Glossary Of Terms - A

Ablation ACE inhibitor ACS Acute Coronary Syndrome Adrenaline AED Automatic External Defibrillator Alcohol unit Allergy
Alphablocker Ambulance - when to call Anaemia Analgesic Angina* Antihistamine Angiography, angiogram
Angioplasty Angiotensin sensitivity test Aorta Apnoea Apple a day Artery Aspirin
Atrial fibrillation Average

Abbreviations. See also Prescription abbreviations, and/or the alphabetic place in this glossary where an abbreviation occurs (eg LDL). Here are some other symbols and abbreviations.

1/7 = one day, or one day each week.
1/52 = one week or one week each year. 3/12 = 3 months. 12/12 = all of a year.
< means less than and not equal to.
> means greater than, ie more than and not equal to.
< and <= both mean less than or equal to.
> and >= both mean greater than or equal to.
| means or.
+ and +- both mean plus or minus, the value that follows is one standard deviation.
* sometimes means multiply.

ABPM = Ambulatory blood pressure monitor. ACE inhibitors = Angiotensin converting enzyme inhibitors. ACS = Acute coronary syndrome. AED = Automatic external defibrillator. AF = Atrial fibrillation. AHSN = Academic Health Science Network. AICD = Automatic implantable cardioverter defibrillator. Alcapa = Anomalous Left Coronary Artery for the Pulmonary Artery. AOYA = Age of your arteries. AST = Angiotensin sensitivity test. Also Aspartate aminotransferase. AV node = Atrioventricular node. AVPU - see under Consciousness. AVR = Aortic valve replacement - See Valve surgery.
bd = Twice per day. BE = Base excess. BHFNC See British Heart Foundation National Centre. BIPAP = Biphasic positive airway pressure. BIVAD = Left and right ventricular assist device. BMI = Body mass index. BMJ The British Medical Journal is a journal for UK doctors BP = Blood pressure. BPM = Beats per minute - see heart rate. Bx = Biopsy.
CA = Cancer. CABG = Coronary artery bypass graft. CAD = Coronary artery disease. CBP = Cancelled by patient. CCF = Congestive cardiac failure. CCR = Critical Care Recovery. CE = Carpentier Edwards (type of valve). CF = Cystic fibrosis. CHB = Complete heart block. CHC = Community Health Council. CHD = (to the public) Coronary heart disease or (to medics) Congenital heart disease. CHF = Chronic heart failure, under HF terms. CHOL = Cholesterol. CI = Cardiac index. CMU = Chest Medical Unit. CMV = Cytomegalo virus. CNS = Central nervous system. COPD = Chronic obstructive pulmonary disease. COX. See COX under NSAIDs. CPAP = Continuous positive airway pressure. CPB = Cardio-pulmonary bypass. CPR = Cardio-pulmonary resuscitation. CQC = Care Quality Commission. CRP = C-reactive protein (blood test) - see Polymyalgia. CSF See Cerebrospinal fluid under Meningitis. CT = Computerised tomography. CTO = Chronic total occlusion. CVA = Cerebrovascular accident. CVD = Cardiovascular disease. CVP = Central venous pressure. CVS = Cardiovascular system. CVVH = Continuous veno-venous haemofiltration. CVVHD = Continuous veno-venous haemodiafiltration. CXR = Chest X-Ray. CYA = Cyclosporin A.
DC = Direct current. DCM = Dilated cardiomyopathy. DEAFF = Detection of early antigen by fluorescent foci. DES means drug-eluting stent, explained under Stent. DHA = Docosahexaenoic_acid, explained under Fatty acids. DI = Desaturation index. DM = Diabetes mellitus. DNA = Did not attend. DNR = Do not resuscitate. DOA = Dead on arrival. DOB = Date of birth. DOD = Date of death. DVT = Deep vein thrombosis.
EBV = Epstein-Barr virus. ECG = Electrocardiogram. ECHO = Echocardiogram. See factsheet Echocardiogram*. ECMO = Extra corporeal membrane oxygenation. EDP = End diastolic pressure. EDS = Excessive daytime sleepiness. EF = Ejection fraction. Effk+ = Effervescent potassium. EN = Enteral nutrition. EPA = Ecosapetanoic acid, a fatty acid. EPAP = Expiration position airways pressure. ESBL = Extended Spectrum Beta Lactamase. ESPRIT = Efficacy and Safety of PRescribing In Transplantation. ESR = Erythrocyte sedimentation rate (blood test). ETT = Endotracheal tube.
F1 and F2 are first and second year after qualifying as a doctor. FI02 = Fractional inspired oxygen. FBC = Full blood count (blood test). FEV1 = Forced expired volume in 1 second. FFP = Fresh frozen plasma. FH = Family history. FOB = Fibreoptic bronchoscopy. FRR = Financial Risk Rating. FTGA = Foundation Trust Governors Association. FU = Follow up. FVC = Forced vital capacity.
g = gram or gravity acceleration. GI = Glycaemic Index. GP = General Practitioner. GTN = Glyceryl trinitrate. GTT = Global Trigger Tool. GUCH = Grown-up Congenital Heart Disease.
H+ = Hydrogen ion concentration. Hb = Haemoglobin. HCM = Hypertrophic cardiomyopathy. HDL - See Cholesterol HDL. HF = Heart failure. HLTx = Heart lung transplant. HR = Hazard Ratio. HR = Heart Rate. HRCT = High Resolution Computerised Tomography. Hrly = Hourly. HS = Heart Sounds. HSV = Herpes simplex virus. Ht = Height. HT = Hypertension. HTx = Heart transplant. Hx = History.
IABP = Intra-aortic balloon pump. ICD = Implantable cardio-defibrillator. ICP = Integrated care pathway. ID = Intradermal (injection). IDDM = Insulin dependent diabetes mellitus. IgG = Immunoglobulin G. IgM = Immunoglobulin M. IHD = Ischaemic heart disease. ILR = Implantable loop recorder - see Event monitor. IM = Intramuscular. IMA = Internal Mammary Artery. INR = International normalised ratio. IPAP = Inspiratory positive airway pressure. IPPV = Intermittent positive pressure ventilation. ISMO and ISMN = Isosorbide mononitrate. IV = iv Intravenous - See Intravenous infusion. IVC = Inferior vena cava. IVs = Intravenous drugs.
JET = Junctional ectopic tachycardia. JVP = Jugular venous pressure.
kPa = Kilopascal (pressure).
L = Left. LA = Left atrium. LAD = Left anterior descending coronary artery. LAP = Left atrial pressure. Lat = Lateral. LBBB = Left bundle branch block. Lcx = Left circumflex - See Coronary arteries. LDL - see Cholesterol LDLLFT = Liver function tests. LIMA = Left internal mammary artery. LLL = Left lower lobe. LSE = Left sternal edge. LTOT = Long term oxygen therapy. LUL = Left upper lobe. LV = Left ventricle. LVAD = Left ventricular assist device. LVEDP = Left ventricular end diastolic pressure. LVEF = Left ventricular ejection fraction - see Ejection fraction. LVF = Left ventricular failure. LVHF = Left ventricular heart failure - under HF terms.
