Acute coronary syndrome
A range of acute myocardial ischaemic states encompassing unstable angina, non-ST-elevation myocardial infarction and ST-elevation myocardial infarction.
Autoimmune antibodies including anticardiolipin antibodies and lupus anticoagulant, produced against phospholipid in cell membranes. The production of these antibodies may lead to formation of blood clots, pregnancy loss or pregnancy-related complications, and is known as antiphospholipid syndrome (APS).
An oral, direct Factor Xa inhibitor (Eliquis®) that has received regulatory approval for venous thromboembolism prevention in patients undergoing hip or knee replacement surgery, the treatment and secondary prevention of deep vein thrombosis and pulmonary embolism, and the prevention of stroke and systemic embolism in adult patients with non-valvular atrial fibrillation.
Abnormal heart rhythm as opposed to normal sinus rhythm. In arrhythmia, electrical impulses that coordinate heart rhythm are disturbed, causing the heart to beat too fast, too slow or irregularly.
A condition in which the arterial wall thickens as a result of the accumulation of fatty deposits including cholesterol. It is a chronic inflammatory response in the arterial walls, promoted by low-density lipoproteins and caused largely by the accumulation of white blood cells, macrophages and vascular smooth muscle cells.
A thickening of the arterial wall, which may consist of cholesterol, calcium, cellular debris and vascular smooth muscle cells. The plaque may grow and lead to narrowing of the artery, causing serious problems, including heart attack, stroke or even death.
The most common type of cardiac arrhythmia (irregular heartbeat) associated with an increased risk of stroke, congestive heart failure and mortality.
A biomarker (biological marker) is an indicator of a biological state that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes or pharmacological responses to a therapeutic intervention. Examples of biomarkers associated with VTE include D-dimer and soluble P-selectin.
A parenteral reversible direct inhibitor of thrombin that inhibits both circulating and clot-bound thrombin, while also inhibiting thrombin-mediated platelet activation and aggregation.
A complex of three myocardial regulatory proteins – troponin I, C and T, which are found in varying amounts in skeletal and cardiac muscle. Together, these regulate the calcium-modulated interaction of actin and myosin. Troponin levels are sensitive markers of myocardial injury and various other heart disorders.
Cardioembolic stroke is caused by blood clots that originate in the heart and is the most severe form of ischaemic stroke, which accounts for a substantial proportion of all cerebral infarctions.
A physiological state in which inadequate tissue perfusion results in cardiac dysfunction, most often systolic.
The interdependence of the heart, lungs and oxygen-carrying capacity of any given patient.
A method of re-establishing normal sinus rhythm in patients with non-valvular atrial fibrillation that can be either electrical or pharmacological.
Commonly used technique to correct cardiac arrhythmias, including atrial fibrillation. Cardiac tissue causing the arrhythmia is destroyed and normal sinus rhythm is often restored.
A group of diseases of the blood vessels supplying the brain, frequently caused by hypertension. Such diseases can include stroke, haemorrhagic stroke, ischaemia or other blood vessel dysfunctions.
An index to determine the risk of stroke in patients with atrial fibrillation. One point each is assigned for the presence of: Congestive heart failure, Hypertension, Age ≥75 years and Diabetes mellitus; and two points for a history of Stroke or transient ischaemic attack.
A risk factor-based approach defining ‘major’ and ‘clinically relevant non-major’ risk factors for stroke in patients with atrial fibrillation. The CHA2DS2-VASc scheme assigns points for each of the following factors: Congestive heart failure/left ventricular dysfunction (1 point), Hypertension (1 point), Age ≥75 years [doubled] (2 points), Diabetes (1 point), Stroke [doubled] (2 points) – Vascular disease (1 point), Age 65–74 years (1 point), and Sex category [female] (1 point).
Chronic thromboembolic pulmonary hypertension
A long-term complication that can arise from a pulmonary embolism and manifests as non-specific symptoms mainly caused by right heart failure (such as dyspnoea on exertion, fatigue and syncope).
Also known as CAT scan. A radiographic technique that uses a computer to assimilate multiple X-ray images into a two-dimensional cross-sectional image. Types of computed tomography include:
Helical/spiral CT – a computed tomography technology involving movement in a helical pattern for the purpose of increasing resolution. Most modern hospitals use spiral CT scanners.
CT pulmonary angiography – highly sensitive and specific diagnostic test, involving injection of intravenous contrast medium to visualize the pulmonary arteries.
CT venography – contrast-enhanced axial CT images. Also known as ‘indirect CT venography’, it is performed in conjunction with CT pulmonary angiography and not as a standalone examination.
Coronary artery disease
Coronary artery disease is the narrowing or blockage of the coronary arteries, usually caused by atherosclerosis.
