Ischemia & Infarction Flashcards
define acute ischemia
Sudden complete occlusion of an Artery
Define chronic ischemia
gradual incomplete arterial occlusion
Causes of Acute ischemia
- Thrombosis/embolism
- stranguation of intestinal vessels ( strangulated hernia, Voluolus, intussusception)
- Twisting of pedicle of an organ (ovarian cyst, testicular tumor)
- surgical ligature
- Ergot poisoning –> severe Arterio-spasm
effect of Acute ischemia
- poor collaterals –> infarction & (moist) gangrene
- Good collaterals –> No effect
Causes of Chronic ischemia
gradual:
* Atherosclerosis
* Arteritis (with endarteritis obliterans) as in syphilis
* Compression by tumor or enlarged lymph nodes
effect of Chronic ischemia
- poor collaterals/end artery: Ischemic Atrophy (+ fibrosis in myocardium in case of coronary athersclerosis)
- good collaterals: no effect
Define infarction
Area of Ischemic Necrosis due to sudden occlusion of Art. or vein
Infarction is divided into:
- red infarction
- pale white infarction
Red infarction occurs in what type of organs
Venous occlusion in:
* Soft & loose organs (lung)
* With dual circulation (lung,liver,intestine)
* previously congested –> sluggish venous outflow
what type of vessel is occluded in Red infarction
Veins
pale white infarction occurs in what type of organ
Arterial occlusion in:
* Less vascular organs
describe gross picture of Infarction
- Pyramidal shaped (apex towards occluded vessel)
- Margin shows Inflammation (hyperemia)
- shows coagulative necrosis (except CNS shows liquifactive necrosis)
all Infarction show Coagulative necrosis except infarctions of ____, they show ____
- CNS
- Liquifactive necrosis
Fate of Infarction
- Fibrosis
- Dystrophic calcification
- depression below surface of the organ
