Glossary

A-Z of important terminology in VTE

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

Abnormal coagulation
Can lead to either excessive bleeding or excessive clotting, both of which can be dangerous, causing heart attack, stroke, or pulmonary embolism (PE).
 
Aggregation
Stage of clot formation when platelets clump together.
 
Anticoagulants
Anticoagulants are blood-thinning medications that inhibit some of the blood clotting factors, therefore increasing the time it takes for a blood clot to form and lessening the risk of VTE.
 
Antiplatelet agents
Drugs that partially inhibit platelet aggregation, helping to stop clots from forming (mainly used for prevention of arterial blood clots, e.g. aspirin or clopidogrel).
 
Antithrombin III
A naturally occurring protein that is an important inhibitor of blood clot formation; also called ATIII.
 
Arterial embolism
Sudden blockage of an artery by a blood clot which the blood has carried from another location.
 
Atherosclerosis
A primary cause of cardiovascular disease (CVD), atherosclerosis is a localized hardening and narrowing of the arteries caused by the slow, progressive build-up of plaque under the arterial wall lining. It may chronically restrict blood flow and oxygenation to the target organ and be acutely complicated by a clot if the plaque disrupts (see thrombus, atherothrombosis).
 
Atherothrombosis
This is characterized by sudden, unpredictable, atherosclerotic plaque disruption, leading to an abrupt platelet activation and clot formation. It can partially or totally block arterial blood flow in the artery and cause an abrupt local decrease in oxygen supply to the target organ. Depending on the artery, atherothrombosis can result in serious damages to the organ involved, such as: heart muscle lesions (myocardial infarction), brain lesions, and stroke.  

B

Blood clot
A clot that forms in a blood vessel is called a thrombus. A blood clot is a mass of red blood cells, platelets (small blood cells) clumped together, and a protein called fibrin.

C

Chronic venous insufficiency
A condition in which deep veins within the limbs do not drain the flow of blood adequately over a long period of time. See post-thrombotic syndrome (PTS).
 
Clotting
The process by which fluid blood changes to a solid.
 
Coagulation
Blood clotting; formation of a blood clot.
 
Coagulation cascade
A series of cellular and molecular reactions among blood clotting factors that cause clotting. The cascade is a process occurring when a blood vessel is injured or blood flow is disrupted; the end result is a blood clot (fibrin mesh).
 
Clotting factors
A group of chemicals in the blood (factors I to XIII) that interact to make blood clots.
 
Complications of pulmonary embolism
Significant shortness of breath, marked exercise limitation, and even death. Patients may develop pulmonary hypertension as respiratory failure develops. If untreated, this can impair the transport of oxygen to the blood and stresses the heart, causing heart failure.
 
Coronary artery disease (CAD)
Disease characterized by atherosclerosis of the coronary arteries; may cause angina pectoris and myocardial infarction. 

D

Deep veins
Unlike the superficial veins just below the skin surface, most of the deep veins are surrounded by powerful muscles that contract to force blood back to the heart. One-way valves inside the veins prevent backflow of blood between muscle contractions. When the rhythm of circulation slows down due to illness, injury, or inactivity, there may be a tendency for blood to accumulate or ‘pool’. A static pool of blood provides an ideal environment for clot formation.
 
Deep-vein thrombosis (DVT)
The formation of a blood clot (thrombus) in any deep veins of the body (leg veins, pelvis or major upper-extremity veins). In 60% of cases, DVT develops in the lower limbs and as it is potentially life-threatening rapid assessment and treatment are essential.
 
D-dimer blood test
A fibrin degradation product that is released into the circulation during a DVT/PE episode. PE is extremely unlikely if results are normal.
 
Duplex colour scanner
Displays real-time moving structures, usually blood, by superimposing colour onto the grey-scale ultrasonic images and detects the moving blood by using the Doppler effect. See ultrasonic imaging of blood vessels (ultrasound).

E

Embolism
Sudden blockage of an artery by a clot or foreign material carried and deposited by the blood current.

F

Fibrin
A protein necessary for blood clotting; fibrin forms a web-like mesh that traps platelets and red blood cells and holds a clot together.

