Glossary Of Terms - S

Salt Sodium-based salt issues Potassium based salt Reduction of sodium-based salt Saphena Sarcoplasm
Saturated fat Saturation of peripheral oxygen Scleroprotein Secondary prevention Sedative Septicaemia
Septum Serotonin Severe Acute Respiratory Syndrome Shock Side effect Sino-atrial node
Sinus Sinus rhythm Smoking Passive smoking Shortness of breath SOB Sphincter
Spirometry Standard deviation Statin Side effects of statins Take both aspirin and a statin Starch
Statistically significant Statistical null hypothesis STEMI and nSTEMI Stenosed Stenosis Stent
Drug-Eluting Stent DES Sterilisation Sternum Stokes-Adams attack Stress Stroke
Subcutaneous Sucrose Sugar Supraventricular tachycardia Sudden arrhythmic death syndrome SADS Suture
Syndrome, Symptom, Sign Syncope, collapse System SSRI = Selective serotonin reuptake inhibitor, under Brand names of drugs.

S3 gallop = a particular extra sound from the heart caused by vibration of the ventricular wall when blood from the atrium hits the ventricular wall or something similar. See heart failure diagnosis.

Sac is a pouch, bag, or pouch-like part.

SADS = Sudden arrhythmic death syndrome.

Salt has two main meanings.

1 The usual food meaning is sodium chloride, used for seasoning and/or preserving.

2 Sodium chloride and potassium chloride are examples of a salt in chemistry. A salt is a compound formed from, or regarded as formed from, an acid and a base by replacing one or more of the hydrogen atoms in the acid molecules by positive ions from the base. See under Protein for explanation of the chemistry.

Most fresh food contains very little salt. Most of the salt people eat is in processed foods or salt added to food while cooking or at the table. Look at the labels on the food that you buy - if it says sodium chloride, sodium benzoate or monosodium glutamate then you may be getting extra salt without noticing. Do not add salt to food at the table.

Here we first explain sodium-based salt issues, then the potassium-based alternative, then reduction of the amount of salt consumed.

Salt - Sodium-based salt issues

The recommended daily allowance or limit for adults in the UK as advised by the Food Standards Agency is 6 g. Some experts suggest 5 g instead for women. For boys and girls aged 7 to 10 the recommendation is 5 g.

During exercise or on hot days people sweat a mixture that includes salt, so they may need more then. To maintain the body's amount of salt, they may need to intake some salt - and not just drink water.

Most UK adults and most older children are eating too much salt each day. Average adult consumption was 9.5 g a day (in 2004) and 8.6g in 2011.

Nowadays, foods have labels giving the sodium content: some also give the salt. To convert sodium to salt, multiply by 2.5. Eg 0.4g sodium has 1g salt. Giving the sodium on the package labels is legally required.

Diets too rich in salt are statistically significantly linked to increased risk of heart disease and stroke. The excess salt raises blood pressure and leads to strain on other body functions. High salt consumption is implicated in 220,000 deaths in the UK a year (2003-4 rate), mainly from increased risk of strokes associated with high blood pressure.

Since the 1950s or earlier, some medics and others have known both that many UK adults consume far more sodium-based salt than needed, and that it was bad for health. The sodium-based salt may cause or contribute to: strokes, heart conditions, and high blood pressure as above; and also to kidney problems, and possibly to cause excess fluid retention.

To some extent the kidneys and body generally can tolerate and get rid of some excess salt. Fully healthy people can dispose of excess salt. But people with high blood pressure may find a low-sodium salt diet beneficial.

In all the above, salt means sodium chloride, where the issue is the amount of sodium. The mechanism is believed to be that excessive sodium-based salt tends to cause high blood pressure and to make high blood pressure worse, and that this increases the stroke and heart risks as above. This leads on to the alternative below.

Salt - Potassium-based salt alternative. Experts believe that potassium-based salt does not have the same bad effects as sodium chloride.

For many years the BCPA and some other organizations have suggested that people with heart related conditions and/or high blood pressure should change to a product such as LoSalt, which has 66% potassium-chloride salt and 33.3% sodium-chloride salt. These two figures do not add to 100 since an anti-caking agent is added to ensure the product keeps. Such alternative products are often recommended for patients with diabetes, and/or kidney disorders, as well as for heart conditions, and/or high blood pressure.

