Glossary Of Terms - C

Calcium channel blockers Calorie Campylobacter Cannula Capillaries Carbohydrates
Cardiac Cardiac arrest Cardiac ultrasound under echo Cardiology Cardiomyopathy CPR Cardio-pulmonary resuscitation
Cardiovascular Cardiovascular Patients Bill of Rights DC cardioversion Carotid artery Catheter Cheeses – Fat content*
Chelating agent Chest pain other causes Cholesterol HDL LDL Chronic heart failure CHF
Chronic pain under Pain Circadian rhythm Cis fatty acid Clostridium difficile C Diff Clot Co-
Collapse blackout syncope fall Consent Coronary artery bypass graft CABG Corticosteroids Creatine Cyanocobalamin
cyclo-oxygenase = COX, under NSAID

CABG stands for Coronary artery bypass graft. Pronounced 'cabbage'.

Calcium channel blockers are drugs used to relieve angina, reduce high blood pressure, and/or slow the heart rate. They act on the muscles of the walls of arteries to prevent narrowing. See Antihypertensive. They are prescribed for various conditions.

● Relieve angina

● Reduce high blood pressure

● Slow the heart rate.

Several calcium channel blockers are available. These differ in their possible sites of action and their side effects. It is very important never to stop taking a calcium channel blocker without consulting your doctor.

Amlodipine - Brand name Istin
Diltiazem - Brand names Adizem, Tildiem
Felodipine - Brand names Cardioplen, Felotens, Keloc, Neloc, Plendil, Vascalpha
Nicardipine - Brand name Cardene
Nifedipine - Brand names Adalat, Coracten, Nifensar
Verapamil - Brand names Cordilox, Securon, Univer


Side effects of Calcium Channel Blockers. Occasionally people suffer with headaches and facial flushing, which usually stops after a few days as the body adjusts to the medicine. Those taking Verapamil may suffer constipation. Calcium Channel Blockers may cause dizziness. Again this should pass as your body adjusts to them. If you notice any side effects, you should contact your doctor, so that he or she may change your medication if these side effects become intolerable.

Calibre. The calibre of an artery is its internal diameter. Where there is plaque the partial blockage effectively reduces the calibre.

Calorie. A calorie is a unit of quantity of heat or energy. For measuring the amount of energy in foods, people use kilocalories, kcal, which is 1000 calories, which should be written Calories with a capital C to indicate kilocalories. People typically need 1800 to 2500 kcal per day. They use about 75 to 80 kcal per hour when resting in bed; and 80 to 90 when sitting and not doing any significant physical activity. During exercise the rate may double.

A Joule is a measure of heat or energy, being one Watt for one second. The conversion is 4.2 Joules per calorie, or 4.2 kJ per kcal. A slice of bread gives about 300 to 350 kJ, ie 70 to 80 kcal.

Campylobacter is the UK's commonest form of food poisoning – 42,226 cases and about 70 deaths in 2006. The true number of cases may be higher as many people might not go to see their GP. In vulnerable groups it may cause other complications. Some chicken flocks are carriers, leading to food poisoning.

Cannula A cannula is a small tube that can be inserted into a vein or artery with a tap and connections. It can be connected to the supply of a drip or required fluid, to administer appropriate injections, or to drain off fluid. This avoids needing a fresh needle being inserted for each different injection that a patient may need over some time.

Capillaries are the tiniest thin-walled blood vessels that arteries divide into, and where oxygen and other nutrients in the blood pass to muscles and other tissues.

Carbohydrates are an important source of energy as food. They are organic compounds containing carbon, hydrogen, and oxygen, usually with the hydrogen and oxygen in about the same ratio as in water. They include sugars – such as sucrose; and polysaccharides – such as cellulose, glycogen, starch, and various forms of glucose including dextrose. See also under Sugar, Diet, and Glycaemic Index.

Carboxyl COOH see carboxyl under Organic chemistry.

Carcinoma. A carcinoma is a malignant tumour, or another name for a malignant cancer.

Cardiac means relating to the heart. A cardiac patient has a heart disorder; and a cardiac drug is one that stimulates heart muscles.

Cardiac arrest means the heart has suddenly stopped beating. Cardiopulmonary arrest means the same.

There is no pulse or breathing. The commonest cause is a chaotic electrical pattern caused by a ventricle or heart muscles being damaged or starved of oxygen. Causes include heart attack, severe blood loss, suffocation, electric shock, anaphylactic shock, drug overdose, and hypothermia.

Treatment: See ambulance for when to call an ambulance. CPR and resuscitation, defibrillation.

Cardiac catheterisation is a procedure where a catheter is passed along arteries to reach a particular coronary artery, and an X-ray video is recorded while a harmless dye is injected, causing the blood flow during each heartbeat to show on the X-ray. This helps detailed diagnosis, pinpointing the sites of blockages, and assessing the seriousness.

Cardiac ultrasound See Echocardiogram.

