Glossary of Terms

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Elimination or removal of extra electrical pathways within the heart that cause fast or irregular heart rhythms. This is undertaken with administered cold (cryo-ablation) or radiofrequency (RF ablation).

A type of chemical (called a neurotransmitter) that transmits messages among nerve cells and muscle cells.

Acquired heart disease
Heart disease that arises after birth and can be due to disease of the myocardium, valves, coronary arteries or electrical pathways.

ACS (Acute Coronary Syndrome)
Medical term for acute conditions associated with possible or actual heart damage due to restricted blood supply. Incorporates unstable angina, NSTEMI and STEMI.  The latter two terms are also called a heart attack.

Acute Myocardial Infarction (AMI)
Medical term for a Heart Attack. The myocardium (heart muscle) is damaged, usually as a  result of acute restriction of the coronary blood supply.

Aerobic exercise
Repetitive, rhythmic exercise involving your muscles e.g. brisk walking, cycling and swimming.

AF (Atrial Fibrillation)
Irregular heart rhythm arising from the Atria.

A set of precise rules or procedures programmed for example into an implantable device (pacemaker, CRT, ICD or ILR) that are designed to solve a specific problem.

Air sacs in the lungs where oxygen and carbon dioxide are exchanged.

A kind of medicine (called an anti-arrhythmic) used to treat irregular heart rhythms such as atrial fibrillation and ventricular tachycardia. It works by regulating nerve impulses in your heart. Amiodarone is mainly given to patients who have not responded to other anti-arrhythmic medicines.

A sac-like protrusion from a blood vessel or the heart, resulting from a weakening of the vessel wall or heart muscle.

When the heart muscle does not get enough oxygen rich blood to meet the demand, the heart muscle experiences a hunger for more oxygen, and the patient experiences angina. Symptoms of angina include chest pressure, tightness, heaviness and discomfort in the arm, jaw, back, or neck.

X-ray picture of blood vessels and cardiac chambers using contrast.

Angiography (cardiac)
An x-ray technique in which dye is injected into the chambers of the heart or the arteries relating to the heart (including the coronary arteries) to assess structure and function.

Procedure using a balloon to stretch narrowed Coronary Arteries to improve the blood flow to the heart. Normally combined with insertion of a stent after the artery is stretched.

Angiotensin II receptor blocker
A medicine that is a vasodilator and lowers blood pressure by blocking the action of angiotensin II, a chemical in the body that causes the blood vessels to tighten (constrict). Used for treating hypertension and heart failure.

Angiotensin-Converting Enzyme (ACE) inhibitor
A medicine that is a vasodilator and lowers blood pressure by blocking the action of angiotensin II, a chemical in the body that causes the blood vessels to tighten (constrict). Used for treating hypertension and heart failure.

The ring around the base of a heart valve where the valve leaflet merges with the heart muscle.

Antiarrhythmic drugs
Medicines used to treat heart rate or rhythm disorders.

A drug used to reduce the risk of blood clots forming. There are two main types for oral use: Coumarins including warfarin and Phenindione, and Directly Acting Oral Anticoagulants (DOACs).

A medicine prescribed to reduce blood pressure.

Anti-platelet drug
A drug to slow blood clotting by reducing its stickiness. The commonest ones used currently are aspirin, clopidogrel and ticagrelor.

AntiTachycardia Pacing (ATP)
Short, rapid, carefully controlled sequences of pacing pulses delivered by an ICD and used to terminate a tachycardia in the atria or ventricles.

The main artery that receives blood from the left ventricle of the heart and flows to the body.

Aortic arch
The head and neck vessels arise from this part of the aorta, directing blood from the heart; the remainder of the blood then goes down to the rest of the body.

Aortic regurgitation (reflux)
Backwards leakage of circulating blood from the aorta into the left ventricle due to failure of the valve to close properly or to perforation. The leak can be trivial, mild, moderate, or severe.

Aortic stenosis
Also termed aortic valve stenosis. Narrowing of the opening of the aortic valve (the valve that regulates blood flow from the left ventricle into the aorta). This leads to obstruction of the valve that can be mild, moderate, severe, or critical. If severe can cause heart failure, syncope and angina on effort.

Aortic valve
The heart valve between the aorta and the left ventricle.

Arrest (Cardiac)
Cessation of the heart’s normal rhythmic electrical and/or mechanical activity which causes immediate haemodynamic compromise. A major cause of death.

An abnormal rhythm of the heart.

An x-ray using opaque dye to study arteries (usually coronary arteries).

Inflammation of the arteries.

One of the series of vessels that carries blood from the heart.

Artificial heart
A man-made heart. Also called a total artificial heart (TAH).

Ascending aorta
The first portion of the aorta, emerging from the heart’s left ventricle.

A drug used to help thin the blood and prevent clots forming.

A nonsurgical technique for treating diseased arteries with a rotating device that cuts or shaves away material that is blocking or narrowing an artery.

Build-up of fatty deposits in the blood vessels which restricts blood flow. Due to a number of risk factors.

Commonly called “hardening of the arteries”. Also termed arteriosclerosis. Due to a variety of conditions caused by fatty or calcium deposits in the artery walls causing them to thicken.

Atria (atrium – singular)
The two upper holding chambers of the heart.

Atrial fibrillation (AF)
An arrhythmia causing very fast and irregular beating of the atria (the upper two chambers of the heart).

Atrial flutter (AFL)
An arrhythmia causing a very fast organised beating of the atria (the upper two chambers of the heart).

Atrial Septal Defect (ASD)
A hole in the wall between the right and left atria (the two upper chambers of the heart), which can be small, moderate, or large in size.

Atrial Tachycardia (AT)
An arrhythmia causing a very fast organised beating of the atria (the upper two chambers of the heart).

Atrioventricular node (AV node)
Conducting tissue at the bottom of the right atrium in which electrical impulses must pass to reach the ventricles.

Atrioventricular (AV) Synchrony
The normal activation sequence of the heart in which the atria contract and then, after a brief delay, the ventricles contract. The loss of AV synchrony can have significant haemodynamic effects. Dual chamber pacemakers are designed to attempt to maintain AV synchrony.