Salt - Reduction of sodium-based salt

Statistical research and extrapolation has shown that if all UK adults could reduce their sodium-based salt intake to the recommended 6g a day, it would save 35,000 UK deaths per year (2004 figure).

The Food Standards Agency had a campaign to encourage people to reduce their salt intake and has asked manufacturers to reduce the salt in various foods. They recommend that adults should not have more than 6g of sodium-based salt per day. The average UK intake (in 2011) is 8.6g.

Unfortunately most bread is manufactured with a rather high sodium salt content. Typically an average slice has 0.2 g sodium = 0.5 g salt (in 2004). On average adults eat five slices per day, giving 2.5 g salt, which is 42% of the recommended salt intake of 6g. Eg Hovis white extra thick square cut has 1 g sodium-based salt per slice, so five slices gives 5 g - that alone is all or nearly all the recommended daily amount!

Crisps usually have too much salt, and are also bad for people in other ways.

Soups and sauces are an issue. At the end of 2004, the five soups highest in salt still contained 2.9 to 2.1 g per 200 g serving, while the lowest five had 1.0 to 1.2. Some are cup a soups, others tinned.

Unfortunately manufacturers cannot suddenly change the salt content because consumers expect the taste not to noticeably change, so changes can only be made gradually over years. 

The Food and Drink Federation in 2005 said that the industry has reduced the sodium in processed foods. The salt in soups and sauces was reduced by 10% in 2003 and a further 10% in 2004 - giving the new range from 2.9 to 1.0 above.

In 2011, following a research study, some doctors warned that too much sodium-based salt may raise the risk of Alzheimer's disease.

Saphena. A saphena is either of the two large veins of a leg that are near the surface. The plural is saphenae, from Latin. Eg a saphenous vein graft is a CABG using a vein from a leg.

Sarcoplasm is the protoplasm between the fibrils of muscle fibres. Sarcous = muscular, fleshy.

SARS stands for Severe Acute Respiratory Syndrome. See respiratory tract under lung.

Saturated. See saturated fat under Fats.

Saturation of peripheral oxygen SpO2 This measure of the oxygen content of the blood is by a gadget clipped to a finger and controlled by a computer. It is the percentage of the maximum that would be possible. Normal is 95-100%. Lower values mean that the blood does not have all that it could carry - perhaps indicating some heart or lung or cardiovascular disease.

The gadget transmits red and infrared light of various wavelengths through the finger. It detects the pulse, finds the minimum and maximum absorption, and distinguishes arterial from venous blood flows. From the differences it calculates the SpO2. In detail, it transmits different red and infrared wavelength signals and detects them after they pass through the finger or other tissue. It has to differentiate between arterial (oxyhaemoglobin) and venous (deoxygenated) blood. The transmission rates vary with wavelength. Thus the ratio can be calculated. See Blood oxygen.

SAVR see Surgical valve replacement.

Scleroprotein is any of a group of stable and insoluble proteins such as collagen, elastin, and keratin.

SD. See Standard deviation.

Secondary prevention. Once a patient has a disease he or she and/or others can try to stop it getting worse, or at least slow down its progress - called secondary prevention. Compare Primary prevention.

Sedative is a drug to reduce the activity of the central nervous system, making the patient somewhat sleepy.

Septicaemia is a bacterial infection that causes the immune system to go wrong and start to attack the body instead of giving protection. With 37,000 UK deaths per year, it is one of the commoner causes of death - after heart diseases, stroke, and cancer. It can enter the body through a wound.

Unfortunately the symptoms are hard for doctors, nurses and others to recognise. If the window of opportunity for successful treatment is missed, the bacteria in the blood cause many body functions to fail, and death follows. The symptoms include vomiting, diarrhoea, high temperature, fever, and unfortunately can be mistaken for flu.

The treatment is (and these six need to be given sufficiently early) oxygen, antibiotics, fluids, taking blood cultures to identify the specific bacteria involved, monitoring blood characteristics, and checking urine.

Experts think that if all medics and the general public always recognised the symptoms, and if patients got to hospital sufficiently early by ambulance, the death rate could be halved.

See also meningitis. If there is a skin rash, press a glass tumbler on the skin. If it is septicaemia or meningococcal meningitis the rash marks do not fade. If the marks do not fade, take to A&E without delay.

