Classification & external resources

ICD-10	I80.-I82.
ICD-9	437.6, 453, 671.5, 671.9
MeSH	D013927

Thrombosis is the formation of a clot or thrombus inside a blood vessel, obstructing the flow of blood through the circulatory system. Thromboembolism is a general term describing both thrombosis and its main complication which is embolisation. The term was coined in 1848 by Rudolph Carl Virchow.^[1]

Causes

Classically, thrombosis is caused by abnormalities in one or more of the following (Virchow's triad):

• The composition of the blood (hypercoagulability)
• Quality of the vessel wall (endothelial cell injury)
• Nature of the blood flow (hemostasis)
• Slow nerve action can contribute (check this fact?)

The formation of a thrombus is usually caused by the top three causes, known as Virchow's triad. To elaborate, the pathogenesis includes: an injury to the vessel's wall (such as by trauma, infection, or turbulent flow at bifurcations); by the slowing or stagnation of blood flow past the point of injury (which may occur after long periods of sendentary behavior - for example, sitting on a long airplane flight; by a blood state of hypercoagulability (caused for example, by genetic deficiencies or autoimmune disorders).

High altitude has also been known to induce thrombosis [1][2]. Occasionally, abnormalities in coagulation are to blame. Intravascular coagulation follows, forming a structureless mass of red blood cells, leukocytes, and fibrin.

Classification

There are two distinct forms of thrombosis:

Venous thrombosis

Main article: Venous thrombosis

• Deep venous thrombosis (with or without pulmonary embolism; together classified as venous thromboembolism/VTE)
• Portal vein thrombosis
• Renal vein thrombosis
• hepatic vein thrombosis (Budd-Chiari syndrome)
• Paget-Schroetter disease (upper extremity vein)
• Thoracic outlet syndrome (the cause of most Subclavian Vein Thrombosis unrelated to trauma)

Arterial thrombosis

• Stroke (either thrombotic or embolic)
• Myocardial infarction (usually coronary thrombosis due to rupture of an atherosclerotic plaque)
• Thoracic outlet syndrome (may precipitate arterial thrombosis as well as venous)

Embolisation

If a bacterial infection is present at the site of thrombosis, the thrombus may break down, spreading particles of infected material throughout the circulatory system (pyemia, septic embolus) and setting up metastatic abscesses wherever they come to rest. Without an infection, the thrombus may become detached and enter circulation as an embolus, finally lodging in and completely obstructing a blood vessel (an infarction). The effects of an infarction depend on where it occurs.

Most thrombi, however, become organized into fibrous tissue, and the thrombosed vessel is gradually recanalized.

See also

• Anticoagulants

References

•  • [ e] Circulatory system pathology (, )
Hypertension	Hypertensive heart disease - Hypertensive nephropathy - Secondary hypertension (Renovascular hypertension)
Ischaemic heart disease	Angina pectoris - Prinzmetal's angina - Myocardial infarction - Dressler's syndrome
Pulmonary circulation	Pulmonary embolism - Cor pulmonale
Pericardium	Pericarditis - Pericardial effusion - Cardiac tamponade
Endocardium/heart valves	Endocarditis - Mitral regurgitation - Mitral valve prolapse - Mitral stenosis - Aortic valve stenosis - Aortic insufficiency - Pulmonary valve stenosis
Myocardium	Myocarditis - Cardiomyopathy (Dilated cardiomyopathy, Hypertrophic cardiomyopathy, Loeffler endocarditis, Restrictive cardiomyopathy) - Arrhythmogenic right ventricular dysplasia
Electrical conduction system of the heart	Heart block: AV block (First degree, Second degree, Third degree) - Bundle branch block (Left, Right) - Bifascicular block - Trifascicular block Pre-excitation syndrome (Wolff-Parkinson-White, Lown-Ganong-Levine) - Long QT syndrome - Adams-Stokes syndrome - Cardiac arrest Arrhythmia: Paroxysmal tachycardia (Supraventricular, AV nodal reentrant, Ventricular) - Atrial flutter - Atrial fibrillation - Ventricular fibrillation - Premature contraction (Atrial, Ventricular) - Sick sinus syndrome
Other heart conditions	Heart failure - Cardiomegaly - Ventricular hypertrophy (Left, Right)
Cerebrovascular diseases	Intracranial hemorrhage/cerebral hemorrhage: Extra-axial hemorrhage (Epidural hemorrhage, Subdural hemorrhage, Subarachnoid hemorrhage) - Intra-axial hematoma (Intraventricular hemorrhages, Intraparenchymal hemorrhage) - Anterior spinal artery syndrome - Binswanger's disease - Moyamoya disease
Arteries, arterioles and capillaries	Atherosclerosis (Renal artery stenosis) - Aortic dissection/Aortic aneurysm (Abdominal aortic aneurysm) - Aneurysm - Raynaud's phenomenon/Raynaud's disease - Buerger's disease - Arteritis (Aortitis) - Intermittent claudication - Arteriovenous fistula - Hereditary hemorrhagic telangiectasia - Spider angioma
Veins, lymphatic vessels and lymph nodes	Thrombosis/Phlebitis/Thrombophlebitis (Deep vein thrombosis, May-Thurner syndrome, Portal vein thrombosis, Venous thrombosis, Budd-Chiari syndrome, Renal vein thrombosis, Paget-Schroetter disease) - Varicose veins (Hemorrhoid, Esophageal varices, Varicocele, Gastric varices, Caput medusae) - Superior vena cava syndrome - Lymph(Lymphadenitis, Lymphedema, Lymphangitis)
See also (, )