13 Atheroma and embolism Flashcards
Define atherosclerosis:
Degeneration of arterial walls characterised by fibrosis, lipid deposition and inflammation which limits blood circulation and predisposes to thrombosis.
Which vessels are commonly affected by atherosclerosis? (5)
Abdominal aorta. Coronary arteries. Politeal arteries. Carotid vessels. Circle of Willis.
What are the common risk factors for atherosclerosis? (10)
Age, male, FH, genetic.
Hyperlipidaemia, high bp, smoking, diabetes, CRP, raised homocysteine.
How does an atherosclerotic plaque form?
Endothelial injury. Hyperlipidaemia causes lipid accumulation in intima. Monocytes migrate and become foam cells. FATTY STREAK. Chemokine secretion attracts immune cells and smooth muscle cells which secrete connective tissue.
What are the sequelae of atherosclerosis? (3)
Occlusion.
Weakening of vessel wall - aneurysm.
Erosion and thrombus.
Differentiate between a clot and a thrombus.
Clot: enzymatic, elastic, adopts vessel shape.
Thrombus: platelet dependant, firm.
What are platelets and what do they secrete? (4)
Megakaryocytic fragments.
Alpha granules: fibrinogen, fibronectin, PDGF.
Dense granules: chemotactic chemicals.
How does a arterial thrombus form?
Plaque rupture due to turbulence, collagen exposure. Platelets adhere and activate.
Which blood constituents predispose to venous thrombosis? (3)
Inflammatory mediators - infection, malignancy.
Factor V Leiden.
Oestrogen.
What are the sequelae of thrombosis? (5)
Vessel occlusion. Resolution. Incorporation into vessel wall. Recanalisation. Embolisation.
What are the effects of a pulmonary embolus?
Small: asymptomatic, pulmonary hypertension.
Medium: acute respiratory and cardiac failure.
Large: death (saddle emboli).
How do infective emboli occur?
What might they lead to?
Vegetations from infected heart valves.
Mycotic aneurysm formation.
How large do gas emboli have to be to have an effect?
Causes? (3)
> 100ml.
Obstetric procedures, chest wall injury, nitrogen decompression sickness.
When and how does an amniotic fluid embolism occur?
Histological signs?
Increased uterine pressure may force amniotic fluid into maternal uterine veins.
Shed skin cells.
Who gets foreign body emboli? What do they lead to?
IVDU’s e.g. talcum powder.
Granulomatous reaction.
