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Questions and Answers
What is the primary consequence of systemic embolization?
Where do the majority of venous emboli originate from?
What is a common complication of a large pulmonary embolism?
Which type of emboli primarily leads to ischemic infarction in the lungs?
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What percentage of systemic emboli arises from intracardiac mural thrombi?
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Which area is a common site for systemic embolization?
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What is a potential cause of fat embolism?
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Which vascular segment is primarily affected by venous thromboemboli?
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What is a significant characteristic of fat embolism syndrome?
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What mechanism primarily contributes to the pathogenesis of fat embolism syndrome?
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What is the most common cause of maternal death in developed countries?
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Which of the following is NOT typically involved in air embolism pathology?
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What type of necrosis is caused by the occlusion of vascular supply leading to an infarct?
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Which of the following is a less common cause of arterial obstruction leading to infarction?
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What defines the morphology of an infarct?
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What is a possible consequence of sufficient air entering the pulmonary circulation?
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Which type of infarct is characterized by hemorrhage?
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What type of infarct occurs with arterial occlusions in organs with end-arterial circulations?
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Which histologic finding is typically associated with infarcts?
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What influences the likelihood of tissue infarction under occlusion?
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Which factor contributes to the development of a septic infarct?
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Which tissue is notably vulnerable to irreversible damage due to ischemia after only 3 to 4 minutes?
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Which of the following cases could lead to a red infarct?
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What type of necrosis occurs as a result of ischemic injury in the central nervous system?
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Study Notes
Embolism
- An embolus is a mass carried by blood to a location different than its point of origin.
- The majority of emboli originate from a dislodged blood clot.
- Embolism results in partial or complete vessel blockage.
- Embolism primarily causes tissue death (infarction) in downstream tissues.
- Over 95% of venous emboli originate in the deep leg veins.
- Emboli travel through the heart and usually lodge in the pulmonary vessels.
- Emboli can block the main pulmonary artery, bifurcate the right and left pulmonary arteries, or pass into smaller arterioles.
- 60% to 80% of pulmonary emboli are small and clinically silent.
- Large emboli can cause sudden death or pulmonary hemorrhage.
- Small emboli cause infarction.
Systemic Thromboembolism
- 80% of systemic emboli originate from heart wall blood clots.
- Two-thirds are associated with left ventricular infarcts.
- Other origins include dilated left atria, aortic aneurysms, and thrombi over ulcerated plaques.
- Systemic emboli commonly lodge in the lower extremities (75%) and the central nervous system (10%).
- The severity of consequences depends on vessel size, collateral blood flow, and tissue vulnerability.
- Fat embolism is released from injury or bone fracture.
- Fat embolism syndrome causes pulmonary insufficiency, neurological symptoms, anemia, and petechial rash.
- Fat embolism syndrome is fatal in 10% of cases.
- Fat emboli cause mechanical obstruction and biochemical injury due to fatty acid release.
- Amniotic fluid embolism occurs during labor or postpartum.
- Amniotic fluid embolism is a serious complication with an 80% mortality rate.
- Symptoms include dyspnea, cyanosis, shock, seizures, and coma.
- Amniotic fluid enters the maternal circulation through tears in the placenta or uterine vein rupture.
- Air embolism can occur when air bubbles enter the circulation and obstruct blood flow.
- Small air emboli are usually harmless.
- Large emboli can cause hypoxia or death.
Infarction
- An infarct is a region of ischemic necrosis caused by vascular occlusion.
- Most infarctions are caused by arterial thrombosis or embolism.
- Other causes include vasospasm, atheroma expansion, vessel compression, vessel twisting, or entrapment in a hernia sac.
- Infarcts are classified as red (hemorrhagic) or white (anemic) based on bleeding.
- Infarcts can be septic (infected) or bland (not infected).
Red Infarcts
- Occur in venous occlusions, tissues with dual circulations, congested tissues, or after re-established blood flow.
White Infarcts
- Occur in organs with end-arterial circulation (heart, spleen, kidney).
- Infarcts are wedge-shaped with the occluded vessel at the apex.
- Ischemic coagulative necrosis is the main histologic finding.
- Inflammation occurs within hours and well-defined within 1 to 2 days.
- Repair occurs through regeneration or scar formation.
- The brain experiences liquefactive necrosis instead of coagulative necrosis.
- Septic infarcts occur when infected emboli or microbes seed necrotic tissue.
Factors Influencing Infarct Development
- Tissue vulnerability to ischemia: Neurons are most vulnerable, followed by myocardial cells.
- Rate of occlusion: Slow occlusions allow time for collateral blood supply development.
- Anatomy of vascular supply: Dual circulation tissues (lung, liver, intestines) are less vulnerable.
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Description
This quiz covers the fundamental concepts of embolism and systemic thromboembolism. Learn about the origins, consequences, and clinical significance of emboli in the human body. Test your knowledge on how these conditions affect vascular health and the potential outcomes of embolic events.
