Embolus
Encyclopedia
An embolus is any detached, itinerant intravascular mass (solid, liquid, or gaseous) carried by circulation
, which is capable of clogging arterial capillary beds (create an arterial occlusion
) at a site distant from its point of origin.
By contrast there are non-traveling blockages that develop locally from vascular trauma or epithelial pathology and vascular inflammation
— like atheroma
, thrombi
. However, if a thrombus breaks loose from its genesis site it becomes a thrombo-embolus and if not broken down during transit, may cause embolism
(s).
The term was coined in 1848 by Rudolf Virchow
.
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. Note that the free-moving thrombus is called an embolus. 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.
Fat embolism
usually occurs when endogenous (from sources within the organism) fat tissue escapes into the blood circulation. The usual cause of fat embolism is therefore the fracture
of tubular bones (such as the femur
), which will lead to the leakage of fat tissue within the bone marrow into ruptured vessels. There are also exogenous (from sources of external origin) causes such as intravenous injection of emulsions.
An air embolism
, on the other hand, is usually always caused by exogenic factors. This can be the rupture of alveoli, and inhaled air can be leaked into the blood vessels. Other more-common causes include the puncture of the subclavian vein
by accident or during operation where there is negative pressure. Air is then sucked into the veins by the negative pressure caused by thoracic expansion during the inhalation phase of respiration. Air embolism can also happen during intravenous therapy, when air is leaked into the system (however this iatrogenic error in modern medicine is extremely rare).
Gas embolism is a common concern for deep-sea divers because the gases in our blood (usually nitrogen and helium) can be easily dissolved at higher amounts during the descent into deep sea. However, when the diver ascends to the normal atmospheric pressure, the gases become insoluble, causing the formation of small bubbles in the blood. This is also known as decompression sickness
or the Bends. This phenomenon is explained by Henry's Law
in physical chemistry
.
Embolism by other materials are rather rare. Septic embolism happens when a purulent tissue (pus
-containing tissue) is dislodged from its original focus. Tissue embolism is a near-equivalent to cancer
metastasis
, which happens when cancer tissue infiltrates blood vessels, and small fragments of them are released into the blood stream. Foreign-body embolism happens when exogenous—and only exogenous—materials such as talc
enter the blood stream and cause occlusion or obstruction of blood circulation. Amniotic-fluid embolism is a rare complication of childbirth
.
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...
, which is capable of clogging arterial capillary beds (create an arterial occlusion
Vascular occlusion
Vascular occlusion is a sudden blockage of a blood vessel, usually with a clot. It differs from thrombosis in that it can be used to describe any form of blockage, not just one formed by a clot. When it occurs in a major vein, it can, in some cases, cause deep vein thrombosis. The condition is...
) at a site distant from its point of origin.
By contrast there are non-traveling blockages that develop locally from vascular trauma or epithelial pathology and vascular inflammation
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
— like atheroma
Atheroma
In pathology, an atheroma is an accumulation and swelling in artery walls that is made up of macrophage cells, or debris, that contain lipids , calcium and a variable amount of fibrous connective tissue...
, thrombi
Thrombus
A thrombus , or blood clot, is the final product of the blood coagulation step in hemostasis. It is achieved via the aggregation of platelets that form a platelet plug, and the activation of the humoral coagulation system...
. However, if a thrombus breaks loose from its genesis site it becomes a thrombo-embolus and if not broken down during transit, may cause embolism
Embolism
In medicine, an embolism is the event of lodging of an embolus into a narrow capillary vessel of an arterial bed which causes a blockage in a distant part of the body.Embolization is...
(s).
The term was coined in 1848 by Rudolf Virchow
Rudolf Virchow
Rudolph Carl Virchow was a German doctor, anthropologist, pathologist, prehistorian, biologist and politician, known for his advancement of public health...
.
Classification by the Material of Composition
- Thromboembolism – embolism of thrombus (blood clot).
- Cholesterol embolismCholesterol embolismCholesterol embolism occurs when cholesterol is released, usually from an atherosclerotic plaque, and travels along with the bloodsteam to other places in the body, where it obstructs blood vessels...
– embolism of cholesterol, often from atherosclerotic plaque inside a vessel. - Fat embolismFat embolismA fat embolism is a type of embolism that is often caused by physical trauma such as fracture of long bones, soft tissue trauma and burns.-Presentation:...
– embolism of bone fracture or fat droplets. - Air embolismAir embolismAn air embolism, or more generally gas embolism, is a pathological condition caused by gas bubbles in a vascular system. The most common context is a human body, in which case it refers to gas bubbles in the bloodstream...
(also known as a gas embolism) – embolism of air bubbles. - Septic embolismSeptic embolismA septic embolism is a type of embolism that is infected with bacteria, resulting in the formation of pus. These may become dangerous if dislodged from their original location. Like other emboli, a septic embolism may be fatal....