Cardio- means of the heart. See also cardiovascular means of the heart or blood vessels.

Cardio and Vascular Coalition was a group of 41 charities and professional organisations with an interest in heart disease, stroke, kidney disease, and diabetes; and on which Sir Terence English represented the BCPA.

The document launched on 25 March 2009 addressed key areas of need – including preventative measures, congenital conditions, acute and chronic cardiovascular disease, rehabilitation, and end of life care. It was intended to influence departmental policies and strategy for the next decade and hopefully would achieve this. The 24 A4 pages report is at (This is not a link). Part is copied below.

'In 2013 The Cardio and Vascular Coalition (CVC) is a national coalition of 36 voluntary and professional organisations with an interest in promoting and protecting cardiac and vascular health in England. The interests of the CVC membership cover cardiac and vascular and related conditions - heart disease, diabetes, stroke and kidney disease - from pre-birth to end of life care. Excellent progress has been made tackling cardiovascular diseases over the last decade. But we cannot be complacent. The fact that we're living longer and our lifestyles are unhealthier means more needs to be done to sustain and improve progress. The Government’s announcement that it would be producing a new Cardiovascular Disease Outcomes Strategy in the winter of 2012/13 recognised this and was welcome acknowledgement of the links between the various conditions. All Party Parliamentary Groups (APPGs) on Heart Disease, Stroke, Kidney and Diabetes joined forces to produce a report examining what the priorities for the strategy should be. The APPGs' report has been informed by submissions from the Cardio and Vascular Coalition. The report calls for:
- Ensuring local authorities offer health checks to those at high risk as a priority, and report what action is then taken
- Investment in public health campaigns and consideration of further public health regulation
- Clinical networks to be given a key role in implementing the strategy
- Publishing an Atlas of Variation of care in England that the NHS Commissioning Board should use to ensure consistent standards
- Making sure all health professionals have the knowledge and training needed to support people living with cardiovascular diseases
- Recognising the strategy should be a cross-government responsibility.'

Cardiology is the branch of medicine of the heart and its diseases.

Cardiomegaly. Cardiomegaly showing on chest radiography means an enlarged heart. See heart failure diagnosis.

Cardiomyopathy has two related meanings.

Firstly, it means the cause of the patient’s heart damage, which sometimes is initially not clear.

Secondly, cardiomyopathy is a heart-muscle disease that makes heart muscle flabby and weak. The heart then becomes bigger as the heart muscle wall expands under the strain. The cause is not understood.

Dilated cardiomyopathy means the heart is enlarged – and pumps less strongly. This means enlarged chambers.

Hypertrophic cardiomyopathy is heart muscle being thicker than normal. In some patients the muscle becomes thicker and can partially block the flow of blood out of the left ventricle to the rest of the body.

Restrictive cardiomyopathy is a heart-muscle disorder where the walls of the ventricles become stiff, but not necessarily thickened, so they resist normal filling with blood. The heart muscle is stiff and doesn’t relax properly.

Arrhythmogenic right ventricular cardiomyopathy is an inherited heart-muscle disorder where damaged heart muscle is gradually replaced by scar tissue and fat.

Cardiomyopathy Association, CMA. The Cardiomyopathy Association, Registered Charity 803262, helps people and their families affected by the heart muscle condition cardiomyopathy.

The CMA provide support and easy-to-understand information on the different types of cardiomyopathy. The Cardiomyopathy Association meets a need unfulfilled by any other organisation and is supported solely by public donation.

As well as information on their website (This is not a link), they provide booklets on the three main types of cardiomyopathy – hypertrophic cardiomyopathy, dilated cardiomyopathy, and arrhythmogenic right ventricular cardiomyopathy. They also have videos and CD ROMs on hypertrophic and dilated cardiomyopathy. They have support groups around the UK where members can learn more about the condition and share experiences. They have a network of people affected by the condition who can offer one-to-one support on the telephone. They hold regional information days around the country at which cardiologists experienced in dealing with cardiomyopathy give presentations on the condition, latest treatments and research, and answer members' questions.

The CMA has a long-established link with the Specialist Inherited Cardiovascular Disease Clinic run by Professor William J McKenna, a world expert in cardiomyopathy, at the Heart Hospital, London.

The association's work is recognised and supported by The BCPA, The British Heart Foundation, and The British Cardiac Society. Their freephone helpline is 0800 018 1024, 8.30am to 4.30pm on weekdays.

Cardio-pulmonary resuscitation CPR is a first aid technique using chest compression and artificial ventilation, used till an ambulance arrives. It gives some oxygen supply and is the best that can be done. Unfortunately CPR alone may not always start the heart beating again properly. CPR is unlikely to bring a casualty back to life, but can prevent damage to vital organs, thereby giving the casualty a fighting chance of eventual full recovery by the treatment the emergency services will give.

Some people have extended the meaning to include defibrillation with an automatic external defibrillator.

