A myocardial infarction (MI) or heart attack means death of ('infarction') part of the heart muscle ('myocardium'). This usually occurs when one of the blood vessels supplying the heart (the coronary arteries) suddenly becomes blocked. The blockage prevents blood from travelling further down the vessel, thereby depriving the part of heart supplied by that vessel of its oxygen supply. Thus deprived of its oxygen, the affected part of the heart becomes damaged and, if the blood supply is not quickly restored, undergoes the process known as infarction ('it dies').
Heart attacks can vary in severity from, depending on the position of the blockage and thus the amount of heart damaged, a massive MI (which is usually associated with sudden loss of consciousness and almost always death if not immediately treated) to an episode of chest pain and breathlessness which, although very distressing for the individual, does not usually cause loss of consciousness and which can often be treated successfully with many people making a full recovery.
Heart attacks become more common with increasing age and men are more than twice as likely as women to be affected. For reasons that we will shortly discuss MI's often occur in people who are known to have heart problems - so called ischaemic heart disease or angina, but they can also occur "out of the blue" in people who have not had any previous heart symptoms.
The sudden blockage of a coronary artery causing a MI is usually due to a "thrombosis" or blood clot developing inside the vessel. Normally blood does not clot inside blood vessels, because of complex processes which keep it in a liquid state. However, if the lining of the blood vessel becomes damaged and cracked, the circulating blood becomes exposed to substances inside the vessel wall which triggers a set of chemical reactions resulting in the formation of solid clot or "thrombus".
This solid clot develops quickly and can easily cause blockage of the blood vessel with consequent interruption to the blood supply. The lining of healthy coronary arteries does not normally crack but in the presence of atheroma cracks can more easily develop. Atheroma is a form of fatty material (derived from cholesterol), which is deposited in lumps or 'plaques' on the inner aspect of blood vessels often causing a protrusion of the lining of the blood vessel into its cavity. The narrowing resulting from these fatty lumps can cause a reduction in blood flow producing angina.
Heart attacks usually cause symptoms of severe chest pain, which is felt across the chest and often travels up into the neck/jaw and down the left or both arms. This is accompanied by breathlessness, sweating and nausea. When this occurs in someone who has angina, the symptoms are essentially similar but typically more severe than the usual anginal symptoms and do not settle with anti angina medication. Anyone who develops sudden severe persisting chest pain should seek medical attention immediately by dialling 999.
Treatment for heart attacks has recently improved greatly. In hospital special 'clot busting' drugs are given via an injection to dissolve the blood clot responsible as quickly as possible to allow the normal blood flow to be restored, hopefully before the area of heart thus far deprived of its oxygen supply has been irreversibly damaged.
Once out of hospital it is important to take the advice of your hospital cardiac rehabilitation nurse or GP and aim to gradually increase physical activity over the first six weeks, hopefully returning to work by three months providing this is not particularly strenuous. It is normally safe to drive a car (although not a PSV/HGV vehicle) after four weeks, although your insurance company needs to be notified. Flying can usually occur from six weeks.
In the past people were advised to rest and recuperate for many months after a heart attack and then to take it generally easy in the future. Unfortunately this was not needed and resulted in many people unnecessarily restricting their activities for fear of causing further problems. Sex, in particular was a cause for concern and it is important to realise that although best avoided for a few weeks after a MI, it should be safe to return to normal sexual activity from then on if you are able to walk without developing symptoms of angina.
Following a heart attack your doctor will want to work with you to reduce your chances of having further problems. Close attention will be paid to your blood pressure, weight, cholesterol level, diet and degree of exercise. If you smoke, there has never been a more important reason to stop. Several types of medication are often prescribed after a heart attack to reduce the risk of further problems and to control any associated angina. In particular, it is usually recommended (unless there is a medical contraindication) to take a low dose Aspirin tablet each day as this 'thins the blood', thereby reducing its stickiness and lessening the chance of a thrombus forming on an area of atheroma.
Many people are alive and enjoying full and active lives 20-30 or even 40 years after having a heart attack. Your doctor will help you to help yourself minimise the chance of having any further problems and will normally keep a regular check up on you to monitor your blood pressure, cholesterol etc.
Disclaimer: This page is for informational purposes only and should not be considered as medical advice or substituted for professional advice. Always consult your doctor with your questions and concerns.
Material Copyright © 2000-2008 Wellway Medical Group