Pathophysiology Flashcards
What is the most important risk factor for atherosclerosis development?
Hypercholesterolaemia
What factors contribute to the development of atherosclerosis?
- Smoking
- Age
- Family history
- Alcohol
- Hypertension
- Diabetes mellitus
- Male
- Obesity/Sedentary lifestyle
- Low birthweight
Describe the first main step in the process of atherogenesis (i.e injury to the arterial wall)
- Endothelial injury and dysfunction - enhanced expression of cell adhesion molecules, increase in permeability for LDL, and increased thrombogenicity.
- Accumulation of LDL in vessel walls
- Monocyte adhesion to endothelium → migration into intima and transformation to foamy macrophages
- Platelet adhesion
- Factor release from activated platelets, macrophages → smooth muscle cell recruitment
Describe the second main process that occurs in atherogenesis (i.e tissue response to injurous agents)
- Following tissue injury and inflammation, there is a period of tissue repair - Growth factors stimulate smooth muscle proliferation, and deposition of collagen, elastin and mucopolysaccharides.
- Fibrous plaque - with lipid rich core.
- Plaque volume increases - Microthrombi form in the denuded areas of the plaque, which become organised.
What is a fatty streak?
This is a yellow linear elevation of the intimal lining, which comprises a mass of lipid laden macrophages.
These can disappear, but in patients who are at risk, they may progress to form atherosclerotic plaques.
When does the process of atherosclerosis start?
In childhood
What distinguishes an early athermatous plaque?
These are smooth yellow patches in the intima, full of lipid-laden macrophages, which progress to form established plaques.
What are the features of a fully deeloped athermatous plaque?
These are lesions with a central lipid core which have a fibrous tissue cap, which is covered by arterial endothelium.
The atheroma itself is soft, highly thrombogenic and often surrounded by a layer of foam cells.
Dystrophic calcification of the plaque can be extensive in late development.
Plaques often occur at arterial branching points where turbulence is highest. In later stages, plaques become confluent and cover large areas.
What are the components of atheromatous plaques?
- Fibrous cap
- Smooth muscle
- Macrophages/foam cells
- Lipid deposits
- Elastic lamina destruction
- Cholesterol
What are the different factors considered in Virkow’s triad?
- Vessel damage
- Hypercoagulability
- Stasis/flow through a vessel
How does a thrombus form?
- Endothelial injury -> atheroma -> altered lumenal shape
- Turbulent flow -> loss of intimal cells -> denuded plaque surface
- Platelets adhere to collagen -> activated -> fibrin attachment + RBC
- Thrombus proagates in direction of flow
What are the different types of emboli?
- Arterial
- Venous
- Fat
- Gas/Air
- Tumour
- Septic
- Amniotic fluid
- Bone marrow
- Foreign body
What are the main components of a venous thromboembolism?
Predominantly fibrin and red cells
What are the main components of an arterial thromboembolism?
Predominantly platelets and fibrin
What factors increase the risk of embolism formation?
- Cardiac failure
- Severe trauma/burns
- Post-op/post partum
- Nephrotic syndrome
- Disseminated malignancy
- COCP
- Age
- Immobilisation
- Obesity
- PMH of DVT
