Glossary Of Terms - N

National Institute for health and Clinical Excellence Nausea Nebuliser Nephrology Nerves NICOR
Nitrates Nodal, node Non-opioids = NSAIDs and non-NSAIDs Non-steroidal anti-inflammatory drugs NSAID Normal distribution Nuclear medicine
Null hypothesis statistically significant Nicorandil Null hypothesis

Nail Finger and toe nails have a visible part and a root that is under a fold of skin. Also called unguis, onyx.

Narcotic generally means a potent and abused drug. Some narcotics are derived from poppies, and typically cause numbness, stupor, and/or abnormal behaviour.

National Institute for health and Clinical Excellence, NICE, is a group of experts who make recommendations on the uses of drugs and procedures, bearing in mind research findings, costs and benefits.

Nausea, nauseous means a feeling of perhaps being likely to be sick – to vomit. In the absence of food poisoning and illnesses, nausea may indicate some heart related condition. See Supraventricular tachycardia, and under shock.

Nebuliser is an aerosol form of a drug so it can be given within a facemask, to affect the lungs and airways. A hand-operated or electric pump mixes a small amount of the drug (from a suitable container with the drug as a liquid) as a mist with the oxygen to breathe.

Nefopam is a non-opioid analgesic similar to paracetamol.

Negative result of a test means that the condition is not occurring. The opposite, which the condition is present is called positive.

Nephrology is the study of kidneys and related health and diseases. Nephritis is inflammation of a kidney. See –itis.

Nerves are fibres that transmit sensory impulses. Sensory nerves transmit impulses representing eg touch, heat, taste, smell, or pain to the spinal cord or brain. Motor nerves transmit impulses representing movement to muscles.

Some movements are voluntary – ie you can consciously control them, eg movements of arms, legs and other parts of your body. Some movements are involuntary – ie you cannot consciously control them, eg heartbeats and digestion. Some normally continue without conscious thought but can be controlled, eg breathing.

Neural means of or relating to a nerve or the nervous system.

Neuralgia = severe spasmodic pain along one or more nerves. See neural, algia.

Neuritis is inflammation of a nerve or nerves, quite often also with pain and loss of function of the affected part of the body. See neural, -itis.

Neutraceutical means a food that provides health benefits.

Neutral has several meanings, including: not siding with a particular position; belonging to a neutral party; having no distinctive type, colour or quality; neither acidic nor alkaline; having no electrical charge or potential; having no effect on something; and other related meanings. The effect of a chemical may be neutralised by mixing it with some other chemical to counteract its effect.

Neutron See neutron under organic chemistry.

Niacin. See vitamin B3.

NICE stands for National Institute for health and Clinical Excellence.

NICOR stands for National Institute for Cardiovascular Outcomes Research. This is at UCL Institute of Cardiovascular Science, 2nd Floor, 1 St Martin’s le Grand, London EC1A 4NP. Tel 0203 108 7726. NICOR provides information to enable those who receive, deliver and commission healthcare to measure and improve services. NICOR publishes annual reports, including the April 2014 - March 2015 report on Myocardial Ischaemia National Audit Project - How the NHS cares for patients with heart attack, published January 2017. MINAP stands for Myocardial Ischaemia National Audit Project.

Nitrates are a group of drugs used to increase the blood supply to the heart muscle, and reduce the number of angina chest pain attacks. Nitrates are available in several forms:

GTN tablets or spray are put under the tongue to give immediate relief of pain. Both tablets and spray can be brought over the counter without a prescription. Tablets deteriorate once opened – typically they only keep for eight weeks. A spray canister may keep three years.

GTN patches are available for prevention of angina – worn during the day and removed overnight for maximum benefit.


Nitrates – Glyceryl trinitrate, GTN, as a spray, tablets, or a patch, is the commonest drug used for relieving stable angina chest pain. Preferably carry some with you at all times if you are likely to get angina or have a heart attack. You can use it before doing anything you know will bring on your chest pain. Do not suddenly stop using nitrates unless advised to do so by your doctor.

GTN is usually sucked as a tablet or sprayed under the tongue, and can stop such an angina attack quickly.

● One or two tablets or spray should relieve the pain within 5 minutes. Bite tablets into pieces. Do not swallow the tablet – it will not work. Sit down if possible. Once the pain is gone spit out the remainder of a tablet.

With a spray, remove the top, hold the spray upright with your finger on the button, and press the button firmly to spray one puff of medicine under your tongue. Close your mouth immediately. Never leave the pressurized container in the sun or a hot place. Do not damage or burn the can. Normal shelf life of GTN spray is 3 years, with a use by date.