Septum. A septum is a dividing or separating wall between two organs of the body. Septal is the adjective, eg in Atrial septal defect and VSD = Ventricular septal defect. Most people with congenital heart disease lead full and active lives, but may need regular or occasional hospital checkups.

Serotonin is a chemical in the brain, intestine, and central nervous system, with formula C10H12N2O. It acts as a neurotransmitter, a transmitter of nerve impulses, and helps control mood and the body functions that work each day with the circadian rhythm - eg sleep pattern.

Severe Acute Respiratory Syndrome SARS means a serious breathing condition. See respiratory tract under lung.

Serous membrane. Serous is an adjective meaning containing serum - a clear watery liquid. See serous under lung. See also membrane.

Serum glutamic oxaloacetic transaminase SGOT See under Aspartate aminotransferase.

Shock is a serious condition, caused by illness and/or injuries. (We are not discussing electric shock or bad news here.) The main causes are:

- bleeding, fluid loss, including internal bleeding

- the heart being unable to pump enough blood around the body - eg in a heart attack

- an allergic reaction - called anaphylaxis.

The effect is not enough oxygen reaching vital organs - eg brain, heart muscles, lungs, kidneys. The body attempts to reduce the blood flow to other areas - eg skin, extremities, and less important organs - by narrowing arteries and capillaries.

The symptoms of shock are:

- pale and clammy skin

- increased and/or weak pulse / heartbeat rate, and/or increased breathing rate

- the patient may feel cold, dry-mouthed, nauseous (as though about to be sick); and be anxious, confused, irrational; with dropping level of consciousness and alertness.

Treatment includes:

- Reassure the patient. If possible deal with the cause of the shock.

- Let him / her lie down, or (if heart attack, chest injuries, breathing difficulties) sit in a half-sitting position with knees slightly bent and supported

- Keep him / her warm, eg with a blanket.

- If he / she is going to hospital and/or may need an anaesthetic, don't give food or drink - just moisten the lips if they feel thirsty.

S-ICD means Subcutaneous Implantable Cardio-Defibrillator.

Side effect. Many medicines may produce undesirable side effects (adverse effects). If you notice any undesirable side effects, you should contact your doctor.

Side effects include: drowsiness, dizziness eg on standing up, muddled thinking, unsteadiness eg leading to a fall, confusion, hangover in a morning, slurred speech, headaches, and/or pains.

Some of these effects, eg drowsiness, usually occur when a patient both drinks alcoholic drinks and takes a particular medicine, though the effects would not occur from either the alcohol or the medicine alone.

Some pairs of drugs and/or medicines interact when both are being taken. One doesn't work when in the presence of the other; and/or producing undesirable side effects such as those above.

The effects can often be avoided - eg by adjusting the dose, by following the instructions and regular timing accurately, by avoiding pairs of drugs that interact with each other, and by not taking other unprescribed medicines as well as the prescribed ones. Eg see Isosorbide mononitrate under Nitrates.

See ACE inhibitors side effects, antihistamines side effects, aspirin side effects, betablockers side effects, calcium channel blockers side effects, clopidogrel side effects, corticosteroids side effects, dipyridamole side effects, GTN side effects, mirtazapine side effects, potassium channel activators side effects, statins side effects, warfarin side effects.

In describing the frequency of side effects, the following are the meanings. However in this glossary I have sometimes written 'common' for very common or common, and written 'rare' for uncommon, rare and very rare.

- very common = probably affecting more than 1 in 10 patients, ie over 10%

- common = probably affecting over 1 in 100 patients, but less than 1 in 10, ie 1% to 10%

- uncommon = probably affecting over 1 in 1000 patients, but less than 1 in 100, ie 0.1% to 1%

- rare = probably affecting over 1 in 10,000 patients, but less than 1 in 1000, ie 0.01% to 0.1%

- very rare = probably affecting less than 1 in 10,000 patients, ie < 0.001%

Significant. See Statistically significant.

Signs. See signs under symptoms.

Sino-atrial node. The sino-atrial node is the place in the heart where the electrical impulses for each beat begin. They spread through the heart causing it to contract so that blood is pumped to the lungs and the rest of the body.

Sinus means any hollow space or cavity in a body eg a nasal (of the nose) sinus; or eg a large channel for venous blood between the brain and the skull. Sinusitis is an inflammation of the membrane lining the nasal sinus.

