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Cardiovascular > Ischemia and Infarction - Physiology > Flashcards

Ischemia and Infarction - Physiology Flashcards

1
Q

Define ischemia

A

Lack of blood supply to tissue/organ = hypoxia

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2
Q

What are the 4 different types of blood/O2 abnormal perfusion

A

Hypoxic = low inspired O2. Can also have norm O2 but low paO2

Anaemic = Norm inspired O2 but blood abnormal

Stagnant = Norm inspired O2 but abnormal delivery either: a) Local eg Occlusion or 2) Systemic eg: shock

Cytotoxic = Norm inspired O2 but abnormal at tissue level

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3
Q

What are some blood supply issues?

A 
Coronary artery atheroma 
Cardiac failure
Anaemia
Pulm function
Previous MI
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4
Q

Does the heart have a high or low intrinsic demand?

A

High

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5
Q

What are the different types of atherosclerosis?

A

Established atheroma in coronary a = stable angina
Complicated atheroma in coronary a = unstable angina
Ulcerated/fissured plaque -> thrombosis -> ischaemia/infarction
Atheroma in aorta -> aneurysm

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6
Q

What are some consequences of ischaemia

A 
MI
TIA 
PVD 
Cerebral infarction
Aortic aneurysm 
Cardiac failure
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7
Q

What are the effects of ischaemia functionally?

A

Blood/O2 feels to meet demand due to decreased supply or increased demand or both

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8
Q

What are the effects of ischaemia biochemically?

A

Anaerobic metabolism causes increase lactic acid so leads to cell death

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9
Q

Define what infarction is?

A

Ischemic necrosis due to occlusion of either arterial or venous vessels

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10
Q

What can result in caessation of blood flow for infarction?

A

Thrombosis
Embolism
Trauma - cut or ruptured vessel
Enstrangulation eg; gut

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11
Q

Which factors can determine the damage scale for infarction?

A

Time peroid
Pattern of blood supply
Tissue/organ
Previous disease

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12
Q

What are the 2 types of necrosis?

A

Coagulative necrosis eg: heart, lung
Colliquitive necrosis eg: brain

Just to note; anaerobic metabolism -> cell death -> liberation of enzymes -> breakdown of tissue

Coronary arterial obstruction -> decrease blood flow to region of myocardium -> ischaemia, rapid myocardial dysfunction -> myocyte death

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13
Q

What are the different myocardial ischemia onset times?

A

Anaerobic metabolism onset of atop depletion = seconds

Loss of myocardial contractility (-> heart failure) = <2min

Ultrastructural changes = few min

*Severe ischemia = 20-30min = irreversible damage

Myocyte necrosis ( leakage of macromolecules ) = 20-40mins

Injury to microvascular = >1 hour

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14
Q

Describe the appearance of an infarct less than 24hour?

A

No change on visual inspection

Few-12hours = swollen mitochondria

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15
Q

Describe the appearance of an infarct between 24-48h

A

Pale infarct and solid tissue: eg myocardium, spleen and kidney

Red infarct and loose tissue ( previously congested tissue, venous occlusion ) eg: lung and liver

Microscopically = acute inflammation initially at edge of infarct ~ loss of specialised cell features

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16
Q

What is the infarct appearance after 72hours?

A

Macroscopic:

  • Pale infarct: yellow/white and red periphery
  • Red infarct: little change

Microscopic:

  • Chronic inflam
  • Macroscopic remove debris
  • Granulation tissue
  • Fibrosis
17
Q

What is the appearance of an infarct at the end/end result?

A

Scar replaces area of tissue damage
Shape depends on territory of occluded vessel
Reperfusion Injury

18
Q

What is the infarct factors onset for between 4-12hours?

A

Early coagulation necrosis
Oedema
Hemorrhage

19
Q

What is the infarct factors onset for between 12-24h?

A

Ongoing coagulation necrosis
Myocyte changes
Early neutrophillic infiltrate

20
Q

What is the infarct factors onset for between 1-3days?

A

Coagulation necrosis
Loss of nuclei + striations
Brisk neutrophilic infiltrate

21
Q

What is the infarct factors onset for between 3-7days?

A

Disintegration of dead myofibres
Dying neutrophils
Early phagocytosis

22
Q

What is the infarct factors onset for between 7-10days?

A

Well developed phagocytosis

Granulation tissue at margins

23
Q

What is the infarct factors onset for between 10-14 days?

A

Well established granulation tissue with new blood vessels and collagen deposition

24
Q

What is the infarct factors onset for between 2-8weeks?

A

Increased collagen deposition

Decreased cellularity

25
Q

What is the infarct factors onset for between >2 months?

A

Dense collagenous scar

26
Q

What are the two types of infarcts?

A

Transmural: ischaemic necrosis affects full thickness of myocardium
Subendocardial:
Ischemic necrosis limited to zone of myocardium under endocardial lining

27
Q

Which infarct classification can NSTEMI correlate with?

A

Subendocardial

28
Q

What are complications associated with infarction?

A 
DARTH VADER
Death
Arrhythmias
Rupture 
Tamponade 
Heart failure 
Valve disease
Aneurysm 
Dresslers syndrome 
thromboEmbolism
Regurg

Cardiovascular (34 decks)

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