Atrioventricular (AV) Block
An interruption of the electrical signal between the atria and the ventricles. Conduction can be delayed (first degree AV block),  or beats can be dropped (second degree AV block) or block can be complete (third degree block).

Automatic Implantable Cardioverter Defibrillator (AICD)
A surgically implanted device that checks the hearts electrical signals and delivers electrical therapy when it senses a dangerous heart rhythm.



Bacterial endocarditis
A bacterial infection of the lining of the heart’s chambers (called the endocardium) or of the heart’s valves.

Balloon angioplasty
A procedure to open a narrowed (stenosed) blood vessel using a balloon-tipped catheter threaded through the vessel. The balloon is inflated to open the diseased vessel.  For cardiology, most commonly is referring to angioplasty of a coronary artery.

Balloon valvuloplasty
A procedure to open a narrowed (stenosed) heart valve using a balloon-tipped catheter threaded through an artery and into the heart. The balloon is inflated to open and separate the diseased valve cups or leaflets.

Medication with multiple uses. Hypertension, angina, heart failure, following a heart attack and arrhythmias.  Helps to control the Heart Rate, Rhythm and Blood pressure.

A valve that has two cusps.

A procedure in which tissue samples are removed from the body for microscopic examination to establish a diagnosis.

Blood clot
A jelly-like mass of blood tissue formed by clotting factors and enmeshed blood cells. Clots stop the flow of blood from an injury. Clots can also form inside an artery when the artery’s walls are damaged by atherosclerotic build-up, possibly causing a heart attack or stroke.

Blood pressure
The pressure exerted by the heart in pumping blood.

Blood pressure cuff
A device usually placed around the upper portion of the arm to measure blood pressure.

Blood vessels
These are networks of hollow tubes that transport blood around your body.

Blue babies
Babies who have a blue tinge to their skin (cyanosis) resulting from insufficient oxygen in the arterial blood. This condition often indicates a heart defect.

This stands for Body Mass Index. A calculation is done to divide your weight by your height which will tell you whether you weight too much, too little or are the right weight for your height.

BNP (Brain Natriuretic Peptide)
Blood enzyme which can be measured to diagnose Heart Failure (HF)

Body mass index (BMI)
A number that indicates an increased risk of cardiovascular disease from a person being overweight. BMI is calculated using a formula of weight in kilograms divided by height in meters squared (BMI =W [kg]/H [m2]).

A procedure using radiation treatment to prevent re-blockage following angioplasty or stent placement in a coronary artery.

Bradycardia (Bradyarrhythmia)
A heart rate (HR) that is abnormally slow; commonly defined as under 60 beats per minute or a rate that is too slow to physiologically support a person and their activities.

Brain N Peptide
Blood enzyme which can be measured to diagnose Heart Failure (HF)

Bridge to transplant
Use of mechanical circulatory support to keep heart failure patients alive until a donor heart becomes available.

A sound made in the blood vessels or heart resulting from turbulence and due to narrowing (stenosis) or increased flow.

Bundle branch block
A condition in which parts of the heart’s conduction system is defective and unable to conduct the electrical signal normally. This can result in or be associated with heart block.



Calcium channel blocker (or calcium blocker)
A class of  drug used to treat angina, hypertension and sometimes arrhythmias.

Microscopically small blood vessels between arteries and veins that distribute oxygen-rich blood to the body’s tissues.

Medical term for all things to do with the Heart.

Cardiac amyloidosis
A disorder caused by deposits of an abnormal protein (amyloid) in the heart tissue, and often causing heart failure.

Cardiac arrest
Emergency where there is acute loss of cardiac output . A fatal condition unless resuscitation is successful.

Cardiac cachexia
A term for the muscle and weight loss caused by severe heart disease. It is often related to the depressed cardiac output associated with end-stage heart failure, but it can also occur with severe coronary artery disease.

Cardiac catheterisation
A diagnostic procedure in which a tiny, hollow tube or tubes (catheter) is inserted into an artery or vein in order to evaluate the heart and blood vessels. The evaluation includes measuring pressure and oxygen amounts in each chamber as well as angiography.

Cardiac doppler
A test using sound waves to produce images of the heart as it is beating.

Cardiac enzyme tests
Blood tests which measure the level of certain enzymes (usually Troponin but also CK) in your blood which are released by heart muscle (myocardium) during a heart attack.

Cardiac output
The amount of blood that goes through the circulatory system in one minute.

Cardiac rehabilitation
A structured programme of exercise and lifestyle management  to benefit patients that have had a myocardial infarction, coronary intervention, heart failure or heart surgery in the short and long term.

Cardiac resynchronisation therapy (CRT)
An implantable pacemaker device used when there is significant impairment of the heart conduction system and also of the left ventricle. Implanted under the skin overlying the chest, connected to two or three electrodes (pacing leads) that enter the heart via the veins.

A physician who specializes in the medical evaluation and treatment of heart diseases.

Medical term for all Heart care

A disease of the heart muscle that causes it to lose its pumping strength, often leading to heart failure.

Cardiopulmonary bypass
The process by which a machine is used to do the work of the heart and lungs so the heart can be stopped during surgery.

Cardiopulmonary resuscitation (CPR)
An emergency procedure that can maintain a person’s breathing and heartbeat. Depending on the circumstances, the team will be undertaking ventilation, chest compression, administering defibrillation shocks and giving drugs.

To do with the heart and blood vessels.

Cardiovascular Disease
A general term referring to conditions affecting the heart (cardio) and blood vessels (vascular system). May also simply be called heart disease. Examples include coronary artery disease, valve  disease, arrhythmia, peripheral vascular disease, congenital heart defects, hypertension, and cardiomyopathy.

Cardiovascular System
Describes the heart and all the blood vessels in the body.

Changing an abnormal heart rhythm into a normal one. This can occur spontaneously, by giving a medication, or by applying an electrical shock to the chest.

Carotid artery
The major arteries in the neck. Arise from the aortic arch and supply blood to the brain.