The procedure is to do chest compressions at the rate of 100 compressions per minute. For many years the procedure was to do 30 compressions then two breaths and repeat, but that is now obsolete.

Cardiopulmonary arrest means the same as cardiac arrest, though the term implies breathing has stopped. In practice, if the heart is not beating the patient will also not be breathing.

Cardiovascular means relating to the heart and its associated blood vessels, and the circulation of blood.

Cardiovascular disease, CVD includes coronary heart disease, stroke, and peripheral vascular conditions. There can be a narrowing of arteries both in the heart and throughout the body from a build-up of fatty acids that form plaques - ie atherosclerosis.

Cardiovascular Patients Bill of Rights. Launched on 14 January 2008, this is a call to action developed by the BCPA, to set out what we believe cardiovascular patients should be entitled to during their NHS care.

It echoes some of the more general rights laid out in the Government’s NHS Constitution, but goes further calling for improvements in services throughout the patient journey; from emergency admission right through to rehabilitation and wellbeing.

We set out five key pledges that we wanted the NHS to implement. These are:

- The right to effective primary care management – green light not blue light

- The right to early intervention – acting fast, to make the most difference

- The right to the best treatment – effective therapy for all

- The right to joined-up support and care – care designed around the patient, not the organisation

- The right to holistic risk assessment – treat the patient, not just their symptoms.

Cardioversion. See DC cardioversion.

Care and Quality Commission CQC From 1 April 2009 the new Care & Quality Commission took over the work of the Healthcare Commission, the Commission for Social Care Inspection, and the Mental Health Act Commission.

The Care and Quality Commission regulates and improves the quality of health and social care and looks after the interests of people detained under the Mental Health Act. The work, bringing together regulation of the quality of health and adult social care for the first time, will touch the lives of almost everyone in England. (This is not a link). See balanced scorecard.

Carotid artery These are the two arteries that are one each side of the front of the neck. The pulse can easily be felt there. These arteries carry blood to the brain and all parts of the head and face.

Catalyst. A catalyst speeds up a chemical process, but usually does not itself get used up or changed chemically. Vitamin B6 is a catalyst for various body metabolism processes.

Catheter means a tube that is inserted into an artery and passes along the artery to the heart. See Angioplasty catheter, Valvuloplasty.

Cerebrovascular means of or relating to the blood vessels of the brain and the blood supply to the brain. Cerebrovascular disease means disease of these, eg stroke.

Cerebrospinal fluid. See cerebrospinal fluid under meningitis.

CHD stands for(to the public) Coronary heart disease or (to medics) Congenital heart disease.

Cheese – See factsheet on Fat content of cheeses.

Chelating agent means a chemical used to treat a poison – eg metals such as arsenic, iron, lead, and mercury. Chelation works by converting the poison to something less harmful, and/or causing the body to get rid of the original eg in urine. Penicillamine is a chelating agent.

Chelation therapy means treating and caring for a patient with some metal or other poisonous substance as above.

Chemistry Some chemistry terms are explained under Organic chemistry.

The chemical name for a drug essentially describes its chemical composition and is normally not used by medics, pharmacists or patients. Chemical names are used by research chemists, and in schools and universities.

Chemotherapy is drug treatment of cancer.

Chest pain – causes other than heart attack It may be helpful to be able to distinguish the following different causes of chest pain, some of which are not heart related.

The bullet and italics below are symptoms or a possible question a first aider or carer might ask.

Does your chest hurt when you physically exert yourself, and/or do you feel tightness in your chest, and/or does the pain sometimes also seem to be in your left arm, left shoulder or neck?

If so, this may be a heart-related issue. If such a pain starts suddenly and is severe this may be a heart attack, so send for an ambulance and do as above.

If the pattern has occurred several times, but perhaps mildly so there seemed no need for any treatment, contact your doctor – it may be angina from not enough blood reaching the heart muscles.

Does your chest hurt when you move, cough and/or sneeze?

If so, the cause may come from the chest muscles, bones, or joints, or from an injury. Preferably avoid strenuous activity and take an anti-inflammatory pain reliever such as ibuprofen or paracetamol.

Do you feel that your chest pain constricts your chest, and/or is the pain below the left breast?

If so, this may be due to anxiety or stress. So try to relax, take deep breaths, and try to do something about the reason for the stress.

Does your chest hurt when you have food and/or hot drink, alcohol, and/or when lying down?

If so, this may be heartburn, which nothing to do with the heart.

Do you have any red spots, rash, or blistering on your chest?

If so, this may be shingles, a disease affecting the tissues between the ribs, and caused by a reactivation of chickenpox. See your doctor, and if it is shingles, since anyone who has not had chickenpox could catch it from your shingles, please avoid contact with pregnant women.

Also, it may be meningitis – (test by pressing with a glass tumbler and if the red spots do not disappear when pressed on it is likely to be meningitis and hospital treatment is urgently needed), or Weil's disease if they have been near a river, lake, seaside, or sewage works.