● If the first tablet or spray have not relieved the pain after 5 minutes then repeat the dose, and again at 10 minutes.

● If the pain continues longer than 15 minutes, contact a doctor, or take the patient to A&E.

Keep tablets in their original bottle, & close the lid tightly. Store in a cool dark place. Do not carry the bottle close to your body – keep in a handbag or coat pocket. Discard GTN tablets eight weeks after the date of opening, even if you have only used a few tablets, as GTN tablets only keep that long after opening. They can be bought over the counter without a prescription.

GTN spray will typically last up to 200 sprays and keep for some years.

Nitrates – Isosorbide mononitrate, ISMN, ISMO, is a slow release tablet to prevent angina. ISMO (brand names Monit or Elantan), Isosorbide dinitrate (Cedocard, Isordil), and Isosorbide mononitrate slow release (IMDUR) tablets are taken regularly to prevent angina attacks occurring. They dilate the coronary arteries and so increase the blood supply to the heart muscle. The tablets should be swallowed whole with a glass of water and never crushed or chewed. If you, the patient, forget to take a dose, take it as soon as you remember. However if the next scheduled dose is due within 2 hours, or due within 6 hours for slow-release tablets, then skip the missed dose and take the next dose at the correct time. Do not take double doses.

Slight overdose of nitrates may unfortunately produce dizziness, headache, and drowsiness as a side effect due to the reduced blood pressure and reduced blood flow. This normally ceases after a few days as your body adjusts to the medicine.

An overdose can occur eg if a nurse starts the 4-hourly medicine rounds at alternate ends of the ward. Then a patient at one end of the ward gets the drug after 2 ½ or 3 hours and then 5 ½ or 6 hours alternately. After the two close doses the level of ISMO becomes too high, producing dizziness and headache. Indeed the patient may need oxygen until he or she recovers. This has actually happened.

Nocturnal dyspnea means night breathlessness. See HF diagnosis.

Nodal relating to a node. A node is any natural bulge, swelling or similar shape change in a part, structure, or similar. Eg a finger joint, lymphatic node.

Non-opioids = NSAIDs and non-NSAIDs. Non-opioids are not based on opium. The non-opioids divide into NSAIDs eg aspirin, and non-NSAIDs eg paracetamol. See non-opioids under Analgesic.

Non-opioids block the production of prostaglandins, so the nerve endings that would send pain messages to the brain are prevented from being stimulated. That is how eg paracetamol (explained under Analgesic) relieves pain and inflammation.

Paracetamol and nefopam are non-opioid non-NSAIDs.

Non-steroidal anti-inflammatory drugs, NSAID, relieve pain, inflammation, and/or swelling – usually of joints and/or muscles and reduce fever. This can happen after surgery.

They are called non-steroidal to distinguish them from corticosteroid drugs that are used to relieve inflammation.

Over 20 NSAIDs are available – eg aspirin, diclofenac, ibuprofen, naproxen. They are widely used for osteoarthritis and rheumatoid arthritis – reducing inflammation and thus relieving pain and swelling, but do not affect the progress of a disease. Other NSAIDs include: etodolac, fenbufen, fenoprofen, indometacin, ketoprufen, meloxicam, mefenamic acid, naproxen, and piroxicam.

Many NSAIDs interact with a wide range of other drugs including other NSAIDs, anticoagulants, & corticosteroids, and may increase the risk of bleeding and peptic ulcers.

The NSAIDs block the action of an enzyme called cyclo-oxygenase, COX. Research has shown that they block two types of COX: blocking COX-1 leads to the stomach irritation of NSAIDs; and blocking COX-2 leads to the anti-inflammatory effect.

A new class of NSAIDs, called COX-2 inhibitors, has been developed that block COX-2 but not COX-1, thus giving the benefits without the risk of stomach pain, peptic ulcers or intestinal bleeding.

One of the COX-2 inhibitors, with generic name rofecoxib, and with brand name Viaxx, was withdrawn in September 2004 – as soon as a research trial showed that it had twice the risk of triggering coronary heart disease than a dummy placebo. Dr David Graham, of the US Food and Drug Administration, discovered this; and estimated that between 88,000 and 140,000 Americans died or had heart attacks or strokes as a result of taking Viaxx since its launch in 1999 till 2006.