MAOI = Monoamine oxidase inhibitor, under Brand names of drugs and scroll down. MAP = Mean arterial pressure. MC&S = Microscopy culture and sensitivity. mcg = Microgram. mg = Milligram. MI = Myocardial infarct or myocardial infarction. MIBI = Methoxyisobutylisonitrile scan. Micro = Microbiology. ml/hr = Millilitres per hour. mm = millimetre(s). mmHg = Millimetres of mercury. MND = Motor neurone disease. MINAP stands for Myocardial Ischaemia National Audit Project - See under National Institute for Cardiovascular Outcomes Research.  MR = Mitral regurgitation. MRI = Magnetic resonance imaging. MRSA = Methicillin-resistant staphylococcus aureus. MS = Mitral stenosis. MSSA = Methicillin-Sensitive Staphylococcus Aureus - See under MRSA. MSU = Mid-stream urine. MUGA = Multiple gated acquisition or cardiac blood pool study. MVR = Mitral valve replacement. MVT = Movement time.
n-3 fatty acid = omega-3 fatty acid; scroll down to name. Similarly for n-6 fatty acid. NAD = No abnormality detected. NBM = Nil by mouth. NBx = Needle biopsy. NG = Nasogastric. NHS = National Health Service. NICOR = National Institute for Cardiovascular Outcomes Research. NIDDM = Non insulin dependent diabetes mellitus. NIPPV = Nasal intermittent positive pressure ventilation. NOF = National Obesity Forum. NOS = Not otherwise specified. NPU = Not passed urine. NREM = Non-rapid eye movement sleep. NSAID = Non-steroidal anti-inflammatory drug.
OA = Osteoarthritis. OB = Obliterative bronchiolitis. obs = Observations. od = One a day. O+D = Oesophagoscopy + dilation. O/E = On examination. OGD = Oesophagogastrod uodenoscopy. OM = Obtuse marginal. om = Each morning. on = Each night. OPD = Out Patient Department. OSA = Obstructive sleep apnoea.
PA = Pulmonary artery. PAC = Pre-admission clinic. PaC02 = Arterial partial pressure of carbon dioxide. PAD = Public access defibrillator - see under AED. PALS = Patient Advice and Liaison Service. Pa02 = Arterial partial pressure of oxygen. PAP = Pulmonary arterial pressure. PAT = Paroxysmal atrial tachycardia. PCA = Patient controlled analgesia. PCI = Percutaneous coronary intervention. PDA = Patent ductus arteriosis. Pdi = Transdiaphragmatic pressure. PE = Pulmonary embolus. PEEP = Positive end expiratory pressure. PEFR = Peak expiratory flow rate. PEG = Percutaneous endoscopic gastrostomy. PET = Positron emission tomography. PFI = Private Finance Initiative. PFT = Pulmonary function test. pH = potential of hydrogen. PM = Post mortem. PMA = Patient’s medication on admission. PMH = Past medical history. PMLR = Percutaneous myocardial laser revascularisation. PMR = Percutaneous myocardial revascularisation or Polymyalgia rheumatica. PND = Paroxysmal nocturnal dyspnoea - see Dyspnoea. PO = by mouth. Poes = Oesophageal pressure. Post op = Post operative. POT = Portable oxygen therapy. PP = Private patient. PPCI = Primary Percutaneous Coronary Intervention. PPP = either Preserve life, Prevent deterioration, Promote recovery - aims of First aid; or Position, Pressure, Pad & bandage - for bleeding in First aid. PR = Per rectum. Pre-med = Pre-operative medication. Prn = Whenever needed. Psg = Polysomnography. PT = Prothrombin time. Pt = Part, Patient. PTCA = Percutaneous transluminal coronary angioplasty = stent through groin. PtcC02 = Transcutaneous carbon dioxide tension. PTE = Pulmonary Thromboendarterectomy. PUFA = polyunsaturated fatty acid. PV = Pulmonary vein. PVI = Pulmonary vein isolation. PVO = Peripheral vascular disease. PVR = Pulmonary vascular resistance.
QALY = Quality-adjusted life years. qds = Four times a day.
QIPP = Quality, Innovation, Productivity and Prevention. R = Right. RA = Right atrium. RAP = Right atrial pressure. RATG = Rabbit antithymocyte globulin. RBBB = Right bundle branch block. RCA = Right coronary artery. REM = Rapid eye movement. RHO = Rheumatic heart disease. RIMA = Right internal mammary artery. RLL = Right lower lobe. RLS = Restless legs syndrome. RMl = Right middle lobe. RNI = Reference Nutrient Intake. RTA = Road traffic accident. RTD = Retired. RTI = Respiratory tract infection. RUL = Right upper lobe. RV = Right ventricle. RVAD = Right ventricular assist device. RVEDP = Right ventricular end diastolic pressure. RVF = Right ventricular failure. RVHF = Right ventricular heart failure - under HF terms. Rx = Treatment.
Sa02 = Arterial oxygen saturation. SADS = Sudden arrhythmic death syndrome. SAN = Sino-atrial node. SARS stands for Severe Acute Respiratory Syndrome - see respiratory tract under lung. SBE = Sub-acute bacterial endocarditis. SCS = Spinal cord stimulation. SD = Standard deviation. S-ICD = Subcutaneous Implantable Cardio-Defibrillator. SIMV = Synchronised intermittent mandatory ventilation. SIP = Service Improvement Programme. SLE = Systemic lupus erythematosus. SNP = Sodium nitroprusside. SOA = Swelling of ankles. SOB = Shortness of breath. SOBOE = Shortness of breath on exertion / exercise. SP02 = Spectrophotometry oxygen saturation. SR = Sinus rhythm or slow release. SSI = Surgical site infection. SSRI = Selective serotonin reuptake inhibitor, under Brand names of drugs and scroll down. STD = Sexually transmitted disease. SURT = Simple unprepared reaction time. SV = Stroke volume. SVC = Superior vena cava. SVG = Saphenous vein graft. SV02 = Mixed venous oxygen saturation. SVR = Systemic vascular resistance, SAVR = Surgical valve replacement. SVT = Supraventricular tachycardia.
TB = Tuberculosis. Tbbx = Trans bronchial biopsy. TCA = Tricyclic antidepressants, Tricyclics, see under Brand names of drugs and scroll down. TCI = To come in. tds = Three times a day. TE = Expiratory time. temp = Temperature. TENS machine see Transcutaneous Electrical Nerve Stimulation. TIA = Transient ischaemic attack. TMLR = Transmyocardial laser revascularisation. TMR = Transmyocardial revascularisation. TOE = Transoesophageal echo. Toxo = Toxoplasmosis. TPG = Trans-pulmonary gradient. TPN = Total parentral nutrition. TPR = Temperature, pulse and respiration. TTOs = Drugs to take home. TVR = Tricuspid valve replacement. Tx = Transplant.
UARS = Upper airways resistance syndrome. U/S = Ultrasound.
VAD = Ventricular assist device. VF = Ventricular fibrillation. VRE = Vancomycin resistant enterococci. VSD = Ventricular septal defect. VT = Ventricular tachycardia - see Tachycardia. VTE = Venous thrombo-embolism.
WBC = White blood count (blood test). WL = Waiting list. Wt = Weight.
yr = Year.