A long, thin, flexible tube; used during a cardiac catheterisation procedure to inject X-Ray dye, obtain blood samples, and measure pressures inside the heart and vessels; may also refer to the tube used to  drain the bladder. The tube may also be solid, i.e. not have a lumen, as used during an electrophysiology study including ablation.

Catheter ablation therapy
A procedure used to correct certain types of abnormal heart rhythms.

The process of inserting a catheter into a vein or artery and guiding it through the heart chambers and surrounding vessels for purposes of examination or treatment.

CCU Coronary Care Unit
Specialist unit of a hospital where you would be taken with an emergency Heart problem.

Pertaining to the blood vessels of the brain.

Cerebrovascular accident (CVA)
Also called a stroke. Injury to the brain tissue due to blocking of the blood supply by a clot (thrombus or embolus)or bleeding to some part of the brain.

CHD (Coronary Heart Disease)
Narrowing of the Coronary Arteries which supply Blood to the Heart.

A necessary fatty substance mainly made in the liver. Too much cholesterol or of the wrong sort increases the risk of coronary heart disease and other forms of atherosclerotic disease.

Cholesterol lowering drug
A drug to lower the blood cholesterol level. The most important drug class are the statins.

Chronotropic incompetence
The inability of the heart to increase its rate appropriately in response to increased activity or metabolic need, e.g., exercise, illness, etc.

Circulatory system
Pertaining to the heart and blood vessels, and the circulation of blood.

CK (Creatinine Kinase)
A Cardiac enzyme used to diagnose a heart attack.

A cramp like pain in the arms but more commonly the legs, caused by an inadequate supply of oxygen to the muscles, usually due to narrowed arteries or peripheral arterial disease (PVD).

Closed heart surgery
An operation that repairs problems involving the blood vessels or valves of the heart, not requiring the use of cardiopulmonary bypass.

A drug used to dissolve a clot in an emergency,for example during a heart attack or stroke. This is called thrombolytic therapy.

Coarctation of the aorta
A congenital heart defect that results in narrowing of the aorta.

Collateral circulation
Blood flow through small, nearby vessels in response to blockage of a main blood vessel.

Collateral vessels
New blood vessels created by the body to try and restore blood flow to an area when the blood vessel(s) that are already there are too small, narrowed, or blocked.

A procedure used to widen the opening of a narrowed heart valve using a balloon or surgical technique.

Computerised tomography scan (CT or CAT scan)
A non-invasive X-Ray scanning procedure that takes cross-sectional images of various parts of the body including the heart and circulatory system.

Conduction system
The electrical system, made up of special fibres inside the heart, that stimulates the heart to beat (contract).

Refers to conditions existing at birth.

Congenital heart defect
A heart problem present at birth, caused by improper development of the heart during fetal development.

Congestive heart failure
When the pumping action of the heart is not strong enough to meet the needs of your body, resulting in an accumulation of blood in the vessels leading to the heart and fluid in the body tissues including the lungs.

Coronary Angioplasty
More often called Percutaneous Coronary Intervention. A cardiac catheterisation procedure whereby a wire guided balloon is used to open up a stenotic coronary artery.

Coronary arteries
Two arteries arising from the aorta that arch down over the surface of the heart and divide into branches. They provide blood to the heart muscle.

Coronary Artery Anomaly (CAA)
A congenital defect in one or more of the coronary arteries of the heart.

Coronary Artery Bypass Grafting (CABG)
Surgical rerouting of blood around a diseased section of a coronary artery to restore blood flow. Done by grafting either a piece of vein from the leg, artery from the forearm  or using the internal mammary artery from under the breastbone.

Coronary Artery Disease (CAD) 
A narrowing of the arteries that supply blood to the heart. The condition results from a buildup of plaque and greatly increases the risk of a heart attack.

Coronary Heart Disease (CHD)
Narrowing of the coronary arteries which supply blood to the heart.

Coronary obstruction
A partial or complete obstruction (occlusion) of one of the coronary arteries, thereby hindering blood flow to the heart muscle. This can be due to thrombus, embolus, spasm or dissection.

Coronary spasm
A transient partial or complete obstruction (occlusion) of one of the coronary arteries, thereby hindering blood flow to the heart muscle. A rare clinical cause of angina.

Coronary thrombosis
Formation of a clot in one of the coronary arteries causing partial or complete occlusion.

Blueness of the skin, extremities, lips or tongue caused by a lack of oxygen in the blood.

Cyanotic heart disease
A birth defect of the heart that causes oxygen-poor (blue) blood to circulate to the body without first passing through the lungs.



Death rate (age-adjusted)
A death rate that has been standardized for age so different populations can be compared or the same population can be compared over time. Also cause standardised mortlality ration (SMR).

Deep Vein Thrombosis (DVT)
A blood clot in a deep vein in the calf.


Termination of an erratic, life-threatening arrhythmia of the ventricles by a high energy, direct current delivered asynchronously to the cardiac tissue, thereby enabling restoration of normal rhythm.

Machine used to deliver an electric shock to the heart to correct abnormal fast Heart Rhythms either in the setting of cardioversion or defibrillation.

A heart that is “flipped over,” so that the structures that are normally on the right side of the chest are on the left, and vice versa. The arteries and veins can be connected correctly; occurs due to an abnormality in heart development during pregnancy.

Diabetes (diabetes mellitus)
A disease in which the body doesn’t produce enough insulin or properly use insulin. This results in the body’s blood sugar levels to be too high and unstable.

Data gathered by an ICD or pacemaker to evaluate patient rhythm status, verify system operation, or assure appropriate delivery of therapy options.

The time during each heartbeat when the ventricles are at rest, filling with blood and not pumping.

Diastolic blood pressure
The second or bottom number in a blood pressure reading, taken when your heart is relaxed.

A health professional who can advise you on healthy eating and special diets.

A medicine made from the leaves of the foxglove plant. Digitalis is used to treat congestive heart failure (CHF) and heart rhythm problems (arrhythmias).

A condition in which the layers of an artery separate or are torn, causing blood to flow between the layers. Dissection most commonly occurs in the aorta and can cause sudden death.

Drugs that remove excess fluid from the body by increasing urine volume.  Used to lower Blood Pressure and Heart Failure.