In September 2004 the European regulators launched a safety review of other arthritis drugs. Arthritis is an inflammation of joints, causing pain and stiffness. In December 2004 the UK Medicines and Healthcare products Regulatory Agency, MRHA, advised that some UK patients with heart disease or at risk of a stroke and taking certain arthritis drugs should change their medication.

Names of NSAIDs include:
Aceclofenac - brand name Hiffenac to relieve arthritis
Acemetacin - brand name Emflex and others - a COX2 inhibitor and antiinflammatory
Diflunisal - several generic versions available for inhibiting the production of prostaglandins, which regulate the contraction and relaxation of smooth muscles
Felbinac - for muscle inflammation and arthritis
Flurbiprofen - for arthritis pain - brand names Urbifen, Ansaid, Flurwood, Froben. Also an active ingredient is some throat lozenges eg Strepsils
Indometacin - to reduce fever, pain, stiffness and swelling
Nabumetone - to treat arthritis pain - brand names Relafen, Relifex and Gambaran
Sulindac - brand name Clinoril - for acute inflammations
Tenoxicam - brand name Mobiflex - to relieve inflammation, stiffness, swelling and arthritis pains
Tiaprofenic acid - of the profen class of chemicals - to relieve arthritic pain - brand names Surgam, Surgamyl and Tiaprofen.
Brand names of NSAIDs include: Etodolac; Fenbufen; Fenoprofen; Indometacin; Ketoprufen; Meloxicam; Mefenamic acid; Naproxen; and Piroxicam.
Names of COX2 inhibitors include: Celecoxib; Etodolac; Etoricoxib; Lumiracoxib.

Norepinephrine (previously called noradrenaline) is the main fight-or-flight hormone. See norepinephrine under Antidepressant. See also betablockers can nullify the effects.

Norepinephrine is a hormone secreted by the adrenal medulla. Like adrenaline it increases the heart rate and blood pressure, and it helps the endings of nerves to transmit impulses. See under Stress.

Here nor- means a chemical compound derived from some other compound by removal of a group. See under Stress.

Norfolk Zipper Club is a charity similar to the BCPA for people in Norfolk, and it raises money to buy equipment particularly for Papworth Hospital. The BCPA and NZC co-operate. Tel 01603 898551 Email:

Normal distribution. A normal distribution is a standard mathematical pattern that usually fits the collection of observed values of some variable for a group of patients. Eg the heights, or the systolic blood pressures, of a set of healthy adults of a particular age fit that pattern. It is a typical pattern with known properties. See mean under Average, and Standard deviation.

By contrast, the pattern of lengths of voice telephone calls – excluding email, internet and other computer connections – is not a normal distribution as there are many short calls and occasional very long ones.

Suppose many patients’ results for something have been measured, and suppose the mean is 100 and the SD is calculated to be 15, and suppose the observations fit a normal distribution.

● One SD below the mean is the value 85, and one SD above the mean is 115. The maths for a normal distribution gives that 34% – remembered as one-third – of the observed values will be from 85 to 100, and another 34% will be from 100 to 115. So about one-third of the observed patients will be within one SD on one side of the mean, and another 1/3 within one SD on the other side.

● Two SDs below the mean is the value 70, and two SDs above the mean is 130. The maths gives that 2.30% – remembered as nearly 2.5% – will be under 70, and similarly nearly 2.5% will be over 130. The probability of the next such patient being more than 2 SDs from the mean and on a particular side, eg over 130, is nearly 2.5% ie about 1 in 40.

NSAID. See Non-steroidal anti-inflammatory drugs.

Nuclear medicine. See also MIBI. Nuclear medicine is the medical use of radioactive substances for diagnosis. By injection into a vein, a patient is given a small quantity of a radioisotope or radionuclide. As its atoms or molecules decay they give off gamma rays that can be detected by a gamma camera with two screens at right angles. The computer system can calculate the exact position of the source, and thus build up images of the heart and other body organs.

The procedure is not dangerous – dosage is similar to other xray examinations. The value of the information gained far outweighs any risk. However, it is preferable not to perform radioactive scans during a pregnancy, nor when a mother is breast feeding as traces of the substance may pass into the breast milk and so to the baby.

Nucleus see nucleus under organic chemistry.

Null hypothesis. See under Statistically significant.

Nurofen is a brand name for an ibuprofen product.


This information was created and edited by Richard Maddison for the BCPA.
Copyright © 1997-2019 The British Cardiac Patients Association, and/or Richard Maddison.
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First published in this form 2002, and updated 2005, 2007, 2008, 2011, 2012, 2013, 2017.
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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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