Thrombosis is the formation of a thrombus inside a blood vessel, obstructing the flow of blood through the circulatory system
A thrombus is a structureless mass of red blood cells, platelets, leukocytes and fibrin.
Thrombosis results from an imbalance between antithrombotic and prothrombotic activities in which prothrombotic activities predominate.
Classically, thrombosis is caused by abnormalities in one or more of the following (Virchow’s triad):
White thrombus:
Red thrombus:
Arterial thrombosis corresponds to blockage of an artery by a thrombus, usually following rupture of an atherosclerotic plaque and leads to infarction (i.e. necrosis) of the tissues supplied by the artery.
Venous thrombosis corresponds to formation of a thrombus in a vein. There are two types of venous thrombosis:
Embolisation occurs when part of the thrombus breaks off and is transported by the blood flow further downstream to other tissues where it can lodge and block the blood supply, leading to tissue damage.
A transported thrombus fragment is called an embolus. Transport of an embolus into the lungs, via the right side of the heart, results in pulmonary embolism, potentially leading to the infarction (i.e. necrosis) of lung tissues. Embolisation is most typically the consequence of deepvein thrombosis.
Venous thrombi mostly form in regions of slow or disturbed blood flow, typically the large sinuses and valve cusp pockets in the deep veins of the calf.
Activation of coagulation, thrombin generation and fibrin formation
Proximal progression along the vein
