16. Ischaemia and Infarction Flashcards

1
Q

What is ischaemia?

A

Lack of blood supply

Leads to lack O2 and nutrition and build up of waste

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2
Q

What factors determine how susceptible a tissue is to ischaemia?

A

Poor blood supply
Collateral circulation (is there a bypass)
Metabolic rate
‘Watershed’ areas

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3
Q

Which organs have good collateral circulation?

A

Liver
Lung
Bowel
Brain

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4
Q

Which organs don’t have collateral circulation?

A

Kidney
Spleen
Heart

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5
Q

What areas of the body are considered watershed areas?

A

Splenic flexure of the colon
Anterior/middle cerebral
Deep myocardium

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6
Q

What is reperfusion injury?

A

Blood supply restoration after a loss can cause an increase of tissue damage

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7
Q

What mechanisms cause reperfusion injury?

A

Free radicals are formed

Ca++ ATPase failure increases Ca++ in cytosol (cell death)

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8
Q

What drugs are given after cerebral and myocardial infarcts to prevent reperfusion injury?

A

Ca++ channel blockers

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9
Q

What is infarction?

A

Area of ischaemic necrosis caused by occlusion of an artery or vein

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10
Q

What are the causes of ischaemia and infarction?

A
Shock
Obstruction to a vessel
Vasculitis
Compression or torsion of a vessel
Local vasospasm
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11
Q

What is a thrombosis?

A

Solid mass in flowing blood

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12
Q

What is an embolus?

A

Solid/liquid/gas that moves from one part of circulation to another

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13
Q

What is the presentation of stercoral ulceration of retrosigmoid colon?

A

Chronic constipation

Faeces closes off blood vessels in bowel wall

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14
Q

How does an area of infarct look early on?

A

Irregular

Hyperaemia at edges due to inflammation

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15
Q

How does late infarct look like in solid organs?

A

White due to low haemosiderin pigment

Pale and defined

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16
Q

How does late infarct look like in spongy organs?

A

Red (high haemosiderin)

Firm

17
Q

Why should care be taken when giving anticoagulants in brain infarct due to an embolus?

A

Vessel wall might also become ischaemic and rupture and then it’ll bleed everywhere and won’t be fun

18
Q

What consequence does scarring of the myocardium have?

A

Loss of muscle pump function

LV failure