infarction

• Infarction is an area of ischemic necrosis caused by occlusion of either the arterial supply or the venous drainage
• Tissue infarction is a common and extremely important cause of clinical illness
• Infarcts are classified according to color and the presence or absence of infection; they are either red (hemorrhagic) or white (anemic) infarcts and may be septic or bland
• White infarcts occur with arterial occlusions in solid organs with end-arterial circulation like the heart, spleen, and kidney
• Red infarcts occur in loose, spongy tissues like the lung, in tissues with dual circulations, in tissues previously congested by sluggish venous outflow, and when flow is reestablished to a site of previous arterial occlusion and necrosis
• Septic infarctions occur when infected cardiac valve vegetations embolize or when microbes seed necrotic tissue, leading to the conversion of the infarct to an abscess with a greater inflammatory response
• Tissue infarction is a common and important cause of clinical illness, with most cardiovascular diseases attributable to myocardial or cerebral infarction
• Arterial thrombosis or arterial embolism underlies the vast majority of infarctions
• Factors influencing the development of an infarct includes:

  1. anatomy of the vascular supply
  2. rate of occlusion
  3. tissue vulnerability to hypoxia
  4. hypoxemia