Pathophysiology of Atheroma Flashcards
What is Atheroma?
Formation of focal elevated lesions (plaques) in intima of large and medium sized arteries
What does atheroma in coronary arteries cause?
Ischaemia
What is arteriosclerosis?
Age-related thickening, hardening and loss of elasticity in muscular arteries
What is the earliest significant lesion in atheroma?
A fatty streak
What is a fatty streak?
A yellow linear elevation of intimal lining comprised of masses of lipid-laden macrophages with no clinical significance
What can a fatty streak develop into?
Early atheromatous plaque
What is an early atheromatous plaque?
Smooth yellow patches in the intimal which is made of lipid-laden macrophages
What does an early atheromatous plaque develop into?
Established plaques
What is a fully developed atheromatous plaque?
Central lipid core with fibrous tissue cap, covered by arterial endothelium
What resides inside the fibrous cap of an atheromatous plaque?
Inflammatory cells recruited from arterial endothelium
What occurs in late stage plaque development?
Dystrophic calcification
Where do plaques form?
At arterial branching points (bifurcations)
What are the characteristics of a complicated atheroma?
Haemorrhage into the plaque
Plaque rupture
Thrombosis
What is the most important risk factor of atheroma?
Hypercholesterolaemia
What are the major signs of hyperlipidaemia?
Corneal arcus
Tendon xanthomata
Xanthelasmata
Biochemical evidence
What are the high risk factors of atheroma?
Smoking Hypertension Diabetes mellitus Male Elderly Accelerated process of plaque formation driven by lipids
What are the less strong risk factors of atheroma?
Obesity
Sedentary lifestyle
Low socio-economic status
Low birthweight
What are the two steps involved in the formation of atheromatous plaque?
- Injury to the endothelial lining of the artery
- Chronic inflammatory and healing response of vascular wall to agent causing injury
It is the chronic exposure of the arterial wall to these processes that cause the atheromatous plaque to form
What are the most important causes of endothelial injury in atheromatous plaque formation?
Haemodynamic disturbance
Hypercholesterolaemia
How does injury to the endothelial cells cause plaque formation?
There is a change to the endothelial cells functionally so there is enhanced expression of cell adhesion molecules. This causes high permeability for LDL and increased thrombogenicity
How do plaques grow?
The established plaques growth is initiated by small areas of endothelial loss
What is the clinical significance of atheroma?
Progressive lumen narrowing due to high grade plaque stenosis
Acute atherothrombotic occlusion
Embolisation of distal arterial bed
Ruptured atheromatous abdominal aortic aneurysm
What does an acute atherothrombotic occlusion cause?
Myocardial infarction
Stroke
Lower limb gangrene
What are the preventative and therapeutic approaches to atheroma?
Stop smoking Control blood pressure Weight-loss Regular exercise Dietary modifications
