Embolus

An embolus (

The term is distinct from embolism and thromboembolism, which may be consequences of an embolus, as discussed below.^[3]

The term was coined in 1848 by Rudolf Virchow as part of his foundational research into blood clots.^[4][5]

Nomenclature

The term embolus refers generally to any free-floating mass in the bloodstream. A related term is embolism, which describes the phenomenon of an embolus lodging in a vessel and creating a blockage.^[2] An embolism is technically a consequence of an embolus, but the terms are sometimes used interchangeably.^[6] Both emboli and embolisms are usually named according to their composite substance.^{[citation needed]}

In contrast to emboli, which can cause occlusion at sites distant from their points of origin, there are also non-traveling blockages that develop locally from vascular trauma and inflammation or other epithelial pathology, such as atheromata and thrombi. If these local blockages dislodge into circulation, they become emboli and if not broken down during circulation, may cause embolism(s).^[3] For example, a thromboembolism is the result of a thrombus that has broken off the interior of a blood vessel and caused a vessel blockage elsewhere in the circulation.

Details of embolism classification are discussed below.

Classification by substance

The physical composition of the embolic material is the defining feature for classification, and this composition reflects the underlying pathophysiologic mechanism of the embolus' formation. Furthermore, different types of emboli result in different types of embolisms, each with distinct clinical characteristics.

In thromboembolism, the thrombus (blood clot) from a blood vessel is completely or partially detached from the site of thrombosis (clot). The blood flow will then carry the embolus (via blood vessels) to various parts of the body where it can block the lumen (vessel cavity) and cause vessel obstruction or occlusion. The free-moving thrombus is called an embolus.^[7] A thrombus is always attached to the vessel wall and is never freely moving in the blood circulation. This is also the key difference for pathologists to determine the cause of a blood clot, either by thrombosis or by post-mortem blood clot. Vessel obstruction will then lead to different pathological issues such as blood stasis and ischemia. However, not only thromboembolism will cause the obstruction of blood flow in vessels, but also any kind of embolism is capable of causing the same problem.

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An

iatrogenic

error in modern medicine is extremely rare).

Henry's Law

in physical chemistry.

Embolism by other materials is rare.

Amniotic-fluid embolism

is a rare complication of childbirth.

Clinical significance

Emboli are clinically significant for their capacity to cause embolisms, which are a major cause of morbidity and mortality.^[9][10] By themselves, emboli are pathologic and therefore indicate some underlying dysfunction.

It may be difficult in the clinical setting to differentiate a thrombotic event (i.e., a local clot at the site of symptoms) from an embolic event (i.e., local obstruction due to a free-floating mass that traveled through circulation from elsewhere in the body).

Septic emboli may also be a contributor to spreading infection through the bloodstream to other tissues.^[11]

History

Rudolf Virchow, the German physician and "father of pathology", is generally credited with the first explanation of the relationship between thrombi, emboli, and embolisms. He coined the terms embolism (initially called "Embolia") and thrombosis while proposing a hypothesis for the pathophysiology of pulmonary thromboembolism.^[5][12]

In his work, he described the consequences of thrombosis and the factors leading thereto, a concept which today is known as Virchow's Triad. However, there is some dispute regarding certain aspects of this attribution.^[13]

See also

• Paradoxical embolism
• Pulmonary embolism
• Virchow's Triad

References

1. ^ "embolus". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
2. ^ ^{a b} Kumar V.; Abbas A.K.; Fausto N. Pathologic Basis of Disease.
3. ^ ^{a b} "Medical Definition of Embolus". Archived from the original on 2014-07-14. Retrieved 2010-10-10.
4. ISBN 0-671-62130-0
   .
5. ^
   OCLC 37534011.{{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link
   )
6. ^ "Arterial embolism: MedlinePlus Medical Encyclopedia". medlineplus.gov. Retrieved 2020-12-09.
7. ISBN 0-7817-4118-1
   .
8. PMID 21215588
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9. PMID 31340984
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10. S2CID 242392407
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11. PMID 31751017
    , retrieved 2022-11-08
12. PMID 20739582
    .
13. PMID 15455989
    .