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A thrombus (Greek ???µß??), or blood clot, is the final product of the blood coagulation step in hemostasis
Hemostasis

Hemostasis is a complex process which causes the bleeding process to stop. Most time this includes the changing of blood from a fluid to a solid state....
. It is achieved via the aggregation of platelets that form a platelet plug, and the activation of the humoral coagulation
Coagulation

Coagulation is a complex process by which blood forms clots. It is an important part of hemostasis , wherein a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop hemorrhage and begin repair of the damaged vessel....
 system (i.e. clotting factors). A thrombus is normal in cases of injury
Injury

Injury or bodily injury is damage or harm caused to the structure or Purpose of the body caused by an outside wiktionary:agent or force, which may be physical or chemical....
, but pathologic
Pathology

Pathology is the study and diagnosis of disease through examination of Organ , tissue , bodily fluids and whole bodies . The term also encompasses the related science study of disease processes, called General pathology....
 in instances of thrombosis
Thrombosis

Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot, because the first step in repairing it is to prevent loss of blood....
.

Specifically, a thrombus is a blood clot in an intact blood vessel. A thrombus in a large blood vessel will decrease blood flow through that vessel.






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Encyclopedia


A thrombus (Greek ???µß??), or blood clot, is the final product of the blood coagulation step in hemostasis
Hemostasis

Hemostasis is a complex process which causes the bleeding process to stop. Most time this includes the changing of blood from a fluid to a solid state....
. It is achieved via the aggregation of platelets that form a platelet plug, and the activation of the humoral coagulation
Coagulation

Coagulation is a complex process by which blood forms clots. It is an important part of hemostasis , wherein a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop hemorrhage and begin repair of the damaged vessel....
 system (i.e. clotting factors). A thrombus is normal in cases of injury
Injury

Injury or bodily injury is damage or harm caused to the structure or Purpose of the body caused by an outside wiktionary:agent or force, which may be physical or chemical....
, but pathologic
Pathology

Pathology is the study and diagnosis of disease through examination of Organ , tissue , bodily fluids and whole bodies . The term also encompasses the related science study of disease processes, called General pathology....
 in instances of thrombosis
Thrombosis

Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot, because the first step in repairing it is to prevent loss of blood....
.

Specifically, a thrombus is a blood clot in an intact blood vessel. A thrombus in a large blood vessel will decrease blood flow through that vessel. In a small blood vessel, blood flow may be completely cut-off resulting in death of tissue supplied by that vessel. If a thrombus dislodges and becomes free-floating, it is an embolus
Embolism

In medicine, an embolism occurs when an object migrates from one part of the body and causes a blockage of a blood vessel in another part of the body....
.

Some of the conditions which elevate risk of blood clots developing include atrial fibrillation
Atrial fibrillation

Atrial fibrillation is a cardiac arrhythmia that involves the two upper chambers of the heart. It can often be identified by taking a pulse and observing that the heartbeats don't occur at regular intervals, but a conclusive indication of AF is the absence of P waves on an electrocardiogram ....
 (a form of cardiac arrhythmia
Cardiac arrhythmia

Cardiac arrhythmia is a term for any of a large and heterogeneous group of conditions in which there is abnormal Electrical conduction system of the heart in the heart....
), heart valve replacement, a recent heart attack
Myocardial infarction

Myocardial infarction , commonly known as a heart attack, occurs when the Blood flow to part of the heart is interrupted. This is most commonly due to occlusion of a coronary artery following the rupture of a Vulnerable plaque, which is an unstable collection of lipids and white blood cells in the wall of an artery....
, extended periods of inactivity (see deep venous thrombosis), and genetic or disease-related deficiencies in the blood's clotting abilities.

