Glossary Of Terms - H
Haem means the red pigment containing ferrous iron present in haemoglobin in blood. The US spelling of English words haem- (or haema- or haemo- before a vowel) is hem- (or hema- or hemo-). Ferrous means the iron is divalent (a valency of 2) in the compound. Ferric means the iron is trivalent (a valency of 3) in the compound.
Haemato- means indicating blood or resembling blood. The adjective is haematoid.
Haematology means the study of blood, blood tissues, and blood diseases, including taking blood samples and analysing them.
Haemoglobin is the component of blood that carries oxygen from the lungs to other tissues. It combines with oxygen in the lungs where the oxygen concentration is high, and releases it to tissues where the concentration is low. Shortage gives anaemia.
Haematosis is the process of adding oxygen to the venous blood in the lungs.
Haemorrhage The adjective is haemorrhagic. Bleeding from a ruptured blood vessel. Haemorrhagic stroke is internal bleeding in a blood vessel supplying blood to the brain.
Half-life is the time for a drug concentration in blood to drop to half its initial concentration. More widely in science it is the time for half of a gradual physical or chemical process to occur – eg for half of a quantity of a radioactive substance to change. After a further equal amount of time there will be a quarter of the original still unchanged. An equal time later there will remain one eighth.
Slow release tablets are arranged so they have an appropriate half-life – eg the surface has something that controls the rate. Hence patients can take the tablets at regular intervals and get an appropriate concentration of the drug in their body.
Handicap. See Handicap under Impairment.
Hazard ratio HR is the ratio of the risk of some outcome relative to unit risk of some other outcome such as with a placebo or equivalent.
For example, suppose we want to explain by how much eating more fruit and vegetables daily reduces the risk of stroke. A study of many thousands of people followed for many years gave various figures. We adjust the figures so those eating less than 3 a day had unit risk of stroke. Then those eating 3 to 5 a day had a relative risk of HR = 0.89 (confidence interval range 0.83 to 0.97). And those having more than 5 a day had a relative risk of 0.74 – a 26% reduction (CI 0.69 to 0.79).
HDL. See Cholesterol HDL under Cholesterol.
Health. A general term for the condition of the body and mind – eg relating to the presence or absence of disease, illness, or injury.
Health. Ten steps to a healthier heart. The recommendations below are aimed at preventing or reducing the risks of heart disease. The diet items do not apply to children under five years old or to people training for sports.
1 If you smoke – stop.
2 Eat at least five portions of fruit and/or vegetables each day.
3 Reduce or keep down total fat consumption, and in particular intake of saturated fat. Replace saturated fat with polyunsaturated and/or mono-unsaturated fats. For example try a cholesterol-lowering product such as Flora pro.activ® or Benecol®. This is available as: a low-fat spread, a milk drink, or a yogurt. You should aim for three portions per day.
4 Plan meals in advance and check nutrition labels. These can sometimes be surprising.
5 Include fresh or frozen oily fish in your diet at least twice a week. The main sources of omega-3 are fresh or frozen: salmon, pilchards, tuna, sardines, mackerel, and similar fish.
6 Eat plenty of foods rich in carbohydrate like bread, pasta, rice and potatoes. Avoid or reduce sugar, cakes and biscuits. See GI.
7 Minimize your salt intake.
8 Moderate levels of alcohol provide protective cardiac health benefits, particularly to those at risk from coronary heart disease. Chardonnay and red wines are suggested.
9 Make sure you have a balanced diet and include an intake of essential vitamins, minerals and proteins.
10 Achieve and maintain a healthy body weight.
If you are slightly overweight, suggestions include
- try increasing your intake of proteins – white meat, oily fish, eggs, low-fat cheese, milk – skimmed or semi-skimmed. That may help you reduce your total carbohydrates and fats.
- Also try making small adjustments – eg one less spoonful of sugar, one less cake, potato, a few less chips.
