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EMS - Mechanisms of disease > Atheroma and thrombosis > Flashcards

Atheroma and thrombosis Flashcards

1
Q

What is atherosclerosis?

A

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

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2
Q

What are the common risk factors for atherosclerosis?

A

Male sex

Post-menopausal women

Hyperlipidaemia (m)

Hypertension (m)

Diabetes (m)

Smoking (m)

Genetic

Other: CRP, increased homocystiene (m)

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3
Q

Describe the pathophysiology underlying atherosclerosis.

A
  • Arises due to chronic injury and repair of the endothelium
  • First step: endothelial injury
  • Causes: haemodynamic injury, chemicals, immune complex deposition, irradiatio
  • In the presence of hyperlipidaemia lipid will accumulate in the inner most part of the vessel (the “intima”)
  • Monocytes will migrate into the intima (due to lipid and endothelial injury (VCAM1)) and ingest the lipid becoming foam cells
  • This stage is a FATTY STREAK
  • The “foam cells” are secrete chemokines attracting more monocytes/macrophages, lymphocytes and smooth muscle cells
  • Smooth cells proliferate and secrete connective tissue
  • This mixture of fat, extracellular material and leukocytes and smooth muscle form the atherosclerotic plaque
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4
Q

What are the potential sequelae of atherosclerosis?

A
  • Occlusion
  • Weakening of the vessel walls - aneurysm formation
  • Erosion
  • Haemmorhage
  • Embolus
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5
Q

What is an embolus?

A
  • A mass of material in the vascular system able to lodge in a vessel and block it
  • May be endo- or exogenous
  • May be solid, liquid or gas
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6
Q
A
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7
Q

What is a thrombosis?

A

•Solidification of blood contents formed in the vessel during life

Different from a clot in both pathogenesis and morphology. Clot elastic, soft and conforms to vessel body wall. Thrombus firm.

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8
Q

What is the role of platelets in thrombosis?

A

•Bind to collagen exposed by endothelial damage and become activated
•Secrete
–Alpha granules: fibrinogen, fibronectin, PDGF
–Dense granules: chemotactic chemicals

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9
Q

What is Virchow’s triad?

A
  • Platelet adhesion and subsequent thrombus formation requires changes in……
  • The intimal surface of the vessel
  • The pattern of blood flow
  • Blood constituents
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10
Q

What are the features of venous thrombosis?

A

Intimal change - valves

Change in blood flow - immobile

Change in blood constituents - eostrogen, toxins from smoking

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11
Q

What is a paradoxical embolus?

A

Embolus formed on left side of heart and crosses defect in septum to right??

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12
Q

What are the acquired risk factors for thrombosis?

A

Immobility

Malignancy

Previous VTE

Heart failure

Eostrogens

Obesity

Pregnancy

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13
Q

Where do systemic thrombi usually arise?

A

The heart

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14
Q

What is the most common site of origin for pulmonary emboli?

A

Deep leg veins

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15
Q

What is the gold standard diagnostic test from PE?

A

CTPA

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16
Q

What are infective emboli?

A

Usually from the vegetations on infected heart valves
Effects compounded by the infective nature – may lead to mycotic aneurysm formation

Common in IVDU and those with artificial heart valves.

17
Q

What is a tumour embolus?

A
  • Bits may break off as tumours penetrate vessels
  • Do not usually cause immediate physical problems
  • Major route of dissemination
18
Q

What are gas emboli?

A

•Air (vessel opened into the air)
–Obstetric procedures / chest wall injury
–>100ml to cause clinical effects

•Nitrogen
–Decompression sickness (“the bends”)
–Divers, tunnel workers
–Nitrogen bubbles enter bones, joints and lungs

19
Q

What are the features of the amniotic fluid emboli?

A
  • Increased uterine pressure during labour may force AF into maternal uterine veins (1:50,000 deliveries)
  • Lodge in lungs à respiratory distress
  • Can see shed skin cells histologically
20
Q

What are the features of fat emboli?

A
  • Microscopic fat emboli found in 90% patients with significant trauma
  • Sudden onset of respiratory distress
  • Fatal in 10%
21
Q

What are the features of foreign body emboli?

A
  • Particles injected intravenously
  • E.g. talc in IVDU’s
  • Leads to a granulomatous reaction

EMS - Mechanisms of disease (21 decks)

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