Blood clot prevention reduces the risk of stroke, heart attack and pulmonary embolism
Pulmonary embolism

Pulmonary embolism is a blockage of the pulmonary artery or one of its branches, usually occurring when a deep vein thrombosis becomes dislodged from its site of formation and travels, or embolism, to the pulmonary artery blood supply of one of the lungs....
. Heparin
Heparin

Heparin, a highly-sulfated glycosaminoglycan, is widely used as an injectable anticoagulant and has the highest negative charge density of any known biomolecule....
 and warfarin
Warfarin

Warfarin is an anticoagulant. It was initially marketed as a pesticide against rats and mice, and is still popular for this purpose, although more potent poisons such as brodifacoum have since been developed....
 are often used to inhibit the formation and growth of existing blood clots; they are able to decrease blood coagulation by inhibiting vitamin K epoxide reductase, an enzyme that recycles oxidated vitamin K to its reduced form after it has participated in the carboxylation of several blood coagulation proteins, mainly prothrombin and factor VII.

Virchow's triad
Virchow's triad

Virchow's triad encompasses the three broad categories of factors that are thought to contribute to thrombosis.It is named for Germany physician Rudolf Virchow ....
 describes the conditions necessary for thrombus formation:

  1. Changes in vessel wall morphology (e.g. trauma, atheroma
    Atheroma

    In pathology, an atheroma is an accumulation and swelling in artery walls that is made up of cells , or cell debris, that contain lipids , calcium and a variable amount of fibrous connective tissue....
    )
  2. Changes in blood flow through the vessel (e.g. valvulitis
    Valvulitis

    Excess long comment to prevent listing on...
    , aneurysm
    Aneurysm

    An aneurysm is a localized, blood-filled dilation of a blood vessel caused by disease or weakening of the vessel wall.Aneurysms most commonly occur in artery at the base of the brain and in the aorta ....
    )
  3. Changes in blood composition (e.g. leukaemia, hypercoagulability disorders)


Disseminated intravascular coagulation
Disseminated intravascular coagulation

Disseminated intravascular coagulation , also known as consumptive coagulopathy, is a pathological activation of coagulation mechanisms that happens in response to a variety of diseases....
 (DIC) involves widespread microthrombi formation throughout the majority of the blood vessels. This is due to excessive consumption of coagulation factors and fibrinolysis
Fibrinolysis

Fibrinolysis is the process wherein a fibrin thrombus, the product of coagulation, is broken down. Its main enzyme plasmin cuts the fibrin mesh at various places, leading to the production of circulating fragments that are cleared by other proteases or by the kidney and liver....
 using all of the body's available platelets and clotting factors. The end result is ischaemic necrosis of the affected tissue/organs and spontaneous bleeding due to the lack of clotting factors. Causes are septicaemia, acute leukaemia, shock, snake bites or severe trauma. Treatment involves the use of fresh, frozen plasma to restore the level of clotting factors in the blood.

See also

  • Embolism
    Embolism

    In medicine, an embolism occurs when an object migrates from one part of the body and causes a blockage of a blood vessel in another part of the body....
  • Thrombolysis
    Thrombolysis

    Thrombolysis is the breakdown of thrombosis by pharmacology means. It is colloquially referred to as clot busting for this reason. It works by stimulating fibrinolysis by plasmin through infusion of analogs of tissue plasminogen activator, the protein that normally activates plasmin....
     ("Destruction of clot")
  • Thrombogenicity
    Thrombogenicity

    Thrombogenicity refers to the tendency of a material in contact with the blood to produce a thrombus, or clot. It not only refers to fixed thrombi but also to emboli, thrombi which have become detached and travel through the bloodstream....
     (the tendency to clot)
  • National Alliance for Thrombosis and Thrombophilia
    National Alliance for Thrombosis and Thrombophilia

    The National Alliance for Thrombosis and Thrombophilia is a nationwide not for profit alliance of patients and medical professionals committed to raising awareness about thrombosis and thrombophilia and is dedicated to preventing and treating health problems caused by blood clots and blood clotting disorders....


External links

  • -- , Medical Information Resource, 1999
  • - NATF is a nonprofit organization dedicated to promoting thrombosis research, prevention and education, public policy, and advocacy outreach.
  • .
  • - has extensive stories from patients and family members on living with Thrombosis and Thrombophilia, assembled frequently asked questions and created publications addressing specific blood clot issues.