Sinus rhythm is the normal heart rhythm.

Slow release. See under half-life.

Smoking removes oxygen from the blood, excites the heart, and makes blood cells stick together. This often leads to high blood pressure, heart and/or lung diseases, stroke, and/or earlier death.

See separate factsheet on Benefits of stopping smoking.

Passive smoking = breathing the smoke from other people - affects both adults and children, giving them increased risk of heart disease, lung disease, stroke, and/or earlier death.

The British Heart Foundation National Centre for Physical Activity and Health at Loughborough, BHFNC, found that 19% of CHD deaths are related to smoking.

22% of the UK population over 16 smoke (2007 figure). This percentage has been dropping gradually over many years. The ban on smoking in public places helped many people to stop.

Smooth muscle is muscle that can do slow rhythmic contractions involuntarily (not requiring conscious thought). They occur in arteries, veins, the walls of blood vessels, heart muscles, alimentary canal, and some other parts of the body.

SOB = Shortness of breath. See Breathlessness. SOBOE = Shortness of breath on exertion / exercise.

Sodium. See under salt and minerals.

Sources. In many cases the BCPA Journal articles give sources and further information than these Glossary entries. There is an index to BCPA Journal articles in this Glossary.

Specialist Registrar, a hospital appointment next below consultant, eg specialising in cardiology.

Sphincter is a ring of muscle surrounding an opening in an organ of the body. The sphincter muscle can contract to close the opening. Eg: where pharynx and oesophagus to control swallowing; where oesophagus enters stomach; bladder control; anus; bile and pancreas passages to the duodenum.

Spirometry is measuring the volume of air capacity of the lungs. The instrument is a spirometer.

SpR = Specialist Registrar, eg specialising in cardiology.

SR means sinus rhythm (the normal heart rhythm), or slow release drug. MR means medium release drug.

SSRI = Selective serotonin reuptake inhibitor, under Brand names of drugs and scroll down.

Stable angina. See Angina.

Standard deviation, SD, is a measure of how far a set of observed values spread on either side of their mean. Eg the set of five values 79, 89, 100, 111, 121 has mean 100, and the SD is calculated to be 15. The SD calculation depends on differences of the values from the mean - eg 79 and 89 are roughly 15 below 100, and 111 and 121 are roughly 15 above. See normal distribution.

Starch. See under sugar.

Statin. Statins are lipid-regulating medicines - lipid-lowering tablets. Statins work by reducing cholesterol production by blocking an enzyme found in the liver. Thus they slow the progression of heart disease. About 8 million UK adults take statins. Statins are used to:

- reduce too-high cholesterol in the blood

- reduce the risk of a heart attack or damage to the heart by on average about 20% - this is averaged over men and women. One study found that statins were more effective on men than on women*. But that conflicts with other studies that found statins effective on both men and women preventing heart patients from developing further heart problems. The explanation of the misleading and wrong * assertion is that the research sample size was relatively small, had relatively few women and was biased as they mostly had had strokes.

- reduce the risk of stroke

- lower the triglycerides in the blood

- reduce the risk of dying from any cardiovascular cause

- generally reduce the risk of any major vascular event - coronary deaths, heart attacks, strokes, and coronary revascularisations. Research trials have shown that statins do these. There is also a proportional reduction of risk in low-risk patients, ie those with a five-year risk of any major vascular event of less than 10%. See BCPA J188p4 for details.

They are used when a low-fat diet and other non-medical treatments such as exercise and changes to life style have not been sufficient or have failed. Some experts say they are the most effective drugs for lowering the LDL.

Various statins are available.

Brand names of statins
Atorvastatin - brand name Lipitor, on which the patent expired in 2012 so it is now much cheaper.
Fluvastatin - brand name Lescol
Simvastatin - brand name Zocor
Pravastatin - brand name Lipostat
Cerivastatin - brand name Lipobay
Rosuvastatin - brand name Crestor.

Statins are normally taken once a day, with the dose taken in the evening or at night. Exceptionally Atorvastatin is taken in the morning as it can cause insomnia if taken later in the day. You should swallow the tablets whole with a drink of water. These tablets are used in combination with a diet that is low in saturated fat. You can get dietary advice from a dietician or cardiac nurse or from leaflets.

