Atheroma, thrombosis, embolism and infarction Flashcards
What is an atheroma?
Fibro-fatty plaques
(porridge-like tumour)
Refers to plaques found particularly in elastic and medium-to-large muscular arteries
What is atherosclerosis?
Porridge-like hardness
The consequence of atheroma
What is arteriosclerosis?
Hardening of the arteries
Atheroma is one cause
Other causes include age-related sclerosis an calcification
Risk factors of atheroma
Age Male sex Genetics Hyperlipidaemia Hypertension Smoking Diabetes mellitus
Describe the pathogenesis of atheroma
Chronic endothelial injury/dysfunction
Accumulation of intimal lipid and foamy macrophages
Smooth muscle proliferation
Fibrosis forming a fibro-lipid plaque
Plaque injury- thrombosis and haemorrhage
What is the difference between a complicated and uncomplicated plaque?
Uncomplicated= thin fibrous cap Complicated= superimposed thrombi due to ulceration of thin cap= haemorrhage
Where do atheroma’s occur?
Elastic and medium-to-large muscular arteries
- Abdominal aorta
- Coronary arteries
- Popliteal arteries
- Descending thoracic aorta
- Internal carotid arteries
- Vessels of the circle of Willis (base of the brain)
What are the complications of atheroma?
Calcification Ulceration Plaque rupture Haemorrhage Thrombosis Aneurysmal dilation
What do the complications of atheroma lead to?
Vessel obstruction and downstream ischaemia
External vessel rupture may also occur, particularly with abdominal aortic aneurysms
What are the clinical implications of atheroma?
Cerebral infarction
Emboli in carotid arteries= TIA/ cerebral infarction
Myocardial infarction, cardiac failure
Aneurysm rupture causes sudden death
Peripheral vascular disease with intermittent claudication- thigh (impairment of walking)
Gangrene
What is a thrombus?
Solidification of blood constituents that forms within the vascular system during life
What is the difference between thrombus and blood clot?
Pathological process- denotes formation of thrombus within uninterrupted vascular system
Solidification of blood constituents outside the vascular system or after death is termed blood clot or haematoma (particularly if formed within tissues)
What are the risk factors for thrombosis?
Endothelial injury
Abnormal blood flow
Hypercoagulability
(Virchow’s Triad)
Describe endothelial injury
Ulcerated atheromatous plaques (aorta, carotid arteries, iliac and femoral arteries, coronary arteries)
Left ventricular endocardium after myocardial infarction
Abnormal cardiac valves (rheumatic fever, infective endocarditis, prosthetic valves)
Describe abnormal blood flow
Disrupts laminar flow
Prevents dilution of clotting factors
Retards the inflow of inhibitors of clotting factors
Promotes endothelial cell activation
What is turbulence?
Contributes to the development of arterial and cardiac thrombi
What is stasis?
Important in the formation of venous thrombi
Describe hypercoagulability
Alteration of the blood coagulation mechanism (particularly platelets and the clotting cascade) that in some way predisposes to thrombosis
May be a genetic predisposition (protein S/C deficiency)
May be acquired (after surgical procedures)
What are the types of thrombi?
Mural
Arterial
Venous