Healthcare Commission. This is the independent inspection body for the NHS and the private and voluntary healthcare sectors in England & Wales. It aims to ensure quality and promote improvements. It has a legal obligation to report to the Secretary of State significant failings and recommendation for special measures. Special measures are produce improvements where other normal methods have failed or are considered likely to fail.
Heart. The heart is the organ that pumps blood round the body. It is about the size of a fist, behind the breastbone / sternum, and nearly central but slightly to the left. It has four chambers, four valves to prevent flows in the wrong direction, and muscles. See Atrium, Ventricle, Valve, and Coronary arteries.
The heart muscles are supplied with blood through three arteries – the back left, the front left and the right. Each of the three branch into a network of smaller arteries and capillaries. This system of arteries and branches is called the Coronary arteries. All three are fed as branches coming off the aorta, which is the main artery carrying blood from the left ventricle to the rest of the body.
The commonest cause of damage to the heart is a heart attack. Damage can also be due to high blood pressure, hardening of the coronary arteries, narrow or leaking valves, and/or excess alcohol drunk over several years.
High blood cholesterol may also cause narrowing of and deposits in the arteries, including the coronary arteries. Atherosclerosis means narrowing and thickening of arteries due to the build-up of cholesterol and other cells.
Heart attack. The following terms essentially mean the same thing as heart attack: coronary, coronary thrombosis, infarct; and myocardial infarction MI (which really means destruction of an area of heart muscle as a result of obstruction of a coronary artery).
See separate factsheet on Heart Attack, and Exercise plan after a heart attack.
A heart attack is the effect of an artery becoming blocked or significantly narrowed by a clot forming in a coronary artery – one of the arteries supplying the heart. The clot interrupts blood flow to the heart muscles, so an area of heart muscle is deprived of adequate blood. This may cause permanent scarring and damage to an area of the heart muscle.
This causes a lack of oxygen in a part of the heart, which then becomes less able to work effectively and scarred – possibly permanent scarring in the affected area. Adverse chemicals build up, and pain is felt. The rest of the patient's heart now has to work harder to get used to the extra workload.
This clot may occur suddenly. The patient feels a persistent vice-like central chest pain, which may spread to the left arm and/or the neck and jaw; is breathless; may suddenly faint or collapse; and has rapid or weakening pulse. Unlike stable angina the pain does not ease when the patient is at rest. Some people have a ‘silent’ heart attack in which they feel no pain.
In a heart attack the patient's heart does not usually completely stop beating. The heart attack may cause permanent scarring and damage to an area of the heart muscle.
Each year over 200 000 people in the UK have heart attacks. In the UK, heart and circulatory diseases are the biggest killer. About 110 000 to 120 000 people die from coronary heart disease per year in the UK. Coronary heart disease is the commonest cause of premature death in the UK. Many deaths are preventable. See death rates.
Many heart attacks occur away from hospitals. Many occur within the first few minutes of the symptoms. Prompt access to the right treatment can mean the difference between living and dying. This means CPR, defibrillation and immediate transfer to hospital.
Each year about 20 000 people in the UK develop angina for the first time.
Most women imagine that heart disease affects men only. In fact, one in four women die through heart disease. Heart disease here means damage to the heart caused by narrowing of the coronary arteries. At first there may not be any noticeable symptoms. As it progresses it can lead to angina chest pain; and if an artery becomes blocked then part of the heart dies, leading to a heart attack.
Heartbeat. The word heartbeat means either an individual beat of the heart, or the heart rate.
Heartblock is a condition in which the electrical impulses from the atria – upper chambers of the heart are not transmitted correctly to the ventricles – lower chambers of the heart, causing a slow heart rhythm. Some patients do not need much treatment; some have dizziness and/or fainting; and some need drugs or a pacemaker.
Heartburn is a burning acrid feeling in the throat, and nothing to do with the heart. This may occur during pregnancy or to people who are overweight and/or smoke. Preferably do not eat late into the evening just before going to bed, reduce alcohol if any, reduce spicy foods if any, and at night prop oneself up with pillows. Maybe try any medicine for excess stomach acidity – ask a pharmacist.