Is the pain worse when you take a deep breath?

If so, this may be an inflammation of the pleura, which are the membranes that cover the lungs and linings of the chest cavity. It may be caused by a chest infection. Various causes have similar symptoms, so see a doctor.

Cholesterol is a white or pale yellow almost insoluble waxy chemical in animal tissue, blood, bile, and animal fats. It is naturally occurring in the body and needed for normal growth and health. The level of cholesterol can be measured in a blood test.

Cholesterol is the single greatest risk factor for the nation’s biggest killer – coronary heart disease. Cholesterol is also a significant risk factor for cardiovascular disease, which includes coronary heart disease, stroke, and peripheral vascular conditions.

Cholesterol is produced by the body as well as absorbed from food and it is an essential component in every cell in our bodies. Cholesterol is only a problem if we have too much of it. Unfortunately, almost every one of us does – and many of us dangerously so. The real tragedy is that most people could avoid unhealthy levels of cholesterol because the most common cause of high cholesterol is excess saturated fat in the diet.

Too high cholesterol increases the likelihood of depositing it on the inside walls of blood vessels, leading to narrowing or blocking of them. This increases the risks of heart attacks, stroke, and/or other cardiovascular disease. If it is too high the patient will be advised to cut down on fats generally and especially saturated fats – found in dairy products and fatty meats; and where appropriate stop smoking, and/or lose weight. See Fats.

A blood sample, taken after a person has fasted for several hours, can be used to measure the levels of all forms of cholesterol. In the UK, the average total cholesterol level is 5.7mmol/l, which is regarded as too high.

For details of high cholesterol terms and values see under Hypercholesterolaemia.

Cholesterol HDL and LDL

The components of cholesterol are high-density lipoprotein, HDL; and low-density lipoprotein, LDL.

HDL is good and should be at least a fifth* of the total: it is vital in protecting against coronary heart disease.

But too high LDL is believed to be bad and makes the risk of coronary heart disease higher.

In the years 2003-5 the recommendations changed slightly. After 2005 (still the same in 2008), various cardiologists and doctors recommend whichever is appropriate of the following criteria.

● The total HDL plus LDL should be less than 5.0.

● The total should be less than 4.8, or preferably even less particularly for patients who have had serious heart conditions and are thus at increased risk.

● The thing that matters is the LDL more than the total, and the LDL should be less than or equal to 3.0 to 4.0 for those at increased CHD risk. Some medics are now (2012) recommending LDL less than or equal to 2.0.

● The ratio of HDL to the total should be at least one fifth; but some experts say at least a quarter, which had been the previous recommendation for many years.

See also Statin. Statins work by reducing cholesterol production by blocking an enzyme found in the liver. Thus they slow the progression of heart disease.

Cholesterol UK is a joint initiative of H·E·A·R·T UK and the British Cardiac Patients Association (BCPA). The charities came together in 2002 to address a mutual concern at the low level of cholesterol awareness among the British population, the lack of focus on primary prevention, and the implications of high cholesterol levels as a serious risk factor for cardiovascular disease.

Cholesterol UK aims to improve public understanding of cholesterol through education to raise awareness of how diet and lifestyle change can significantly reduce cholesterol levels. Cholesterol UK is lobbying government and related organisations, such as the Department of Health and the Food Standards Agency (FSA), for a national awareness campaign on fat and cholesterol and for greater access to high quality cardiovascular risk testing, which includes cholesterol testing, to enable better understanding of personal risk factors.

Cholesterol UK was (2007) supported by ALPRO Ltd, Merck Sharp & Dohme Ltd and Schering Plough Ltd (joint partners), and Unilever Ltd. Cholesterol UK believes it is important to work in partnership with a broad representation of organisations to help achieve its objectives and seeks to encourage new Cholesterol UK partners.

Chronic heart failure, CHF. Chronic means continuing for a long time and/or continually recurring. For chronic heart failure, CHF see under heart failure terms.

Chronic total occlusion, CTO. Chronic means continuing for a long time and/or continually recurring. Occlusion means being blocked. So CTO means a total blockage that lasts a long time or occurs again after it has been cleared.

Circadian rhythm. The normal body temperature varies slightly each 24 hours, rising in the evening and having a minimum about 5am – called circadian rhythm. About six hours or more after getting up, ie in the early to mid afternoon, a second slight lowering and minimum occurs, but the temperature does not go as low as at 5am.

The heart rate ie pulse rate, the breathing, and the general level of activity and alertness also vary similarly – being slightly lower at the times that the temperature is lower. Here we are ignoring the effects of deliberate activity, stress, illness, or rest.

The circadian rhythm is reset to keep in phase with each day by the light of morning and getting up. The rhythm is controlled by the production of the hormone melatonin – normally slightly more is produced in the evening and slightly less at the low times. The bright light of morning reduces the amount of melatonin produced then and thus resets the rhythm.

