goodtoknow says: Heart attacks, sometimes called a coronary thrombosis or myocardial infarction, are very common. Although serious, new treatments and better understanding of the heart mean that your chances of making a complete recovery are extremely good. Heart attacks are usually caused by a blood clot (thrombosis). The main symptoms of heart attacks are severe chest pain that can travel into your arms, making you sweat, feel sick or faint. If you think you're having a heart attack call a doctor or ambulance immediately. Giving up smoking, losing weight and eating a low fat diet will all reduce your risks of a heart attack.
For a full medical explanation of the causes, symptoms and treatments of myocardial infarction from patient.co.uk, read on.
Myocardial infarction (MI) is usually caused by a blood clot in a heart (coronary) artery. Phone for medical help immediately if you develop severe chest pain. A 'clot busting' drug should be given as soon as possible to prevent damage to heart muscle. Also, other treatments help to ease the pain and prevent complications. Reducing risk factors can help to prevent an MI.
Myocardial infarction (MI) means that part of the heart muscle suddenly loses it's blood supply. Without prompt treatment, this can lead to damage to the affected part of the heart. An MI is sometimes called a heart attack or a coronary thrombosis.
The heart is mainly made of special muscle. The heart pumps blood into arteries (blood vessels) which take the blood to every part of the body.
Like any other muscle, the heart muscle needs a good blood supply. The coronary arteries take blood to the heart muscle. The main coronary arteries branch off from the aorta. (The aorta is the large artery which takes oxygen-rich blood from the heart chambers to the body.) The main coronary arteries divide into smaller branches which take blood to all parts of the heart muscle.
If you have an MI, a coronary artery or one of it's smaller branches is suddenly blocked. The part of the heart muscle supplied by this artery loses it's blood (and oxygen) supply. This part of the heart muscle is at risk of dying unless the blockage is quickly undone. (The word 'infarction' means death of some tissue due to a blocked artery which stops blood from getting past.)
If one of the main coronary arteries is blocked, a large part of the heart muscle is affected. If a smaller branch artery is blocked, a smaller amount of heart muscle is affected. In people who survive an MI, the part of the heart muscle that dies ('infarcts') is replaced by scar tissue over the next few weeks.
The common cause of an MI is a blood clot (thrombosis) that forms inside a coronary artery, or one of its branches. This blocks the blood flow to a part of the heart.
Blood clots do not usually form in normal arteries. However, a clot may form if there is some atheroma within the lining of the artery. Atheroma is like fatty patches or 'plaques' that develop within the inside lining of arteries. (This is similar to water pipes that get 'furred up'.) Plaques of atheroma may gradually form over a number of years in one or more places in the coronary arteries. Each plaque has an outer firm shell with a soft inner fatty core.
What happens is that a 'crack' develops in the outer shell of the atheroma plaque. This is called 'plaque rupture'. This exposes the softer inner core of the plaque to blood. This can trigger the clotting mechanism in the blood to form a blood clot. Therefore, a build up of atheroma is the root problem that leads to most cases of MI. (The diagram above shows four patches of atheroma as an example. However, atheroma may develop in any section of the coronary arteries.)
'Clot busting' drugs (see below) can break up the clot and undo the blockage. If given quickly enough this prevents damage to the heart muscle, or limits the extent of the damage.
Various other uncommon conditions can block a coronary artery and cause an MI. For example: inflammation of the coronary arteries (rare); a stab wound to the heart; a blood clot forming elsewhere in the body (for example, in a heart chamber) and travelling to a coronary artery where it gets stuck; cocaine abuse which can cause a coronary artery to go into spasm; complications from heart surgery; and some other rare heart problems. There are not dealt with further.
The rest of this leaflet only deals with the common cause - thrombosis over an atheroma plaque.
About 180,000 people in the UK are admitted to hospital each year with an MI. Most MIs occur in people over 50, and become more common with increasing age. Sometimes younger people are affected. An MI is three times more common in men than women. An MI may occur in people known to have heart disease such as angina. It can also happen 'out of the blue' in people with no previous symptoms of heart disease. (Atheroma often develops without any symptoms at first.)
Severe chest pain is the usual main symptom. The pain may also travel up into your jaw, and down your left arm, or down both arms. You may also sweat, feel sick, and feel faint. The pain may be similar to angina, but it is usually more severe and lasts longer. (Angina usually goes off after a few minutes. MI pain usually lasts more than 15 minutes - sometimes several hours.)
A small MI occasionally happens without causing pain (a 'silent MI'). It may be truly pain-free, or sometimes the pain is mild and you may think it is just heartburn or 'wind'.
Collapse and sudden death may occur with a large or severe MI.
Call an ambulance or doctor immediately. The earlier the treatment, the better the chance of a good outcome. The following describes a typical course of events that then occurs.
Many people recover well from an MI and have no complications. Before discharge from hospital it is common for a doctor or nurse to advise you how to reduce any risk factors (see below). This advice aims to reduce your risk of a future MI as much as possible. An exercise test may also be done. Briefly, this helps to tell how badly the coronary arteries are narrowed with atheroma, and whether more complex tests of the heart need to be done.
Note: the common 'clot buster' drug used in the UK is called streptokinase. If you are given this drug you should not be given it again if you have another MI in the future. This is because antibodies develop to it and it will not work well a second time. An alternative 'clot buster' drug should be given if you have another MI in the future.
Emergency angioplasty is used in some cases as an alternative to a 'clot busting' drug in some hospitals. In this procedure a tiny wire with a balloon at the end is put into a large artery in the groin or arm. It is then passed up to the heart and into the blocked section of a coronary artery using special x-ray guidance. The balloon is then blown up inside the blocked part of the artery to open it wide again.
This often depends on the amount of heart muscle that is damaged. In many cases only a small part of the heart muscle is damaged (infarcts or dies) which heals as a small patch of scar tissue. The heart can usually function normally with a small patch of scar tissue. A larger MI is more likely to be life-threatening or cause complications.
Even before 'clot busting' drugs became available, many people made a full recovery as many MIs are small. With the help of modern treatment, particularly if you are given a 'clot busting' drug quickly, a higher percentage of people now make a full recovery.
Some possible complications that may occur after an MI include the following.
The most crucial time is during the first day or so. If no complications arise, and you are well after a couple weeks, then you have a good chance of making a full recovery. A main objective then is to get back into normal life, and to minimise the risk of a further MI.
After recovering from an MI, it is natural to wonder if there are any 'dos and don'ts'. In the past, well-meaning but bad advice to "rest and take it easy from now on" caused some people to become over-anxious about their hearts. Some people gave up their jobs, hobbies, and any activity that caused exertion for fear of 'straining the heart'.
However, quite the opposite is true for most people who recover from an MI. Regular exercise and getting back to normal work and life is usually advised. Much can be done to reduce the risk of a further MI.
Everybody has a risk of developing atheroma which can lead to an MI. However, certain 'risk factors' increase the risk and include:
Briefly, if you can reduce any risk factors, it reduces your risk of having an MI (or of having a further MI if you have already had one). Some risk factors are fixed and you cannot change them. However, if you have a fixed risk factor, you may want to make extra effort to reduce preventable risk factors such as smoking or lack of exercise.
British Heart Foundation 14 Fitzhardinge Street, London, W1H 4DH Heart Information Line: 0845 070 8070 (Mon-Fri 9am-5pm) Web: www.bhf.org.uk
© EMIS and PIP 2006 Updated: February 2006 PRODIGY Validated