Heart condition is a very general term for any heart-related condition, disease, disorder, or abnormality.
Heart disease is a general term for any undesirable heart condition such as Coronary heart disease.
At least 2.7 million UK people face severe disability through the irreversible effects of heart disease.
Heart diseases may be due to any combination of: alcohol use; anabolic steroid use; atherosclerosis; autoimmune conditions; bacterial infection; cocaine; congenital abnormalities; diabetes; diet - eg when high in saturated fat and cholesterol; hypertension; injury; sedentary lifestyle; smoking; thyroid dysfunction; toxins; and/or viral infection.
Heart failure means that the heart muscles cannot pump enough blood efficiently to meet the body's needs. It does not mean that the heart has stopped. Most cases are due to coronary heart disease, but about one-third of cases are due to high blood pressure. With mild severity, there will be almost no symptoms, whereas more severe cases may have breathlessness, swelling of the ankles and general tiredness. With appropriate treatment patients can usually adjust to their condition and live with it.
It was estimated that about 650,000 people in the UK had some form of heart failure (in 2004). These cost the NHS about £625 million a year. Many have mild severity, almost no symptoms, and hence are not seeing a doctor.
The following is based on my book review of Fast Facts: Heart Failure by Dariusz Korczyk et al. Health Press Limited, Elizabeth House, Queen Street, Abingdon, OX14 3LN. First edn Aug 2012, ISBN 978-1-908541-28-4, A5, 138 pages.
In the last 30 years new treatments, drugs, operations and devices have been developed, with much better understanding of the mechanisms and outcomes of heart failure (HF). These have hugely improved the outcomes and wellbeing of H-F patients. This book explains mechanisms, causes, prevention, treatments, and patient management. It is written for healthcare professionals working in primary care, cardiac nurses, junior hospital doctors, medical students and cardiology trainees. Its all written using medical terms, so would not be easy for non-medics to read. In what follows I have reworded it into more lay language. Medics should not rely on this wording.
Heart failure terms
The term heart failure means the heart function is not sufficient to meet the needs of the body's tissues. Medics distinguish the following.
- Diastolic versus systolic. Ejection fraction is the percentage of blood pumped from the ventricles with each heartbeat. Over about 50% is normal. Systolic HF means not enough, eg 40% or less, pumped from the left ventricle, caused by destruction of an area of heart muscle from obstruction of a coronary artery. Diastolic HF is caused by abnormal suction of blood from the left atrium to the left ventricle, giving high diastolic blood pressure.
- Acute versus chronic. Acute HF means having a sudden onset or gradual worsening leading to hospital admission. Chronic HF, CHF means gradual worsening of breathlessness at night or with some of the other major and/or minor criteria below. Chronic means continuing for a long time and/or continually recurring.
- Right versus left, and biventricular. Left ventricular HF, LVHF is the commonest form of HF, eg with breathlessness on exertion and/or at night. Right ventricular HF, RVHF is most commonly caused by the left ventricular HF with ankle swelling, swollen neck veins (see below), and other symptoms. Biventricular HF means both ventricles.
- High versus low output. Low output HF gives pale cool extremities. High output HF gives warm extremities.
Heart failure diagnosis
The major criteria for diagnosis of HF are:
- night breathlessness (= nocturnal dyspnea)
- swollen neck veins (= venous distension / hepatojugular reflux)
- crackles or excess fluid in the lung tissues (crackles or pulmonary oedema)
- enlarged heart (= cardiomegaly on chest radiography)
- 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 (= S3 gallop).
There are minor criteria: high heartrate (= tachycardia); excess fluid in the tissues of the ankles (= bilateral ankle oedema); breathlessness on exertion (= exertional dyspnea); coughing at night (= nocturnal cough); enlarged liver (= hepatomegaly); reduction of vital capacity.
Diagnosis of HF requires either two major or one major and two minor criteria being present.