Coronary artery bypass graft (CABG) or coronary artery bypass surgery
A surgical procedure used to treat coronary heart disease, which involves taking a blood vessel from another part of the body, usually the chest or leg, and attaching it to the coronary artery above and below the narrowed area or blockage. This new blood vessel (graft) diverts the flow of blood around the part of the coronary artery that is narrowed or blocked.
Restoration of blood supply to ischaemic heart tissue, using methods such as chemical dissolution of an occluding thrombus, administration of vasodilator drugs, angioplasty, catheterization or artery bypass graft surgery.
Restoration of blood supply to the heart, commonly performed using percutaneous coronary intervention or coronary artery bypass grafting procedures.
A family of diverse cell-signalling proteins secreted by many cells, which are used extensively in intercellular communication. Cytokines can be classified as proteins, peptides or glycoproteins.
An oral direct thrombin inhibitor (Pradaxa®) that has received regulatory approval for venous thromboembolism prevention in patients undergoing hip or knee replacement surgery, the treatment and secondary prevention of deep vein thrombosis and pulmonary embolism (after treatment with a parenteral anticoagulant for ≥5 days), and the prevention of stroke and systemic embolism in adult patients with non-valvular atrial fibrillation.
A marker of endogenous fibrinolysis that can be routinely used as a diagnostic aid to exclude deep vein thrombosis or pulmonary embolism.
Deep vein thrombosis
A thrombus in a deep vein, usually in the leg.
A disease of the insulin-producing beta cells of the pancreas that affects the body’s ability to regulate blood sugar levels. There are two types of diabetes mellitus: in type 1 diabetes, the beta cells are damaged so that little or no insulin is produced; in type 2 diabetes, the pancreas does not produce enough insulin or the insulin does not work properly.
Direct Factor Xa inhibitors
A class of anticoagulant drugs that act directly on activated Factor X (Factor Xa) in the coagulation cascade and do not require antithrombin as a mediator. Examples include apixaban, rivaroxaban, betrixaban and edoxaban.
Direct thrombin inhibitors
A class of anticoagulant drugs that act directly on thrombin in the coagulation cascade. Examples include hirudin, bivalirudin, argatroban, melagatran and dabigatran.
Dual antiplatelet therapy
Treatment with two antiplatelet agents concurrently.
An abnormal concentration of lipids or lipoproteins in the blood.
Difficult or laboured breathing; shortness of breath.
The process of using an echocardiogram to record depolarization and repolarization voltages of the cardiac muscle, via detection of electrical activity by electrodes applied to the skin. Used to detect abnormal heart rhythms or cardiac muscle damage.
An oral, direct Factor Xa inhibitor (Savaysa®) that has been approved in Japan for the prevention of venous thromboembolism in patients undergoing major orthopaedic surgery, and in Japan and the US for the treatment and secondary prevention of deep vein thrombosis and pulmonary embolism (after treatment with a parenteral anticoagulant for 5–10 days), and the prevention of stroke in adult patients with non-valvular atrial fibrillation.
Any detached, travelling intravascular mass carried by the circulation, which is capable of blocking arterial capillary beds at a site distant from its point of origin. If a thrombus breaks loose from its original site, it becomes a thromboembolus; if it is not broken down during transit, may cause an embolism in another artery or vein.
A procedure that involves unblocking venous segments that are narrowed by intraluminal scars and masses to improve circulation.
A low molecular weight heparin (Clexane®, Lovenox®) approved for the prevention and treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE) of venous origin, in particular those that may be associated with orthopaedic or general surgery; the prevention of DVT and PE in medical patients bedridden owing to acute illness; the acute treatment of unstable angina and non-ST-elevation myocardial infarction (administered concurrently with acetylsalicylic acid) and ST-elevation myocardial infarction; and the prevention of thrombus formation in the extracorporeal circulation during haemodialysis.
Factor V Leiden
A variant of human Factor V, associated with hypercoagulability disorder, which is relatively common in some populations. Carriers of Factor V Leiden have a modest risk of developing VTE.
A process whereby thrombi are broken down by the enzyme plasmin. Primary fibrinolysis is a normal process of the body; whereas secondary fibrinolysis is the breakdown of clots due to a medicine, a medical disorder or some other cause.
A synthetic Factor Xa inhibitor (Arixtra®) approved for the prevention of deep vein thrombosis (DVT) and pulmonary embolism (PE) in adult patients undergoing major orthopaedic surgery, adult patients undergoing abdominal surgery who are at high risk of thromboembolic complications, the prevention of DVT and PE in adult medical patients who are at high risk of pulmonary embolism (PE) and who are immobilized owing to acute illness, and the treatment of adults with acute symptomatic spontaneous superficial-vein thrombosis of the lower limbs without concomitant DVT.
