leading to Atherosclerosis?
- Chronic Endothelial Injury
- Endothelial Dysfunction (platelet adhesion / PDGF release) (Monocye accum in intima)
- SMC emigrate from media –> intima
- MAC + SMC engulf accum oxidised lipid –> Foam Cells
- SMC prolif in response to cytokines / GF
What is the Macroscopic appearance of atherosclerosis?
Plaque
In elastic arteries (aorta / carotid / iliac)
In large / medium sized muscular arteries (coronary / popliteal)
What are the 3 stages of plaque dev?
- Fatty streak
- Simple plaque
- Complicated plaque
Describe the Fatty Streak stage of plaque dev
Lipid deposition in intima
Yellow / slightly raised
No blood flow disturbance
Describe the Simple Plaque stage of plaque dev
Yellow / White / Raised
Around ostia
Turbulent blood flow
Enlarge + coalesce
Describe the Complicated Plaque stage of plaque dev
Calcification
Thrombosis
Haemorrhage into plaque
In aorta: weak walls / aneurysm forms (bulge in vessel)
What is the Early Microscopic appearance of atherosclerosis?
Foam cell accum
SMC prolif
EC lipid depos
What is the Later Microscopic appearance of atherosclerosis?
Fibrosis
Necrosis
Damaged extended to media
Plaque fissuring (cracking) n rupture
What are the effects of atherosclerosis?
- IHD (bc reduced blood flow to myocardium)
- Cerebral Ischaemia (TIA / Stroke)
- Abdominal Aortic Aneurysm (AAA)
- Peripheral Vasc Disease
- Mesenteric Ischaemia (small intestines)
How does a Cerebral Infarction (stroke) happen?
- Atherosclerosis of Carotid Arteries
- Thrombus forms over plaque
- Thromboembolism to Cerebral Arteries
How does an AAA happen?
- Local dilation bc weakened wall
- Arteries filled by thrombus
- Can rupture / prod. emboli
What cells are involved in atherogenesis?
- Endothelial cells
- Platelets
- SMC
- MAC
What is the role of endothelial cells in atherogenesis?
Haemostasis
Collagen secretion
Stim SMC prolif + migration
What is the role of platelets in atherogenesis?
Haemostasis
PDGF stim SMC prolif + migration
What is the role of SMC in atherogenesis?
Take up LDL –> Foam Cells
Collagen synth
What is the role of MAC in atherogenesis?
Oxidise LDL
Take up LDL –> Foam Cells
Stim SMC prolif + migration
What causes atherogenesis?
Endothelial injury (too much LDL / toxins / hypertension)
What does endothelial injury cause in atherogenesis?
- Platelet adhesion / PDGF release –> SMC prolif + migration
- LDL oxidation + uptake by SMC + MAC
- Monocyte migration –> intima
- Local Thrombosis
What do Foam Cells secrete and what does that cause?
Cytokines
Causes further SMC stim
Inflamm cell recruitment
What are the risk factors of atherosclerosis?
Smoking Alcohol Hypertension Familial Hyperlipidaemia Obesity
How can you prevent atherosclerosis?
Stop smoking Exercise Treat hypertension Aspirin Statins