So if you have to get up in the night, eg to go to the toilet, preferably don’t put a light on, as the light reaching your eyes may upset or reset your circadian rhythm. Also, when getting up from lying down, sit up and then stand up slowly, to give time for your body’s systems to adjust the heart and blood pressure to avoid you risking fainting or a syncope from slight shortage of blood pumped upwards to the brain.

Some people have done experiments in which a subject person stayed in a place that had no information about the real time of day, and generally they gradually settled into a longer circadian rhythm – typically up to 28 hours instead of 24 per cycle of sleep, meals and activities.

The body temperature and level of activity is also related to the level of thyroxine, which is produced by the thyroid gland. Thyroxine can also be prescribed. See also the related research under double-blind trial, and basal metabolic rate under metabolism.

Because of the way the circadian rhythm works, people should not do physical exercises immediately before going to sleep, as this may tend to trigger increased temperature, heart rate, breathing and brain activity, and keep them awake.

Cis. See cis under Fatty acids.

Clavicle. A clavicle is a bone that connects the shoulder blades with the upper part of the sternum / breastbone. There is one each side.

Clopidogrel is an antiplatelet drug used to prevent blood clots from forming. So it is taken:

● to stop blood cells sticking together in your arteries, ie prevent blood clots forming, thus decreasing the chance of a heart attack or stroke

● as it may be suitable for patients who cannot take aspirin for its antiplatelet effects. It reduces the tendency of platelets to stick together when blood flow is disrupted. It can lead to abnormal bleeding.

● by some patients who have had a stent inserted into a coronary artery. For such patients it is usually given only for a short period – usually four weeks.

● by some patients with acute coronary syndrome or unstable angina, and then taken for up to a year. Such patients probably need to continue taking aspirin as well whilst on Clopidogrel. It increases the effect of the aspirin.

● by some patients who have a true allergy to aspirin, and therefore Clopidogrel may be given as an alternative.

Clopidogrel is typically prescribed to patients who have had a tendency for clots forming in the coronary arteries, or have or have had any of:

● a stroke

● a heart attack

● angina, particularly unstable angina.

The brand name is Plavix.

Clopidogrel is similar to aspirin, but works differently, and is only used for certain groups of patients. It is prescribed to patients who have a tendency to form clots in the fast-flowing blood of the coronary arteries, and/or who have had a stroke or a heart attack.

It is taken as tablets, 75mg once a day. It may be taken with water and either with or without food. The effects start after an hour and last 24 hours. If you miss a dose, take it as soon as you remember. If in doubt, contact you pharmacist or doctor for advice. Never double your dose or take extra. If by error you take too many contact your doctor or local hospital. The tablets should be kept in a closed container in a cool, dry place out of the reach of children.

Long-term clopidogrel
Certain patients at risk of recurrent myocardial infarction MI and treated with clopidogrel may be on the drug longer than necessary and get internal bleeding, researchers believe.
Dr Rikke Sørensen, at Copenhagen University Hospital, Gentofte, studied the records of 12,000 patients who had been:
- admitted to hospital with myocardial infarction (destruction of an area of heart muscle from obstruction of a coronary artery); and
- treated with percutaneous coronary intervention; and
- given clopidogrel.
The records gave how long afterwards they were still on clopidogrel – eg 6+ or 12+ months.
Bleeding occurred in 3.5% of patients in the six-month regimen and in 4.1% in the 12-month regimen. So adopting a shorter time period could be beneficial in reducing the occurrence of bleeding.
Both groups had similar rates of death and of recurrent MI. So the potential benefit of the longer clopidogrel treatment remains uncertain.
NICE currently recommends that patients are treated with clopidogrel in combination with low-dose aspirin for up to 12 months after the most recent episode of non-ST-segment-elevation acute coronary syndrome.

Side effects of clopidogrel are relatively rare, but some people may experience:

● bleeding and bruising, which are the main adverse effects of Clopidogrel. These may include nosebleeds, bleeding from a stomach ulcer, or blood in the urine. If you get these contact your doctor without delay.

● abdominal pain, nausea, and/or vomiting. If you experience these you should take your tablet with or after food.

● skin rash or itching, in which case contact your doctor but it is not urgent

● a sore throat, in which case stop taking the drug and contact your doctor immediately.

Clopidogrel interacts with aspirin, increasing the effect of the aspirin on platelets, and possibly increasing the risk of gastrointestinal bleeding. It also increases the coagulant effect of warfarin when both are taken. Maybe take the aspirin at bedtime and the clopidogrel in the morning.

Clostridium difficile. In 2006 there were 55,681 reported cases of patients over 65 with Clostridium difficile, C diff – up 8% on 2005, and taking 23,346,850 bed-days. In 2005 there were 51,767 cases; and in 2004 44,314 cases.

In England & Wales in 2005, 3807 death certificates mentioned Clostridium difficile.