Blood perfusion that is not adequate to support normal organ function.
The coughing up of blood originating from the respiratory tract below the level of the larynx.
The study of flow properties of blood and its elements (plasma and formed elements, including red blood cells, white blood cells and platelets).
A condition that may occur when cardiac output is insufficient to meet the needs of the body and lungs. It is commonly referred to as congestive heart failure. The symptoms of heart failure usually develop quickly (acute heart failure), but they can also develop gradually, over time (chronic heart failure).
Abnormally low blood pressure, especially in the arteries of the systemic circulation.
Abnormally high blood pressure (the National Institute for Health and Care Excellence [UK] defines stage 1 hypertension as blood pressure measured in the clinic of 140/90 mm Hg or higher and subsequent ambulatory blood pressure monitoring daytime average or home blood pressure monitoring average of 135/85 mm Hg or higher).
Of unknown cause. Any disease that is of uncertain or unknown origin may be termed idiopathic (alternatively may be described as unprovoked).
Intermittent pneumatic compression
A therapeutic technique designed to improve venous circulation in the limbs of patients at risk of VTE. Used in medical devices such as air pumps, inflatable auxiliary sleeves, gloves or boots.
Rupture of a blood vessel within the brain, in areas such as the basal ganglia, cerebellum, brainstem or cortex.
A minimally invasive surgical procedure that enables the surgeon or gynaecologist to directly view the organs of the abdomen and pelvis.
Top-left chamber of the heart. In normal sinus rhythm, blood is squeezed out of the left atrium into the left ventricle (bottom-left chamber of the heart).
Left atrial appendage
Small ear-shaped sac in the muscle wall of the left atrium in which thrombi can form when blood is not pumped in the normal orderly way through the heart.
Left ventricular ejection fraction
The volume of blood pumped out of the left ventricle with each heartbeat or cardiac cycle, via the aortic valve into the systemic circulation.
Left ventricular systolic function
A measure of the functionality of the left ventricle to pump blood.
Magnetic resonance imaging
An imaging technique that uses the magnetic properties of hydrogen and its interaction with both a large external magnetic field and radio waves to produce highly detailed images of the human body (alternatively known as nuclear magnetic resonance, or NMR, imaging).
Damage to cardiac tissue caused by blockage of a coronary artery or coronary blood vessels. Depending on the extent of blockage, myocardial infarction is classified as non-ST-elevation (NSTEMI; partial artery blockage) or ST-elevation (STEMI; complete artery blockage).
Paroxysmal atrial fibrillation
Recurrences of atrial fibrillation that come and go and stop within 48 hours without any treatment.
Percutaneous coronary intervention
A procedure in which a catheter is inserted into a blocked coronary artery to restore arterial blood flow to the cardiac tissue.
Peripheral arterial disease
Reduced blood flow to extremities, usually the legs, caused by atherosclerosis (narrowing of arteries).
Having a toning effect on the veins. A term used to describe a class of drugs derived from plant extracts commonly used to treat chronic venous insufficiency. They are powerful antioxidants that work by stimulating release of chemicals within the vein walls to strengthen the circulation and reduce inflammation and fluid collection within the tissues.
The process by which platelets are stimulated by collagen exposed by a break in the endothelium or by thrombin generated in the coagulation cascade. A change in platelet surface occurs that supports the assembly of coagulation factors and the release of granular products, leading to platelet aggregation.
The period after childbirth – from 1 hour after delivery of the placenta through the first 6 weeks of an infant’s life.
A long-term complication of deep vein thrombosis characterized by pain, swelling and ulceration of the affected limb. Post-thrombotic syndrome is caused by venous hypertension, which leads to impaired venous return, reduced calf muscle perfusion and abnormal microvasculature function with increased tissue permeability.
A cell adhesion molecule expressed on platelets and endothelial cells, which can be used as a biomarker of thrombogenesis.
A platelet inhibitor (Effient® in the US; Efient®in the EU) developed by Daiichi Sankyo. Prasugrel, when co-administered with acetylsalicylic acid, has received regulatory approval for the prevention of atherothrombotic events in patients with acute coronary syndrome (i.e. unstable angina, non-ST segment elevation myocardial infarction or ST segment elevation myocardial infarction) undergoing primary or delayed percutaneous coronary intervention.
Pulmonary arterial hypertension
A progressive disease characterized by an increase of blood pressure in the pulmonary artery, leading to symptoms including shortness of breath, dizziness and fainting.
A potentially life-threatening complication of VTE, caused by an embolus in the pulmonary bed. Massive (high-risk) pulmonary embolism is usually defined by the presence of clinically overt right ventricular failure, resulting in haemodynamic compromise.
An operation that is performed to remove thrombi from the pulmonary arteries.