Doppler ultrasound
A procedure that uses sound waves to evaluate the blood flowing in the heart, blood vessels, and valves.



ECG (Electrogcardiogram)
Test which fives a recording of the electrical activity of the Heart in the form of a graph.

Echocardiogram (Echo)
An ultrasound picture of the heart to assess the structure and function of the heart including the myocardium, chambers, valves and adjacent great vessels and tissues. See TOE and TTE.

A premature contraction of the atrium or ventricle earlier than the next expected normal sinus or escape rhythm beat. Caused by an abnormal electrical focus.

A collection of fluid in a closed cavity.

Ejection fraction (EF)
A measurement of the proportion of blood is pumped out of a filled ventricle in one beat. The normal rate is 50% or more.

Electrocardiogram Treadmill Test (ETT)
A recording of the Heart’s Rate and Rhythm while walking on a treadmill.

The connector to an external or internal lead conducting an electrical signal to detect or stimulate the heart. Leads are used to produce the Electrocardiogram (ECG). Also when placed internally in the body, leads are used to connect the heart to a Pacemaker, CRT or  Implantable Cardioverter Defibrillator (ICD).

Electromagnetic Interference (EMI)
Equipment and appliances that use magnets and electricity have electromagnetic fields around them. If these fields are strong, they may interfere with the operation of a Pacemaker or ICD.

Electrophysiological study (EPS) or Cardiac Mapping
A cardiac catheterisation procedure to provoke arrhythmias by electrical current stimulation to determine their origin, and test the effectiveness of medicines or ablation in their treatment.

Electrophysiological testing
A procedure (invasive or non-invasive) used to detect and give information about abnormal heart rhythms.

An embolism is the lodging of an embolus, a blockage-causing piece of material, inside a blood vessel. The embolus may be a blood clot (thrombus), a fat globule, a bubble of air or other gas, or foreign material. An embolism can cause partial or total blockage of blood flow in the affected vessel.

Surgical removal of plaque deposits or blood clots in an artery.

Inflammation of the interior surfaces of the heart including the valves. Usually due to blood born infection, especially bacteria, but can also be non-infective.

The membrane that covers the inside surface of the heart.

Enlarged heart (Cardiomegaly)
A state in which the heart is larger than normal because of heredity, long-term heavy exercise, or diseases and disorders such as obesity, high blood pressure, and coronary artery disease.

ETT Exercise Tolerance Test
Formal exercise test whilst monitoring the patient, blood pressure and ECG using either a treadmill or bicycle ergometer. Used for detecting coronary ischaemia, arrhythmias and level of cardiovascular fitness.



Familial hypercholesterolemia
An inherited condition in which members of a family are likely have very high cholesterol levels in their blood.

Fatty acids (fats)
Substances that occur in several forms in foods; different fatty acids have different effects on lipid profiles.

A drug used to bring down cholesterol and triglyceride levels in your blood.

A chaotic and unsynchronised quivering of the myocardium during which no effective pumping occurs. Fibrillation may occur in the atria or the ventricles.



Glyceryl trinitrate (GTN)
A drug which relieves and helps prevent angina attacks.

A small, bendable wire that is threaded through a catheter to act as a guide during  angiogram, angioplasty or stent procedures.

Transplanted tissue from one area of the body to another (As in use of a saphenous vein graft from the leg to bypass a coronary artery blockage during coronary artery bypass surgery).



The heart is a muscular organ which pumps blood through the blood vessels of the circulatory system. to provide the body with oxygen and nutrients, as well as assists in the removal of metabolic wastes. The heart is located in the middle compartment of the chest. The heart has 2 pumps, each composed of one atrium and one ventricle with the contraction sequence controlled by it’s own electrical system. There are heart valves ensuring that flow is only in one direction.

Heart assist device
A mechanical pump device that is surgically implanted to ease the workload of the heart.

Heart attack
See Myocardial Infarction.

Heart block
The electrical impulses causing the heart to beat are slowed or blocked along the pathway between the upper and lower chambers of the heart.

Heart Failure (HF)
When the pumping action of the heart is not strong enough to meet the needs of your body. Can present gradually or acutely…Chronic and Acute Heart failure respectively.

Heart Failure with Preserved Ejection Fraction (HFPEF)
When the ejection fraction (pumping action) of the left ventricle is normal but filling of this chamber is impaired. This can lead to heart failure. Can present gradually or acutely…Chronic and Acute Heart failure respectively.

Heart-lung machine (cardiopulmonary bypass)
An machine that oxygenates and pumps the blood during open-heart surgery.

A medicine used to slow the clotting of the blood.

Heart manual
A Manual given to patients which details their cardiac rehabilitation programme after heart illness. Sometimes used as an alternative to exercise class based rehabilitation.

Heart murmur
An abnormal heart sound caused by turbulent blood flow due in turn to an abnormal valve, increased flow through a normal valve or an abnormal communication  between the heart chambers or vessels.  Some heart murmurs are a harmless type called innocent heart murmurs.

Heart rate
The number of times the heart beats in a minute.

Heart rhythm
The pattern of the heartbeats.  The heart should beat regularly with an even space between each heartbeat.

Heart Support Group
A group of people who have gone through similar heart disease experiences who meet, talk and give each other support.

Heart transplant
Operation which involves replacing the diseased heart with the healthy heart of a donor.

High blood pressure (Hypertenson)
A common disorder in which blood pressure is abnormally high (typically a reading of 140/90 mm Hg or greater).

Holter monitoring

A technique for the continuous recording of electrocardiographic (ECG) signals, usually over 24 hours, to detect and diagnose ECG changes. (Also called ambulatory ECG monitoring.).

See high blood pressure.

Hypertrophic cardiomyopathy
Abnormally thickened and enlarged heart muscle that can cause impeded blood flow as well as lethal arrhythmias. Frequently due to a genetic abnormality.

Enlargement of tissues or organs because of increased workload.

Rapid breathing above that required for maintaining oxygen supply. Due to anxiety and much less commonly due to excess acid in the blood (diabetic ketoacidosis). Can lead to tingling of the extremities and faintness.

Low levels of glucose (sugar) in the blood.