Conditions for heart failure
Coronary artery disease, high blood pressure, heart valve disease, and diabetes are the four most important predisposing conditions for the development of HF.
HF is a disease where the body doesn't adapt appropriately to injury such as something reducing the blood circulation and/or pump failure. Thus the load on the failing heart can make the HF get worse. The common causes are: inadequate supply of blood to the heart or a part of the heart muscles, usually from obstructed blood flow; high blood pressure; aortic or mitral valve disease; weak heart muscles; and diabetes. Less common and rare causes are known. Modern HF management includes timely detection and treatment of these to try to prevent worse HF.
Other disorders or diseases in addition to the primary HF disease have effects. These include: anemia; pulmonary disease such as chronic obstructive pulmonary disease; sleep-disordered breathing; kidney disease; liver disease; and depression.
Strategies for heart failure
At age 40 the lifetime risk of developing heart failure (HF) is 1 in 5. As life expectancy has gradually increased, so has both the number of patients needing treatment and the total costs. People also become more of a burden on both younger relatives and friends, and on hospitals. So its desirable both to prevent HF if possible and to have services that provide whatever is needed. The already substantial financial burden is likely to significantly increase in the future.
The costs grow with high rates of hospital readmissions; so the strategies aim to keep patients as healthy as possible.
Multidisciplinary management programmes have been devised that unify their care within hospital, outpatient clinic, and community setting. Methods include face-to-face and telephone consultation, and telemedicine. It needs prompt assessment, supervised medical treatment including adjusting drug doses, access to care, patient education, and psychosocial support. So we have nurses and doctors who specialise in HF; with input from pharmacists and other health staff. Patients at risk, such as those with chronic HF, get immunisation against flu. Therapy includes drugs to limit fluid retention, but unfortunately these don't reduce mortality. Drugs include: statins, ACE inhibitors, betablockers, anticoagulation, and drugs that increase the strength of heart muscle contraction. Other treatments include implantable cardiac defibrillators, stents, bypass grafts, and transplants.
Heart-lung machine During an operation this equipment produces for the rest of the patient’s body the effects of the heart and lungs. It has a pump and tubes for the blood to flow to and from the patient’s body that connect to the aorta and a vein near the heart. It also performs the equivalent of the lungs.
Heart rate or heartrate means the number of beats per minute. Pulse means the same, from to take the pulse meaning to measure it.
The normal adult rate is about 60 to 80 beats per minute. It is higher in babies and children, and rises during exercise.
The heart rate maximum for a very fit healthy adult when exercising is about 220 minus age; but most non-sports people are advised to restrict their maximum exercise to somewhat lower than that – say 65% of that or perhaps to 180 minus age. Some sports people have trained so well that their exercise heart rate does not increase as much as those that are not so fit.
The heart rate may also increase with fear, stress, blood loss, injury, and/or some illnesses. It may decrease with hypothermia, low thyroxine, fainting, emotional shock, and/or some heart conditions.
High heart rate may be an indication of heart failure - it is a minor criterion. See heart failure diagnosis under Heart failure.
Heart UK or H.E.A.R.T U.K is a charity formed on 27 June 2002 by a merger of the Family Heart Association and the British Hyperlipidaemia Association. It regards itself as The Cholesterol Society. See also Cholesterol_UK.
About 1 in 500 people have inherited high cholesterol, ie their genetic condition causes their liver to produce too much cholesterol; and Heart UK aims to help them. Like the BHF and the BCPA, they publish various information sheets. The BCPA and Heart UK co-operate. Tel 01628 628 638, www.heartuk.org.uk
Heparin. See under Anticoagulant.
Hepatitis see hepatitis under AST.
High blood pressure. See Hypertension.
High-density lipoprotein, HDL. See HDL under Cholesterol.
Histamine is an amine formed from histidine that is released by body tissues in allergic reactions that cause irritation. It dilates blood vessels, contracts smooth muscle, and stimulates gastric secretions. Formula C5H9N3. See antihistamine.
