13 Atheroma and embolism Flashcards Preview

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Flashcards in 13 Atheroma and embolism Deck (15)
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1
Q

Define atherosclerosis:

A

Degeneration of arterial walls characterised by fibrosis, lipid deposition and inflammation which limits blood circulation and predisposes to thrombosis.

2
Q

Which vessels are commonly affected by atherosclerosis? (5)

A
Abdominal aorta.
Coronary arteries.
Politeal arteries.
Carotid vessels.
Circle of Willis.
3
Q

What are the common risk factors for atherosclerosis? (10)

A

Age, male, FH, genetic.

Hyperlipidaemia, high bp, smoking, diabetes, CRP, raised homocysteine.

4
Q

How does an atherosclerotic plaque form?

A

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.

5
Q

What are the sequelae of atherosclerosis? (3)

A

Occlusion.
Weakening of vessel wall - aneurysm.
Erosion and thrombus.

6
Q

Differentiate between a clot and a thrombus.

A

Clot: enzymatic, elastic, adopts vessel shape.
Thrombus: platelet dependant, firm.

7
Q

What are platelets and what do they secrete? (4)

A

Megakaryocytic fragments.
Alpha granules: fibrinogen, fibronectin, PDGF.
Dense granules: chemotactic chemicals.

8
Q

How does a arterial thrombus form?

A

Plaque rupture due to turbulence, collagen exposure. Platelets adhere and activate.

9
Q

Which blood constituents predispose to venous thrombosis? (3)

A

Inflammatory mediators - infection, malignancy.
Factor V Leiden.
Oestrogen.

10
Q

What are the sequelae of thrombosis? (5)

A
Vessel occlusion.
Resolution.
Incorporation into vessel wall.
Recanalisation.
Embolisation.
11
Q

What are the effects of a pulmonary embolus?

A

Small: asymptomatic, pulmonary hypertension.
Medium: acute respiratory and cardiac failure.
Large: death (saddle emboli).

12
Q

How do infective emboli occur?

What might they lead to?

A

Vegetations from infected heart valves.

Mycotic aneurysm formation.

13
Q

How large do gas emboli have to be to have an effect?

Causes? (3)

A

> 100ml.

Obstetric procedures, chest wall injury, nitrogen decompression sickness.

14
Q

When and how does an amniotic fluid embolism occur?

Histological signs?

A

Increased uterine pressure may force amniotic fluid into maternal uterine veins.
Shed skin cells.

15
Q

Who gets foreign body emboli? What do they lead to?

A

IVDU’s e.g. talcum powder.

Granulomatous reaction.