Decreased movement of the myocardium during each heart contraction. It is associated with cardiomyopathy, heart failure, or heart attack.

Low blood pressure.

Less than normal content of oxygen in the organs and tissues of the body.




No known cause.

Any medicine that suppresses the body’s immune system. These medicines are used to minimize the chances that the body will reject a newly transplanted organ, such as a heart.

Implantable Cardioverter Defibrillator (ICD)
A device put inside the chest to deliver an electric shock to the heart to correct Ventricular Tachycardia (VT) and Ventricular Fibrillation (VF).

Implantable Loop Recorder (ILR)
An electronic device that is surgically implanted over the chest wall to detect arrhythmias. The ILR can be interogated by remote monitoring.

An area of tissue permanently damaged by an inadequate supply of oxygen due to a blockage or interruption in the supply of blood. See myocardial infarction.

Infective endocarditis
An infection of the heart valves and the innermost lining of the heart (the endocardium), usually due to blood born infection, especially bacteria.

Positive inotropes: Any medicine that increases the strength of the heart’s contraction.  Negative inotropes: Any medicine that decreases the strength of the heart’s contraction and the blood pressure.

Internal mammary artery
A durable artery in the chest wall often used as a bypass graft in coronary artery bypass surgery.

Into the muscle.

Intravascular Ultrasound (IVUS)
A combination of echocardiography and cardiac catheterisation. A miniature utrasound device on the tip of a catheter is used to generate images inside the heart and blood vessels.

Into a vein.

Introducer sheath
A catheter-like tube that is placed inside a patient’s vessel during an interventional procedure to help the doctor with insertion and proper placement of the actual catheter.

Decreased flow of oxygenated blood to an organ due to obstruction in an artery. It can lead to tissue damage and, if prolonged, death or infarction of tissue in the organ.

Ischaemic heart disease (IHD)
Also called coronary artery disease and coronary heart disease. Often results in narrowing of the coronary arteries, thereby causing a decreased blood supply to the heart.

Ischaemic stroke
A type of stroke that is caused by blockage in a blood vessel.

Isosorbide mononitrate
A drug used to help prevent angina attacks and sometimes used in the treatment of heart failure.



An external or internal lead conducting an electrical signal to detect or stimulate the heart. Leads are used to produce the Electrocardiogram (ECG). Also when placed internally in the body, leads are used to connect the heart to a Pacemaker, CRT or  Implantable Cardioverter Defibrillator (ICD).

Left atrium (LA)
The upper left-hand chamber of the heart. It receives oxygen-rich (red) blood from the lungs via the pulmonary veins, and then sends this blood to the left ventricle via the mitral valve.

Left ventricle (LV)
The lower left-hand chamber of the heart. It receives oxygen-rich (red) blood from the left atrium and pumps it into the aorta via the aortic valve. The blood in the aorta is then distributed  to all parts of the body.

Left ventricular Assist Device (LVAD)
A mechanical device that can be placed outside or inside the body. An LVAD does not replace the heart—it “assists” or “helps” it pump oxygen-rich blood from the left ventricle to the rest of the body.

Left ventricular dysfunction
Describes the status of the left ventricle when it is not pumping or filling correctly.

Left ventricular hypertrophy (LVH)
When the left ventricle is too thick walled. Most commonly due to hypertension but also cab be due to aortic valve disease or cardiomyopathy.

An injury or wound. An atherosclerotic lesion is an injury to an artery; also termed hardening of the arteries.

Fatty substances in your blood including cholesterol and triglycerides.

A lipid surrounded by a protein; the protein makes the lipid soluble (can be dissolved) in the blood.

Low density lipoprotein (LDL)
The body’s primary cholesterol-carrying molecule. High blood levels of LDL increase a person’s risk of heart disease by promoting cholesterol attachment and accumulation in blood vessels; hence, the popular nickname “bad cholesterol.”

Paired organs within the chest cavity that enable the exchange of blood gases with the surrounding air; the uptake of oxygen for bodily needs, and also the excretion of carbon dioxide which is a waste product made as the oxygen is used up by body tissues.



Magnetic resonance imaging (MRI)
A technique that produces images of the heart and other body structures by measuring the response of certain elements (such as hydrogen) in the body to a magnetic field. MRI can produce detailed pictures of the heart and vessels, both still and moving images, as well as an assessing tissue structure and viability.

Marfan syndrome
An inherited condition associated with lax tissues and affecting many parts of the body including the bones, eyes, heart and aorta.

Maze surgery
A type of heart surgery that is used to treat chronic atrial fibrillation by creating a surgical “maze” of new electrical pathways to let electrical impulses travel easily through the heart. Also called the Maze procedure.

Mechanical valve
An artificial valve used to replace a diseased or defective valve, most often the aortic valve. Usually constructed of titanium and pyrolytic carbon. Patients with a mechanical valve require anticoagulation medication to prevent clots from forming on the valve.

Median sternotomy
An incision in the centre of the chest, from the top to the bottom of the breastbone, used to gain access for most major forms of heart surgery.

Minimally Invasive Surgery (MIS)
Unlike traditional open heart surgery which is very invasive, MIS means a limited incision to gain entry to the body. Used for off bypass cardiac surgery, transcatheter aortic valve implantation and aortic stents.

Mitral regurgitation (reflux)
Backward leak of circulating blood from left ventricle to left atrium due to failure of the mitral valve to close, or to prolapse or to perforation. The leak can be trivial, mild, moderate, or severe.

Mitral stenosis 
Also termed mitral valve stenosis. Narrowing of the opening of the mitral valve. The obstruction can be mild, moderate, or severe.

Mitral valve
The valve which controls the flow of blood from the left atrium to the left ventricle.

Mitral valve surgery
This can take the form of repair, splitting of the valve if narrowed (valvotomy), or valve replacement.

mm Hg
An abbreviation for millimeters of mercury. Blood pressure is measured in units of mm Hg—how high the pressure inside the arteries would be able to raise a column of mercury.

Units used for measuring the level of different lipids, and many substances including electrolytes. Usually refers to levels in the blood but measurements can be from other body fluids.