C diff infection is the most important cause of hospital-acquired diarrhoea. It is a bacterium (bug) found naturally in the gut of 3% of healthy adults and 66% of infants, and people may have it harmlessly on their skin. It rarely causes problems in children or healthy adults – as other normal 'good' bacteria in the intestine keep it in check.

Unfortunately some antibiotics kill these 'good' bacteria, making C diff more likely. C diff disease occurs when certain broad antibiotics (given to treat MRSA) disturb the normal healthy intestinal bacteria. This allows C diff to flourish, producing a toxin that causes diarrhoea.

The C diff diarrhoea may be a mild disturbance for a few days or a very severe illness with bleeding from the colon (colitis), and perforation of the intestine leading to peritonitis, which can be fatal. The treatment is usually to stop the broad antibiotic and/or change to a different antibiotic. 

Hand washing and room cleaning help prevent spread of C diff. Wash hands and arms up to the elbows for at least 30 seconds.

Hospital alcohol gel for rubbing on hands does not prevent C diff.

Clotting factors are chemicals in the blood that help to stop bleeding from a cut or injury. A clot is a lump of blood stuck together – eg to seal a small wound in the skin. It can also cause a blockage or partial narrowing of an artery or vein. See Anticoagulant.

Co-. Pain-relief products named 'Co-' – eg Co-codamol, Co-codaprin, Co-proxamol – 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 under aspirin.

Co-codamol is a generic product containing codeine and paracetamol. See also under aspirin.

Co-codaprin is a generic product containing aspirin and codeine.

Coarctate (adjective) coarctation (noun). See under Aortic coarctation.

Codeine is an opioid analgesic. Used as a cough suppressant and/or antidiarrhoea. See also under aspirin.

Collagen is a fibrous scleroprotein that is rich in glycine and praline and that yields gelatin on boiling, and with two meanings.

1 Natural connective tissues and/or bones.

2 An artificial manufactured similar material eg for the stem of an Angio-Seal®.

Collapse, blackout, syncope, and fall

A collapse informally is when a person suddenly falls down; or needs to sit, rest, lie down, or take it easy.

A Loss of Consciousness, LOC, is when a person suddenly stops being alert and aware of their body and environment – but not asleep. Transient and temporary both mean for a short time.

A Transient Loss of Consciousness T-LOC is when a person suddenly for a short time abnormally stops being alert and aware of their body and environment. This is informally called a blackout. Over half of blackouts are what medics call a syncope (pronounced like sin-co-pay).

A syncope is a transient loss of consciousness without damage to the brain or the nervous system, usually leading to collapse. The rapid onset is followed by complete spontaneous recovery. There is no damage to any part of the person’s body. The underlying mechanism is too little blood over the whole brain, lasting a very short time (transient global cerebral hypoperfusion). This causes lack of oxygen to the brain (cerebral hypoxia).

A syncope is often related to both brain and a heart or blood circulation condition, as * vasovagal fainting below.

In a person who may have fainted, the too-little oxygen will persist if he/she remains upright, and the lack of oxygen in the blood from not breathing will worsen the situation.

Amnesia means a partial or total loss of memory – eg a patient may have no memory of a collapse or how they came to fall.

A fall is unintentionally coming to rest on the ground or some lower level, but NOT as a consequence of: violence or injury, loss of consciousness, stroke, or seizure.

Heart, circulation, blackouts, syncopes, & fainting

60% of blackouts are syncopes triggered by heart and circulation, as below.

Our bodies have a system of nerves that connect the brain to the throat, voicebox, windpipe, ears, lungs, heart, and digestive system (called the vagus nerve or cranial nerve 10, being the tenth of 12). The nerves also bring back to the brain information from the senses – sensory information, hearing & touch.

When someone has a surprise or emotional shock, or gets too hot, the brain may send out signals through those nerves to tell the arteries and veins to dilate (get wider) to help blood flow. The signals may also slow down the heart.

Each carotid artery at the front of the neck (one each side) has a pressure monitor (the baroreceptor cells) that detects any drop in blood pressure, eg when suddenly changing from lying or sitting to standing. The brain quickly puts matters right, increasing the heart rate and/or blood pressure, so the person quickly recovers.

* Occasionally, the heart doesn’t pump quite enough blood against gravity to the brain. This can cause temporary fainting – vasovagal fainting. That vasovagal fainting is benign (= not life-threatening or health-threatening). It is a syncope related to both brain and a heart condition affecting blood circulation.

A tilt test can confirm the diagnosis by making it happen again under safe and recorded conditions.

Someone may alternatively have a temporary heartbeat stop (cardioinhibitory syncope or neurocardiogenic syncope). The heartrate suddenly increases, then decreases to below 40 beats/min, and stops for three seconds or more. The BP drops too low when or after the heartrate decreases, causing the syncope.

People can also faint from situations such as choking on food, vomiting, coughing.

Collateral has several meanings, including the following.

1 a person, animal or plant descended from a common ancestor but through a different line.

2 side by side.

3 supporting and/or corroborating.