– embolism of pus-containing bacteria. - Tissue embolism – embolism of small fragments of tissue.
- Foreign body embolism – embolism of foreign materials such as talc and other small objects.
- Amniotic fluid embolismAmniotic fluid embolismAmniotic fluid embolism is a rare and incompletely understood obstetric emergency in which amniotic fluid, fetal cells, hair, or other debris enters the mother's blood stream via the placental bed of the uterus and triggers an allergic reaction. This reaction then results in cardiorespiratory ...
– embolism of amniotic fluid, foetal cells, hair, or other debris that enters the mother's bloodstream via the placental bed of the uterus and triggers an allergic reaction.
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. Note that the free-moving thrombus is called an embolus. 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
Stasis (medicine)
In medicine, stasis is the state in which the normal flow of a body liquid stops, for example the flow of blood through vessels or of intestinal contents through the digestive tract....
and ischemia
Ischemia
In medicine, ischemia is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue. It may also be spelled ischaemia or ischæmia...
. 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.
Fat embolism
Fat embolism
A fat embolism is a type of embolism that is often caused by physical trauma such as fracture of long bones, soft tissue trauma and burns.-Presentation:...
usually occurs when endogenous (from sources within the organism) fat tissue escapes into the blood circulation. The usual cause of fat embolism is therefore the fracture
Fracture
A fracture is the separation of an object or material into two, or more, pieces under the action of stress.The word fracture is often applied to bones of living creatures , or to crystals or crystalline materials, such as gemstones or metal...
of tubular bones (such as the femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
), which will lead to the leakage of fat tissue within the bone marrow into ruptured vessels. There are also exogenous (from sources of external origin) causes such as intravenous injection of emulsions.
An air embolism
Air embolism
An air embolism, or more generally gas embolism, is a pathological condition caused by gas bubbles in a vascular system. The most common context is a human body, in which case it refers to gas bubbles in the bloodstream...
, on the other hand, is usually always caused by exogenic factors. This can be the rupture of alveoli, and inhaled air can be leaked into the blood vessels. Other more-common causes include the puncture of the subclavian vein
Subclavian vein
The subclavian veins are two large veins, one on either side of the body. Their diameter is approximately that of the smallest finger.-Path:Each subclavian vein is a continuation of the axillary vein and runs from the outer border of the first rib to the medial border of anterior scalene muscle...
by accident or during operation where there is negative pressure. Air is then sucked into the veins by the negative pressure caused by thoracic expansion during the inhalation phase of respiration. Air embolism can also happen during intravenous therapy, when air is leaked into the system (however this iatrogenic error in modern medicine is extremely rare).
Gas embolism is a common concern for deep-sea divers because the gases in our blood (usually nitrogen and helium) can be easily dissolved at higher amounts during the descent into deep sea. However, when the diver ascends to the normal atmospheric pressure, the gases become insoluble, causing the formation of small bubbles in the blood. This is also known as decompression sickness
Decompression sickness
Decompression sickness describes a condition arising from dissolved gases coming out of solution into bubbles inside the body on depressurization...
or the Bends. This phenomenon is explained by Henry's Law
Henry's law
In physics, Henry's law is one of the gas laws formulated by William Henry in 1803. It states that:An equivalent way of stating the law is that the solubility of a gas in a liquid at a particular temperature is proportional to the pressure of that gas above the liquid...
in physical chemistry
Physical chemistry
Physical chemistry is the study of macroscopic, atomic, subatomic, and particulate phenomena in chemical systems in terms of physical laws and concepts...
.
Embolism by other materials are rather rare. Septic embolism happens when a purulent tissue (pus
Pus
Pus is a viscous exudate, typically whitish-yellow, yellow, or yellow-brown, formed at the site of inflammatory during infection. An accumulation of pus in an enclosed tissue space is known as an abscess, whereas a visible collection of pus within or beneath the epidermis is known as a pustule or...
-containing tissue) is dislodged from its original focus. Tissue embolism is a near-equivalent to cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
metastasis
Metastasis
Metastasis, or metastatic disease , is the spread of a disease from one organ or part to another non-adjacent organ or part. It was previously thought that only malignant tumor cells and infections have the capacity to metastasize; however, this is being reconsidered due to new research...
, which happens when cancer tissue infiltrates blood vessels, and small fragments of them are released into the blood stream. Foreign-body embolism happens when exogenous—and only exogenous—materials such as talc
Talc
Talc is a mineral composed of hydrated magnesium silicate with the chemical formula H2Mg34 or Mg3Si4O102. In loose form, it is the widely-used substance known as talcum powder. It occurs as foliated to fibrous masses, its crystals being so rare as to be almost unknown...
enter the blood stream and cause occlusion or obstruction of blood circulation. Amniotic-fluid embolism is a rare complication of childbirth
Childbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...
.