Monounsaturated fat
A type of ‘good’ fat which can help lower blood level of LDL cholesterol. It is found in some foods such as olive oil, walnut oil, canola oil, rapeseed oil, avocado and in some margarines and spreads.

The total number of deaths from a given disease in a population during an interval of time, usually a year.

Myocardial Infarction (MI)
Medical term for a Heart Attack. The myocardium (heart muscle) is damaged, usually as a  result of acute restriction of the coronary blood supply.

Myocardial ischaemia
Insufficient blood flow to part of the heart that can lead to damage of heart tissue. Depending on the severity it can present as angina, breathlessness, and as a heart attack.

A rare condition in which the heart muscle (myocardium) becomes inflamed as a result of infection, toxic drug poisoning, or auto-immunity disorders.

The middle and the thickest layer of the heart wall, composed of cardiac muscle.  It contracts to pump blood out of the heart and then relaxes as the heart refills with returning blood.



Refers to the death of tissue within a certain area.

A chemical found in tobacco smoke, probably harmless, alongside many harmful chemicals in the smoke that cause vascular disease and cancers.

Nicotine replacement products
Products containing nicotine (patches, gum, smoke inhalers and nasal sprays) to help you stop smoking.

A medicine that helps relax and dilate arteries; often used to treat cardiac chest pain (angina).

Noninvasive procedure
A diagnostic effort or treatment that does not require entering the body or puncturing the skin.

Non-ST Elevation Myocardial Infarction (NSTEMI)
The most common type of heart attack. An NSTEMI does not produce an ST-segment elevation on an electrocardiogram. See also STEMI.

NOGA (Cardiac Navigation System)
Three-dimensional mapping of electromechanical function of the heart to assess blood flow.



The condition of being significantly overweight. It usually applies when a person is 30% or more over ideal body weight. See Body Mass Index. Obesity puts a strain on the heart and can increase the risk of developing high blood pressure and diabetes.

An opening, orifice, or passage that is completely blocked. For cardiology this usually relates to a blocked vessel, artery more often than a vein.

Collection of extracellular fluid in tissues that can lead to swelling and oedema, for example seen in the lungs, legs and abdomen in congestive cardiac failure.

Omega 3
A type of fatty acid found in fish oils. Eating these can help prevent blood clotting and help reduce triglyceride levels.

Open heart surgery
An operation in which the chest and heart are opened surgically while the bloodstream is diverted through a heart-lung (cardiopulmonary bypass) machine.

Oxygen saturation
The extent to which the haemoglobin is saturated with oxygen. (Haemoglobin is a protein in the red blood cells that binds with oxygen and carries it to the organs and tissues of the body.)

A method of measuring the oxygen content of blood.



A device used when the heart rate or conduction system is too slow, and implanted under the skin overlying the chest, connected to one or two electrodes (pacing wires) that enter the heart via the vein circulation. The electrodes are used to listen to the heart (sensing) and also to deliver electrical impulses to make the heart contract if necessary (pacing), thereby restoring the natural contraction sequence of the heart.

Pacing lead (wire)
The means to conduct the electrical signals to and from an an electronic device (pacemaker, ICD or CRT). Temporary pacing is sometimes required and this uses an external pacing lead and pacemaker generator box.

An abnormal pulsing or beating  sensation felt in the chest or sometimes heard in the ears, caused by an irregular or rapid heart rhythm.

Passive smoking
Where non smokers inhale other people’s smoke. Causes the same ill health effects as low cigarette smoking.

Patent Ductus Arteriosus (PDA)
A congenital defect in which the opening between the aorta and the pulmonary artery does not close after birth.

Patent Foramen Ovale (PFO)
An opening between the left and right atria of the heart. Everyone has a PFO before birth, but in 1 out of every 3 or 4 people, the opening does not close naturally, as it should, after birth.

Percutaneous Coronary Intervention (PCI)
Also called coronary angioplasty. A cardiac catheterisation procedure whereby a wire guided balloon is used to open up a stenotic coronary artery. Usually accompanied by the deployment of a stent to maintain the patency of the opened artery.

Pericardial effusion
A build up of excess fluid in the pericardial sac between the heart and the membrane that surrounds it.

A diagnostic and therapeutic procedure that uses a needle to draw fluid from the pericardial sac.

An inflammation or infection of the sac which surrounds the heart which in turn can cause accumulation of fluid termed a pericardial effusion. Multiple causes. Often seen after myocardial infarction or open heart surgery.

The outer fibrous sac that surrounds the heart.

Peripheral vascular disease (PVD)
Disease of the blood vessels that supply blood to the limbs.

A health professional who helps you to improve mobility and general fitness.

A deposit of fatty (and other) substances in the inner lining of the artery wall as part of the atherosclerosis disease process.

Small cells found in the circulating blood that when activated deposit on the vessel wall to assist in clotting.

Polyunsaturated fats
A type of ‘good’ fat found in foods from plant and fish such as cornflower oil, sunflower oil, fish oil and some margarines and spreads.

Positron Emission Tomography (PET)
A scan that uses radioactive versions (radioisotopes) of natural elements to image various tissues and organs. For cardiology mainly used to identify areas of myocardial ischaemia and infarction.

Primary PCI
When Percutaneous Coronary Intervention (PCI) is undertaken as the first treatment for a STEMI Heart Attack.

Prevention.For example measures to prevent coronary disease, diabetes and endocarditis.

Pertaining to the lungs and respiratory system.

Pulmonary artery
The blood vessel connecting the right ventricle to the lungs, allowing oxygen-poor (blue) blood to receive oxygen.

Pulmonary oedema
A condition in which there is fluid accumulation in the lungs. Most often caused by an incorrectly functioning heart. Seen in failure of the left ventricle and in congestive heart failure.

Pulmonary embolism
A condition in which a blood clot lodges in the pulmonary artery or it’s branches. The clot may form in situ but much more commonly has formed elsewhere in the body and travelled to the lungs.

Pulmonary valve
The valve which controls blood flow from the right ventricle to the pulmonary artery. The valve can be diseased,; stenosed or leaky or both.