Some statins, eg atorvastatin and rosuvastatin, may also reverse the build-up of deposits in the arteries. About a million UK adults take statins (2002 figure).

Other research suggests from statistical analysis that patients who had taken statins had lower risks of colon cancer and of prostate cancer than patients who had taken other cholesterol-lowering drugs or neither. But researchers do not yet (2004) know how they could have this effect.

Side effects of statins are rare, but occasionally people may:

- suffer headaches or stomach problems - such as heartburn, nausea, constipation, or diarrhoea and flatulence.

- experience muscle inflammation although this is extremely rare. You should tell your doctor if you have any unexpected muscle pain, tenderness or weakness.

Do not stop taking statins suddenly unless advised to do so by your doctor.

Take both aspirin and a statin. Five major US trials involving 140,000 people showed the following.

- The risk of a heart attack was reduced by 31% when pravastatin was taken daily with aspirin, as compared with those taking aspirin alone.

- Also the risk of a heart attack was reduced by 26% by taking both as compared with taking pravastatin alone.

- Also, strokes that resulted from fatty cholesterol deposits lining the walls of the arteries in the brain were about 30% less among those taking both than in the groups taking only aspirin or only a statin.

These results strongly support current advice for the treatment of CHD and of cerebrovascular disease to take both aspirin and a statin. This advice is likely to prevent thousands of premature deaths. See death rates statistics.

Statistically significant. In a research trial, or from observations of many patients who differ in some way, statisticians can calculate the probability of a null hypothesis.

A null hypothesis is an assertion that there is no association between certain observable and/or measurable factors or variables - particularly where experts expect that there is an association and their research aim is to investigate.

Eg a null hypothesis might be that smoking during pregnancy does not affect baby weight at birth, excluding twins, triplets, quads, and births before 28 weeks - so the baby weights of smokers and non-smokers with the same duration of pregnancy would be equal.

The mean of a set of observed values may be very different from what would be expected under the null hypothesis. Or the pattern of observed values in a table with rows and columns corresponding to two variables may be different from what would be expected values under the null hypothesis. Or the difference between the means of two groups may be significant, as below.

If the probability P of the observed values occurring by chance is small, then that finding is regarded as statistically significant - strongly suggesting that the null hypothesis is false.

To some statisticians: P less than 0.05 = 5% is called significant and denoted by *; less than 0.01 = 1% is highly significant and denoted by **; and less than 0.1% = 1 in 1000 is even higher and denoted by *** as below. Others sometimes use these terms slightly differently. The criterion of what probability is regarded as significant is ultimately arbitrary. It is preferable for the actual percentage to be given in research results.

A phrase such as research does not show or no significant difference was observed typically means that this was properly investigated and the probability P of the observations occurring by chance was not statistically significant - eg greater than 5%.

From the results of about 2200 pregnancies, the differences of the means of the baby weights of smokers and of non-smokers for various durations of pregnancy were as follows. The smokers' babies were less weight in all cases. Twins and births before 28 weeks were excluded, and every cell was the mean of at least 50 babies.

- For 28 to under 36 weeks 3.9 oz (not statistically significant)

- For 36 to under 38 weeks 6.2 oz * (P less than 0.05, significant)

- For 38- weeks 7.0 oz *** (P less than 0.001, highly significant; being 112.5 ± v 105.5 ± 18.3)

- For 40- weeks 5.9 oz *** (P less than 0.001, highly significant; being 122.2 ±16.8 v 116.3 ± 17.0)

- For 42 and over weeks 2.5 oz (not statistically significant).

The above findings alone are not enough to deduce much.

Researchers normally investigate further. Similar results were found when boys and girls are considered separately. Also, similar results occur when excluding various combinations of: diabetics, mothers less than 5 feet tall, coloured women, mothers whose partners belonged to the lowest social class, and/or mothers whose fathers belonged to the lowest social class. In every comparison the smokers had smaller weight babies. Also, the smoking mothers were divided into groups. For example occasional smokers and regular of about than five a day taken together, were compared with 10-a-day, and 20-a-day or heavier smokers taken together. Comparing these different smoking patterns, there was little difference between the baby weights - so whether the mother smoked at all is more important than how heavily. The team researched the medical reasons for the differences between these groups, and the effects of all the various factors mentioned in this paragraph.