Ablation is a general term with three meanings.
1 The surgical removal of an organ, structure, or a part of such. This can apply to any part of the body – it is not heart-related.
2 The melting or wearing away of an expendable part – eg of the heat shield of a spacecraft during reentry.
3 The wearing away of part of a rock or glacier.
See ablation for AF under Atrial Fibrillation.

Radiofrequency Ablation of Atrial Flutter is a treatment to correct an abnormal heart rhythm. Through a vein in the groin at the top of a patient's right leg and/or a vein under a collarbone, wires are passed to the heart. These are used to ablate, ie burn away, the exact pathway in the heart that is causing the atrial flutter.

ABPM. See Ambulatory BP monitor.

Access to medical records. See Medical records.

ACE inhibitor stands for Angiotensin converting enzyme inhibitor.

Acetone is a chemical with formula CH3COCH3; a colourless, volatile, liquid; used in the manufacture of some other chemicals; and also used as a solvent & thinner for paints, varnishes and lacquers.

Acid. See acid under Organic chemistry.

Acute Coronary Syndrome, ACS, is used as a general term for unstable angina with related conditions.

More widely, it is a term used to describe a range of conditions associated with sudden, reduced blood flow to the heart, ie sudden and spontaneous blockage or near blockage of one or more coronary arteries, including heart attack and unstable angina. ACS often causes severe chest pain or discomfort, especially unstable angina, which is unpredictable angina unrelated to exercise and coming and going even when the patient is resting. One condition under the umbrella of acute coronary syndrome is myocardial infarction (heart attack) – when cell death results in damaged or destroyed heart tissue, the heart muscle being unable to function properly. Even when acute coronary syndrome causes no cell death, the reduced blood flow alters heart function and indicates a high risk of a heart attack. Acute coronary syndrome is a medical emergency that requires prompt diagnosis and care. Treatment goals include improving blood flow, treating complications and preventing future problems. Sources: Also: MINAP 2014-15 annual report. Myocardial Ischaemia National Audit Project – How the NHS cares for patients with heart attack. 52pp. Published about late January 2017. Also:

Acute heart failure. For acute heart failure see under Heart failure terms.

Addiction means compulsive use of a drug and/or continual craving, usually leading to physical and/or psychological dependence – eg for a particular drug, nicotine by smoking, or caffeine in coffee and/or tea.

Adjuvant is a drug that enhances the effect of another drug. Eg aluminium is added to some vaccines to increase the immune response, so increasing the protection.

Adrenocorticotrophin. See under Stress.

Adrenaline is a hormone produced in the medulla (innermost centre part) of the adrenal glands in response to stress. It increases the heart rate and blood pressure; and raises the levels of glucose and lipids. See Epinephrine and under Stress.
The two adrenal glands are at the anterior end of each kidney.

Adverse effect means an unwanted side effect. Adverse reaction means the same.

AED. See automatic external defibrillator.

Age of Your Arteries AoYA. Provided by AstraZeneca UK and supported by the leading patient groups HEART UK and The British Cardiac Patients Association (BCPA), the Age of Your Arteries campaign was a health initiative that aims to raise public awareness of atherosclerosis, which is the build up of fatty plaques in our arteries and is the main underlying cause of cardiovascular disease.

It was launched 26th May 2007. For the press release and leaflet on this, see BCPA website SiteMap (at foot of the window) and scroll down to AoYA entries.

AICD See automatic implantable cardioverter defibrillator.

Alkali. See alkali under Organic chemistry.

Alcohol unit. An alcohol unit is roughly* the alcohol in half a pint of beer or lager, or roughly* a glass of wine, or roughly* a single measure of spirits. *Here 'roughly' means that some pub measures are more than one unit – particularly of wines and spirits, because in recent years the volumes of the measures and/or glasses have increased, and also because different alcoholic drinks differ in their alcohol content.

Current (2011) recommendations are that men should not to have more than 21 alcohol units per week, and women not more than 14. Research trials suggest preferably have about 3 to 4 units per week - see below. Recently (2011) some experts have recommended not more than 11 units per week.

Some experts believe that for adults one glass of a chardonnay or of red wine every day or two – but not more alcohol than that – reduces the risk of coronary heart disease.

A large amount of alcohol any evening may significantly raise your blood pressure the following day.

See also red wine under Apple.

A research trial showed that for adults one glass of a chardonnay or of red wine every day or two – but not more alcohol than that – reduces the risk of coronary heart disease. The research trial, which finished in 2004, compared various groups of people who drank different amounts of alcohol, and the analysis found the following to be statistically significant.

(a) Men who drink three or more units every day and/or are binge drinkers are more likely to have a stroke than non-drinkers.

(b) Men who are at lowest risk of stroke were men who drank one or two units three or four times per week. They had slightly lower risk both than non-drinkers and than those who drank one or two units of alcohol every day.

(c) Men with the lowest total risk for any or all three of CHD, strokes and diabetes taken together are those whose alcohol consumption was limited to one drink unit, or at most two, about every other day, with little benefit shown above three or four drinking days per week.

Although this research was only based on analysis of men, experts expect the patterns for women are likely to be similar. See also Stroke.

Another research trial in 2004 compared two groups of men and women aged from 30 to 74. One group drank 300 ml of red wine, which is just over one unit, daily for four weeks; and, as a control group for comparisons with, the others drank red grape extract or water.

● In the red wine group the HDL of each person typically increased by 11% to 16% of its value at the start. No significant HDL difference was observed in the control group.

● In the red wine group the amount of fibrinogen of each person typically decreased by 8% to 15%. No significant fibrinogen difference was observed in the control group.