Pulmonary vein
Four blood vessels that carry newly oxygenated blood from the lungs back to the left atrium of the heart.

Pulse oximeter
A non-invasive device that measures the amount of oxygen in the blood. Normal oxygen saturation in the arteries is 94 to 100 percent.

Pulmonary valve
The valve between the pulmonary artery and the right ventricle having three cusps that open and close with the heartbeat.

Pulmonary vein
Four blood vessels that carry newly oxygenated blood from the lungs back to the left atrium of the heart.

Pulse oximeter
A non-invasive device that measures the amount of oxygen in the blood. Normal oxygen saturation in the arteries is 94 to 100 percent.



Rapid Access Chest Pain Service (RACPS)
System for referral from Primary Care to Secondary Care for the assessment of chest pain.

Radial artery
The radial artery in the wrist is often used as the preferred entry point for the catheter in a PCI. Also called trans-radial access.

Radionuclide imaging
A test in which a harmless radioactive substance usually injected into the bloodstream is scanned. For cardiology mainly used to identify areas of myocardial ischaemia and infarction.

Backward flow of blood through a defective heart valve. All healthy heart valves are one -way valves (very small leaks can be normal).

Rehabilitation Programme
A programme to aid recovery following a heart attack, heart surgery, coronary intervention or heart failure in the short and long term. The program provides education about exercise, lifestyle, relaxation and treatments.

Remote monitoring
A system to enable remote interrogation of pacemakers, ICD and CRT devices from the patient’s home. The results are networked to the relevant cardiac service. Remote monitoring has the potential for early detection of arrhythmias and device malfunction and of saving clinic visits.

Pertains to the kidneys.

Restoration of blood flow to an organ or tissue. What happens after successful Percutaneous Coronary Intervention or Thrombolysis.

The re-closing or re-narrowing of an artery after an interventional procedure such as Percutaneous Coronary Intervention.

Life saving action for a cardiac arrest or respiratory arrest (circulation or breathing cessation).

A procedure to open up or bypass blockages in existing blood vessels. For cardiology this usually refers to the coronary arteries and either opened up by PCI or bypassed,  Coronary Artery Bypass Grafting (CABG).

Rheumatic fever
A disease due to a streptococcal infection causing rashes, joint pain and swelling, nodules on the arms, and a movement disorder. Usually occurs in childhood. Late manifestation is rheumatic heart disease.

Rheumatic heart disease
A disease of the heart (mainly affecting the heart valves) caused by rheumatic fever.

Right atrium
The upper right chamber of the heart, which receives oxygen-poor (blue) blood from the body and pumps it to the right ventricle via the tricuspid valve.

Right ventricle
The lower right chamber of the heart, which receives oxygen-poor (blue) blood from the right atrium and sends it to the pulmonary artery via the pulmonary valve.

Risk factor
An element or condition involving a certain hazard or danger. When referring to heart and blood vessels, a risk factor is associated with an increased chance of developing cardiovascular disease, including stroke. Risk factors include smoking, high blood pressure, raised cholesterol, physical inactivity, obesity, diabetes, gender,  ethnic background, age and a family history of heart disease.



Saturated fat
Type of fat found in foods of animal origin and a few of vegetable origin; they are usually solid at room temperature. Abundant in meat and dairy products, saturated fat tends to increase LDL cholesterol levels, and it may raise the risk of certain types of cancer.

Septal defect
A hole in the wall between the atria or the ventricles (upper or lower heart chambers). Can be inherited or acquired.

The muscle wall between the atria or ventricles (upper or lower heart chambers).

A catheter-like tube that is placed inside a patient’s vessel during an interventional procedure to help the doctor with insertion and proper placement of the actual catheter. Also called an introducer sheath.

A condition in which body function is impaired because of low blood flow or circulating volume. This may be caused by blood loss or by a disturbance in the function of the circulatory system.

A connection to allow blood flow between two locations. It can be congenital or it can be placed surgically.

Sick sinus syndrome
The failure of the sinus node to regulate the heart rhythm. Can be associated with slow and or fast heart rates.

Silent ischemia
Episodes of myocardial ischaemia that are not accompanied by chest pain.

Sinus Node
The heart’s natural pacemaker located in the right atrium. Electrical impulses originate here and travel through the heart, causing it to contract (beat).

Sinus bradycardia
A normal but slow heart rhythm.

Sinus rhythm
A normal heart rhythm in which each electrical impulse originates in the sinus node, and proceeds through the rest of the electrical conduction system to cause a normal contraction sequence.

Sinus tachycardia
A heart rhythm that originates in the sinus node and proceeds through the rest of the electrical conduction system, but is faster than normal.

A mineral essential to life found in nearly all plant and animal tissue. Table salt (sodium chloride) is nearly half sodium.

An instrument used to measure blood pressure.

The generic name for a family of prescribed cholesterol-lowering drugs.

ST Elevation Myocardial Infarction (STEMI)
ST-segment-elevation myocardial infarction. The more severe form of the 2 types of heart attack. See also NSTEMI. A STEMI produces a characteristic elevation in the ST segment on an electrocardiogram.

Narrowing or constriction of a blood vessel or valve in the heart or circulatory system.

A device made of expandable, metal mesh that is placed (by using a balloon catheter) at the site of a narrowed vessel. For cardiology, this is usually part of a percutaneous coronary intervention procedure. The stent is expanded by the balloon and left in place to keep the artery open.

An obstruction or narrowing of an opening (as in coronary artery stenosis) or valve.

A metallic scaffold placed over a delivery balloon catheter that is positioned in the narrowed site of an artery.

A surgical incision made in the breastbone (sternum) and in relation to cardiology as a prelude to open heart surgery.

Stress Test
Using stress (exercise, drugs, cold or mental stress) to provoke coronary ischaemia or arrhythmias.

A sudden disruption of blood flow to the brain, either by a clot or a leak in a blood vessel. This can leave transient or permanent damage and can be mild, moderate or severe. See Transient ischemic attack (TIA).

Subarachnoid hemorrhage
Bleeding from a blood vessel on the surface of the brain into the space between the brain and the skull. Can cause or be associated with a stroke.