The research team spent several years investigating many other factors not mentioned above before fully concluding that maternal smoking during pregnancy may damage a baby's health.

STEMI and n-STEMI. STEMI and non-STEMI, nSTEMI, are particular patterns that can be seen on a full ECG.

Heart attack patients may be divided into those with, and those without, ST segment elevation visible on the ECG. This leads to the final diagnosis, once the blood test confirms a heart attack has occurred, of ST-elevation myocardial infarction (STEMI) or non-ST elevation myocardial infarction (nSTEMI). ST-elevation usually means that a coronary artery is completely blocked - in most cases, this requires immediate treatment to re-open the artery. The absence of ST-elevation usually means that the coronary artery is only partly blocked.

Although patients with STEMI are at greater early risk, the medium to long-term outcome (in terms of recurrent heart attack or death) is in fact worse for those with nSTEMI. The nSTEMI patients make up the majority of heart attacks. Like those with STEMI, they are likely to have better outcomes if they receive a prompt angiogram and treatment to restore blood supply to the heart.

Patients suffering non-ST-elevation myocardial infarction (nSTEMI), may not require such urgent treatment but often have a worse long-term prognosis. Year-on-year there are increases in the proportion of nSTEMI patients being admitted to a cardiac unit, being seen by a cardiologist and being referred for angiography b all measures that are linked to better patient outcomes. Importantly, of those patients admitted directly to a hospital that has angiography capability, only 55.8% of nSTEMI patients had an angiogram within the recommended 72 hours of admission to hospital. Source: MINAP 2014-15 annual report. Myocardial Ischaemia National Audit Project b How the NHS cares for patients with heart attack. 52pp. Published about late January 2017.

Stenosed means restricted or narrowed, eg a narrowed artery or valve. See Restenosis, Artery and/or Valve.

Stenosis, its effects and treatment are under Coronary heart disease. See also aortic stenosis.

Stent. In some patients with a blocked artery, surgery may be avoided by inserting a stent, which is rather like a small, coiled, stainless steel spring. It is placed, using an angioplasty catheter, in the blocked or collapsed section of the artery. When it is released from the catheter, the spring expands and holds the artery open.

Unfortunately, after angioplasty and a bare-metal stent BMS, such as widely used up to about 2003, about 30% of patients develop renarrowing of the artery - called Restenosis.

A drug-eluting stent, DES, has a coating of a drug on the stent. It prevents or reduces the occurrence of restenosis; ie gives lower risk of the artery renarrowing. In a clinical trial of a drug-eluting stent, no patient (0%) had renarrowing within two years. By 2004 to 2007 research had showed that patients with a DES had about a quarter or less chance of needing restenosis as compared with patients with BMS. DESs cost about B#600 and BMSs about B#300 (2007-8 prices). See Coronary angioplasty - success.

DESs are particularly useful where the Coronary arteries are very small, or where there are long sections of the coronary artery that need to be covered with the stent.

The National Institute for health and Clinical Excellence NICE in February 2008 recommended that DESs be used in percutaneous coronary intervention only if both

- the artery to be treated has less than 3mm calibre or the lesion is longer than 15 mm; and

- the price difference between DES and BMS is no more than B#300.

Sterilisation. Papworth Hospital Sterilisation Services Department employs 8 or 9 highly-qualified staff. They use over a million pounds worth of equipment to ensure that every item used in theatres is germ-free for each patient. Papworth has a thousand or so such articles. Each item is uniquely identified and a record is kept for traceability purposes as it goes through the processes and the theatres.

Sternum. The sternum is the breastbone, the long flat vertical bone at the front of the chest to which the collarbone and the upper-seven pairs of ribs join.

Steroids and sterols are explained under Allergy. Steroid is another name for corticosteroid. See also cholesterol.

Stokes-Adams attack. A Stokes-Adams attack is a fainting spell resulting from a temporary decrease in blood flow to the brain, usually associated with heartblock.

Storing medicines. See Medicines - taking and storing.

Stress. Stress occurs when the physical, emotional, health/disease, or mental pressures on a person exceed what he or she can cope with.

The body responds by a natural survival mechanism -releasing the hormones adrenaline, noradrenaline, cortisol, and/or adrenocorticotrophin. These prepare the heart, brain, and body to do whatever may be needed - eg raise heart rate, breathe faster deeper, widen pupils, increase sweating, mind alertness, more blood flow to muscles, and/or increased blood sugar/glucose. The body becomes prepared for physical exertion. If the body did not so respond the result might be damaging to health.