Other research trials have shown that moderate* red wine and/or white wine such as chardonnay is protective against CHD, but other forms of alcohol are not. However the explanations may lie in other factors such as differences in the lifestyles and habits of the people who prefer the different kinds of drinks. *The term moderate here implies about one unit per day or two, from three to seven units per week, but not more.

Excess alcoholic drinks every day gradually affect the liver, and once liver damage has happened it is not reversible.

Also beers and similar drinks contain energy – far more than drinks of wine with the same alcohol content. So drinking beers and similar drinks tends to lead to becoming overweight. Drinking wine instead is preferable as regards avoiding being overweight.

Alcohol – Hospital alcohol gel for rubbing on hands does not prevent C diff. But it does prevent MRSA.

ALCAPA Alcapa stands for Anomalous Left Coronary Artery for the Pulmonary Artery. This is a very rare congenital disease that causes the body to pump blood the wrong way round the heart. Only 10% of such babies survive if not diagnosed and treated by surgery before their first birthday.

Algia means pain or a painful condition, from Greek. In combination -algia is also used with other words, eg myalgia = muscle pain; neuralgia = severe spasmodic pain along one or more nerves; odontalgia = tooth pain. See analgesia = not able to feel pain; analgesic = a substance that produces analgesia.

Alimentary canal is the whole system for digestion – mouth, oesophagus (tube from mouth to stomach), stomach, duodenum, intestines, pancreas, liver, gallbladder, rectum, and anus.

Allergy. An allergy is when a substance triggers an undesirable or over-reaction in the immune system. An allergic reaction means the same, particularly when the reaction does not occur on the first exposure but appears on a later one. See Ambulance when to call for when to call an ambulance.

The immune system protects the body by eliminating foreign substances that it does not recognize – eg microorganisms such as bacteria or viruses. It produces antibodies.

When the body first gets a new foreign substance, one kind of white blood cell – called lymphocytes – produces the antibodies. These attach themselves to a second kind of white blood cell – called mast cells. See mast cells.

If the body gets the same foreign substance again, the mast cells release chemicals called mediators, eg histamine. This can produce a rash, swelling, narrowing of airways, and/or a drop in blood pressure. The antibodies and mediators protect against infections; but unfortunately may be triggered inappropriately – which is then an allergy.

When it is impossible for the patient to avoid the substance triggering the allergy, treatment is usually by antihistamines and/or corticosteroids, and/or drugs that minimize the symptoms. See antihistamine under Histamine.

A steroid is any of various naturally occurring fat-soluble organic compounds and that contain 17 carbon atoms arranged in four rings. Steroids include adrenal and sex hormones, sterols, bile acids, and D Vitamins. They have a physiological action.

A sterol is any of a group of mainly unsaturated solid alcohols of the steroid group – such as cholesterol and ergosterol. They are present in the fatty tissues of plants and animals.

Ergosterol is a crystalline plant sterol, formula C28H43OH. It is synthesized by yeast from sugars or derived from ergot; and converted to vitamin D2 by ultraviolet radiation.

Alphablockers block nerve signals that would trigger narrowing of blood vessels. Several alphablockers are available.

Brand names of Alphablockers
Doxazosin - Brand names Cardura, Doxadura
Tamsulosin - Brand names Flomaxtra XL, Omnic MR, Stronazon MR

Ambulance and when to call. Some people advise that in general one should call an ambulance without delay if someone has any of the following life-threatening conditions.

● Not breathing/cardiac arrest

● Severe chest pain – such as unexpectedly, or a heart attack, or angina that continues after initial treatment

● Difficulty in breathing

● Loss of consciousness

● Severe loss of blood

● Severe burns and scalds

● Choking

● Fitting/convulsions

● Drowning, and/or

● Severe allergic reactions.

At a road traffic accident, as soon as you know how many casualties and the severity of their injuries – eg whether conscious or unconscious, and whether likely to be stretcher cases – get someone to phone for an ambulance and tell them a brief description of the injuries.

If the patient's condition does not fall into the list above it may still be that an ambulance is required. Such patients are classified as having a serious condition but not immediately life-threatening. A good example is a lower limb fracture. This is a stretcher case and definitely requires an ambulance. But the call would not be classified as immediately life-threatening unless the patient was for example also unconscious or bleeding severely. So the ambulance service need a brief but accurate description of the condition of the patient so they can classify it correctly.

This is important for three reasons.

● Resources are allocated to calls based on how serious they are rather than when the call was received. So if an ambulance is on its way to a broken leg but a chest pain call comes in nearby it will be sent to the chest pain call with another vehicle from further away being sent to the broken leg.

● If an ambulance is more than 8 minutes away then whenever possible Community Responders or off-duty ambulance staff will be deployed to 'immediately life-threatening calls' but not normally to other calls.

● Paramedics have AED equipment in ambulances to restart a patient's heart. They have oxygen, and have facilities to insert a cannula, a small tube that can be inserted eg into a vein and administer appropriate injections. They also have ECG monitoring and recording equipment. Ambulance crews have also been trained to diagnose those heart conditions that are best treated by taking the patient straight to a hospital such as Papworth with facilities for operating without delay. This gives far better chances of survival than taking such patients to a nearer hospital that does not have such facilities. The ambulance and hospital facilities have continually improved over recent decades, and increased the chance of survival and recovery from heart attacks and other conditions.

Because a first aider generally does not have these facilities, an ambulance should be called as soon as possible. Before the provision of any AEDs, sadly few cardiac arrest casualties survived. But AEDs and better first aid training have increased the survival rate. Villages that are a long way from the nearest ambulance station often have trained paramedics among their population. The ambulance control can call them to go to the emergency and they will get there before the ambulance. They should have the equipment needed for most emergencies. See Community responders.

The rule for an Automatic external defibrillator (for a lay person) is that it should only be attached to a patient who is both not responding and not breathing. Lay people should not check for a pulse – it will waste time and may be incorrect. Provided the patient is both unresponsive and not breathing, the AED can be relied upon to deliver a shock only if necessary.

Before the provision of any AEDs, sadly only 2-3% of UK cardiac arrest casualties survived. But AEDs, changed ambulance facilities, and better first aid training have increased the survival rate.

Villages that are a long way from the nearest ambulance station often have trained paramedics among their population. The ambulance control can call them to go to the emergency and they will get there before the ambulance. They should have the equipment needed for most emergencies. See Community responders.

Ambulatory blood pressure monitor, ABPM is an arm cuff connected to a box that can be worn on the belt, and the whole monitors the patient's blood pressure eg for a day. This avoids the effect of artificially high BP readings when at a doctor's surgery. It can save many GP appointments.