An event that occurs more than once in a patient over time. Examples may include a recurrent VTE (which could present as deep vein thrombosis or pulmonary embolism) or a recurrent acute coronary syndrome event.
Reduced ejection fraction
Lower-than-normal percentage of blood leaving the heart each time it contracts. An ejection fraction of ≥55% is considered normal and ≤50% is considered reduced (50–55% is borderline).
Any attribute, characteristic or exposure of an individual that increases the likelihood of developing a disease or injury. Transient risk factors are those that are temporary, such as major surgery, hospitalization and long-distance travel. Examples of persistent (permanent) risk factors include cancer or antiphospholipid syndrome.
An oral, direct Factor Xa inhibitor (Xarelto®) that has received regulatory approval for the prevention of venous thromboembolism in patients undergoing elective hip or knee replacement surgery, the treatment and secondary prevention of deep vein thrombosis and pulmonary embolism, the prevention of stroke and systemic embolism in adult patients with non-valvular atrial fibrillation, and the prevention of atherothrombotic events after an acute coronary syndrome with elevated cardiac biomarkers when administered with acetylsalicylic acid with or without clopidogrel. A phase IV non-interventional study has also been completed in patients receiving rivaroxaban for thromboprophylaxis after elective hip or knee replacement surgery.
Normal heart rhythm, as opposed to arrhythmia.
A wire mesh, stainless steel tube that holds a cardiac artery open and keeps it from narrowing again.
The development of a thrombus within an artery after implantation of a stent. A stent is a scaffold that is placed into diseased peripheral or coronary arteries. However, the body may have an immune response to the stent, leading to an inflammatory response and subsequent thrombosis.
A sudden interruption in the blood supply of the brain. Ischaemic stroke, the most common type of stroke, occurs when an artery supplying blood to the brain becomes blocked, causing the surrounding brain tissue to die.
The medical term for fainting, defined as a transient loss of consciousness and postural tone, characterized by rapid onset, short duration and spontaneous recovery.
An abnormally rapid or irregular heart rhythm, where the heart is not able to efficiently pump oxygen-rich blood to the body.
Abnormally rapid breathing (also known as polypnoea).
Surgical excision of a thrombus from a blood vessel.
A reduction in the platelet count below the normal lower limit (usually defined as 150–450 ×109/l).
Causing coagulation of blood or thrombi.
The use of drugs to break up or dissolve blood clots. A commonly used thrombolytic drug is tissue plasminogen activator (tPA).
An abnormality of blood coagulation that increases the risk of thrombosis. Otherwise known as a hypercoagulable or prothrombotic state, thrombophilias may be hereditary (i.e. protein C or S deficiency; Factor V Leiden) or acquired (environmental factors such as age, surgery or cancer).
Thromboplastin reagents are used to monitor oral anticoagulant therapy with vitamin K antagonists for patients with thromboembolic disorders.
The formation of a blood clot, or thrombus, inside a blood vessel. If this clot breaks loose and gets carried by the bloodstream to obstruct blood flow in another vessel, it becomes known as a thromboembolism.
A platelet aggregation inhibitor (Brilique®) produced by AstraZeneca, which when co-administered with acetylsalicylic acid, is approved for the prevention of atherothrombotic events in adult patients with acute coronary syndromes, including patients managed medically, and those who are managed with percutaneous coronary intervention or coronary artery by-pass grafting.
An important initiator of blood coagulation. In the extrinsic coagulation pathway, tissue factor binds Factor VIIa, leading to activation of coagulation Factors IX and X, which ultimately leads to fibrin formation.
Diagnostic procedure in which a probe emitting ultrasonic sound waves is passed down the oesophagus to assess the heart’s function. The sound waves are converted to an echocardiogram image of the heart.
Transient ischaemic attack
A form of stroke or mini-stroke that occurs when the symptoms last only a short time (usually a few minutes) and are resolved in less than 24 hours.
Hardening of vessels (atherosclerosis), caused by fatty deposits (plaques or atheroma). Subsequent vessel obstruction may lead to lack of blood supply to vital organs and tissues.
Having a toning effect on the veins. Venoactive drugs are a class of drugs derived from plant extracts commonly used to treat chronic venous insufficiency. They are powerful antioxidants that work by stimulating release of chemicals within the vein walls to strengthen the circulation and reduce inflammation and fluid collection within the tissues.
A condition that comprises deep vein thrombosis and pulmonary embolism.
A complication of deep vein thrombosis in which valves in the leg veins are damaged by the thrombus, thereby causing blood to flow the wrong way in the vein and eventually damaging the skin.
An imaging test commonly performed to check for the presence of a thrombus or abnormal blood flow inside the lungs (such as a pulmonary embolism), by evaluating the circulation of air (ventilation) and blood (perfusion) within the lungs using radioactive materials.