Subclavian arteries
Two major arteries (right and left) that receive blood from the aortic arch and supply it to the arms.

Under the tongue. Some medicines are taken this way.

Sudden cardiac death (SCD)
Death due to cardiac causes within 1 hour of the onset of symptoms, with no prior warning. Usually caused by ventricular fibrillation.

Supraventricular tachycardia (SVT)
A regular rapid heart rate (150-250 beats per minute) that is caused by events triggered in areas above the heart’s lower chambers (the ventricles); see also supraventricular tachycardia (SVT).

A temporary, insufficient blood supply to the brain which causes a loss of consciousness. Usually part of a faint but can be due to a serious arrhythmia.

The time during the heartbeat when the ventricles are pumping blood, either to the lungs or to the body.

Systolic blood pressure
The highest blood pressure measured in the arteries. It occurs when the heart contracts with each heartbeat.




Rapid beating of either or both chambers of the heart, usually defined as a rate over 100 beats per minute. Can be due to a normal rhythm or an arrhythmia.

Also called cardiac tamponade. An emergency situation that occurs when blood or fluid fills the pericardial sac surrounding the heart, preventing the heart from beating effectively.

TAVI (Transcatheter Aortic Valve Implantation)
TAVI is an alternative for individuals at high risk for conventional surgical replacement of aortic valves. It involves inserting a crimped replacement valve on a catheter. Once in position in it is either balloon-inflated or self-expanded to replace the diseased valve.

Telemetry unit
A small box with wires attached to ECG patches on the chest; used to continuously monitor the rhythm via radio transmission to healthcare professionals for evaluation.

Thrombolytic therapy
Intravenous or intra-arterial medicines that are used to dissolve blood clots in an artery.

A blood clot.

Tissue valve
An artificial valve, made from animal tissues (pig or cow) and, mounted on a frame with cloth surround, enabling it to be sewn into the heart. There is no requirement for anticoagulation once a tissue valve is inserted unless there is another indication.

TOE (Transoesophageal Echocardiography)
A type of ultrasound which produces images of the Heart viewed from the Oesophagus (gullet) and used to assess the structure and function of the heart unimpeded by the bone and lungs which affects imaging through the chest wall (transthoracic echocardiography).

Transient ischemic attack (TIA)
A stroke-like event that lasts only for a short time and is caused by a temporarily blocked blood vessel.

Replacing a failing organ with a healthy one from a donor.

Tricuspid valve
The structure that controls blood flow from the heart’s upper right chamber (the right atrium) into the lower right chamber (the right ventricle).

Tricuspid valve disease
Tricuspid regurgitation is very common and usually due to heart failure. Stenosis of this valve is rare.

The most common fatty substance found in the blood; normally stored as an energy source in fat tissue. High triglyceride levels often accompany other risk factors for heart disease, such as obesity.

A Cardiac Enzyme used to diagnose a heart attack. Used now as early means of detection of myocardial damage and in preference to  CK (Creatinine Kinase).

TTE (Transthoracic Echocardiography)
A type of ultrasound which produces images of the heart viewed from the chest wall and used to assess the structure and function of the heart.



A diagnostic tool used to evaluate organs and structures inside the body with high-frequency sound waves. See TTE and TOE.

Unsaturated fat
A type of ‘good’ fat found mainly in foods from plants and fish sources. They include monounsaturated fats and polyunsaturated fats.

Unstable angina
At the lower end of the Acute Coronary Syndrome spectrum. Angina that is of new onset, more readily provoked and/or occurring at rest and without a rise in Troponin.



Controls the flow of blood into and out of the heart.

Valve regurgitation
Also called valve insufficiency or incompetence. The one-way valve fails to close completely and leaks.

Valve replacement
An operation to replace a heart valve that is either sufficiently stenosed or regurgitant to cause symptoms or affect the outlook. See open heart surgery and TAVI.

Valve stenosis
This can occur in any of the four heart valves and can be congenital or acquired.  Most commonly the aortic valve is affected and due to age-related degeneration.

The “doors” between the chambers of the heart that allow blood to move forward and prevent it from moving backward. The heart valves are called tricuspid, pulmonary, mitral, and aortic and control the flow of blood into and out of the heart.

Valvular heart disease
When at least one of the four heart valves is diseased or damaged.

Repairing a heart valve by surgery or by using a catheter with a balloon.

Varicose vein
Any vein that is abnormally dilated (widened).

Pertaining to blood vessels.

A medication that dilates a blood vessel through relaxation.

A medication that raises blood pressure.

Vasovagal syncope
Blackout due to a sudden drop in blood pressure, with or without a decrease in heart rate, which is caused by a dysfunction of the nerves controlling the heart and blood vessels.

Any one of a series of blood vessels of the vascular system that carries blood from all parts of the body back to the heart. The blood carried is oxygen-poor and is borne to the lungs for replenishment.

Vena Cava
The large veins (superior and inferior vena cava) that return all blood to the heart from the body.

An artificial breathing machine.

The two main pumping chambers of the heart, the left serving the body circulation and the right serving the pulmonary circulation.

Ventricular fibrillation (VF)
A life-threatening arrhythmia. Impulses are sent at a fast irregular rate causing the ventricles to fibrillate or quiver. There is no effective output from the heart and the condition is lethal unless treated effectively and rapidly. See Cardiac Arrest and Resuscitation.

Ventricular septal defect (VSD)
An abnormal opening in the wall between the right and left ventricles, which can be small, moderate, or large in size. Can be congenital or acquired. Can occur after a heart attack.

Ventricular tachycardia (VT)
A serious arrhythmia generated in the ventricles and characterised by a very fast regular heartbeat.

A feeling of dizziness or spinning.

VF Ventricular Fibrillation
Life threatening irregular heart rhythm.



Wolff-Parkinson-White Syndrome
A condition in which an extra electrical pathway connects the atria (two upper chambers) and the ventricles (two lower chambers). It may cause a rapid heartbeat.



A diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.



Y wave
The wave in the atrial and venous pulse curves reflecting rapid filling of the ventricles just after the atrioventricular valves open.



A protein found in fibroblasts, smooth muscle and pigmented retinal epithelium.


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