Amide An amide is a chemical compound formed from an organic acid by the substitution of an amino group (NH2, NHR, or NR2) for the OH of a carboxyl (COOH) group – see amide under Organic chemistry.

Amino acid See amino acid under Organic chemistry.

Aminoacetic acid See glycine.

Amnesia See under Collapse.

Anaemia. Iron deficiency is called anaemia. See iron for why the body needs it and tablets. Anaemia symptoms include: pallor, fatigue, breathlessness, and palpitations. It may also cause apathy, irritability, lower resistance to infections, intellectual performance, and behaviour.

Anaemia is a deficiency of red blood cells and/or in their haemoglobin content. Haemoglobin combines reversibly with oxygen and so is important for transporting oxygen in the blood to tissues. Symptoms of anaemia include breathlessness – short of breath, pallid complexion, fatigue, and general lack of energy. These are all caused by the lungs, heart, and/or blood circulation not supplying enough oxygen.

Vitamin B12 is needed to avoid anaemia. Folic acid, iron, potassium, and cobalt are also needed.

Pernicious anaemia symptoms are a feeling of weakness and eg: lesions of the spinal cord, sore tongue, numbness in arms and legs, and/or diarrhoea – all caused by the deficiency of red blood cells and of haemoglobin, and hence not enough oxygen being carried.

Anaesthetic. An anaesthetic is a drug that produces either a local loss of sensations of touch or pain over a small part of the body, or temporary unconsciousness – such as for an operation or some other procedure that would otherwise be painful.

An anaesthetist is a doctor specializing in anaesthetics, which is the science of such drugs.

Analgesia is the inability to feel pain. See also algia.

Analgesic. An analgesic is a chemical that reduces pain – a painkiller. It means relieving pain by drugs. Pain is a symptom, not a disease. Longterm relief therefore needs treatment of the underlying cause. If the underlying cause cannot be cured, longterm analgesic treatment, eg by drugs, may be needed.

Nerve endings detect damage to body tissues from disease or injury, and send signals to the brain. The brain's interpretation of these signals may depend on the patient's psychological state, eg may be worse with anxiety or fear. Support and reassuring explanation may help the patient to bear the pain and/or may relieve it.

Analgesics divide into opioids – the strongest pain relievers, and non-opioids.

Non-opioids = NSAIDs and non-NSAIDs. The non-opioids divide into Non steroidal anti-inflammatory drugs, NSAIDs, eg aspirin; and non-NSAIDs eg paracetamol.

NSAIDs relieve pain, inflammation, and/or swelling – usually of joints and/or muscles and reduce fever.

Non-opioids block the production of prostaglandins, so the nerve endings that would send pain messages to the brain are prevented from being stimulated. Thus eg paracetamol relieves pain and inflammation.

Analgesic pain-relief products named Co- – eg Co-codamol, Co-codaprin – contain both an opioid and a non-opioid; the non-opioid part may be either paracetamol or another NSAID. But codeine is just an opioid analgesic. See also Co_proxamol.

Analysis, analysing means examining in detail, breaking down into parts or components, finding out about each component, and understanding how the parts work together.

Anaphylaxis is a severe allergic reaction. The symptoms are swelling of the throat or tongue, hives, and/or trouble breathing. When it strikes, life is at risk. So time is critical. It may cause shock.

Many people carry a lifesaving device that gives an easy-to-use injection of Epinephrine. See also under Shock for symptoms and treatment of shock.

Aneurysm. See Aortic aneurysm.

Angina See separate factsheet on angina. This includes stable and unstable angina.

Angina is a chest pain – an uncomfortable feeling in the chest that is usually brought on by exercise or emotional upset. For some people it is hardly a pain at all, but for others it can be severe. The commonest complaint is of a heaviness or tightness in the middle of the chest. The pain may spread to the left shoulder, left arm and hand; neck, throat, jaw, back and/or stomach. The patient may be temporarily short of breath, and/or feel weak and/or anxious. Also called angina pectoris.

Angina is a built-in warning device, telling you that your heart is trying to do too much and that you must take it easier.

Angina is most often caused by the gradual narrowing of the arteries of the heart by materials being deposited in their walls. Over many years, these deposits increase until they reach a size where they actually restrict the flow of blood through the arteries.

When a patient's body is at rest and the heart is beating at its normal resting rate, sufficient blood passes into the heart muscle to nourish it. Under exercise or strong emotion the heart is put under strain by being made to beat faster and a point is reached when the flow of blood and the oxygen it carries is insufficient to meet the increased demand of the heart muscle. Those muscles are starved of oxygen so cannot function properly, and this produces pain.

Anyone who unexpectedly gets such pain or symptoms should rest immediately and call an ambulance if either:

● it is not stable angina; or

● if both it is stable angina that the patient has had before and understands, and it does not respond within a few minutes to rest.

Angiography, angiogram. Cardiologists often recommend an angiogram for patients with angina. Under local anaesthetic, a fine catheter tube is introduced into a femoral artery in the groin and passed along the body’s arteries to the coronary arteries. A dye is injected to give an X-ray picture of the blood flow and arteries. This will show both where and how much the coronary arteries are narrowed.

The whole procedure can be done in a day. The results are stored in a computer system without the need for Xray film. The surgeon and staff can control the frequency of the images – eg having far fewer images per second than used to be needed with Xray film, and the Xray dose is much lower than ten or 20 years ago. The process takes about 30 to 45 minutes. With improved methods of treating the femoral artery wound – eg Angio-seal®, the patient typically needs only a couple of hours afterwards in the hospital.

Angioplasty means passing a catheter along an artery to the heart. The angioplasty entry is often made into the femoral artery at the patient’s groin, or sometimes in the arm or wrist. A local anaesthetic is usual.

An angioplasty catheter is a long, flexible, slender or very-fine hair-like hollow guide wire that can be fed along an artery – eg the femoral artery. It is used either to help place a balloon or stent in position, or to inject a dye. The cardiologist guides the wire by viewing an X-ray picture. The wire may be made so its natural shape near the end is a slight curve, so by rotating it when an artery junction is reached, it can be guided into the correct route. See Balloon angioplasty, Cardiac catheterisation, Coronary angioplasty and stent insertion, and Rotablation.

Angio-Seal® is a vascular closure device fitted to a femoral artery wound. Its parts are absorbed within 90 days. It has an anchor that goes inside the artery hole, a suture that comes towards the skin and is trimmed below the skin, and a collagen sponge around the suture that is pushed to the outside of the artery to block the hole. There is no latex and it is MRI compatible. It is absorbed within the next 90 days.