If the cause is not health/disease, taking slow deep breaths may help one to calm down and think and deal better with the situation.

If the stress continues over some time, eg from stress at work or after a heart attack, the person may feel irritable, aggressive, or angry, or not sleep well - particularly where he or she cannot or does not take regular exercise. In exercise the muscles release the effects of the body's response. Normal physical and daily activities, walking, and talking to people all help rehabilitation and recovery.

Slight stress can be good for a person if he or she allows the body's natural responses to be relieved by activity. Unfortunately, adrenocorticotrophin slows down production of white blood cells, thus reducing one's ability to fight infection.

See also Epinephrine which describes that drug given in an emergency to stimulate heart activity and raise low blood pressure

Stroke. A stroke is when the blood supply to part of the brain is suddenly and seriously impaired by a blood clot or damage to an artery. The patient may have a sudden severe headache; be in a confused emotional state; seem to be drunk; gradually or suddenly go unconscious; and/or have weakness, drooping, dribbling mouth, slurred speech, loss of movement, unequal size pupils, and/or loss of bladder or bowel control.

It often results in unconsciousness and/or paralysis.

Among adults, stroke is the commonest cause of disability in the world.

People who have had a heart attack have increased risk of having a stroke; and vice versa.

Ischaemic stroke is not enough blood. Haemorrhagic stroke is bleeding from ruptured blood vessel

Treatment of stroke: If unconscious: open the airway; check breathing; loosen clothing if needed; 999 for ambulance; resuscitate if necessary; and record breathing and pulse every ten minutes.

If conscious: ask for consent if needed; lay down perhaps with head and shoulders slightly raised; 999 for ambulance; put a cloth or towel to absorb any dribbling; do not give food or drink.

Each year about 130,000 UK people suffer a stroke. About 10,000 of these are under retirement age. If binge drinking leads to a stroke it could mean a longterm disability or even death, according to The Stroke Association.

Stroke is the only neurologic disorder that physicians can completely reverse the disabling effects of with thrombolysis. Thrombolysis means injecting a drug such as alteplase that dissolves blood clots that have already formed.

See also Transient ischaemic attack, collapse blackout syncope fall.

Subclavian (applied to an artery or vein) means situated below a clavicle. A clavicle is a bone that connects the shoulder blades with the upper part of the sternum / breastbone. There is one each side.

Subcutaneous means under the skin - eg injecting through the skin.

Subcutaneous implantable cardio-defibrillator S-ICD. Most ICDs have at least one lead going directly into the heart eg through a vein, to detect any badly wrong rhythm - thus triggering a life-saving shock to restart the heart correctly.

The S-ICD has a wire across the chest just below the skin and connected to the device so as to deliver the shock. The shock has to be more powerful as the wire is not within the heart.

One advantage is that the wire is less likely to cause an infection, which sometimes occurs with the lead going through a vein and into the heart. Another advantage is that the device is less likely to give a false shock - being slightly further from the heart means it is less likely to pick up a wrong signal such as electrical noise.

Dr Andrew Grace, at Papworth Hospital, helped develop the S-ICD and implants them for appropriate patients.

Sublingual means under the tongue.

Sudden arrhythmic death syndrome SADS is a rare death from an irregular heart rhythm that can make the heart stop. It can occur in people of any age, with no symptoms till it death occurs without warning.


Sugar is a general term for various types of sweet-tasting carbohydrate. For rate of digestion see Glycaemic Index.

- Glucose is the type of sugar in the blood - giving energy for muscles and metabolism; and in bread, pasta, potatoes, rice, pulses, whole grains, and cereals. Formula C6H12O6.

- Starch is a form of glucose occurring in plants - eg rice and potatoes.

- Fructose is the form of sugar in fruit and honey.

- Lactose is the form of sugar in milk.

- Sucrose is the common form of sugar - granulated and caster; and used in drinks, cakes, and confectionery. It is extracted from sugar cane and/or beet.

The body acts slightly differently with fructose from the others. The liver converts fructose into body fat; and fructose does not cause a message to the brain saying 'Stop eating now, you've eaten enough'. For the other sugars - starch, lactose & sucrose - the liver decides whether to convert to glucose to supply energy into the blood for muscles and body needs or whether to convert the sugar into body fat; and the brain gets a message saying 'Stop eating now, you've eaten enough'.