By extension, where a coronary artery has a blockage, the branching smaller coronary arteries further on would not normally get any blood flow. But if one or more of these smaller ones join to other small arteries that are normally reached through a different coronary artery, they may get blood from there. This is collateral flow. Some of the branching smaller arteries will have blood flowing in the opposite direction to normal.

Coma is an unconscious state where the casualty does not respond to external stimuli such as noise or pain. See levels of consciousness.

Community Responders are trained people who live for example in a village that is a long way from an ambulance station, so an ambulance would take some time to get there. The Community Responders are therefore called by the emergency control to ask them to go immediately to the incident or place where the ambulance is needed. See also Community responders under Ambulance – when to call.

Compound See compound under organic chemistry.

Compression stockings fit tightly to help keep the blood circulation in the legs normal and to help prevent clots and/or an embolus.

Confidence interval Suppose someone wanted to know the average (mean) height of all men in the UK aged between 30 and 50. It’s not possible to measure everyone. So they would measure a sample and calculate the mean and standard deviation of the sample. They can also calculate an estimate of the corresponding figures for the whole population. They then say that with 95% confidence the true mean of the population is between some value and some other value – the confidence interval.

See also Hazard ratio, risk.

Congenital means a non-hereditary condition existing at birth, usually an abnormality. A congenital heart defect is an abnormality of a heart chamber or valve, which may increase the risk of heart failure; or a hole between two chambers. Both types can occur together. See Septal.

Most people with congenital heart disease lead full and active lives, but may need regular or occasional hospital checkups. Patients with more complex congenital heart conditions need regular and specialist care both at their local hospital and at a specialist centre.

Consciousness. There are four levels of consciousness. A casualty may be any of AVPU.

- alert eg can talk but maybe drowsy

- responding to voice, simple commands or questions

- responsive to pain, eg react by making a noise if you pinch the back of their hand – always say what you are doing

- unresponsive, no response at all. Coma means an unconscious state where the casualty does not respond to noise or pain. See response under first aid.

See ambulance for when to call an ambulance.

Consent. See separate factsheet on Consent. This includes living wills. See also Refusal, Do not resuscitate.

The general legal and ethical principle is that valid consent must 'usually' be obtained before starting treatment or physical investigation or providing personal care for a patient. This principle reflects the right of a patient to determine what happens to his or her own body and is a fundamental part of good medical practice. Case law has established that touching a patient without valid consent may constitute a civil or criminal offence. Poor handling of the consent process may lead to complaints from a patient.

My use of 'usually' above means there are exceptions. These include grounds of necessity, where the patient is unconscious or cannot communicate, and others.

Contraindication means something in a patient's current condition and/or medical history and/or genetics that increases the risk of an adverse effect of a particular drug.

Contralateral means opposite side. Lateral means side, eg one side of the body. Contra means against, opposing, opposite.

Control group means a group of patients used as a control in a statistical research experiment or trial eg of a drug or new treatment. They do not receive anything useful but are needed for comparisons. Usually in the trial they receive either a placebo or the standard quantity of an existing standard drug. So the effects of the new alternative drug or treatment on another group of patients can be determined from the comparisons and differences between the observed results of the other group and of the control group. See Double-blind trial.

Co-proxamol is a generic name for a drug containing paracetamol and an opioid analgesic dextropropoxyphene. It was withdrawn gradually starting January 2005. See co- under Analgesic.

Coronary means the blood vessels, nerves and ligaments surrounding a heart.

It is also used in the sense of a person having a coronary – short for a coronary thrombosis, essentially meaning the same as having a heart attack.

The terms coronary, coronary thrombosis, infarct, and myocardial infarction, MI, mean the same thing as heart attack. A thrombus is a blood clot mainly made up of platelets.

Coronary angiography. This is a procedure for helping diagnosis of possible blockages in coronary arteries or in veins or arteries of a past bypass.

See separate factsheet on Coronary Angiography and Angioplasty.

Under local anaesthetic, a fine tube is passed into a femoral artery in the groin and 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, indicating any narrowing.

Since about 2008 this can be done in a single day – so the patient is a day patient and normally is able to return home perhaps a couple of hours after the operation for recuperation and treatment in the hospital cardiac day ward.

Coronary angioplasty and stent insertion involves inflating a balloon inside the narrowed section of a coronary artery or a bypass graft to enlarge or open it to improve the blood flow to the heart muscle. Usually also, a stent is inserted to keep the artery or bypass open.

If you, the patient, have a blocked or narrowed coronary artery, or have had previous bypass graft surgery and your graft has become narrowed, it may thus be possible to correct the problem without major heart surgery. The success rate is now very high - eg 99% survival.

See separate factsheet on Coronary Angiography and Angioplasty.

Coronary arteries are the system of arteries and their branches that supply the heart muscles. The blood flow to these comes off the aorta and divides into three main arteries.

left anterior descending LAD at front left

right coronary artery RCA

left circumflex LCX at the back left.