Angiotensin converting enzyme inhibitors, ACE inhibitors. ACE inhibitors are drugs used to reduce high blood pressure and/or to help the heart to pump more efficiently and effectively. To inhibit means to restrain, hinder, prohibit, prevent or stop something that would normally otherwise happen - eg a chemical reaction. ACE inhibitors act on enzymes and dilate blood vessels throughout the body, thus reducing the blood pressure by lowering the pressure against which the heart has to pump. ACE inhibitors are beneficial where the heart failure is due to abnormalities in how well the left ventricle pumps. They also prolong life. Many different ACE inhibitors are available.  

Captopril - Brand name Capoten
Enalapril - Brand name Innovace
Lisinopril - Brand names Carace, Zestril
Ramipril - Brand name Titrace

If you are taking the dose once a day, it is best to take it in the morning. If you are taking more than one dose per day, then space them out evenly through the day.

When you first start taking ACE inhibitors or if your doctor increases the dose, you may experience a dizzy or faint feeling until your body adjusts to the dose. This should soon pass if you sit or lie down for a while. However, if this happens you should inform your doctor.

Some ACE inhibitors, eg perindopril, have anti-blood-clotting properties and restore the smooth lining of the arteries, stopping the build-up of fats in the artery walls.

Side effects of ACE inhibitors are relatively rare. They include dizziness, headache, fatigue, diarrhoea, muscle or joint pains, dry cough (see above) and rash or skin itch. If you experience any side effects, contact your doctor.

Angiotensin II blocker. Angiotensin II is a powerful hormone that constricts blood vessels. An Angiotensin II blocker blocks that action, so relaxes the blood vessels. This makes the arteries and veins slightly larger calibre, reducing the heart workload and lowering blood pressure.

A new drug, valsartan, brand name Diovan®, was trialled internationally about 2003 – involving 15,000 patients in 54 hospitals. It was found to be as effective as other angioitensin-II blockers in reducing the risk of second or third heart attacks, but without giving patients a dry cough. Previously there was nothing to give to such patients. As an angiotensin II blocker, it is used to treat high blood pressure, hypertension. It may also be used after a heart attack to reduce the risk of further complications. It blocks the angiotensin II hormone from reducing the width of blood vessels, so they relax and become wider and thus helps to reduce blood pressure and thus helps the heart.

Angiotensin sensitivity test AST tests for sensitivity to angiotensin II. It works by infusion of angiotensin II amide into a vein at the elbow. The result is positive if an increase of diastolic blood pressure of a specified rate or more occurs.

Anomalous Left Coronary Artery for the Pulmonary Artery. See Alcapa.

Antagonist means having the opposite effect, eg a drug that blocks something.

Anterior means situated at or towards the front of the body. Opposite of posterior.

Antibiotic means a substance that kills particular bacteria or fungi.

Antibodies are chemicals produced and used by the lymphocytes (a particular kind of white blood cell) in the immune system to help the body to overcome infection, disease, allergy, or unwanted foreign substances – viruses and bacteria. They are blood proteins. Anti- means against.

Anticoagulant. Anticoagulants are drugs to reduce or prevent blood coagulating or clotting in blood vessels, or to prevent a thrombosis or embolus causing trouble in the bloodstream.

The main treatment used to be warfarin, which required frequent monitoring of the INR. Newer types of anticoagulants are also available and are becoming increasingly common. These include:
● rivaroxaban (Xarelto)
● dabigatran (Pradaxa)
● apixaban (Eliquis)
● edoxaban (Lixiana)

Heparin is an anticoagulant that is used to prevent blood clots forming, and/or to prevent existing clots getting bigger or breaking and producing an embolus.

Warfarin is an anticoagulant drug, and is named after Wisconsin Alumni Research Foundation and Coumarin. Coumarin is an anticoagulant. Warfarin is usually taken by mouth.

Antidepressant is a drug to help people who are depressed, or have occasional feelings such as despair, lethargy, loss of libido, and/or poor appetite. Some antidepressants take 10-14 days before having much noticeable effect, and up to two months to reach their full effects. So the dose should not be changed, particularly not increased, before more than that time. Normally the brain has enough neurotransmitters. If not, an antidepressant may be prescribed. An antidepressant works by increasing the neurotransmitters in the brain, stimulating brain cells and thus improving mood.

Mirtazapine® is an antidepressant drug. It works by increasing the amounts of two relevant chemicals that occur naturally in the brain. These are norepinephrine (also or previously called noradrenaline), the fight or flight hormone, and serotonin (which helps control mood and body functions that work each day – eg sleep pattern). Betablockers interact with and nullify the effects of norepinephrine.

Side effects of Mirtazapine. Here * means discuss with your doctor if severe; and ** means discuss with your doctor in all cases. The more common side effects of Mirtazapine include increased appetite & weight gain*; drowsiness or fatigue*; and swollen ankles** or feet**. Rare side effects include dizziness*; headache*; nightmares*; jaundice**; fever** and/or sore throat**.

Antihistamine. See Antihistamines under Histamine, Corticosteroids. They are treatments for all kinds of allergic reactions.

They are subdivided according to their chemical structure – so each subgroup has different actions and/or characteristics. Topical creams applied to the skin mainly act on the muscles surrounding the small blood vessels that supply the skin and mucous membranes – eg brand name Anthisan. Other antihistamines act on airways in the lungs thus reducing congestion and breathlessness; or on the brain giving a sedative effect and suppressing the coughing and vomiting mechanisms.

Antihistamines block the action of histamine on H1 receptors, which are in various body tissues eg the small blood vessels in the skin, nose and eyes. The antihistamines help to prevent the dilation of the vessels – thus reducing swelling, watering, and redness.

Antihistamines also reduce the secretions from tear ducts / glands and nasal passages. Each tear duct (lacrimal duct) produces the fluid in each eye associated with tears, and which keep the surface correctly slightly damp. Nasal passages are passages behind the nose.

Side effects of antihistamines Antihistamines may cause drowsiness – affecting coordination, and hence cause clumsiness; and may have side effects such as dry mouth, blurred vision, and difficulty passing urine. So it may be advisable to avoid driving. They also increase or cause similar effects to alcohol, sleeping drugs, opioids, and anti-anxiety drugs.

See histamine, corticosteroids.

Antihypertensive. An antihypertensive is a chemical that reduces high blood pressure, and may be taken longterm to maintain lower blood pressure.

Antihypertensive drugs work in various ways – acting on different parts of the body to reduce blood pressure.

- Alphablockers block nerve signals that would trigger narrowing of blood vessels.

- Centrally-acting antihypertensives affect the brain mechanism that controls blood vessel size.

- Betablockers that are heart related reduce the force / pressure at each heartbeat.

- Diuretics cause the kidneys to reduce blood volume.