Superior means either greater quantity or quality; or situated higher up, above or upper in position. Opposite of Inferior.

Supraventricular tachycardia, SVT, means the heart is beating too fast and irregularly. Instead of the normal heart rate of about 60 to 80 beats per minute, it is from 140 to 200. It may be caused by too much stress, coffee, smoking, or alcohol; or by viral infections. It may occur spontaneously, or may occur by the rate not returning to normal when resting after exercise.

The symptoms include any of: breathlessness, sweating, chest pain, and the high pulse; possibly with nausea, faintness or dizziness. It may be like atrial fibrillation, atrial flutter, or nodal tachycardia.

Surgeons are doctors who do operations. Patients should not chose between them based on published patient death rates or even on the rates of whole cardiac departments, as the raw data fails to allow for risk - some surgeons operate on severe cases where patients have greater chances of dying.

Surgery is the branch of medicine involving treating disease or injuries by operations involving incisions, eg cutting into the body. It also means the performance of such operations by a surgeon. The word surgery is also used for a place where a doctor or dentist sees patients.

Surgical aortic valve replacement SAVR is done through an open-heart procedure. It has been performed for many years. The surgeon removes the narrowed valve and replaces it with either a mechanical valve or a biological valve made from animal or human tissue. See BCPA journal index Aortic stenosis and its treatment J183p8-9.

Suture has several meanings.

1 A surgical seam formed after joining two surfaces.

2 A thread to sew together two surfaces with stitches - made from catgut, silk thread, or a collagen that is gradually absorbed over say three months.

3 A kind of immovable joint - eg between the three skull bones that fuse together after birth.

4 To join together as any of the above.

Sweat is salt and other body salts in water, produced by sweat glands under the skin and carried to the surface by sweat ducts. As sweat evaporates it cools the skin and thus reduces body temperature by the blood flowing near being cooled. As the mixture includes salt, on hot days people may need more salt then - see Salt - Sodium-based salt issues. To experience this, when you are sweating, wipe your finger on the skin to collect some sweat and put it on your tongue - you should taste the salt.

SVC. See Vena cava.

SVT. See Supraventricular tachycardia.


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.

* sometimes means multiply.

Syndrome means a combination of symptoms - what the patient says and/or experiences such as a change in some body function; and signs b what a medic, first aider or carer observe as objective evidence; together indicating some disease, condition, or problem.

Symptoms. The symptoms of an injury or disease are the sensations that the patient experiences and can describe, such as a change in some body function.

Signs are issues about the patient that a medic, first aider or carer can see, feel, hear, smell, and/or observe as objective evidence - either being obvious or observed from examination or tests.

Sometimes, particularly where the difference is not relevant, the term symptoms is used to cover both.

Syncope. See syncope under collapse.

Syndrome is any combination of signs and symptoms that indicate a medical condition or disease.

System. The systems approach to understanding how things work is based on two ideas.

1 The real world can be thought of as having purposeful human activity systems that are of interest. These systems interact with each other and with the natural, economic, political, social, and other environments in which they are embedded. Each system can adapt to external changes.

2 A system may be viewed as having several parts or components. Each part contributes to the purpose of the whole. So the whole would be affected if a part were to leave the system. Each part has interfaces to other parts and/or external systems, and can adapt to changes external to itself. The parts are subsystems.

Thus a system is an assembly of parts or components connected together in an organized way. The parts are affected by being in the system and the behaviour of the system is changed if they leave it. This organized assembly of parts does something; and is regarded as being of particular interest. The subsystems contribute to the purpose, interact and can adapt.

The systems and subsystems are constructs of human minds that perceive them as of interest. Different people looking at the same things will often see quite different systems and quite different purposes.

The main human body systems are: cardiovascular system, digestive system, endocrine system, immune system (to protect from disease), integumentary system (skin, hair, nails to prevent damage), lymphatic system (to remove excess fluids, absorb fatty acids, carry fat around, and part of immune system), muscular system, nervous system, reproductive system, respiratory system, skeletal system (skeleton, bones, body shape), urinary system.

Systolic. See Blood pressure. For systolic heart failure see Heart failure terms.


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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