Antihistamines are treatments for all kinds of allergic reactions. They are subdivided according to their chemical structure – so each subgroup has different actions and/or characteristics. Topical creams applied to the skin mainly act on the muscles surrounding the small blood vessels that supply the skin and mucous membranes – eg brand name Anthisan. Other antihistamines act on airways in the lungs thus reducing congestion and breathlessness; or on the brain giving a sedative effect and suppressing the coughing and vomiting mechanisms.
Antihistamines block the action of histamine on H1 receptors, which are in various body tissues eg the small blood vessels in the skin, nose and eyes. The antihistamines help to prevent the dilation of the vessels – thus reducing swelling, watering, and redness. Antihistamines also reduce the secretions from tear glands and nasal passages.
Antihistamines may cause drowsiness – affecting coordination, and hence cause clumsiness; and may have side effects such as dry mouth, blurred vision, and difficulty passing urine. So it may be advisable to avoid driving. They also increase or cause similar effects to alcohol, sleeping drugs, opioids, and anti-anxiety drugs.
Histidine is a sweet-tasting crystalline amino acid that occurs in most proteins – a precursor of histamine. Formula C3H3N2CH2CH(NH2)COOH.
Hives is a non-technical name for Urticaria.
Holter monitor means Event monitor.
Homocysteine is an amino acid, which is explained under organic chemistry.
Patients with too high level of it in their blood are at increased risk of having a stroke. Eating more fruit and vegetables and/or taking folic acid supplements reduces the level and cuts the risk of a stroke. A patient's level of homocysteine can be determined from a blood test.
Lower levels of homocysteine are statistically linked to reduced risk of CHD and of Alzheimer's disease.
Hormone. A hormone is a chemical produced in an endocrine gland and transported in the blood to a particular tissue where it exerts a particular effect.
The main drug groups are Corticosteroids; and drugs for diabetes, pituitary, sex hormone, and thyroid disorders.
Hospital alcohol gel see Hospital alcohol gel under Alcohol.
HR See Hazard ratio.
HRI is an abbreviation for the Heart Related Information documents previously available from the BCPA, but now all out of print.
Human Nutrition Unit HNU is next to the Institute of Food Research on Norwich Research Park. It does nutrition studies on human volunteers. Tel 01603 255000.
Humerus. The bone in the upper arm. A knock on the elbow end produces a funny sensation – hence funny bone.
The lower arm bones are the radius on the thumb side, and the ulna on the little finger side. See Elbow.
Hydrogenation. See under monounsaturated fats.
Hydroxyl group see hydroxyl group under organic chemistry.
Hyper- means too much, in excess; or above, over. Contrast with hypo-.
Hypercholesterolaemia means too much cholesterol. Hyperlipidaemia means too high lipids, usually too high LDL. See Cholesterol and lipid.
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. The terms for total cholesterol are as follows.
- ideal cholesterol level: less than 4.8mmol/l - see under cholesterol HDL and LDL
- too high cholesterol level: between 5 and 6.4mmol/
- very high cholesterol level: between 6.5 and 7.8mmol/l
- extremely high cholesterol level: above 7.8mmol/l
In diagnosis and decisions on treatment doctors also have to consider: the HDL to LDL ratio - explained under cholesterol HDL and LDL, and the presence of other risk factors for cardiovascular disease, such as smoking, diabetes, and high blood pressure.
These other factors when present increase the sensitivity of the body to harm through cholesterol. It is possible for someone to have a high level of total cholesterol and still have a relatively low cardiovascular risk because of an absence of other risk factors or because their family history is free from coronary disease. Patients who have had cardiovascular disease such as angina, a previous heart attack, coronary angioplasty or coronary artery bypass surgery should keep their total cholesterol and LDL levels as low as possible, as explained under cholesterol and under cholesterol HDL and LDL.
