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HEART ATTACK - MYOCARDIAL INFARCTION

What is a Heart Attack ?

Infarction means damage to an organ or part of an organ (in this case, the heart) due to interruption of its fuel supply (the oxygen carried by the blood). This is often called a heart attack or coronary thrombosis. It means that the coronary artery, which supplies fuel to the heart is blocked, usually by a blood clot. The usual symptom is chest pain, which sometimes comes without warning and may be mistaken for indigestion. It is usually in the middle of the chest or on both sides. It may spread into the neck, shoulders, arms or back and is occasionally just felt on one side. It is similar to the pain of angina (see below) but lasts longer. It is often associated with sweating, feeling sick or vomiting. Occasionally, a myocardial infarction occurs without pain.

How does a Heart Attack occur ?

The coronary artery usually blocks at a point which has previously narrowed. The narrowing may have developed without any symptoms. Some patients, however, will have previously experienced angina. This is a similar but more short-lived pain, brought on by physical stress or emotion and relieved by rest. Angina is due to reduction of blood flow due to a narrowing of a coronary artery: infarction is caused by a complete blockage of blood flow. The pain lasts longer and there is damage to the muscular wall of the heart.

Why does a Heart Attack occur ?

The coronary arteries narrow due to thickening of the walls. Fatty substances are deposited in the internal lining, damaging the wall and forming a ‘plaque’. This may rupture causing a complete blockage. However, in most cases, a blood clot, which forms at the point of maximum narrowing, leads to the blockage. This whole process is commonest in males beyond the age of 40 but increasingly is affecting women also, especially after the menopause.

Treatment Involved for a Heart Attack

DIAGNOSIS Someone with suspected heart attack is admitted to hospital as quickly as possible. Many areas now have ambulances staffed by specially trained paramedics and equipped as a mobile coronary care unit (CCU). Ideally, you will be looked after in the hospital CCU for the first day or two. The diagnosis is often clear from a description of the chest pain. An electrocardiogram (ECG) is the usual way of making the diagnosis. Typical changes in the electrical waves tell the doctor what has happened. The heart attack can be confirmed using blood tests called cardiac markers. These are chemicals (most commonly creatine kinase [CK] and troponin) which are normally found inside heart muscles. They are released into the blood when heart?muscle cells are damaged. TREATMENT If you are not taking aspirin already, a single 300mg dose should be taken as soon as the diagnosis is clear. This prevents further build up of blood clot. A cannula or tube is usually put into an arm vein to give painkillers and other drugs. Oxygen may be given through a face mask or nasal tubes and you will be connected to a continuous ECG monitor. Sometimes the most important treatment involves giving blood?clot?dissolving (thrombolytic) medication into a vein. This only works when given in the first few hours after the heart attack, but may considerably reduce damage to the heart This treatment may cause bleeding and is normally used only when the diagnosis is definite. Electrical problems are common. The heart has an electrical system to get the timing right and immediately after a heart attack this may become disorganised. Abnormal heart rhythms can develop suddenly. This is why patients are kept in a CCU for a day or two. Occasionally a temporary pacemaker may be used for slow heart rhythms and drugs used to treat or prevent a rhythm change. This is rarely serious because the heart has a large reserve of function. If necessary, drugs are given to support the pumping. For the first few days, rest is an important part of treatment. Once you leave CCU, activity is gradually encouraged: just getting out of bed at first, then walking around the ward. By the time you go home, you should be able to walk around the house and cope with stairs once or twice a day.

During Treatment for a Heart Attack

Heart failure may occur after a heart attack because the damaged heart muscle reduces the efficiency of its pumping action. If this happens, it causes fluid to be retained. This leads to breathlessness or swelling of the feet and ankles. This requires treatment, usually with diuretics (water pills). Angina may occur, even if not there previously.

After Treatment for a Heart Attack

Most patients need other tests once the heart attack has settled. An exercise test is usually done to assess future risks. Many will also need a special x?ray to view the arteries (coronary arteriography). This may be the only way of finding out whether a procedure may be needed to reduce the risk of a future heart attack. Such procedures consist of stretching an artery (coronary angioplasty) or an operation for creating new channels for the coronary arteries (coronary artery bypass grafting). A convalescent period of around 8 weeks is usual, at the end of which your activity should be back to normal. Progress is governed by common sense. Most hospitals now run rehabilitation programmes to allow a gradual increase in activity under observation: this encourages confidence. Then a short holiday is sensible, followed by a gradual return to work. PREVENTING FURTHER ATTACKS It is important to know about the "risk factors" which may have led to your coronary disease and the heart attack. Changes in lifestyle may be necessary. It is important to stop smoking completely, have regular healthy exercise, modify diet, and reduce weight. If necessary, raised blood pressure, raised cholesterol and diabetes are carefully treated. Aspirin should be continued and various other medications known to reduce the risk for future heart problems are considered. The include statins which lower cholesterol, and ACE inhibitors and beta-blockers, both of which act to reduce the work of the heart. There may be reasons why certain people should not take them, however and you need to discuss them with your doctor.

If a Heart Attack is Left Untreated

Some people can have a virtually painless heart attack without realising it. It may only show up on an ECG done much later for another reason. They have obviously done well without treatment! However, a heart attack is potentially life?threatening and it is important that, if you think it may be happening, you place yourself in medical hands, preferably in hospital, as soon as possible. Abnormal heart rhythms and heart failure can both interfere with the pumping action and may seriously affect recovery. They may even be fatal.

Effects on Family of a Heart Attack

You will need the help of your family and friends during your convalescence. This allows your activity to be increased slowly. After 2 to 3 months, you should be back to normal and need no further help. If your cholesterol levels were abnormal, checks of your brothers and sisters may be worthwhile. Although there is no definite test to say who is likely to get a heart attack, it is generally considered wise for such family members to follow preventive guidelines.