- ACE inhibitors, Angiotensin converting enzyme inhibitors, act on enzymes and dilate blood vessels.

- Vasodilators and calcium channel blockers act on the muscles of the walls of arteries to prevent narrowing.

Antioxidant. An antioxidant is a chemical that protects against damage by free radicals. Equivalently, an antioxidant retards deterioration by oxidation – especially of fats, oils, foods, petroleum products, and rubber.

A free radical is an atom or group of atoms containing at least one unpaired electron and existing for a brief period of time before reacting to produce a stable molecule.

Vitamin E is an antioxidant.

Antiperspirant is a substance applied to the skin to reduce sweating. They reduce the processes in sweat glands and/or block ducts that carry the sweat to the skin surface.

Antiplatelet drugs help prevent platelets sticking together to form blood clots. Usually they are taken regularly. Such drugs are also given after heart surgery to prevent clots forming. Aspirin is the most widely used antiplatelet drug. See International Normalized Ratio.

Antipyretic is a drug that reduces fever – eg paracetamol and under Analgesic, aspirin.

Aorta is the large artery that emerges from the heart’s left ventricle, and carries blood towards the rest of the body. Aortic is the adjective meaning ‘of the aorta’.

Aortic aneurysm is a sac and/or dilation at some place in the aorta where the aorta artery wall may be weakened or damaged.

Aortic coarctation is a congenital condition where the aorta is narrow, so the heart has to work harder to pump the blood through it and/or work at a higher heart rate. It causes breathlessness and continual tiredness. The treatment is usually an operation.

Coarctate (adjective) and coarctation (noun) have two meanings:

- enclosed in a hard barrel-shaped outer case, like a pupa of a housefly

- constricted, crowded or pushed together.

Aortic dissection means surgery on part of the aorta.

Aortic stenosis. Stenosis of the aorta. The narrowing of the aortic valve restricts blood flow, so the ventricle has to work harder to pump blood round the body. It can also damage the left ventricle, and may need surgery.

Aortic valve is the valve between the left ventricle and the aorta, which allows blood to flow out to the rest of the body but not backwards. See Valve.

AoYA see Age Of Your Arteries.

Apnoea is a temporary inability to breathe. Compare Dyspnoea (or dyspnea) means breathlessness. Exertional dyspnoea means breathlessness on exertion. Nocturnal dyspnoea means night breathlessness.

Apple a day. Flavonoids in the diet lower heart disease risk. Quercetin and epicatechin are the major flavonoids in our diet – their main sources being red wine, cocoa, onions, tea, (particularly) apples, and (to a lesser amount) cocoa – remember by ROTA Red wine, Onions, Tea, Apples or ACTOR.

There is increasing evidence that diets rich in fruits and vegetables are associated with a reduced risk of chronic disease such as cardiovascular disease. This may be due to the abundance of phytochemicals (plant chemicals) known as polyphenols that occur in these foods. The Institute of Food Research staff are researching protective effects of a particular class of polyphenols occurring naturally in apples against vascular disease.

Arachodonic acid is an omega-6 fatty acid, and is synthesized from linoleic acid. The human body can do that synthesis, but cats cannot! It forms the basis of some prostaglandins. The formula is C20H32O2 – it has a chain of 20 carbon atoms. See Arachodonic acid under Fatty acids.

Arrhythmia means an abnormal rhythm of the heart. This may be from a birth defect, coronary heart disease, other heart disorders, overactive thyroid gland, caffeine, and/or drugs for Parkinsonism or incontinence. See Atrial fibrillation, Supraventricular tachycardia and Arrhythmogenic right ventricular cardiomyopathy under Cardiomyopathy.

Artery. An artery is a blood vessel in which blood flows from the heart to part of the rest of the body. The main artery from the lower left ventricle of the heart is the aorta. The tubes from the lower right of the heart to the lungs are also called arteries. Compare vein. See coronary arteries, coronary artery bypass graft, Internal mammary artery.

The Artery risk factors that cause narrowing and/or blockage of the arteries are:


high blood pressure

high cholesterol

● being overweight

● lack of exercise

● history of heart disease in the family

● if you are male

● if you are diabetic

● if you suffer with stress.

These risk factors do not make it certain that a person will have heart trouble. Some people develop angina without having any of these risk factors.

Arthritis is an inflammation of joints, causing pain and stiffness. See Arthritis under NSAIDs.

Artificial pacemaker. An artificial pacemaker is an electronic device fitted under the chest skin, and that can generate a pulse to control heart rate. It is usually fitted to patients that have a slow heartbeat. Compare Implantable cardio-defibrillator.

Aspartate aminotransferaseAST, is an enzyme normally present in liver and heart cells.

AST is released into blood when the liver or heart is damaged. The AST levels in the blood are thus elevated when there is liver damage, eg by viral hepatitis or from a heart attackHepatitis is an inflammation of the liver, which can be caused by smoking, drugs, alcohol, chemicals, and autoimmune diseases.

Viral hepatitis means hepatitis caused by viruses that primarily attack the liver.

AST is also called serum glutamic oxaloacetic transaminase (SGOT).

Aspirin in low doses helps to prevent blood clots and to reduce the viscosity of a patient's blood, thus making it flow better, and thus reducing the need for higher blood pressure to pump it round the body – see Antiplatelet drug. This decreases the risk of a heart attack or stroke. It is important to take the correct dose, usually 75-150 mg daily, as higher doses will not have the desired effect on the blood or heart.

Take aspirin at bedtime rather than each morning This reduces the risk among patients who have had a heart condition significantly more than taking in the morning, a research trial has shown.

Aspirin is a non-steroidal anti-inflammatory drug (NSAID). Aspirin also reduces inflammation, and in the correct low dosage prevents abnormal blood clotting, but normal doses irritate the stomach lining. Soluble or dispersible aspirin in water is absorbed into the bloodstream faster than tablets would be, but still irritates the stomach lining.

Aspirin has been used as a pain reliever since about 1920, and is present in many medicines for colds, flu, headaches, and other pains. Aspirin tablets as such generally have higher doses, eg 300 mg.

Higher doses of aspirin than 75-150 mg may injure the stomach lining, and cause stomach ulcers* and intestinal bleeding. This has been known since the 1950s or perhaps earlier. Thus generally, people should not take aspirin as a pain reliever. Preferably take paracetamol or ibuprofen or whatever a doctor recommends. Aspirin can also trigger asthma attacks. As regards stomach ulcers, aspirin is an NSAID:

See under NSAID.