H

Heart failure (HF)
Disease state arising from impaired pumping of the heart, causing blood to back-up and accumulate in the blood vessels or lungs.
 
Haemostasis
The stopping of bleeding through natural (clot formation, constriction of blood vessels), artificial (compression, ligation), or surgical means.
 
Heparin
An anticoagulant commonly used to prevent the formation of blood clots (thrombosis).

I

Infarction
Cell death due to insufficient supply of oxygen.
 
Ischaemic heart disease
Disturbance of heart function resulting from inadequate supply of oxygen to the heart muscle; also called coronary artery disease (CAD).

L

Low-molecular-weight heparin (LMWH)
An anticoagulant medication used to prevent the formation of new blood clots and treat DVT. Its molecule is one-third the size of standard heparin; potential advantages include convenient once-a-day dosing, more predictable anticoagulant response.

M

Myocardial infarction (MI)
Abrupt blockage of blood flow into the coronary arteries, resulting in insufficient supply of oxygen (ischaemia) to the heart and death of the affected heart cells; also called heart attack.

P

Plaque
The build-up of cholesterol, calcium, and fatty material within an artery wall occurring in atherosclerotic disease. Also called ‘atherosclerotic plaque’, it can be hard and cause the artery walls to thicken and harden, or it can be soft and unstable (easily disrupted).
 
Post-thrombotic syndrome (PTS)
Occurring as a delayed consequence of previous venous damage and circulation disruption by DVT, PTS is characterized by recurrent or continuous leg swelling, leg pain (heaviness or aching), reddish-brown skin changes and coarsening skin texture. Patients may also develop irregular hollow ulceration around the ankle. See also chronic venous insufficiency. Approximately 30% of patients with DVT have an added risk of developing post-thrombotic syndrome (PTS).
 
Pulmonary embolism (PE)
The development of a PE is the major risk associated with VTE. Without treatment, up to 25% of all leg DVTs will have a piece of clot detach (an embolus), travel through blood circulation, and lodge in the lumen (open cavity) of a pulmonary artery, which may be life threatening. Symptoms include sudden shortness of breath, chest pain or discomfort (worse with breathing or coughing), a general sense of nervousness or anxiety, and rapid heart and respiratory rates.
 
Prophylaxis
Measures to preserve health and prevent a disease; also means protective treatment for disease. VTE prophylaxis may include lifestyle changes, mechanical measures with support stockings, and pharmacological options with anticoagulants or a combination of all.

S

Stasis
The slowing of blood flow.
 
Stenosis
Narrowing of the inside of a blood vessel.
 
Stockings
Graduated compression stockings achieve a pressure gradient and mimic the deep-leg-vein calf muscle pumps to promote efficient emptying of vein circuits and valvular systems.

Stroke
Tissue death within the central nervous system resulting from a clot blocking a blood vessel in the brain, or haemorrhaging caused by a ruptured blood vessel on the surface or within the brain.
 
Subcutaneous
Given or occurring under the skin.
 
Superficial veins
Veins lying close to the surface of the skin.

T

Thrombolytic agents
Medicines used to dissolve blood clots formed in certain blood vessels (thrombolysis).
 
Thromboprophylaxis
The use of drugs or other protective therapies to prevent clotting risk (thrombosis).
 
Thrombosis
The formation, presence or development of a thrombus (a clot of coagulated blood attached at the site of its formation) within the lumen (open cavity) of a blood vessel or chambers of the heart. Thrombosis can occur in an artery (arterial thrombosis) or in a body’s vein (venous thrombosis).
 
Thrombus
Blood clot formed from red blood cells, platelets and a protein called fibrin inside a blood vessel or cavity of the heart; may obstruct a blood vessel at its point of formation or travel to other areas of the body. Plural: thrombi.
 
Tissue factor
A protein released from damaged tissue that triggers the clotting cascade.

U

Ultrasonic imaging of blood vessels (ultrasound)
Ultrasonic scanning is established as a valuable non-invasive, painless, cost-effective method for exploring lower limb vascular disease and investigation of DVT.

Unstable angina
A form of angina pectoris (chest pain) characterized by sudden changes in the severity or length of attacks.

V

W