As stated under Eggs Eating eggs is OK, the only people advised not to eat too many eggs are those with familial hypercholesterolaemia, which is a metabolic disease from a congenital defect in the LDL receptor gene resulting in dysfunctional or absent receptors. In the UK it affects about 1 in 500 people. Familial here means with family history, ie inherited.
Hypertension HT is commonly called high blood pressure, nowadays defined as persistently above 140/90mm Hg - ie either the systolic is above 140 or the diastolic above 90 or both.
About 38% of UK adults have hypertension at any one time. Correct treatment of hypertension reduces the risk of a heart attack by about 20% and reduces the risk of stroke by about 40%. Most people with hypertension need tablets to lower their blood pressure. Advice and treatment includes exercise, lifestyle changes, and/or diet changes, as well as drugs.
About 6 million UK patients take drugs to help control their BP. Half these are over 60. There are 350 preventable strokes and heart attacks per day caused by high BP. In developed countries the risk of suffering high BP sometime in one's lifetime is about 90%.
See separate factsheet on Hypertension – High Blood Pressure.
Hypertrophic, hypertrophy, is enlargement of an organ or part of an organ resulting from an increase in the size of the cells. Eg see cardiomyopathy.
Hyperventilation is increased breathing rate, duration, depth, and/or volume. This may cause cramp or dizziness.
Hypo- means too little, less than enough; or under, beneath, below. Contrast with hyper-.
Hypothermia is too low body temperature, eg below about 35 C (95 F). This can develop slowly over several days in a cold building in winter. Outdoors this is usually from cold, wet and/or wind. Otherwise, eg in older people, it may be related to metabolic rate and/or thyroxine deficiency, as explained under Metabolism. Older people are less able to compensate for temperature changes, and being less sensitive to cold may not initially respond to a slight drop in temperature. The elderly are at risk if they have poor heating or do not switch it on, are thin or frail, have arthritis and/or are not able to get about, are tired, and/or are ill.
Hypothermia has several stages. See also consciousness.
● Feeling slightly cold, perhaps shivering, possibly with cold pale dry skin – people put more clothing on and recover quickly, and this is normal
● Deteriorating performance, which others usually notice before the subject himself or herself does; perhaps with not responding normally to questions, apathy, irrational behaviour, or arguing; and the elderly may delay preparing and eating food
● Serious, where the shivering stops, slowness, lethargy, little or no participation in activities, not even responding to commands, slow or shallow breathing, slow and weak pulse, just lying down
● Lapsing into unconsciousness, perhaps eventually leading to a heart attack or cardiac arrest.
The body systems react by trying to preserve life – keeping the heart, brain and essential functions working, and reducing the blood flow to the extremities by narrowing the arteries.
Hypothermia Treatment: in serious cases always call a doctor or ambulance or take the patient to hospital, as the hypothermia may hinder recognition of a heart attack or stroke.
If a patient at home got cold slowly and is in the early not serious stages, warm them slowly. Rapid warming such as in a hot bath would be wrong, as initially it would cause the skin blood vessels to dilate; and blood would flow to the extremities, rather than to the central organs that are vital for survival and life. It would also initially cause more cold blood than previously flowing to return from the extremities back to the heart, and thus tend to cool the brain and other vital organs.
For healthy people who have got very cold outdoors: remove the patient from the cold, wet and wind eg to a building or tent; put on dry clothing; let them lie down in a bed with extra duvet or blankets or in a sleeping bag and survival bag; and/or they can have a hot bath.
Hypothesis. See Statistically significant.
Hypothyroidism and Hyperthyroidism. See under thyroxine.
Copyright
This information was created and edited by Richard Maddison for the BCPA.
Copyright © 1997-2013 The British Cardiac Patients Association, and/or Richard Maddison.
BCPA Head Office: 15 Abbey Road, Bingham, Nottingham NG13 8EE
Reg Charity 289190. Email: Admin@BCPA.co.uk
First published in this form 2002, and updated 2005, 2007, 2008, 2011, 2012, 2013.
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 www.bupa.co.uk/health-information.
We hope we have thanked everyone.
Richard Maddison