Aspirin as a drug. A daily low dose of 75-150 mg of aspirin, usually 75mg daily, is to reduce the stickiness of the patient's blood, thus decreasing the chance of a heart attack or stroke. Aspirin should be taken at the same time every day. Take aspirin with or immediately after food as this reduces the risk of stomach irritation. Most people take soluble or dispersible aspirin, which are white tablets that should be completely dispersed in a small glass of water. Research has shown that it is better to take the 75mg aspirin at night, to fit the circadian rhythm than to take it in the morning.

Aspirin side effects are rare, when the dose of aspirin is very low. Occasionally aspirin may cause stomach upsets or indigestion pain, but this should be prevented if the dose is taken with food or milk. If you, the patient, still suffer stomach pains then you should contact your doctor. Aspirin occasionally causes wheeziness due to an allergic reaction – if you experience this you should contact your doctor. See above for higher doses.

If you require medication as a painkiller, you should take one that does not contain any aspirin, such as codeine, paracetamol, or co-codamol which is a combination of codeine and paracetamol.

Many cold remedies may also contain aspirin as well as other ingredients and these remedies should be avoided to keep the aspirin dosage correct. Ask your pharmacist for advice if you are not sure. It is helpful to keep a list of all the medication you are currently taking and their dosages with you whenever you visit a doctor or hospital.

Aspirin & Reye's syndrome. Experts advise that one should never give aspirin to anyone under 16, because of the risk of a rare but sometimes-fatal liver and brain disorder called Reye's syndrome.

Assertion. Assertion has two meanings.

- In ordinary usage it refers to a positive statement – perhaps made without any evidence or justification.

- In science and medical research, an assertion is a proposition that may be true or false, and carefully worded so that its assumptions and meaning are clear. Usually the intention is to state exactly what is to be tested, eg a particular null hypothesis, as explained under Statistically significant.

AST See Angiotensin sensitivity test. Also Aspartate aminotransferase.

Atheroma is the term for the fatty material that builds up on the inside walls of arteries, particularly the coronary arteries. This usually leads to angina pain. Similar build-up in arteries supplying the brain may lead to a stroke.

Atherosclerosis means the fatty deposits on artery walls due to the build-up of cholesterol and other cells; with related thickening of the walls, so the narrowing reduces the blood flow.

The term also means the narrowing and thickening of the arteries. Where this occurs in coronary arteries, it reduces the blood and oxygen reaching the heart muscle, so less blood can be pumped around.

Atherosclerosis is the leading cause of cardiovascular disease (CVD) mortality, and is an inflammatory disease.

Atherothrombosis means plaque tearing. The fragments may lead to blood clots forming and thus the furring up or blocking of arteries.

Atom see atom under Organic chemistry. See also atomic number, atomic weight under Organic chemistry.

Atrial fibrillation is a very common abnormality of heart rhythm – about 10% of people over the age of 70 have it. When this occurs, the top chambers of the heart – the atria – beat in a chaotic fashion, called fibrillation. It may be treated with drugs and/or by ablation.

Paroxysmal atrial fibrillation comes and goes, and each episode usually stops within 48 hours to a week, maybe stopping without any treatment.

Persistent AF lasts more than a week - or less if treated.

Longstanding persistent AF lasts a year or more.

Permanent AF is present continuously.

See separate factsheet on Atrial Fibrillation. See also Paroxysmal atrial tachycardia.

Atrioventricular node, AV node. The AV node is the usual conduction pathway between the upper and lower chambers of the heart. It normally delays conduction by about 120ms, which ensures that the blood is pumped correctly into the ventricles before they contract.

Atrial septal defect. This is a hole between the two atria, sometimes called 'hole in the heart'. Thus oxygen-rich blood can flow from the left atrium to the right atrium and give increased blood flow to the lungs. This increased blood flow to the lungs causes a swishing sound. The effect of atrial septal defect is to reduce considerably and seriously the amount of oxygen in the blood flowing round the body, causing the skin to look pale blue, called cyanotic.

Atrium. The plural is atria. The right atrium RA is the upper right chamber of the heart, where blood from the body enters before flowing to the right ventricle. Similarly the left atrium LA is the upper left chamber, where oxygenated blood from the lungs enters and then flows to the left ventricle and thus to the rest of the body.

Automatic external defibrillator, AED. An AED is a machine that gives a controlled electric shock to restart the patient's heart. Ambulances carry an AED. Never give such an electric shock to a patient that has a pulse.

For a reasonable chance of survival this is needed within 8-10 minutes of a patient's collapse, hence the urgency to call 999.

The rule for an Automatic external defibrillator (for a lay person) is that it should only be attached to a patient who is both not responding and not breathing. Lay people should not check for a pulse – it will waste time and may be incorrect. Provided the patient is both unresponsive and not breathing, the AED can be relied upon to deliver a shock only if necessary.

See also ambulance.

Public Access Defibrillators (PAD) are available eg in shopping centres, entertainment venues, and other public places. Once opened, the machine gives instructions through its computer and loudspeaker.

Automatic implantable cardioverter defibrillator, AICD. An AICD is a device implanted to monitor the heart and that will if needed automatically deliver a controlled electric shock to restart the heart.

Average. The word 'average' means whichever is appropriate of three different calculations on a set of values. Usually the average is taken to be the mean unless the context implies otherwise.

The mean is the total divided by how many. Eg the set of five values 7, 7, 12, 12, 12 has mean 10 = (7+7+12+12+12)/5. Also see Standard deviation.

The mode is the value that occurs most. Eg the mode of 1, 1, 2, 14, and 15 is 1. This is useful where some consequence depends on the commonest case.

The median is the central value of an odd number of values, or is the mean of the central two if there are an even number. Eg the median of 1, 3, 5, 16, and 17 is 5; and of 1, 4, 5, 6, and 17 is also 5. Essentially, half the values are above it, and half are below it.

AVPU see consciousness.

AVR = Aortic valve replacement. See Valve surgery.


This information was created and edited by Richard Maddison for the BCPA.
Copyright © 1997-2019 The British Cardiac Patients Association, and/or Richard Maddison.
BCPA Head Office: 15 Abbey Road, Bingham, Nottingham NG13 8EE
Reg Charity 289190. Email:

First published in this form 2002, and updated 2005, 2007, 2008, 2011, 2012, 2013, 2017.
All rights reserved. No part of this work may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, without written permission from the BCPA Head Office.

We give permission for copies to be stored and made within the BCPA and any UK hospital; and these hospitals may give printed but not electronic copies to patients provided the source and copyright is acknowledged on the copies - eg include the page footer.

Authors, sources and acknowledgements

The main sources are BCPA Journal published articles, other information from authors, and publicly available documents and websites. In many cases the journal articles give sources and further information than the Glossary entries.

Parts of the wordings under ECG and Echocardiogram are adapted with permission from BUPA's health information resources, available at

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Richard Maddison

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