Each of these then subdivides through branches to capillaries to feed blood to the heart muscle. See also under Heart.

For coronary artery disease see Coronary heart disease, artery risk factors and artery.

Coronary artery bypass graft, CABG, pronounced 'cabbage', is an operation that connects and replumbs coronary arteries to bypass their blocked part or parts. It uses an artery and/or vein from elsewhere in the patient’s body, such as a mammary artery and/or a leg vein.

See separate factsheet on CABG.

Coronary heart disease, CHD, means any combination of disorders of the heart or heart muscles or blood flows.

Coronary heart disease is also known as coronary artery disease, and ischaemic heart disease.

Coronary heart disease is narrowing (stenosis) of the coronary arteries by atherosclerosis – fatty deposits of plaque. This causes too little supply of oxygen to the heart muscles and tissues. Symptoms of the narrowing do not generally appear until the blood flow to some part of the heart is significantly reduced by the narrowing of the arteries. CHD may affect one or more arteries, which may be of different diameters (calibre). Each narrowing of an artery may be partial or total.

The narrowing may have no symptoms; or may lead to angina – chest pain that may be severe enough to restrict or prevent exertion. A critical reduction of the blood supply to the heart may result in myocardial infarction or death.

CHD is a major cause of disability and premature death in the UK.

Factors increasing the risks of CHD include:

- lack of exercise – 37% of CHD deaths are related to inactivity

- smoking – 19% of CHD deaths are related to smoking

- unsatisfactory diet, eg:

- not enough oily fish, poultry or meat, green vegetables and fruit

- too much salt, saturated fats, and/or excess alcohol

- increased weight or obesity – see BMI

- too high cholesterol LDL

- hypertension ie high blood pressure

- diabetes

- stress.

Of avoidable risk factors and lifestyle issues, the most important are lack of regular exercise, and smoking. Others include unsatisfactory diet, excess alcohol, obesity, and high cholesterol.

Coronary lesion means a blockage in a coronary artery, typically treated by either balloon angioplasty or coronary artery bypass graft.

Coronary revascularisation means treating blocked coronary arteries by either balloon angioplasty or coronary artery bypass graft.

Coronary thrombosis is a thrombus in a coronary artery, roughly the same as a heart attack.

Corticosteroids are explained under Allergy. Corticosteroids are any type of medication that contain steroids. Corticosteroids, often called steroids, are formed naturally in the adrenal glands – on each kidney, and their release is controlled by the pituitary gland, which is near the base of the brain.

Drug details are under prednisolone.

Side effects of oral corticosteroids taken short-term may include: an increase in appetite, weight gain, insomnia, fluid retention, and mood changes such as feeling irritable or anxious. Side effects of oral corticosteroids taken more than three months may include: osteoporosis (fragile bones), hypertension, diabetes, weight gain, increased vulnerability to infection, cataracts and glaucoma (eye disorders), thinning of the skin, bruising easily, and muscle weakness. While taking steroids, one's body reduces its production of natural steroids; so suddenly stopping taking them, one's body might not have enough steroids to work properly, maybe causing any of: fatigue, weight loss, nausea, dizziness, vomiting, diarrhoea, and abdominal pain. When one needs to stop the doctor will gradually reduce the amount of corticosteroids, so one's body can gradually increase its production of natural steroids.

Cortisol. See under Stress.

Coughing can be caused by a heart condition, eg when the chest is clear. It may be similar to unstable angina and breathlessness.

Coumarin. See under Anticoagulant.

COX. See COX under NSAIDs.

CPR stands for Cardio-pulmonary resuscitation.

Cranium The skull.

C-reactive protein (CRP) test. See polymyalgia, and creatine below.

Creatine (CRP) is an organic acid that occurs naturally in the body and helps to supply energy to cells. It is produced in the body in the kidney and liver from amino acids, which come mainly from meat and to a lesser extent from vegetables. Vegetarians usually have power creatine, but can get it from supplements. It is carried in the blood to muscles. Most of the creatine in the body is in the skeletal muscles - see creatinine below. Formula C4H9N3O2.

Creatinine is a breakdown product of creatine phosphate and is an important part of muscle. It can be tested for in a blood test and may indicate correct or abnormal kidney function.

CSF See cerebrospinal fluid under Meningitis.

Cubitus. Another name for Elbow.

CVD stands for Cardiovascular disease.

CVS = Cardiovascular system. See cardiovascular, system.

Cyanocobalamin is Vitamin B12, a complex red compound, occurring in liver. It is formed from carbon, hydrogen, oxygen, nitrogen, phosphorus, and cobalt. It is needed to form haemoglobin for red blood cells to carry oxygen. Shortage gives anaemia. See B12 under Vitamin for foods.

Cyanotic means the skin looks pale blue from reduced oxygen in the blood or from reduced circulation. See atrial septal defect.


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

We hope we have thanked everyone.

Richard Maddison

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